title: A noninhibitory mutant of the caveolin-1 scaffolding domain enhances eNOS-derived NO synthesis and vasodilation in mice.
abstract: Aberrant regulation of eNOS and associated NO release are directly linked with various vascular diseases. Caveolin-1 (Cav-1), the main coat protein of caveolae, is highly expressed in endothelial cells. Its scaffolding domain serves as an endogenous negative regulator of eNOS function. Structure-function analysis of Cav-1 has shown that phenylalanine 92 (F92) is critical for the inhibitory actions of Cav-1 toward eNOS. Herein, we show that F92A-Cav-1 and a mutant cell-permeable scaffolding domain peptide called Cavnoxin can increase basal NO release in eNOS-expressing cells. Cavnoxin reduced vascular tone ex vivo and lowered blood pressure in normal mice. In contrast, similar experiments performed with eNOS- or Cav-1-deficient mice showed that the vasodilatory effect of Cavnoxin is abolished in the absence of these gene products, which indicates a high level of eNOS/Cav-1 specificity. Mechanistically, biochemical assays indicated that noninhibitory F92A-Cav-1 and Cavnoxin specifically disrupted the inhibitory actions of endogenous Cav-1 toward eNOS and thereby enhanced basal NO release. Collectively, these data raise the possibility of studying the inhibitory influence of Cav-1 on eNOS without interfering with the other actions of endogenous Cav-1. They also suggest a therapeutic application for regulating the eNOS/Cav-1 interaction in diseases characterized by decreased NO release.
authors.affiliation: Providence Heart and Lung Institute, St. Paul’s Hospital, James Hogg Research Centre, 1081 Burrard St., Room 166, Vancouver (BC) Canada, V6Z 1Y6. pbernatc@interchange.ubc.ca
authors.forename: Pascal
authors.initials: P
authors.lastname: Bernatchez
authors.forename: Arpeeta
authors.initials: A
authors.lastname: Sharma
authors.forename: Philip M
authors.initials: PM
authors.lastname: Bauer
authors.forename: Ethan
authors.initials: E
authors.lastname: Marin
authors.forename: William C
authors.initials: WC
authors.lastname: Sessa
mesh_terms: D000818:Animals; D051242:Caveolin 1 / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism*; D002478:Cells, Cultured; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014664:Vasodilation / Q000502:physiology*
chemical_list: D051242:Caveolin 1; D010455:Peptides; D011993:Recombinant Fusion Proteins; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III