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Orai1 expression and function in vascular smooth muscle cells
Author(s) -
Li Jing,
Jairaman Amit,
Sukumar Piruthivi,
Porter Karen,
Beech David
Publication year - 2008
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.22.1_supplement.965.20
Subject(s) - orai1 , microbiology and biotechnology , thapsigargin , vascular smooth muscle , cell migration , calcium channel , voltage dependent calcium channel , biology , stim1 , calcium , chemistry , cell , endocrinology , biochemistry , smooth muscle , endoplasmic reticulum , organic chemistry
Recent studies suggest TRPC5 is a component of calcium‐entry channels that help drive vascular smooth muscle cell migration (Xu et al 2006, Circ Res 98, 1381–9). Here we investigated another type of channel protein (Orai1) which is distinct from the TRP proteins and has been suggested to have pivotal roles in calcium‐entry of lymphocytes (Hogan & Rao 2007, Trends Biochem Sci 32, 235–45). Our experiments focused on proliferating vascular smooth muscle cells of the human saphenous vein. Quantitative RT‐PCR revealed high levels of mRNA encoding Orai1 and its homologues Orai2 and Orai3. Calcium‐entry was measured in the cells after store‐depletion with thapsigargin and using fura‐2 indicator dye on a real‐time 96‐well plate reader. RNAi knock‐down of Orai1 suppressed calcium‐entry, while knock‐down of Orai2 or Orai3 had no effect. Functional relevance was studied using modified Boyden chamber assays to quantify cell migration (chemotaxis) and invasion (through basement membrane matrix) in the absence of store‐depletion. Knock‐down of Orai1 markedly suppressed migration and invasion. Invasion is facilitated by secretion of matrix metalloproteinases (eg MMP‐2) but knock‐down of Orai1 had no significant effect on secretion of MMP‐2. The data suggest Orai1 is a novel calcium channel protein of vascular smooth muscle cells with important roles in cell motility. Supported by the British Heart Foundation and Wellcome Trust.