Pathogenic Role of DNA-Damage Response Pathway in the Diabetic Retina

糖尿病视网膜病变与氧化应激、线粒体功能障碍和慢性 炎症和退变途径的激活。确凿的证据表明视网膜 线粒体氧化应激轴是几乎所有糖尿病的主要统一致病因素 细胞变化与视网膜并发症的发生有关。针对这些疾病的治疗 在人类临床试验中，单独的途径提供了令人失望的结果。同样，临床试验利用 抗氧化剂产生了同样模棱两可的结果。综上所述，这些试验表明 关于潜在机制的知识差距(S)将氧化应激与促炎因子激活联系起来 以及糖尿病视网膜中的促退化途径。基于我们以前在脊髓小脑性共济失调类型上的工作 3名患者，连同本修订申请中使用相关视网膜细胞提供的新数据，我们建议 糖尿病中ROS介导的DNA损伤慢性激活DNA损伤的新假说 反应(DDR)ATM(共济失调-毛细血管扩张突变)通路。DNA含量的增加与 糖尿病并发症的损害、累积和发展，包括视网膜病变。此外，还有一个 日益增长的共识是，ATM不仅充当DNA损伤传感器，协调受损部位的修复 维持基因组的完整性，但在调节细胞代谢感受器的活动方面也起着关键作用 干扰线粒体功能、细胞能量动态平衡、炎症和细胞凋亡。怎么了？ DDR-ATM途径相互连接各种信号成分，扰乱细胞能量代谢，并 增强促进退变的信号是深入研究的主题，但在视网膜中仍未被探索。 我们最近的研究表明，DDR途径的慢性激活干扰了线粒体 通过抑制调节线粒体的关键转录共激活因子pGC-1α活性来发挥作用 生物发生、氧化磷酸化和细胞能量动态平衡。我们新的初步数据 证明糖尿病视网膜中DNA损伤和ATM激活增加支持了我们的假设。这个 这项申请中提出的实验将检验糖尿病引起氧化的中心假设 应激导致双链dna损伤导致atm激活，导致pgc1α下调。 这影响了糖尿病视网膜中观察到的多种致病途径。我们假设自动取款机的激活 通过线粒体断裂诱导糖尿病引起的氧化应激显著放大 机制(目标1)、血管和神经元变性(目标2)和慢性炎症(目标3)。这些 AIMS有可能建立一个统一的分子机制，将增强的DNA损伤与 糖尿病中观察到的慢性氧化、退行性和炎症性异常。影响最大的是 我们的工作是提供一种调节机制，为高血糖如何影响提供一个新的解释 线粒体功能障碍，放大视网膜的氧化、炎症和退行性变化。 PHS 398/2590(06/09版)页面续格式页面

Diabetic retinopathy has been associated with oxidative stress, mitochondrial dysfunction, and chronic activation of inflammatory and degenerative pathways. Substantial evidence implicates the retinal mitochondrial ‒ oxidative stress axis as a major unifying pathogenic factor for virtually all diabetes-induced cellular changes implicated in the development of retinal complications. Therapies directed against these individual pathways have provided disappointing results in human clinical trials. Likewise, clinical trials utilizing antioxidants have produced equally ambiguous results. Taken together, these trials suggest a significant knowledge gap regarding underlying mechanism(s) linking oxidative stress to activation of pro-inflammatory and pro-degenerative pathways in diabetic retinas. Based on our previous work in Spinocerebellar ataxia type 3 patients, together with new data provided in this revised application using relevant retinal cells, we propose the novel hypothesis that ROS-mediated DNA damage in diabetes chronically activates the DNA damage response (DDR) ATM (ataxia-telangiectasia mutated) pathway. There is a strong link between increased DNA damage accumulation and development of diabetic complications including retinopathy. Also, there is a growing consensus that ATM not only acts as a DNA damage sensor to coordinate repair of damaged sites to maintain genome integrity but also plays a critical role in modulating the activities of cellular metabolic sensors to interfere with mitochondrial function, cellular energy homeostasis, inflammation, and apoptosis. How the DDR-ATM pathway interconnects various signaling components to disrupt cellular energy metabolism and enhance pro-degenerative signaling is the subject of intense investigation but remains unexplored in the retina. Our recent studies have shown that chronic activation of the DDR pathway interferes with mitochondrial function by suppressing PGC-1α activity, a key transcription co-activator that regulates mitochondrial biogenesis, oxidative phosphorylation, and cellular energy homeostasis. Our new preliminary data demonstrating increased DNA damage and ATM activation in diabetic retina supports our hypothesis. The experiments proposed in this application will test the central hypothesis that diabetes-induced oxidative stress causes double stranded DNA damage resulting in ATM activation, leading to downregulation of PGC1α that impacts multiple pathogenic pathways observed in diabetic retinas. We hypothesize that ATM activation induces a significant amplification of diabetes-induced oxidative stress via mitochondrial disruption by multiple mechanisms (aim 1), vascular and neuronal degeneration (aim 2), and chronic inflammation (aim 3). These aims have the potential to establish a unifying molecular mechanism that links enhanced DNA damage to chronic oxidative, degenerative, and inflammatory abnormalities observed in diabetes. The greatest impact of our work is to provide a regulatory mechanism offering a novel explanation for how hyperglycemia impacts mitochondrial dysfunction to amplify oxidative, inflammatory and degenerative changes in the retina. PHS 398/2590 (Rev. 06/09) Page Continuation Format Page