SMAD4错义突变与先天性心脏病易感性的相关性研究

Association Study Between SMAD4 Missense Mutations and Susceptibility to Congenital Heart Disease

SMAD4在心脏发育过程中发挥重要作用,已有研究显示,Smad4缺陷小鼠心脏功能异常。为了进一步探究SMAD4基因错义突变与先天性心脏病(congenital heart disease, CHD)发生的相关性,本研究选取了来自中国山东汉族的417例CHD患者样本和213例健康对照样本,并靶向SMAD4的编码区进行深度测序。我们在SMAD4的编码区检测到两个错义突变c.685C>A(p.L229M)和c.740G>A (p.G247E),并经Sanger测序验证两者均为杂合突变,SMAD4^(L229M)和SMAD4^(G247E)在不同物种间的保守性都很高。蛋白免疫印迹实验显示,两种突变型对SMAD4的蛋白表达量没有明显影响,双荧光素酶报告基因实验结果表明,与野生型SMAD4相比较,SMAD4^(L229M)和SMAD4^(G247E)对TGF-β信号通路的激活作用均有所减弱。我们的研究表明,SMAD4的病例特有的错义突变可能通过减弱TGF-β信号通路的活性从而导致先天性心脏病的发生。

SMAD4 plays a vital role in cardiogenesis and Smad4 knockout mice show cardiac dysfunction. To further study the correlation between missense mutations of SMAD4 and the susceptibility to congenital heart disease(CHD), 417 CHD patient samples, and 213 healthy control samples from the Chinese Han population in Shandong were collected in this study, and we found two missense mutations in the coding region of SMAD4, c.685C>A(p.L229M) and c.740G>A(p.G247E), which were further verified that both were heterozygous mutations by Sanger sequencing. SMAD4^(L229M) and SMAD4^(G247E) are highly conserved among different mammals. Western analysis showed the two mutations had no effects on the protein expression of SMAD4. However, the result of dual-luciferase reporter assay indicated that compared with wild type SMAD4, the two mutations attenuated the activity of TGF-βsignaling pathway. Our research suggests that the case-specific missense mutations in SMAD4 may cause congenital heart disease by attenuating the activity of the TGF-β signaling pathway.