siRNA-induced caveolin-1 knockdown in mice increases lung vascular permeability via the junctional pathway.
Caveolin-1, the principal integral membrane protein of caveolae, has been implicated in regulating the structural integrity of caveolae, vesicular trafficking, and signal transduction. Although the functions of caveolin-1 are beginning to be explored in caveolin-1-/- mice, these results are confounded by unknown compensatory mechanisms and the development of pulmonary hypertension, cardiomyopathy, and lung fibrosis. To address the role of caveolin-1 in regulating lung vascular permeability, in the present study we used small interfering RNA (siRNA) to knock down caveolin-1 expression in mouse lung endothelia in vivo. Intravenous injection of siRNA against caveolin-1 mRNA incorporated in liposomes selectively reduced the expression of caveolin-1 by approximately 90% within 96 h of injection compared with wild-type mice. We observed the concomitant disappearance of caveolae in lung vessel endothelia and dilated interendothelial junctions (IEJs) as well as increased lung vascular permeability to albumin via IEJs. The reduced caveolin-1 expression also resulted in increased plasma nitric oxide concentration. The nitric oxide synthase inhibitor L-NAME, in part, blocked the increased vascular albumin permeability. These morphological and functional effects of caveolin-1 knockdown were reversible within 168 h after siRNA injection, corresponding to the restoration of caveolin-1 expression. Thus our results demonstrate the essential requirement of caveolin-1 in mediating the formation of caveolae in endothelial cells in vivo and in negatively regulating IEJ permeability.
Miyawaki-Shimizu
Kayo
K
Dept. of Pharmacology, Univ. of Illinois College of Medicine, 835 So. Wolcott Ave. M/C868 Chicago, IL 60612, USA.
Predescu
Dan
D
Shimizu
Jun
J
Broman
Michael
M
Predescu
Sanda
S
Malik
Asrar B
AB
D000818:Animals; D002199:Capillary Permeability / Q000502:physiology*; D021941:Caveolae / Q000187:drug effects / Q000648:ultrastructure; D051242:Caveolin 1 / Q000096:biosynthesis* / Q000235:genetics; D008168:Lung / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000097:blood; D034741:RNA, Small Interfering
D051242:Caveolin 1; D034741:RNA, Small Interfering; D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester