Defining the Nucleophagy Mechanism: Opening New Doors for Aging Research

项目摘要 在过去的10年里，溶酶体介导的降解途径巨自噬已经得到了重视 研究衰老相关疾病和延长寿命。巨自噬是一种重要的细胞 负责消除胞质蛋白质、脂质和细胞器的途径，因此，该领域具有 专注于大自噬在清除蛋白质聚集体或功能失调的细胞器（如 线粒体），其特异性地积聚在细胞质中。然而，越来越多的蛋白质积累和 观察到细胞器功能障碍发生在细胞核内，显然与细胞质屏蔽 由双层膜核膜突起。此外，衰老与核之间的联系 包膜结构缺陷正在出现，包括由细胞膜蛋白突变引起的细胞核病变。 包被骨架片层。细胞如何对这些核损伤作出反应还不清楚， 有趣的是，核纤层蛋白似乎受到大自噬依赖性周转的影响。因此，很明显，我们必须 重新关注如何执行核质量控制，特别是 控制细胞质自噬体中的核内容物周转。因此，在本提案中，我们将重点放在 细胞质自噬机制和核膜重塑是如何 协调一致。利用S.酿酒酵母，在那里发现的分子机制驱动核自噬是 最成熟的，我们将揭示每一个复杂的膜动力学事件，发生移动核 被膜碎片离开核，最终进入液泡降解。然后我们将 建立膜重塑的机制，使用完全重建的系统， 两个核膜中的每一个的拓扑同一性。重要的是，在这些重组中， 系统，我们还将引入生长自噬体的分子模拟物， 的核小体自噬体接口，管理核包膜碎片的隔离。 随着这个项目的完成，我们将进一步了解一个关键的未得到重视的机械 巨自噬过程，并进一步了解核自噬如何影响衰老受损 蛋白质稳态

Project Summary Over the last 10 years, the lysosome-mediated degradation pathway macroautophagy has gained prominence in the study of aging-related disorders and extension of lifespan. Macroautophagy is an essential cellular pathway responsible for the elimination of cytosolic proteins, lipids and organelles, and as such, the field has focused upon the role of macroautophagy in clearing protein aggregates or dysfunctional organelles (such as mitochondria) that specifically accumulate in the cytoplasm. Increasingly however, protein accumulation and organelle dysfunction are observed to occur within the nucleus, apparently shielded from cytoplasmic processes by the double-membraned nuclear envelope. Furthermore, links between aging and nuclear envelope structural defects are emerging, including nuclear envelopathies caused by mutations in the envelope scaffolding lamins. How the cell responds to these nuclear insults is not well understood, but intriguingly, lamins appear to be subject to macroautophagy-dependent turnover. Thus, it is clear that we must refocus our attention on how nuclear quality control is executed and specifically on the mechanism(s) that governs nuclear content turnover in cytoplasmic autophagosomes. Thus, in this proposal, we focus on the fundamental question of how cytoplasmic autophagy machinery and nuclear envelope remodeling are coordinated. Using S. cerevisiae, where discovery of the molecular machinery driving nuclear autophagy is the most mature, we will reveal each of the complex membrane dynamics events that occur to move nuclear envelope fragments away from the nucleus and eventually into the vacuole for degradation. We will then establish the mechanism of membrane remodeling, using fully reconstituted systems that maintain the topologic identity of each of the two nuclear envelope membranes. Importantly, within these reconstituted systems we will also introduce molecular mimics of the growing autophagosome and recapitulate the formation of the nuclear envelope-autophagosome interface that governs sequestration of nuclear envelope fragments. With the completion of this project, we will further our mechanistic understanding of a key underappreciated macroautophagic process and further our understanding of how nuclear autophagy can impact aging-impaired proteostasis.