ER-plasma membrane contact sites contribute to autophagosome biogenesis by regulation of local PI3P synthesis
ER-plasma membrane contact sites contribute to autophagosome biogenesis by regulation of local PI3P synthesis
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DOI：
10.15252/embj.201797006
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发表时间：
2017-07-14
期刊：
影响因子：
11.4
通讯作者：
Morel, Etienne
中科院分区：
文献类型：
--
作者：
Nascimbeni, Anna Chiara;Giordano, Francesca;Morel, Etienne
双膜结合的自噬体是由一种称为吞噬泡的结构闭合而形成的，其起源尚不清楚。由于存在 DFCP1（一种磷脂酰肌醇 3-磷酸 (PI3P) 结合蛋白）呈阳性的 omegasome 亚结构域，内质网 (ER) 显然与自噬体生物发生有关。其他膜源（例如质膜（PM））的贡献仍然难以整合到全球视野中。在这里，我们表明，通过束缚延伸突触结合蛋白（E-Syts）蛋白的直接暗示，内质网-质膜接触位点被调动用于自噬体生物发生。成像数据显示，早期自噬标记物在自噬过程中被招募到含有 E-Syt 的结构域，并且抑制 E-Syts 表达会导致自噬体生物发生的减少。此外，我们证明 E-Syts 通过招募 VMP1（PI3KC3 复合物的稳定 ER 伴侣），对于皮质 ER 膜上自噬相关的 PI3P 合成至关重要。这些结果强调了内质网质膜系链对自噬体生物发生调节的贡献，并支持膜接触位点在自噬中的重要性。
The double-membrane-bound autophagosome is formed by the closure of a structure called the phagophore, origin of which is still unclear. The endoplasmic reticulum (ER) is clearly implicated in autophagosome biogenesis due to the presence of the omegasome subdomain positive for DFCP1, a phosphatidyl-inositol-3-phosphate (PI3P) binding protein. Contribution of other membrane sources, like the plasma membrane (PM), is still difficult to integrate in a global picture. Here we show that ER-plasma membrane contact sites are mobilized for autophagosome biogenesis, by direct implication of the tethering extended synaptotagmins (E-Syts) proteins. Imaging data revealed that early autophagic markers are recruited to E-Syt-containing domains during autophagy and that inhibition of E-Syts expression leads to a reduction in autophagosome biogenesis. Furthermore, we demonstrate that E-Syts are essential for autophagy-associated PI3P synthesis at the cortical ER membrane via the recruitment of VMP1, the stabilizing ER partner of the PI3KC3 complex. These results highlight the contribution of ER-plasma membrane tethers to autophagosome biogenesis regulation and support the importance of membrane contact sites in autophagy.