Molecular mechanisms that match lysosome function to cellular demand

描述（由申请人提供）：我们的长期目标是定义溶酶体活性是如何被调节的，并利用这种理解来制定策略来调节溶酶体的功能以达到治疗目的。溶酶体在大分子的细胞降解和由该过程释放的营养物质的再循环方面发挥着关键作用。转录因子TFEB已被确定为编码溶酶体蛋白的基因的主要调节因子。因此，调节TFEB活性的信号机制可能有助于溶酶体稳态的整体控制。本项目重点研究卵泡蛋白、Birt-Hogg-Dub综合征基因及其结合伙伴卵泡蛋白相互作用蛋白1 （FNIP1）在这一过程中所起的作用。我们提出的研究基于我们的新观察，FLCN和FNIP1定位于溶酶体，并对调节核TFEB水平有很强的影响。分别与细胞能量和营养稳态相关的AMPK和mTORC1信号通路都可能在FLCN和FNIP1的作用中发挥作用。我们提出的研究旨在了解：1)TFEB作为FLCN和FNIP1效应物在溶酶体功能调控中的作用；2)卵泡蛋白和FNIP1向溶酶体募集的基础；3) FLCN、FNIP1和AMPK之间的物理相互作用及其对该激酶在溶酶体表面募集的影响；4)溶酶体细胞质表面mTORC1活化的FLCN和fnip1依赖性调控。这些研究将利用我们在活细胞成像、蛋白-蛋白和蛋白-膜相互作用方面的专业知识，分析FLCN、FNIP1及其结合伙伴在溶酶体细胞质表面的动态募集，以及这种募集与其功能的关系。这项研究建立在对溶酶体底物降解和再循环在满足细胞能量和营养需求方面所起作用的日益认识的基础上，也强调了增强溶酶体功能的可能机会，这可能与神经退行性疾病的治疗有关。

DESCRIPTION (provided by applicant): Our long-term goal is to define how lysosome activity is regulated and to use this understanding to develop strategies to modulate lysosomal function for therapeutic purposes. Lysosomes perform critical functions with regard to the cellular degradation of macromolecules and the recycling of the nutrients that are liberated by this process. The transcription factor TFEB has been identified as a major regulator of genes encoding lysosomal proteins. Thus, the signaling mechanisms that regulate TFEB activity could contribute to the overall control of lysosome homeostasis. This project focuses on the role played by folliculin, the Birt-Hogg-Dub¿ syndrome gene, and its binding partner folliculin interacting protein 1 (FNIP1) in this process. The proposed research builds on our novel observations that FLCN and FNIP1 localize to lysosomes and have a strong influence on regulating the nuclear levels of TFEB. Both the AMPK and mTORC1 signaling pathways that are related to cellular energy and nutrient homeostasis respectively may play a role in this action of FLCN and FNIP1. Our proposed research seeks to understand: 1) the role for TFEB as a FLCN and FNIP1 effector in the regulation of lysosome function; 2) the basis for the recruitment of folliculin and FNIP1 to lysosomes; 3) the physical interactions between FLCN, FNIP1 and AMPK and their effects on the recruitment of this kinase to the surface of lysosomes; and 4) the FLCN and FNIP1-dependent regulation of mTORC1 activation at the cytoplasmic surface of lysosomes. These studies will take advantage of our expertise in live cell imaging, protein-protein and protein-membrane interactions to analyze the dynamic recruitment of FLCN, FNIP1 and their binding partners to the cytoplasmic surface of lysosomes and the relationship of such recruitment to their function. This research builds on a growing appreciation of the role played by degradation and recycling of lysosomal substrates for meeting the energy and nutrient demands of cells and also highlights possible opportunities for the enhancement of lysosome function that could be relevant for the treatment of neurodegenerative diseases.