Mechanisms of Vesicle Priming and Short-Term Plasticity

描述(申请人提供)：在从突触前释放钙依赖的神经递质之前，囊泡必须通过交通到达活动区，并处于融合能力状态。囊泡启动是决定突触传递效率和可塑性的关键过程之一。囊泡启动步骤的中心是由Synaxin 1、SNAP-25和Synaptobrevin组成的突触三聚体SNARE蛋白复合体的受控组装。Synaxin 1是唯一一种含有调节性自身抑制结构域的突触SNARE蛋白，人们认为在SNARE组装进行之前，封闭的自身抑制构象必须被打开。基本启动因子Munc13-1和Munc13-2的假定功能是催化这种构象变化。此外，Munc13亚型可能会动态调节小泡的启动，以响应突触前的活动。Munc13-1依赖的突触在动作电位序列中被抑制，而Munc13-2依赖的突触增强。这一建议的目的是通过研究锁定在开放构象中的内源性Synaxin 1蛋白的突变表达的小鼠神经元的突触传递，从功能上分析构象开关在Synaxin 1中的作用。其次，我们通过系统分析Munc13结构域在囊泡启动中的作用，采用功能获得性挽救的方法，分析了Munc13功能的分子机制。最后，我们将分析Munc13亚型如何调节个体突触的短期可塑性，以及Munc13依赖的抑制和增强如何控制中枢神经系统中的信息流和突触可塑性。对参与囊泡启动的两个关键分子的分子描述将有助于设计治疗药物来操纵突触前功能的有效性和可塑性。此外，对神经递质释放机制的详细了解对于理解民族学和治疗神经疾病至关重要。

DESCRIPTION (provided by applicant): Before Ca 2+ dependent neurotransmitter release from the presynapse can be achieved, vesicle have to traffic to the active zone and prime to a fusion competent state. Vesicle priming is 1 of the key processes determining the efficiency of the synaptic transmission and plasticity. Central to the vesicle priming step is the controlled assembly of the synaptic trimeric SNARE protein complex consisting of Syntaxin 1, SNAP-25 and Synaptobrevin. Syntaxin 1 is the only synaptic SNARE protein that contains a regulatory, putative autoinhibitory domain, and it is thought that the closed, autoinhibitory conformation has to be opened before SNARE assembly can proceed. The putative function of the essential priming factors Munc13-1 and -2 is to catalyze this conformational change. In addition, Munc13 isoforms may dynamically regulate vesicle priming in response to presynaptic activity. Munc13-1 dependent synapses depress during trains of action potential, and Munc13-2 dependent synapses augment. The aims of this proposal is to functionally analyze the role of the conformational switch in Syntaxin 1 by studying synaptic transmission from murine neurons that express a mutation in the endogenous Syntaxin 1 protein locked in the open conformation. Second, we aim to analyze the molecular mechanism of Munc13 function by systematic analysis of the role of Munc13 domains in vesicle priming using a gain of function rescue approach. We will finally analyze how Munc13 isoforms regulate short-term plasticity in individual synapses, and how Munc13 dependent depression and augmentation control information flow and synaptic plasticity in the central nervous system. A molecular description of the the 2 key molecules involved in vesicle priming will aid the design of therapeutic drugs manipulating the efficacy and plasticity of presynaptic function. Moreover, a detailed knowledge of the mechanisms of neurotransmitter release is critical for the understanding of ethnology and treatment of neurological diseases.