等位基因特异性DNA甲基化（ASM）参与同卵双生子单发精神分裂症发病机制的研究

Schizophrenia (SZ) is a complex heritable psychiatric disorder caused by gene-environment interactions. DNA methylation is an important epigenetic mechanism mediating the gene-environment interactions. As our previous studies found abnormal imprinting characterized by allelic transmission disequilibrium from parents to offspring and unequal allele-specific expression (ASE) of the GABA(A) receptor beta (2) subunit gene GABRB2 in SZ, the relationships between the disease-associated ASE and the allele-specific DNA methylation (ASM) in etiological development of SZ need to be examined...Based on the phenomena that the monozygotic twin pairs display identical genetic background but discordance for diagnostic phenotype (one for schizophrenia, another for health), the current proposal hypothesizes that ASM-regulated ASE mediates the involvement of gene-environment interactions in the etiologic developments of SZ. Employed with blood DNA and RNA from monozygotic twin pairs discordant for schizophrenia, and concordant for schizophrenia or for health, the proposal will perform genome-wide assays of DNA genetic variation, DNA methylation and RNA expression to systematically screen the SZ-related methylome and transcriptome profiles, and to identify the functional ASM and/or ASE loci displaying monoallelic methylation regulated monoallelic expression in the etiologic developments of SZ. The cellular and molecular mechanism of the functional ASM/ASE loci will be further analyzed in an epigenetic methionine-induced animal model of SZ and tissue-cultural cell line expressing recombinant protein, mini-gene or reporter gene containing functional ASM/ASE loci. Also the roles of ASM in regulation of ASE loci will be evaluated in large case-control cohorts.. .The current proposal will reveal the epigenetic mechanism of ASM-regulated ASE mediates the involvement of gene-environment interactions in the pathophysiology of SZ, and provide new evidences to identify novel biomarkers for in vivo monitoring the etiologic developments of SZ.

精神分裂症（SZ）是遗传与环境因素相互作用所致的复杂性遗传病。DNA甲基化是介导遗传与环境互作的重要表观遗传调控机制。我们前期发现等位基因特异性表达（ASE）介导的异常印记与SZ相关，但等位基因特异性DNA甲基化（ASM）是否参与调控尚不清楚。针对SZ单发病同卵双生子对基因型相同而表型变异的现象，本项目提出ASM调控ASE介导了遗传与环境互作参与SZ发生发展的假说，并以SZ单发病和双发病同卵双生子、健康同卵双生子为研究对象，开展基因组、甲基化组和转录组检测并整合关联分析，系统绘制与SZ相关的DNA甲基化和RNA表达差异图谱，发现表型变异相关的单等位基因甲基化调控单等位基因表达的ASM/ASE基因座，阐明其调控机制在SZ发生发展中的规律。通过细胞、动物模型和SZ散发大样本，验证功能性基因座的调控机制及其对SZ表型变异影响的普遍性规律，为探索监测SZ发生发展的新型在体生物标记提供新的科学证据。

同卵双生子中的非孟德尔特征表型变异很可能是由于遗传效应的环境修饰因素造成的，而这些因素尚未阐明。在这里，我们通过对精神疾病单发病的同卵双胞胎的外周血DNA进行甲基组和基因组分析，研究等位基因特异性DNA甲基化（ASM）如何介导表型变异。我们发现大量不平衡的ASM位点表现出与表型-变异相关的变换。这些ASM通过影响转录因子、DNA甲基化和其他表观遗传标记物之间的相互作用，进而导致基因表达失调，最终增加了精神疾病易感性。同时，我们通过以其中最为显著的ASM位点rs2602749作为ASM变换导致基因失调作为例子。我们找到了与rs2602749高度连锁的SNP rs4854158是功能性位点。在精神分裂症病人中，ASM的变换介导了EIPR1的下调表达。高甲基化增强了PRC2和SPI1结合到rs4854158的结合能力。破坏rs4854158结合motif后可增加显著增加EIPR1的表达，显著增加囊泡的运输能力，促进突触的生长和神经的分化。全敲除EIPR1后会引起小鼠出生后致死，而杂合缺失会诱导小鼠产生对日夜节律光反应的行为学异常表型。本项目提供了一个筛选疾病相关风险基因座的新策略，并有助于理解和研究遗传学和表观遗传学因素相互作用介导精神疾病易感性的调控机制。.. 项目发表论文7篇（SCI论文6篇，中文论文1篇），另外2篇在审稿中；培养研究生7名（4名博士生，3名硕士生）。