Molecular Signalling Pathways and Cellular Stress in Diabetic Embryopathy

描述(由申请人提供)：糖尿病妇女所生婴儿中有高达10%会发生先天性畸形。最优的血糖控制很难实现和维持，即使是短暂的高血糖暴露也会导致畸形。目前的建议是基于我们关于PKC通路的发现，PKC通路与糖尿病胚胎病变的诱导密切相关。由于PKC激活下游的分子中间产物尚未确定，我们提出了一个新的假设，即母体高血糖诱导的PKCA/d激活通过DNA高甲基化降低SIRT2的表达。SIRT2的下调阻止了持续的抗氧化酶的表达，并诱导了Marcks的过度乙酰化，从而促进了Marcks的磷酸化。发育中的神经管中依赖PKC的SIRT2下调和Marcks的磷酸化是导致神经上皮细胞凋亡和NTD形成的细胞应激的原因。目的1研究PKCA和PKCd是否通过DNA高甲基化抑制糖尿病胚胎病变中SIRT2的表达。我们假设PKCA和PKCd增加了从头DNA甲基转移酶(DNMT3A/B)的表达，从而诱导SIRT2启动子的高甲基化并抑制其表达。目的2研究SIRT2在糖尿病胚胎病变中PKC诱导的细胞应激、MARCKS磷酸化和NTD形成中的作用。我们的工作假设是，SIRT2的下调降低了抗氧化酶的表达，从而导致氧化和内质网应激，并导致Marcks乙酰化和磷酸化增加，从而导致细胞应激。目的3将确定Marcks磷酸化在糖尿病诱导的细胞应激、细胞凋亡和NTD形成中的因果作用。我们将验证依赖于PKCA/d的Marcks磷酸化诱导细胞应激和线粒体功能障碍，导致细胞凋亡和NTD形成的假设。该项目的成功将极大地填补目前关于导致糖尿病胚胎病变的事件的知识库的空白。

DESCRIPTION (provided by applicant): Congenital malformations occur in up to 10% of babies born to diabetic women. Optimal glycemic control is difficult to achieve and maintain, and even transient exposure to hyperglycemia can cause malformations. This current proposal is formulated on the basis of our findings relative to the PKC pathway, which is critically involved i the induction of diabetic embryopathy. Because the molecular intermediates downstream PKC activation have not been determined, we have advanced a novel hypothesis that maternal hyperglycemia-induced PKCa/d activation reduces the expression of SIRT2 through DNA hypermethylation. SIRT2 downregulation prevents sustainable antioxidant enzyme expression and induces MARCKS hyperacetylation, which contributes to MARCKS phosphorylation. PKC-dependent SIRT2 downregulation and MARCKS phosphorylation in the developing neural tube are responsible for cellular stresses that cause neuroepithelial cell apoptosis and NTD formation. Aim 1 will determine whether PKCa and PKCd suppress SIRT2 expression through DNA hypermethylation in diabetic embryopathy. We hypothesize that that PKCa and PKCd increases the expression of de novo DNA methyltransferases (DNMT3A/B), which induce hypermethylation in the SIRT2 promoter and inhibit its expression. Aim 2 will determine the role of SIRT2 in PKC-induced cellular stress, MARCKS phosphorylation and NTD formation in diabetic embryopathy. Our working hypothesis is that downregulation of SIRT2 decreases antioxidant enzyme expression, which results in oxidative and endoplasmic reticulum stress, and leads to an increase in MARCKS acetylation and phosphorylation, which contributes to cellular stress. Aim 3 will determine the causal role of MARCKS phosphorylation in diabetes-induced cellular stress, apoptosis and NTD formation. We will test the hypothesis that PKCa/d-dependent MARCKS phosphorylation induces cellular stress and mitochondrial dysfunction, resulting in apoptosis and NTD formation. The success of this project will significantly fill the gaps in the current knowledge base regarding events that cause diabetic embryopathy.