Heightened hypoxia and DNA methylation in heart defects of diabetic embryopathy

总结 母体糖尿病导致先天性心脏缺陷（CHD）的形成，其潜在机制仍然是 不清楚母体糖尿病在发育中的胚胎中诱导缺氧，短期妊娠缺氧诱导 冠心病缺氧和DNA超甲基化在人类疾病中相互关联。DNA超甲基化是 与CHD有关，包括左心发育不良综合征（HLHS），一种复杂和严重的CHD类型。我们发现 母亲的糖尿病加剧了发育中心脏的缺氧和DNA甲基化。缺氧 诱导因子1 α（HIF-1α）上调两种从头DNA甲基转移酶（DNMT 3a和DNMT 3b） 在发育中的小鼠心脏的心脏祖细胞中或源自人诱导性多能干细胞 （iPSC）。去除DNMT 3a和DNMT 3b对Nkx2.5+心肌细胞DNA高甲基化的阻断作用 在糖尿病妊娠中，祖细胞改善了所有类型的CHD。因此，我们假设母亲糖尿病 诱导缺氧并触发缺氧诱导因子1 α（HIF-1α）通路的激活， 其通过上调DNMT 3a/B诱导DNA超甲基化。抑制缺氧、HIF-1α或DNA 高甲基化或双DNMT 3a/B缺失消除了心脏祖细胞的功能缺陷 导致CHD减少和改善心肌细胞和心脏功能。第一心场 这些缺陷导致HLHS形成和这种严重类型CHD中的心功能障碍。来测试我们 假设，我们提出了三个具体目标。目的1将确定母体糖尿病诱导的 缺氧是导致CHD形成的早期心脏祖细胞中DNA超甲基化的原因。 我们将研究缺氧是否通过上调心肌细胞DNA甲基化水平， 糖尿病妊娠中DNMT 3a/B表达导致CHD目的2将研究产妇的作用 糖尿病诱导的基因失调中的DNA超甲基化，导致早期糖尿病患者的功能缺陷。 心脏祖细胞和第一心野。我们将确定是否在两个心脏的DNA甲基化 fields改变基因表达，导致糖尿病妊娠中的CHD和心肌细胞功能障碍， 早期心脏祖细胞中的DNMT 3a/B双缺失。目标3将确定是否升高HIF-1α 活动和随之而来的DNA超甲基化有助于HLHS的心肌细胞功能障碍， 糖尿病妊娠我们推测HIF-1α通路的持续激活和DNA高甲基化可能与HIF-1 α通路的激活有关。 导致母体糖尿病诱导的CHD中的心肌细胞功能障碍。成功完成将解剖 缺氧和DNA甲基化在糖尿病诱导的CHD中的关键作用，并为以下方面提供机制见解： 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.