The membrane-shaping ability of PACSIN2 (also known as syndapin II), which is mediated by its F-BAR domain, has been shown to be essential for caveolar morphogenesis, presumably through the shaping of the caveolar neck. Caveolar membranes contain abundant cholesterol. However, the role of cholesterol in PACSIN2-mediated membrane deformation remains unclear. Here, we show that the binding of PACSIN2 to the membrane can be negatively regulated by cholesterol. We prepared reconstituted membranes based on the lipid composition of caveolae. The reconstituted membrane with cholesterol had a weaker affinity for the F-BAR domain of PACSIN2 than a membrane without cholesterol. Consistent with this, upon depletion of cholesterol from the plasma membrane, PACSIN2 localized at tubules that had caveolin-1 at their tips, suggesting that cholesterol inhibits membrane tubulation mediated by PACSIN2. The tubules induced by PACSIN2 could be representative of an intermediate of caveolae endocytosis. Consistent with this, the removal of caveolae from the plasma membrane upon cholesterol depletion was diminished in the PACSIN2-deficient cells. These data suggest that PACSIN2-mediated caveolae internalization is dependent on the amount of cholesterol, providing a mechanism for cholesterol-dependent regulation of caveolae.

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PACSIN2（也称为 Syndapin II）的膜成形能力由其 F-BAR 结构域介导，已被证明对于小凹形态发生至关重要，推测可能是通过小凹颈的成形来实现的。小凹膜含有丰富的胆固醇。然而，胆固醇在 PACSIN2 介导的膜变形中的作用仍不清楚。在这里，我们证明 PACSIN2 与膜的结合可以受到胆固醇的负向调节。我们根据小凹的脂质成分制备了重构膜。与不含胆固醇的膜相比，含有胆固醇的重构膜对 PACSIN2 的 F-BAR 结构域的亲和力更弱。与此一致的是，当质膜上的胆固醇耗尽时，PACSIN2 定位于尖端具有 Caveolin-1 的小管，表明胆固醇抑制 PACSIN2 介导的膜管状作用。PACSIN2 诱导的小管可以代表小窝内吞作用的中间体。与此一致的是，在 PACSIN2 缺陷细胞中，胆固醇耗尽后，细胞质膜上的小凹的去除减少了。这些数据表明 PACSIN2 介导的小窝内化依赖于胆固醇的量，为胆固醇依赖性小窝调节提供了机制。

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