HYDIN基因突变在云南地区散发先天性房间隔缺损发生中的作用机制研究

Congenital heart disease (CHD) seriously endangered the health care systems. Sporadic atrial septal defects (ASD) is the most common subtype of CHD. In our previous studies, we observed patients with ASD had higher mutation frequency of HYDIN gene locus 71098693 in Yunnan province, the migration and proliferation ability of myocardial cell were reduced and apoptosis was increased after knock down HYDIN gene. But the mechanism of HYDIN gene in the ASD is unclear. According to reports in the literature, the cilia dysfunction plays a central role in CHD, mitochondria play an important role in the cilia dysfunction, and HYDIN gene mutations can lead to the cilia dysfunction through the loss of cilia C2b gene wire core tube structure. Therefore, we hypothesize that HYDIN gene mutations may be involved in the incidence of ASD by regulating the mitochondria and cilia function of myocardial cell. In this study, we aim to further characterize the role of the HYDIN gene mutations in the pathogenesis of sporadic atrial septal defects in Yunnan. We will focuses on the effect of HYDIN gene mutations on the mitochondria and cilia function of myocardial cell by the three levels of ASD clinical samples, cells and rat model. Our results will uncover the mechanism of HYDIN gene mutations during the progression of ASD, and will help with molecular markers of prenatal screening and early therapeutic interventions of this disease.

先天性心脏病（CHD）严重危害人类健康，散发房间隔缺损（ASD）是最常见的CHD亚型。我们前期研究发现：HYDIN基因71098693位点突变频率在云南省散发ASD患者中显著增高；敲降HYDIN基因后心肌细胞迁移和增殖能力降低，凋亡增加。但HYDIN基因在ASD中的作用机制尚不明确。据文献报道，纤毛功能障碍在CHD的发生中起核心作用，线粒体在纤毛功能障碍中发挥重要调控作用，而HYDIN基因突变可引起纤毛基因丝中心微管C2b结构缺失，导致纤毛功能障碍。因此，我们推测HYDIN基因突变可能通过调控心肌细胞线粒体和纤毛功能参与ASD的发生。本项目拟在前期工作的基础上，通过ASD临床样本、细胞和大鼠模型三个层次开展研究，集中分析HYDIN基因突变对心肌细胞线粒体和纤毛功能的影响并由此导致ASD的分子作用机制，为ASD产前筛查分子标记和早期干预靶点的探寻提供理论依据。

先天性心脏（CHD）病是胚胎期由于环境因素、遗传因素及其共同作用而导致心血管系统发育异常所引起，目前发病机理尚未完全阐明。课题组前期工作发现云南省CHD总体患病率高于全国水平，房间隔缺损（ASD）是最常见的CHD亚型。HYDIN功能异常导致心肌细胞增殖能力受损和凋亡增加，HYDIN基因突变与ASD发生相关。本部分研究是在前期工作的基础上，深入流行病学分析及临床样本、细胞实验、动物实验，结果发现：(I)CHD的危险因素包括：①患儿：出生低体重（<2500 g）、早产（<37周）是；②母亲：妊娠年龄大于40岁、孕期感染、妊娠期糖尿病、妊娠期高血压、受教育时间短；③CHD家族史的儿童CHD患病风险增高；(II)建立干细胞定向心肌细胞分化体系，高效获得多能干细胞及胚胎干细胞来源的心肌细胞；(III)HYDIN过表达增强人HES3细胞中GATA4及其下游靶点的表达；(IV)敲降HYDIN降低了HES3细胞中GATA4及其下游靶点的表达，其作用被GATA4拯救过表达所逆转；(V) 敲降HYDIN降低转基因小鼠GATA4表达，增加ASD风险；(VI)与人类ASD风险相关的c.A2207C突变HYDIN降低了HES3细胞GATA4的表达。(VII) RAC1表达水平与HYDIN呈正相关，RAC1可能是HYDIN调控GATA4的关键信号分子。通过以上研究，进一步丰富了云南省CHD的流行病学数据，干细胞定向心肌细胞分化体系为后续科研实验提供了良好的种子细胞，HYDIN基因功能的解析为ASD早期干预靶点的探寻提供有效依据。