Evidence that Orai1 does not contribute to store-operated TRPC1 channels in vascular smooth muscle cells

Shi, Jian, Miralles, Francesc, Kinet, Jean Pierre, Birnbaumer, Lutz, Large, William A. and Albert, Anthony P. (2017) Evidence that Orai1 does not contribute to store-operated TRPC1 channels in vascular smooth muscle cells. Channels, 11 (4). pp. 329-339. ISSN 1933-6950

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Abstract

Ca2+-permeable store-operated channels (SOCs) mediate Ca2+ entry pathways which are involved in many cellular functions such as contraction, growth, and proliferation. Prototypical SOCs are formed of Orai1 proteins and are activated by the endo/sarcoplasmic reticulum Ca2+ sensor stromal interaction molecule 1 (STIM1). There is considerable debate about whether canonical transient receptor potential 1 (TRPC1) proteins also form store-operated channels (SOCs), and if they do, is Orai1 involved. We recently showed that stimulation of TRPC1-based SOCs involves store depletion inducing STIM1-evoked Gαq/PLCβ1 activity in contractile vascular smooth muscle cells (VSMCs). Therefore the present work investigates the role of Orai1 in activation of TRPC1-based SOCs in freshly isolated mesenteric artery VSMCs from wild-type (WT) and Orai1−/− mice. Store-operated whole-cell and single channel currents recorded from WT and Orai1−/− VSMCs had similar properties, with relatively linear current-voltage relationships, reversal potentials of about +20mV, unitary conductances of about 2pS, and inhibition by anti-TRPC1 and anti-STIM1 antibodies. In Orai1−/− VSMCs, store depletion induced PLCβ1 activity measured with the fluorescent phosphatidylinositol 4,5-bisphosphate/inositol 1,4,5-trisphosphate biosensor GFP-PLCδ1-PH, which was prevented by knockdown of STIM1. In addition, in Orai1−/− VSMCs, store depletion induced translocation of STIM1 from within the cell to the plasma membrane where it formed STIM1-TRPC1 interactions at discrete puncta-like sites. These findings indicate that activation of TRPC1-based SOCs through a STIM1-activated PLCβ1 pathway are likely to occur independently of Orai1 proteins, providing evidence that TRPC1 channels form genuine SOCs in VSMCs with a contractile phenotype.

Item Type:	Article
Additional Information:	Funding Information: We would like to thank Dr Paris Ataliotis for his assistance with genotyping. This work was supported by the Biotechnology and Biological Sciences Research Council (BB/J007226/1 and BB/M018350/1 to APA) and was also supported in part by the NIH Intramural Research Program (Project Z01-ES-101684 to L.B). Funding Information: This work was supported by the Biotechnology and Biological Sciences Research Council (BB/J007226/1 and BB/M018350/1 to APA) and was also supported in part by the NIH Intramural Research Program (Project Z01-ES-101684 to L.B). Publisher Copyright: © 2017 St. George's, University of London. Published with license by Taylor & Francis.
Uncontrolled Keywords:	orai1,plc,stim1,store-operated,trpc1,vascular smooth muscle,biophysics,biochemistry ,/dk/atira/pure/subjectarea/asjc/1300/1304
Faculty \ School:	Faculty of Medicine and Health Sciences > Norwich Medical School
Related URLs:	http://www.scopus.com/inward/record.url?...
Depositing User:	LivePure Connector
Date Deposited:	29 Oct 2024 09:30
Last Modified:	28 Jan 2025 23:39
URI:	https://ueaeprints.uea.ac.uk/id/eprint/97246
DOI:

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