Distinction between signaling mechanisms in lipid rafts vs. caveolae.
The relative importance of lipid rafts vs. specialized rafts termed caveolae to influence signal transduction is not known. Here we show that in cells lacking caveolae, the dually acylated protein, endothelial nitric oxide synthase (eNOS), localizes to cholesterol-rich lipid raft domains of the plasma membrane. In these cells, expression of caveolin-1 (cav-1) stimulates caveolae biogenesis, promotes the interaction of cav-1 with eNOS, and the inhibition of NO release from cells. Interestingly, in cells where cav-1 does not drive caveolae assembly, despite equal levels of cav-1 and eNOS and localization of both proteins to raft domains of the plasmalemma, the physical interaction of eNOS with cav-1 is dramatically less resulting in less inhibition of NO release. Thus, cav-1 concentrated in caveolae, not in rafts, is in closer proximity to eNOS and is necessary for negative regulation of eNOS function, thereby providing the first clear example of spatial regulation of signaling in this organelle that is distinct from raft domains.
Sowa
G
G
Department of Pharmacology, Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA.
Pypaert
M
M
Sessa
W C
WC
D000818:Animals; D021941:Caveolae / Q000378:metabolism*; D051242:Caveolin 1; D022461:Caveolins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D052250:Nitric Oxide Synthase Type III; D051381:Rats; D011916:Rats, Inbred F344; D015398:Signal Transduction / Q000502:physiology*; D013961:Thyroid Gland / Q000166:cytology
C495540:CAV1 protein, human; C495537:Cav1 protein, rat; D051242:Caveolin 1; D022461:Caveolins; D009569:Nitric Oxide; D002784:Cholesterol; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat