mTOR-mediated phosphorylation of VAMP8 and SCFD1 regulates autophagosome maturation.
mTOR-mediated phosphorylation of VAMP8 and SCFD1 regulates autophagosome maturation.
复制标题
mTOR 介导的 VAMP8 和 SCFD1 磷酸化调节自噬体成熟。
DOI：
10.1038/s41467-021-26824-5
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发表时间：
2021-11-16
影响因子：
16.6
通讯作者：
Liu R
中科院分区：
文献类型：
--
作者：
Huang H;Ouyang Q;Zhu M;Yu H;Mei K;Liu R
哺乳动物雷帕霉素靶蛋白（mTORC 1）已被证明在不同的步骤调节自噬。然而，mTORC 1如何调节N-乙基马来酰亚胺敏感蛋白受体（SNARE）复合物仍然难以捉摸。在这里，我们发现mTORC 1通过磷酸化VAMP 8抑制SNARE复合物（STX 17-SNAP 29-VAMP 8）的形成，从而阻断自噬体-溶酶体融合。VAMP 8磷酸化模拟突变体不能促进体外自噬体-溶酶体融合。此外，我们还鉴定了SCFD 1，一种Sec 1/Munc 18样蛋白，定位于自体溶酶体，是SNARE复合物形成和自噬体-溶酶体融合所必需的。VAMP 8在去磷酸化时促进SCFD 1向自体溶酶体的募集。一致地，磷酸化的VAMP 8或SCFD 1消耗抑制自噬体-溶酶体融合，并且当在小鼠肝脏中表达时，磷酸模拟VAMP 8的表达导致增加的脂滴积累。因此，我们的研究支持mTORC 1介导的VAMP 8磷酸化阻断SCFD 1募集，从而抑制STX 17-SNAP 29-VAMP 8复合物形成和自噬体-溶酶体融合。自噬依赖于细胞器膜的协调融合，尽管调节机制之间的相互作用还没有得到很好的研究。在这里，作者表明SNARE复合物的形成受到VAMP 8的mTORC 1磷酸化的抑制，这阻止了自噬体-溶酶体融合。
The mammalian target of rapamycin (mTORC1) has been shown to regulate autophagy at different steps. However, how mTORC1 regulates the N-ethylmaleimide-sensitive protein receptor (SNARE) complex remains elusive. Here we show that mTORC1 inhibits formation of the SNARE complex (STX17-SNAP29-VAMP8) by phosphorylating VAMP8, thereby blocking autophagosome-lysosome fusion. A VAMP8 phosphorylation mimic mutant is unable to promote autophagosome-lysosome fusion in vitro. Furthermore, we identify SCFD1, a Sec1/Munc18-like protein, that localizes to the autolysosome and is required for SNARE complex formation and autophagosome-lysosome fusion. VAMP8 promotes SCFD1 recruitment to autolysosomes when dephosphorylated. Consistently, phosphorylated VAMP8 or SCFD1 depletion inhibits autophagosome-lysosome fusion, and expression of phosphomimic VAMP8 leads to increased lipid droplet accumulation when expressed in mouse liver. Thus, our study supports that mTORC1-mediated phosphorylation of VAMP8 blocks SCFD1 recruitment, thereby inhibiting STX17-SNAP29-VAMP8 complex formation and autophagosome-lysosome fusion. Autophagy relies on coordinated fusion of organelle membranes, although the interplay between the regulatory machinery is not well studied. Here, the authors show that SNARE complex formation is inhibited by mTORC1 phosphorylation of VAMP8, which prevents autophagosome-lysosome fusion.