Genetic Control of Purkinje Cell Degeneration

描述（由申请人提供）：在许多遗传和散发形式的神经变性中观察到错误折叠蛋白，并与多种神经元紊乱相关。在某些家族性疾病中，疾病相关蛋白质的错误折叠是由于编码该蛋白质的基因内的突变。然而，在其他神经退行性疾病中，特别是这些疾病的散发性、迟发性形式中，蛋白质错误折叠的机制在很大程度上仍然未知。我们的表型驱动方法已经确定了导致蛋白质错误折叠和神经退行性变的新型功能丧失突变。特别是，我们已经证明，编码丙氨酰tRNA合成酶（AlaRS）的基因中的编辑突变会导致tRNA错误充电和浦肯野细胞中错误折叠蛋白质的积累。重要的是，同样使用正向遗传方法，我们的实验室已经确定了一种新的基因Stim，它可以自主抑制这些神经元中蛋白质错误折叠的积累及其随后的退化。该提案描述了通过产生具有更严重的AlaRS编辑缺陷的小鼠来测试浦肯野细胞以外的神经元对误译的敏感性的实验。将在该模型中测试Stim在其他神经元中的功能。我们还将通过调节泛素/蛋白酶体系统来确定Stim在清除错误折叠蛋白中的作用。最后，将在该基因存在条件性无效突变的小鼠中评估Stim功能完全丧失的影响。 拟议研究与公共卫生的相关性：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，包括帕金森病、阿尔茨海默病、亨廷顿病和ALS。本提案中概述的实验将进一步定义一种新的基因，该基因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质的积累而发生的，小脑是控制运动协调的大脑区域。此外，该基因抑制大脑其他区域神经元功能障碍的能力也将被测试。这些实验的结果将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.