The Munc13 N-terminal region: a hub of protein interactions and regulatory signal processing in neurotransmitter release

神经递质释放速度非常快，受到高度调节，数百种蛋白质参与驱动和控制它。其中有5个大型多结构域蛋白（Aczonin/Piccolo, Bassoon, CAST/ELKS， Munc13和RIM），它们彼此之间和其他蛋白之间相互连接，并且被认为是许多突触前蛋白组织成一个有效运作的“分子机器”的重要组成部分。他们的基因被发现在几种单基因人类疾病中发生突变，似乎会导致精神分裂症、抑郁症、2型糖尿病和肌萎缩侧索硬化症（ALS）等遗传复杂疾病。为了了解这些蛋白质在神经系统正常和异常功能中的作用，我们需要揭示它们起作用的分子机制。我的实验室最近发现了一个多结构域复合体，其中所有五种蛋白质都参与其中，并且可能构成机械相互作用和调节信号处理的中心。现在，我的目标是通过以下方法进一步阐明该复合体的功能：a)生物化学（复合体其他成员的表征；结合伙伴的组合相互作用；通过差异剪接、磷酸化、Ca2+/钙调蛋白、二酰基甘油和Rab3 gtpase进行调节）；b)结构生物学（通过核磁共振和x射线晶体学测定结构域配合物的分子结构）；c)分子生物学、电生理学和细胞生物学（神经传递、突触可塑性和突触发生中个体相互作用和调节信号的选择性诱变和功能表征）。

Neurotransmitter release is very fast and highly regulated, and several hundred proteins participate in driving and controlling it. Among these are five large multidomain proteins (Aczonin/Piccolo, Bassoon, CAST/ELKS, Munc13 and RIM), which are multiply interconnected with each other and additional proteins, and which are believed to be important for the organization of the many presynaptic proteins into an efficiently functioning “molecular machine”. Their genes were found to be mutated in several monogenic human diseases, and seem to contribute to genetically complex disorders like schizophrenia, depression, type 2 diabetes and amyotrophic lateral sclerosis (ALS). To understand the roles of these proteins in the normal and abnormal functioning of the nervous system, we need to uncover the molecular mechanisms through which they act. My laboratory has recently identified a multidomain complex in which all five proteins participate and which may constitute a hub of mechanistic interplay and regulatory signal processing. Now I aim to further elucidate the functions of this complex by a combination of approaches: a) Biochemistry (characterization of additional members of the complex; combinatorial interplay of binding partners; regulation by differential splicing, phosphorylation, Ca2+/calmodulin, diacylglycerol and Rab3 GTPases); b) Structural biology (determination of the molecular structures of domain complexes by NMR and X-ray crystallography); c) Molecular biology, electrophysiology and cell biology (selective mutagenesis and functional characterization of the roles of individual interactions and regulatory signals in neurotransmission, synaptic plasticity and synaptogenesis).