title: Novel mechanism of endothelial nitric oxide synthase activation mediated by caveolae internalization in endothelial cells.
abstract: Caveolin-1, the caveolae scaffolding protein, binds to and negatively regulates eNOS activity. As caveolin-1 also regulates caveolae-mediated endocytosis after activation of the 60-kDa albumin-binding glycoprotein gp60 in endothelial cells, we addressed the possibility that endothelial NO synthase (eNOS)-dependent NO production was functionally coupled to caveolae internalization. We observed that gp60-induced activation of endocytosis increased NO production within 2 minutes and up to 20 minutes. NOS inhibitor N(G)-nitro-L-arginine (L-NNA) prevented the NO production. To determine the role of caveolae internalization in the mechanism of NO production, we expressed dominant-negative dynamin-2 mutant (K44A) or treated cells with methyl-beta-cyclodextrin. Both interventions inhibited caveolae-mediated endocytosis and NO generation induced by gp60. We determined the role of signaling via Src kinase in the observed coupling of endocytosis to eNOS activation. Src activation induced the phosphorylation of caveolin-1, Akt and eNOS, and promoted dissociation of eNOS from caveolin-1. Inhibitors of Src kinase and Akt also prevented NO production. In isolated perfused mouse lungs, gp60 activation induced NO-dependent vasodilation, whereas the response was attenuated in eNOS(-/-) or caveolin-1(-/-) lungs. Together, these results demonstrate a critical role of caveolae-mediated endocytosis in regulating eNOS activation in endothelial cells and thereby the NO-dependent vasomotor tone.
authors.affiliation: University of Illinois College of Medicine, Department of Pharmacology, 835 S Wolcott Ave, Chicago, IL 60612, USA.
authors.forename: Nikolaos A
authors.initials: NA
authors.lastname: Maniatis
authors.forename: Viktor
authors.initials: V
authors.lastname: Brovkovych
authors.forename: Scott E
authors.initials: SE
authors.lastname: Allen
authors.forename: Theresa A
authors.initials: TA
authors.lastname: John
authors.forename: Ayesha N
authors.initials: AN
authors.lastname: Shajahan
authors.forename: Chinnaswamy
authors.initials: C
authors.lastname: Tiruppathi
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Vogel
authors.forename: Randal A
authors.initials: RA
authors.lastname: Skidgel
authors.forename: Asrar B
authors.initials: AB
authors.lastname: Malik
authors.forename: Richard D
authors.initials: RD
authors.lastname: Minshall
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology; D021941:Caveolae / Q000502:physiology*; D051242:Caveolin 1 / Q000172:deficiency / Q000378:metabolism; D002478:Cells, Cultured; D004705:Endocytosis / Q000502:physiology*; D042783:Endothelial Cells / Q000201:enzymology* / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D044387:GTP-Binding Protein beta Subunits / Q000502:physiology; D044388:GTP-Binding Protein gamma Subunits / Q000502:physiology; D008168:Lung / Q000098:blood supply; D051379:Mice; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000096:biosynthesis; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D051381:Rats; D012795:Sialoglycoproteins / Q000502:physiology; D013997:Time Factors; D014018:Tissue Distribution; D014664:Vasodilation; D019061:src-Family Kinases / Q000502:physiology
chemical_list: D051242:Caveolin 1; C118981:G-protein Beta gamma; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D012795:Sialoglycoproteins; C065610:sialoglycoprotein gp60; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt; D002118:Calcium