Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.
Department of Clinical Medicine, Shanghai Tenth People's Hospital of Tongji University, Tongji University, Shanghai 200072, China.
Mol Cell. 2015 Jun 4;58(5):804-18. doi: 10.1016/j.molcel.2015.03.033. Epub 2015 Apr 30.
mTORC1 is essential for regulating cell growth and metabolism in response to various environmental stimuli. Heterodimeric Rag GTPases are required for amino-acid-mediated mTORC1 activation at the lysosome. However, the mechanism by which amino acids regulate Rag activation remains not fully understood. Here, we identified the lysosome-anchored E3 ubiquitin ligase RNF152 as an essential negative regulator of the mTORC1 pathway by targeting RagA for K63-linked ubiquitination. RNF152 interacts with and ubiquitinates RagA in an amino-acid-sensitive manner. The mutation of RagA ubiquitination sites abolishes this effect of RNF152 and enhances the RagA-mediated activation of mTORC1. Ubiquitination by RNF152 generates an anchor on RagA to recruit its inhibitor GATOR1, a GAP complex for Rag GTPases. RNF152 knockout results in the hyperactivation of mTORC1 and protects cells from amino-acid-starvation-induced autophagy. Thus, this study reveals a mechanism for regulation of mTORC1 signaling by RNF152-mediated K63-linked polyubiquitination of RagA.
mTORC1 对于响应各种环境刺激调节细胞生长和代谢是必不可少的。异二聚 Rag GTPases 对于溶酶体介导的氨基酸诱导的 mTORC1 激活是必需的。然而，氨基酸调节 Rag 激活的机制仍不完全清楚。在这里，我们通过将 RagA 靶向 K63 连接的泛素化，鉴定出溶酶体锚定的 E3 泛素连接酶 RNF152 是 mTORC1 途径的必需负调节剂。RNF152 以氨基酸敏感的方式与 RagA 相互作用并泛素化 RagA。RagA 泛素化位点的突变消除了 RNF152 的这种作用，并增强了 RagA 介导的 mTORC1 激活。RNF152 的泛素化在 RagA 上生成一个锚点，以招募其抑制剂 GATOR1，这是 Rag GTPases 的 GAP 复合物。RNF152 敲除导致 mTORC1 的过度激活，并保护细胞免受氨基酸饥饿诱导的自噬。因此，这项研究揭示了 RNF152 介导的 RagA 的 K63 连接多泛素化调节 mTORC1 信号的机制。
