MECHANISMS OF DNA DAMAGE TRIGGERED S PHASE CHECKPOINTS

描述(摘自申请者的摘要)：本研究的目标是 确定S期DNA损伤检查点反应的机制 阻止DNA复制。这些检查点是像元临时停止的方式 通过细胞周期，以便有时间修复DNA损伤，在 细胞分裂。如果这些检查点没有适当地执行操作，则会有各种 可能的结果。轻微的DNA损伤会导致永久性的基因突变 基因组。更大的DNA损伤会导致染色体断裂、重排， 易位，甚至灾难性的细胞分裂。 首席调查员的初步研究表明，他可以使用 SV4O体外DNA复制系统，主要由人类支持 细胞提取液，生化研究S期依赖的DNA损伤 检查站。DNA损伤剂对培养的人细胞的预处理 导致体外抑制SV4O DNA复制，这与 体内抑制染色体DNA复制。作为模型药物， 首席研究员选择使用两种抗癌化疗药物。他 已经表明，这两种药物触发不同的机制来阻止DNA 复制，adozelesin使一种已知的细胞DNA复制蛋白失活， RPA，而Bizelesin诱导反式DNA复制的存在 抑制剂。这项建议的目标是了解阿多泽林是如何产生效果的 在RPA失活中的作用，并鉴定 Bizelesin，确定作为此目标的复制蛋白 反式抑制物，并确定第二种机制如何导致 抑制DNA复制。 在进展过程中，大多数形式的癌症都失去了一种或多种 DNA损伤检查点响应。这可能解释了为什么大多数癌症疗法 通常通过灾难性的细胞分裂来摧毁癌细胞。澄清 这些依赖DNA损伤的检查点通路及其机制的理解 它们的工作原理，最终将有助于设计更好的抗癌药物 治疗，并将提供信息，使改进 针对特定肿瘤的治疗策略。

DESCRIPTION (adapted from applicant's abstract): The goal of this research is to identify the mechanisms by which the S-phase DNA damage checkpoint responses arrest DNA replication. These checkpoints are the way cells temporarily stop passage through the cell cycle to allow time for repair of DNA damage, prior to cell division. If these checkpoints don't act appropriately, there are various possible outcomes. Minor DNA damage can lead to permanent mutations in the genome. Greater DNA damage can lead to chromosomal breakage, rearrangement, translocations, and even catastrophic cell division. The principal investigator's preliminary studies have shown that he can use an SV4O in vitro DNA replication system, which is supported predominantly by human cell extracts, to biochemically investigate S phase DNA damage dependent checkpoints. Pretreatment of cultured human cells with DNA damaging agents leads to inhibition of in vitro SV4O DNA replication that parallels the inhibition of chromosomal DNA replication in vivo. As model drugs, the principal investigator has chosen to use two anti-cancer chemotherapeutics. He has shown that these two drugs trigger different mechanisms for arresting DNA replication, adozelesin inactivates a known cellular DNA replication protein, RPA, while bizelesin induces the presence of a trans-acting DNA replication inhibitor. The goals of this proposal are to understand how adozelesin results in the inactivation of RPA, and to identify the trans-inhibitor induced by bizelesin, identify the replication protein that is the target of this trans-inhibitor, and to determine how this second mechanism results in the inhibition of DNA replication. During their progression, most forms of cancer have lost one or more of their DNA-damage checkpoint responses. This likely explains why most cancer therapies generally destroy cancer cells through catastrophic cell division. Elucidating these DNA-damage dependent checkpoint pathways and understanding the mechanisms of how they work, will ultimately aid in the design of better anti-cancer therapeutics, and will provide information that will allow for improved therapeutic strategies for particular tumors.