Dong Rui, Saheki Yasunori, Swarup Sharan, Lucast Louise, Harper J Wade, De Camilli Pietro
Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA; Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA; Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510, USA.
Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
Cell. 2016 Jul 14;166(2):408-423. doi: 10.1016/j.cell.2016.06.037.
VAP (VAPA and VAPB) is an evolutionarily conserved endoplasmic reticulum (ER)-anchored protein that helps generate tethers between the ER and other membranes through which lipids are exchanged across adjacent bilayers. Here, we report that by regulating PI4P levels on endosomes, VAP affects WASH-dependent actin nucleation on these organelles and the function of the retromer, a protein coat responsible for endosome-to-Golgi traffic. VAP is recruited to retromer budding sites on endosomes via an interaction with the retromer SNX2 subunit. Cells lacking VAP accumulate high levels of PI4P, actin comets, and trans-Golgi proteins on endosomes. Such defects are mimicked by downregulation of OSBP, a VAP interactor and PI4P transporter that participates in VAP-dependent ER-endosomes tethers. These results reveal a role of PI4P in retromer-/WASH-dependent budding from endosomes. Collectively, our data show how the ER can control budding dynamics and association with the cytoskeleton of another membrane by direct contacts leading to bilayer lipid modifications.
VAP（VAPA和VAPB）是一种进化上保守的内质网（ER）锚定蛋白，它有助于在内质网和其他膜之间形成连接，脂质通过这些连接在相邻双层膜之间进行交换。在此，我们报告，通过调节内体上的PI4P水平，VAP影响这些细胞器上依赖WASH的肌动蛋白成核以及retromer（一种负责内体到高尔基体运输的蛋白衣被）的功能。VAP通过与retromer的SNX2亚基相互作用被招募到内体上的retromer出芽位点。缺乏VAP的细胞在内体上积累高水平的PI4P、肌动蛋白彗星状物和反式高尔基体蛋白。这些缺陷可通过下调OSBP来模拟，OSBP是一种VAP相互作用蛋白和PI4P转运蛋白，参与依赖VAP的内质网-内体连接。这些结果揭示了PI4P在retromer/依赖WASH的内体出芽中的作用。总体而言，我们的数据表明内质网如何通过导致双层脂质修饰的直接接触来控制出芽动力学以及与另一个膜的细胞骨架的关联。
