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Neurobiology of axonal transport defects in motor neuron diseases: Opportunities for translational research?

Kurt J. De Vos, Majid Hafezparast

Neurobiology of Disease · 2017 · Review · CC BY

doi:10.1016/j.nbd.2017.02.004

Abstract

Intracellular trafficking of cargoes is an essential process to maintain the structure and function of all mammalian cell types, but especially of neurons because of their extreme axon/dendrite polarisation. Axonal transport mediates the movement of cargoes such as proteins, mRNA, lipids, membrane-bound vesicles and organelles that are mostly synthesised in the cell body and in doing so is responsible for their correct spatiotemporal distribution in the axon, for example at specialised sites such as nodes of Ranvier and synaptic terminals. In addition, axonal transport maintains the essential long-distance communication between the cell body and synaptic terminals that allows neurons to react to their surroundings via trafficking of for example signalling endosomes. Axonal transport defects are a common observation in a variety of neurodegenerative diseases, and mutations in components of the axonal transport machinery have unequivocally shown that impaired axonal transport can cause neurodegeneration (reviewed in El-Kadi et al., 2007, De Vos et al., 2008; Millecamps and Julien, 2013). Here we review our current understanding of axonal transport defects and the role they play in motor neuron diseases (MNDs) with a specific focus on the most common form of MND, amyotrophic lateral sclerosis (ALS).

Full text

From PubMed Central, U.S. National Library of Medicine, as current on Oct 20, 2026. Paragraph numbers are ours, so an answer can point at one.

Microtubule-based axonal transport

Traditionally two main classes of axonal transport are distinguished based on the overall speed of movement, namely fast axonal transport (~ 50–400 mm/day or 0.6–5 μm/s) and slow axonal transport (0.2–10 mm/day or 0.0002–0.1 μm/s). Slow axonal transport is further subdivided into slow component a (SCa) and b (SCb) based on the proteins transported and the speed, 0.2–3 and 2–10 mm/day, respectively. We now know that both fast and slow axonal transport is mediated by the same molecular motors that move cargoes along microtubules, with the differences in overall speed caused by prolonged pauses between movement phases in slow axonal transport (reviewed in ).

Microtubules are polymers made up of tubulin which itself is a heterodimer of α-tubulin and β-tubulin. Microtubules are rigid hollow rods of approximately 25 nm in diameter built from 13 linear protofilaments composed of alternating tubulin heterodimers and arranged around a hollow core. Due to the head to tail arrangement of the tubulin heterodimers microtubules are polarised with a fast growing plus end and a slow growing minus end. The polarity of microtubules dictates the direction of movement of the molecular motors along them.

There are two major families of microtubule based molecular motors, namely the kinesin family which move mostly toward the plus end of microtubules and the cytoplasmic dyneins that move toward the minus end (reviewed in ). Because axonal microtubules are uniformly orientated with their plus end pointing away from the cell body kinesins mediate anterograde transport away from the cell body toward the axon terminal and cytoplasmic dynein drives retrograde transport from the distal axon toward the cell body.

The human kinesin superfamily contains 45 members, subdivided into 15 subfamilies. The main kinesin family members involved in fast axonal transport are kinesin-1 (previously referred to as conventional kinesin or KIF5), and the kinesin-3 family members KIF1A, KIF1Bα and KIF1Bβ. Anterograde slow axonal transport appears to be mainly mediated by kinesin-1. Kinesin-1 is a heterotetramer consisting of two kinesin heavy chains (KHCs) and two kinesin light chains (KLCs). KHC contains the catalytic motor domain, a neck linker region, an α-helical stalk interrupted by two hinge regions, and the tail. The motor domain binds microtubules and hydrolyses ATP to generate force. Together with the neck region, the motor domain conveys processivity and direction of movement. The stalk is required for dimerisation and the tail, together with KLC is involved in regulation of motor activity as well as cargo binding (reviewed in ). The latter also involves various adapter proteins such as c-Jun N-terminal kinase (JNK)-interacting protein (JIP) 1, 3 and 4, mitochondrial Rho GTPase (Miro) 1 and 2, trafficking kinesin (TRAK) 1 and 2, and huntingtin that link kinesin-1 to specific cargo, directly or via KLCs (reviewed in ). In contrast to kinesin-1, KIF1A and KIF1Bα/β are monomeric kinesin motors consisting of an N-terminal motor domain, a conserved stalk domain and a C-terminal pleckstrin homology (PH) that aids in the interaction with cargoes in conjunction with adapter proteins such as DENN/MADD (Differentially Expressed In Normal And Neoplastic Cells/MAP Kinase Activating Death Domain). Kinesin-1 transports a number of different fast axonal transport cargoes including mitochondria and a variety of vesicular and non-vesicular cargoes such as lysosomes, signalling endosomes (e.g. brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase (Trk) B (TrkB) vesicles), amyloid precursor protein (APP) vesicles, AMPA vesicles, and mRNA/protein complexes. Kinesin-1 also mediates the slow axonal transport of cytoskeletal cargoes such as microtubules and neurofilaments (reviewed in ). KIF1A and KIF1Bβ motors transport synaptic vesicle precursors, signalling endosomes such as TrkA vesicles, and the autophagy protein ATG9. KIF1Bα has also been proposed to drive anterograde transport of mitochondria.

In contrast to the multiple kinesins that drive anterograde transport, retrograde transport is almost exclusively mediated by a single cytoplasmic dynein. Cytoplasmic dyneins are members of the ATPases associated with diverse cellular activities (AAA +) family of ATPase proteins. They are sub-divided into cytoplasmic dynein 1 and 2, with cytoplasmic dynein 1 being the main retrograde molecular motor in neurons. Cytoplasmic dynein 1 (hereafter referred to as dynein) is composed of two homodimerised dynein heavy chains (DHCs) and multiple dynein intermediate (DIC), dynein light intermediate (DLIC), and light chains (LC) (reviewed in ). The assembly of these polypeptides forms a ~ 1.5 MDa protein complex whose functions, cargo binding and localisation are regulated by adapter complexes including dynactin, Bicaudal D2 (BICD2), lissencephaly 1 (LIS1), nuclear distribution protein (NUDE or NDE) and NUDE-like (NUDEL or NDEL). The ~ 1 MDa dynactin complex contains p150Glued which interacts with a short actin-like Arp1 filament and various additional dynactin subunits including p50/dynamitin, p62, CapZ, p27, p25, and p24. p150Glued associates with dynein via the DICs and also directly binds to microtubules; through its cargo-binding domain p150Glued binds a number of vesicular cargo adapters, including sorting nexin 6 (SNX6), huntingtin-associated protein 1 (HAP1) and JIP1 (reviewed in, ).

Axonal transport defects in ALS

ALS, the most common form of MND, is an adult onset and progressive neurodegenerative disorder caused by selective injury and death of upper motor neurons in the motor cortex and lower motor neurons in the brain stem and spinal cord. Degeneration of motor neurons leads to progressive muscle wasting followed by paralysis and usually culminates in death through respiratory failure. ALS has an incidence of 2 per 100,000 and a mean age of onset of 55–65 years. The average survival is approximately 3 years from symptom onset (reviewed in ). An estimated 10% of ALS is inherited, usually in an autosomal dominant fashion (familial ALS), but most ALS cases have no clear genetic basis and occur seemingly random in the population (sporadic ALS). Several genes have been associated with familial ALS, including superoxide dismutase 1 (SOD1) (~ 12% of familial cases), TAR DNA binding protein (TARDBP; TDP-43) (~ 4%), Fused in sarcoma (FUS) (~ 4%), and C9orf72 (~ 40%) (reviewed in ). The causes of motor neuron degeneration appear multifactorial. From research mostly on familial ALS cases and animal models a number of possible pathogenic mechanisms underlying motor neuron degeneration have emerged including oxidative stress, mitochondrial dysfunction, misfolded protein toxicity/autophagy defects, RNA toxicity, excitotoxicity, and defective axonal transport (reviewed in,, ).

Axonal pathology

Early evidence for axonal transport defects in ALS came from electron microscopy and neuropathological studies of post-mortem ALS cases that revealed abnormal accumulations of phosphorylated neurofilaments (a pathological hallmark of ALS), mitochondria and lysosomes in the proximal axon of large motor neurons and axonal spheroids containing a variety of vesicles, lysosomes, and mitochondria as well as neurofilaments and microtubules (Fig. 1). Consistent with damage to the axonal transport machinery as an underlying cause, hyperphosphorylated neurofilament heavy polypeptide (NF-H) positive spheroids stained strongly for KHC but, interestingly, not dynein.

Direct evidence for axonal transport defects in ALS was obtained following the development of mutant SOD1 transgenic mouse strains as mammalian animal models of ALS. Sciatic nerve ligation in SOD1G93A transgenic mice revealed a significant reduction of immune-reactive kinesin-1 on the proximal side of the ligation in both younger asymptomatic and older presymptomatic transgenic mice whereas a marked reduction in dynein immunoreactivity was apparent only in the presymptomatic mice. Both defects correlated with significant spinal motor neuron loss, reduced myelinated fibre densities in the sciatic nerve, and muscle pathology. Metabolic labelling experiments revealed a significant reduction in the slow anterograde transport of cytoskeletal components months before the onset of neurodegeneration in SOD1G37R transgenic mice while both slow and fast axonal transport were found to be impaired in SOD1G93A transgenic mice.

Endosome trafficking and retrograde signalling

Detailed analysis of axonal transport of specific cargoes in primary neurons and in vivo further confirmed these early studies. Time-lapse recording of a fluorescently labelled fragment of the tetanus toxin TeNT HC which is transported in the same compartment as neurotrophins, revealed defective dynein-mediated retrograde transport in motor neurons isolated from SOD1G93A transgenic embryos and in vivo in the intact sciatic nerve of presymptomatic SOD1G93A transgenic mice. Further evidence for the involvement of perturbed dynein-mediated retrograde axonal transport was provided by examining the transport of a neurotracer to the soma of spinal motor neurons following its injection to the gastrocnemius muscle in SOD1G93A transgenic mice. This investigation demonstrated a significant reduction in retrograde axonal transport, which temporally correlated with disease progression. Similarly, direct time-lapse recordings of fluorescently labelled TrkB vesicles revealed defective retrograde transport in SOD1G93A expressing neurons. Interestingly, mutations in alsin (ALS2), which cause juvenile-onset ALS, disturb its Rab5-GEF activity and consequently disrupt Rab5-dependent endosome trafficking and AMPA receptor trafficking. Since retrograde neurotrophin trafficking requires Rab5 activity alsin mutations may thus cause neurodegeneration by inhibition of retrograde axonal transport. Along the same lines it has been shown that ALS mutant charged multivesicular body protein 2B (CHMP2B) impairs recruitment of Rab7 to endosomes. Because Rab7 is also required for retrograde neurotrophin signalling, disrupted retrograde trafficking may explain the neuronal inclusion formation and axonal degeneration in mutant CHMP2B transgenic mice. In contrast to the retrograde-specific inhibition of axonal transport of TrkB signalling endosomes, time-lapse recording of EGFP-APP labelled vesicles revealed reduced transport in both anterograde and retrograde directions in mutant SOD1G93A, A4V, G85R or G37R transfected cortical neurons. Nevertheless, this data indicates a possible role for disrupted retrograde signalling in ALS.

Mitochondrial trafficking

Live microscopy revealed reduced anterograde but not retrograde axonal transport of fluorescently labelled mitochondria in cultured cortical neurons expressing ALS mutant SOD1G93A, A4V, G85R or G37R and in embryonic motor neurons expressing SOD1G93A. This defect was later confirmed in vivo by time-lapse measurements in single axons in the intact sciatic nerve of presymptomatic SOD1G93A transgenic mice and rats. In cultured neurons, the transport deficit resulted in depletion of mitochondria from axons and a concomitant increase in inter-mitochondrial distance. In vivo in motor neurons of early symptomatic SOD1G37R and SOD1G85R transgenic mice the number of axonal mitochondria was reduced and their distribution was no longer homogeneous throughout the axon and in SOD1G93A transgenic mice mitochondria were found in abnormal clusters along the axon. Likewise, reduced axonal transport correlated with decreased mitochondrial density in the motor axons of SOD1G93A transgenic rats.

One group reported axonal transport defects in wild type SOD1 transgenic mice that show no neurodegeneration, and no axonal transport defects in SOD1G85R transgenic mice. However, compared to SOD1G93A transgenic mice the onset of the transport defect is later in wild type SOD1 transgenic mice, 2 months after birth in wild type SOD1 transgenic mice compared to postnatal day 20 in SOD1G93A transgenic mice, and only reaches levels comparable to SOD1G93A at 4 months of age. It has been reported that wild type SOD1 transgenic mice exhibit signs of premature aging. Thus, it is possible that the late transport defect in wild type SOD1 transgenic mice is linked to the reductions in transport that have been observed in aging mice. The lack of axonal transport defects in SOD1G85R transgenic mice is in contrast with the reduction in the number of axonal mitochondria and the skewed distribution of mitochondria observed by others, but may be due to the fact that unlike other mutant SOD1 transgenic mice the SOD1G85R transgenic mice only express low levels of the unstable SOD1G85R protein and the mice tend to remain healthy for most of their lifespan, only succumbing to the disease approximately one week before death.

Defects in mitochondrial transport are not limited to SOD1-related ALS. Overexpression of the ALS mutant vesicle-associated membrane protein-associated protein B (VAPB) VAPBP56S caused a selective block in anterograde transport of mitochondria. Similarly, overexpression of wild-type TDP-43 and to a greater extent ALS mutant TDP-43Q331K or M337V reduced mitochondrial transport and mitochondrial density in primary motor neurons. Disruption of axonal mitochondrial transport was also observed in vivo in ALS mutant TDP-43A315T transgenic mice and wild-type TDP-43 and mutant TDP-43M337V overexpressing mice exhibited mitochondrial aggregation consistent with transport defects. It has to be noted that in contrast to these studies, Alami et al. did not find disruption of axonal transport of mitochondria in cortical neurons expressing wild type or mutant TDP-43M337V or A315T at 5–7 days in culture. Moreover, expression of wild type or TDP-43M337V did not affect mitochondrial transport in Drosophila motor axons, although in the same study TDP-43M337V did reduce the KIF1A-dependent motility of dense-core vesicles visualised using NPY-GFP. Possibly, different model systems, neuronal types, and experimental conditions may explain these opposing results.

Expression of either wild type human FUS or the ALS-associated FUS-P525L mutant in Drosophila motor neurons reduced both motility and processivity of mitochondrial axonal transport but this was not observed by others. Interestingly Baldwin et al. did find that expression the fly homolog of FUS, cabeza (caz) and cazP398L, a pathogenic equivalent of human FUS-P525L, inhibited mitochondrial transport. The same authors explored the effects of transgenic expression of C9orf72 GGGGCC (G4C2) repeat expansion constructs on axonal transport and found that a non-pathogenic repeat length (G4C2-3) had no effect on mitochondrial transport while expression of 36 repeats (G4C2-36) which were previously shown to cause neurotoxicity in this model, caused a decrease in the number of motile mitochondria. The glycine-alanine (GA) dipeptide repeat protein (DPR) produced by repeat-associated non-ATG (RAN) translation of the pathogenic C9orf72 GGGGCC expanded repeats has been shown to interact with Unc119, which is involved in trafficking of myristolated proteins in Caenorhabditis. It remains to be determined whether sequestration of Unc119 to GA DPRs causes axonal transport defects in mammalian neurons.

mRNP granules

TDP-43 itself is actively transported in motor neuron axons. It binds to G-quadruplex-containing mRNAs and assembles into cytoplasmic mRNP granules that undergo bidirectional axonal transport and facilitate delivery of mRNA for local translation. Pathogenic mutations in TDP-43 (M337, A315T) caused reductions in net displacements in both anterograde and retrograde directions of TDP-43 granules in transfected mouse cortical neurons and this was caused by reduced motility and increased reversal of direction. In contrast, in vivo examination of Drosophila motor axons revealed that TDP-43M337V and TDP-43A315T granules exhibited selectively impaired anterograde movement. Similarly, in stem cell-derived motor neurons from ALS patients bearing three different ALS-causing mutations in TDP-43 (G298S, A315T, M337V), TDP-43-mediated anterograde transport of NEFL mRNA was significantly decreased approximately 10 days after plating and this transport deficit progressively worsened with time in culture.

Together these data provide strong evidence for a potential involvement of defective axonal transport in disease development and/or progression long before symptom onset. Indeed, axonal transport defects are one of the earliest defects recorded in ALS, suggesting that they may be a key pathogenic event in disease.

Molecular mechanisms of axonal transport defects in ALS

The underlying cause of axonal transport defects in ALS is not fully understood. A small number of cases involve mutations in the axonal transport machinery; these cases definitively link axonal transport defects to disease. Several mechanisms by which axonal transport may be perturbed in sporadic ALS and familial ALS with mutations in non-axonal transport genes have been proposed mostly based on studies of mutant SOD1-related ALS. These include reductions in microtubule stability, mitochondrial damage, pathogenic signalling that alters phosphorylation of molecular motors to regulate their function or of cargoes such as neurofilaments to disrupt their association with motors, and protein aggregation (Table 1) (Fig. 1).

Dynein

Evidence that dysfunctional dynein/dynactin mediated axonal transport is sufficient to cause motor neuron degeneration first came to light when LaMonte et al. showed that disruption of dynein/dynactin interaction by postnatal overexpression of p50/dynamitin, a 50-kDa subunit of dynactin encoded by DCTN2, caused reduced axonal transport in motor neurons and consequently led to a late-onset progressive motor neuron disease phenotype in the transgenic mice. This was followed by several studies showing that loss-of-function mutations in DCTN1, which encodes the p150Glued subunit of the dynactin complex, cause a slowly progressive autosomal dominant distal hereditary motor neuropathy with vocal paresis (HMN7B) and ALS. The autosomal dominant G59S mutation that causes HMN7B is in the cytoskeleton-associated protein glycine-rich (CAP-Gly) domain of p150Glued (residues 48-90). This domain is involved in binding to microtubules and end binding protein 1 (EB1). The G59S mutation has been shown to reduce the binding affinity of p150Glued for microtubules, probably as a result of aberrant folding of the CAP-Gly domain and aggregation of mutant p150Glued. Interestingly these p150Glued G59S aggregates associated with mitochondria. It is not clear what the significance of this association is but it may directly or indirectly affect the axonal transport of mitochondria.

Homozygous p150Glued G59S knock-in embryos are not viable and the heterozygous mice develop late-onset MND-like phenotypes including abnormal gait, spinal motor neuron loss, increased reactive astrogliosis, and accumulation of cytoskeletal and synaptic vesicle proteins at neuromuscular junctions. A transgenic mouse model of p150Glued G59S exhibited similar phenotypes. Other disease causing autosomal dominant mutations in the CAP-Gly domain of p150Glued involve substitution of phenylalanine 52, lysine 56, glycine 71, threonine 72 or glutamine 74. Similar to the G59S mutation, the F52L and K56R mutations reduce the microtubule binding affinity of p150Glued but cause late-onset parkinsonism and frontotemporal atrophy or progressive supranuclear palsy (PSP) while residues 71, 72, and 74 which are within or close to the GKNDG microtubule binding motif of the CAP-Gly domain (residues 68–72) also reduce the binding affinity of p150Glued for microtubules but cause Perry syndrome with neuronal inclusions containing TDP-43. Other p150Glued variants including T1249I, M571T, R785W, and R1101K have been reported as possible risk factors for ALS, but further research is required to establish their role in disease. It is nonetheless clear that mutations in the DCTN1 gene cause a group of neurological disorders with overlapping clinical and/or neuronal cell pathologies.

Coinciding with the discovery that p150Glued G59S causes HMN7B, Hafezparast et al. demonstrated that single point mutations in the Dync1h1 gene, which encodes DHC, cause autosomal dominant motor function defects and motor neuron degeneration in the Legs at odd angles (Loa) and Cramping 1 (Cra1) mouse strains. The Loa and Cra1 mutations lead to F580Y and Y1055C amino acid substitutions in DHC, respectively. Heterozygous Loa and Cra1 mice display a limb grasping/clenching phenotype and a progressive movement deficit characterised by a low-based reptilian-like gait. The severity of this abnormal way of walking increases as the animals age. Heterozygous Loa mice also show a severe loss of proprioceptive sensory neurons. Homozygous Cra1 and Loa mice are not viable with Cra1 homozygosity being embryonic lethal and Loa/Loa mice die within a day after birth as a result of the loss of > 90% of their spinal cord motor neurons by E18. Cultured motor neurons isolated from Loa embryos exhibit significantly reduced retrograde axonal transport and aberrant extracellular signal-regulated kinases (ERK) 1/2 and c-Fos expression.

The F580Y mutation in DHC increases its affinity for DICs and DLICs while reducing association of dynactin to dynein. Thus, impaired transport of cargoes such as signalling endosomes which attach to dynein via dynactin may be explained by reduced dynactin-dynein interaction while reduced motor function is predicted to disturb retrograde transport more generally. Interestingly, the human variantsM581L and I584L that cause a childhood form of motor neuron disease known as spinal muscular atrophy, lower extremity-predominant 1 (SMALED1), are only 1 and 2 amino acids, respectively, from the F580Y substitution in the Loa mouse strain (; reviewed in. It is not clear why these and several other mutations within different domains of DYNC1H1 do not appear to play a more conspicuous role in the pathogenesis of ALS. One explanation could be that these mutations are pathologically detrimental to mainly long motor neurons and therefore spare other motor neuronal pools, degeneration of which tips the balance toward development of ALS.

Finally, dysregulation of transcription in a mouse model of the MND spinal and bulbar muscular atrophy (SBMA) harbouring a pathogenic expanded trinucleotide CAG repeat in the androgen receptor (AR) protein leads to reduced levels of p150Glued mRNA, which is accompanied by impaired retrograde axonal transport. Moreover, loss of TDP-43 led to decreased expression of p150Glued and impaired autophagosome-lysosome fusion, which could be rescued by transfecting the cells with p150Glued. Thus, in some cases dynein function appears to be directly affected by disease-associated downregulation of p150Glued expression.

Kinesin

As is the case for dynein, disruption of kinesin can cause neurodegeneration. Conditional knockout of Kif5a in mice caused paralysis and neurodegeneration concomitant with a reduction in neurofilament axonal transport. Similarly, disruption of Kif1a in mice led to severe motor and sensory defects and lethality within one day of birth. Kif1a knockout reduces transport of synaptic vesicle precursors and as a consequence causes decreases in synaptic vesicle density accompanied by neuronal degeneration in vivo and in cultured neurons.

Mutations in kinesin-1 or KIF1A have not directly been linked to ALS, but mutations in KIF5A and KIF1A have been identified in hereditary spastic paraplegia (HSP) forms of MND. Both KIF5A and KIF1A mutations are located in the motor or neck domains and appear to be loss-of-function variants.

α-Tubulin

Microtubules play a pivotal role in the development and maintenance of neuronal cell structures and functions and they are the essential tracks for both fast and slow long-distance axonal transport. As such, it is not surprising that perturbations in the integrity of the microtubule cytoskeleton have been linked with several neurodegenerative diseases including MND and this is exemplified by the disease-causing mutations in α-tubulin and associated proteins (reviewed in, ).

Several variants of the α-tubulin gene TUBA4A that destabilise the microtubule network and diminish its re-polymerisation capability have been identified as a possible cause of ALS. Whether these mutations affect axonal transport has not yet been determined, but since axonal transport prefers stable microtubules it is likely that they will have a detrimental effect. In this context, it is noteworthy that a missense mutation in the tubulin-specific chaperone E (Tbce) gene that causes motor neuron degeneration in the progressive motor neuronopathy (pmn) mouse strain, a model of human MND, causes microtubule loss similar to that induced by human ALS-linked TUBA4A mutations, and axonal transport defects. Finally, mutations in spastin, a microtubule severing protein, which are the most common cause of HSP impair microtubule dynamics and axonal transport of mitochondria and APP vesicles.

Pathogenic signalling as a cause of axonal transport defects

Although mutations in the molecular machinery of axonal transport unequivocally link transport defects to neurodegeneration and disease, these mutations are very rare. Nevertheless, as summarised above, axonal transport defects are a common occurrence across several models of familial ALS and have been described in sporadic ALS. In this section we summarise the possible mechanisms underlying axonal transport defects in these cases.

Microtubule stability

Microtubules are dynamic structures that may undergo assembly or disassembly by a mechanism called dynamic instability (reviewed in ). Some microtubules are more stable than others resulting in two populations referred to as labile and stable microtubules. The stability of microtubules is mainly regulated by microtubule associated proteins (MAPs) that bind along the length of the microtubule, or by capture of the plus ends by for instance protein complexes in the cell cortex. Several MAPs have been shown to stabilise microtubules in neurons, including tau, MAP2 and MAP1B. Tau, which is mainly expressed in neurons where it localises to axons, is of particular interest in the context of neurodegeneration and axonal transport. Mutations in tau have been shown to cause frontotemporal dementia with parkinsonism linked to tau mutations on chromosome 17 (FTDP-17T) and neurofibrillary tangles which mainly consist of hyperphosphorylated tau are a pathological hallmark of Alzheimer's disease (; reviewed in ). Tau has been shown to regulate the axonal transport of several cargoes, including mitochondria, possibly by regulating motor/microtubule interactions and/or by stabilising microtubules. In a further link between neurodegeneration and defective axonal transport FTD-mutant tau inhibits axonal transport. In addition, the PSP-associated R5L and R5H mutants in the N-terminal projection domain of tau disrupt its interaction with the C-terminus of p150Glued. MAP1B has been implicated in the retrograde transport of mitochondria and disruption of FUTSCH/MAP1B in Drosophila caused mitochondrial transport defects and progressive neurodegeneration. Interestingly, MAP1B mRNA is a translational target of TDP-43 and restoring its expression is protective in a Drosophila model of TDP-43-related ALS.

In addition to the labile and stable microtubule populations, a population of ultra-stable, virtually non-dynamic, so-called cold-stable microtubules have been identified. Cold-stable microtubules are enriched in axons and are made up by tubulin that has been post-translationally polyaminated. Additional tubulin modifications that have been linked to microtubule stability are α-tubulin acetylation and detyrosination, but it appears that these modifications accumulate on longer-lived more stable microtubules rather than stabilise microtubules per se. Hence the presence of acetylated or detyrosinated α-tubulin is a marker for stable microtubules. Post-translational tubulin modifications have been linked to regulation of kinesin-1 mediated axonal transport. Thus, kinesin-1 appears to preferentially bind to acetylated and/or detyrosinated microtubules. Microtubule acetylation has been shown to stimulate kinesin-1-mediated transport, while tubulin detyrosination appears to direct kinesin-1 to the axon. If and how post-translational modifications of tubulin affect dynein-mediated transport is less clear, but increasing α-tubulin acetylation has been shown to cause recruitment of dynein to microtubules and in case of axonemal dynein, microtubule acetylation increased motility. Microtubule acetylation occurs primarily on the epsilon amino group of the lysine at position 40 (K40) of α-tubulin by α-tubulin acetyl transferase 1 (αTAT1, also known as MEC17), and deacetylation is mediated by histone deacetylase 6 (HDAC6) and Sirtuin-2 (SIRT2). Interestingly loss of TDP-43 or FUS has been shown to reduce HDAC6 expression, suggesting that ALS-associated TDP-43 and FUS dysfunction may affect axonal transport via changes to microtubule acetylation.

Measurement of in vivo microtubule polymerisation/depolymerisation rates using mass spectrometry analysis of 2H2O-labelled tubulin revealed an increase in microtubule dynamics in presymptomatic SOD1G93A transgenic mice, which correlated with impaired slow axonal transport and progressively increased with disease. In addition, hyperdynamic microtubule subpopulations were found in the lumbar segment of the spinal cord (where motor neuron pathology occurs) and cerebral cortex, and in the peripheral motor and sciatic mixed nerves, but not in sensory nerves. Direct identification of dynamic microtubules by live imaging of EB3-YFP also identified increased microtubule dynamics in intercostal axons of Thy1:EB3-YFP–SOD1G93A and G85R transgenic mice.

Mutant SOD1A4V, G85R and G93A but not wild type SOD1 have been shown to interact with tubulin and to affect microtubule stability in vitro, providing a possible explanation for decreased microtubule stability in vivo. Alternatively, mutant SOD1-associated reductions in microtubule stability may involve excitotoxicity-related increases in intracellular calcium levels (reviewed in ) that induce depolymerisation of microtubules, or oxidative stress (reviewed in ), which has been shown to affect microtubule stability, albeit in non-neuronal cells. Further insults may involve changes to MAPs. MAP2, MAP1A, and tau levels are reported to be reduced in the spinal cord of pre-symptomatic SOD1G37R transgenic mice, and tau hyperphosphorylation, which is predicted to reduce tau binding to microtubules and hence lower microtubule stability was reported in the same mouse model.

Indications that microtubule stability may also be affected in sporadic ALS come from the observation that in post-mortem spinal cord and brain tissue sections of sporadic ALS cases hyperphosphorylated NF-H positive spheroids also show positive staining for microtubule associated protein 6 (MAP6). MAP6, which is also known as stable tubule only polypeptide (STOP), protects microtubules from cold-induced depolymerisation and is preferentially associated with stable microtubules in neurons. Its abnormal accumulation in the spheroids suggest disruption of stable microtubules and consequently disrupted transport, which may be a contributory factor in sporadic ALS. Interestingly MAP6 also interacts with TMEM106B, a major risk factor of frontotemporal dementia (FTD) and a modifier of C9orf72-associated ALS and FTD that is involved in axonal transport of lysosomes. Finally, a reduction in the levels of acetylated tubulin has been linked to axonal instability and axonal transport defects in familial ALS (ALS5) and HSP (SPG11) caused by mutations is spatacsin.

Mitochondrial damage

Mitochondria play a pivotal role in many cellular events including energy metabolism and calcium handling. The latter is of special importance for motor neurons that rely greatly on mitochondria for calcium buffering (reviewed in ). Furthermore, calcium handling and ATP production by mitochondria are intimately linked because mitochondrial calcium activates the rate-limiting enzymes of the Krebs cycle and thereby increases oxidative phosphorylation and ATP synthesis to match local energy demand. Evidence suggests that both reduced mitochondrial energy metabolism and dysfunctional calcium handling are likely to be main contributors to the axonal transport defects observed in ALS. Moreover, it is likely that impaired transport of mitochondria themselves and concomitant depletion of mitochondria from axons further exacerbates any defects.

Damage to mitochondria is a well-documented, early phenomenon in ALS (reviewed in,, ). In SOD1 or TDP-43-associated familial ALS mitochondrial damage appears to be directly linked to pathological accumulations of aggregated ALS mutant SOD1 or TDP-43 in mitochondria. Whether aggregated TDP-43 also accumulates in mitochondria in sporadic ALS is not yet clear. ALS mutant SOD1 has been shown to specifically interact with spinal cord mitochondria via direct interaction with voltage-dependent anion channel 1 (VDAC1) and this accumulation is sufficient and necessary to damage mitochondria. Accumulation of ALS mutant TDP-43 in mitochondria appears to be mediated by internal mitochondrial targeting sequences in TDP-43. Mutant SOD1 and TDP-43-mediated damage to mitochondria is believed to severely impair the mitochondrial electron transfer chain and ATP synthesis. Overexpression of FUS has been shown to reduce mitochondrial ATP production, but whether ALS mutant FUS accumulates in mitochondria is not clear. Mutations in the mitochondrial protein CHCHD10 have been shown to cause familial ALS. CHCHD10 is localised to contact sites between the inner and outer mitochondrial membrane and mutations disrupt mitochondrial cristae and impair mitochondrial genome maintenance. It is not clear if CHCHD10 mutants directly affect mitochondrial function, but since assembly and maintenance of the mitochondrial electron transport chain relies on intact cristae and mitochondrial encoded subunits, it is likely that they do. Indeed, disruption of cristae by mitofilin depletion disrupts mitochondrial function and reduces mitochondrial membrane potential and ATP levels. In agreement, respiratory chain complex I, III and IV deficiency was identified in fibroblasts of a CHCHD10 patient.

In addition to decreased ATP production, damage to mitochondria has been associated with the disrupted calcium homeostasis observed in in vitro and in vivo models of mutant SOD1, VAPB, TDP-43, and FUS-related ALS. Compelling evidence suggests that disrupted calcium homeostasis is caused by dysfunctional communication between the endoplasmic reticulum (ER) and mitochondria at mitochondria-associated ER membranes (MAM). Reduced ER/mitochondria contact sites have been observed in mutant SOD1, SIGMAR1, TDP-43, and FUS-related ALS. In contrast overexpression of ALS mutant VAPBP56S increased ER/mitochondria contacts, but since in ALS8 patient-derived iPSC neurons VAPB expression is down-regulated because of reduced expression of the VAPBP56S mutant, it is likely that in VAPBP65S-related ALS ER/mitochondria contacts are actually decreased as well. ER interacts with mitochondria via tethering proteins (reviewed in ), such as the ER protein VAPB that binds to the mitochondrial outer membrane protein PTPIP51. In case of mutant TDP-43 and FUS the reduction in ER/mitochondria contact was the direct result of decreased binding of VAPB to PTPIP51. If this is also the case in mutant SOD1 and SIGMAR1-related ALS remains to be determined. Interestingly, the levels of VAPB are reduced in the spinal cord of sporadic ALS cases, suggesting that disrupted ER-mitochondria communication could be a general feature in ALS and that restoring ER/mitochondria contact may be of therapeutic benefit. In agreement with this, neuronal overexpression of wild-type human VAPB has been shown to slow disease and increase survival in SOD1G93A transgenic mice.

The outer mitochondrial membrane protein Miro1 has emerged as the main regulator of axonal transport of mitochondria although the remaining transport of mitochondria in Miro1 knockout neurons suggests that at least some mitochondrial transport is Miro1 independent. Possibly Miro2 can partly compensate for the loss of Miro1. Kinesin-1 connects to mitochondria through interaction with Miro1 via the adaptor proteins TRAK1 and 2, and dynein has been shown to interact with both Miro1 and TRAK1/2. The Miro1/TRAK1 complex further associates with disrupted in schizophrenia 1 (DISC1) and this has been linked to regulation of anterograde mitochondrial transport, possibly via interaction with the anchoring protein syntaphilin or NDE1 and glycogen synthase kinase 3β (GSK3β) or by regulating mitochondrial bioenergetics via interaction with mitofilin and the mitochondrial contact site and cristae organising system (MICOS) complex.

Miro1 is an atypical Rho GTPase comprised of two GTPase domains separated by two calcium-binding E-helix-loop-F-helix (EF)-hand motifs, and is anchored in the mitochondrial outer membrane by a C-terminal transmembrane domain. Miro1 plays a central role in the regulation of mitochondrial axonal transport in response to calcium and mitochondrial damage.

Binding of calcium to the Miro EF-hand motifs halts anterograde transport of mitochondria by regulating the interaction of kinesin-1 with Miro1 such that either kinesin-1 binding to microtubules or to Miro1 is disrupted and this appears an important mechanism to regulate mitochondrial transport in response to physiological stimuli. Increased cytosolic calcium levels have been reported in cellular models and in motor neurons from transgenic ALS models and have been shown to disrupt transport of mitochondria via Miro1 in VAPBP56S-expressing neurons.

In mitophagy, loss of mitochondrial membrane potential or accumulation of misfolded proteins in mitochondria, leads to the stabilisation and activation of the Ser/Thr kinase PINK1 on the outer mitochondrial membrane. PINK1 subsequently phosphorylates ubiquitin on Ser65 which drives recruitment of the cytosolic E3 ubiquitin ligase Parkin to damaged mitochondria. PINK1 further phosphorylates Parkin leading to its full activation. PINK1 also forms a complex with Miro1 and TRAK and phosphorylates Miro1 in response to mitochondrial damage. Phosphorylated Miro is targeted for proteasomal degradation in a Parkin-dependent manner and as a result kinesin-1 detaches from the mitochondrial surface and mitochondrial movement is arrested. In addition, Parkin ubiquitinates other outer mitochondrial membrane substrates, such as mitofusin, to isolate the damaged mitochondria and to recruit autophagy receptors such as NDP52, optineurin (both substrates of TANK-binding kinase (TBK1)) and p62 to deliver the damaged mitochondria to autophagosomes. Interestingly loss-of-function mutations in optineurin, p62 and TBK1 have been shown to cause ALS, and the C9orf72 protein regulates autophagy and interacts with SMCR8 which is itself a TBK1 substrate. In agreement with ALS-associated mitochondrial damage leading to PINK1/Parkin-mediated halting of mitochondrial transport, decreased levels of Miro1 have been reported in SOD1G93A and TDP-43M337V transgenic mice as well as in the spinal cord of ALS patients while down-regulation of either PINK1 or Parkin partially rescued the locomotive defects and enhanced the survival rate in transgenic flies expressing FUS. Interestingly mitochondria remained homogeneously distributed throughout the axons of Miro1 knockout neurons despite a 65% decrease in trafficking. This is reminiscent of the situation in SOD1G93A expressing neurons where reduced anterograde transport and the resulting loss of axonal mitochondria did not translate into changes in the overall distribution of mitochondria in the axon, but rather caused a compensatory increase in inter-mitochondrial distance.

Whether mitochondrial axonal transport defects are part of all ALS is not yet clear, but mitochondrial damage, dysfunctional calcium metabolism and reduced expression of Miro1 have been found in sporadic ALS cases. Furthermore, energy defects and reduced calcium buffering capacity caused by reduced numbers of mitochondria in the distal axon, exacerbated by mitochondrial and MAM dysfunction, may explain the selective vulnerability of motor neurons because they are particularly reliant on mitochondria for calcium buffering as a consequence of their relative lack of cytosolic calcium binding proteins. One obvious way in which mitochondrial damage and concomitant mitochondrial transport defects and depletion of mitochondria from axons could affect the transport of other cargoes such as APP vesicles or signalling endosomes is by starving molecular motors of ATP. However, since it has been shown that neuronal BDNF, APP, and TrkB vesicles harbour most glycolytic enzymes and “self-propel” using their own source of glycolytic ATP independent of mitochondria reduced axonal mitochondrial ATP production may not be sufficient to halt axonal transport. Alternatively, mitochondrial damage and/or lack of axonal mitochondria may affect transport by disturbance of calcium signalling. Indeed, MAP6’s microtubule stabilisation activity is regulated by calcium/calmodulin. Increased calcium is associated with increased MAP6/calmodulin interaction and reduced microtubule binding. Hence increases in cytosolic calcium caused by mitochondrial dysfunction could destabilise microtubules and consequently impair axonal transport.

Kinase signalling

Axonal transport is regulated by phosphorylation (reviewed in ). Direct phosphorylation of molecular motors has been shown to affect motor activity and phosphorylation of adapter proteins and cargoes has been shown to affect attachment of motors to cargo. Furthermore, phosphorylation of MAPs has been shown to regulate microtubule stability and hence axonal transport. Several of the kinases involved in the regulation of axonal transport have been associated with ALS.

p38 MAP kinase

A number of groups have shown that p38 mitogen-activated protein (MAP) kinase is overactivated in the spinal cord of SOD1G93A transgenic mice and in familial and sporadic human ALS cases. Although the precise role of p38 MAP kinase in disease is not fully understood, inhibition of p38 MAP kinase protected mutant SOD1 expressing motor neurons in vitro and in vivo in SOD1G93A transgenic mice, suggesting an active role in the neuropathology of disease. The activation of p38 MAP kinase probably involves excitotoxic glutamate signalling and protein stress by for example misfolded SOD1.

p38 MAP kinase has been shown to phosphorylate kinesin-1 on serines 175 and 176 and this inhibited translocation of kinesin-1 along axonal microtubules while p38 MAP kinase phosphorylation of KLC inhibited anterograde transport of mitochondria. p38 MAP kinase also phosphorylates neurofilament medium polypeptide (NF-M)/NF-H sidearms which slows their transport, probably by reducing neurofilament binding to molecular motors. Supporting a role for p38 MAP kinase in neurofilament pathology, increased co-localisation of p38 MAP kinase and phosphorylated neurofilaments was observed in degenerating neurons at the onset of disease in SOD1G93A transgenic mice. Interestingly, the anti-glutamatergic drug riluzole, currently the only approved drug for the treatment of ALS, has been shown to prevent p38 MAP kinase activation by excitotoxic glutamate and restore axonal transport of neurofilaments.

Using a monoclonal antibody to misfolded SOD1 (C4F6), revealed the presence of a misfolded wild-type SOD1 in post-mortem human spinal cord tissues of 4 out of 9 sporadic ALS cases. Misfolded wild-type SOD1 purified from sporadic ALS tissues inhibited anterograde axonal transport in isolated squid axoplasm assays to the same extend as a familial ALS-associated SOD1H46R mutant, and this was found to involve the activation of p38 MAP kinase and subsequent kinesin-1 phosphorylation. A later study using YFP-tagged SOD1G85R revealed that Hsc70 and its nucleotide exchange factor Hsp110 prevented SOD1G85R-induced activation of p38 MAP kinase and the transport defect exerted by mutant SOD1G85R, possibly by enhancing disaggregation of SOD1. Interestingly, overexpression of Hsp110 has been shown to markedly increase the life span of YFP-SOD1G85R and SOD1G93A transgenic mice.

JNK

JNK/c-Jun signalling has been implicated in TDP-43 induced protein toxicity, and increased amounts of phosphorylated c-Jun have been reported in SOD1G93A transgenic mice. The latter appears to correlate with an increase in retrograde JNK signalling rather than overall increased activation of JNK in motor neurons. JNK has also been shown to be activated by glutamate excitotoxicity but if this is the case in ALS is not clear. Indeed,, did not find JNK activation in motor neurons and microglia from SOD1G93A transgenic mice.

JNK has been shown to modulate both kinesin/microtubule and kinesin/cargo interactions. The former has been linked to JNK-mediated phosphorylation of the kinesin-1 motor domain whereas the latter involves disruption of the binding of the cargo adapter JIP1 to kinesin-1. JNK also interacts with dynein via binding of JIP3 to p150Glued and DLIC and this is required for retrograde transport of activated JNK. Whether activated JNK regulates its own retrograde transport is not yet clear. Activated JNK may also have a general effect on axonal transport by regulation of Dishevelled-mediated microtubule stability. Changes to the WNT signalling pathway have been described in ALS but if these affect microtubules remains to be determined. As was the case for p38 MAP kinase, JNK activation has been linked to misfolded protein stress. Neuropathogenic forms of huntingtin and AR were shown to inhibit axonal transport and subsequent studies showed that this inhibition is JNK mediated. Finally, JNK also phosphorylates NF-M/NF-H sidearms.

Overactivation of GSK3β has been reported in the brain and spinal cord of SOD1G93A transgenic mice and spinal cord samples from sporadic ALS patients. Nevertheless, the involvement of GSK3β in ALS remains controversial. Inhibition of GSK3β was protective in SOD1G93A transgenic mice in some studies but not in others Moreover, lithium, a known inhibitor of GSK3β, did not show any evidence of benefit on survival in patients with ALS.

GSK3β

GSK3β negatively regulates axonal transport in a number of ways. GSK3β-mediated phosphorylation of KLC2 has been shown to release kinesin-1 from vesicles in a regulatory pathway that involves Cyclin-dependent kinase 5 (Cdk5) (see below), lemur tyrosine kinase 2 (LMTK2) and protein phosphatase 1 (PP1). Phosphorylation of DIC1B and DIC2C by GSK3β inhibited retrograde transport of acidic organelles by reducing the binding of NDEL1 to DICs. Furthermore, GSK-3β-dependent phosphorylation of the motor adapter BICD1 is required for its binding to dynein. Since NDEL1, LIS1 and BICD are involved in regulation of dynein function, GSK3β may be affecting multiple retrograde cargoes and this may explain the defects in retrograde transport reported in ALS. NDE1, LIS1 and GSK3β have also been shown to interact with TRAK1 and this interaction is involved in regulating axonal transport of mitochondria. Overexpression of NDE1 increased retrograde transport of mitochondria, while activation of GSK3β stimulated anterograde transport. Consistent with NDE1/LIS1 regulation of mitochondrial transport it was shown that reducing the levels of LIS1 increases mitochondrial trafficking in adult Drosophila neurons. Interestingly mutations in LIS1, NDE1 and BICD2 have all been associated with neurodegeneration.

GSK3β is a major tau kinase involved in neurodegeneration (reviewed in, ). Phosphorylation of tau by GSK3β releases tau from microtubules and destabilises microtubules which can disrupt axonal transport. ALS-associated defects in ER/mitochondria communication are linked to activation of GSK3β. Thus, GSK3β may also indirectly regulate axonal transport by affecting ER/mitochondria communication as described above. GSK3β has also been described as a neurofilament kinase that affects anterograde neurofilament transport by regulating neurofilament bundling.

Cdk5

Cdk5 is a member of the cyclin-dependent kinase family expressed in post-mitotic cells including neurons. Under normal circumstances Cdk5 is activated by p35, which in turn is phosphorylated by Cdk5 leading to its degradation by the proteasome and subsequent inactivation of Cdk5. Under stress conditions p35 is cleaved by calpain to generate a p25 fragment which retains its Cdk5 activation activity, but lacks the regulatory phosphorylation site, leading to sustained activation of Cdk5 and this has been linked to neurodegeneration. Transgenic overexpression of p25 in neurons caused MND reminiscent of ALS and aberrant activation of Cdk5 has been reported in the spinal cord of mouse models of ALS. Consistent with a possible role of p25 dependent overactivation of Cdk5 in ALS, overexpression of the endogenous calpain inhibitor calpastatin delayed disease onset and increased survival of SOD1G93A transgenic mice. However, since genetic ablation of the Cdk5 activator p35 did not affect the onset and progression of motor neuron disease in SOD1G93A transgenic mice, the protective effect of calpastatin may actually derive from its inhibition of MAP2 and neurofilament proteolysis. Cdk5 has been shown to phosphorylate neurofilaments and this regulates their transport. Cdk5 also regulates anterograde trafficking of vesicles by activating GSK3β and by phosphorylation of NDEL1 Cdk5 inhibits dynein-mediated transport of lysosomes, autophagosomes, mitochondria, and signalling endosomes. Interestingly inactivation of Cdk5 with roscovitine rescued defective retrograde transport of TrkB vesicles in DRG neurons cultured from 90- to 100-day-old SOD1G93A transgenic mice.

Protein aggregation

Protein misfolding and aggregation is a hallmark pathology of ALS (reviewed in ). TDP-43 aggregates are found in almost all ALS cases, including sporadic cases and most familial ALS cases. ALS patients with SOD1 mutations are a notable exception but do however exhibit aggregated mutant SOD1 in affected neurons. Other familial ALS associated mutant proteins that are prone to aggregation are TDP-43 itself, FUS, and the DPRs generated by RAN translation of the expanded G4C2 repeats in C9orf72. Furthermore, a number of familial ALS-associated proteins are known to be involved in protein quality control mechanisms, including C9orf72, valosin-containing protein (VCP), sequestosome-1/p62, ubiquilin-2, optineurin, dynactin, and TBK1 (reviewed in ).

As discussed above, misfolded SOD1 disrupts anterograde transport by activation of p38 MAP kinase. In addition, dynein has been shown to interact with ALS-mutant SOD1A4V, G85R, and G93A but not wild type SOD1 via DIC. Moreover dynein and ALS mutant SOD1 appeared to mostly colocalise in ALS mutant SOD1 protein aggregates in cultured motor neurons and in vivo in SOD1G93A and G85R transgenic mice supporting the notion that reduced retrograde axonal transport in SOD1-related ALS may at least in part be caused by sequestration of dynein. It is not clear if any of the other misfolded proteins associated with ALS disrupt transport in a similar fashion.

In addition to TDP-43 aggregates, accumulations of neurofilaments and peripherin in axonal spheroids and motor neuron cell bodies are a pathological hallmark of ALS (reviewed in, ). As described above aberrant phosphorylation of neurofilaments appears to play a major role in the dysregulation of their transport and in the formation of these pathological inclusions. It has been suggested that accumulation of neurofilaments may also affect the transport of other cargoes. Indeed, changes in neurofilament organisation due to loss of neurofilament light polypeptide (NF-L) in peripherin overexpressing cells disrupted transport of mitochondria. Interestingly, peripherin upregulation in combination with NF-L downregulation was also found in the spinal cord of TDP-43G348C and A315T transgenic mice. This may be due to TDP-43 mediated regulation of neurofilament and peripherin mRNA processing. How neurofilament accumulations disrupt transport is not entirely resolved but may involve blockage of the axon or disruption of the microtubule network. Indeed, neurofilament depletion caused a stabilisation of microtubules in pmn mutant motor neurons by reducing the sequestration of Stat3/stathmin to neurofilaments.

Non-cell autonomous toxicity

Although the selective degeneration of motor neurons defines ALS, it is now clear that non-neuronal cells in the CNS such as astrocytes, microglia, and oligodendrocytes do contribute to disease. How these non-neuronal CNS cells contribute to neurodegeneration is still under debate, but may involve reduced metabolic support, release of cytokines and toxins, and glutamate excitotoxicity (reviewed in ). Activated microglia-conditioned medium has been shown to induce neuritic beading in cultured motor neurons via N-methyl-d-aspartate (NMDA) receptor signalling. NMDA-signalling mediated inhibition of mitochondrial complex IV and a subsequent decline in ATP levels reduced fast axonal transport and led to abnormal accumulation of tubulin, neurofilament, kinesin and dynein in the spheroids prior to the death of the motor neurons. Thus, these data suggest a link between the non-cell autonomous toxicity ALS and a downstream disruption of fast axonal transport. Similarly, expression of a mutant AR transgene solely in skeletal muscle fibres caused an androgen-dependent motor neuron degeneration and a SBMA phenotype, including defects in retrograde transport.

Restoring transport as a treatment for ALS?

As discussed above, axonal transport defects are part of ALS neuropathology. Axonal transport defects are one of the earliest insults observed in ALS, arguing that they may be causative for disease. Genetic evidence showing that mutations in molecular motors and microtubules are sufficient to cause ALS and ALS-related motor neuron disorders, confirms that axonal transport defects can cause neurodegeneration. Thus, the question arises if restoring axonal transport may be of therapeutic benefit in ALS patients. The emerging insight in the molecular mechanisms underlying axonal transport defects in ALS reviewed above has allowed to devise strategies to restore transport and to begin to answer this question (Table 2).

Restoration of mitochondrial transport

Defects in axonal transport of mitochondria are a robust finding in ALS, and because they are observed as early as at embryonic stage in ALS mouse models mitochondrial transport defects have been proposed to play an important role in disease. However, increasing axonal motility of mitochondria in SOD1G93A transgenic mice by depletion of the mitochondrial docking protein syntaphilin did not alter the course of disease in SOD1G93A transgenic mice. It has to be noted that Zhu et al., only verified increased axonal transport in DRG neurons which are not a target of ALS, but it is perhaps not surprising that restoring transport of damaged mitochondria does not affect the disease process. Indeed, the robust reduction in anterograde transport of mitochondria following ALS-associated damage may be indicative of increased clearance of mitochondria by mitophagy. Nevertheless, these findings suggest that impairment of mitochondrial transport may not be a primary cause of motor neuron degeneration and that any strategy to improve transport may need to be combined with drugs targeting mitochondrial dysfunction.

Restoration of endosomal trafficking

It is possible that disrupted transport of another cargo than mitochondria is essential for motor neuron survival. One such cargo may be BDNF/TrkB signalling endosomes that are retrogradely transported toward the soma (reviewed in ). Indeed, targeted disruption of retrograde transport causes ALS-like disease in a number of models (see above) and BDNF is known to support motor neurons in vitro and in vivo (; reviewed in ).

In line with this possibility the unexpected amelioration in disease progression observed in SOD1G93A transgenic mice crossed with Loa mice was accompanied by a full rescue of the axonal transport of signalling endosomes. The protective effect of the Loa mutation in dynein potentially relates to reductions in mitochondrial damage and associated axonal transport defects in SOD1G93A–Loa/+ mice. Indeed, the amount of mitochondria-associated mutant SOD1 protein was markedly reduced in SOD1G93A–Loa/+ mice and this correlated with improvements in mitochondrial respiration and membrane potential in SOD1G93A–Loa/+ motor neurons. Mutant SOD1 has been shown to interact with dynein and this interaction was critical for the formation of SOD1 aggregates. Hence a possible explanation for the restoration of endosome trafficking in SOD1G93A–Loa/+ mice is that reduced interaction of mutant SOD1 with Loa dynein restores transport of retrograde cargoes and that concomitant reductions in mutant SOD1 aggregates that are damaging to mitochondria restore mitochondrial function and possibly transport.

Overexpression of BICD2-N, which chronically impairs dynein/dynactin function, also delayed disease onset and increased life span of ‘low-copy’ SOD1G93A transgenic mice by 14%. Possibly, in this case reduced transport of signalling endosomes may dampen the effects of a switch in retrograde signalling from survival to stress in SOD1G93A–Loa/+ transgenic mice.

Targeting microtubules to restore transport

Microtubules are emerging as an attractive target to modulate axonal transport with several laboratories reporting beneficial effects of microtubule-binding drugs that were originally developed as antimitotic agents for the treatment of cancer (reviewed in ). Treatment of SOD1G93A transgenic mice with noscapine, which attenuates microtubule dynamics, partially stabilised microtubules and delayed onset of disease compared to the untreated SOD1G93A transgenic mice and this effect increased when administered in combination with the anti-inflammatory PPARgamma agonist pioglitazone. Interestingly pioglitazone treatment per se also stabilised hyperdynamic microtubules. Similarly, low doses of noscapine rescued peroxisome trafficking defects in HSP patient-derived olfactory neurosphere-derived cells and this correlated with a restoration of acetylated microtubules in these cells. In the same study, taxol, vinblastine and epothilone were reported to have a beneficial effect similar to that of noscapine. While both taxol and epothilone are known to stabilise microtubules, vinblastine is a microtubule-destabilising agent. However, it is likely that at the low doses used vinblastine attenuates microtubule dynamics rather than causes depolymerisation. If these drugs have a beneficial effect on axonal transport, axonal swellings and gait abnormalities in HSP models such as Spast∆ E7/∆E7 or Sp∆/∆ mice remains to be determined, but epothilone also has shown beneficial effects in models of Alzheimer's disease and Parkinson's disease and was in a clinical phase I trial for Alzheimer's disease (ClinicalTrials.gov NCT01492374).

Following a report that microtubule acetylation increased kinesin-1 mediated transport several laboratories have explored the beneficial effects of acetylation enhancing drugs on axonal transport and neurodegeneration. Most of these studies have focussed on inhibition of the tubulin deacetylases HDAC6 and SIRT2, although the role of SIRT2 in mouse CNS remains questionable. For example, HDAC6 inhibition compensated for axonal transport defects in Huntington's disease, reversed axonal loss in vivo in mutant HSPB1-induced Charcot-Marie-Tooth disease, and restored axonal transport and locomotor defects in a Drosophila model of mutant LRRK2-associated Parkinson's disease while loss of HDAC6 rendered neurons resistant to amyloid-β-mediated impairment of mitochondrial trafficking and rescued memory function in APPPS1-21 transgenic Alzheimer's disease mice. Genetic ablation of HDAC6 in SOD1G93A transgenic mice significantly extended the survival without affecting the timing of disease onset. Deletion of HDAC6 increased levels of acetylated tubulin, but it is not clear if this restored the axonal transport defects reported in this mouse model. Although microtubule acetylation appears to be an attractive target, a possible caveat of long-term HDAC6 inhibition is that HDAC6 also plays a critical role in the clearance of aggregated proteins by autophagy (aggrephagy) and has been implicated in clearance of mutant SOD1.

Targeting kinases to restore transport

A number of studies have targeted kinases involved in the regulation of axonal transport. Inhibition of p38 MAPK kinase protected motor neurons but only modestly prolonged survival in SOD1G93A transgenic mice. Similarly, inhibition of Cdk5 by overexpression of calpastatin delayed disease onset and increased survival of SOD1G93A transgenic mice. Inhibition of GSK3β was found to be protective in SOD1G93A transgenic mice. Although these studies reported benefits, none analysed axonal transport so it remains to be seen if restoration of axonal transport exerts the beneficial effects observed. Moreover, since genetic ablation of the Cdk5 activator p35 did not affect the onset and progression of motor neuron disease in SOD1G93A transgenic mice, and some studies found no effects of GSK3β inhibition it is clear that further confirmation is required.

Conclusions

The link between axonal transport defects and ALS and other neurodegenerative diseases is very strong and over the past two decades our understanding of axonal transport defects has increased considerably. Nevertheless, there are still large gaps in our knowledge with regards to this link. For example, how do mutations in the same motors cause different neurodegenerative diseases, or why do they specifically target neurons, and often one type of neurons but not others in the same person? One explanation is the unique geometry and/or physiology of neurons renders them selectively vulnerable to insults to the transport system. As discussed above, in case of motor neurons, increased susceptibility may derive from their particular reliance on mitochondria for calcium buffering. In this scenario, mitochondrial damage combined with reduced numbers of axonal mitochondria due to defective axonal transport disrupts calcium homeostasis which in turn leads to reduced microtubule stability, impaired binding of motor proteins to the microtubules, and defective axonal transport which then exacerbates calcium dysfunction in a vicious circle. An alternative explanation may be disruption to motor neuron specific retrograde signalling pathways. However, while in ALS motor neurons exhibit the earliest signs of pathology and the highest vulnerability, there is clear evidence of pathological lesions outside the motor system. Moreover it is clear that non-neuronal cells play an important role in disease as well. Hence the apparent motor neuron specificity of ALS-associated insults such as transport deficits is relative.

Another important question is whether restoring axonal transport is sufficient to cure neurodegenerative diseases. In case of transport defects caused by mutations in the axonal transport machinery the answer to that question is probably yes and maybe gene therapy holds the future for those cases. In other cases, the answer is less clear-cut. It seems most likely that restoring axonal transport will not be a magic bullet treatment but will be of benefit in combination with other treatments targeting the diverse cellular mechanism associated with disease such as protein aggregation and mitochondrial damage. Indeed, the widespread and early nature of axonal transport defects in ALS suggests that these defects will have to be addressed if treatment is to be effective. Further efforts to standardise the measurement and analysis of axonal transport and to develop non-invasive methods to quantify axonal transport in vivo in animal models and in patients, as well as further research into the molecular mechanisms underlying axonal transport defects will be needed if we are to develop and validate treatments that target axonal transport.

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    Bettencourt da Cruz A., Schwärzel M., Schulze S., Niyyati M., Heisenberg M., Kretzschmar D. Disruption of the MAP1B-related protein FUTSCH leads to changes in the neuronal cytoskeleton, axonal transport defects, and progressive neurodegeneration in Drosophila. Mol. Biol. Cell. 2005;16:2433-2442.

    Not in our library10.1091/mbc.e04-11-1004

  21. 21.

    Bian F., Nath R., Sobocinski G., Booher R.N., Lipinski W.J., Callahan M.J., Pack A., Wang K.K., Walker L.C. Axonopathy, tau abnormalities, and dyskinesia, but no neurofibrillary tangles in p25-transgenic mice. J. Comp. Neurol. 2002;446:257-266.

    Not in our library10.1002/cne.10186

  22. 22.

    Bilsland L.G., Sahai E., Kelly G., Golding M., Greensmith L., Schiavo G. Deficits in axonal transport precede ALS symptoms in vivo. Proc. Natl. Acad. Sci. U. S. A. 2010;107:20523-20528.

    Not in our library10.1073/pnas.1006869107

  23. 23.

    Black M.M. Axonal transport: the orderly motion of axonal structures. Methods Cell Biol. 2016;131:1-19.

    Not in our library10.1016/bs.mcb.2015.06.001

  24. 24.

    van Blitterswijk M. TMEM106B protects C9ORF72 expansion carriers against frontotemporal dementia. Acta Neuropathol. 2014;127:397-406.

    Not in our library10.1007/s00401-013-1240-4

  25. 25.
  26. 26.

    Bommel H., Xie G., Rossoll W., Wiese S., Jablonka S., Boehm T., Sendtner M. Missense mutation in the tubulin-specific chaperone E (Tbce) gene in the mouse mutant progressive motor neuronopathy, a model of human motoneuron disease. J. Cell Biol. 2002;159:563-569.

    Not in our library10.1083/jcb.200208001

  27. 27.

    Bosco D.A. Wild-type and mutant SOD1 share an aberrant conformation and a common pathogenic pathway in ALS. Nat. Neurosci. 2010;13:1396-1403.

    Not in our library10.1038/nn.2660

  28. 28.

    Bozzo F., Mirra A., Carrì M.T. Oxidative stress and mitochondrial damage in the pathogenesis of ALS: new perspectives. Neurosci. Lett. 2016;636:3-8.

    Not in our library10.1016/j.neulet.2016.04.065

  29. 29.

    Brickley K., Stephenson F.A. Trafficking kinesin protein (TRAK)-mediated transport of mitochondria in axons of hippocampal neurons. J. Biol. Chem. 2011;286:18079-18092.

    Not in our library10.1074/jbc.m111.236018

  30. 30.

    Brickley K., Smith M.J., Beck M., Stephenson F.A. GRIF-1 and OIP106, members of a novel gene family of coiled-coil domain proteins: association in vivo and in vitro with kinesin. J. Biol. Chem. 2005;280:14723-14732.

    Not in our library10.1074/jbc.m409095200

  31. 31.

    Bruijn L.I. ALS-linked SOD1 mutant G85R mediates damage to astrocytes and promotes rapidly progressive disease with SOD1-containing inclusions. Neuron. 1997;18:327-338.

    Not in our library10.1016/s0896-6273(00)80272-x

  32. 32.

    Brunden K.R. Epothilone D improves microtubule density, axonal integrity, and cognition in a transgenic mouse model of tauopathy. J. Neurosci. 2010;30:13861-13866.

    Not in our library10.1523/jneurosci.3059-10.2010

  33. 33.
  34. 34.

    Carrì M.T., Ferri A., Battistoni A., Famhy L., Gabbianelli R., Poccia F., Rotilio G. Expression of a Cu,Zn superoxide dismutase typical of familial amyotrophic lateral sclerosis induces mitochondrial alteration and increase of cytosolic Ca2 + concentration in transfected neuroblastoma SH-SY5Y cells. FEBS Lett. 1997;414:365-368.

    Not in our library10.1016/s0014-5793(97)01051-x

  35. 35.

    Carrì M.T., D'Ambrosi N., Cozzolino M. Pathways to mitochondrial dysfunction in ALS pathogenesis. Biochem. Biophys. Res. Commun. 2016.

    Not in our library10.1016/j.bbrc.2016.07.055

  36. 36.

    Cartelli D. Microtubule alterations occur early in experimental parkinsonism and the microtubule stabilizer epothilone D is neuroprotective. Sci. Report. 2013;3:1837.

    Not in our library10.1038/srep01837

  37. 37.

    Cavalli V., Kujala P., Klumperman J., Goldstein L.S. Sunday Driver links axonal transport to damage signaling. J. Cell Biol. 2005;168:775-787.

    Not in our library10.1083/jcb.200410136

  38. 38.

    Chen R.W., Qin Z.H., Ren M., Kanai H., Chalecka-Franaszek E., Leeds P., Chuang D.M. Regulation of c-Jun N-terminal kinase, p38 kinase and AP-1 DNA binding in cultured brain neurons: roles in glutamate excitotoxicity and lithium neuroprotection. J. Neurochem. 2003;84:566-575.

    Not in our library10.1046/j.1471-4159.2003.01548.x

  39. 39.

    Chen X.J., Levedakou E.N., Millen K.J., Wollmann R.L., Soliven B., Popko B. Proprioceptive sensory neuropathy in mice with a mutation in the dynein heavy chain 1 gene. J. Neurosci. 2007;27:14515-14524.

    Not in our library10.1523/jneurosci.4338-07.2007

  40. 40.

    Chen Y., Guan Y., Liu H., Wu X., Yu L., Wang S., Zhao C., Du H., Wang X. Activation of the Wnt/β-catenin signaling pathway is associated with glial proliferation in the adult spinal cord of ALS transgenic mice. Biochem. Biophys. Res. Commun. 2012;420:397-403.

    Not in our library10.1016/j.bbrc.2012.03.006

  41. 41.

    Chen Y., Guan Y., Zhang Z., Liu H., Wang S., Yu L., Wu X., Wang X. Wnt signaling pathway is involved in the pathogenesis of amyotrophic lateral sclerosis in adult transgenic mice. Neurol. Res. 2012;34:390-399.

    Not in our library10.1179/1743132812y.0000000027

  42. 42.

    Chen Y. PINK1 and Parkin are genetic modifiers for FUS-induced neurodegeneration. Hum. Mol. Genet. 2016;ddw310.

    Not in our library10.1093/hmg/ddw310

  43. 43.

    Ciani L., Salinas P.C. c-Jun N-terminal kinase (JNK) cooperates with Gsk3beta to regulate Dishevelled-mediated microtubule stability. BMC Cell Biol. 2007;8:27.

    Not in our library10.1186/1471-2121-8-27

  44. 44.

    Citterio A. Variants in KIF1A gene in dominant and sporadic forms of hereditary spastic paraparesis. J. Neurol. 2015;262:2684-2690.

    Not in our library10.1007/s00415-015-7899-9

  45. 45.

    Clark J.A., Yeaman E.J., Blizzard C.A., Chuckowree J.A., Dickson T.C. A case for microtubule vulnerability in amyotrophic lateral sclerosis: altered dynamics during disease. Front. Cell. Neurosci. 2016;10:204.

    Not in our library10.3389/fncel.2016.00204

  46. 46.

    Corbo M., Hays A.P. Peripherin and neurofilament protein coexist in spinal spheroids of motor neuron disease. J. Neuropathol. Exp. Neurol. 1992;51:531-537.

    Not in our library10.1097/00005072-199209000-00008

  47. 47.

    Coyne A.N., Siddegowda B.B., Estes P.S., Johannesmeyer J., Kovalik T., Daniel S.G., Pearson A., Bowser R., Zarnescu D.C. Futsch/MAP1B mRNA is a translational target of TDP-43 and is neuroprotective in a Drosophila model of amyotrophic lateral sclerosis. J. Neurosci. 2014;34:15962-15974.

    Not in our library10.1523/jneurosci.2526-14.2014

  48. 48.

    Cozzolino M., Pesaresi M.G., Amori I., Crosio C., Ferri A., Nencini M., Carrì M.T. Oligomerization of mutant SOD1 in mitochondria of motoneuronal cells drives mitochondrial damage and cell toxicity. Antioxid. Redox Signal. 2009;11:1547-1558.

    Not in our library10.1089/ars.2009.2545

  49. 49.

    Curti D., Malaspina A., Facchetti G., Camana C., Mazzini L., Tosca P., Zerbi F., Ceroni M. Amyotrophic lateral sclerosis: oxidative energy metabolism and calcium homeostasis in peripheral blood lymphocytes. Neurology. 1996;47:1060-1064.

    Not in our library10.1212/wnl.47.4.1060

  50. 50.

    De Vos K., Severin F., Van Herreweghe F., Vancompernolle K., Goossens V., Hyman A., Grooten J. Tumor necrosis factor induces hyperphosphorylation of kinesin light chain and inhibits kinesin-mediated transport of mitochondria. J. Cell Biol. 2000;149:1207-1214.

    Not in our library10.1083/jcb.149.6.1207

  51. 51.

    De Vos K.J. Familial amyotrophic lateral sclerosis-linked SOD1 mutants perturb fast axonal transport to reduce axonal mitochondria content. Hum. Mol. Genet. 2007;16:2720-2728.

    Not in our library10.1093/hmg/ddm226

  52. 52.

    De Vos K.J., Grierson A.J., Ackerley S., Miller C.C. Role of axonal transport in neurodegenerative diseases. Annu. Rev. Neurosci. 2008;31:151-173.

    Not in our library10.1146/annurev.neuro.31.061307.090711

  53. 53.

    De Vos K.J., Morotz G.M., Stoica R., Tudor E.L., Lau K.F., Ackerley S., Warley A., Shaw C.E., Miller C.C. VAPB interacts with the mitochondrial protein PTPIP51 to regulate calcium homeostasis. Hum. Mol. Genet. 2012;21:1299-1311.

    Not in our library10.1093/hmg/ddr559

  54. 54.

    Deinhardt K., Salinas S., Verastegui C., Watson R., Worth D., Hanrahan S., Bucci C., Schiavo G. Rab5 and Rab7 control endocytic sorting along the axonal retrograde transport pathway. Neuron. 2006;52:293-305.

    Not in our library10.1016/j.neuron.2006.08.018

  55. 55.

    Delphin C. MAP6-F is a temperature sensor that directly binds to and protects microtubules from cold-induced depolymerization. J. Biol. Chem. 2012;287:35127-35138.

    Not in our library10.1074/jbc.m112.398339

  56. 56.

    Deng W., Garrett C., Dombert B., Soura V., Banks G., Fisher E.M., van der Brug M.P., Hafezparast M. Neurodegenerative mutation in dynein alters its organization and dynein-dynactin and dynein-kinesin interactions. J. Biol. Chem. 2010;285:39922-39934.

    Not in our library10.1074/jbc.m110.178087

  57. 57.

    Devon R.S. Als2-deficient mice exhibit disturbances in endosome trafficking associated with motor behavioral abnormalities. Proc. Natl. Acad. Sci. U. S. A. 2006;103:9595-9600.

    Not in our library10.1073/pnas.0510197103

  58. 58.

    Dewil M., dela Cruz V.F., Van Den Bosch L., Robberecht W. Inhibition of p38 mitogen activated protein kinase activation and mutant SOD1(G93A)-induced motor neuron death. Neurobiol. Dis. 2007;26:332-341.

    Not in our library10.1016/j.nbd.2006.12.023

  59. 59.
  60. 60.

    Dompierre J.P., Godin J.D., Charrin B.C., Cordelieres F.P., King S.J., Humbert S., Saudou F. Histone deacetylase 6 inhibition compensates for the transport deficit in Huntington's disease by increasing tubulin acetylation. J. Neurosci. 2007;27:3571-3583.

    Not in our library10.1523/jneurosci.0037-07.2007

  61. 61.
  62. 62.

    Drum B.M., Yuan C., Li L., Liu Q., Wordeman L., Santana L.F. Oxidative stress decreases microtubule growth and stability in ventricular myocytes. J. Mol. Cell. Cardiol. 2016;93:32-43.

    Not in our library10.1016/j.yjmcc.2016.02.012

  63. 63.

    Ebbing B., Mann K., Starosta A., Jaud J., Schols L., Schule R., Woehlke G. Effect of spastic paraplegia mutations in KIF5A kinesin on transport activity. Hum. Mol. Genet. 2008;17:1245-1252.

    Not in our library10.1093/hmg/ddn014

  64. 64.

    Ebneth A. Overexpression of tau protein inhibits kinesin-dependent trafficking of vesicles, mitochondria, and endoplasmic reticulum: implications for Alzheimer's disease. J. Cell Biol. 1998;143:777-794.

    Not in our library10.1083/jcb.143.3.777

  65. 65.

    El-Kadi A.M., Soura V., Hafezparast M. Defective axonal transport in motor neuron disease. J. Neurosci. Res. 2007;85:2557-2566.

    Not in our library10.1002/jnr.21188

  66. 66.

    El-Kadi A.M. The legs at odd angles (Loa) mutation in dynein ameliorates mitochondrial function in SOD1G93A mouse model for motor neuron disease. J. Biol. Chem. 2010;285:18627-18639.

    Not in our library10.1074/jbc.m110.129320

  67. 67.

    Erlich Y., Edvardson S., Hodges E., Zenvirt S., Thekkat P., Shaag A., Dor T., Hannon G.J., Elpeleg O. Exome sequencing and disease-network analysis of a single family implicate a mutation in KIF1A in hereditary spastic paraparesis. Genome Res. 2011;21:658-664.

    Not in our library10.1101/gr.117143.110

  68. 68.

    Errico A., Ballabio A., Rugarli E.I. Spastin, the protein mutated in autosomal dominant hereditary spastic paraplegia, is involved in microtubule dynamics. Hum. Mol. Genet. 2002;11:153-163.

    Not in our library10.1093/hmg/11.2.153

  69. 69.

    Evans K.J., Gomes E.R., Reisenweber S.M., Gundersen G.G., Lauring B.P. Linking axonal degeneration to microtubule remodeling by Spastin-mediated microtubule severing. J. Cell Biol. 2005;168:599-606.

    Not in our library10.1083/jcb.200409058

  70. 70.

    Fallini C., Bassell G.J., Rossoll W. The ALS disease protein TDP-43 is actively transported in motor neuron axons and regulates axon outgrowth. Hum. Mol. Genet. 2012;21:3703-3718.

    Not in our library10.1093/hmg/dds205

  71. 71.
  72. 72.

    Fanara P., Banerjee J., Hueck R.V., Harper M.R., Awada M., Turner H., Husted K.H., Brandt R., Hellerstein M.K. Stabilization of hyperdynamic microtubules is neuroprotective in amyotrophic lateral sclerosis. J. Biol. Chem. 2007;282:23465-23472.

    Not in our library10.1074/jbc.m703434200

  73. 73.

    Farah C.A., Nguyen M.D., Julien J.P., Leclerc N. Altered levels and distribution of microtubule-associated proteins before disease onset in a mouse model of amyotrophic lateral sclerosis. J. Neurochem. 2003;84:77-86.

    Not in our library10.1046/j.1471-4159.2003.01505.x

  74. 74.

    Farrer M.J. DCTN1 mutations in Perry syndrome. Nat. Genet. 2009;41:163-165.

    Not in our library10.1038/ng.293

  75. 75.

    Feng H.L., Leng Y., Ma C.H., Zhang J., Ren M., Chuang D.M. Combined lithium and valproate treatment delays disease onset, reduces neurological deficits and prolongs survival in an amyotrophic lateral sclerosis mouse model. Neuroscience. 2008;155:567-572.

    Not in our library10.1016/j.neuroscience.2008.06.040

  76. 76.

    Ferraiuolo L. The non-cell-autonomous component of ALS: new in vitro models and future challenges. Biochem. Soc. Trans. 2014;42:1270-1274.

    Not in our library10.1042/bst20140168

  77. 77.

    Ferraiuolo L., Kirby J., Grierson A.J., Sendtner M., Shaw P.J. Molecular pathways of motor neuron injury in amyotrophic lateral sclerosis. Nat. Rev. Neurol. 2011;7:616-630.

    Not in our library10.1038/nrneurol.2011.152

  78. 78.

    Fichera M., Lo Giudice M., Falco M., Sturnio M., Amata S., Calabrese O., Bigoni S., Calzolari E., Neri M. Evidence of kinesin heavy chain (KIF5A) involvement in pure hereditary spastic paraplegia. Neurology. 2004;63:1108-1110.

    Not in our library10.1212/01.wnl.0000138731.60693.d2

  79. 79.

    Fransson S., Ruusala A., Aspenstrom P. The atypical Rho GTPases Miro-1 and Miro-2 have essential roles in mitochondrial trafficking. Biochem. Biophys. Res. Commun. 2006;344:500-510.

    Not in our library10.1016/j.bbrc.2006.03.163

  80. 80.

    Fu M.M., Holzbaur E.L. Integrated regulation of motor-driven organelle transport by scaffolding proteins. Trends Cell Biol. 2014;24:564-574.

    Not in our library10.1016/j.tcb.2014.05.002

  81. 81.

    Fumoto K., Hoogenraad C.C., Kikuchi A. GSK-3beta-regulated interaction of BICD with dynein is involved in microtubule anchorage at centrosome. EMBO J. 2006;25:5670-5682.

    Not in our library10.1038/sj.emboj.7601459

  82. 82.

    Furukawa K., Mattson M.P. Taxol stabilizes [Ca2 +]i and protects hippocampal neurons against excitotoxicity. Brain Res. 1995;689:141-146.

    Not in our library10.1016/0006-8993(95)00537-z

  83. 83.

    Gal J., Chen J., Barnett K.R., Yang L., Brumley E., Zhu H. HDAC6 regulates mutant SOD1 aggregation through two SMIR motifs and tubulin acetylation. J. Biol. Chem. 2013;288:15035-15045.

    Not in our library10.1074/jbc.m112.431957

  84. 84.

    Gallagher M.D. TMEM106B is a genetic modifier of frontotemporal lobar degeneration with C9orf72 hexanucleotide repeat expansions. Acta Neuropathol. 2014;127:407-418.

    Not in our library10.1007/s00401-013-1239-x

  85. 85.

    Gao F.J., Hebbar S., Gao X.A., Alexander M., Pandey J.P., Walla M.D., Cotham W.E., King S.J., Smith D.S. GSK-3β phosphorylation of dynein reduces Ndel1 binding to intermediate chains and alters dynein motility. Traffic. 2015;16:941-961.

    Not in our library10.1111/tra.12304

  86. 86.

    Garrett C.A., Barri M., Kuta A., Soura V., Deng W., Fisher E.M., Schiavo G., Hafezparast M. DYNC1H1 mutation alters transport kinetics and ERK1/2-cFos signalling in a mouse model of distal spinal muscular atrophy. Brain. 2014;137:1883-1893.

    Not in our library10.1093/brain/awu097

  87. 87.
  88. 88.

    Gentil B.J., Tibshirani M., Durham H.D. Neurofilament dynamics and involvement in neurological disorders. Cell Tissue Res. 2015;360:609-620.

    Not in our library10.1007/s00441-014-2082-7

  89. 89.

    Ghazi-Noori S. Progressive neuronal inclusion formation and axonal degeneration in CHMP2B mutant transgenic mice. Brain. 2012;135:819-832.

    Not in our library10.1093/brain/aws006

  90. 90.

    Gibbs K.L., Greensmith L., Schiavo G. Regulation of axonal transport by protein kinases. Trends Biochem. Sci. 2015;40:597-610.

    Not in our library10.1016/j.tibs.2015.08.003

  91. 91.

    Gill A., Kidd J., Vieira F., Thompson K., Perrin S. No benefit from chronic lithium dosing in a sibling-matched, gender balanced, investigator-blinded trial using a standard mouse model of familial ALS. PLoS One. 2009;4.

    Not in our library10.1371/journal.pone.0006489

  92. 92.

    Gilley J. Age-dependent axonal transport and locomotor changes and tau hypophosphorylation in a “P301L” tau knockin mouse. Neurobiol. Aging. 2012;33(621).

    Not in our library10.1016/j.neurobiolaging.2011.02.014

  93. 93.

    Glater E.E., Megeath L.J., Stowers R.S., Schwarz T.L. Axonal transport of mitochondria requires milton to recruit kinesin heavy chain and is light chain independent. J. Cell Biol. 2006;173:545-557.

    Not in our library10.1083/jcb.200601067

  94. 94.
  95. 95.
  96. 96.
  97. 97.

    Grosskreutz J., Van Den Bosch L., Keller B.U. Calcium dysregulation in amyotrophic lateral sclerosis. Cell Calcium. 2010;47:165-174.

    Not in our library10.1016/j.ceca.2009.12.002

  98. 98.

    Grundke-Iqbal I., Iqbal K., Quinlan M., Tung Y.-C., Zaidi M., Wisniewski H. Microtubule-associated protein tau. A component of Alzheimer paired helical filaments. J. Biol. Chem. 1986;61:6084-6089.

    Not in our library

  99. 99.

    Guidato S., Tsai L.H., Woodgett J., Miller C.C. Differential cellular phosphorylation of neurofilament heavy side-arms by glycogen synthase kinase-3 and cyclin-dependent kinase-5. J. Neurochem. 1996;66:1698-1706.

    Not in our library10.1046/j.1471-4159.1996.66041698.x

  100. 100.

    Gustavsson E.K. DCTN1 p.K56R in progressive supranuclear palsy. Parkinsonism Relat. Disord. 2016;28:56-61.

    Not in our library10.1016/j.parkreldis.2016.04.025

  101. 101.

    Hadano S. Mice deficient in the Rab5 guanine nucleotide exchange factor ALS2/alsin exhibit age-dependent neurological deficits and altered endosome trafficking. Hum. Mol. Genet. 2006;15:233-250.

    Not in our library10.1093/hmg/ddi440

  102. 102.

    Hafezparast M. Mutations in dynein link motor neuron degeneration to defects in retrograde transport. Science. 2003;300:808-812.

    Not in our library10.1126/science.1083129

  103. 103.

    Halievski K., Kemp M.Q., Breedlove S.M., Miller K.E., Jordan C.L. Non-Cell-Autonomous Regulation of Retrograde Motoneuronal Axonal Transport in an SBMA Mouse Model. eNeuro 3, ENEURO.0062-16.2016. 2016.

    Not in our library10.1523/eneuro.0062-16.2016

  104. 104.

    Hammond J.W., Huang C.F., Kaech S., Jacobson C., Banker G., Verhey K.J. Posttranslational modifications of tubulin and the polarized transport of kinesin-1 in neurons. Mol. Biol. Cell. 2010;21:572-583.

    Not in our library10.1091/mbc.e09-01-0044

  105. 105.

    Hanger D.P., Noble W. Functional implications of glycogen synthase kinase-3-mediated tau phosphorylation. Int. J. Alzheimers Dis. 2011;2011:352805.

    Not in our library10.4061/2011/352805

  106. 106.

    Hazan J. Spastin, a new AAA protein, is altered in the most frequent form of autosomal dominant spastic paraplegia. Nat. Genet. 1999;23:296-303.

    Not in our library10.1038/15472

  107. 107.

    Hinckelmann M.V., Virlogeux A., Niehage C., Poujol C., Choquet D., Hoflack B., Zala D., Saudou F. Self-propelling vesicles define glycolysis as the minimal energy machinery for neuronal transport. Nat. Commun. 2016;7:13233.

    Not in our library10.1038/ncomms13233

  108. 108.

    Hirano A., Donnenfeld H., Sasaki S., Nakano I. Fine structural observations of neurofilamentous changes in amyotrophic lateral sclerosis. J. Neuropathol. Exp. Neurol. 1984;43:461-470.

    Not in our library10.1097/00005072-198409000-00001

  109. 109.

    Hirano A., Nakano I., Kurland L.T., Mulder D.W., Holley P.W., Saccomanno G. Fine structural study of neurofibrillary changes in a family with amyotrophic lateral sclerosis. J. Neuropathol. Exp. Neurol. 1984;43:471-480.

    Not in our library10.1097/00005072-198409000-00002

  110. 110.

    Hirokawa N., Niwa S., Tanaka Y. Molecular motors in neurons: transport mechanisms and roles in brain function, development, and disease. Neuron. 2010;68:610-638.

    Not in our library10.1016/j.neuron.2010.09.039

  111. 111.

    Holasek S.S., Wengenack T.M., Kandimalla K.K., Montano C., Gregor D.M., Curran G.L., Poduslo J.F. Activation of the stress-activated MAP kinase, p38, but not JNK in cortical motor neurons during early presymptomatic stages of amyotrophic lateral sclerosis in transgenic mice. Brain Res. 2005;1045:185-198.

    Not in our library10.1016/j.brainres.2005.03.037

  112. 112.

    Horiuchi D., Collins C.A., Bhat P., Barkus R.V., Diantonio A., Saxton W.M. Control of a kinesin-cargo linkage mechanism by JNK pathway kinases. Curr. Biol. 2007;17:1313-1317.

    Not in our library10.1016/j.cub.2007.06.062

  113. 113.

    Hu J.H., Chernoff K., Pelech S., Krieger C. Protein kinase and protein phosphatase expression in the central nervous system of G93A mSOD over-expressing mice. J. Neurochem. 2003;85:422-431.

    Not in our library10.1046/j.1471-4159.2003.01669.x

  114. 114.

    Hu J.H., Zhang H., Wagey R., Krieger C., Pelech S.L. Protein kinase and protein phosphatase expression in amyotrophic lateral sclerosis spinal cord. J. Neurochem. 2003;85:432-442.

    Not in our library10.1046/j.1471-4159.2003.01670.x

  115. 115.

    Huang S.H., Duan S., Sun T., Wang J., Zhao L., Geng Z., Yan J., Sun H.J., Chen Z.Y. JIP3 mediates TrkB axonal anterograde transport and enhances BDNF signaling by directly bridging TrkB with kinesin-1. J. Neurosci. 2011;31:10602-10614.

    Not in our library10.1523/jneurosci.0436-11.2011

  116. 116.

    Hubbert C., Guardiola A., Shao R., Kawaguchi Y., Ito A., Nixon A., Yoshida M., Wang X.-F., Yao T.P. HDAC6 is a microtubule-associated deacetylase. Nature. 2002;417:455-458.

    Not in our library10.1038/417455a

  117. 117.

    Igoudjil A., Magrane J., Fischer L.R., Kim H.J., Hervias I., Dumont M., Cortez C., Glass J.D., Starkov A.A., Manfredi G. In vivo pathogenic role of mutant SOD1 localized in the mitochondrial intermembrane space. J. Neurosci. 2011;31:15826-15837.

    Not in our library10.1523/jneurosci.1965-11.2011

  118. 118.

    Ilieva H.S., Yamanaka K., Malkmus S., Kakinohana O., Yaksh T., Marsala M., Cleveland D.W. Mutant dynein (Loa) triggers proprioceptive axon loss that extends survival only in the SOD1 ALS model with highest motor neuron death. Proc. Natl. Acad. Sci. U. S. A. 2008;105:12599-12604.

    Not in our library10.1073/pnas.0805422105

  119. 119.

    Iqbal K., Liu F., Gong C.X. Tau and neurodegenerative disease: the story so far. Nat. Rev. Neurol. 2016;12:15-27.

    Not in our library10.1038/nrneurol.2015.225

  120. 120.

    Ishiguro A., Kimura N., Watanabe Y., Watanabe S., Ishihama A. TDP-43 binds and transports G-quadruplex-containing mRNAs into neurites for local translation. Genes Cells. 2016;21:466-481.

    Not in our library10.1111/gtc.12352

  121. 121.

    Israelson A., Arbel N., Da Cruz S., Ilieva H., Yamanaka K., Shoshan-Barmatz V., Cleveland D.W. Misfolded mutant SOD1 directly inhibits VDAC1 conductance in a mouse model of inherited ALS. Neuron. 2010;67:575-587.

    Not in our library10.1016/j.neuron.2010.07.019

  122. 122.

    Jaarsma D., Holstege J.C., Troost D., Davis M., Kennis J., Haasdijk E.D., de Jong V.J. Induction of c-Jun immunoreactivity in spinal cord and brainstem neurons in a transgenic mouse model for amyotrophic lateral sclerosis. Neurosci. Lett. 1996;219:179-182.

    Not in our library10.1016/s0304-3940(96)13202-x

  123. 123.

    Jeon S.H., Kim Y.S., Bae C.D., Park J.B. Activation of JNK and p38 in rat hippocampus after kainic acid induced seizure. Exp. Mol. Med. 2000;32:227-230.

    Not in our library10.1038/emm.2000.37

  124. 124.

    Jimenez-Mateos E.M., Gonzalez-Billault C., Dawson H.N., Vitek M.P., Avila J. Role of MAP1B in axonal retrograde transport of mitochondria. Biochem. J. 2006;397:53-59.

    Not in our library10.1042/bj20060205

  125. 125.

    Job D., Fischer E.H., Margolis R.L. Rapid disassembly of cold-stable microtubules by calmodulin. Proc. Natl. Acad. Sci. U. S. A. 1981;78:4679-4682.

    Not in our library10.1073/pnas.78.8.4679

  126. 126.

    John G.B., Shang Y., Li L., Renken C., Mannella C.A., Selker J.M., Rangell L., Bennett M.J., Zha J. The mitochondrial inner membrane protein mitofilin controls cristae morphology. Mol. Biol. Cell. 2005;16:1543-1554.

    Not in our library10.1091/mbc.e04-08-0697

  127. 127.

    Jung C., Lee S., Ortiz D., Zhu Q., Julien J.P., Shea T.B. The high and middle molecular weight neurofilament subunits regulate the association of neurofilaments with kinesin: inhibition by phosphorylation of the high molecular weight subunit. Brain Res. Mol. Brain Res. 2005;141:151-155.

    Not in our library10.1016/j.molbrainres.2005.08.009

  128. 128.

    Kabuta T., Kinugawa A., Tsuchiya Y., Kabuta C., Setsuie R., Tateno M., Araki T., Wada K. Familial amyotrophic lateral sclerosis-linked mutant SOD1 aberrantly interacts with tubulin. Biochem. Biophys. Res. Commun. 2009;387:121-126.

    Not in our library10.1016/j.bbrc.2009.06.138

  129. 129.

    Kardon J.R., Vale R.D. Regulators of the dynein motor. Nat. Rev. Mol. Cell Biol. 2009;10:854-865.

    Not in our library10.1038/nrm2804

  130. 130.

    Kasher P.R. Direct evidence for axonal transport defects in a novel mouse model of mutant spastin-induced hereditary spastic paraplegia (HSP) and human HSP patients. J. Neurochem. 2009;110:34-44.

    Not in our library10.1111/j.1471-4159.2009.06104.x

  131. 131.

    Katsuno M. Reversible disruption of dynactin 1-mediated retrograde axonal transport in polyglutamine-induced motor neuron degeneration. J. Neurosci. 2006;26:12106-12117.

    Not in our library10.1523/jneurosci.3032-06.2006

  132. 132.

    Kawaguchi Y., Kovacs J.J., McLaurin A., Vance J.M., Ito A., Yao T.P. The deacetylase HDAC6 regulates aggresome formation and cell viability in response to misfolded protein stress. Cell. 2003;115:727-738.

    Not in our library10.1016/s0092-8674(03)00939-5

  133. 133.

    Kawasaki H., Morooka T., Shimohama S., Kimura J., Hirano T., Gotoh Y., Nishida E. Activation and involvement of p38 mitogen-activated protein kinase in glutamate-induced apoptosis in rat cerebellar granule cells. J. Biol. Chem. 1997;272:18518-18521.

    Not in our library10.1074/jbc.272.30.18518

  134. 134.

    Kieran D., Hafezparast M., Bohnert S., Dick J.R., Martin J., Schiavo G., Fisher E.M., Greensmith L. A mutation in dynein rescues axonal transport defects and extends the life span of ALS mice. J. Cell Biol. 2005;169:561-567.

    Not in our library10.1083/jcb.200501085

  135. 135.

    Kiernan M.C., Vucic S., Cheah B.C., Turner M.R., Eisen A., Hardiman O., Burrell J.R., Zoing M.C. Amyotrophic lateral sclerosis. Lancet. 2011;377:942-955.

    Not in our library10.1016/s0140-6736(10)61156-7

  136. 136.

    Kim S.H., Shanware N.P., Bowler M.J., Tibbetts R.S. Amyotrophic lateral sclerosis-associated proteins TDP-43 and FUS/TLS function in a common biochemical complex to co-regulate HDAC6 mRNA. J. Biol. Chem. 2010;285:34097-34105.

    Not in our library10.1074/jbc.m110.154831

  137. 137.

    Kim J.Y., Jang A., Reddy R., Hee Yoon W., Jankowsky J.L. Neuronal overexpression of human VAPB slows motor impairment and neuromuscular denervation in a mouse model of ALS. Hum. Mol. Genet. 2016;ddw294.

    Not in our library10.1093/hmg/ddw294

  138. 138.

    King S.M. Dyneins: Structure, Biology and Disease. 2012.

    Not in our library

  139. 139.

    Kleele T. An assay to image neuronal microtubule dynamics in mice. Nat. Commun. 2014;5:4827.

    Not in our library10.1038/ncomms5827

  140. 140.

    Klinman E., Holzbaur E.L. Stress-induced CDK5 activation disrupts axonal transport via Lis1/Ndel1/dynein. Cell Rep. 2015;12:462-473.

    Not in our library10.1016/j.celrep.2015.06.032

  141. 141.

    Koh S.H., Lee Y.B., Kim K.S., Kim H.J., Kim M., Lee Y.J., Kim J., Lee K.W., Kim S.H. Role of GSK-3beta activity in motor neuronal cell death induced by G93A or A4V mutant hSOD1 gene. Eur. J. Neurosci. 2005;22:301-309.

    Not in our library10.1111/j.1460-9568.2005.04191.x

  142. 142.

    Koh S.H., Kim Y., Kim H.Y., Hwang S., Lee C.H., Kim S.H. Inhibition of glycogen synthase kinase-3 suppresses the onset of symptoms and disease progression of G93A-SOD1 mouse model of ALS. Exp. Neurol. 2007;205:336-346.

    Not in our library10.1016/j.expneurol.2007.03.004

  143. 143.

    Konishi Y., Setou M. Tubulin tyrosination navigates the kinesin-1 motor domain to axons. Nat. Neurosci. 2009;12:559-567.

    Not in our library10.1038/nn.2314

  144. 144.

    Kratzer E., Tian Y., Sarich N., Wu T., Meliton A., Leff A., Birukova A.A. Oxidative stress contributes to lung injury and barrier dysfunction via microtubule destabilization. Am. J. Respir. Cell Mol. Biol. 2012;47:688-697.

    Not in our library10.1165/rcmb.2012-0161oc

  145. 145.

    Kusakawa G., Saito T., Onuki R., Ishiguro K., Kishimoto T., Hisanaga S. Calpain-dependent proteolytic cleavage of the p35 cyclin-dependent kinase 5 activator to p25. J. Biol. Chem. 2000;275:17166-17172.

    Not in our library10.1074/jbc.m907757199

  146. 146.

    Lai C. Amyotrophic lateral sclerosis 2-deficiency leads to neuronal degeneration in amyotrophic lateral sclerosis through altered AMPA receptor trafficking. J. Neurosci. 2006;26:11798-11806.

    Not in our library10.1523/jneurosci.2084-06.2006

  147. 147.

    Lai C., Lin X., Chandran J., Shim H., Yang W.J., Cai H. The G59S mutation in p150(glued) causes dysfunction of dynactin in mice. J. Neurosci. 2007;27:13982-13990.

    Not in our library10.1523/jneurosci.4226-07.2007

  148. 148.

    Lai C., Xie C., Shim H., Chandran J., Howell B.W., Cai H. Regulation of endosomal motility and degradation by amyotrophic lateral sclerosis 2/alsin. Mol. Brain. 2009;2:23.

    Not in our library10.1186/1756-6606-2-23

  149. 149.

    Laird F.M., Farah M.H., Ackerley S., Hoke A., Maragakis N., Rothstein J.D., Griffin J., Price D.L., Martin L.J., Wong P.C. Motor neuron disease occurring in a mutant dynactin mouse model is characterized by defects in vesicular trafficking. J. Neurosci. 2008;28:1997-2005.

    Not in our library10.1523/jneurosci.4231-07.2008

  150. 150.

    LaMonte B.H., Wallace K.E., Holloway B.A., Shelly S.S., Ascano J., Tokito M., Van Winkle T., Howland D.S., Holzbaur E.L. Disruption of dynein/dynactin inhibits axonal transport in motor neurons causing late-onset progressive degeneration. Neuron. 2002;34:715-727.

    Not in our library10.1016/s0896-6273(02)00696-7

  151. 151.

    Lautenschlager J., Prell T., Ruhmer J., Weidemann L., Witte O.W., Grosskreutz J. Overexpression of human mutated G93A SOD1 changes dynamics of the ER mitochondria calcium cycle specifically in mouse embryonic motor neurons. Exp. Neurol. 2013;247:91-100.

    Not in our library10.1016/j.expneurol.2013.03.027

  152. 152.

    Lee M.S., Kwon Y.T., Li M., Peng J., Friedlander R.M., Tsai L.H. Neurotoxicity induces cleavage of p35 to p25 by calpain. Nature. 2000;405:360-364.

    Not in our library10.1038/35012636

  153. 153.

    Lee S., Pant H.C., Shea T.B. Divergent and convergent roles for kinases and phosphatases in neurofilament dynamics. J. Cell Sci. 2014;127:4064-4077.

    Not in our library10.1242/jcs.153346

  154. 154.

    Lee J.R. De novo mutations in the motor domain of KIF1A cause cognitive impairment, spastic paraparesis, axonal neuropathy, and cerebellar atrophy. Hum. Mutat. 2015;36:69-78.

    Not in our library10.1002/humu.22709

  155. 155.

    Lee J.Y., Kawaguchi Y., Li M., Kapur M., Choi S.J., Kim H.J., Park S.Y., Zhu H., Yao T.P. Uncoupling of protein aggregation and neurodegeneration in a mouse amyotrophic lateral sclerosis model. Neurodegener. Dis. 2015;15:339-349.

    Not in our library10.1159/000437208

  156. 156.

    Lee S. Activation of HIPK2 promotes ER stress-mediated neurodegeneration in amyotrophic lateral sclerosis. Neuron. 2016;91:41-55.

    Not in our library10.1016/j.neuron.2016.05.021

  157. 157.

    Lefèvre J., Savarin P., Gans P., Hamon L., Clément M.J., David M.O., Bosc C., Andrieux A., Curmi P.A. Structural basis for the association of MAP6 protein with microtubules and its regulation by calmodulin. J. Biol. Chem. 2013;288:24910-24922.

    Not in our library10.1074/jbc.m113.457267

  158. 158.

    Letournel F., Bocquet A., Dubas F., Barthelaix A., Eyer J. Stable tubule only polypeptides (STOP) proteins co-aggregate with spheroid neurofilaments in amyotrophic lateral sclerosis. J. Neuropathol. Exp. Neurol. 2003;62:1211-1219.

    Not in our library10.1093/jnen/62.12.1211

  159. 159.

    Levy J.R. A motor neuron disease-associated mutation in p150Glued perturbs dynactin function and induces protein aggregation. J. Cell Biol. 2006;172:733-745.

    Not in our library10.1083/jcb.200511068

  160. 160.

    Li Q. ALS-linked mutant superoxide dismutase 1 (SOD1) alters mitochondrial protein composition and decreases protein import. Proc. Natl. Acad. Sci. U. S. A. 2010;107:21146-21151.

    Not in our library10.1073/pnas.1014862107

  161. 161.

    Ligon L.A., LaMonte B.H., Wallace K.E., Weber N., Kalb R.G., Holzbaur E.L. Mutant superoxide dismutase disrupts dynein in motor neurons. Neuroreport. 2005;16:533-536.

    Not in our library10.1097/00001756-200504250-00002

  162. 162.

    Lipka J., Kuijpers M., Jaworski J., Hoogenraad C.C. Mutations in dynein and its regulators cause malformations of cortical development and neurodegenerative diseases. Biochem. Soc. Trans. 2013;41:1605-1612.

    Not in our library10.1042/bst20130188

  163. 163.

    Liu J. Toxicity of familial ALS-linked SOD1 mutants from selective recruitment to spinal mitochondria. Neuron. 2004;43:5-17.

    Not in our library10.1016/j.neuron.2004.06.016

  164. 164.
  165. 165.

    López E., Casasnovas C., Giménez J., Santamaría R., Terrazas J.M., Volpini V. Identification of two novel KIF5A mutations in hereditary spastic paraplegia associated with mild peripheral neuropathy. J. Neurol. Sci. 2015;358:422-427.

    Not in our library10.1016/j.jns.2015.08.1529

  166. 166.
  167. 167.

    MacAskill A.F., Brickley K., Stephenson F.A., Kittler J.T. GTPase dependent recruitment of Grif-1 by Miro1 regulates mitochondrial trafficking in hippocampal neurons. Mol. Cell. Neurosci. 2009;40:301-312.

    Not in our library10.1016/j.mcn.2008.10.016

  168. 168.
  169. 169.

    Magnani E., Fan J., Gasparini L., Golding M., Williams M., Schiavo G., Goedert M., Amos L.A., Spillantini M.G. Interaction of tau protein with the dynactin complex. EMBO J. 2007;26:4546-4554.

    Not in our library10.1038/sj.emboj.7601878

  170. 170.

    Magrané J., Hervias I., Henning M.S., Damiano M., Kawamata H., Manfredi G. Mutant SOD1 in neuronal mitochondria causes toxicity and mitochondrial dynamics abnormalities. Hum. Mol. Genet. 2009;18:4552-4564.

    Not in our library10.1093/hmg/ddp421

  171. 171.

    Magrané J., Sahawneh M.A., Przedborski S., Estevez A.G., Manfredi G. Mitochondrial dynamics and bioenergetic dysfunction is associated with synaptic alterations in mutant SOD1 motor neurons. J. Neurosci. 2012;32:229-242.

    Not in our library10.1523/jneurosci.1233-11.2012

  172. 172.

    Magrané J., Cortez C., Gan W.B., Manfredi G. Abnormal mitochondrial transport and morphology are common pathological denominators in SOD1 and TDP43 ALS mouse models. Hum. Mol. Genet. 2014;23:1413-1424.

    Not in our library10.1093/hmg/ddt528

  173. 173.

    Manser C., Guillot F., Vagnoni A., Davies J., Lau K.F., McLoughlin D.M., De Vos K.J., Miller C.C. Lemur tyrosine kinase-2 signalling regulates kinesin-1 light chain-2 phosphorylation and binding of Smad2 cargo. Oncogene. 2012;31:2773-2782.

    Not in our library10.1038/onc.2011.437

  174. 174.

    Marinkovic P., Reuter M.S., Brill M.S., Godinho L., Kerschensteiner M., Misgeld T. Axonal transport deficits and degeneration can evolve independently in mouse models of amyotrophic lateral sclerosis. Proc. Natl. Acad. Sci. U. S. A. 2012;109:4296-4301.

    Not in our library10.1073/pnas.1200658109

  175. 175.

    Martin N., Jaubert J., Gounon P., Salido E., Haase G., Szatanik M., Guenet J.L. A missense mutation in Tbce causes progressive motor neuronopathy in mice. Nat. Genet. 2002;32:443-447.

    Not in our library10.1038/ng1016

  176. 176.

    Matamoros A.J., Baas P.W. Microtubules in health and degenerative disease of the nervous system. Brain Res. Bull. 2016;126:217-225.

    Not in our library10.1016/j.brainresbull.2016.06.016

  177. 177.

    Mattiazzi M., D'Aurelio M., Gajewski C.D., Martushova K., Kiaei M., Beal M.F., Manfredi G. Mutated human SOD1 causes dysfunction of oxidative phosphorylation in mitochondria of transgenic mice. J. Biol. Chem. 2002;277:29626-29633.

    Not in our library10.1074/jbc.m203065200

  178. 178.
  179. 179.

    McDermott C.J., Grierson A.J., Wood J.D., Bingley M., Wharton S.B., Bushby K.M., Shaw P.J. Hereditary spastic paraparesis: disrupted intracellular transport associated with spastin mutation. Ann. Neurol. 2003;54:748-759.

    Not in our library10.1002/ana.10757

  180. 180.
  181. 181.

    Milde S., Adalbert R., Elaman M.H., Coleman M.P. Axonal transport declines with age in two distinct phases separated by a period of relative stability. Neurobiol. Aging. 2015;36:971-981.

    Not in our library10.1016/j.neurobiolaging.2014.09.018

  182. 182.

    Millecamps S., Julien J.P. Axonal transport deficits and neurodegenerative diseases. Nat. Rev. Neurosci. 2013;14:161-176.

    Not in our library10.1038/nrn3380

  183. 183.

    Mitne-Neto M. Downregulation of VAPB expression in motor neurons derived from induced pluripotent stem cells of ALS8 patients. Hum. Mol. Genet. 2011;20:3642-3652.

    Not in our library10.1093/hmg/ddr284

  184. 184.

    Morfini G., Szebenyi G., Elluru R., Ratner N., Brady S.T. Glycogen synthase kinase 3 phosphorylates kinesin light chains and negatively regulates kinesin-based motility. EMBO J. 2002;21:281-293.

    Not in our library10.1093/emboj/21.3.281

  185. 185.

    Morfini G., Szebenyi G., Brown H., Pant H.C., Pigino G., DeBoer S., Beffert U., Brady S.T. A novel CDK5-dependent pathway for regulating GSK3 activity and kinesin-driven motility in neurons. EMBO J. 2004;23:2235-2245.

    Not in our library10.1038/sj.emboj.7600237

  186. 186.

    Morfini G., Pigino G., Szebenyi G., You Y., Pollema S., Brady S.T. JNK mediates pathogenic effects of polyglutamine-expanded androgen receptor on fast axonal transport. Nat. Neurosci. 2006;9:907-916.

    Not in our library10.1038/nn1717

  187. 187.

    Morfini G.A. Pathogenic huntingtin inhibits fast axonal transport by activating JNK3 and phosphorylating kinesin. Nat. Neurosci. 2009;12:864-871.

    Not in our library10.1038/nn.2346

  188. 188.

    Morfini G.A. Inhibition of fast axonal transport by pathogenic SOD1 involves activation of p38 MAP kinase. PLoS One. 2013;8.

    Not in our library10.1371/journal.pone.0065235

  189. 189.

    Morlino G. Miro-1 links mitochondria and microtubule Dynein motors to control lymphocyte migration and polarity. Mol. Cell. Biol. 2014;34:1412-1426.

    Not in our library10.1128/mcb.01177-13

  190. 190.

    Morotz G.M., De Vos K.J., Vagnoni A., Ackerley S., Shaw C.E., Miller C.C. Amyotrophic lateral sclerosis-associated mutant VAPBP56S perturbs calcium homeostasis to disrupt axonal transport of mitochondria. Hum. Mol. Genet. 2012;21:1979-1988.

    Not in our library10.1093/hmg/dds011

  191. 191.

    Muglia M. A novel KIF5A mutation in an Italian family marked by spastic paraparesis and congenital deafness. J. Neurol. Sci. 2014;343:218-220.

    Not in our library10.1016/j.jns.2014.05.063

  192. 192.

    Munch C. Point mutations of the p150 subunit of dynactin (DCTN1) gene in ALS. Neurology. 2004;63:724-726.

    Not in our library10.1212/01.wnl.0000134608.83927.b1

  193. 193.

    Munch C. Heterozygous R1101K mutation of the DCTN1 gene in a family with ALS and FTD. Ann. Neurol. 2005;58:777-780.

    Not in our library10.1002/ana.20631

  194. 194.

    Nagy M., Fenton W.A., Li D., Furtak K., Horwich A.L. Extended survival of misfolded G85R SOD1-linked ALS mice by transgenic expression of chaperone Hsp110. Proc. Natl. Acad. Sci. U. S. A. 2016;113:5424-5428.

    Not in our library10.1073/pnas.1604885113

  195. 195.

    Nangaku M., Sato-Yoshitake R., Okada Y., Noda Y., Takemura R., Yamazaki H., Hirokawa N. KIF1B, a novel microtubule plus end-directed monomeric motor protein for transport of mitochondria. Cell. 1994;79:1209-1220.

    Not in our library10.1016/0092-8674(94)90012-4

  196. 196.

    Nguyen M.D., Larivière R.C., Julien J.-P. Deregulation of Cdk5 in a mouse model of ALS. Neuron. 2001;30:135-148.

    Not in our library10.1016/s0896-6273(01)00268-9

  197. 197.

    Niwa S., Tanaka Y., Hirokawa N. KIF1Bbeta- and KIF1A-mediated axonal transport of presynaptic regulator Rab3 occurs in a GTP-dependent manner through DENN/MADD. Nat. Cell Biol. 2008;10:1269-1279.

    Not in our library10.1038/ncb1785

  198. 198.

    Norkett R., Modi S., Birsa N., Atkin T.A., Ivankovic D., Pathania M., Trossbach S.V., Korth C., Hirst W.D., Kittler J.T. DISC1-dependent regulation of mitochondrial dynamics controls the morphogenesis of complex neuronal dendrites. J. Biol. Chem. 2016;291:613-629.

    Not in our library10.1074/jbc.m115.699447

  199. 199.

    North B.J., Marshall B.L., Borra M.T., Denu J.M., Verdin E. The human Sir2 Ortholog, SIRT2, is an NAD +−dependent tubulin deacetylase. Mol. Cell. 2003;11:437-444.

    Not in our library10.1016/s1097-2765(03)00038-8

  200. 200.

    Ogawa F., Malavasi E.L., Crummie D.K., Eykelenboom J.E., Soares D.C., Mackie S., Porteous D.J., Millar J.K. DISC1 complexes with TRAK1 and Miro1 to modulate anterograde axonal mitochondrial trafficking. Hum. Mol. Genet. 2014;23:906-919.

    Not in our library10.1093/hmg/ddt485

  201. 201.

    Ogawa F., Murphy L.C., Malavasi E.L., O'Sullivan S.T., Torrance H.S., Porteous D.J., Millar J.K. NDE1 and GSK3β associate with TRAK1 and regulate axonal mitochondrial motility: identification of cyclic AMP as a novel modulator of axonal mitochondrial trafficking. ACS Chem. Neurosci. 2016;7:553-564.

    Not in our library10.1021/acschemneuro.5b00255

  202. 202.

    Okada Y., Yamazaki H., Sekine-Aizawa Y., Hirokawa N. The neuron-specific kinesin superfamily protein KIF1A is a unique monomeric motor for anterograde axonal transport of synaptic vesicle precursors. Cell. 1995;81:769-780.

    Not in our library10.1016/0092-8674(95)90538-3

  203. 203.

    Ori-McKenney K.M., Xu J., Gross S.P., Vallee R.B. A dynein tail mutation impairs motor processivity. Nat. Cell Biol. 2010;12:1228-1234.

    Not in our library10.1038/ncb2127

  204. 204.
  205. 205.

    Panda D., Jordan M.A., Chu K.C., Wilson L. Differential effects of vinblastine on polymerization and dynamics at opposite microtubule ends. J. Biol. Chem. 1996;271:29807-29812.

    Not in our library10.1074/jbc.271.47.29807

  206. 206.

    Parakh S., Atkin J.D. Protein folding alterations in amyotrophic lateral sclerosis. Brain Res. 2016;1648:633-649.

    Not in our library10.1016/j.brainres.2016.04.010

  207. 207.

    Park Y.U., Jeong J., Lee H., Mun J.Y., Kim J.H., Lee J.S., Nguyen M.D., Han S.S., Suh P.G., Park S.K. Disrupted-in-schizophrenia 1 (DISC1) plays essential roles in mitochondria in collaboration with Mitofilin. Proc. Natl. Acad. Sci. U. S. A. 2010;107:17785-17790.

    Not in our library10.1073/pnas.1004361107

  208. 208.

    Park C. Disrupted-in-schizophrenia 1 (DISC1) and Syntaphilin collaborate to modulate axonal mitochondrial anchoring. Mol. Brain. 2016;9:69.

    Not in our library10.1186/s13041-016-0250-2

  209. 209.

    Pasinelli P., Belford M.E., Lennon N., Bacskai B.J., Hyman B.T., Trotti D., Brown R.H.J. Amyotrophic lateral sclerosis-associated SOD1 mutant proteins bind and aggregate with Bcl-2 in spinal cord mitochondria. Neuron. 2004;43:19-30.

    Not in our library10.1016/j.neuron.2004.06.021

  210. 210.

    Patrick G.N., Zukerberg L., Nikolic M., de la Monte S., Dikkes P., Tsai L.H. Conversion of p35 to p25 deregulates Cdk5 activity and promotes neurodegeneration. Nature. 1999;402:615-622.

    Not in our library10.1038/45159

  211. 211.

    Perez-Branguli F. Dysfunction of spatacsin leads to axonal pathology in SPG11-linked hereditary spastic paraplegia. Hum. Mol. Genet. 2014;23:4859-4874.

    Not in our library10.1093/hmg/ddu200

  212. 212.

    Perlson E., Jeong G.B., Ross J.L., Dixit R., Wallace K.E., Kalb R.G., Holzbaur E.L. A switch in retrograde signaling from survival to stress in rapid-onset neurodegeneration. J. Neurosci. 2009;29:9903-9917.

    Not in our library10.1523/jneurosci.0813-09.2009

  213. 213.

    Perrot R., Julien J.P. Real-time imaging reveals defects of fast axonal transport induced by disorganization of intermediate filaments. FASEB J. 2009;23:3213-3225.

    Not in our library10.1096/fj.09-129585

  214. 214.

    Pickles S., Destroismaisons L., Peyrard S.L., Cadot S., Rouleau G.A., Brown R.H., Julien J.P., Arbour N., Vande Velde C. Mitochondrial damage revealed by immunoselection for ALS-linked misfolded SOD1. Hum. Mol. Genet. 2013;22:3947-3959.

    Not in our library10.1093/hmg/ddt249

  215. 215.

    Pickles S., Semmler S., Broom H.R., Destroismaisons L., Legroux L., Arbour N., Meiering E., Cashman N.R., Vande Velde C. ALS-linked misfolded SOD1 species have divergent impacts on mitochondria. Acta Neuropathol. Commun. 2016;4:43.

    Not in our library10.1186/s40478-016-0313-8

  216. 216.

    Piñero-Martos E., Ortega-Vila B., Pol-Fuster J., Cisneros-Barroso E., Ruiz-Guerra L., Medina-Dols A., Heine-Suñer D., Lladó J., Olmos G., Vives-Bauzà C. Disrupted in schizophrenia 1 (DISC1) is a constituent of the mammalian mitochondrial contact site and cristae organizing system (MICOS) complex, and is essential for oxidative phosphorylation. Hum. Mol. Genet. 2016;ddw250.

    Not in our library10.1093/hmg/ddw250

  217. 217.

    Pizzasegola C., Caron I., Daleno C., Ronchi A., Minoia C., Carrì M.T., Bendotti C. Treatment with lithium carbonate does not improve disease progression in two different strains of SOD1 mutant mice. Amyotroph. Lateral Scler. 2009;10:221-228.

    Not in our library10.1080/17482960902803440

  218. 218.

    Puls I. Mutant dynactin in motor neuron disease. Nat. Genet. 2003;33:455-456.

    Not in our library10.1038/ng1123

  219. 219.

    Puls I. Distal spinal and bulbar muscular atrophy caused by dynactin mutation. Ann. Neurol. 2005;57:687-694.

    Not in our library10.1002/ana.20468

  220. 220.

    Rao M.V., Campbell J., Palaniappan A., Kumar A., Nixon R.A. Calpastatin inhibits motor neuron death and increases survival of hSOD1(G93A) mice. J. Neurochem. 2016;137:253-265.

    Not in our library10.1111/jnc.13536

  221. 221.

    Reed N.A., Cai D., Blasius T.L., Jih G.T., Meyhofer E., Gaertig J., Verhey K.J. Microtubule acetylation promotes kinesin-1 binding and transport. Curr. Biol. 2006;16:2166-2172.

    Not in our library10.1016/j.cub.2006.09.014

  222. 222.

    Renton A.E., Chio A., Traynor B.J. State of play in amyotrophic lateral sclerosis genetics. Nat. Neurosci. 2014;17:17-23.

    Not in our library10.1038/nn.3584

  223. 223.

    Rodríguez-Martín T., Pooler A.M., Lau D.H., Mórotz G.M., De Vos K.J., Gilley J., Coleman M.P., Hanger D.P. Reduced number of axonal mitochondria and tau hypophosphorylation in mouse P301L tau knockin neurons. Neurobiol. Dis. 2016;85:1-10.

    Not in our library10.1016/j.nbd.2015.10.007

  224. 224.

    Rouleau G.A., Clark A.W., Rooke K., Pramatarova A., Krizus A., Suchowersky O., Julien J.P., Figlewicz D. SOD1 mutation is associated with accumulation of neurofilaments in amyotrophic lateral sclerosis. Ann. Neurol. 1996;39:128-131.

    Not in our library10.1002/ana.410390119

  225. 225.

    Russo G.J., Louie K., Wellington A., Macleod G.T., Hu F., Panchumarthi S., Zinsmaier K.E. Drosophila Miro is required for both anterograde and retrograde axonal mitochondrial transport. J. Neurosci. 2009;29:5443-5455.

    Not in our library10.1523/jneurosci.5417-08.2009

  226. 226.

    Saotome M., Safiulina D., Szabadkai G., Das S., Fransson A., Aspenstrom P., Rizzuto R., Hajnóczky G. Bidirectional Ca2 +-dependent control of mitochondrial dynamics by the Miro GTPase. Proc. Natl. Acad. Sci. U. S. A. 2008;105:20728-20733.

    Not in our library10.1073/pnas.0808953105

  227. 227.

    Sasaki S., Iwata M. Ultrastructural study of synapses in the anterior horn neurons of patients with amyotrophic lateral sclerosis. Neurosci. Lett. 1996;204:53-56.

    Not in our library10.1016/0304-3940(96)12314-4

  228. 228.

    Sasaki S., Iwata M. Mitochondrial alterations in the spinal cord of patients with sporadic amyotrophic lateral sclerosis. J. Neuropathol. Exp. Neurol. 2007;66:10-16.

    Not in our library10.1097/nen.0b013e31802c396b

  229. 229.

    Schäfer M.K., Bellouze S., Jacquier A., Schaller S., Richard L., Mathis S., Vallat J.M., Haase G. Sensory neuropathy in progressive motor neuronopathy (pmn) mice is associated with defects in microtubule polymerization and axonal transport. Brain Pathol. 2016.

    Not in our library10.1111/bpa.12422

  230. 230.
  231. 231.

    Schmieg N., Menendez G., Schiavo G., Terenzio M. Signalling endosomes in axonal transport: travel updates on the molecular highway. Semin. Cell Dev. Biol. 2014;27:32-43.

    Not in our library10.1016/j.semcdb.2013.10.004

  232. 232.

    Schwarzschild M.A., Cole R.L., Hyman S.E. Glutamate, but not dopamine, stimulates stress-activated protein kinase and AP-1-mediated transcription in striatal neurons. J. Neurosci. 1997;17:3455-3466.

    Not in our library10.1523/jneurosci.17-10-03455.1997

  233. 233.

    Schwenk B.M. The FTLD risk factor TMEM106B and MAP6 control dendritic trafficking of lysosomes. EMBO J. 2014;33:450-467.

    Not in our library10.1002/embj.201385857

  234. 234.

    Scoto M. Novel mutations expand the clinical spectrum of DYNC1H1-associated spinal muscular atrophy. Neurology. 2015;84:668-679.

    Not in our library10.1212/wnl.0000000000001269

  235. 235.

    Seitz A. Single-molecule investigation of the interference between kinesin, tau and MAP2c. EMBO J. 2002;21:4896-4905.

    Not in our library10.1093/emboj/cdf503

  236. 236.

    Sendtner M., Holtmann B., Hughes R.A. The response of motoneurons to neurotrophins. Neurochem. Res. 1996;21:831-841.

    Not in our library10.1007/bf02532307

  237. 237.

    Shea T.B., Yabe J.T., Ortiz D., Pimenta A., Loomis P., Goldman R.D., Amin N., Pant H.C. Cdk5 regulates axonal transport and phosphorylation of neurofilaments in cultured neurons. J. Cell Sci. 2004;117:933-941.

    Not in our library10.1242/jcs.00785

  238. 238.

    Shea T.B., Zheng Y.L., Ortiz D., Pant H.C. Cyclin-dependent kinase 5 increases perikaryal neurofilament phosphorylation and inhibits neurofilament axonal transport in response to oxidative stress. J. Neurosci. Res. 2004;76:795-800.

    Not in our library10.1002/jnr.20099

  239. 239.

    Shida T., Cueva J.G., Xu Z., Goodman M.B., Nachury M.V. The major alpha-tubulin K40 acetyltransferase alphaTAT1 promotes rapid ciliogenesis and efficient mechanosensation. Proc. Natl. Acad. Sci. U. S. A. 2010;107:21517-21522.

    Not in our library10.1073/pnas.1013728107

  240. 240.

    Shlevkov E., Kramer T., Schapansky J., LaVoie M.J., Schwarz T.L. Miro phosphorylation sites regulate Parkin recruitment and mitochondrial motility. Proc. Natl. Acad. Sci. U. S. A. 2016;113:E6097-E6106.

    Not in our library10.1073/pnas.1612283113

  241. 241.

    Siklos L., Engelhardt J., Harati Y., Smith R.G., Joo F., Appel S.H. Ultrastructural evidence for altered calcium in motor nerve terminals in amyotropic lateral sclerosis. Ann. Neurol. 1996;39:203-216.

    Not in our library10.1002/ana.410390210

  242. 242.

    Siklós L., Engelhardt J.I., Alexianu M.E., Gurney M.E., Siddique T., Appel S.H. Intracellular calcium parallels motoneuron degeneration in SOD-1 mutant mice. J. Neuropathol. Exp. Neurol. 1998;57:571-587.

    Not in our library10.1097/00005072-199806000-00005

  243. 243.

    Slaughter T., Black M.M. STOP (stable-tubule-only-polypeptide) is preferentially associated with the stable domain of axonal microtubules. J. Neurocytol. 2003;32:399-413.

    Not in our library10.1023/b:neur.0000011334.70648.87

  244. 244.

    Smith B. Exome-wide rare variant analysis identifies TUBA4A mutations associated with familial ALS. Neuron. 2014;84:324-331.

    Not in our library10.1016/j.neuron.2014.09.027

  245. 245.

    Song Y., Kirkpatrick L.L., Schilling A.B., Helseth D.L., Chabot N., Keillor J.W., Johnson G.V., Brady S.T. Transglutaminase and polyamination of tubulin: posttranslational modification for stabilizing axonal microtubules. Neuron. 2013;78:109-123.

    Not in our library10.1016/j.neuron.2013.01.036

  246. 246.

    Song Y., Nagy M., Ni W., Tyagi N.K., Fenton W.A., López-Giráldez F., Overton J.D., Horwich A.L., Brady S.T. Molecular chaperone Hsp110 rescues a vesicle transport defect produced by an ALS-associated mutant SOD1 protein in squid axoplasm. Proc. Natl. Acad. Sci. U. S. A. 2013;110:5428-5433.

    Not in our library10.1073/pnas.1303279110

  247. 247.

    van Spronsen M. TRAK/Milton motor-adaptor proteins steer mitochondrial trafficking to axons and dendrites. Neuron. 2013;77:485-502.

    Not in our library10.1016/j.neuron.2012.11.027

  248. 248.

    Stagi M., Gorlovoy P., Larionov S., Takahashi K., Neumann H. Unloading kinesin transported cargoes from the tubulin track via the inflammatory c-Jun N-terminal kinase pathway. FASEB J. 2006;20:2573-2575.

    Not in our library10.1096/fj.06-6679fje

  249. 249.

    Stamer K., Vogel R., Thies E., Mandelkow E., Mandelkow E.M. Tau blocks traffic of organelles, neurofilaments, and APP vesicles in neurons and enhances oxidative stress. J. Cell Biol. 2002;156:1051-1063.

    Not in our library10.1083/jcb.200108057

  250. 250.

    Stanton R.A., Gernert K.M., Nettles J.H., Aneja R. Drugs that target dynamic microtubules: a new molecular perspective. Med. Res. Rev. 2011;31:443-481.

    Not in our library10.1002/med.20242

  251. 251.

    Stavoe A.K., Hill S.E., Hall D.H., Colón-Ramos D.A. KIF1A/UNC-104 transports ATG-9 to regulate neurodevelopment and autophagy at synapses. Dev. Cell. 2016;38:171-185.

    Not in our library10.1016/j.devcel.2016.06.012

  252. 252.

    Stephen T.L., Higgs N.F., Sheehan D.F., Al Awabdh S., López-Doménech G., Arancibia-Carcamo I.L., Kittler J.T. Miro1 regulates activity-driven positioning of mitochondria within astrocytic processes apposed to synapses to regulate intracellular calcium signaling. J. Neurosci. 2015;35:15996-16011.

    Not in our library10.1523/jneurosci.2068-15.2015

  253. 253.

    Stevenson A., Yates D.M., Manser C., De Vos K.J., Vagnoni A., Leigh P.N., McLoughlin D.M., Miller C.C. Riluzole protects against glutamate-induced slowing of neurofilament axonal transport. Neurosci. Lett. 2009;454:161-164.

    Not in our library10.1016/j.neulet.2009.02.061

  254. 254.
  255. 255.
  256. 256.

    Stowers R.S., Megeath L.J., Gorska-Andrzejak J., Meinertzhagen I.A., Schwarz T.L. Axonal transport of mitochondria to synapses depends on milton, a novel Drosophila protein. Neuron. 2002;36:1063-1077.

    Not in our library10.1016/s0896-6273(02)01094-2

  257. 257.

    Strom A.L., Shi P., Zhang F., Gal J., Kilty R., Hayward L.J., Zhu H. Interaction of amyotrophic lateral sclerosis (ALS)-related mutant copper-zinc superoxide dismutase with the dynein-dynactin complex contributes to inclusion formation. J. Biol. Chem. 2008;283:22795-22805.

    Not in our library10.1074/jbc.m800276200

  258. 258.

    Strong M.J., Volkening K., Hammond R., Yang W., Strong W., Leystra-Lantz C., Shoesmith C. TDP43 is a human low molecular weight neurofilament (hNFL) mRNA-binding protein. Mol. Cell. Neurosci. 2007;35:320-327.

    Not in our library10.1016/j.mcn.2007.03.007

  259. 259.

    Suzuki H., Matsuoka M. The JNK/c-Jun signaling axis contributes to the TDP-43-induced cell death. Mol. Cell. Biochem. 2013;372:241-248.

    Not in our library10.1007/s11010-012-1465-x

  260. 260.

    Swarup V., Phaneuf D., Bareil C., Robertson J., Rouleau G.A., Kriz J., Julien J.P. Pathological hallmarks of amyotrophic lateral sclerosis/frontotemporal lobar degeneration in transgenic mice produced with TDP-43 genomic fragments. Brain. 2011;134:2610-2626.

    Not in our library10.1093/brain/awr159

  261. 261.

    Szebenyi G. Neuropathogenic forms of huntingtin and androgen receptor inhibit fast axonal transport. Neuron. 2003;40:41-52.

    Not in our library10.1016/s0896-6273(03)00569-5

  262. 262.

    Taes I., Timmers M., Hersmus N., Bento-Abreu A., Van Den Bosch L., Van Damme P., Auwerx J., Robberecht W. Hdac6 deletion delays disease progression in the SOD1G93A mouse model of ALS. Hum. Mol. Genet. 2013;22:1783-1790.

    Not in our library10.1093/hmg/ddt028

  263. 263.

    Takahashi S., Kulkarni A.B. Mutant superoxide dismutase 1 causes motor neuron degeneration independent of cyclin-dependent kinase 5 activation by p35 or p25. J. Neurochem. 2004;88:1295-1304.

    Not in our library10.1046/j.1471-4159.2003.02256.x

  264. 264.

    Takeuchi H., Mizuno T., Zhang G., Wang J., Kawanokuchi J., Kuno R., Suzumura A. Neuritic beading induced by activated microglia is an early feature of neuronal dysfunction toward neuronal death by inhibition of mitochondrial respiration and axonal transport. J. Biol. Chem. 2005;280:10444-10454.

    Not in our library10.1074/jbc.m413863200

  265. 265.

    Tan W., Pasinelli P., Trotti D. Role of mitochondria in mutant SOD1 linked amyotrophic lateral sclerosis. Biochim. Biophys. Acta. 2014;1842:1295-1301.

    Not in our library10.1016/j.bbadis.2014.02.009

  266. 266.

    Tanaka Y., Niwa S., Dong M., Farkhondeh A., Wang L., Zhou R., Hirokawa N. The molecular motor KIF1A transports the TrkA neurotrophin receptor and is essential for sensory neuron survival and function. Neuron. 2016;90:1215-1229.

    Not in our library10.1016/j.neuron.2016.05.002

  267. 267.

    Tarrade A. A mutation of spastin is responsible for swellings and impairment of transport in a region of axon characterized by changes in microtubule composition. Hum. Mol. Genet. 2006;15:3544-3558.

    Not in our library10.1093/hmg/ddl431

  268. 268.

    Teuchert M., Fischer D., Schwalenstoecker B., Habisch H.J., Bockers T.M., Ludolph A.C. A dynein mutation attenuates motor neuron degeneration in SOD1(G93A) mice. Exp. Neurol. 2006;198:271-274.

    Not in our library10.1016/j.expneurol.2005.12.005

  269. 269.

    Teuling E., van Dis V., Wulf P.S., Haasdijk E.D., Akhmanova A., Hoogenraad C.C., Jaarsma D. A novel mouse model with impaired dynein/dynactin function develops amyotrophic lateral sclerosis (ALS)-like features in motor neurons and improves lifespan in SOD1-ALS mice. Hum. Mol. Genet. 2008;17:2849-2862.

    Not in our library10.1093/hmg/ddn182

  270. 270.

    Tortarolo M., Veglianese P., Calvaresi N., Botturi A., Rossi C., Giorgini A., Migheli A., Bendotti C. Persistent activation of p38 mitogen-activated protein kinase in a mouse model of familial amyotrophic lateral sclerosis correlates with disease progression. Mol. Cell. Neurosci. 2003;23:180-192.

    Not in our library10.1016/s1044-7431(03)00022-8

  271. 271.

    Toyoshima I., Sugawara M., Kato K., Wada C., Hirota K., Hasegawa K., Kowa H., Sheetz M.P., Masamune O. Kinesin and dynein in spinal spheroids with motor neuron disease. J. Neurol. Sci. 1998;159:38-44.

    Not in our library10.1016/s0022-510x(98)00137-3

  272. 272.

    Trinczek B., Ebneth A., Mandelkow E. Tau regulates the attachment/detachment but not the speed of motors in microtubule-dependent transport of single vesicles and organelles. J. Cell Sci. 1999;112:2355-2367.

    Not in our library10.1242/jcs.112.14.2355

  273. 273.

    Trotta N., Orso G., Rossetto M.G., Daga A., Broadie K. The hereditary spastic paraplegia gene, spastin, regulates microtubule stability to modulate synaptic structure and function. Curr. Biol. 2004;14:1135-1147.

    Not in our library10.1016/j.cub.2004.06.058

  274. 274.
  275. 275.

    UKMND-LiCALS S.G. Lithium in patients with amyotrophic lateral sclerosis (LiCALS): a phase 3 multicentre, randomised, double-blind, placebo-controlled trial. Lancet Neurol. 2013;12:339-345.

    Not in our library10.1016/s1474-4422(13)70037-1

  276. 276.

    Urwin H. Disruption of endocytic trafficking in frontotemporal dementia with CHMP2B mutations. Hum. Mol. Genet. 2010;19:2228-2238.

    Not in our library10.1093/hmg/ddq100

  277. 277.

    Vagnoni A., Hoffmann P.C., Bullock S.L. Reducing Lissencephaly-1 levels augments mitochondrial transport and has a protective effect in adult Drosophila neurons. J. Cell Sci. 2016;129:178-190.

    Not in our library10.1242/jcs.179184

  278. 278.

    Van Deerlin V.M. Common variants at 7p21 are associated with frontotemporal lobar degeneration with TDP-43 inclusions. Nat. Genet. 2010;42:234-239.

    Not in our library10.1038/ng.536

  279. 279.
  280. 280.

    Vilariño-Güell C. Characterization of DCTN1 genetic variability in neurodegeneration. Neurology. 2009;72:2024-2028.

    Not in our library10.1212/wnl.0b013e3181a92c4c

  281. 281.

    Vogel F., Bornhövd C., Neupert W., Reichert A.S. Dynamic subcompartmentalization of the mitochondrial inner membrane. J. Cell Biol. 2006;175:237-247.

    Not in our library10.1083/jcb.200605138

  282. 282.

    Wagner U., Utton M., Gallo J.M., Miller C.C. Cellular phosphorylation of tau by GSK-3 beta influences tau binding to microtubules and microtubule organisation. J. Cell Sci. 1996;109:1537-1543.

    Not in our library10.1242/jcs.109.6.1537

  283. 283.

    Wang X., Schwarz T.L. The mechanism of Ca2 +-dependent regulation of kinesin-mediated mitochondrial motility. Cell. 2009;136:163-174.

    Not in our library10.1016/j.cell.2008.11.046

  284. 284.

    Wang X., Winter D., Ashrafi G., Schlehe J., Wong Y.L., Selkoe D., Rice S., Steen J., LaVoie M.J., Schwarz T.L. PINK1 and Parkin target Miro for phosphorylation and degradation to arrest mitochondrial motility. Cell. 2011;147:893-906.

    Not in our library10.1016/j.cell.2011.10.018

  285. 285.

    Wang W., Li L., Lin W.L., Dickson D.W., Petrucelli L., Zhang T., Wang X. The ALS disease-associated mutant TDP-43 impairs mitochondrial dynamics and function in motor neurons. Hum. Mol. Genet. 2013;22:4706-4719.

    Not in our library10.1093/hmg/ddt319

  286. 286.

    Wang W. The inhibition of TDP-43 mitochondrial localization blocks its neuronal toxicity. Nat. Med. 2016;22:869-878.

    Not in our library10.1038/nm.4130

  287. 287.

    Warita H., Itoyama Y., Abe K. Selective impairment of fast anterograde axonal transport in the peripheral nerves of asymptomatic transgenic mice with a G93A mutant SOD1 gene. Brain Res. 1999;819:120-131.

    Not in our library10.1016/s0006-8993(98)01351-1

  288. 288.
  289. 289.
  290. 290.

    Webster C.P., Smith E.F., Grierson A.J., De Vos K.J. C9orf72 plays a central role in Rab GTPase-dependent regulation of autophagy. Small GTPases. 2016;1-10.

    Not in our library10.1080/21541248.2016.1240495

  291. 291.

    Weihofen A., Thomas K.J., Ostaszewski B.L., Cookson M.R., Selkoe D.J. Pink1 forms a multiprotein complex with Miro and Milton, linking Pink1 function to mitochondrial trafficking. Biochemistry. 2009;48:2045-2052.

    Not in our library10.1021/bi8019178

  292. 292.

    Williamson T.L., Cleveland D.W. Slowing of axonal transport is a very early event in the toxicity of ALS-linked SOD1 mutants to motor neurons. Nat. Neurosci. 1999;2:50-56.

    Not in our library10.1038/4553

  293. 293.

    Wood J.D., Landers J.A., Bingley M., McDermott C.J., Thomas-McArthur V., Gleadall L.J., Shaw P.J., Cunliffe V.T. The microtubule-severing protein Spastin is essential for axon outgrowth in the zebrafish embryo. Hum. Mol. Genet. 2006;15:2763-2771.

    Not in our library10.1093/hmg/ddl212

  294. 294.

    Xia C.H., Roberts E.A., Her L.S., Liu X., Williams D.S., Cleveland D.W., Goldstein L.S. Abnormal neurofilament transport caused by targeted disruption of neuronal kinesin heavy chain KIF5A. J. Cell Biol. 2003;161:55-66.

    Not in our library10.1083/jcb.200301026

  295. 295.

    Xia Q., Wang H., Zhang Y., Ying Z., Wang G. Loss of TDP-43 inhibits amyotrophic lateral sclerosis-linked mutant SOD1 aggresome formation in an HDAC6-dependent manner. J. Alzheimers Dis. 2015;45:373-386.

    Not in our library10.3233/jad-142244

  296. 296.

    Xia Q. TDP-43 loss of function increases TFEB activity and blocks autophagosome-lysosome fusion. EMBO J. 2015;35:121-142.

    Not in our library10.15252/embj.201591998

  297. 297.

    Xiao S., McLean J., Robertson J. Neuronal intermediate filaments and ALS: a new look at an old question. Biochim. Biophys. Acta. 2006;1762:1001-1012.

    Not in our library10.1016/j.bbadis.2006.09.003

  298. 298.

    Xu Y.F. Wild-type human TDP-43 expression causes TDP-43 phosphorylation, mitochondrial aggregation, motor deficits, and early mortality in transgenic mice. J. Neurosci. 2010;30:10851-10859.

    Not in our library10.1523/jneurosci.1630-10.2010

  299. 299.
  300. 300.

    Yadav P. Neurofilament depletion improves microtubule dynamics via modulation of Stat3/stathmin signaling. Acta Neuropathol. 2016;132:93-110.

    Not in our library10.1007/s00401-016-1564-y

  301. 301.

    Yan Q., Elliott J.L., Matheson C., Sun J., Zhang L., Mu X., Rex K.L., Snider W.D. Influences of neurotrophins on mammalian motoneurons in vivo. J. Neurobiol. 1993;24:1555-1577.

    Not in our library10.1002/neu.480241202

  302. 302.

    Yan S., Guo C., Hou G., Zhang H., Lu X., Williams J.C., Polenova T. Atomic-resolution structure of the CAP-Gly domain of dynactin on polymeric microtubules determined by magic angle spinning NMR spectroscopy. Proc. Natl. Acad. Sci. U. S. A. 2015;112:14611-14616.

    Not in our library10.1073/pnas.1509852112

  303. 303.

    Yang W., Leystra-Lantz C., Strong M.J. Upregulation of GSK3beta expression in frontal and temporal cortex in ALS with cognitive impairment (ALSci). Brain Res. 2008;1196:131-139.

    Not in our library10.1016/j.brainres.2007.12.031

  304. 304.

    Yang M., Liang C., Swaminathan K., Herrlinger S., Lai F., Shiekhattar R., Chen J.-F. A C9ORF72/SMCR8-containing complex regulates ULK1 and plays a dual role in autophagy. Sci. Adv. 2016;2.

    Not in our library10.1126/sciadv.1601167

  305. 305.

    d'Ydewalle C., Krishnan J., Chiheb D.M., Van Damme P., Irobi J., Kozikowski A.P., Vanden Berghe P., Timmerman V., Robberecht W., Van Den Bosch L. HDAC6 inhibitors reverse axonal loss in a mouse model of mutant HSPB1-induced Charcot-Marie-Tooth disease. Nat. Med. 2011;17:968-974.

    Not in our library10.1038/nm.2396

  306. 306.

    Yonekawa Y., Harada A., Okada Y., Funakoshi T., Kanai Y., Takei Y., Terada S., Noda T., Hirokawa N. Defect in synaptic vesicle precursor transport and neuronal cell death in KIF1A motor protein-deficient mice. J. Cell Biol. 1998;141:431-441.

    Not in our library10.1083/jcb.141.2.431

  307. 307.

    Yu L., Guan Y., Wu X., Chen Y., Liu Z., Du H., Wang X. Wnt Signaling is altered by spinal cord neuronal dysfunction in amyotrophic lateral sclerosis transgenic mice. Neurochem. Res. 2013;38:1904-1913.

    Not in our library10.1007/s11064-013-1096-y

  308. 308.

    Zala D., Hinckelmann M.V., Yu H., Lyra da Cunha M.M., Liot G., Cordelieres F.P., Marco S., Saudou F. Vesicular glycolysis provides on-board energy for fast axonal transport. Cell. 2013;152:479-491.

    Not in our library10.1016/j.cell.2012.12.029

  309. 309.

    Zhan L., Xie Q., Tibbetts R.S. Opposing roles of p38 and JNK in a Drosophila model of TDP-43 proteinopathy reveal oxidative stress and innate immunity as pathogenic components of neurodegeneration. Hum. Mol. Genet. 2015;24:757-772.

    Not in our library10.1093/hmg/ddu493

  310. 310.

    Zhang F., Zhu H. Intracellular conformational alterations of mutant SOD1 and the implications for fALS-associated SOD1 mutant induced motor neuron cell death. Biochim. Biophys. Acta. 2006;1760:404-414.

    Not in our library10.1016/j.bbagen.2005.11.024

  311. 311.

    Zhang B., Tu P., Abtahian F., Trojanowski J.Q., Lee V.M. Neurofilaments and orthograde transport are reduced in ventral root axons of transgenic mice that express human SOD1 with a G93A mutation. J. Cell Biol. 1997;139:1307-1315.

    Not in our library10.1083/jcb.139.5.1307

  312. 312.

    Zhang B., Higuchi M., Yoshiyama Y., Ishihara T., Forman M.S., Martinez D., Joyce S., Trojanowski J.Q., Lee V.M. Retarded axonal transport of R406W mutant tau in transgenic mice with a neurodegenerative tauopathy. J. Neurosci. 2004;24:4657-4667.

    Not in our library10.1523/jneurosci.0797-04.2004

  313. 313.

    Zhang F., Strom A.L., Fukada K., Lee S., Hayward L.J., Zhu H. Interaction between familial amyotrophic lateral sclerosis (ALS)-linked SOD1 mutants and the dynein complex. J. Biol. Chem. 2007;282:16691-16699.

    Not in our library10.1074/jbc.m609743200

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    Zhu Y.B., Sheng Z.H. Increased axonal mitochondrial mobility does not slow amyotrophic lateral sclerosis (ALS)-like disease in mutant SOD1 mice. J. Biol. Chem. 2011;286:23432-23440.

    Not in our library10.1074/jbc.m111.237818

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