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TRPC1 and Orai1 interact with STIM1 and Mediate Capacitative Calcium Entry Activated by Acute Hypoxia in Mouse Pulmonary Arterial Smooth Muscle Cells
Author(s) -
Ng Lih Chyuan,
O'Neill Kathryn G.,
French Dominique,
Airey Judith A.,
Singer Cherie A.,
Tian Honglin,
Shen Xiao-Ming,
Hume Joseph R.
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.700.5
Subject(s) - orai1 , trpc1 , hypoxia (environmental) , stim1 , transfection , chemistry , microbiology and biotechnology , biology , endoplasmic reticulum , transient receptor potential channel , biochemistry , oxygen , receptor , gene , organic chemistry
The present study aimed to determine if TRPC1 and Orai1 interact with STIM1 and mediate CCE caused by acute hypoxia in mouse PASMCs. In primary cultured PASMCs loaded with fura‐2, acute hypoxia caused a transient followed by a sustained rise in intracellular Ca 2+ concentration ([Ca 2+ ] i ). Acute hypoxia also increased the rate of Mn 2+ quench of fura‐2 fluorescence that was inhibited by SKF 96365, Ni 2+ , La 3+ and Gd 3 , exhibiting pharmacological properties characteristic of CCE. The nifedipine‐insensitive rise in [Ca 2+ ] i and the increase in Mn 2+ quench rate were both inhibited in cells treated with TRPC1 antibody, in cells transfected with STIM1 siRNA and cells transfected with Orai1 siRNA. Moreover, overexpression of STIM1 resulted in a marked increase in [Ca 2+ ] i and Mn 2+ quench rate caused by acute hypoxia, and they were reduced in cells treated with TRPC1 antibody and cells treated with Orai1 siRNA. Furthermore, TRPC1 and Orai1 co‐immunoprecipitate with STIM1 and the precipitation levels of TRPC1 and Orai1 were increased in cells exposed to acute hypoxia. Immunostaining showed co‐localizations of TRPC1‐STIM1 and Orai1‐STIM1, and the co‐localizations of these proteins were more apparent in acute hypoxia. These data provide direct evidence that TRPC1 and Orai1 channels mediate CCE through activation of STIM1 in mouse PASMCs in acute hypoxia. [Supported by HL49254 (JR Hume) and AHA Scientist Development Grant (LC Ng)]