同卵双生子单发精神分裂症miRNA表达异常及其介导的基因表达调控机制研究

Schizophrenia (SZ) is complex psychiatric disorder as results of interactions between genetic predisposition and environmental factors. Despite the apparently high heritability of SZ, there is considerable discordance within monozygotic (MZ) twin pairs, implicating a role for nongenetic, presumably environmental factors in the etiology of SZ. As an important epigenetic mechanisms, miRNAs have been revealed to be a prevalent mode of post-transcriptional regulation of gene expression. miRNAs are small regulatory RNAs that individually regulate up to several hundred genes, and collectively may regulate as much as two-thirds of the transcriptome. However, the role of miRNA in the etiological development of monozygotic twins discordant for SZ remains unclear. Based on the preliminary data of differential expressed miRNAs in peripheral blood within 2 monozygotic twins discordant for SZ determined with high-throughput next generation sequencing, the current proposal will further analyze more than 20 pairs including monozygotic twins discordant for SZ, as well as monozygotic twins concordant for SZ and for health as controls to identify the differentially expressed miRNAs. The proposal will predict the targets of differentially expressed miRNAs, and investigate the key molecular regulation network and functional enrichment between those targets based on the available database. The proposal will further use cell model to validate the regulation mechanism of disease-associated miRNAs on expression of the target genes or their downstream pathway genes. The success of this proposal will reveal the effect of miRNAs dysregulation on gene expression in the etiology of monozygotic twins discordant for schizophrenia and provide the new potential biomarkers for diagnosis and therapy of SZ.

精神分裂症（SZ）是遗传与环境相互作用所致的复杂性精神疾病。同卵双生子发病不一致性表明表观遗传改变是SZ发生的重要机制。作为重要的表观遗传学调控手段，miRNA表达失调在同卵双生子单发SZ发生过程中的作用机制还不得而知。为研究这一科学问题，我们在对2对SZ单发病同卵双生子血液样本的miRNA进行高通量测序并发现差异表达miRNAs的基础上，拟对更多的同卵双生子样本进行测序（包括单发、双发和健康对照），利用已搭建好的生物信息分析平台，鉴定SZ单发病同卵双生子中差异表达的miRNAs；对候选miRNAs进行靶基因预测、功能富集分析、并结合代谢及蛋白相互作用网络信息，阐明miRNAs表达异常对基因表达调控的影响，探究其在SZ发生过程中的作用机制；并利用细胞模型对miRNAs及其调控的靶基因进行功能验证。项目的成功实施，将揭示miRNAs在SZ发病过程中的作用机制，并为SZ的治疗提供新的药物靶标。

本项目通过对18对同卵双生子外周血样本进行高通量miRNAs测序和生物信息学分析，发现在精神分裂症单发病同卵双生子中miR-501-3p表达异常；通过双荧光素酶报告系统和miRNA对靶基因內源性表达的细胞实验，证实miR-501-3p对靶基因STX6的调控作用。考虑到STX6参与囊泡的运输，且有报道STX6和轴突发育有关，因此我们首次提出“miR-501-3p的低表达导致STX6的表达升高可能与精神分裂症有关”这一假说。为证实这一假设，我们通过siRNA干扰和CRISPR/Cas9基因敲除技术，进一步在小鼠中研究miR-501-3p对STX6的调控及其病理作用。我们发现过表达STX6或敲降miR-501-3p，小鼠的感觉运动门控功能都显著受损，出现精神分裂症样的行为学表型；并且MIR501敲除小鼠PPI受损、突触前囊泡释放异常。后续相关研究还在进行之中。本项目对于揭示miRNAs在精神分裂症发病（特别是同卵双生子单发病）过程中的作用机制提供比较全新的认识，并为精神分裂症的治疗提供新的药物靶标。