Excision Repair of Environmental Telomere Damage

总结 在人群、人体组织、动物模型和细胞培养中的大量研究表明， 环境遗传毒性和氧化应激与加速端粒缩短有关， 功能障碍染色体末端的端粒对于基因组的稳定性和细胞的持续生长至关重要。 增殖和功能失调的端粒有助于人类的退行性疾病和致癌作用。 该项目的目标是推进两个NIEHS的令人兴奋的发现和高度创新的工作 资助R01奖研究端粒的核碱基损伤和切除修复的后果。 R35的主要假设是端粒缩短和功能障碍是由 环境遗传毒性和氧化应激，通过形成特定的基底损伤和毒性修复发生 直接干扰端粒复制和维持的中间体。与合作者一起， 开创了一种高度创新的化学光遗传学工具，选择性地诱导端粒的DNA损伤。这 技术是变革性的，因为针对端粒的明确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， 其他地方的损害的影响。我们充分验证了该系统的目标形成， 端粒中常见的鸟嘌呤氧化损伤，值得注意的是，我们发现， 损伤诱导端粒功能障碍的深刻标志，模拟端粒遮蔽的遗传丢失 proteins.本项目将探讨和揭示DNA损伤诱导端粒丢失的机制， 功能障碍一个主要的战略是分阶段地扩展和修改这种灵活的技术， 引入碱基损伤、毒性修复中间体、庞大的单加合物和其它损伤类型。我们将 在损伤诱导后测量各种细胞和端粒终点，并将使用候选和无偏 鉴定保护端粒免受各种形式的环境污染所需的蛋白质的方法 相关的DNA损伤这种化学光遗传学工具已被改造用于模式生物，并且作为 我们将把我们在细胞培养中学到的东西转化为转基因斑马鱼和小鼠的实验。 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。 对器官功能和健康的影响这一计划将导致机械理解的重大进展， 端粒DNA损伤的环境相关形式如何影响端粒功能，细胞功能， 有机体健康最终，从该计划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 或相反，2）抑制恶性细胞中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.