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

项目摘要 这项研究的目的是了解分泌机制在两种不同的细胞中的作用。 使用自噬体的自噬途径的类型，大量自噬和选择性自噬 内质网（ER）。自噬的缺陷与癌症和各种人类疾病有关。 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， 降解的细胞成分。当自噬被诱导时，细胞膜会合并以吞噬细胞成分 以降解为目标。一旦这些膜密封形成自噬体， 到溶酶体或液泡中降解。我的实验室已经证明了Rab GTIPYPT 1的重要性 (Rab1在哺乳动物中）在启动这些事件中。 当细胞缺乏营养时，大量自噬被上调以迅速产生更多的营养。的 在饥饿期间，为了制造更多的自噬体，对膜的更高需求导致了 细胞内膜的重组。我们已经表明，分泌途径下调， 饥饿和来自分泌途径的膜被重定向到大量自噬途径。 此外，我们发现分泌机制的磷酸化在重编程中起关键作用 大量自噬的细胞膜。我们研究的一个未来目标是确定触发保守的 在酵母（酿酒酵母）中饥饿期间发生的膜重排事件， 哺乳动物细胞我们还将讨论融合自噬体膜的要求， 膜从早期分泌途径。 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 细胞器子域。这些受体将降解的目标货物与自噬联系起来， 机械.我们对自噬的研究现在已经扩展到包括ER的选择性降解， 叫做ER-phagy。理解ER-吞噬具有治疗重要性，因为该途径似乎是 对于从ER中清除有毒聚集物至关重要。ER-吞噬如何靶向受损的 ER的降级和切断这些域从网络的其余部分仍然是未知的。我们发起了一个 在酵母中进行遗传筛选，并鉴定了在ER-吞噬中起作用的关键保守因子。其中一些因素 是早期分泌途径的组成部分，也与Atg 40一起工作。Atg 40是一个保守的 在ER亚结构域包装成自噬体中有牵连的货物受体。的目标 我们的研究是了解Atg 40如何与这些新发现的保守组分一起作用， 在酵母和哺乳动物细胞中ER-吞噬过程中存在几个ER亚结构域。

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.