TY - JOUR T1 - Focal adhesions control stretch-induced rho signaling and vascular permeability via paxillin – GEF-H1 functional complex JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - P3923 AU - Konstantin Birukov AU - Grzegorz Gawlak AU - Yufeng Tian Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/P3923.abstract N2 - Suboptimal ventilator support or regional ventilation heterogeneity in inflamed lungs causes excessive tissue distension which triggers stretch-induced pathologic signaling and may lead to vascular leak and lung dysfunction. Focal adhesions (FA) are cell-substrate adhesive complexes participating in cellular mechanotransduction and regulation of the Rho GTPase pathway. Stretch-induced Rho regulation remains poorly understood. We used human lung endothelial cells (EC) exposed to pathologic cyclic stretch (CS) at 18% distension to test the hypothesis that FA protein paxillin participates in CS-induced Rho activation by recruiting the Rho-specific guanine nucleotide exchange factor GEF-H1. CS induced phosphorylation of paxillin, activated p42/44-MAP kinase, Rho GTPase, paxillin/GEF-H1/p42/44-MAPK association. CS caused nearly 2-fold increase in EC permeability, which was attenuated by paxillin knockdown. Expression of paxillin-Y31/118F phosphorylation mutant decreased the CS-induced paxillin/GEF-H1 association (16.3+/-4.1%), GEF-H1 activation (28.9+/-9.2%), and EC permeability (28.7+/-8.1%), but not CS-induced p42/44-MAPK activation. Inhibition of p42/44-MAPK suppressed CS-induced paxillin/GEF-H1 interactions (15.9+/-7.9%), GEF-H1 activation (11.7+/-4.3%) and disruption of EC monolayer. Expression of GEF-H1T678A lacking p42/44-MAPK phosphorylation site attenuated Rho activation (31.2+/-11.6%). We conclude that MAPK-dependent targeting of GEF-H1 to paxillin is involved in the regulation of CS-induced Rho signaling and EC permeability. This study proposes a novel concept of paxillin-GEF-H1-p42/44-MAPK module as a regulator of pathologic mechanotransduction. ER -