Dataset Information

Activation of TRPC1 by STIM1 in ER-PM microdomains involves release of the channel from its scaffold caveolin-1.

ABSTRACT: Store-operated Ca(2+) entry (SOCE) is activated by redistribution of STIM1 into puncta in discrete ER-plasma membrane junctional regions where it interacts with and activates store-operated channels (SOCs). The factors involved in precise targeting of the channels and their retention at these specific microdomains are not yet defined. Here we report that caveolin-1 (Cav1) is a critical plasma membrane scaffold that retains TRPC1 within the regions where STIM1 puncta are localized following store depletion. This enables the interaction of TRPC1 with STIM1 that is required for the activation of TRPC1-SOCE. Silencing Cav1 in human submandibular gland (HSG) cells decreased plasma membrane retention of TRPC1, TRPC1-STIM1 clustering, and consequently reduced TRPC1-SOCE, without altering STIM1 puncta. Importantly, activation of TRPC1-SOCE was associated with an increase in TRPC1-STIM1 and a decrease in TRPC1-Cav1 clustering. Consistent with this, overexpression of Cav1 decreased TRPC1-STIM1 clustering and SOCE, both of which were recovered when STIM1 was expressed at higher levels relative to Cav1. Silencing STIM1 or expression of DeltaERM-STIM1 or STIM1((684)EE(685)) mutant prevented dissociation of TRPC1-Cav1 and activation of TRPC1-SOCE. However expression of TRPC1-((639)KK(640)) with STIM1((684)EE(685)) restored function and the dissociation of TRPC1 from Cav1 in response to store depletion. Further, conditions that promoted TRPC1-STIM1 clustering and TRPC1-SOCE elicited corresponding changes in SOCE-dependent NFkB activation and cell proliferation. Together these data demonstrate that Cav1 is a critical plasma membrane scaffold for inactive TRPC1. We suggest that activation of TRPC1-SOC by STIM1 mediates release of the channel from Cav1.

SUBMITTER: Pani B

PROVIDER: S-EPMC2785296 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Activation of TRPC1 by STIM1 in ER-PM microdomains involves release of the channel from its scaffold caveolin-1.

Pani Biswaranjan B Ong Hwei Ling HL Brazer So-Ching W SC Liu Xibao X Rauser Kristina K Singh Brij B BB Ambudkar Indu S IS

Proceedings of the National Academy of Sciences of the United States of America 20091106 47

Store-operated Ca(2+) entry (SOCE) is activated by redistribution of STIM1 into puncta in discrete ER-plasma membrane junctional regions where it interacts with and activates store-operated channels (SOCs). The factors involved in precise targeting of the channels and their retention at these specific microdomains are not yet defined. Here we report that caveolin-1 (Cav1) is a critical plasma membrane scaffold that retains TRPC1 within the regions where STIM1 puncta are localized following store ...[more]

PMID: 19897728

Similar Datasets

Project description:Ca(2+)-release-activated Ca(2+) (CRAC) channels generate sustained Ca(2+) signals that are essential for a range of cell functions, including antigen-stimulated T lymphocyte activation and proliferation. Recent studies have revealed that the depletion of Ca(2+) from the endoplasmic reticulum (ER) triggers the oligomerization of stromal interaction molecule 1 (STIM1), the ER Ca(2+) sensor, and its redistribution to ER-plasma membrane (ER-PM) junctions where the CRAC channel subunit ORAI1 accumulates in the plasma membrane and CRAC channels open. However, how the loss of ER Ca(2+) sets into motion these coordinated molecular rearrangements remains unclear. Here we define the relationships among [Ca(2+)](ER), STIM1 redistribution and CRAC channel activation and identify STIM1 oligomerization as the critical [Ca(2+)](ER)-dependent event that drives store-operated Ca(2+) entry. In human Jurkat leukaemic T cells expressing an ER-targeted Ca(2+) indicator, CRAC channel activation and STIM1 redistribution follow the same function of [Ca(2+)](ER), reaching half-maximum at approximately 200 microM with a Hill coefficient of approximately 4. Because STIM1 binds only a single Ca(2+) ion, the high apparent cooperativity suggests that STIM1 must first oligomerize to enable its accumulation at ER-PM junctions. To assess directly the causal role of STIM1 oligomerization in store-operated Ca(2+) entry, we replaced the luminal Ca(2+)-sensing domain of STIM1 with the 12-kDa FK506- and rapamycin-binding protein (FKBP12, also known as FKBP1A) or the FKBP-rapamycin binding (FRB) domain of the mammalian target of rapamycin (mTOR, also known as FRAP1). A rapamycin analogue oligomerizes the fusion proteins and causes them to accumulate at ER-PM junctions and activate CRAC channels without depleting Ca(2+) from the ER. Thus, STIM1 oligomerization is the critical transduction event through which Ca(2+) store depletion controls store-operated Ca(2+) entry, acting as a switch that triggers the self-organization and activation of STIM1-ORAI1 clusters at ER-PM junctions.

Dataset Information

Activation of TRPC1 by STIM1 in ER-PM microdomains involves release of the channel from its scaffold caveolin-1.

Publications

Activation of TRPC1 by STIM1 in ER-PM microdomains involves release of the channel from its scaffold caveolin-1.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets