Breusegem Sophia Y, Seaman Matthew N J
Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
Cell Rep. 2014 Dec 11;9(5):1931-1945. doi: 10.1016/j.celrep.2014.10.053. Epub 2014 Nov 20.
Endosome-to-Golgi retrieval is an essential membrane trafficking pathway required for many important physiological processes and linked to neurodegenerative disease and infection by bacterial and viral pathogens. The prototypical cargo protein for this pathway is the cation-independent mannose 6-phosphate receptor (CIMPR), which delivers lysosomal hydrolases to endosomes. Efficient retrieval of CIMPR to the Golgi requires the retromer complex, but other aspects of the endosome-to-Golgi retrieval pathway are poorly understood. Employing an image-based antibody-uptake assay, we conducted a genome-wide RNAi loss-of-function screen for novel regulators of this trafficking pathway and report ∼90 genes that are required for endosome-to-Golgi retrieval of a CD8-CIMPR reporter protein. Among these regulators of endosome-to-Golgi retrieval are a number of multipass membrane-spanning proteins, a class of proteins often overlooked with respect to a role in membrane trafficking. We further demonstrate a role for three multipass membrane proteins, SFT2D2, ZDHHC5, and GRINA, in endosome-to-Golgi retrieval.
内体到高尔基体的回收是许多重要生理过程所需的基本膜运输途径，并且与神经退行性疾病以及细菌和病毒病原体感染有关。该途径的典型货物蛋白是阳离子非依赖性甘露糖6-磷酸受体（CIMPR），它将溶酶体水解酶输送到内体。CIMPR高效回收至高尔基体需要逆向转运复合物，但内体到高尔基体回收途径的其他方面仍知之甚少。利用基于图像的抗体摄取试验，我们对该运输途径的新型调节因子进行了全基因组RNAi功能丧失筛选，并报告了约90个基因，这些基因是CD8-CIMPR报告蛋白从内体回收至高尔基体所必需的。在内体到高尔基体回收的这些调节因子中，有许多多次跨膜蛋白，这类蛋白在膜运输中的作用常常被忽视。我们进一步证明了三种多次跨膜蛋白SFT2D2、ZDHHC5和GRINA在内体到高尔基体回收中的作用。
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