自闭症关联突触蛋白Densin-180的致病机理研究

Loss-of-function mutation of Densin-180, a LAP family member enriched at excitatory post-synaptic densities, has been linked to genetic risk of autism, yet the mechanisms are still unclear. Our previous work revealed Erbin, another LAP member with sequence and structure highly identical to Densin-180, expresses in cortical inhibitory interneurons and regulates its excitatory synaptic transmission. Our preliminary studies revealed that Densin-180 expresses in both excitatory and inhibitory neurons. Knock-down of Densin-180 in neurons disrupted synaptic structures and functional synaptic proteins, including Shank3, Erbin, δ-catenin which are Densin-180-binding proteins and implicated in autism. These synaptic proteins were affected by depletion of Densin-180 differently, suggesting Densin-180 regulates synaptic development through multiple regulative pathways on autism-associated molecular network. By incorporating approaches for molecular, cellular, circuit, and systemic exploration on primary cultures and genetically engineered mice, we propose here to investigate thoroughly the molecular mechanisms of Densin-180 on regulation of synapses and pathophysiology of autism.

富集于兴奋性突触后结构的Densin-180最近被鉴定出其基因功能缺失突变与自闭症关联，但其机制尚不明了。我们前期工作发现结构和序列与Densin-180高度同源的Erbin定位于大脑皮层中间神经元的突触后结构，特异性调控其上的兴奋性突触传递；而Densin-180既表达于兴奋性神经元，又表达于抑制性中间神经元。离体研究中发现敲低Densin-180特异性影响兴奋性突触结构和某些功能蛋白，包括Shank3、Erbin、δ-catenin等与Densin-180结合的自闭症关联分子。它们在缺少Densin-180的神经元中呈现不同的变化趋势，提示Densin-180以多种分子调节机制通过调控自闭症关联分子网络参与突触建设。本项目将结合原代培养神经元和条件性基因工程小鼠，以从分子、细胞、环路到整体的多种研究手段充分解析Densin-180调控突触的分子机制及其缺失导致自闭症病理病征的致病机理。

精神类疾病的病理病症的发生和发展是由多种神经细胞类型的病变参与的复杂过程，遗传致病因素可能引发不同种类神经元或胶质细胞的原发性病变。为了全面解析自闭症关联基因Densin的缺失性突变引发自闭症相关病理和行为异常的分子和细胞机制，我们以多种cre工具鼠构建了不同神经细胞特异性的Densin条件性敲除小鼠，发现Densin对大脑皮层兴奋性神经元的形态发育和基本突触传递功能不可或缺。通过对突触蛋白和Densin相互作用蛋白的分析，我们揭示了Densin通过稳定delta-catenin，从而维持AMPAR中GluA2亚基向突触的转运，同时稳定NMDAR的水平，并促进树突和树突棘的成熟。此外，我们初步揭示Densin可能以相同的分子机制调控抑制性神经元的功能以促进个体成长，以及调控神经活动刺激少突胶质细胞的分化发育的过程从而负向调控中枢髓鞘的发育和成熟。我们进一步以体内和体外技术相结合研究了导致星型胶质细胞和少突胶质细胞发生不同类型病变的分子调控机制，加深了对疾病病征关联的细胞特异性的原发性病理发生的分子细胞机制的认识，以提供临床诊断和干预的基础。

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