Caveolin-1 and force regulation in porcine airway smooth muscle

Sathish V, Yang B, Meuchel LW, VanOosten SK, Ryu AJ, Thompson MA, Prakash YS, Pabelick CM. Caveolin-1 and force regulation in porcine airway smooth muscle. Am J Physiol Lung Cell Mol Physiol 300: L920-L929, 2011. First published March 18, 2011; doi:10.1152/ajplung.00322.2010.-Caveolae are specialized membrane microdomains expressing the scaffolding protein caveolin-1. We recently demonstrated the presence of caveolae in human airway smooth muscle (ASM) and the contribution of caveolin-1 to intracellular calcium ([Ca2+](i)) regulation. In the present study, we tested the hypothesis that caveolin-1 regulates ASM contractility. We examined the role of caveolins in force regulation of porcine ASM under control conditions as well as TNF-alpha-induced airway inflammation. In porcine ASM strips, exposure to 10 mM methyl-beta-cyclodextrin (CD) or 5 mu M of the caveolin-1 specific scaffolding domain inhibitor peptide (CSD) resulted in time-dependent decrease in force responses to 1 mu M ACh. Overnight exposure to the cytokine TNF-alpha (50 ng/ml) accelerated and increased caveolin-1 expression and enhanced force responses to ACh. Suppression of caveolin-1 with small interfering RNA mimicked the effects of CD or CSD. Regarding mechanisms by which caveolae contribute to contractile changes, inhibition of MAP kinase with 10 mu M PD98059 did not alter control or TNF-alpha-induced increases in force responses to ACh. However, inhibiting RhoA with 100 mu M fasudil or 10 mu M Y27632 resulted in significant decreases in force responses, with lesser effects in TNF-alpha exposed samples. Furthermore, Ca2+ sensitivity for force generation was substantially reduced by fasudil or Y27632, an effect even more enhanced in the absence of caveolin-1 signaling. Overall, these results indicate that caveolin-1 is a critical player in enhanced ASM contractility with airway inflammation.