Molecular mechanisms that match lysosome function to cellular demand

描述（由申请人提供）：我们的长期目标是确定溶酶体活性是如何调节的，并使用这种理解来开发用于治疗目的的调节溶酶体功能的策略。溶酶体在大分子的细胞降解和通过该过程释放的营养物质的再循环方面发挥关键作用。转录因子TFEB已被鉴定为编码溶酶体蛋白的基因的主要调节因子。因此，调节TFEB活性的信号传导机制可能有助于溶酶体稳态的总体控制。该项目的重点是卵泡素，Birt-Hogg-Dub <$syndrome基因，及其结合伴侣卵泡素相互作用蛋白1（FNIP 1）在这一过程中发挥的作用。这项研究建立在我们的新观察基础上，即FLCN和FNIP 1定位于溶酶体，对调节TFEB的核水平有很强的影响。AMPK和mTORC 1信号通路分别与细胞能量和营养稳态相关，可能在FLCN和FNIP 1的这种作用中发挥作用。我们的研究旨在了解：1）TFEB作为FLCN和FNIP 1效应子在调节溶酶体功能中的作用; 2）滤泡素和FNIP 1募集到溶酶体的基础; 3）FLCN、FNIP 1和AMPK之间的物理相互作用及其对该激酶募集到溶酶体表面的影响;和4）FLCN和FNIP 1依赖性调节mTORC 1在溶酶体胞质表面的活化。这些研究将利用我们在活细胞成像，蛋白质-蛋白质和蛋白质-膜相互作用方面的专业知识，分析FLCN，FNIP 1及其结合伴侣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的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重视的基础上，并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.