Defining the mechanism of starvation-induced ribophagy

项目摘要/摘要： MTORC1激酶复合体是细胞生长和新陈代谢的主要调节因子，在 各种常见的人类疾病，如糖尿病和癌症。此外，慢性mTOR抑制 延长各种模式生物的寿命。这些疾病的许多表型都被归因于 自噬在饥饿诱导的mTORC1抑制下游的作用。因此，理解 MTORC1对自噬的调控对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作用 核糖体对营养物质退化或mTOR抑制的反应。我们的推理是因为 核糖体占细胞总蛋白质和RNA的~50%和~80%，因此它们很可能被降解 对于在饥饿条件下维持细胞内环境平衡很重要。这个核糖体降解的过程 通过自噬(核吞噬)还没有完全被理解。我们最近发现NUFIP1是一种蛋白质，其 核功能与snoRNP介导的核糖体修饰有关，可以作为选择性 细胞质中核糖体的自噬受体。依赖NUFIP1的选择性自噬作用 在mTORC1途径下游，通过剥夺营养或用mTOR抑制剂诱导。目标是 这项拟议的研究的目的是定义NUFIP1识别核糖体的机制 降解，以及mTORC1如何参与调节这一信号。为此，我们提出如下建议 目标： 1.确定NUFIP1在核糖体上的结合部位。 2.确定饥饿调节的NUFIP1-核糖体所需的修饰或辅助蛋白 互动。 3.确定mTORC1信号如何启动选择性核噬菌体。 通过采取假设驱动和无偏见的方法，拟议的工作将定义 对饥饿作出反应的选择性噬核体。NUFIP1-核糖体结合部位及蛋白质的测定 参与标记核糖体以供降解可能会导致针对核糖体循环的新疗法。这 可能会对癌症等疾病产生影响，这些疾病利用自噬来保持其增殖潜力。

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.