title: Asef controls vascular endothelial permeability and barrier recovery in the lung.
abstract: Increased levels of hepatocyte growth factor (HGF) in injured lungs may reflect a compensatory response to diminish acute lung injury (ALI). HGF-induced activation of Rac1 GTPase stimulates endothelial barrier protective mechanisms. This study tested the involvement of Rac-specific guanine nucleotide exchange factor Asef in HGF-induced endothelial cell (EC) cytoskeletal dynamics and barrier protection in vitro and in a two-hit model of ALI. HGF induced membrane translocation of Asef and stimulated Asef Rac1-specific nucleotide exchange activity. Expression of constitutively activated Asef mutant mimicked HGF-induced peripheral actin cytoskeleton enhancement. In contrast, siRNA-induced Asef knockdown or expression of dominant-negative Asef attenuated HGF-induced Rac1 activation evaluated by Rac-GTP pull down and FRET assay with Rac1 biosensor. Molecular inhibition of Asef attenuated HGF-induced peripheral accumulation of cortactin, formation of lamellipodia-like structures, and enhancement of VE-cadherin adherens junctions and compromised HGF-protective effect against thrombin-induced RhoA GTPase activation, Rho-dependent cytoskeleton remodeling, and EC permeability. Intravenous HGF injection attenuated lung inflammation and vascular leak in the two-hit model of ALI induced by excessive mechanical ventilation and thrombin signaling peptide TRAP6. This effect was lost in Asef(-/-) mice. This study shows for the first time the role of Asef in HGF-mediated protection against endothelial hyperpermeability and lung injury.
authors.affiliation: Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637.
authors.forename: Xinyong
authors.initials: X
authors.lastname: Tian
authors.affiliation: Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Gawlak
authors.affiliation: Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637.
authors.forename: Fanyong
authors.initials: F
authors.lastname: Meng
authors.affiliation: Laboratory of Molecular and Genetic Information, Institute for Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kawasaki
authors.affiliation: Laboratory of Molecular and Genetic Information, Institute for Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan.
authors.forename: Tetsu
authors.initials: T
authors.lastname: Akiyama
authors.affiliation: Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637 abirukov@medicine.bsd.uchicago.edu.
authors.forename: Anna A
authors.initials: AA
authors.lastname: Birukova
mesh_terms: D000818:Animals; D002463:Cell Membrane Permeability; D055785:Gene Knockdown Techniques; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017228:Hepatocyte Growth Factor / Q000494:pharmacology; D008168:Lung / Q000378:metabolism*; D051379:Mice; D034622:RNA Interference; D064067:Rho Guanine Nucleotide Exchange Factors; D015398:Signal Transduction; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: C547838:Arhgef4 protein, mouse; D020662:Guanine Nucleotide Exchange Factors; D064067:Rho Guanine Nucleotide Exchange Factors; D017228:Hepatocyte Growth Factor; D020830:rac1 GTP-Binding Protein