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 机械：它们分裂很快，通常是多倍体。这些特点可能需要新的策略来实现 在正常的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是一种容易出错的跨损伤聚合酶，在癌细胞中经常上调，这 过度表达与过度的染色体损伤和阴性的临床结果相关。我们有 最近发现缺乏聚合酶theta的果蝇具有异常的表型和显示基因组 以快速S期和/或多倍体为特征的组织不稳定性，包括早期 胚胎、雌性生殖系中的卵泡细胞和组织母细胞。此外，我们还确定了以下角色 同源重组修复中的跨损伤聚合酶 这些初步数据确立了果蝇是研究组织和细胞特异性的极佳系统 跨损伤聚合酶的功能，并提供了一个机会来检验这一假设 跨损伤聚合酶在经历内源性复制应激的细胞中发挥着重要作用。我们会 利用一种新的LacZ报告系统来评估在 当聚合酶theta和其他跨损伤聚合酶时的复制和同源重组修复 突变或过度表达。此外，我们将与Lovett和Freudenreich实验室合作测试 形成准回文的三核苷酸重复和序列是否经历了高度的不稳定性 当位于双链断裂附近或处于内源复制胁迫条件下时。一起， 这些研究将大大推进我们的长期目标，了解如何使用和误用 跨损伤聚合酶有助于癌细胞基因组的不稳定。

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.