Genetic Control of Purkinje Cell Degeneration

描述（由申请人提供）：在许多遗传性和散发性神经变性中观察到错误折叠的蛋白质，并与多种神经元紊乱有关。在一些家族性疾病中，疾病相关蛋白的错误折叠是由于编码该蛋白的基因发生突变。然而，其他神经退行性疾病中蛋白质错误折叠的机制，特别是这些疾病的散发性、迟发性形式，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变性的新型功能丧失突变。特别是，我们已经证明了编码丙烯基tRNA合成酶（AlaRS）的基因的编辑突变导致浦肯野细胞中tRNA错误充电和错误折叠蛋白的积累。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，它可以细胞自主地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。该提案描述了通过培养具有更严重AlaRS编辑缺陷的小鼠来测试除浦肯野细胞以外的神经元对误翻译的敏感性的实验。Stim在其他神经元中的功能将在该模型中进行测试。我们还将通过调节泛素/蛋白酶体系统来确定Stim在清除错误折叠蛋白中的作用。最后，将在该基因有条件null突变的小鼠中评估Stim功能完全丧失的影响。

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.