Regulation of caveolae through cholesterol-depletion dependent tubulation by PACSIN2/Syndapin II.

The membrane shaping ability of PACSIN2 via its F-BAR domain has been shown to be essential for caveolar morphogenesis, presumably through the shaping of the caveolar neck. Caveolar membrane contains abundant cholesterol. However, the role of cholesterol in PACSIN2-mediated membrane deformation remains unclear. We show that the binding of PACSIN2 to the membrane could be negatively regulated by cholesterol. We prepared a reconstituted membrane based on the lipid composition of caveolae. The reconstituted membrane with cholesterol had a weaker affinity to the F-BAR domain of PACSIN2 than the membrane without cholesterol. Consistently, the depletion of cholesterol from the plasma membrane induced the PACSIN2-localized tubules with caveolin-1 at their tips, suggesting that cholesterol inhibited the membrane tubulation by PACSIN2. The tubules induced by PACSIN2 were suggested to be an intermediate of caveolae endocytosis. Consistently, the removal of caveolae from the plasma membrane upon cholesterol depletion was diminished in the PACSIN2-deficient cells. These data suggested that PACSIN2 mediated caveolae internalization dependently on the amount of cholesterol, providing a mechanism for cholesterol-dependent regulation of caveolae.