title: The protective role of MLCP-mediated ERM dephosphorylation in endotoxin-induced lung injury in vitro and in vivo.
abstract: The goal of this study was to investigate the role of MLC phosphatase (MLCP) in a LPS model of acute lung injury (ALI). We demonstrate that ectopic expression of a constitutively-active (C/A) MLCP regulatory subunit (MYPT1) attenuates the ability of LPS to increase endothelial (EC) permeability. Down-regulation of MYPT1 exacerbates LPS-induced expression of ICAM1 suggesting an anti-inflammatory role of MLCP. To determine whether MLCP contributes to LPS-induced ALI in vivo, we utilized a nanoparticle DNA delivery method to specifically target lung EC. Expression of a C/A MYPT1 reduced LPS-induced lung inflammation and vascular permeability. Further, increased expression of the CS1β (MLCP catalytic subunit) also reduced LPS-induced lung inflammation, whereas the inactive CS1β mutant increased vascular leak. We next examined the role of the cytoskeletal targets of MLCP, the ERM proteins (Ezrin/Radixin/Moesin), in mediating barrier dysfunction. LPS-induced increase in EC permeability was accompanied by PKC-mediated increase in ERM phosphorylation, which was more prominent in CS1β-depleted cells. Depletion of Moesin and Ezrin, but not Radixin attenuated LPS-induced increases in permeability. Further, delivery of a Moesin phospho-null mutant into murine lung endothelium attenuated LPS-induced lung inflammation and vascular leak suggesting that MLCP opposes LPS-induced ALI by mediating the dephosphorylation of Moesin and Ezrin.
authors.affiliation: Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, Georgia.
authors.forename: Anita
authors.initials: A
authors.lastname: Kovacs-Kasa
authors.affiliation: Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, Georgia.
authors.forename: Boris A
authors.initials: BA
authors.lastname: Gorshkov
authors.affiliation: Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, Georgia.
authors.forename: Kyung-Mi
authors.initials: KM
authors.lastname: Kim
authors.affiliation: Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, Georgia.
authors.forename: Sanjiv
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Center for Lung Vascular Pathobiology, University of Arizona, Phoenix, Arizona.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Black
authors.affiliation: Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, Georgia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Fulton
authors.affiliation: Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia.
authors.forename: Christiana
authors.initials: C
authors.lastname: Dimitropoulou
authors.affiliation: Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia.
authors.forename: John D
authors.initials: JD
authors.lastname: Catravas
authors.affiliation: Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, Georgia.
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Verin
mesh_terms: D055371:Acute Lung Injury / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008070:Lipopolysaccharides / Q000633:toxicity*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism*; D043263:Myosin-Light-Chain Phosphatase / Q000378:metabolism*; D010766:Phosphorylation; D000099149:Ezrin
chemical_list: D003598:Cytoskeletal Proteins; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D008840:Microfilament Proteins; D043263:Myosin-Light-Chain Phosphatase; D000099149:Ezrin; C071058:moesin; C071776:radixin; C510645:Ppp1r12a protein, mouse