Defining the mechanism of starvation-induced ribophagy

项目概要/摘要： mTORC 1激酶复合物是细胞生长和代谢的主要调节因子， 糖尿病和癌症等多种常见人类疾病。此外，慢性mTOR抑制 增加了各种模式生物的寿命。这些疾病表型中的许多被归因于 自噬在饥饿诱导的mTORC 1抑制下游的作用。因此了解 通过mTORC 1调节自噬对于指导未来的治疗和揭示 基本的细胞生物学过程。我们特别感兴趣的是自噬介导的 核糖体降解响应于营养恶化或mTOR抑制。我们这么推断是因为 核糖体占总细胞蛋白质和RNA的~50%和~80%，它们的降解可能是 对于在饥饿条件下维持细胞内稳态很重要。这个核糖体降解的过程 通过自噬（ribophagy）的作用，目前还没有完全了解。我们最近发现，NUFIP 1，一种蛋白质， 核功能与snoRNP介导的核糖体修饰有关，可以作为选择性的 细胞质中核糖体的自噬受体。依赖NUFIP 1的选择性自噬作用 在mTORC 1通路的下游，并且通过营养剥夺或用mTOR抑制剂诱导。目标 这项研究的目的是确定NUFIP 1识别核糖体的机制， 降解，以及mTORC 1如何参与介导该信号。为此，我们提出以下建议 目的： 1.确定NUFIP 1在核糖体上的结合位点。 2.鉴定饥饿调节NUFIP 1-核糖体所需的修饰或辅助蛋白 互动 3.确定mTORC 1信号传导如何启动选择性核糖体吞噬。 通过采取假设驱动和无偏的方法，拟议的工作将定义 对饥饿的选择性摄食。确定NUFIP 1-核糖体结合位点以及蛋白质 参与标记核糖体降解可能导致新的治疗靶向核糖体回收。这 可能会对癌症等疾病产生影响，这些疾病选择自噬来维持其增殖潜力。

Project Summary/Abstract: The mTORC1 kinase complex is a major regulator of cell growth and metabolism, and is deregulated in a variety of common human diseases such as diabetes and cancer. In addition, chronic mTOR inhibition increases lifespan in a variety of model organisms. Many of these disease phenotypes have been attributed to the role of autophagy downstream of starvation-induced mTORC1 inhibition. Therefore, understanding the regulation of autophagy by mTORC1 is of great importance to guide future therapeutics and to uncover fundamental cellular biological processes. Of particular interest to us is the role of autophagy-mediated degradation of ribosomes in response to nutrient depravation or mTOR inhibition. We reasoned that because ribosomes make up ~50% and ~80% of the total cellular protein and RNA, that their degradation is likely important for maintaining cellular homeostasis under starvation conditions. This process of ribosome degradation via autophagy (ribophagy) is yet to be fully understood. We recently discovered that NUFIP1, a protein whose nuclear function is associated with snoRNP mediated modification of the ribosome, can act as a selective autophagy receptor for ribosomes in the cytoplasm. NUFIP1-dependent selective autophagy operates downstream of the mTORC1 pathway and is induced via nutrient deprivation or with mTOR inhibitors. The goal of the proposed research is to define the mechanism by which NUFIP1 recognizes ribosomes for degradation, and how mTORC1 is involved in mediating this signal. To that end we propose the following aims: 1. Determine the binding site of NUFIP1 on the ribosome. 2. Identify the modification or accessory protein needed for the starvation regulated NUFIP1-ribosome interaction. 3. Determine how mTORC1 signaling initiates selective ribophagy. By taking both hypothesis driven and unbiased approaches, the proposed work will define the mechanism of selective ribophagy in response to starvation. Determining the NUFIP1-ribosome binding site as well as proteins involved in marking ribosomes for degradation may lead to novel therapies targeting ribosome recycling. This could have implications for diseases like cancer that co-opt autophagy to maintain their proliferative potential.