Pathophysiologic roles of alpha-synuclein at the synapse

α-突触核蛋白在突触中的病理生理作用

• 批准号: 10617745
• 负责人: Subhojit Roy
• 金额: $ 44.85万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-15 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10617745
• 关键词: Acceleration; Advocate; Affect; Alanine; Alzheimer' s Disease; American; Animal Model; Area; Attenuated; Binding; Biological Assay; Cell model; Consensus; Data; Dementia; Dementia with Lewy Bodies; Disease; Event; Family; Genomics; Goals; Impaired cognition; Knowledge; Lewy Body Dementia; Maps; Mediating; Microscopy; Modeling; Molecular; Mutagenesis; Mutation; Neocortex; Nerve Degeneration; Neurons; Optics; PHluorin; Pathologic; Pathology; Physiological; Play; Process; Proteins; Recycling; Reporting; Research Personnel; Role; Series; Shapes; Synapses; Synapsins; Synaptic Vesicles; System; Testing; Toxic effect; Vesicle; Work; alpha synuclein; attenuation; demented; experimental study; in vivo; in vivo evaluation; monomer; mutant; neocortical; neurotransmission; neurotransmitter release; novel; predictive modeling; presynaptic; synucleinopathy; tool; trafficking

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.

该提案的总体目标是阐明路易体 (LB) 痴呆症的机制病理生物学事件，路易体痴呆症是一种伴有认知障碍的痴呆症，影响超过一百万美国人。 LB 痴呆中一个已确定的分子参与者是小突触前蛋白 α-突触核蛋白。在大量的罪证中，在携带这些疾病的家庭中发现了基因组增殖和 α-突触核蛋白突变；人们早就认识到，了解导致 LB 痴呆中 α-突触核蛋白介导的毒性的机制事件至关重要。十多年来，该领域的主要焦点一直是破译 α-突触核蛋白的正常功能，最终目标是了解向病理状态的转变。 然而，尽管付出了相当大的努力，α-突触核蛋白正常功能的精确机制以及导致病理聚集的早期触发因素仍然难以捉摸。我们提议的基础是一系列试点实验，其中我们发现了 α-突触核蛋白的两个功能伙伴的新作用，并且我们假设这些关联的异常是 LB 痴呆的最初病理触发因素。我们和其他人之前的工作帮助达成了共识，即 α-突触核蛋白是神经递质释放的生理衰减剂，尽管潜在的机制事件尚不清楚。在之前的这些研究中，我们提出了一个模型，其中 α-syn 组织成高阶多聚体，在生理上束缚突触小泡 (SV)，从而导致 SV 动员、SV 循环减少，从而减少神经递质释放。在新的试点实验中，我们发现了另外两种突触前蛋白（VAMP2 和突触蛋白）在帮助 α-突触核蛋白减弱神经传递方面的新作用。最终，我们的数据引导我们建立了一个工作模型，其中突触蛋白和 VAMP2 在执行 α-突触核蛋白功能中发挥连续作用。该模型的原则将在目标 1/2 中进行测试。此外，该领域的一个新兴想法是，生理关联的破坏可能会使游离的 α-突触核蛋白单体聚集，从而引发病理学，这可能是疾病中最早的病理事件之一；然而，缺乏体内证据。利用我们对功能性 α-突触核蛋白伙伴的发现，Aims 2/3 将询问这些关联的破坏是否也可能加速 LB 痴呆细胞和动物模型的病理学发展。我们的目标是： 目标#1：确定 VAMP2 在 α-突触核蛋白介导的突触衰减中的作用。目标#2：确定突触蛋白在 α-突触核蛋白介导的突触衰减和病理学中的作用。目标#3：检验破坏生理关联可以在体内引发 α-突触核蛋白病理学的假设。完成后，我们的研究应该揭示 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。