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Caveolin‐1 regulates intracellular Ca 2+ in human airway smooth muscle
Author(s) -
Thompson Michael Allan,
Vaa Brianna,
Matabdin Ihaab,
Peterson Tim,
He Tongrong,
Pabelick Christina M.,
Prakash Y. S.
Publication year - 2007
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.21.6.a960-b
Subject(s) - intracellular , caveolin 1 , microbiology and biotechnology , smooth muscle , caveolin 3 , airway , chemistry , anatomy , biology , caveolae , medicine , endocrinology , signal transduction , anesthesia
Intracellular calcium ([Ca 2+ ] i ) in airway smooth muscle (ASM) is key to contractility. In vascular smooth muscle, specialized plasma membrane microdomains (caveolae) expressing the scaffolding protein caveolin are thought to facilitate signal transduction. We hypothesized that caveolae in ASM are important in mediating agonist induced [Ca 2+ ] i responses. In human ASM cells, fluorescence confocal microscopy as well as Western blot analyses were used to determine expression and co‐localization of agonist receptors (M 3 muscarinic, bradykinin, histamine) as well as TRPC proteins with caveolin‐1. The muscle‐specific caveolin‐3 was barely detectable in these cells, while caveolin‐2 (usually associated with caveolin‐1) was present. Transfection of ASM cell with 50nM caveolin‐1 siRNA significantly knocked down caveolin‐1 expression (~75%), but caveolin‐2 expression did not decrease. In ASM cells loaded with 5μM fura2, [Ca 2+ ] i responses to 10nM bradykinin and 10μM histamine, but not 1μM ACh, were attenuated following disruption of caveolae by the cholesterol chelating drug, methyl‐β‐cyclodextrin (10mM). Transfection of caveolin‐1 siRNA significantly blunted [Ca 2+ ] i responses to bradykinin and histamine, but not ACh. Store‐operated Ca 2+ entry was also significantly blunted by cyclodextrin as well as caveolin‐1 knockdown. These results indicate that caveolae are present in ASM and contribute to regulation of agonist induced [Ca 2+ ] i responses, most likely via caveolin‐1. Supported by Clinical Research grants from the Mayo Foundation, and by the Foundation for Anesthesia Education and Research.