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.External 2231691f894ba696de1310221b0a0dbbb31a7251e75115c265587c3d9d5f507c

Cioffi, D. L., Wu, S., Chen, H., Alexeyev, M., St Croix, C. M., Pitt, B. R., Uhlig, S., Stevens, T.,
["Department of Biochemistry and Molecular Biology, University of South Alabama College of Medicine, Mobile, AL 36688, USA. dlcioffi@ usouthal.edu"]
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. Forster 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: 22534489External 2231691f894ba696de1310221b0a0dbbb31a7251e75115c265587c3d9d5f507c
Screening Toggle 893349bafcc528f8346c51dc3420151d67b0126b2c122dd1017121c03fa0f69b
  Experimental screening Non-experimental screening Reference
TRP channel construct Interactor source
TRP channel Interactor Method Species Region Species Organ/tissue Sample type
TRPC1 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Protein 4.1 Inference Prediction 22534489
(Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
Validation: In vivo validation Toggle 893349bafcc528f8346c51dc3420151d67b0126b2c122dd1017121c03fa0f69b
  Assay with endogenous proteins Assay with overexpressed proteins Reference
Cell or tissue Cell or tissue TRP channel construct Interactor construct
TRP channel Interactor Method Species Region Species Region
TRPC1 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Protein 4.1 Co-immunoprecipitation Rat pumonary aortic endothelial cell 22534489
TRPC1 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 TRPC4 Fluorescence resonance energy transfer Rat pumonary aortic endothelial cell 22534489
TRPC4 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 Protein 4.1 Co-immunoprecipitation Rat pumonary aortic endothelial cell 22534489
TRPC4 Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4 TRPC1 Fluorescence resonance energy transfer Rat pumonary aortic endothelial cell 22534489
(Link 2bd4d11adb659cddf58197a94e201f0a44c55d8d7cb427c624971b42e122c0a4: click the arrow icon to show interactions only between the corresponding TRP channel and the interactor)
TRP / Interactor

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