Genetic Control of Purkinje Cell Degeneration

描述(由申请人提供)：错误折叠的蛋白质在许多遗传和零星形式的神经变性中被观察到，并与多个神经元障碍有关。在一些家族性疾病中，与疾病相关的蛋白质的错误折叠是由于编码蛋白质的基因发生突变。然而，其他神经退行性疾病中蛋白质错误折叠的机制，特别是这些疾病的零星、晚发形式，在很大程度上仍不清楚。我们的表型驱动的方法已经发现了导致蛋白质错误折叠和神经退化的新的功能丧失突变。特别是，我们已经证明，编码丙氨酰tRNA合成酶(AlaRS)的基因的编辑突变导致tRNA错误充电和错误折叠的蛋白质在Purkinje细胞中积累。重要的是，同样使用正向遗传学方法，我们的实验室已经确定了一个新的基因，STIM，它在细胞自主地抑制蛋白质错误折叠在这些神经元中的积累和随后的退化。这项建议描述了一种实验，通过产生一只在AlaRS编辑方面存在更严重缺陷的小鼠，来测试浦肯野细胞以外的神经元对误翻译的敏感性。STIM在其他神经元中的功能将在这个模型中进行测试。我们还将通过调节泛素/蛋白酶体系统来确定STIM在清除错误折叠的蛋白质中的作用。最后，将在该基因有条件性零突变的小鼠身上评估STim功能完全丧失的影响。 拟议的研究与公共健康的相关性：神经元中异常蛋白质的积累与许多人类神经退行性疾病有关，包括帕金森氏病、阿尔茨海默病、亨廷顿病和ALS。这项提案中概述的实验将进一步定义一种新的基因，它可以抑制神经元死亡和伴随的运动异常，这些异常是由于小脑中浦肯野神经元中异常蛋白的积累而发生的，小脑是大脑中控制运动协调的区域。此外，还将测试该基因抑制大脑其他区域神经元功能障碍的能力。这些实验的结果可能会为神经元退行性疾病提供新的治疗靶点。

DESCRIPTION (provided by applicant): Misfolded proteins are observed in many genetic and sporadic forms of neurodegeneration and are associated with multiple neuronal disturbances. In some familial forms of disease, misfolding of the disease-related protein is due to mutations within the gene that encodes the protein. However, the mechanisms that underlie protein misfolding in other neurodegenerative diseases, in particular the sporadic, late-onset forms of these disorders, remain largely unknown. Our phenotype-driven approach has identified novel loss-of-function mutations that result in protein misfolding and neurodegeneration. In particular we have demonstrated that an editing mutation in the gene encoding alanyl tRNA synthetase (AlaRS) causes tRNA mischarging and accumulation of misfolded proteins in Purkinje cells. Importantly, also using a forward genetic approach, our laboratory has identified a novel gene, Stim, which cell-autonomously suppresses the accumulation of protein misfolding in these neurons and their subsequent degeneration. This proposal describes experiments to test the sensitivity of neurons, other than Purkinje cells, to mistranslation, via the generation of a mouse with a more severe deficiency in AlaRS editing. The function of Stim in other neurons will be tested in this model. We will also establish the role of Stim in the clearance of misfolded proteins via modulation of ubiquitin/proteasome system. Lastly, the effects of complete loss of Stim function will be assessed in mice with a conditional null mutation in this gene. Relevance of the proposed research to public health: The accumulation of abnormal proteins in neurons is associated with many human neurodegenerative disorders, including Parkinson's disease, Alzheimer's disease, Huntington's disease and ALS. The experiments outlined in this proposal will further define a novel gene that suppresses neuron death and the accompanying movement abnormalities that occur in response to the accumulation of abnormal proteins in Purkinje neurons in the cerebellum, the region of the brain that controls motor coordination. In addition, the ability of this gene to suppress neuronal dysfunction in other regions of the brain will be tested. The results from these experiments will potentially provide novel therapeutic targets for neuronal degenerative disorders.