Heightened hypoxia and DNA methylation in heart defects of diabetic embryopathy

摘要 母体糖尿病导致先天性心脏缺陷(CHDS)的形成，其潜在机制仍然是 不清楚。母亲糖尿病导致发育中的胚胎缺氧，短期妊娠缺氧引起 CHDS。缺氧和DNA高甲基化在人类疾病中是相互关联的。DNA超甲基化是 涉及包括左心发育不良综合征(HLHS)在内的CHD，这是一种复杂而严重的CHD类型。我们发现 母体糖尿病增加了发育中心脏的缺氧和DNA甲基化。低氧 诱导因子1α(HIF-1α)上调DNA甲基转移酶(DNMT3a和DNMT3b)的表达 在发育中的小鼠心脏中的心脏祖细胞或来源于人类诱导的多能干细胞 (IPSCS)。去除DNMT3a和DNMT3b阻断早期心脏NKX2.5+细胞DNA高甲基化 祖细胞改善了糖尿病妊娠期间所有类型的CHD。因此，我们假设母体糖尿病 诱导低氧并触发低氧诱导因子1α(HIF-1α)途径的激活， 通过上调DNMT3a/b诱导DNA超甲基化。抑制缺氧、HIF-1α或DNA 高甲基化或双DNMT3a/b缺失可消除心脏祖细胞的功能缺陷 能减少冠心病，改善心肌细胞和心功能。第一心区 在这种严重类型的CHD中，缺陷导致HLHS的形成和心功能不全。测试我们的 假设，我们提出了三个具体目标。目标1将确定母体糖尿病是否导致 缺氧是早期心脏祖细胞DNA高甲基化导致CHD形成的原因。 我们将研究低氧是否通过上调早期心脏祖细胞的DNA甲基化来增加DNA甲基化 糖尿病妊娠中DNMT3a/b的表达与冠心病的关系目标2将调查母体的作用 糖尿病引起的基因异常导致早期功能缺陷的DNA高甲基化 心脏祖细胞和第一心场。我们将确定两个心脏中的DNA高甲基化 FIELS改变糖尿病妊娠期导致冠心病和心肌细胞功能障碍的基因表达 早期心脏祖细胞DNMT3a/b双缺失的研究AIM 3将确定HIF-1α是否升高 HLHS的活性和DNA高甲基化导致心肌细胞功能障碍 糖尿病妊娠。我们假设HIF-1α通路的持续激活和DNA超甲基化 导致母体糖尿病引起的先天性心脏病的心肌细胞功能障碍。成功完成后将剖析 低氧和DNA甲基化在糖尿病引起的冠心病中的关键作用并为 改善冠心病患者的心肌细胞功能。

Summary Maternal diabetes induces congenial heart defects (CHDs) formation and the underlying mechanism is still unclear. Maternal diabetes induces hypoxia in the developing embryo and short-term gestational hypoxia induces CHDs. Hypoxia and DNA hypermethylation have been interlinked in human diseases. DNA hypermethylation is implicated in CHDs including hypoplastic left heart syndrome (HLHS), a complex and severe CHD type. We found that maternal diabetes enhanced hypoxia and increased DNA methylation in the developing heart. Hypoxia inducible factor 1 alpha (HIF-1α) up-regulated the two de novo DNA methyltransferase (DNMT3a and DNMT3b) in cardiac progenitors in the developing mouse hearts or derived from human inducible pluripotent stem cells (iPSCs). Blockage of DNA hypermethylation by removing DNMT3a and DNMT3b in early cardiac Nkx2.5+ progenitors ameliorated all CHD types in diabetic pregnancy. Thus, we hypothesize that maternal diabetes induces hypoxia and triggers the activation of the hypoxia inducible factor 1 alpha (HIF-1α) pathway, which induces DNA hypermethylation by up-regulating DNMT3a/b. Inhibition of hypoxia, HIF-1α or DNA hypermethylation or double DNMT3a/b deletion abrogates the functional deficits in cardiac progenitors leading to CHD reduction and improvement of cardiomyocyte and cardiac function. First heart field defects contribute to HLHS formation and cardiac dysfunction in this severe type of CHDs. To test our hypothesis, we proposed three specific aims. Aim 1 will determine whether maternal diabetes-induced hypoxia is responsible for DNA hypermethylation in early cardiac progenitors leading to CHD formation. We will examine whether hypoxia increases DNA methylation in early cardiac progenitors by up-regulating DNMT3a/b expression leading to CHDs in diabetic pregnancy. Aim 2 will investigate the role of maternal diabetes-induced DNA hypermethylation in gene dysregulation that results in functional defects in early cardiac progenitors and the first heart field. We will determine whether DNA hypermethylation in both heart fields alters gene expression leading to CHDs and cardiomyocyte dysfunction in diabetic pregnancy by using DNMT3a/b double deletion in early cardiac progenitors. Aim 3 will determine whether heightened HIF-1α activity and consequent DNA hypermethylation contribute to cardiomyocyte dysfunction of HLHS in diabetic pregnancy. We hypothesize that persistent activation of the HIF-1α pathway and DNA hypermethylation contribute to cardiomyocyte dysfunction in maternal diabetes-induced CHDs. Successful completion will dissect the critical role of hypoxia and DNA methylation in diabetes-induced CHDs and provide mechanistic insights for improving cardiomyocyte function in CHD patients.