Role of DNA Glycosylase OGG1 in Oxidative Stress-Induced Innate Inflammation

DNA 碱基氧化损伤与炎症过程有关，但其存在重大缺陷 尽管付出了巨大努力，但仍了解其疾病病因。最丰富的 DNA 碱基损伤，8- 氧鸟嘌呤 (8-oxoG) 与炎症、各种与年龄相关的疾病和衰老过程有关。它是 通过 8-oxoG DNA 糖基化酶 (0GG1) 和 DNA 碱基切除修复 (BER) 从 DNA 中切除 途径。出乎意料的是，Oggi 基因敲除小鼠的超生理 8-oxoG 水平并未表现出明显的变化。 病理学；事实上，它们增强了对炎症的抵抗力。 DNA 中 8-oxoG 水平的增加 气道氧化暴露的最早事件；然而，它在引发炎症方面的作用是 怀疑但不理解。我们取得了意想不到的发现，表明 1) OGGI 耗尽 氧化暴露前的气道上皮显着降低先天炎症反应； 2） 0GG1结合其修复产物，游离8-oxoG碱基； 3) OGG1¿8-oxoG 复合物具有鸟嘌呤核苷酸 交换因子活性，4) 增加激活的小 Ras GTPases 的水平，5) 导致激活 NF-KB/RelA。项目 3 试图建立一种新的范式，其中 0GG1 引发的 DNA BER 是病因学上的 与氧化应激诱导的促炎基因表达和炎症有关。这将由 追求三个具体目标： 目标 1) 确定 OGGI 启动的 DNA BER 在炎症细胞中的作用 肺部氧化应激暴露后积累；目标 2) 阐明 OGGI 在激活中的作用 NF-kB/RelA 通路；目标 3) 识别 OGGI 诱导的触发促炎症的信号通路 基因表达和炎症。我们的假设将使用敲除/转基因进行测试 小鼠和细胞系以及基于 siRNA 的基因消融等最先进的分子技术 表达、实时 PCR、共聚焦显微镜、细胞因子/趋化因子和 RNA 阵列。这些研究 应该是第一个确定 OGGI 的作用并确定其促进先天性的新信号通路的人 肺部炎症。由于 OGG1 对 8-oxoG 的修复是连续的，因此这些研究的结果也可能 有助于了解过敏性哮喘、慢性阻塞性肺病、 气道重塑和肺部恶性肿瘤；每一项都对个人、家庭、健康造成重大负担 在美国和全世界的护理系统和整个社会。我们令人信服的初步数据， 此次POI的良好合作，以及UTMB优秀的资源和智力环境，使得 我们非常适合做这项工作。

Oxidative DNA base damage is linked to inflammatory processes, but there are major shortcomings in understanding their disease etiology despite considerable efforts. The most abundant DNA base lesion, 8- oxoguanine (8-oxoG) is linked to inflammation, various age-associated diseases, and aging processes. It is excised from DNA by the 8-oxoG DNA glycosylase (0GG1) and the DNA base excision repair (BER) pathway. Unexpectedly, supraphysiological 8-oxoG levels in Oggi knockout mice do not show major pathologies; in fact, they have increased resistance to inflammation. An increase in 8-oxoG levels in DNA is the earliest event upon oxidative exposure of airways; however, its role in triggering inflammation is suspected but not understood. We have made unexpected discoveries showing that 1) OGGI depletion from the airway epithelium before oxidative exposure significantly decreased innate inflammatory responses; 2) 0GG1 binds its repair product, free 8-oxoG base; 3) the OGG1¿8-oxoG complex has a guanine nucleotide exchange factor activity that 4) increases levels of activated small Ras GTPases and 5) leads to activation of NF-KB/RelA. Proiect 3 seeks to establish a novel paradigm in which 0GG1-initiated DNA BER is etiologically linked to oxidative stress-induced proinflammatory gene expression and inflammation. This will be done by pursuing three Specific Aims, to: Aim 1) establish the role of OGGI-initiated DNA BER in inflammatory cell accumulation after oxidative stress exposure in the lungs; Aim 2) elucidate the role of OGGI in activation of the NF-kB/RelA pathway; and Aim 3) identify the OGGI-induced signaling pathway(s) that trigger proinflammatory gene expression and inflammation. Our hypotheses will be tested using knock-out/transgenic mice and cell lines and such state-of-the-art molecular techniques as siRNA-based ablation of gene expression, real-time PCR, confocal microscopy, and cytokine/chemokine and RNA arrays. These studies should be the first to establish the role of OGGI and identify its novel signaling pathways that facilitate innate lung inflammation. As repair by 8-oxoG by OGG1 is continuous, the results from these studies may also shed light on understanding chronic inflammation in allergic asthma, chronic obstructive pulmonary disease, airway remodeling and lung malignancies; each poses a significant burden on individuals, families, health care systems and the entire society, here in the US and worldwide. Our compelling preliminary data, excellent collaborations in this POI, and UTMB's outstanding resources and intellectual environment make us uniquely suited to do this work.