The diverse roles of ER-Golgi trafficking machinery in autophagy and ER quality control

项目摘要 这项建议中的研究旨在了解分泌机制在两种不同的 使用自噬小体的自噬途径的类型、批量自噬和选择性自噬 内质网(ER)。自噬缺陷与癌症和多种人类疾病有关 疾病，包括神经退行性疾病。自噬是一种保守的分解代谢过程，它以 用于降解的细胞成分。当自噬被诱导时，膜结合成吞噬成分。 以降级为目标。一旦这些膜密封形成自噬小体，它们的内容物就会被输送 到溶酶体或液泡中进行降解。我的实验室已经证明了Rab GTP酶Ypt1的重要性 (哺乳动物中的Rab1)在启动这些事件中。 当细胞缺乏营养时，大量的自噬被上调，以迅速制造更多的营养。这个 饥饿期间对膜的高需求以制造更多的自噬小体导致戏剧性的 细胞内膜的重组。我们已经证明，分泌途径在 饥饿和来自分泌途径的膜被重定向到大量自噬途径。 此外，我们发现，分泌机械的磷酸化在重新编程中起着关键作用 用于批量自噬的膜。我们研究的未来目标是确定触发保守的 酵母(酿酒酵母)在饥饿过程中发生的膜重排事件 哺乳动物细胞。我们还将讨论自噬体膜与 来自早期分泌途径的膜。 选择性自噬途径使用货物受体来降解有毒聚集体和受损的 细胞器亚域。这些受体将目标为降解的货物与自噬联系起来。 机械设备。我们对自噬的研究现在已经扩展到包括内质网的选择性降解，也 叫做ER-食人症。了解内质网吞噬具有治疗重要性，因为这一途径似乎 对于清除来自急诊室的有毒聚集体是必不可少的。内质网吞噬功能是如何针对受损区域的 ER降级并将这些域与网络的其余部分分开仍不得而知。我们发起了一项 在酵母中进行遗传筛选，并已确定在内质网吞噬中起作用的关键保守因素。其中一些因素 是早期分泌途径的组成部分，也与Atg40一起工作。Atg40是一个保守的 参与将ER亚域包装成自噬小体的Cargo受体。目标是 我们的研究是为了了解Atg40如何与这些新发现的保守成分一起作用于靶向和 在酵母和哺乳动物细胞中ER吞噬过程中，ER亚区被切断。

Project Summary The studies in this proposal are aimed at understanding the role of secretory machinery on two different types of autophagy pathways that use autophagosomes, bulk autophagy and the selective autophagy of the endoplasmic reticulum (ER). Defects in autophagy have been linked to cancer and a variety of human diseases, including neurodegenerative diseases. Autophagy is a conserved catabolic process that targets cellular components for degradation. When autophagy is induced, membranes coalesce to engulf components targeted for degradation. Once these membranes seal to form an autophagosome their contents are delivered to the lysosome or vacuole for degradation. My laboratory has shown the importance of the Rab GTPase Ypt1 (Rab1 in mammals) in initiating these events. When cells are starved for nutrients, bulk autophagy is upregulated to rapidly make more nutrients. The high demand for membrane to make more autophagosomes during starvation leads to a dramatic reorganization of intracellular membranes. We have shown that the secretory pathway is downregulated during starvation and membranes from the secretory pathway are redirected to the bulk autophagy pathway. Furthermore, we found that phosphorylation of secretory machinery plays a key role in reprogramming membranes for bulk autophagy. A future goal of our studies is to identify the kinases that trigger the conserved membrane rearrangement events that take place during starvation in yeast (Saccharomyces cerevisiae) and mammalian cells. We will also address the requirements for fusing autophagosomal membranes with membranes from the early secretory pathway. Selective autophagy pathways use cargo receptors to degrade toxic aggregates and damaged organelle subdomains. These receptors link cargo, that is targeted for degradation, to the autophagy machinery. Our studies on autophagy have now expanded to include the selective degradation of the ER, also called ER-phagy. Understanding ER-phagy is of therapeutic importance as this pathway appears to be essential for the clearance of toxic aggregates from the ER. How ER-phagy targets damaged domains of the ER for degradation and severs these domains from the rest of the network remains unknown. We initiated a genetic screen in yeast and have identified key conserved factors that act in ER-phagy. Some of these factors are components of the early secretory pathway that also work in conjunction with Atg40. Atg40 is a conserved cargo receptor that has been implicated in the packaging of ER subdomains into autophagosomes. A goal of our studies is to understand how Atg40 works with these newly identified conserved components to target and sever ER subdomains during ER-phagy in both yeast and mammalian cells.