LncRNA-XIST对神经元miR-132通路的调控作用及其在阿尔茨海默病中的影响

Alzheimer's Disease (AD) is a complex neurodegenerative disorder that affects one in ten individuals over 65. The number of affected people, and the corresponding costs to society, are predicted to double within 20 years. Meta-analysis of global epidemiological studies indicates that in most regions female's AD prevalence is higher than male's in every age group, with the highest statistical significance in Asia-Pacific. XIST is a non-coding RNA only expressed in female, with a high abundance in neurons. Recent studies have shown that XIST can bind miRNAs as a sponge to regulate tumor progression, but its brain functions are unknown. Preliminary CLIP-Seq experimental data suggests that XIST has several strong binding sites for miR-132, which is one of the most important miRNAs in neurons. Many studies from various aspects have indicated miR-132's function as a neuroprotector. This proposal aims to validate the interaction between XIST and miR-132 in primary neurons, and to testify whether such interaction sponges miR-132 and affects neuronal health and vulnerability to disease toxins. Mechanically, we will utilize interactome, transcriptome and RNAi technologies to identify the most important miR-132 targets affected by XIST, and thus establish the "XIST/miR-132/key mRNAs/neuronal health" axis in neurons. The proposed project may significantly expand our views of mechanisms underlying the gender gap in AD, as well as the repertoire of novel targets for the disease.

阿尔茨海默病（AD）是一种在老年人群中常见的神经退行性疾病。WHO数据显示女性患病率在各个地区都高于同一年龄段的男性。XIST是一种仅在女性表达的非编码RNA，并在神经元内丰度很高。近期研究显示，XIST可以结合miRNA并形成海绵效应，进而影响肿瘤进展，但其在神经系统的作用还没有报道。初步的CLIP-Seq数据显示XIST存在多个miR-132的强结合位点。miR-132是神经元内最重要的miRNA之一，已被广泛证实具有神经保护功能。本研究将验证XIST与miR-132在原代神经元内的相互作用，以及其是否通过海绵效应阻止miR-132的功能来对神经元造成损伤或者削弱其神经毒素抵抗力。从分子机制角度，本研究将探索受XIST影响的miR-132关键靶标mRNA，从而建立“XIST/miR-132/关键靶标/神经活力”这一调控通路，为AD的性别不平衡提供新角度的解释，并为治疗AD提供潜在靶点。

阿尔茨海默病（AD）是一种致命的神经退行性疾病，影响约十分之一的65岁以上老年人群。世界多个地区流行病学调查的荟萃分析显示，女性患病率在各个地区都高于同一年龄段的男性，但是该性别不平衡的原因并未研究清楚。XIST是一种由X染色体指导转录的长非编码RNA（lncRNA），仅在女性的细胞中表达，并且在神经元内表达水平很高。本项目建立了性别特异的小鼠原代神经元培养方法，利用CLEAR-CLIP技术在雌性原代神经元内发现XIST与重要的神经保护性分子miR-132-3p存在配对结合。miR-132-3p的交互作用组在雌性和雄性小鼠原代神经元内也存在区别，提示性别特异的XIST与miR-132-3p的结合可能通过影响其对下游靶标mRNA的结合和调控而贡献AD的性别不平衡。利用RNA干扰技术在雌性小鼠原代神经元内敲降XIST可以在不改变miR-132-3p表达丰度的前提下降低miR-132-3p靶标GSK3β的表达，支持了高丰度XIST通过海绵吸附影响miRNA可及性和下游调控功能的分子机制假说。雌性和雄性小鼠原代神经元对谷氨酸神经毒性的耐受性存在差异，且在雌性小鼠原代神经元内敲降XIST可以在一定程度上提升对谷氨酸的耐受性。本项目发现的“XIST/miR-132-3p/GSK3β/神经健康程度”通路首次揭示XIST在中枢神经系统可以调控miRNA的功能，并为AD的性别不平衡提供一个全新的分子假说。本项目还利用人源诱导多能干细胞分化的神经元结合高通量筛选和高通量测序方法，探索了可以诱导提升miR-132-3p表达的小分子化合物，为阿尔茨海默病和其他神经退行性疾病提供新的候选治疗药物。