Rho signaling regulates pannexin 1-mediated ATP release from airway epithelia.

LUCIA SEMINARIO-VIDAL; SEIKO F. OKADA; JULIANA I. SESMA; SILVIA M. KREDA; CATHARINA A. VAN HEUSDEN; YUNXIANG ZHU; LISA C. JONES; WANDA K. ONEAL; SILVIA PENUELA; DALE W. LAIRD; RICHARD C. BOUCHER; EDUARDO R. LAZAROWSKI

JOURNAL OF BIOLOGICAL CHEMISTRY

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Lugar: Bethesda, Maryland; Año: 2011 vol. 286 p. 26277 - 26286

0021-9258

ATP released from airway epithelial cells promotes puri- nergic receptor-regulated mucociliary clearance activities necessary for innate lung defense. Cell swelling-induced membrane stretch/strain is a common stimulus that pro- motes airway epithelial ATP release, but the mechanisms transducing cell swelling into ATP release are incompletely understood. Using knockdown and knockout approaches, we tested the hypothesis that pannexin 1 mediates ATP release from hypotonically swollen airway epithelia and investigated mechanisms regulating this activity. Well differentiated pri- mary cultures of human bronchial epithelial cells subjected to hypotonic challenge exhibited enhanced ATP release, which was paralleled by the uptake of the pannexin probe pro- pidium iodide. Both responses were reduced by pannexin 1 inhibitors and by knocking down pannexin 1. Importantly, hypotonicity-evoked ATP release from freshly excised tra- cheas and dye uptake in primary tracheal epithelial cells were impaired in pannexin 1 knockout mice. Hypotonicity-pro- moted ATP release and dye uptake in primary well differen- tiated human bronchial epithelial cells was accompanied by RhoA activation and myosin light chain phosphorylation and was reduced by the RhoA dominant negative mutant RhoA(T19N) and Rho and myosin light chain kinase inhibi- tors. ATP release and Rho activation were reduced by highly selective inhibitors of transient receptor potential vanilloid 4 (TRPV4). Lastly, knocking down TRPV4 impaired hypotonic- ity-evoked airway epithelial ATP release. Our data suggest that TRPV4 and Rho transduce cell membrane stretch/strain into pannexin 1-mediated ATP release in airway epithelia.