Molecular mechanisms regulating spontaneous neurotransmitter release

描述（由申请人提供）：本研究计划的主要重点是确定调节自发神经递质释放的分子机制。突触中神经元通信的表征主要集中在动作电位触发的突触囊泡融合上，自发微型电位（minis）很大程度上被认为代表背景噪声。然而，自发释放的调节独立于诱发释放。此外，自发释放的频率受活动调节，可以驱动突触结构的修饰和生长，这些变化导致神经元连通性的长期改变。自发释放的调节可能直接影响分子“融合钳”，在缺乏钙的情况下，该“融合钳”可防止启动囊泡与突触前膜融合，Complexin已被确定为调节果蝇神经肌肉连接处（NMJ）自发释放的囊泡融合钳。然而，络合蛋白作为融合钳调节自发释放的分子机制尚不清楚。果蝇NMJ将被用作体内模型系统，以确定复合体蛋白调节自发神经递质释放的分子机制。目的1将检查络合蛋白功能作为囊泡融合钳的进化守恒。目的2将定义介导络合蛋白调节自发释放能力的分子机制。这两个目标都将广泛使用果蝇遗传工具和体内电生理记录，以及体外生化和免疫细胞化学方法。在包括精神分裂症、亨廷顿氏病和阿尔茨海默病在内的许多神经系统疾病中都报道了络合蛋白水平的改变，这表明络合蛋白功能障碍和自发释放率异常可能导致几种人类神经疾病。神经递质释放缺陷与许多神经系统疾病有关，包括精神分裂症、亨廷顿氏病和阿尔茨海默病。了解神经递质释放的分子机制将提供潜在的新靶点，并深入了解改变的自发释放如何导致神经系统疾病。

DESCRIPTION (provided by applicant): The main focus of this research proposal is to determine the molecular mechanisms by which spontaneous neurotransmitter release is regulated. Characterization of neuronal communication at synapses has largely focused on action potential-triggered synaptic vesicle fusion, with spontaneous miniature potentials (minis) largely thought to represent background noise. However, spontaneous release is regulated independently of evoked release. Moreover, the frequency of spontaneous release is regulated by activity and can drive synaptic structural modification and growth, changes resulting in long-lasting alterations in neuronal connectivity. Regulation of spontaneous release would likely impinge directly on the molecular "fusion clamp" which prevents primed vesicles from fusing with the presynaptic membrane in the absence of calcium, Complexin has been identified as the vesicle fusion clamp that regulates spontaneous release at the Drosophila neuromuscular junction (NMJ). However, the molecular mechanism by which complexin functions as a fusion clamp to regulate spontaneous release is unknown. The Drosophila NMJ will be used as an in vivo model system to determine the molecular mechanisms by which complexin regulates spontaneous neurotransmitter release. Aim 1 will examine evolutionary conservation of complexin function as a vesicle fusion clamp. Aim 2 will define the molecular mechanisms that mediate complexin's ability to regulate spontaneous release. Both aims will make extensive use of genetic tools available in Drosophila and in vivo electrophysiology recordings, as well as in vitro biochemical and immunocytochemical approaches. Alterations in complexin levels have been reported in a number of neurological diseases including schizophrenia, Huntington's disease, and Alzheimer's disease, suggesting the complexin dysfunction and abnormal rates of spontaneous release may contribute to several human neuropathologies. Defects in neurotransmitter release are implicated in a number of neurological diseases including schizophrenia, Huntington's disease, and Alzheimer's disease. Understanding the molecular mechanisms that underlie neurotransmitter release will provide potentially new targets and insights into how altered spontaneous release contributes to neurological diseases.