Atg8 family LC3/GABARAP proteins are crucial for autophagosome-lysosome fusion but not autophagosome formation during PINK1/Parkin mitophagy and starvation.
Atg8 family LC3/GABARAP proteins are crucial for autophagosome-lysosome fusion but not autophagosome formation during PINK1/Parkin mitophagy and starvation.
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DOI：
10.1083/jcb.201607039
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发表时间：
2016-12-19
期刊：
影响因子：
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通讯作者：
Lazarou M
中科院分区：
文献类型：
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作者：
Nguyen TN;Padman BS;Usher J;Oorschot V;Ramm G;Lazarou M
目前的自噬模型表明 Atg8 家族 LC3/GABARAP 蛋白是自噬体生物发生的重要介质。阮等人。利用 CRISPR/Cas9 敲除 LC3 或 GABARAP 亚家族或两个亚家族，证明 Atg8 对于自噬体生物发生是可有可无的，但对于自噬体-溶酶体融合至关重要。 Atg8 蛋白家族的成员与自噬体膜缀合，被认为可以驱动自噬体形成和选择性隔离货物。在哺乳动物中，Atg8 家族由六个成员组成，分为 LC3 和 GABARAP 亚家族。为了定义 Atg8 功能，我们使用基因组编辑来敲除 HeLa 细胞中的 LC3 和 GABARAP 亚家族以及所有六个 Atg8 家族成员。我们发现 Atg8 对于自噬体形成和线粒体选择性吞噬是可有可无的，但对于自噬体-溶酶体融合至关重要。我们发现 GABARAP 亚家族促进 PLEKHM1 募集并控制自噬体-溶酶体融合，而 LC3 亚家族在这些过程中发挥的作用不太突出。尽管 GABARAP 和 LC3 都不是自噬体生物发生所必需的，但所有 Atg8 的丢失会产生更小的自噬体，并且自噬体形成的初始速率减慢。我们的结果阐明了 Atg8 家族的基本功能，并确定 GABARAP 亚家族成员是 PINK1/Parkin 线粒体自噬和饥饿自噬的主要贡献者。
Current autophagy models suggest that Atg8 family LC3/GABARAP proteins are essential mediators of autophagosome biogenesis. Nguyen et al. exploit CRISPR/Cas9-generated knockouts of the LC3 or GABARAP subfamilies, or both subfamilies, to show that Atg8s are dispensable for autophagosome biogenesis but essential for autophagosome–lysosome fusion. Members of the Atg8 family of proteins are conjugated to autophagosomal membranes, where they have been proposed to drive autophagosome formation and selective sequestration of cargo. In mammals, the Atg8 family consists of six members divided into the LC3 and GABARAP subfamilies. To define Atg8 function, we used genome editing to generate knockouts of the LC3 and GABARAP subfamilies as well as all six Atg8 family members in HeLa cells. We show that Atg8s are dispensable for autophagosome formation and selective engulfment of mitochondria, but essential for autophagosome–lysosome fusion. We find that the GABARAP subfamily promotes PLEKHM1 recruitment and governs autophagosome–lysosome fusion, whereas the LC3 subfamily plays a less prominent role in these processes. Although neither GABARAPs nor LC3s are required for autophagosome biogenesis, loss of all Atg8s yields smaller autophagosomes and a slowed initial rate of autophagosome formation. Our results clarify the essential function of the Atg8 family and identify GABARAP subfamily members as primary contributors to PINK1/Parkin mitophagy and starvation autophagy.