Analysis of Ca2+ -Triggered Neurotransmitter Release

Ca2 触发神经递质释放的分析

• 批准号: 7072241
• 负责人: CHRISTIAN ROSENMUND
• 金额: $ 30.49万
• 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 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7072241
• 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）：突触处的有效和快速的转导机制是脑回路的活动的相干振荡和同步所必需的。突触前体在<1 ms的动作电位内将神经递质转导为含有囊泡的Ca 2+触发的同步融合。两个蛋白质家族，复合蛋白和突触结合蛋白，是将通用的基于SNARE蛋白的膜融合装置调谐成高速换能器的关键参与者。已知这两种蛋白质都与SNARE复合物相互作用。本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。我们假设复合蛋白和突触结合蛋白1通过降低融合反应的能垒来发挥作用，但它们使用不同的分子机制来实现这一目标。在与SNARE复合物结合后，复合蛋白似乎引起丰富复合物的稳定化，或者可替代地，充当使突触结合蛋白1能够与SNARE复合物结合的衔接子。突触结合蛋白1可以通过其C2 A和C2B结构域与质膜的Ca 2+依赖性结合来触发快速神经递质释放，并且这种膜穿透通过使profusion膜复合物不稳定来确定融合速率。为了破译复杂蛋白和突触结合蛋白的功能，我们提出了一个综合的方法，使用电生理，结构和生化实验。首先，我们将分析来自Complexin 1/2/Synaptotagmin 1敲除小鼠的神经元中的突触特性。然后，我们将探索结构-功能关系的蛋白质结构域参与同步释放使用救援方法。最后，我们将探讨这两种蛋白质是独立作用还是相互作用，以及它们是否顺序作用。更好地了解同步释放的机制可能有助于找到大脑回路中显示干扰振荡和同步模式的疾病的原因和治疗，如注意力缺陷综合征，自闭症，亨廷顿氏病或精神分裂症。