A calcium/cAMP signaling loop at the ORAI1 mouth drives channel inactivation to shape NFAT induction

ORAI1 constitutes the store-operated Ca 2+ release-activated Ca 2+ (CRAC) channel crucial for life. Whereas ORAI1 activation by Ca 2+ -sensing STIM proteins is known, still obscure is how ORAI1 is turned off through Ca 2+ -dependent inactivation (CDI), protecting against Ca 2+ toxicity. Here we identify a spatially-restricted Ca 2+ /cAMP signaling crosstalk critical for mediating CDI. Binding of Ca 2+ -activated adenylyl cyclase 8 (AC8) to the N-terminus of ORAI1 positions AC8 near the mouth of ORAI1 for sensing Ca 2+ . Ca 2+ permeating ORAI1 activates AC8 to generate cAMP and activate PKA. PKA, positioned by AKAP79 near ORAI1, phosphorylates serine-34 in ORAI1 pore extension to induce CDI whereas recruitment of the phosphatase calcineurin antagonizes the effect of PKA. Notably, CDI shapes ORAI1 cytosolic Ca 2+ signature to determine the isoform and degree of NFAT activation. Thus, we uncover a mechanism of ORAI1 inactivation, and reveal a hitherto unappreciated role for inactivation in shaping cellular Ca 2+ signals and NFAT activation.

Abstract licence: CC BY-NC-ND

1. 51.

   NFAT control of immune function: New Frontiers for an Abiding Trooper · 2018

54 more references, whose wording the paper’s licence keeps private.

• The native ORAI channel trio underlies the diversity of Ca2+ signaling events · 2020

A person counts once a day per paper. We keep no cookie and no address: a reader is a hash that changes every day. Any month under five reads shows no number.