P53 MEDIATED G2/M CHECKPOINT CONTROL

研究表明，作为回应，细胞会阻止细胞周期的进展 给DNA损伤留出时间进行修复，从而避免有害的 突变和染色体损伤的影响。哺乳动物细胞中的细胞停滞 通常依赖于P53肿瘤抑制因子的蛋白产物 吉恩。P53基因在不同类型的人类中经常发生突变 癌症，人们认为肿瘤的发生过程是 与P53在细胞周期调控中的功能密切相关 检查站控制。暴露于DNA损伤停滞的细胞在G1和 细胞周期的G2期。G1期停滞已被证明是 部分由P53依赖的基因转录激活所介导 它编码p21Cip1/Waf1/SDl1蛋白，细胞周期蛋白依赖性蛋白 抑制剂。研究还表明，P53可能与DNA有关 损伤诱导G2停滞；然而，P53介导的G2的机制(S) 对逮捕的理解还不是很清楚。 我们最近发现了一种新的基因Wip1，它是 P53依赖的DNA损伤引起的转录激活 举止。Wip1基因编码p60wip1蛋白，具有同源性。 以及一种2C型蛋白磷酸酶的生化特性。 初步数据显示p60wip1的异位表达 将细胞周期停滞在G2期，并且停滞是 与肌动蛋白激酶活性的急剧下降有关 Cdc2/Cyclin B复合体。我们认为p60wip1是一个下游 P53介导的G2检查点控制的效应因子。的具体目标 这是以下内容。目标1.通过生化方法鉴定和鉴定 鉴定p60wip1的G2检查点的蛋白质组分 在G2逮捕期间与交互。目标2.确定是否 P60wip1与G2期细胞中的未知蛋白相互作用 鉴定、克隆和鉴定这些蛋白质。目标3.目标 确定Wip1基因的改变是否会影响亲属 细胞对电离辐射和其他DNA损伤的敏感性 探员们。

Studies have shown that cells arrest cell cycle progression in response to DNA damage to allow time for repair, thus avoiding the deleterious affects of mutations and chromosomal damage. Arrest in mammalian cells is often dependent on the protein product of the p53 tumor suppressor gene. The p53 gene is frequently mutated in diverse types of human cancers and it is thought that the process of tumorigenesis is intimately related to the functionality of p53 in mediating cell cycle checkpoint control. Cells exposed to DNA damage arrest in both G1- and G2-phase of the cell cycle. G1-phase arrest has been shown to be mediated in part by p53-dependent transcriptional activation of the gene which encodes p21Cip1/Waf1/SDl1 protein, cyclin-dependent kinase inhibitor. Studies have also suggested that p53 may be involved in DNA damage-induced G2 arrest; however, the mechanism(s) of p53-mediated G2 arrest are not well understood. We have recently identified a novel gene, Wip1 that is transcriptionally-activated in response to DNA damage in a p53-dependent manner. The Wip1 gene encodes p60wip1 protein which exhibits homology and biochemical characteristics of a type 2C protein phosphatase. Preliminary data is presented showing that ectopic expression of p60wip1 arrests cell cycle progression in G2-phase and that the arrest is associated with a dramatic decrease in the kinase activity of cdc2/cyclin B complexes. We propose that p60wip1 is a downstream effector of p53-mediated G2 checkpoint control. The Specific Aims of this are the following. Aim number 1. To identify and biochemically characterize protein components of the G2 checkpoint that p60wip1 interacts with during G2 arrest. Aim number 2. To determine whether p60wip1 interacts with unknown proteins in G2 arrested cells and to identify, clone, and characterizes these proteins. Aim number 3. To determine whether alterations in the Wip1 gene affect the relative sensitivity of cells to ionizing radiation and other DNA-damaging agents.