Cellular Stress-Induced Gene Dysregulation in Heart Defects Formation of Diabetic Pregnancy

妊娠期糖尿病可诱发先天性心脏缺陷（CHDs），这是最常见的结构性出生缺陷。尽管在了解这些畸形的遗传原因方面已经取得了重大突破，但流行病学证据表明，非遗传因素在诱导冠心病方面发挥了重要作用。关于糖尿病如何影响心脏发育的知识是有限的。我们发现母体1型和2型糖尿病均可诱导氧化应激和高冠心病发生率，增加细胞凋亡，减少细胞增殖，并抑制心脏发生所必需的Wnt信号。因此，我们假设母体糖尿病通过增加NADPH氧化酶4的表达和线粒体ROS的产生来诱导胚胎心脏氧化应激。受损的Wnt信号通过下调心脏发育所必需的Wnt靶基因，抑制第二心区祖细胞、心肌细胞和心脏神经嵴细胞的关键信号通路和基因表达，介导糖尿病的致畸作用，导致冠心病。为了验证这一假设，我们提出以下目标。目的1将确定Nox4是否参与母体糖尿病诱导的氧化应激和异常心脏形成。我们将研究糖尿病是否通过JNK1/2增加Nox4的表达，以及第二心野（SHF） Isl1+祖细胞或心脏神经嵴细胞（cncc）中Nox4的缺失是否通过抑制氧化应激来降低糖尿病的致畸性。目的2将确定线粒体ROS生成增强是否有助于氧化应激和异常心脏形成。我们将研究糖尿病是否会诱导线粒体ROS，糖尿病增加的Nox4活性是否会导致线粒体功能障碍，以及线粒体特异性抗氧化酶SOD2的过表达是否会减少ROS介导的冠心病。目的3将确定典型Wnt拮抗剂Dkk1在母体糖尿病诱导的心脏缺陷中的作用。我们假设删除Dkk1可以减少冠心病。目的4将研究非典型Wnt信号抑制剂CaMKIIδ在母体糖尿病诱导的心脏缺陷中的作用。我们认为糖尿病激活CaMKIIδ导致非典型Wnt信号受损和心脏缺陷。

Pregestational maternal diabetes induces congenital heart defects (CHDs), the most common type of structural birth defects. Although there have been major breakthrough in understanding the genetic causes of these malformations, epidemiological evidence suggests that noninherited factors contribute substantially to the induction of CHDs. Knowledge of how diabetes adversely affects heart development is limited. We found that both maternal type 1 and type 2 diabetes induce oxidative stress and high rates of CHDs, increases apoptosis, decreases cell proliferation, and suppresses Wnt signaling essential for cardiogenesis. Therefore, we hypothesize that maternal diabetes induces oxidative stress in the embryonic heart by increasing NADPH oxidase 4 expression and mitochondrial ROS production. Impaired Wnt signaling mediates the teratogenic effect of diabetes by downregulating Wnt target genes essential for heart development and suppressing key signaling pathways and gene expression in the second heart field progenitors, cardiomyocytes and cardiac neural crest cells leading to CHDs. To test this hypothesis, we propose the following Aims. Aim 1 will determine whether Nox4 is involved in maternal diabetes-induced oxidative stress and abnormal heart formation. We will examine whether diabetes increases Nox4 expression though JNK1/2 and whether Nox4 deletion in the second heart field (SHF) Isl1+ progenitors or cardiac neural crest cells (CNCCs) reduces the teratogenicity of diabetes by inhibiting oxidative stress. Aim 2 will determine whether enhanced mitochondrial ROS production contributes to oxidative stress and abnormal heart formation. We will investigate whether diabetes induces mitochondrial ROS and whether diabetes-increased Nox4 activities contribute to mitochondrial dysfunction and overexpression of the mitochondria-specific antioxidant enzyme SOD2 will reduce the ROS-mediated CHDs. Aim 3 will determine the role of the canonical Wnt antagonist Dkk1 in maternal diabetes-induced heart defects. We hypothesize that deleting Dkk1 reduces CHDs. Aim 4 will investigate the role of the noncanonical Wnt signaling inhibitor, CaMKIIδ, in maternal diabetes- induced heart defects. We propose that diabetes activates CaMKIIδ leading to impaired noncanonical Wnt signaling and heart defects.