Translesion Synthesis DNA Polymerases and Genome Instability

描述（由申请方提供）：自发发生或由外源性遗传毒物诱导的突变是癌症的根本原因。几乎所有的遗传毒性诱导的突变都是由DNA损伤和受损DNA通过特异性跨损伤合成（TLS）DNA聚合酶的复制引起的，所述TLS DNA聚合酶比正常的复制型DNA聚合酶更不精确。TLS聚合酶在复制未受损的DNA时也非常容易出错，因此构成了需要控制以避免疾病的基因组不稳定性的持久来源。虽然TLS聚合酶募集到DNA损伤位点的机制相对较好地理解，但限制其参与正常复制的机制却不太清楚。PI的实验室发现DNA聚合酶的参与？(Pol?)在未受损DNA的复制中，许多因素阻碍了复制的进展，包括正常复制机制的缺陷、叉在自然障碍物处停滞以及用治疗性复制抑制剂治疗。这项建议旨在确定全球性的机制，规范的程度容易出错的合成波尔？在体内DNA损伤和生理条件下。在具体目标1中，我们将确定dNTP池的检查点依赖性升高在形成Pol？错误特征中的作用。在具体目标2，我们将确定如何贡献的波尔？DNA合成受复制动力学和叉不对称性的调节。酵母酿酒酵母模型系统将用于目标1和2中提出的研究，目的是使用在酵母中获得的数据进一步促进我们对人类细胞诱变机制的理解。在具体目标3中，我们将描述对人细胞复制缺陷的致突变反应机制。拟议的工作将导致更好地了解在正常细胞中操作的诱变过程，以及由环境遗传毒物或治疗干预引起的诱变过程。从长远来看，学会操纵这些过程将有助于降低癌症发病率，延迟进展并改善治疗结果。

DESCRIPTION (provided by applicant): Mutations occurring spontaneously or induced by exogenous genotoxicants are a root cause of cancer. Nearly all genotoxicant-induced mutations result from DNA damage and replication of the damaged DNA by specialized translesion synthesis (TLS) DNA polymerases that are less accurate than normal replicative DNA polymerases. TLS polymerases are also highly error-prone when copying undamaged DNA, thus constituting a persistent source of genomic instability that needs to be controlled to avoid disease. While the mechanisms of TLS polymerase recruitment to the sites of DNA damage are understood relatively well, the mechanisms that restrict their participation in the normal replication are much less clear. The PI's laboratory has discovered that the participation of DNA polymerase ? (Pol?) in the copying of undamaged DNA is promoted by a variety factors that impede the progression of the replication, including defects in the normal replication machinery, fork stalling at natural impediments and treatment with therapeutic replication inhibitors. This proposal seeks to define the global mechanisms that regulate the extent of error-prone synthesis by Pol? in vivo in DNA damaging and physiological conditions. In Specific Aim 1, we will determine the role of checkpoint dependent elevation of dNTP pools in shaping the error signature of Pol?. In Specific Aim 2, we will determine how the contribution of Pol? to DNA synthesis is regulated by the replication dynamics and fork asymmetry. The yeast Saccharomyces cerevisiae model system will be utilized in the studies proposed in Aims 1 and 2, with the goal of using the data obtained in yeast to further advance our understanding of the mechanisms of mutagenesis in human cells. In Specific Aim 3, we will characterize the mechanism of the mutagenic response to replication defects in human cells. The proposed work will lead to a better understanding of the mutagenic processes that operate in normal cells, as well as those induced by environmental genotoxicants or therapeutic interventions. In the long run, learning to manipulate these processes will help reduce cancer incidence, delay progression and improve therapy outcome.