树突棘是兴奋性突触存在的部位，突触功能紊乱是神经发育紊乱的核心症状。人类遗传学研究表明，DIP2A是孤独症等神经发育紊乱的候选易感基因之一，其在神经系统的作用不明确。我们前期工作发现，Dip2a基因敲除鼠锥体神经元树突棘密度升高，神经元自发释放的幅值降低，提示Dip2a基因缺陷与兴奋性突触功能紊乱存在相关性。本立项进一步构建了Dip2a条件性基因敲除鼠，在此基础上深入研究DIP2A蛋白在树突棘形态发育和修剪中的关键作用。利用电生理技术阐明DIP2A在神经递质释放、突触连接建立中的作用环节。结合光遗传手段和动物行为学测试，研究DIP2A遗传突变对动物行为可能产生的影响并解析相关神经环路。通过蛋白质相互作用分析，发现并证实DIP2A结合突触后支架蛋白SHANK3和骨架结合蛋白，调节树突棘动态变化，从而参与维持兴奋性突触功能稳定。这些结果将为阐明神经发育紊乱机制并开展预防干预提供科学依据。

Dendritic spines are the sites of excitatory synapses. Synaptic dysfunction is a core phenotype for neurodevelopmental disorders. Human genetic studies have shown that Dip2a is one of risk genes for several neurodevelopmental disorders including autism. However, its role in the central nervous system is unclear. Our previous work found that density of dendritic spines of pyramidal neurons was increased in Dip2a knockout mice. Meanwhile the amplitude of spontaneous release of pyramidal neurons was reduced. These data highly suggested that Dip2a gene deficiency has a certain correlation with synaptic dysfunction. In this grant, we propose to construct a Dip2a conditional knockout mice model, and further study the critical roles of DIP2A in dendritic spines morphogenesis and pruning. Electrophysiological techniques will be used to investigate the impact of DIP2A on neurotransmitters release and synaptic connections. Combined optogenetic studies and animal behavior tests will be applied to examine how Dip2a genetic deficiency leads to abnormal animal behaviors. Finally, DIP2A interacted protein will be identified by mass spectrum analysis and confirmed with corresponding biochemical assays. The proposed studies may reveal the key interacting domain of DIP2A with SHANK3 and other postsynaptic proteins, and provide new evidence on how DIP2A regulates spines dynamics to maintain excitatory synaptic functions. These results will help to understand the mechanisms of neurodevelopmental disorders, and provide new therapeutic targets to diagnose and prevent neurodevelopmental disorders.