脆性X综合征（FXS）是临床最常见的遗传性智力残疾和自闭症诱因，主要是由于FMR1基因5'非翻译区CGG重复序列扩增引起FMRP表达缺失导致，但具体发病机制不明，也尚无有效治疗方法，因此探寻FXS的发病机制及治疗途径是社会和临床都亟待解决的难题。在延续大量前期工作基础上，本项目拟通过逆转录病毒介导的转染系统建立FXS-iPSC模型，应用CRISPR/Cas9技术靶向编辑FXS-iPSC中FMR1基因CGG重复序列以逆转FMR1基因沉默，并在细胞和整体水平鉴定FMR1表达激活后对FXS神经元的拯救；同时运用RNA-seq、ChIP-seq及BSP法等研究FMR1从基因沉默到表达激活中的表观遗传变化。本项目旨在建立实用性的FMR1基因表达修复平台，发现FMR1激活途径中的核心调控分子，为临床研究和治疗FXS提供药物靶位和新的治疗途径，为三核苷酸重复疾病的基因和细胞治疗提供一种研究策略。

Fragile X syndrome (FXS) is the most common clinical cause of hereditary mental disability and autism, mainly results from the amplification of CGG repeats in the 5'-UTR of fragile X mental retardation 1 (FMR1) gene and thereby loss of fragile X mental retardation protein(FMRP) expression. However, the specific pathogenesis of FXS is still unclear and there is no effective treatment. Therefore, exploring the pathogenesis and therapeutic approach of FXS is an important social and clinical problem. To proceed this study on the basis of the obtained data in our previous work, we will generate FXS-specific induced pluripotent stem cell(iPSC) model through retroviral mediated transgene technique, apply CRISPR/Cas9 gene editing technique to edit the CGG repeats of FMR1 gene in the FXS-iPSC in order to reverse FMR1 gene silencing, and identify the recovery of FXS neurons after FMR1 expression activation at both cellular and global levels. Meanwhile, apply RNA-seq、ChIP-seq and Bisulfite sequencing PCR techniques to study the epigenetic variation from FMR1 gene silencing to expression activation. We aim to establish the practical FMR1 expression repairing platform, discover the core regulators in the FMR1 gene activation pathway, provide drug targets and new therapeutic approaches for the clinical therapy of FXS, and provide a research strategy for gene and cell therapy trinucleotide repeat diseases.