MECHANISMS OF DNA DAMAGE TRIGGERED S PHASE CHECKPOINTS

描述（改编自申请人摘要）：本研究的目标是 确定S期DNA损伤检查点响应的机制， 阻止DNA复制。这些检查点是细胞暂时停止 通过细胞周期，以便有时间修复DNA损伤， 细胞分裂如果这些检查站不能适当地工作， 可能的结果。轻微的DNA损伤可能导致永久性突变， 基因组更大的DNA损伤会导致染色体断裂，重排， 易位甚至是灾难性的细胞分裂 首席研究员的初步研究表明，他可以使用 SV4O体外DNA复制系统，其主要由人 细胞提取物，以生化研究S期DNA损伤依赖 检查站用DNA损伤剂预处理培养的人细胞 导致体外SV4O DNA复制的抑制， 抑制体内染色体DNA复制。作为模型药物， 主要研究者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 在复制中，adozelesin灭活已知的细胞DNA复制蛋白， RPA，而bizelesin诱导存在反式作用的DNA复制 抑制剂.本提案的目标是了解adozelesin如何产生 在RPA失活中的作用，并鉴定 bizelesin，确定复制蛋白，这是目标， 反式抑制剂，并确定这第二种机制如何导致 抑制DNA复制。 在其进展过程中，大多数形式的癌症已经失去了一个或多个它们的功能。 DNA损伤检查点反应。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破坏癌细胞。阐明 这些DNA损伤依赖的检查点途径和了解机制 它们是如何工作的，最终将有助于设计更好的抗癌药物， 治疗，并将提供信息，将允许改善 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.