The Henry Wellcome Integrated Signalling Laboratories, School of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, England, UK.
J Cell Biol. 2012 Apr 16;197(2):219-30. doi: 10.1083/jcb.201111121. Epub 2012 Apr 9.
The FERM-like domain-containing sorting nexins of the SNX17/SNX27/SNX31 family have been proposed to mediate retrieval of transmembrane proteins from the lysosomal pathway. In this paper, we describe a stable isotope labeling with amino acids in culture-based quantitative proteomic approach that allows an unbiased, global identification of transmembrane cargoes that are rescued from lysosomal degradation by SNX17. This screen revealed that several integrins required SNX17 for their stability, as depletion of SNX17 led to a loss of β1 and β5 integrins and associated a subunits from HeLa cells as a result of increased lysosomal degradation. SNX17 bound to the membrane distal NPXY motif in β integrin cytoplasmic tails, thereby preventing lysosomal degradation of β integrins and their associated a subunits. Furthermore, SNX17-dependent retrieval of integrins did not depend on the retromer complex. Consistent with an effect on integrin recycling, depletion of SNX17 also caused alterations in cell migration. Our data provide mechanistic insight into the retrieval of internalized integrins from the lysosomal degradation pathway, a prerequisite for subsequent recycling of these matrix receptors.
FERM 样结构域富含分选连接蛋白家族的 SNX17/SNX27/SNX31 家族被提出介导从溶酶体途径中回收跨膜蛋白。在本文中，我们描述了一种基于稳定同位素标记与氨基酸培养的定量蛋白质组学方法，该方法可以无偏地、全局地鉴定出被 SNX17 从溶酶体降解中拯救出来的跨膜货物。该筛选揭示了几种整合素需要 SNX17 才能稳定存在，因为 SNX17 的耗竭导致 HeLa 细胞中β1 和β5 整合素及其相关的 a 亚基由于溶酶体降解增加而丢失。SNX17 与β整合素胞质尾部的膜远端 NPXY 基序结合，从而防止β整合素及其相关 a 亚基的溶酶体降解。此外，SNX17 依赖性整合素的回收不依赖于逆行体复合物。与整合素回收的影响一致，SNX17 的耗竭也导致细胞迁移发生改变。我们的数据为从溶酶体降解途径中回收内化的整合素提供了机制上的见解，这是这些基质受体随后进行循环所必需的。
