Role of p53 in cell cycle checkpoints

p53 在细胞周期检查点中的作用

• 批准号: 8212549
• 负责人: James J Manfredi
• 金额: $ 34.12万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-03-01 至 2014-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8212549
• 关键词: Address; Affect; Apoptosis; Binding; Biology; Cdc25C protein; Cell Cycle; Cell Cycle Arrest; Cell Cycle Checkpoint; Cells; Clinical; Cyclin-Dependent Kinases; Cytokinesis; DNA; DNA Binding; DNA Damage; DNA damage checkpoint; Data; Defect; Down-Regulation; Ectopic Expression; Elements; Event; Frequencies; G1 Phase; Gene Targeting; Genes; Genomics; Health; Human; Indium; Individual; Malignant Neoplasms; Mediating; Mitosis; Mitotic; Molecular; Mutation; Null Lymphocytes; Outcome; Pathway interactions; Play; Post-Transcriptional Regulation; Protein p53; Proteins; Regulation; Repression; Research; Role; Site; Stimulus; TP53 gene; Transcriptional Regulation; Treatment Efficacy; Tumor Suppressor Proteins; base; chemotherapeutic agent; cyclin B1; gene repression; innovation; insight; neoplastic cell; novel; outcome forecast; prevent; promoter; protein degradation; repaired; research study; response; survivin; tumor; ubiquitin ligase

DESCRIPTION (provided by applicant): p53 has clearly been implicated as a tumor suppressor in human cancer with mutation of the p53 gene being a common event. p53 has a well-characterized role in mediating the cellular response to DNA damage. The checkpoint in the G1 phase has been shown to be strictly p53-dependent. Due to the existence of a G2/M checkpoint that occurs in its absence, the precise role of p53 in preventing mitotic entry has been elusive. The studies in this application will address this key aspect of p53 biology. Three specific aims are proposed to determine the molecular details of p53 function in this checkpoint in response to transient or sustained DNA damage. In the first aim, p53-dependent mechanisms of transcriptional regulation that affect mitotic entry and progression will be elucidated. The genes encoding mitotic regulators including Cdc25C, Survivin, Cdc20, and Cyclin B1 are targets for transcriptional downregulation. To elucidate the molecular basis, the regulation of the cdc25C gene will be studied as being representative. Insights gained in the detailed study of Cdc25C repression will then be examined for p53-dependent transcriptional downregulation of Survivin, Cdc20, and Cyclin B1. In the second aim, p53-dependent mechanisms of post-transcriptional regulation in response to DNA damage will be studied. These include novel roles for Mdm2 in affecting the ability of p21CIP1 to inhibit cyclin-dependent kinases and in regulating Cdc25C protein stability. Preliminary data show that protein stability of not only Cdc25C, but also Survivin, Cdc20, and Cyclin B1 is regulated by p53. This intriguing finding will be further explored. In the third aim, the role of p53 and its downregulated targets in mitotic entry and progression after transient or sustained DNA damage will be examined. Upon transient treatment with DNA damaging agents wild-type p53 cells reversibly arrest and repair the damage, whereas p53 null cells fail to do so and die. The molecular basis for these effects will be elucidated. The proposed studies address a central issue in understanding p53 function, namely how it mediates cell cycle checkpoints in response to DNA damage. The innovation of these planned experiments include the study of a new target for p53 that involves transcriptional repression occurring in a DNA binding-dependent manner, the novel observation that p53 regulates protein stability of particular mitotic regulators as part of checkpoint activation, and the intriguing possibility that Mdm2 plays a positive role as a downstream effector of p53-mediated cellular responses. The significance of this research relates to the clinical implications of selective targeting of tumor cells with a defective p53 pathway, especially given the frequency of p53 mutation in cancer. Taken together, the planned experiments will elaborate a detailed understanding of how p53 mediates DNA damage checkpoints. This is expected to provide new avenues of pursuit that are relevant for prognosis and treatment of human cancer. PUBLIC HEALTH RELEVANCE: The p53 protein has clearly been implicated in playing an important role as a tumor suppressor in human cancer with mutation of the p53 gene being a common event in human tumors. p53 has a well-characterized role in mediating the cellular response to DNA damage. As many cancer chemotherapeutic agents exert effects by causing damage to genomic DNA, understanding the molecular basis for the involvement of p53 will identify new avenues for enhanced therapeutic efficacy.

描述（由申请人提供）：p53显然被视为人类癌症中的肿瘤抑制因子，p53基因的突变是常见事件。 p53在介导对DNA损伤的细胞反应中具有很好的特征作用。 G1相中的检查点已被证明严格取决于P53。由于存在在缺席的情况下发生的G2/M检查点，因此p53在防止有丝分裂进入中的确切作用是难以捉摸的。该应用程序中的研究将解决p53生物学的这一关键方面。提出了三个具体目的，以确定该检查点中p53功能的分子细节，以响应瞬时或持续的DNA损伤。在第一个目的中，将阐明影响有丝分裂进入和进展的转录调节的p53依赖性机制。编码有丝分裂调节剂在内的基因，包括CDC25C，Survivin，Cdc20和Cyclin B1是转录下调的靶标。为了阐明分子基础，将研究Cdc25c基因的调节为代表性。然后将检查Cdc25c抑制的详细研究中获得的见解，以依赖p53依赖性的转录下调，survivin，cdc20和cyclin b1。在第二个目标中，将研究对DNA损伤的p53依赖性机制。这些包括MDM2在影响p21CIP1抑制细胞周期蛋白依赖性激酶和调节Cdc25c蛋白稳定性方面的能力中的新作用。初步数据表明，蛋白质的稳定性不仅CDC25C，还包括Survivin，Cdc20和Cyclin B1，受p53调节。这一有趣的发现将进一步探讨。在第三个目标中，将检查p53及其下调靶标在瞬时或持续DNA损伤后的下调目标。用DNA损伤药物瞬时处理后，野生型P53细胞可逆地捕捉和修复损伤，而p53无效细胞无法做到并死亡。这些作用的分子基础将被阐明。拟议的研究涉及理解p53功能的核心问题，即它如何响应DNA损伤介导细胞周期检查点。这些计划实验的创新包括对p53的新靶标的研究，涉及以DNA结合依赖性方式发生的转录抑制作用，p53调节特定有丝分裂调节剂的蛋白质稳定性作为检查点激活的一部分，以及MDM2具有较大的可能性，这是p55的效应。这项研究的意义与p53途径有缺陷的选择性靶向肿瘤细胞的临床意义有关，尤其是考虑到癌症中p53突变的频率。综上所述，计划的实验将详细了解p53如何介导DNA损伤检查点。预计这将提供与预后和治疗人类癌症有关的新途径。公共卫生相关性：p53蛋白显然与作为人类癌症的肿瘤抑制剂发挥了重要作用，p53基因是人类肿瘤中的常见事件。 p53在介导对DNA损伤的细胞反应中具有很好的特征作用。由于许多癌症化学治疗剂通过对基因组DNA造成损害发挥作用，因此了解p53参与的分子基础将确定新的途径，以提高治疗功效。