Induction of vascular permeability: beta PIX and GIT1 scaffold the activation of extracellular signal-regulated kinase by PAK.
Increased permeability of blood vessels is an important component of inflammation, but in some circumstances it contributes to tissue injury and organ failure. Previous work showed that p21-activated kinase (PAK) is a critical regulator of endothelial cell-cell junctions through effects on myosin light chain phosphorylation and cell contractility. We now show that blocking PAK function inhibits fluid leak in a mouse model of acute lung injury. In cultured endothelial cells, induction of myosin light chain phosphorylation by PAK is mediated by mitogen-activated protein kinase kinase and extracellular signal-regulated kinase (Erk). Erk in lipopolysaccharide (LPS)-treated mouse lung is activated in a PAK-dependent manner in several cell types, most prominently vascular endothelium. Activation of Erk requires the integrity of the complex between PAK, PIX, and GIT1. Several means of disrupting this complex inhibit stimulation of vascular permeability in vitro. A cell-permeant peptide that blocks binding of PAK to PIX inhibits LPS-induced fluid leak in the mouse lung injury model. We conclude that the PAK-PIX-GIT1 complex is critical for Erk-dependent myosin phosphorylation and vascular permeability.
Stockton
Rebecca
R
Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA.
Reutershan
Jörg
J
Scott
David
D
Sanders
John
J
Ley
Klaus
K
Schwartz
Martin Alexander
MA
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002199:Capillary Permeability; D002417:Cattle; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology; D008168:Lung / Q000378:metabolism / Q000473:pathology; D051379:Mice; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D064067:Rho Guanine Nucleotide Exchange Factors; D054462:p21-Activated Kinases
C576606:ARHGEF7 protein, human; D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; C485647:GIT1 protein, human; D020662:Guanine Nucleotide Exchange Factors; D008070:Lipopolysaccharides; D010455:Peptides; D064067:Rho Guanine Nucleotide Exchange Factors; C515903:PAK1 protein, human; C515905:Pak1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D048049:Extracellular Signal-Regulated MAP Kinases