Mechanisms of synaptic dysfunction in Parkinson's and other synuclein-linked diseases

这个项目的长期目标是确定引起 帕金森氏病(PD)、路易体痴呆(DLB)及其变异体的突触缺陷 阿尔茨海默病(AD)，并制定逆转这些疾病的策略。一个病态的标志 这些疾病是α-突触核蛋白在包括突触在内的神经元中的聚集。突触 α-突触核蛋白的聚集被认为是认知缺陷和痴呆的原因。虽然它是 普遍认为α-突触核蛋白聚集在突触会损害囊泡的内吞作用， 潜在的机制仍不清楚。因此，目前还没有已知的改进策略 PD、DLB或AD的突触功能，因为我们不知道细胞或分子靶点。这个 拟议的实验通过利用两个经典的 脊椎动物突触非常适合研究突触囊泡运输，并通过使用两者 α-突触核蛋白的急性和遗传扰动。该方法包括定量和定量相结合 生化、电生理和成像分析。α-突触核蛋白毒性的一个模型表明 它是由异常低聚物的形成引发的，而另一种观点认为 单体是触发因素。Aim 1将通过确定如何在突触上测试这两个模型的预测 α-突触核蛋白的特定分子种类(单体、二聚体、高分子量低聚物)会影响 囊泡运输和神经传递及其潜在机制。初步研究表明 单体和二聚体产生不同的效果。目标2中的实验将确定α的作用- 通过检测干扰突触缺陷的试剂，突触核蛋白在产生突触缺陷中的自结合 过程，包括一种具有潜在治疗价值的药物。目标3专注于逆转突触 α-突触核蛋白过多通过干扰其与Hsc70伴侣蛋白的结合而引起的缺陷 有初步数据支持的想法。这些实验具有创新性，因为它们是第一个 测试确定的α-突触核蛋白分子种类对突触的影响，它们继续发展 一种新的突触模型用于这些研究，他们将测试几种新的试剂，这些试剂有可能用于 改善突触缺陷。这些实验意义重大，因为它们将阐明 过量的α-突触核蛋白导致突触缺陷的机制，它们将提供可能的 改善突触功能的有针对性的分子策略。因此，这些研究具有直接的 延缓或阻止帕金森病患者的神经退行性变、认知缺陷和痴呆 以及其他相关疾病。

The long term goal of this project is to identify the cellular and molecular mechanisms that give rise to the synaptic defects in Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and variants of Alzheimer’s disease (AD) and to develop strategies for reversing them. A pathological hallmark of these diseases is aggregation of α-synuclein throughout the neuron, including synapses. The synaptic aggregation of α-synuclein is thought to be the cause of the cognitive deficits and dementia. While it is generally agreed that α-synuclein accumulation at synapses impairs vesicle endocytosis, the underlying mechanisms remain unclear. Thus, at present, there are no known strategies for improving synaptic function in PD, DLB or AD because we don’t know the cellular or molecular targets. The proposed experiments take significant steps toward these goals by taking advantage of two classical vertebrate synapses that are ideally suited for studies on synaptic vesicle trafficking and by using both acute and genetic perturbations of α-synuclein. The approach includes a combination of quantitative biochemical, electrophysiological, and imaging assays. One model for α-synuclein toxicity suggests that it is initiated by formation of abnormal oligomers, while another proposes that build up of monomers is the trigger. Aim 1 will test predictions of both models at synapses by identifying how defined molecular species of α-synuclein (monomers, dimers, higher molecular weight oligomers) affect vesicle trafficking and neurotransmission and the underlying mechanisms. Preliminary studies indicate that monomers and dimers produce distinct effects. Experiments in Aim 2 will determine the role for α- synuclein self-association in producing synaptic defects by testing reagents that interfere with this process, including a drug with potential therapeutic value. Aim 3 is focused on reversing the synaptic defects caused by excess α-synuclein by perturbing its association with Hsc70 chaperone protein, an idea that is supported by preliminary data. The experiments are innovative because they are the first to test the effects of defined molecular species of α-synuclein at synapses, they continue the development of a new model synapse for these studies, and they will test several new reagents with potential for ameliorating the synaptic defects. The experiments are significant because they will elucidate the mechanisms by which excess α-synuclein causes synaptic deficits, and they will provide possible targeted, molecular strategies for improving synaptic function. Thus, these studies have direct implications for slowing or halting the neurodegeneration, cognitive deficits, and dementia in PD, DLB and other related diseases.