Pathophysiologic roles of alpha-synuclein at the synapse

项目总结/摘要 本提案的总体目标是阐明路易体（LB）的病理生物学机制 痴呆症--一种有认知障碍的痴呆症，影响着100多万美国人。一个 在LB痴呆中，已确定的分子参与者是小突触前蛋白α-突触核蛋白。在众多的 证据表明，基因组倍增和α-突触核蛋白的突变被认为是在家庭窝藏这些 长期以来，人们一直认为，了解导致α-突触核蛋白- 介导的毒性在LB痴呆中是最重要的。十多年来，该领域的主要焦点是 一直在破译α-突触核蛋白的正常功能，最终目标是理解过渡到 病理状态然而，尽管付出了相当大的努力，正常功能背后的确切机制 的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。我们建议的基础是 一系列的试验性实验，我们发现了α-突触核蛋白的两个功能伴侣的新作用， 假设这些关联的异常是LB痴呆的最初病理触发因素。先前 我们和其他人的工作帮助形成了一个共识，即α-突触核蛋白是一种生理衰减剂， 神经递质释放，但潜在的机制事件尚不清楚。在之前的研究中，我们 提出了一个模型，其中α-syn组织成更高阶的多聚体，在生理上束缚突触囊泡 (SVs)- 导致SV动员、SV再循环以及因此神经递质释放的减少。在 在新的试点实验中，我们发现了另外两种突触前蛋白--VAMP 2和突触蛋白--在突触形成中的新作用。 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， 和VAMP 2在执行α-synuclein功能中起着顺序性的作用。该模式的原则将在Aims中得到检验 1/2.此外，该领域的一个新兴观点是，生理协会的破坏可能会使游离α- 突触核蛋白单体聚集-触发病理-这可能是最早的病理之一 然而，缺乏体内证据。利用我们对功能性α-突触核蛋白的发现 合作伙伴，目标2/3将询问这些协会的中断是否也可能加速细胞和组织中的病理学， LB痴呆动物模型。我们的目标是：目标#1：确定VAMP 2在α-突触核蛋白介导的细胞凋亡中的作用。 突触衰减目的#2：确定突触蛋白在α-突触核蛋白介导的突触衰减中的作用， 病理目的#3：测试破坏生理关联可以触发α-突触核蛋白的假设 体内病理学完成后，我们的研究应该会揭示α-突触核蛋白正常功能的重要线索， 以及在这些毁灭性疾病中引发痴呆和认知障碍的事件。

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.