Hyperglycemia of Maternal Diabetes Induces Cardiac Isl1 Positive Progenitor Dysfunction Leading to Heart Defects

妊娠前母体糖尿病是一种与先天性心脏病（CHD）增加五倍相关的非遗传因素。第二心脏领域（SHF）的祖细胞，标记为Isl 1，驱动心脏管的延伸，在循环形态发生和心腔形成。糖尿病诱导的CHD的潜在机制尚不清楚，但一种机制可能涉及母体糖尿病抑制Isl 1 + SHF祖细胞驱动的心脏发生。在过去的十年中，我们一直专注于CHD患者心脏祖细胞的生物学和再生能力。关键是要确定体内糖尿病和体外高葡萄糖对Isl 1+祖细胞在胚胎发育和出生后的生物学效应，以最大限度地提高其在CHD患者中的再生和保护潜力。因此，我们的总体假设是，母体糖尿病的高血糖症在心脏发育的关键时期通过增强的氧化应激、主要UPR传感器IRE 1 α及其下游转录因子XBP 1的激活诱导Isl 1 + SHF祖细胞功能障碍，其负责DNA超甲基化和SHF基因沉默，导致RNA甲基转移酶胃L14和m6 A RNA甲基化的抑制。抑制细胞应激或调节DNA/RNA甲基化可改善SHF祖细胞的缺陷、CHD形成和这些祖细胞的潜在再生能力。目的1探讨糖尿病母体高血糖是否通过氧化应激诱导Isl 1 + SHF祖细胞功能障碍。我们假设糖尿病引起线粒体功能障碍，心脏形态发生过程中通过诱导氧化应激和减轻氧化应激的超氧化物歧化酶1（SOD 1），增加冠心病的形成糖尿病妊娠。目的2：探讨UPR主要感受器IRE 1 α及其下游效应子XBP 1在糖尿病妊娠合并CHD的Isl 1 + SHF祖细胞中的作用。我们将检验以下假设：氧化应激是Isl 1 + SHF祖细胞中ER应激和UPR的原因，通过灭活主要UPR传感器IRE 1 α或其下游转录因子XBP 1抑制ER应激-UPR通路可减少糖尿病诱导的CHD。目的3将确定Isl 1 + SHF祖细胞中DNA甲基转移酶抑制的RNA甲基化是否有助于糖尿病诱导的CHD以及这些祖细胞的治疗意义。我们预期，DNA甲基化的增加抑制了Isl 1+祖细胞功能所必需的RNA甲基转移酶样14（胃L14）和RNA N（6）-甲基腺苷（m6 A），并且在Isl 1+祖细胞中特异性地减少DNA甲基化或恢复RNA甲基化可以减少CHD并增加这些细胞的治疗价值。

Pregestational maternal diabetes is a noninherited factor associated with a fivefold increase in congenital heart defects (CHDs). The second heart field (SHF) progenitors, marked by Isl1, drive the heart tube extension during looping morphogenesis and cardiac chamber formation. The underlying mechanism of diabetes-induced CHDs is unknown but one mechanism may involve the inhibition of Isl1+ SHF progenitor-driven cardiogenesis by maternal diabetes. During the last decade, we have focused on the biology and regenerative capability of cardiac progenitors in CHD patients. It is critical to determine the biological effects of diabetes in vivo and high glucose in vitro on Isl1+ progenitors during embryogenesis and postnatally in order to maximize their regenerative and protective potentials in CHD patients. Therefore, our overarching hypothesis that hyperglycemia of maternal diabetes induces Isl1+ SHF progenitor dysfunction during the critical period of cardiac development through heightened oxidative stress, activation of the major UPR sensor IRE1α and its downstream transcription factor XBP1, which is responsible for DNA hypermethylation and SHF gene silencing leading to repression of RNA methyltransferase METTL14 and m6A RNA methylation. Suppressing cellular stress or modulating DNA/RNA methylation ameliorates defects in SHF progenitors, CHD formation and potential regenerative capacity of these progenitors. Aim 1 will determine whether hyperglycemia of maternal diabetes induces Isl1+ SHF progenitor dysfunction during heart development through oxidative stress. We hypothesize that diabetes causes mitochondrial dysfunction and during cardiac morphogenesis through the induction of oxidative stress and that mitigation of oxidative stress by superoxide dismutase 1 (SOD1) alleviates CHD formation in diabetic pregnancy. Aim 2 will determine the role of the major UPR sensor IRE1α and its downstream effector XBP1 in Isl1+ SHF progenitors leading to CHDs in diabetic pregnancy. We will test the hypothesis that oxidative stress is responsible for ER stress and UPR in Isl1+ SHF progenitors and that suppressing the ER stress-UPR pathway by inactivating either the major UPR sensor IRE1α or its downstream transcription factor XBP1 reduces diabetes-induced CHDs. Aim 3 will determine whether DNA methyltransferases-suppressed RNA methylation in Isl1+ SHF progenitors contributes to diabetes- induced CHDs and the therapeutic implications of these progenitors. We expect that that increased DNA methylation represses RNA methyltransferase-like 14 (METTL14) and RNA N(6)-methyladenosine (m6A) essential for Isl1+ progenitor function and that reducing DNA methylation or restoring RNA methylation specifically in Isl1+ progenitors reduces CHDs and increases the therapeutic values of these cells.