Rhes-SUMO circuitry in Huntington's Disease Pathogenesis

 描述（申请人提供）：亨廷顿病（HD）是一种常染色体显性遗传神经退行性疾病，由亨廷顿蛋白（mHtt）中的多聚谷氨酰胺重复序列扩增引起，表现为舞蹈病性运动障碍、人格改变、行为异常和认知退化。除对症治疗外，HD无疾病缓解治疗。虽然mHtt在脑和外周组织中普遍表达，但它主要引起纹状体组织中的神经元损失和损伤，这是一个知之甚少的过程。因此，需要研究确定导致纹状体变性的机制，以开发预防和/或延迟HD发作的新药。我们的长期目标是了解纹状体特异性蛋白在HD发病机制中的作用，以达到预防和治疗的目的。这里的目标，这是追求这一目标的下一步，是剖析含有SUMO E3连接酶活性的Rhes GTdR在HD发病机制中的机制，并鉴定其生理SUMO底物。我们的中心假设是，Rhes-SUMO 1-mHtt-mTORC 1电路elevated线粒体损伤和HD发病机制。这一假设是在我们以前的研究、新数据和初步结果的基础上提出的。我们的目的是：1：研究Rhes-SUMO-mHtt-mTORC 1通路在线粒体功能障碍中的作用。多项研究支持Rhes在HD中的作用，但机制尚不清楚。在这里，我们将解剖的机制，使用纹状体细胞，专注于Rhes-SUMO 1在mTORC 1活性和线粒体功能障碍;和2：挑战SUMO 1的缺失在改善HD发病机制的小鼠。尽管已知SUMO 1在mHtt诱导的细胞毒性中的作用，但其在哺乳动物HD发病机制中的作用仍然未知。我们将SUMO 1-/-小鼠与N171 HD小鼠杂交以阐明行为和病理结果;和3：鉴定Rhes的SUMO化底物。除了SUMOylating mHtt，Rhes生理SUMOylates几个纹状体蛋白，但他们的身份仍然未知。使用细胞培养，体外SUMO化测定，和蛋白质组学方法，我们将确定潜在的SUMO底物Rhes。总的来说，该项目是创新的，因为它采用了跨学科的方法，利用小鼠遗传学，细胞生物学，生物化学和行为学的工具来剖析导致纹状体特异性细胞丢失的途径。该项目的结果 将是重要的，因为它将推进我们对纹状体组织为什么以mHtt依赖性方式优先ost的理解，并为开发靶向HD中Rhes信号传导的药物提供原理证明。

 DESCRIPTION (provided by applicant): Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by expansion of a polyglutamine repeat in the protein huntingtin (mHtt), and is manifested by choreatic dyskinesias, personality changes, abnormal behaviors and cognitive deterioration. With the exception of symptomatic treatments there are no disease-modifying therapies for HD. Although mHtt is expressed ubiquitously in brain and peripheral tissue, it predominantly causes neuronal loss and damage in striatal tissue, a process that is poorly understood. Therefore, studies that define the mechanisms that contribute to the striatal degeneration are needed to develop new drugs that prevent and/or delay the onset of HD. Our long-term goal is to understand the role of striatal-specific proteins in HD pathogenesis for preventive and therapeutic purposes. The objective here, which is next step in pursuit of that goal, is to dissect the mechanisms of Rhes GTPase, that contains SUMO E3 ligase activity, in HD pathogenesis, and to identify its physiological SUMO substrates. Our central hypothesis is that Rhes-SUMO1-mHtt-mTORC1 circuitry elicits mitochondrial damage and HD pathogenesis. This hypothesis is formulated on the basis of our previous studies, new data and preliminary results. Our Aims are: 1: Dissect the role of Rhes-SUMO-mHtt-mTORC1 circuitry in mitochondrial dysfunction. Multiple studies support the role of Rhes in HD, but the mechanisms are unknown. Here we will dissect the mechanisms, using striatal cells, focusing on the Rhes-SUMO1 in mTORC1 activity and mitochondrial dysfunction; and 2: Challenge the deletion of SUMO1 in the amelioration of HD pathogenesis in mice. Despite known roles for SUMO1 in mHtt-induced cellular toxicity, its role in the pathogenesis of HD in mammal remains unknown. We will cross SUMO1-/- mice with N171HD mouse to elucidate behavioral and pathological outcomes; and 3: Identify SUMOylation substrates for Rhes. Besides SUMOylating mHtt, Rhes physiologically SUMOylates several striatal proteins, but their identity remains unknown. Using cell culture, in vitro SUMOylation assay, and proteomic approaches we will identify potential SUMO substrates for Rhes. Overall, the project is innovative because it employs an interdisciplinary approach, utilizing tools from mouse genetics, cell biology, biochemistry, and behavior to dissect the pathway leading to striatal-specific cell loss. The results of this project will be significant, as it will advance our understanding of why striatal tissue is preferentially ost in an mHtt- dependent fashion and provide proof-of-principle for the development of drugs targeting Rhes signaling in HD.