Orai Proteins Interact with TRPC Channels and Confer Responsiveness to Store Depletion
Overview
Authors
Affiliations
The TRPC (C-type transient receptor potential) class of ion channels has been hypothesized to participate in store-operated Ca(2+) entry (SOCE). Recently, however, STIM1 and Orai1 proteins have been proposed to form SOCE channels. Whether TRPCs participate in SOCE that is dependent on or regulated by Orai has not been explored. Here we show that Orai1 physically interacts with the N and C termini of TRPC3 and TRPC6, and that in cells overexpressing either TRPC3 or TRPC6 in a store-depletion insensitive manner, these TRPCs become sensitive to store depletion upon expression of an exogenous Orai. Thus, Orai-1, -2, and -3 enhanced thapsigargin-induced calcium entry by 50-150% in cells stably overexpressing either TRPC3 or TRPC6. Orai1 expression had no significant effect on endogenous, thapsigargin-induced calcium entry in wild-type cells (HEK-293, COS1), in HEK cells expressing a thapsigargin-sensitive variant of TRPC3 (TRPC3a), or in HEK cells overexpressing another membrane protein, V1aR. Single-channel cation currents present in membrane patches of TRPC3-overexpressing cells were suppressed by expression of Orai1. We propose that Orai proteins by interacting with TRPCs act as regulatory subunits that confer STIM1-mediated store depletion sensitivity to these channels.
Store-Operated Ca Entry in Fibrosis and Tissue Remodeling.
Abdelnaby A, Trebak M Contact (Thousand Oaks). 2024; 7:25152564241291374.
PMID: 39659877 PMC: 11629433. DOI: 10.1177/25152564241291374.
Genetic evidence against involvement of TRPC proteins in SOCE, ROCE, and CRAC channel function.
Susperreguy S, Yamashita M, Choi C, Liao Y, Burch L, Blankenship T Proc Natl Acad Sci U S A. 2024; 121(49):e2411389121.
PMID: 39602257 PMC: 11626178. DOI: 10.1073/pnas.2411389121.
Physiological functions of calcium signaling via Orai1 in cancer.
Umemura M, Nakakaji R, Ishikawa Y J Physiol Sci. 2023; 73(1):21.
PMID: 37759164 PMC: 10717067. DOI: 10.1186/s12576-023-00878-0.
Estrogenic Modulation of Ionic Channels, Pumps and Exchangers in Airway Smooth Muscle.
Romero-Martinez B, Sommer B, Solis-Chagoyan H, Calixto E, Aquino-Galvez A, Jaimez R Int J Mol Sci. 2023; 24(9).
PMID: 37175587 PMC: 10178541. DOI: 10.3390/ijms24097879.
Reorganization and Suppression of Store-Operated Calcium Entry in Podocytes of Type 2 Diabetic Rats.
Gusev K, Shalygin A, Kolesnikov D, Shuyskiy L, Makeenok S, Glushankova L Int J Mol Sci. 2023; 24(8).
PMID: 37108424 PMC: 10139047. DOI: 10.3390/ijms24087259.