SWI/SNF复合物在胚胎心脏房间隔及室间隔发育中的表观遗传调控机制

Congenital heart disease is a problem with the heart's structure and function that is present at birth for abnormal development. It is the most common type of birth defect. Atrial septum defect and ventricular septum defect are the most common types registered at 25％～57％and 10％～20％. From an epigenetic perspective, thousands of genes in the genomes of multicellular eukaryotes are normally expressed spatially and temporally in a controlled fashion. Epigenetic alterations do not involve changes in the sequence of nucleotide base pairs or in the dosage or arrangement of genes but involve chemical alterations on the genome that modulate gene expression. The spatial and temporal regulation of genes is an important aspect of embryo development. Our preliminary study suggests, there is a coordination control network combinding with SWI/SNF between the expression of heart development key genes and regulation factors in the development of atrial septum and ventricular septum. At least 2 forms of modulation of chromatin structure have been described: covalent modification of histone tails by acetylation, methylation, phosphorylation, ubiquitination, sumoylation and/or ADP ribosylation, and disruption of histone-DNA contacts by ATP-dependent chromatin remodeling complexes. Chromatin remodeling proteins have been shown to alter local chromatin structure and facilitate recruitment of essential factors required for transcription. Alteration of the chromatin architecture by ATP-dependent remodeling complexes is considered a significant step in transcriptional regulation of many eukaryotic genes. The SWI/SNF complex, a kind of ATP-dependent remodeling complexes, regulates the transcription activity of many genes by changing the chromatin structure around the genes. Each SWI/SNF complex takes part in different biological process for different subunits assembly. This work plans to do some researches about coordination control network combinding with different SWI/SNF subunits assembly in the heart development to reveal the portfolio models, regulation pathway and Interaction. We wish to reveal epigenetic regulation mechanism mediated by different SWI/SNF subunits assembly. The study aims to establish a research model and reference system against congenital heart disease. This research has important significance to demonstrate the alternative expression of genes aroused by abnormal expression of epigenetic messages in congenital heart defects.

先心病是指胚胎时期心脏及血管组织发育异常而导致出生时即存在的心脏、血管结构及功能异常，是小儿时期最常见的出生缺陷。其中VSD及ASD是较为常见的类型，分别占先心病的25％～57％及10％～20％。本课题组前期研究结果提示胚胎心脏房间隔、室间隔发育过程中，心脏发育关键基因与其表达调控因素之间可能存在着不同SWI/SNF复合物协同调控的网络。本工作拟通过研究胚胎心脏发育过程中参与表观遗传调控的SWI/SNF亚基组合模式、调控途径及其与TFs相互作用的网络，揭示小鼠房间隔及室间隔发育过程中ATP依赖的染色质重塑复合物介导的表观调控机制，为ASD、VSD防治策略的建立提供研究模型及参照体系。该研究对于明确表观遗传信息在基因的选择性表达在表观遗传失调所致先天性心脏缺陷发生、发展中的作用机制具有重要意义。

1先心病是胚胎时期心脏及血管组织发育异常而导致出生时即存在的心血管结构及功能异常，研究心脏发育相关基因的基因表达表观遗传调控有利于揭示先心病的发病机制。SWI/SNF 复合物是胚胎心脏的发育过程中重要的表观遗传调控模式。本研究通过基因芯片、非标记定量蛋白质组学方法筛选出在小鼠胚胎心脏发育过程中具有时序性变化特点的SWI/SNF 复合物亚基及心脏发育相关基因，并从基因及蛋白水平证实其相关性。另外，SWI/SNF 复合物通过 BRG1 在特定基因启动子区的募集、重塑基因局 部染色质、调控增殖相关基因的表达，可能参与到胚胎心脏发育的基因特异表型的编程过程。因此在小鼠胚胎心脏发育过程中SWI/SNF核心基团及其亚基形成的复合物也呈现出时序性变化的特点，本研究通过免疫共沉淀等方式剖析出小鼠胚胎心脏发育过程中SWI/SNF复合物的调控网络，对于进一步探索心脏及血管组织发育畸形的机制提供了及其重要的线索。. 心脏发育是一个极其复杂的过程，存在很多心脏、血管发育的重要时期，若此时心脏发育相关基因出现时间或空间的表达异常就会导致先天性心脏病的发生。本研究在筛选并验证出小鼠胚胎心脏发育过程中具有时序性表达特点的重要心脏发育相关基因后，在间充质干细胞向心肌细胞定向分化的细胞模型中进一步证实SWI/SNF复合物核心基团的表达水平直接影响了心肌细胞的分化及增殖。. 因此，本研究揭示了小鼠胚胎心脏发育过程中参与表观遗传调控的 SWI/SNF 亚基组合模式、调控途径及其与 心脏相关基因相互作用的网络，揭示了胚胎心脏发育过程中 ATP 依赖的染色质重塑复合物介导的表观调控机制，为进一步探讨表观遗传信息对基因的选择性表 达在表观遗传失调所致先天性心脏缺陷发生、发展中的作用机制提供实验室证据。