Characterization of autophagosome formation site by a hierarchical analysis of mammalian Atg proteins
Characterization of autophagosome formation site by a hierarchical analysis of mammalian Atg proteins
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DOI：
10.4161/auto.6.6.12709
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发表时间：
2010-08-16
期刊：
影响因子：
13.3
通讯作者：
Mizushima, Noboru
中科院分区：
文献类型：
--
作者：
Itakura, Eisuke;Mizushima, Noboru
自噬是一种细胞内降解过程，通过该过程，胞质物质被递送至溶酶体。尽管最近鉴定了许多自噬相关基因，但自噬体是如何产生的仍不清楚。在这里，我们检查了哺乳动物 Atg 蛋白之间的层次关系。在饥饿条件下，ULK1、Atg14、WIPI-1、LC3 和 Atg16L1 靶向同一区室，而 DFCP1 定位于这些 Atg 蛋白附近。就斑点形成而言，包括 ULK1 和 FIP200 的蛋白质复合物是最上游单元，是含有 Atg14 的 PI3-激酶复合物的斑点形成所必需的。 DFCP1 和 WIPI-1 的斑点形成都需要 FIP200 和 Atg14。 Atg12-Atg5-Atg16L1 复合体和 LC3 是这些因子中的下游单元。含有上游 Atg 蛋白（如 ULK1 和 Atg14）的点状结构与 ER 紧密结合，ER 蛋白液泡膜蛋白 1 (VMP1) 也短暂定位于其中。即使用渥曼青霉素处理细胞以抑制自噬体形成，这些结构也会形成。这些层次分析表明 ULK1、Atg14 和 VMP1 以与 PI3 激酶活性无关的方式定位于 ER 相关自噬体形成位点。
Autophagy is an intracellular degradation process, through which cytosolic materials are delivered to the lysosome. Despite recent identification of many autophagy-related genes, how autophagosomes are generated remains unclear. Here, we examined the hierarchical relationships among mammalian Atg proteins. Under starvation conditions, ULK1, Atg14, WIPI-1, LC3 and Atg16L1 target to the same compartment, whereas DFCP1 localizes adjacently to these Atg proteins. In terms of puncta formation, the protein complex including ULK1 and FIP200 is the most upstream unit and is required for puncta formation of the Atg14-containing PI3-kinase complex. Puncta formation of both DFCP1 and WIPI-1 requires FIP200 and Atg14. The Atg12-Atg5-Atg16L1 complex and LC3 are downstream units among these factors. The punctate structures containing upstream Atg proteins such as ULK1 and Atg14 tightly associate with the ER, where the ER protein vacuole membrane protein 1 (VMP1) also transiently localizes. These structures are formed even when cells are treated with wortmannin to suppress autophagosome formation. These hierarchical analyses suggest that ULK1, Atg14 and VMP1 localize to the ER-associated autophagosome formation sites in a PI3-kinase activity-independent manner.