title: Inhibition of endothelial barrier dysfunction by P21-activated kinase-1.
abstract: We investigated the activity of P21-activated kinase-1 (Pak1) on myosin light chain phosphorylation and on thrombin-induced barrier dysfunction in human endothelial cells (HMEC). HMEC were infected with recombinant adenoviruses that express constitutively active Pak1, LacZ, wild-type, and a mutant myosin regulatory light chain, mMLC20 (Thr18Ala, Ser19Ala). Expression of the recombinant Pak1 mediated by adenovirus in HMEC was regulated. Active Pak1 induced dephosphorylation of MLC20 in HMEC, but not in smooth muscle cells. Active Pak1 significantly inhibited thrombin-induced endothelial barrier dysfunction. Expression of the unphosphorylatable MLC20 also inhibited thrombin-induced endothelial barrier dysfunction. Constitutively active Pak1 associated with phosphatase 2A and induced a post-translational modification of the phosphatase. Our data provide novel evidence indicating that Pak1 regulates endothelial barrier function through activation of phosphatase 2A.
authors.affiliation: Department of Physiology and Biophysics M/C 901 and Center for Cardiovascular Research, University of Illinois at Chicago, 835 South Wolcott Avenue, Chicago, IL 60612, USA. yke@uic.edu
authors.forename: Yunbo
authors.initials: Y
authors.lastname: Ke
authors.forename: Hazel
authors.initials: H
authors.lastname: Lum
authors.forename: R John
authors.initials: RJ
authors.lastname: Solaro
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D042783:Endothelial Cells / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D054648:Protein Phosphatase 2; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011651:Pulmonary Artery / Q000166:cytology; D051381:Rats; D013552:Swine; D013917:Thrombin / Q000494:pharmacology; D054462:p21-Activated Kinases
chemical_list: D018994:Myosin Light Chains; C515903:PAK1 protein, human; C515911:PAK3 protein, human; C515906:Pak1 protein, rat; C515913:Pak3 protein, rat; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D013917:Thrombin