Display Settings:

Format

Send to:

Choose Destination
We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Circ Res. 2012 May 25;110(11):1435-44. doi: 10.1161/CIRCRESAHA.112.269506. Epub 2012 Apr 24.

Orai1 determines calcium selectivity of an endogenous TRPC heterotetramer channel.

Author information

  • 1Department of Biochemistry and Molecular Biology, University of South Alabama College of Medicine, Mobile, AL 36688, USA. dlcioffi@ usouthal.edu

Abstract

RATIONALE:

Canonical transient receptor potential 4 (TRPC4) contributes to the molecular composition of a channel encoding for a calcium selective store-operated current, I(SOC), whereas Orai1 critically comprises a channel encoding for the highly selective calcium release activated calcium current, I(CRAC). However, Orai1 may interact with TRPC proteins and influence their activation and permeation characteristics. Endothelium expresses both TRPC4 and Orai1, and it remains unclear as to whether Orai1 interacts with TRPC4 and contributes to calcium permeation through the TPRC4 channel.

OBJECTIVE:

We tested the hypothesis that Orai1 interacts with TRPC4 and contributes to the channel's selective calcium permeation important for endothelial barrier function.

METHODS AND RESULTS:

A novel method to purify the endogenous TRPC4 channel and probe for functional interactions was developed, using TRPC4 binding to protein 4.1 as bait. Isolated channel complexes were conjugated to anti-TRPC protein antibodies labeled with cy3-cy5 pairs. Förster Resonance Energy Transfer among labeled subunits revealed the endogenous protein alignment. One TRPC1 and at least 2 TRPC4 subunits constituted the endogenous channel (TRPC1/4). Orai1 interacted with TRPC4. Conditional Orai1 knockdown reduced the probability for TRPC1/4 channel activation and converted it from a calcium-selective to a nonselective channel, an effect that was rescued on Orai1 reexpression. Loss of Orai1 improved endothelial cell barrier function.

CONCLUSION:

Orai1 interacts with TRPC4 in the endogenous channel complex, where it controls TRPC1/4 activation and channel permeation characteristics, including calcium selectivity, important for control of endothelial cell barrier function.

PMID:
22534489
[PubMed - indexed for MEDLINE]
PMCID:
PMC3388001
Free PMC Article

Images from this publication.See all images (6)Free text

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk