Mechanisms and Regulation of Human Translesion DNA Polymerases

项目摘要 复制型DNA聚合酶（pols）复制染色体DNA，但在DNA损伤引起的损伤处停止 剂.因此，特化的跨损伤pol已经进化为促进DNA损伤后的复制， 使细胞在面对基因毒性物质时增殖。然而，转换pols容易出错， 从而诱发突变，导致肿瘤发生。 Pol是一种新发现的跨损伤pol，参与双链断裂（DSB）修复。 pol的过表达导致基因组不稳定，在乳腺和结肠直肠中发现高水平的pol 癌症，这对应于较差的临床结果。然而，降低pol的表达水平， 使各种肿瘤细胞对放射线敏感。因此，pol的抑制剂可能增加功效， 放射治疗的特异性。具体目标1将鉴定和表征pol抑制剂， 潜在的癌症治疗方法。 由于translesion pols是容易出错的，因此需要对这些酶进行严格的调控，以最大限度地减少 突变和癌症风险。跨病变pols是如何被调节和募集到DNA损伤位点的， 不太了解。具体目标2将研究跨病变pol的调节和募集。 在经损伤合成期间。 除了绕过病变，pol复制DNA重组中间体，称为D环， 在修复DSB的过程中形成。人们对pol如何执行这一重要功能知之甚少。具体 目的3将研究pol延伸D环重组中间体的机制。 在指导阶段（目标1）进行的研究将使用高通量筛选和X射线 晶体学来鉴定和表征用于癌症治疗的潜在应用的POL抑制剂。 在独立阶段进行的研究（目标2和3）最初将侧重于机制， 作为模型酶的人pol的调节。这些研究将被扩展到涉及的pol 在与pol相同的途径中，例如Dopeson合成和D-环延伸。拟议的研究是 可能为DNA损伤耐受性和癌症的分子机制提供重要的见解 生物学

Project summary Replicative DNA polymerases (pols) copy chromosomal DNA, but stall at lesions caused by DNA damaging agents. Specialized translesion pols have therefore evolved to promote replication past DNA damage thus allowing cells to proliferate in the face of genotoxic agents. Translesion pols are, however, error-prone and thus induce mutations which can lead to tumorigenesis. Pol is a newly discovered translesion pol which is involved in double-strand break (DSB) repair. Overexpression of pol causes genome instability and high levels of the pol are found in breast and colorectal cancers, which corresponds to a poor clinical outcome. Reducing the expression level of pol , however, sensitizes various tumor cells to radiation. Inhibitors of pol are therefore likely to increase the efficacy and specificity of radiation therapy. Specific Aim 1 will identify and characterize inhibitors of pol for potential cancer therapeutics. Since translesion pols are error-prone, stringent regulation of these enzymes is necessary for minimizing mutagenesis and cancer risk. How translesion pols are regulated and recruited to sites of DNA damage is poorly understood. Specific Aim 2 will investigate the regulation and recruitment of translesion pol during translesion synthesis. In addition to bypassing lesions, pol replicates DNA recombination intermediates called D-loops which are formed during the repair of DSBs. How pol performs this important function is poorly understood. Specific Aim 3 will investigate the mechanism by which pol extends D-loop recombination intermediates. Studies perfomed during the mentored stage (Aim 1) will use high-throughput screening and X-ray crystallography to identify and characterize inhibitors of pol for potential applications in cancer therapeutics. Research performed during the independent stage (Aims 2 and 3) will initially focus on the mechanisms and regulation of human pol as a model enzyme. These studies will then be extended to pol which is implicated in the same pathways as pol such as transleson synthesis and D-loop extension. The proposed research is likely to provide significant insight into the molecular mechanisms of DNA damage tolerance and cancer biology.