Glycemic Control and Progession of Diabetic Retinopathy

摘要 糖尿病视网膜病变仍然是工作年龄成人失明的主要原因。标志性临床研究 我已经证明，即使在多年来实现并保持良好的血糖控制后， 由先前血糖控制不良所灌输的血糖控制变得难以撤销，并且结果表明， 先前的高血糖会留下后遗症。这种“新陈代谢” 记忆的现象也在体外和体内复制。 糖尿病视网膜病变的体内实验模型。终止大鼠高血糖症并不逆转 线粒体功能障碍和DNA（mtDNA）损伤， DNA修复酶MutL同源物1（Mlh 1）仍然存在 线粒体DNA受损 转录继续危及 电子传递链（ETC）。 基因组和结构/生理学的稳定性对于线粒体内稳态是重要的; 融合酶丝裂融合蛋白2（Mfn 2）即使在高血糖停止后也保持低于正常。最近 研究已经证明，基因组功能也受到表观遗传修饰的调节， 在不改变DNA序列的情况下调节基因表达的修饰。我们最近的研究 表明糖尿病激活了视网膜及其毛细血管细胞中的DNA甲基化机制， 激活并不因高血糖的逆转而终止。因此，中心假设是，由于持续的 表观遗传修饰、线粒体DNA和结构/功能仍然受损。功能失调 线粒体继续进入自由基的恶性循环，停止高血糖不能 阻止早期糖尿病视网膜病变的发展。 目的1研究表观遗传修饰在线粒体基因组稳定性中的作用。我们的模型预测 由于持续的Mlh 1启动子DNA超甲基化，线粒体基因组的稳定性仍然存在， 受损和受损的mtDNA转录继续破坏ETC系统， 损害目的2将确定表观遗传修饰如何调节线粒体的结构/生理 稳态，并将研究Mfn 2启动子的表观遗传修饰在继续研究中的作用。 线粒体损伤目的3将确定保护线粒体内稳态的作用， 通过直接抑制正常视网膜病变期间的表观遗传修饰来抵抗糖尿病视网膜病变停止， 这是高血糖症引起的该计划将采用体外（视网膜内皮细胞）和体内（视网膜 来自啮齿动物的微血管维持在不同的血糖控制）代谢记忆模型中，并将利用 完全优化的分子生物学和药理学方法。我们的总体目标是了解 糖尿病进展中线粒体持续损伤的分子机制 视网膜病变该建议是基于一个可检验的中心假设，这些创新的研究进行了一个 显著的翻译影响，因为它们预计将定义表观遗传学在持续的线粒体 损害，并确定新的治疗靶点，以抑制这种威胁视力的疾病的进展。

ABSTRACT Diabetic retinopathy remains the leading cause of blindness in working-age adults. Landmark clinical studies have documented that even after achieving and maintaining good glycemic control for many years, damage instilled by the prior poor glycemic control becomes difficult to undo, and the results have suggested that the prior hyperglycemia leaves a legacy. This `metabolic memory' phenomenon is also duplicated in vitro and in vivo experimental models of diabetic retinopathy. Termination of hyperglycemia in rats does not reverse mitochondrial dysfunction and DNA (mtDNA) damage, DNA repair enzyme MutL homolog 1 (Mlh1) remains subnormal, and impaired mtDNA transcription continues to compromise the electron transport chain (ETC). Stability of both genomic and structure/physiology are important for mitochondrial homeostasis; mitochondrial fusion enzyme mitofusin 2 (Mfn2) also remains subnormal even after cessation of hyperglycemia. Recent studies have documented that genomic functions are also modulated by epigenetic modifications, the modifications that regulate gene expression without changing the DNA sequence. Our recent research has shown that diabetes activates DNA methylation machinery in the retina and its capillary cells, and this activation is not terminated by reversal of hyperglycemia. Thus, the central hypothesis is that due to sustained epigenetic modifications, mitochondrial DNA and structure/function remain damaged. Dysfunctional mitochondria continues to fuel into the vicious cycle of free radicals, and cessation of hyperglycemia fails to arrest the progression of incipient diabetic retinopathy. Aim 1 will investigate the role of epigenetic modification in mitochondrial genomic stability. Our model predicts that due to sustained Mlh1 promoter DNA hypermethylation, mitochondrial genomic stability remains compromised, and impaired mtDNA transcription continues to damage ETC system, fueling into mitochondrial damage. Aim 2 will determine how epigenetic modifications regulate mitochondrial structural/physiological homeostasis, and will investigate the role of epigenetic modifications of Mfn2 promoter in continued mitochondrial damage. Aim 3 will determine the effect of protection of mitochondrial homeostasis in the resistance of diabetic retinopathy to halt by directly inhibiting epigenetic modifications during normal glycemia, which has followed hyperglycemia. The plan will employ in vitro (retinal endothelial cells) and in vivo (retinal microvessels from rodents maintained in varied glycemic control) models of metabolic memory, and will utilize fully optimized molecular biological and pharmacological approaches. Our overall goal is to understand the molecular mechanism responsible for continued mitochondrial damage in the progression of diabetic retinopathy. The proposal is based on a testable central hypothesis, and these innovative studies carry a significant translational impact as they are expected to define the role of epigenetics in continued mitochondrial damage, and identify novel therapeutic targets to inhibit the progression of this sight-threatening disease.