Mechanistic insight into oxidative stress-mediated genome instability

对氧化应激介导的基因组不稳定性的机制洞察 总结： 基因组不稳定性的特征是从DNA碱基突变到染色体的遗传改变 基因重排是许多遗传性人类疾病、各种癌症和早产儿的驱动因素， 老化染色体的不稳定性，特别是由于不准确的染色体分离引起的， 端粒和着丝粒功能障碍。许多流行病学研究都强调了 氧化应激暴露在端粒和着丝粒功能障碍的发生。然而，关键是， 功能障碍的潜在机制尚不清楚。氧化应激是由于 产生活性氧和细胞抗氧化防御之间的联系。它源于内生 来源以及来自环境来源（线粒体代谢、紫外线、空气污染、香烟 烟雾）。它的普遍存在突出了正确理解其对人类健康影响的重要性。一个主要 氧化应激的影响是诱导DNA氧化损伤，通过碱基切除修复 (BER)其中聚（ADP-核糖）聚合酶（PARP）是主要作用者的途径。PARP 1和PARP 2是 负责聚（ADP-核糖基）化，这是一种蛋白质的翻译后修饰， 招募和相互作用的蛋白质目标。本提案的目标是：（一）揭示机制 氧化应激介导的基因组不稳定性，重点是其对端粒和着丝粒的影响， 对基因组稳定性至关重要的基因组位点，以及（ii）破译PARP酶在保护 端粒和着丝粒DNA的氧化损伤。更具体地说，我们的目标是评估 慢性诱导氧化DNA碱基和BER单链断裂中间体的着丝粒和 端粒完整性我们还将确定和评估聚（ADP-核糖基）化对着丝粒和 端粒蛋白靶点。为此，我们将利用一种独特而创新的化学光遗传学工具， 端粒和着丝粒处的局部氧化DNA损伤，而不影响基因组的其余部分。这 将使我们能够明确地将表型变化和PARP依赖机制与端粒或 着丝粒损伤这些项目将填补一个长期存在的知识空白，如何聚（ADP-核糖基）化 在基因组的两个关键区域协调DNA修复。他们还将阐明氧化应激， 基因组不稳定性的一个普遍存在的因素，可以驱动许多人类疾病。最终，我们的工作将 有助于开发靶向基因组特定区域的新型治疗策略，并提供信息 已经广泛用于癌症治疗的PARP抑制剂的合理设计和使用。

Mechanistic insight into oxidative stress-mediated genome instability Summary: Genome instability is characterized by genetic alterations ranging from DNA base mutations to chromosome rearrangements that are drivers of many inherited human diseases, various types of cancer and premature ageing. Chromosome instability, especially, results from inaccurate chromosomal segregation caused by telomere and centromere dysfunction. Numerous epidemiologic studies have highlighted the central role of oxidative stress exposures in the occurrence of telomere and centromere dysfunction. Critically, however, the mechanisms underlying the dysfunction are not clearly understood. Oxidative stress results from an imbalance between the production of reactive oxygen species and cellular antioxidant defenses. It arises from endogenous sources as well as from environmental sources (mitochondria metabolism, UV light, air pollution, cigarette smoke). Its ubiquity highlights the importance of properly understanding its impacts on human health. A major impact of oxidative stress is the induction of oxidative DNA damage that are repaired by the base excision repair (BER) pathway in which poly(ADP-ribose) polymerases (PARPs) are major actors. PARP1 and PARP2 are responsible for the poly(ADP-ribosyl)ation, a post-translational modification of proteins that modulates the recruitment and interactions of their protein targets. The goals of this proposal are to (i) uncover the mechanisms of oxidative stress-mediated genome instability with a focus on its impact on telomeres and centromeres, two genomic loci crucial for genome stability and (ii) decipher the contribution of PARP enzymes in the protection of telomeric and centromeric DNA upon oxidative DNA damage. More specifically, we aim to evaluate the impact of chronic induction of oxidized DNA bases and BER single strand break intermediates on centromere and telomere integrity. We will also identify and assess the impact of poly(ADP-ribosyl)ation on centromeric and telomeric protein targets. To this end, we will leverage a unique and innovative chemoptogenetic tool that induces oxidative DNA damage locally at telomeres and at centromeres without impacting the rest of the genome. This will allow us to unequivocally link phenotypic changes and PARP dependent mechanisms to the telomeric or centromeric lesions. These projects will fill a long-standing gap of knowledge on how poly(ADP-ribosyl)ation orchestrates DNA repair at two crucial regions of the genome. They will also shed light on how oxidative stress, a ubiquitous factor of genome instability, can drive numerous human diseases. Ultimately, our work will contribute to the development of novel therapeutic strategies targeting specific regions of the genome and inform the rational design and use of the PARP inhibitors already widely used in cancer treatments.