Inhibition of volume-regulated anion channels by dominant-negative caveolin-1

Caveolae are flask-shaped invaginations of the plasma membrane formed by th e association of caveolin proteins with lipid rafts. In endothelial cells, caveolae function as signal transduction centers controlling NO synthesis a nd mechanotransduction. We now provide evidence that the endothelial volume -regulated anion channel (VRAC) is also under the control of the caveolar s ystem. When calf pulmonary artery endothelial (CPAE) cells were transfected with caveolin-1 Delta1-81 (deletion of amino acids 1 to 81), activation of VRAC by hypotonic cell swelling was strongly impaired. Concomitantly, cave olin-1 Delta1-81 disturbed the formation of caveolin-1 containing lipid raf ts as evidenced by sucrose density gradient centrifugation. In nontransfect ed cells, endogenous caveolin-1 typically associated with low-density, dete rgent-resistant lipid rafts. However, transient expression of caveolin-1 De lta1-81 caused a redistribution of endogenous caveolin-1 to high-density, d etergent-soluble membrane fractions. We therefore conclude that the interac tion between caveolin-1 and detergent-resistant lipid rafts is an important prerequisite for endothelial VRAC activity. (C) 2001 Academic Press.