Pathophysiologic roles of alpha-synuclein at the synapse

项目摘要/摘要 这项建议的总体目标是阐明路易体(Lb)背后的机械性病理生物学事件 痴呆症-一种伴有认知障碍的痴呆症，影响着100多万美国人。一个 在LB型痴呆中已确立的分子参与者是小突触前蛋白α-突触核蛋白。在一大堆 有牵连的证据，基因组倍增和α-突触核蛋白的突变在携带这些基因的家族中被看到。 疾病；长期以来，人们已经认识到，理解导致α-突触核蛋白- LB型痴呆的介导性毒性是至关重要的。十多年来，该领域的主要关注点是 我一直在破译α-突触核蛋白的正常功能，最终目的是理解向 病理状态。然而，尽管付出了相当大的努力，但正常功能背后的确切机制 α-突触核蛋白和导致病理性聚集的早期触发因素仍然难以捉摸。我们的建议的基础是 一系列的试验性实验，在这些实验中，我们发现了α-突触核蛋白的两个功能伙伴的新角色，我们 假设这些关联中的异常是LB型痴呆的最初病理触发因素。上一首 我们和其他人的工作帮助形成了一种共识，即α-突触核蛋白是一种生理衰减器 神经递质释放，尽管潜在的机制事件尚不清楚。在之前的这些研究中，我们 提出了一种模型，其中α-SYN组织成生理上拴住突触小泡的更高阶多聚体 (SVS)-导致SV动员、SV循环减少，从而导致神经递质释放减少。在……里面 在新的先导实验中，我们发现了另外两种突触前蛋白-VAMP2和突触素-in的新角色 帮助α-突触核蛋白减弱神经传递。最终，我们的数据引导我们找到了一个工作模型，在这个模型中突触蛋白 和VAMP2在执行α-突触核蛋白功能中起顺序作用。这一模式的原则将在AIMS中得到检验 1/2.此外，该领域的一个新兴想法是，生理联系的破坏可能会导致自由的α- 突触核蛋白单体到聚集--触发病理--这可能是最早的病理之一 疾病中的事件；然而，体内证据不足。利用我们在功能性α-突触核蛋白方面的发现 合作伙伴，AIMS 2/3将询问这些联系的中断是否也会加速细胞和 LB型痴呆动物模型的建立。我们的目标是：目标1：确定VAMP2在α-突触核蛋白介导中的作用 突触衰减。目的#2：确定突触素在α-突触核蛋白介导的突触衰减和 病理学。目的#3：测试破坏生理联系可触发α-突触核蛋白的假说 活体病理学。完成后，我们的研究将揭示α-突触核蛋白的正常功能的重要线索， 以及在这些毁灭性疾病中引发痴呆症和认知障碍的事件。

PROJECT SUMMARY/ABSTRACT The overall goal of this proposal is to clarify mechanistic pathobiological events underlying Lewy body (LB) dementias – a dementing illness with cognitive impairment that affects more than a million Americans. An established molecular player in LB dementia is the small presynaptic protein α-synuclein. Amongst a plethora of incriminating evidence, genomic multiplications and mutations of α-synuclein are seen in families harboring these diseases; and it has been long recognized that understanding the mechanistic events that lead to α-synuclein- mediated toxicity in LB dementia is of utmost importance. For over a decade, a primary focus in the field has been to decipher the normal function of α-synuclein, with the ultimate goal of understanding transition to pathologic states. However, despite considerable effort, the precise mechanisms underlying the normal function of α-synuclein, and early triggers leading to pathologic aggregation remain elusive. The basis of our proposal is a series of pilot experiments, where we uncovered novel roles for two functional partners of α-synuclein, and we hypothesize that abnormalities in these associations are the initial pathologic triggers for LB dementias. Previous work from us and others has helped shape a consensus that α-synuclein is a physiologic attenuator of neurotransmitter release, though underlying mechanistic events are unclear. In these previous studies, we proposed a model where α-syn organizes into higher-order multimers that physiologically tether synaptic vesicles (SVs) – leading to a diminution in SV-mobilization, SV-recycling, and consequently, neurotransmitter release. In new pilot experiments, we discovered novel roles for two other presynaptic proteins – VAMP2 and synapsin – in helping α-synuclein attenuate neurotransmission. Eventually, our data led us to a working model where synapsin and VAMP2 play sequential roles in executing α-synuclein function. Tenets of this model will be tested in Aims 1/2. Additionally, an emerging idea in the field is that disruption of physiologic associations might allow free α- synuclein monomers to aggregate – triggering pathology – and that this might be one of the earliest pathologic events in disease; however, in vivo evidence is lacking. Leveraging our discoveries on functional α-synuclein partners, Aims 2/3 will ask if a disruption of these associations might also accelerate pathology in cellular and animal models of LB dementias. Our aims are: Aim #1: Identify the role of VAMP2 in α-synuclein mediated synaptic attenuation. Aim #2: Identify the role of synapsin in α-synuclein mediated synaptic attenuation and pathology. Aim #3: Test the hypothesis that disrupting physiologic associations can trigger α-synuclein pathology in vivo. Upon completion, our studies should reveal vital clues into the normal function of α-synuclein, as well as events that trigger dementia and cognitive impairment in these devastating illnesses.