CAVEOLIN-1 DETERGENT SOLUBILITY AND ASSOCIATION WITH ENDOTHELIAL NITRIC-OXIDE SYNTHASE IS MODULATED BY TYROSINE PHOSPHORYLATION

Caveolin-1 and endothelial nitric oxide synthase (eNOS) are associated within endothelial caveolae. We have shown previously that eNOS is tr anslocated to the detergent-insoluble, cytoskeletal fraction of bovine aortic endothelial cells (BAEC) in response to bradykinin (BK)-stimul ation or tyrosine phosphatase inhibition. In the present study, we hav e examined whether caveolin-1 is similarly translocated in response to these or other stimuli. Exposure of BAEC to the eNOS-activating agoni sts, BK, histamine, or ATP produces transient increases in the amounts of detergent-insoluble caveolin-1. Increases in insolubility are bloc ked by tyrosine kinase inhibitors and are potently mimicked by tyrosin e phosphatase inhibitors. Increased insolubility is accompanied by an increased association of caveolin-1 with eNOS and inhibition of eNOS c atalytic activity. Agonist-activation of eNOS in endothelial cells thu s appears to involve tyrosine phosphorylation-dependent changes in the interaction of eNOS with caveolin-1. Increased interaction of eNOS wi th caveolin-1 may deactivate the enzyme subsequent to its activation b y Ca2+/calmodulin. (C) 1997 Academic Press.