C9orf72 associates with inactive Rag GTPases and regulates mTORC1-mediated autophagosomal and lysosomal biogenesis.
C9orf72 associates with inactive Rag GTPases and regulates mTORC1-mediated autophagosomal and lysosomal biogenesis.
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C9orf72 与失活的 Rag GTPases 相关并调节 mTORC1 介导的自噬体和溶酶体生物发生。
DOI：
10.1111/acel.13126
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发表时间：
2020
期刊：
影响因子：
7.8
通讯作者：
Ying Zheng
中科院分区：
文献类型：
--
作者：
Wang Mingmei;Wang Hongfeng;Tao Zhouteng;Xia Qin;Hao Zongbing;Prehn Jochen H M;Zhen Xuechu;Wang Guanghui;Ying Zheng
C9 orf 72中GGGGCC重复扩增是额颞叶痴呆（FTD）和肌萎缩侧索硬化（ALS）这两种与衰老相关的神经退行性疾病中最常见的遗传原因。C9 orf 72非编码区的双向重复扩增已被证明通过重复相关的非ATG（RAN）翻译产生二肽重复（DPR）蛋白，并降低C9 orf 72基因产物C9 orf 72蛋白的表达水平。C9 orf 72连锁神经退行性变的机制包括RNA重复序列功能增加、DPR毒性和C9 orf 72蛋白功能丧失。本论文主要研究C9 orf 72蛋白的细胞功能。我们报道C9 orf 72可以在转录水平上调节溶酶体的生物合成和自噬。我们发现，C9 orf 72的丢失导致细胞中溶酶体、自噬体和自溶酶体的显著积累，这与mTORC 1活性抑制和MiT/TFE家族成员MITF、TFE 3和TFEB（溶酶体生物发生和自噬的三个主要调节因子）的核转位增强有关。我们证明了C9 orf 72的DENN结构域特异性结合非活性Rag GTP酶，但不结合活性Rag GTP酶，从而影响Rag/raptor/mTOR复合物的功能和mTORC 1活性。此外，活性Rag GTP酶，而不是非活性Rag GTP酶或raptor，挽救了C9 orf 72缺陷细胞中mTORC 1受损的活性和溶酶体定位。总之，本研究强调了C9 orf 72在溶酶体和自噬体调节中的关键作用，并证明了Rag GTP酶和mTORC 1参与了C9 orf 72介导的自噬。
GGGGCC repeat expansion inC9orf72is the most common genetic cause in both frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), two neurodegenerative disorders in association with aging. Bidirectional repeat expansions in the noncoding region ofC9orf72have been shown to produce dipeptide repeat (DPR) proteins through repeat‐associated non‐ATG (RAN) translation and to reduce the expression level of theC9orf72gene product, C9orf72 protein. Mechanisms underlyingC9orf72‐linked neurodegeneration include expanded RNA repeat gain of function, DPR toxicity, and C9orf72 protein loss of function. In the current study, we focus on the cellular function of C9orf72 protein. We report that C9orf72 can regulate lysosomal biogenesis and autophagy at the transcriptional level. We show that loss of C9orf72 leads to striking accumulation of lysosomes, autophagosomes, and autolysosomes in cells, which is associated with suppressed mTORC1 activity and enhanced nuclear translocation of MiT/TFE family members MITF, TFE3, and TFEB, three master regulators of lysosomal biogenesis and autophagy. We demonstrate that the DENN domain of C9orf72 specifically binds to inactive Rag GTPases, but not active Rag GTPases, thereby affecting the function of Rag/raptor/mTOR complex and mTORC1 activity. Furthermore, active Rag GTPases, but not inactive Rag GTPases or raptor rescued the impaired activity and lysosomal localization of mTORC1 in C9orf72‐deficient cells. Taken together, the present study highlights a key role of C9orf72 in lysosomal and autophagosomal regulation, and demonstrates that Rag GTPases and mTORC1 are involved in C9orf72‐mediated autophagy.