Mutagenesis due to Translesion Polymerase Usage during Replication and Repair

癌细胞具有两种特性，这对DNA复制和修复造成了极大的负担。 机器：它们分裂迅速，往往是多倍体。这些特征可能需要新的策略， 在正常细胞分裂过程中不被利用的DNA复制。例如，DNA的表达 聚合酶theta是一种易出错的跨损伤聚合酶，在癌细胞中经常上调， 过表达与过度的染色体损伤和阴性临床结果相关。我们有 最近发现，缺乏聚合酶θ的果蝇具有异常的表型和显示基因组， 组织中的不稳定性，其特征在于快速S期和/或多倍性，包括早期阶段 胚胎、雌性生殖系中的卵泡细胞和成组织细胞。此外，我们还确定了 同源重组修复中的跨损伤聚合酶 这些初步的数据建立了果蝇作为一个优秀的系统，在其中研究组织和细胞特异性 跨损伤聚合酶的功能，并提供了一个机会来测试的假设， 跨损伤聚合酶在经历内源性复制应激的细胞中发挥重要作用。我们将 利用一种新的lacZ报告系统，以评估突变的频率和类型， 当聚合酶θ和其它跨损伤聚合酶 是突变的或是过度表达的此外，我们将与洛维特和弗罗伊登赖希实验室合作， 三核苷酸重复和形成准回文的序列是否经历了增加的不稳定性 当位于双链断裂附近或在内源性复制应激条件下时。在一起， 这些研究将大大推进我们的长期目标，以了解如何使用和滥用 跨损伤聚合酶导致癌细胞中的基因组不稳定性。

Cancer cells possess two properties which place an extreme burden on the DNA replication and repair machinery: they divide rapidly and are often polyploid. These characteristics may require novel strategies for DNA replication that are not utilized during normal cell division. As an example, the expression of DNA polymerase theta, an error-prone translesion polymerase, is frequently upregulated in cancer cells and this overexpression correlates with excessive chromosomal damage and a negative clinical outcome. We have recently found that Drosophila lacking polymerase theta have abnormal phenotypes and display genome instability in tissues that are characterized by rapid S phases and/or polyploidy, including early stage embryos, follicle cells in the female germline, and histoblasts. In addition, we have identified roles for translesion polymerases in homologous recombination repair These preliminary data establish Drosophila as an excellent system in which to investigate tissue- and cellspecific functions of translesion polymerases and provide an opportunity to test the hypothesis that translesion polymerases play important roles in cells that experience endogenous replication stress. We will utilize a novel lacZ reporter system to assess the frequency and types of mutations that arise during replication and homologous recombination repair when polymerase theta and other translesion polymerases are mutated or overexpressed. In addition, we will collaborate with the Lovett and Freudenreich labs to test whether trinucleotide repeats and sequences that form quasi-palindromes experience heightened instability when located near double-strand breaks or under conditions of endogenous replication stress. Together, these studies will significantly advance our long-term goal to understand how the use and misuse of translesion polymerases contributes to genome instability in cancer cells.