Mechanisms and Regulation of Human Translesion DNA Polymerases

描述(申请人提供)：复制DNA聚合酶(POLS)复制染色体DNA，但在DNA损伤剂引起的损伤处停滞不前。因此，专门的跨损伤POL已经进化成促进复制而不是DNA损伤，从而允许细胞在遗传毒剂面前增殖。然而，跨病变POL容易出错，因此会导致突变，从而导致肿瘤发生。 波尔？是一种新发现的跨损伤POL，参与双链断裂(DSB)修复。POL的过度表达会导致基因组不稳定和高水平的POL吗？在乳腺癌和结直肠癌中发现，这与较差的临床结果相对应。然而，降低Pol？的表达水平，会使各种肿瘤细胞对辐射敏感。波尔的抑制剂？因此有可能提高放射治疗的疗效和特异性。具体目标1将鉴定和表征Pol的抑制剂？用于潜在的癌症治疗。 由于跨病变POL容易出错，因此有必要对这些酶进行严格的监管，以将突变和癌症风险降至最低。跨损伤POL是如何被调节并招募到DNA损伤部位的，目前还知之甚少。特定目标2将研究跨损伤Poll的调节和募集？在跨病变合成过程中。 除了绕过病变，POL？复制DNA重组中间产物，称为D-环，它是在DSB修复过程中形成的。怎么回事？执行这一重要功能的人知之甚少。特指目标3将研究Poll？扩展了D-环复合中间体。 在指导阶段(目标1)进行的研究将使用高通量筛选和X射线结晶学来鉴定和表征Pol？的抑制剂。在癌症治疗中的潜在应用。在独立阶段(目标2和目标3)进行的研究最初将侧重于人类POL的机制和调节？作为一种模型酶。然后这些研究将扩展到Poll？与POL有相同的途径吗？如跨病变合成和D-环延伸。这项拟议的研究可能会为DNA损伤耐受性和癌症生物学的分子机制提供重要的见解。 公共卫生相关性：跨损伤DNA聚合酶是复制受损DNA的专门分子机器，它允许细胞在DNA损伤剂面前增殖。然而，跨病变聚合酶的突变和不适当的调节会增加癌症的风险。由于跨病变聚合酶在肿瘤中高表达，对肿瘤细胞具有放射和化疗的保护作用，因此研究跨病变聚合酶的作用机制和调控机制对于认识和治疗癌症是必要的。

DESCRIPTION (provided by applicant): 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 translesion 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. PUBLIC HEALTH RELEVANCE: Translesion DNA polymerases are specialized molecular machines that copy damaged DNA, which allows cells to proliferate in the face of DNA damaging agents. Mutation and improper regulation of translesion polymerases, however, increases the risk of cancer. Since translesion polymerases are overexpressed in cancers and protect tumor cells from radiation and chemotherapy, investigating the mechanisms and regulation of translesion polymerases is necessary for understanding and treating cancer.