Role of VAMP1 in synaptic transmission and Alzheimer's dementia

摘要 阿尔茨海默病（Alzheimer's disease，AD）是导致痴呆的主要原因之一，在我国的老龄化进程中影响着数以百万计的老年患者 因此，这是一个严峻的卫生保健挑战。目前可用的药物可以提供一些 暂时缓解，但没有一种能够阻止疾病进展或治愈。为了开发更好的治疗方法， 迫切需要对疾病病因有清楚的认识。最近的数据表明， 囊泡内吞作用的活性，特别是速率对于淀粉样蛋白前体的加工至关重要 淀粉样蛋白（Abeta）是AD中主要毒性成分的来源。的确切分子 连接突触传递和APP处理的机制仍然未知。我的实验室是长期 目标是在大脑中确定新的分子治疗靶点，以帮助预防突触功能障碍 和神经退化来保护认知和记忆。本申请的目的是检查 特定类别的蛋白质-囊泡膜相关蛋白（VAMP/突触小泡蛋白）及其作用 突触释放和Abeta的产生。我们强有力的初步结果确立了突触小泡蛋白1/VAMP 1 （syb 1），SNARE（SNAP受体）复合物的成员，作为这项创新研究的新对象， 痴呆：a）在人类遗传学中筛选VAMP 1基因的单核苷酸多态性（SNP）变体 编码syb 1的SNP与晚发性AD显著相关; B）与表达增加相关的SNP 与VAMP 1低表达相关的SNPs可降低AD的风险; c）在新的VAMP 1 KO小鼠中，内源性A β 40和A β 42水平显著降低。基于 根据这些观察，中心假设是VAMP 1是囊泡释放之间的关键偶联蛋白， APP处理。我们假设VAMP 1水平的变化改变了突触的耦合， 传递到APP加工，因此对Abeta产生有深远的影响。的理由 一项拟议的研究是，了解激活Abeta产生的分子机制将提供 一种新的，更好的降低Abeta水平的方法，它可以预防或延缓AD患者的认知能力下降。我们将 通过追求三个具体目标来验证这一假设：1）检查突触泡蛋白表达水平对 使用新型VAMP 1 KO小鼠在神经元中的突触活性和Abeta产生。2)识别结构 VAMP 1的元件将突触活性与APP加工的淀粉样蛋白生成途径偶联。3)评价 降低的VAMP 1水平对预防AD模型Tg 2576小鼠体内认知损害的作用。 这些目标将通过对突触活动、内吞作用和Abeta产生的广泛分析进行测试 通过复杂的方法，包括多电极和膜片钳电生理学和活体荧光 显微镜这项研究意义重大，因为它有可能将VAMP 1确定为第一个 淀粉样蛋白生成突触调节剂以及AD诊断和治疗的新靶点。

Abstract Alzheimer’s disease (AD) is a major cause of dementia, affecting millions of elderly patients in our aging society, and thus represents a severe health care challenge. Currently available drugs may provide some temporary relief but none of them is able to halt disease progression or cure. To develop better therapies a clear understanding of the disease etiology is urgently needed. Recent data suggest the rate of synaptic activity and particularly rate of vesicle endocytosis is critically important for the processing of amyloid precursor protein (APP) into beta-amyloid (Abeta), a source of major toxic component in AD. The exact molecular mechanism connecting synaptic transmission to APP processing is still unknown. My laboratory’s long-term goal is to identify new, molecular therapeutic target(s) in the brain that can help to prevent synaptic dysfunction and neurodegeneration to preserve cognition and memory. The objective in this application is to examine a specific class of proteins – the vesicular membrane associated proteins (VAMPs/synaptobrevins) and their role in synaptic release and Abeta production. Our strong preliminary results establish synaptobrevin1/VAMP1 (syb1), a member of the SNARE (SNAP Receptor) complex, as a novel object for this innovative research of dementia: a) in human genetic screens single nucleotide polymorphism (SNP) variants of the VAMP1 gene encoding syb1 are significantly associated with late onset AD; b) SNPs associated with increased expression of VAMP1 increase the risk of AD and SNPs associated with lower VAMP1 expression reduces the risk of AD; c) in the new VAMP1 KO mice endogenous Abeta40 and Abeta42 levels are substantially reduced. Based on these observations, the central hypothesis is that VAMP1 is a key coupling protein between vesicular release and APP processing. We hypothesize that variations in VAMP1 level alter the coupling of synaptic transmission to APP processing and therefore have profound effect on Abeta production. The rationale for the proposed research is that understanding the molecular mechanism that activates Abeta production will provide a novel, better way to lower Abeta levels and it may prevent or delay cognitive decline in AD patients. We will test this hypothesis by pursuing three specific aims: 1) Examine the effect of synaptobrevin expression level on synaptic activity and Abeta production in neurons using the novel VAMP1 KO mice. 2) Identify the structural elements of VAMP1 coupling synaptic activity to amyloidogenic pathway of APP processing. 3) Evaluate the effects of reduced VAMP1 levels on preventing cognitive impairment in the AD model Tg2576 mice in vivo. These aims will be tested through extensive analysis of synaptic activity, endocytosis and Abeta production with sophisticated methods including multi-electrode and patch-clamp electrophysiology and live fluorescence microscopy. The proposed research is significant because it has the potential to identify VAMP1 as the first synaptic regulator of amyloidogenesis and novel target for AD diagnosis and therapy.