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自发神经递质释放调节的分子机制。突触处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，其中自发微型电位（minis）主要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，自发释放的频率受到活动的调节，并且可以驱动突触结构修饰和生长，这些变化导致神经元连接的长期改变。自发释放的调节可能会直接影响分子“融合钳”，该分子“融合钳”防止在缺乏钙的情况下引发的囊泡与突触前膜融合。复合蛋白已被鉴定为调节果蝇神经肌肉接头（NMJ）处的自发释放的囊泡融合钳。然而，复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，以确定复合蛋白调节自发神经递质释放的分子机制。目的1将研究作为囊泡融合钳的复合蛋白功能的进化保守性。目的2将定义介导复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利用果蝇和体内电生理记录中可用的遗传工具，以及体外生物化学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氏病在内的许多神经疾病中已经报道了复合蛋白水平的改变，这表明复合蛋白功能障碍和自发释放的异常速率可能导致几种人类神经病理学。神经递质释放的缺陷与许多神经系统疾病有关，包括精神分裂症、亨廷顿病和阿尔茨海默病。了解神经递质释放的分子机制，将提供潜在的新的目标和见解如何改变自发释放有助于神经系统疾病。

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.