Glucose-Mediated Remodeling of Cardiac DNA Methylation

尽管心脏病总体上减少了，但发生心力衰竭的风险增加了 在糖尿病患者中仍高出2倍。我们实验室和其他实验室的证据表明 发现葡萄糖水平和摄取的波动直接导致心血管疾病 (CVD)通过改变蛋白质、DNA和基因表达。就葡萄糖而言，临床研究已经 表明在严格的血糖控制之后，疾病进展的易感性持续数年或 即使是几十年，这一过程也被称为“血糖记忆”。我们实验室的一个长期目标是 了解葡萄糖在血糖记忆形成中的作用，并确定这些变化 改变疾病进程。最近，表观遗传调控的机制，包括 帮助包装DNA的组蛋白的修饰和DNA的直接修饰(如 甲基化)，与血糖记忆有关。确定分子的一个关键障碍 机制一直是在完整的心脏上放置标记以测试疾病易感性的能力。 在过去的2-5年里，有两个新的进展将葡萄糖介导的蛋白质 翻译后修饰，O-GlcN酰化，处于这一探索的前沿。具体来说，O- GlcN酰化是组蛋白编码的一部分。第二，调节O-GlcN酰化的蛋白质 与DNA甲基化的蛋白质相互作用，在葡萄糖和DNA甲基化之间提供第二个链接 表观遗传学。目前提案的目标是确定通过何种机制 葡萄糖的波动改变了DNA甲基化，以及这些变化是如何改变基因表达和 心脏功能。由于糖尿病和心力衰竭是代谢成分很强的疾病，我们 将侧重于葡萄糖介导的表观遗传变化如何改变获得性脑脊髓炎的代谢和能量学 心脏病。我们开发了两个新的小鼠模型来验证这一假设。第一个版本 在我们的可诱导心肌细胞特异性葡萄糖转运蛋白GLUT4表达模型的基础上， 第二种是心肌细胞O-GlcNAc调节的新模型。从而独一无二地允许我们 直接检测心肌细胞葡萄糖转运和GlcN酰化在CVD中的作用。我们的 初步数据定义了持续的DNA甲基化变化，这些变化增加了对压力的敏感性- 超负荷肥大。在这项提案中，我们将：确定DNA甲基化改变的机制 (目标1)，确定这些表观遗传修饰是否改变了心脏收缩和代谢功能障碍 对常见的糖尿病合并高血压的反应(目标2)，并确定O-GlcNAc 仅此一项就足以增加疾病易感性(目标3)。总的来说，这些项目的完成 研究将提供对葡萄糖调节的机制基础的基本见解。 心脏基因表达参与糖尿病心血管疾病的发生发展。

Despite overall reductions in heart disease, the increased risk of developing heart failure has remained 2-fold greater among people with diabetes. Evidence from our laboratory and others has identified that fluctuations in glucose level and uptake directly contributes to cardiovascular disease (CVD) by modifying proteins, DNA, and gene expression. In the case of glucose, clinical studies have shown that following tight glycemic control, susceptibility to disease progression is sustained years or even decades in a process termed “glycemic memory”. A long-term goal of our laboratory is to understand the role of glucose in the formation of glycemic memory and determine if these changes alter disease progression. Recently the mechanism of epigenetic regulation, which consists of modifications of the histone proteins that help package DNA and direct modifications of the DNA (e.g. methylation), is linked to glycemic memory. A critical barrier in determining the molecular mechanisms has been the ability to place the marks in the intact heart to test disease susceptibility. Two novel advances have taken place over the last 2-5 years that place the glucose-mediated protein post-translational modification, O-GlcNAcylation, at the forefront of this quest. Specifically, O- GlcNAcylation is part of the histone code. Secondly, the proteins that regulate O-GlcNAcylation interact with the proteins that tailor DNA methylation, providing a second link between glucose and epigenetics. The objective of the current proposal is to determine the mechanism by which fluctuations in glucose alter DNA methylation and how these changes alter gene expression and cardiac function. As diabetes and heart failure are diseases with strong metabolic components, we will focus on how glucose-mediated epigenetic changes alter metabolism and energetics in acquired heart disease. We have developed two novel mouse models to test this hypothesis. The first builds upon our model of inducible cardiomyocyte-specific expression of the glucose transporter, GLUT4, and the second is a new model of cardiomyocyte O-GlcNAc regulation. Thus uniquely allowing us to directly test the role that cardiomyocyte glucose delivery and GlcNAcylation have on CVD. Our preliminary data define persistent DNA methylation changes that increase susceptibility to pressure- overload hypertrophy. In this proposal we will: determine the mechanism of altered DNA methylation (Aim 1), determine if these epigenetic modifications alter contractile and metabolic dysfunction in response to a common diabetic co-morbidity of hypertension (Aim 2), and determine if O-GlcNAc alone is sufficient to increase disease susceptibility (Aim 3). Collectively, the completion of these studies will provide fundamental insights into the mechanistic basis for glucose in the regulation of cardiac gene expression contributing to the development of diabetic CVD.