Molecular Genetic Analysis of TORC1 and TORC2 Signaling in Neuronal Maintenance

项目摘要 帕金森氏病（PD）等帕金森病相关的神经退行性疾病给人类带来了巨大的社会经济损失。 由于缺乏改善疾病的治疗选择而造成的负担。线粒体功能障碍与 神经退行性疾病线粒体异常是如何产生的，以及它们如何与其他特征相关。 神经退行性疾病，如蛋白质稳态失败、Ca 2+稳态失调和神经炎症， 明白对线粒体结构、功能和分布的动态控制对于正常发育也是必不可少的。 神经元的高度极化的形状和独特的生理需要。 尽管做了大量的努力，但关于线粒体与细胞质之间的相互作用机制， 调节神经元的维持。Pten诱导的激酶1（PINK 1）和Parkin（编码E3泛素连接酶）， 与家族性PD相关的两个基因，已经确定了一个重要的线粒体和神经元的遗传途径， 在苍蝇和哺乳动物中维持。识别这一途径提供了一个非常需要的切入点，以了解 调节线粒体功能以响应神经元活动和代谢需要，并破译线粒体的功能。 线粒体功能障碍和疾病的其他病理标志之间的机械联系。我们的基因研究 揭示了PINK 1/Parkin指导了一个相互关联的线粒体质量控制（MQC）过程，这对 多巴胺能（DA）神经元的维持。多方面的MQC过程包括翻译控制， 呼吸链复合体（RCC）生物发生，线粒体分裂/融合动力学，运输和清除 线粒体自噬（mitophagy）。在过去的资助期间，我们已经表明， 雷帕霉素复合物的靶点（TORC 1和TORC 2）充当PINK 1定向MQC的重要介体。一 我们的研究中令人兴奋的发现是PINK 1/mTORC 2通路对核转录的翻译控制， 编码的RCC（nRCC）mRNA。该提案的目标是摆脱以线粒体自噬为中心的现状， 通过关注新发现的PINK 1/mTORC 2的翻译控制功能，关注PINK 1指导的MQC 发信号。我们将使用分子遗传学、基因组学、细胞生物学和生物化学工具的独特组合， 并且在体内果蝇模型和体外诱导的DA神经元（iDN）模型之间移动。我们的核心假设是， PINK 1/mTORC 2信号通过核糖体相关共翻译调节DA神经元功能和存活 选择核编码的线粒体mRNA的质量控制（RQC），从而机械地连接线粒体 蛋白质稳态的功能。我们建议阐明RQC途径如何介导的影响， PINK 1/mTORC 2对线粒体调节和DA神经元维持（Aim 1）的作用，并分析其分子机制。 PINK 1/mTORC 2信号在果蝇模型和患者源性iDN中的RQC调节机制 模型（目标2）。这些研究将大大推进我们对PINK 1/mTORC 2信号传导机制的理解。 调节DA神经元的稳态，揭示了神经元脆弱的现象， RQC失败，并可能导致PD和其他神经系统疾病的新的和合理的治疗。

Project Summary Age-related neurodegenerative diseases such as Parkinson's disease (PD) impose tremendous socioeconomic burdens due to the lack of disease-modifying treatment options. Mitochondrial dysfunction is intimately linked to neurodegenerative diseases. How mitochondrial abnormalities arise and how they relate to other features of neurodegenerative diseases such as proteostasis failure, Ca2+ dyshomeostasis, and neuroinflammation are poorly understood. Dynamic control of the structure, function, and distribution of mitochondria is also essential for normal neuronal function, a requirement necessitated by the highly polarized shape and unique physiology of neurons. Despite intensive efforts, many fundamental questions remain regarding the mechanisms linking mitochondrial regulation to neuronal maintenance. Pten-induced kinase 1(PINK1) and Parkin (encoding an E3 ubiquitin ligase), two genes associated with familial PD, have defined a genetic pathway important for mitochondrial and neuronal maintenance in flies and mammals. Identification of this pathway offers a much-needed entry point to understand the regulation of mitochondrial function in response to neuronal activity and metabolic needs, and to decipher the mechanistic link between mitochondrial dysfunction and other pathological hallmarks of disease. Our genetic studies revealed that PINK1/Parkin directs an interconnected mitochondrial quality control (MQC) process important for the maintenance of dopaminergic (DA) neurons. The multifaceted MQC process encompasses translational control of respiratory chain complex (RCC) biogenesis, mitochondrial fission/fusion dynamics, transport, and removal of defective mitochondria by autophagy (mitophagy). In the past funding period we have shown that the conserved target of rapamycin complexes (TORC1 and TORC2) act as important mediators of PINK1-directed MQC. One exciting finding from our investigation is that the PINK1/mTORC2 pathway exerts translational control of nuclear encoded RCC (nRCC) mRNAs. The goal of this proposal is to move away from the status quo of mitophagy-centric focus of PINK1-directed MQC by focusing on the newly discovered translational control function of PINK1/mTORC2 signaling. We will use a unique combination of molecular genetic, genomic, cell biological, and biochemical tools, and move between in vivo fly models and in vitro induced DA neuron (iDN) models. Our central hypothesis is that PINK1/mTORC2 signaling regulates DA neuron function and survival through ribosome-associated co-translational quality control (RQC) of select nuclear-encoded mitochondrial mRNAs, thus mechanistically linking mitochondrial function to protein homeostasis. We propose to elucidate how the RQC pathway mediates the effects of PINK1/mTORC2 on mitochondrial regulation and DA neuron maintenance (Aim 1), and dissect the molecular mechanism of RQC regulation by PINK1/mTORC2 signaling in both Drosophila models and patient-derived iDN models (Aim 2). These studies will significantly advance our understanding of how PINK1/mTORC2 signaling regulates DA neuron homeostasis, shed light on the poorly understood phenomenon of neuronal vulnerability to RQC failure, and potentially lead to novel and rational therapy for PD and other neurological disease conditions.