Kim Ji Hyun, Singh Ashutosh, Del Poeta Maurizio, Brown Deborah A, London Erwin
Dept. of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA.
Dept. of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794, USA.
J Cell Sci. 2017 Aug 15;130(16):2682-2695. doi: 10.1242/jcs.201731. Epub 2017 Jun 27.
Ordered lipid domains (rafts) in plasma membranes have been hypothesized to participate in endocytosis based on inhibition of endocytosis by removal or sequestration of cholesterol. To more carefully investigate the role of the sterol in endocytosis, we used a substitution strategy to replace cholesterol with sterols that show various raft-forming abilities and chemical structures. Both clathrin-mediated endocytosis of transferrin and clathrin-independent endocytosis of clustered placental alkaline phosphatase were measured. A subset of sterols reversibly inhibited both clathrin-dependent and clathrin-independent endocytosis. The ability of a sterol to support lipid raft formation was necessary for endocytosis. However, it was not sufficient, because a sterol lacking a 3β-OH group did not support endocytosis even though it had the ability to support ordered domain formation. Double bonds in the sterol rings and an aliphatic tail structure identical to that of cholesterol were neither necessary nor sufficient to support endocytosis. This study shows that substitution using a large number of sterols can define the role of sterol structure in cellular functions. Hypotheses for how sterol structure can similarly alter clathrin-dependent and clathrin-independent endocytosis are discussed.
基于通过去除或隔离胆固醇来抑制内吞作用，细胞膜中的有序脂质结构域（脂筏）被推测参与内吞作用。为了更仔细地研究固醇在内吞作用中的作用，我们采用了一种替代策略，用具有不同脂筏形成能力和化学结构的固醇取代胆固醇。我们同时检测了网格蛋白介导的转铁蛋白内吞作用和网格蛋白非依赖性的聚集胎盘碱性磷酸酶内吞作用。一部分固醇可逆地抑制了网格蛋白依赖性和网格蛋白非依赖性内吞作用。固醇支持脂质筏形成的能力对于内吞作用是必要的。然而，这并不充分，因为缺乏3β-OH基团的固醇即使具有支持有序结构域形成的能力，也不支持内吞作用。固醇环中的双键和与胆固醇相同的脂肪族尾部结构对于支持内吞作用既非必要也不充分。这项研究表明，使用大量固醇进行替代可以确定固醇结构在细胞功能中的作用。我们还讨论了固醇结构如何类似地改变网格蛋白依赖性和网格蛋白非依赖性内吞作用的假说。
