Molecular mechanisms that match lysosome function to cellular demand

项目摘要/摘要 溶酶体是大分子降解的主要场所，并在 细胞感知并对细胞内养分供应的变化做出反应。相反，细胞内的水平 氨基酸等营养物质调节溶酶体的特性，包括它们的生物发生、酸化、信号转导 功能和亚细胞位置。定义了允许这种协调的分子机制 具有营养有效性的溶酶体功能对于解开溶酶体如何维持体内动态平衡至关重要 健康和疾病。该项目的重点是由C9orf72、SMCR8和C9orf72组成的异三聚体蛋白质复合体。 WDR41。我们对这种蛋白质复合体的兴趣源于我们的发现，它被招募到溶酶体上 氨基酸缺乏，这是溶酶体降解功能以及它们的能力所必需的 支持在急性暴露于氨基酸的情况下激活mTORC1。因此，我们提出的研究 试图：1)阐明细胞与氨基酸可获得性变化的感知相结合的机制 与C9orf72-SMCR8-WDR41募集到溶酶体有关。2)确定C9orf72的直接溶酶体靶点 SMCR8-WDR41。3)确定这一整体途径如何整合到溶酶体的维持中 动态平衡。虽然我们的研究重点是使用人类细胞模型来确定本质 这个蛋白复合体的溶酶体相关功能，我们预计我们的发现将对 了解细胞在正常生理和疾病中对溶酶体功能障碍的反应。特别是， C9orf72基因非编码区六核苷酸重复序列的扩张是最常见的家族性疾病 到目前为止，额颞部痴呆(FTD)和肌萎缩侧索硬化症(ALS)的病因已被确定。海流 缺乏对C9orf72蛋白功能的了解是了解其潜在影响的主要障碍 在这些神经退行性疾病的发展过程中C9orf72蛋白水平降低。我们的结果是 实验有望产生C9orf72的直接靶点，从而为 在神经退行性疾病的背景下对它们的调节失调进行评估。超越具体的解决方案 C9orf72蛋白功能与神经退行性疾病的问题及基础阐明 将溶酶体功能与细胞需求的持续变化相匹配的机制具有广泛的细胞生物学意义 对多种生理和病理背景具有潜在相关性的重要性。

Project Summary/Abstract Lysosomes serve as a major site for the degradation of macromolecules and play a central role in the ability of cells to sense and respond to changes in intracellular nutrient availability. Conversely, levels of intracellular nutrients such as amino acids regulate lysosomal properties, including their biogenesis, acidification, signaling functions and subcellular position. Defining the molecular machinery that allows for this coordination of lysosome function with nutrient availability is critical for unraveling how lysosome homeostasis is maintained in health and disease. This project focuses on a heterotrimeric protein complex made up of C9orf72, SMCR8 and WDR41. Our interest in this protein complex stems from our discoveries that it is recruited to lysosomes upon amino acid deprivation and is required for both degradative functions of lysosomes as well as their ability to support activation of mTORC1 in response to acute exposure to amino acids. Our proposed research thus seeks to: 1) Elucidate the mechanisms whereby cells couple the sensing of changes in amino acid availability to the recruitment of C9orf72-SMCR8-WDR41 to lysosomes. 2) Define the direct lysosomal targets of C9orf72- SMCR8-WDR41. 3) Establish how this overall pathway is integrated into the maintenance of lysosome homeostasis. While our research focuses on using human cellular models to determine the essential lysosome-related functions of this protein complex, we anticipate that our findings will have broad relevance for understanding how cells respond to lysosome dysfunction in both normal physiology and disease. In particular, expansion of a hexanucleotide repeat in a non-coding region of the C9orf72 gene is the most common familial cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) identified to date. The current lack of understanding of C9orf72 protein function is a major obstacle to understanding the potential impact of reduced C9orf72 protein levels in the development of these neurodegenerative diseases. The results of our experiments are expected to yield direct targets of C9orf72 and will thereby provide a foundation for the evaluation of their dysregulation in the context of neurodegenerative disease. Beyond addressing specific questions about C9orf72 protein function and neurodegenerative disease, elucidation of fundamental mechanisms that match lysosome function to ongoing changes in cellular demand is of broad cell biological importance with potential relevance for multiple physiological and pathological contexts.