Analysis of Ca2+ -Triggered Neurotransmitter Release

Ca2 触发神经递质释放的分析

• 批准号: 6967013
• 负责人: CHRISTIAN ROSENMUND
• 金额: $ 31.22万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6967013
• 关键词: calcium ion; electrophysiology; genetically modified animals; laboratory mouse; nerve /myelin protein; neurotransmitter transport; protein structure function; synapses; synaptic vesicles; synaptotagmin

DESCRIPTION (provided by applicant): Efficient and rapid transduction mechanisms at synapses are required for coherent oscillations and synchronization of activity of brain circuits. The presynapse transduces within <1 ms action potentials into a Ca2+-triggered synchronous fusion of neurotransmitter containing vesicles. Two protein families, the Complexins and Synaptotagmins, are key players in tuning the generic SNARE protein-based membrane fusion apparatus into a high speed transducer. Both proteins are known to interact with the SNARE complex. The goal of this study is to understand how these proteins accomplish fast fusion, and to determine which interactions are relevant for their function. We hypothesize that Complexin and Synaptotagmin 1 act by reducing the energy barrier of the fusion reaction, but they accomplish this using different molecular mechanisms. Following binding to the SNARE complex, Complexins seem to cause stabilization of a profusion complex, or alternatively, serve as an adaptor to enable Synaptotagmin 1 binding to the SNARE complex. Synaptotagmin 1 may trigger fast neurotransmitter release by Ca2+-dependent binding of its C2A and C2B domains to the plasma membrane, and this membrane penetration determines fusion rates by destabilizing the profusion membrane complex. To decipher the function of Complexin and Synaptotagmin, we propose an integrated approach using electrophysiological, structural, and biochemical experiments. First, we will analyze synaptic properties in neurons derived from Complexin 1/2/Synaptotagmin 1 knockout mice. We will then explore the structure-function relationship of protein domains that are putatively involved in synchronous release using a rescue approach. Finally, we will probe whether both proteins act independently or in conjunction with each other, and whether they act sequentially. A better understanding of the mechanism of synchronous release may help to find the cause and treatment of diseases that show disturbed oscillations and synchronization patterns in brain circuits, like Attention Deficit Syndrome, Autism, Huntingdon's Disease or Schizophrenia.

描述（由申请人提供）： 脑回路活动的相干振荡和同步需要突触处高效且快速的转导机制。突触前在 <1 毫秒内将动作电位转变成 Ca2+ 触发的包含神经递质的囊泡的同步融合。复合蛋白和突触结合蛋白这两个蛋白质家族是将基于 SNARE 蛋白质的通用膜融合装置调整为高速传感器的关键因素。已知这两种蛋白质都会与 SNARE 复合体相互作用。这项研究的目的是了解这些蛋白质如何实现快速融合，并确定哪些相互作用与其功能相关。我们假设 Complexin 和 Synaptotagmin 1 通过降低融合反应的能垒起作用，但它们使用不同的分子机制来实现这一点。与 SNARE 复合物结合后，Complexins 似乎会导致丰富复合物的稳定，或者充当接头，使 Synaptotagmin 1 能够与 SNARE 复合物结合。突触结合蛋白 1 可能通过其 C2A 和 C2B 结构域与质膜的 Ca2+ 依赖性结合来触发神经递质的快速释放，并且这种膜渗透通过破坏丰富的膜复合物的稳定性来决定融合率。为了破译复合蛋白和突触结合蛋白的功能，我们提出了一种利用电生理学、结构和生化实验的综合方法。首先，我们将分析来自 Complexin 1/2/Synaptotagmin 1 敲除小鼠的神经元的突触特性。然后，我们将使用救援方法探索推测参与同步释放的蛋白质结构域的结构-功能关系。最后，我们将探讨这两种蛋白质是独立作用还是相互结合作用，以及它们是否顺序作用。更好地了解同步释放机制可能有助于找到大脑回路振荡和同步模式紊乱的疾病的原因和治疗方法，例如注意力缺陷综合症、自闭症、亨廷顿舞蹈症或精神分裂症。