Excision Repair of Environmental Telomere Damage

摘要 对人类群体、人体组织、动物模型和细胞培养的大量研究表明， 环境遗传毒性和氧化应激与端粒加速缩短和 功能障碍。染色体末端的端粒对于基因组的稳定和持续的细胞是必不可少的 端粒的增殖和功能障碍会导致人类的退行性疾病和癌症的发生。 该项目的目标是推动来自两个NIEHS的令人兴奋的发现和高度创新的工作 资助的R01奖项调查了端粒核苷酸碱基损伤和切除修复的后果。 这一R35方案的首要假设是端粒缩短和功能障碍由 环境遗传毒性和氧化应激，通过形成特定的碱基损伤和毒性修复而发生 直接干扰端粒复制和维持的中间体。与我们的合作者合作 开创了一种高度创新的化学遗传工具，选择性地诱导端粒DNA损伤。这 技术是变革性的，因为针对明确定义的端粒碱基损伤使我们能够 明确地将表型变化和健康结果归因于诱导的端粒损伤，消除了 其他地方的破坏造成的混乱影响。我们充分验证了这个系统的针对性形成了一个 端粒上常见的氧化鸟嘌呤损伤，值得注意的是，我们发现这一慢性生成 损伤导致类似端粒保护基因丢失的端粒功能障碍的深刻特征 蛋白质。本项目将探索和揭示DNA损伤引起的端粒丢失和 功能障碍。一项主要战略是分阶段扩展和修改这项灵活的技术 介绍碱基损伤、毒性修复中间体、笨重的单加合物和其他损伤类型。我们会 在损伤诱导后测量各种细胞和端粒终点，并将使用候选的和无偏见的 识别保护端粒免受各种形式环境污染所需蛋白质的方法 相关的DNA损伤。这种化学遗传工具已被改装用于模式生物，并作为 R35的进化我们将把我们在细胞培养中学到的东西转化为在转基因斑马鱼和小鼠身上的实验。 使用这个系统，我们将在关键器官和细胞类型中产生端粒损伤，并将测量其影响 器官功能和健康。这一计划将导致在机械理解方面的重大进步 环境相关形式的端粒DNA损伤如何影响端粒功能、细胞功能和 生物体健康。归根结底，从这个项目中获得的知识将对开发新的 策略：1)保存端粒以改善健康细胞中遗传毒性和氧化应激的影响 或者相反，这2)抑制了恶性细胞的端粒维持以阻止增殖。

Summary Numerous studies in human populations, human tissue, animal models and cell culture demonstrate that environmental genotoxic and oxidative stress are associated with accelerated telomere shortening and dysfunction. Telomeres at chromosome ends are essential for genome stability and sustained cell proliferation, and dysfunctional telomeres contribute to degenerative diseases and carcinogenesis in humans. The goals of this project are to advance exciting discoveries and highly innovative work from two NIEHS funded R01 awards investigating the consequences of nucleobase damage and excision repair at telomeres. The overarching hypothesis for this R35 proposal is that telomere shortening and dysfunction caused by environmental genotoxic and oxidative stress, occurs via formation of specific base lesions and toxic repair intermediates that directly interfere with telomere replication and maintenance. Working with collaborators we pioneered a highly innovative chemoptogenetic tool that selectively induces DNA lesions at telomeres. This technology is transformative because targeting well-defined base damage to telomeres allows us to unequivocally attribute phenotypic changes and health outcomes to the induced telomere lesions, eliminating confounding effects of damage elsewhere. We fully validated this system for the targeted formation of a common oxidative guanine lesion at telomeres, and remarkably, we discovered that the chronic generation this lesion induces profound hallmarks of telomere dysfunction that mimic genetic loss of telomere shelterin proteins. This project will probe and uncover the mechanisms of DNA lesion induced telomere loss and dysfunction. A major strategy is to extend and modify this flexible technology in a phased approach for introducing base damage, toxic repair intermediates, bulky monoadducts, and other lesion types. We will measure various cellular and telomeric endpoints after lesion induction and will use candidate and unbiased approaches to identify proteins required to protect telomeres against the various forms of environmentally relevant DNA damage. This chemoptogenetic tool has been adapted for use in model organisms, and as the R35 evolves we will translate what we learn in cell culture to experiments in transgenic zebrafish and mice. Using this system, we will generate telomeric damage in key organs and cell types and will measure the impact on organ function and health. This program will lead to significant advances in mechanistic understanding of how environmentally relevant forms of telomeric DNA lesions impact telomere function, cellular function, and organism health. Ultimately, knowledge gained from this program will be highly valuable for developing new strategies that 1) preserve telomeres to ameliorate the effects of genotoxic and oxidative stress in healthy cells or conversely, that 2) inhibit telomere maintenance in malignant cells to arrest proliferation.