Alpha-synuclein degradation mechanisms

描述（由申请人提供）：α-突触核蛋白（α-syn）突变或基因扩增引起帕金森病（PD）的一小部分，伴有路易体（LB）形成、神经变性和通常相关的痴呆。LB中的α-syn聚集也广泛存在于散发性PD和其他LB疾病中，而没有明显的转录上调。在各种动物模型中，α-syn过表达导致其聚集和/或神经毒性。α-syn的减少在动物模型中具有神经保护作用。这些观察结果表明减少a-syn在治疗PD和其他LB疾病中具有治疗潜力。我们的长期目标是确定神经退行性疾病中α-突触核蛋白病的机制和调控，并提供新的有效的治疗策略。我们专注于溶酶体在调节神经元a-syn聚集和毒性中的功能，因为溶酶体是负责清除受损和聚集的蛋白质的高容量细胞器，并且与衰老和几种神经退行性疾病有关。我们发现，具有溶酶体组织蛋白酶D（CD）缺陷的小鼠在脑中表现出显著的a-syn积累，表明CD在介导a-syn代谢中的关键作用。在体外，我们已经表明CD的过表达减少了α-syn聚集并保护免受α-syn介导的毒性。为了进一步确立CD作为抗α-突触核蛋白病的治疗靶点，我们将检查其体内作用，并确定其体外作用机制。我们假设CD通过增加a-syn毒性物质的自噬清除来保护a-syn神经毒性。我们将通过以下目的的实验来验证这一假设：1。检验CD单倍不足增加对体内α-syn诱导的神经毒性的敏感性的假设。2.测试AAV-CD向SN的立体定位递送在体内减弱α-syn介导的神经毒性的假设。3.检验CD的神经保护作用是通过自噬清除α-syn的假设。这些研究的完成将确定CD的部分损失在α-syn诱导的DA神经元死亡中的作用，以及CD的功能获得在体内神经保护中的作用。此外，深入了解CD介导的神经保护作用的潜在分子机制和易聚集蛋白的清除的分子机制和调节，将获得将允许CD治疗策略的进一步完善。

DESCRIPTION (provided by applicant): a-synuclein (a-syn) mutations or gene amplification cause a small subset of Parkinson's disease (PD), with Lewy body (LB) formation, neurodegeneration and often an associated dementia. a-syn aggregation in LB is also widespread in sporadic PD and other LB diseases without apparent upregulation of transcription. a-syn overexpression leads to its aggregation and/or neurotoxicity in various animal models. Reduction of a-syn is neuroprotective in animal models. These observations suggest a therapeutic potential of reducing a-syn in treatment of PD and other LB diseases. Our long-term objective is to determine the mechanisms and regulation of a-synucleinopathy in neurodegenerative diseases, and to provide novel and effective treatment strategies. We focused on the lysosomal function in modulating neuronal a-syn aggregation and toxicity, because lysosomes are high capacity organelles responsible for clearance of damaged and aggregated proteins, and are implicated in aging and several neurodegenerative diseases. We found that mice with deficient lysosomal cathepsin D (CD) exhibited significant a-syn accumulation in the brains, indicating a critical role for CD in mediating a-syn metabolism. In vitro we have shown that overexpression of CD reduces a-syn aggregation and protects against a-syn-mediated toxicity. To further establish CD as a therapeutic target against a-synucleinopathy, we will examine its effects in vivo, and define the mechanisms of its action in vitro. We hypothesize that CD protects against a-syn neurotoxicity by increasing autophagic clearance of toxic species of a-syn. We will test this hypothesis by performing experiments with the following aims: 1. Test the hypothesis that CD haploinsufficiency increases sensitivity to a-syn-induced neurotoxicity in vivo. 2. Test the hypothesis that stereotaxic delivery of AAV-CD to the SN attenuates a-syn-mediated neurotoxicity in vivo. 3. Test the hypothesis that neuroprotection by CD is through clearance of a-syn by autophagy. Completion of these studies will determine the effect of partial loss-of-CD in a-syn-induced DA neuron death, and the effect of gain-of-function of CD in neuroprotection in vivo. Furthermore, insights into the potential molecular mechanisms of CD-mediated neuroprotection and the molecular mechanisms and regulation of clearance of aggregation-prone proteins, will be gained that will permit further refinement of CD therapeutic strategies.