The BRCA1-GADD45 Pathway and Genomic Stability

BRCA1-GADD45 通路和基因组稳定性

• 批准号: 6850886
• 负责人: QIMIN ZHAN
• 金额: $ 25.16万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6850886
• 关键词: DNA damage; apoptosis; brca gene; breast neoplasms; cell line; chemical stability; gene expression; gene interaction; genetic promoter element; genetic regulation; genetic regulatory element; genome; human genetic material tag; neoplasm /cancer genetics; posttranslational modifications; tissue /cell culture; transcription factor

Breast cancer susceptibility gene, BRCA1, has been implicated in the maintenance of genomic integrity. However, the molecular mechanism(s) by which BRCA1 plays a role in maintenance of genomic fidelity remains to be defined. Interestingly, recent studies in our group and others have demonstrated that BRCA1 can regulate the GADD45, a p53-regulated stress inducible gene that plays an important role in cellular response to DNA damage. These results have evidently linked GADD45 to BRCA1 and raised the possibility that GADD45 might be a BRCA1-downstream effector and mediate BRCA1's role in maintenance of genomic stability. Therefore, this proposal seeks to define the biochemical mechanism(s) by which BRCA1 transactivates the GADD45 gene, and to define the role of the BRCA1-GADD45 pathway in the induction of apoptosis following genotoxic stress. The long-term objective described in this application will specifically focus on three key issues: (1). To characterize the GADD45 gene as a BRCA1's downstream effector. We will define the BRCA1-regulatory elements in the GADD45 promoter and identify the proteins that modulate the BRCA1 transactivation of the GADD45 promoter. (2). To define whether the GADD45 is an essential player in the BRCA1-induced apoptosis. We will analyze the induction of apoptosis following expression of GADD45 and BRCA1. We will also examine the alterations of the BRCA1-activated apoptosis and BRCA1-induced growth suppression in GADD45- deficient cells. (3). Our most recent studies demonstrated that BRCA1 is cleaved by caspase-3 during apoptosis induced by DNA damage. This DNA damage-activated cleavage results in an accumulated 90-kDa band of the BRCA1 C-terminus. Therefore, we will first determine whether the BRCA1 cleavage is required for BRCA1-activated apoptosis following DNA damaging agents. We will also determine the functional role of the cleaved 90-kDa band of the BRCA1 C-terminus in activation of apoptosis. Finally, we will analyze the role of this cleaved product in the BRCA1 transactivation of the GADD45 promoter. The studies proposed in this application would define a novel pathway (BRCA1-GADD45) controlling apoptosis following DNA damage and provide information regarding the biochemical mechanism by which BRCA1 regulates its targeted genes. Since apoptosis is closely associated with the therapeutic sensitivity, the perspective outcome will also provide insight into the development of therapeutic agents.

乳腺癌易感基因 BRCA1 与基因组完整性的维持有关。然而，BRCA1 在维持基因组保真度方面发挥作用的分子机制仍有待确定。有趣的是，我们小组和其他人最近的研究表明，BRCA1 可以调节 GADD45，这是一种 p53 调节的应激诱导基因，在细胞对 DNA 损伤的反应中发挥重要作用。 这些结果显然将 GADD45 与 BRCA1 联系起来，并提出了 GADD45 可能是 BRCA1 下游效应子并介导 BRCA1 在维持基因组稳定性中的作用的可能性。 因此，本提案旨在确定 BRCA1 反式激活 GADD45 基因的生化机制，并确定 BRCA1-GADD45 通路在基因毒性应激后诱导细胞凋亡中的作用。本申请中描述的长期目标将特别关注三个关键问题：（1）。鉴定 GADD45 基因作为 BRCA1 下游效应子的特征。 我们将定义 GADD45 启动子中的 BRCA1 调控元件，并鉴定调节 GADD45 启动子的 BRCA1 反式激活的蛋白质。 （2）。确定 GADD45 是否是 BRCA1 诱导细胞凋亡的重要参与者。 我们将分析 GADD45 和 BRCA1 表达后细胞凋亡的诱导。我们还将检查 GADD45 缺陷细胞中 BRCA1 激活的细胞凋亡和 BRCA1 诱导的生长抑制的变化。 （3）。我们最近的研究表明，BRCA1 在 DNA 损伤诱导的细胞凋亡过程中被 caspase-3 裂解。 这种 DNA 损伤激活的切割导致 BRCA1 C 末端累积 90 kDa 的条带。 因此，我们首先确定DNA损伤剂后BRCA1激活的细胞凋亡是否需要BRCA1裂解。 我们还将确定 BRCA1 C 末端切割的 90-kDa 带在细胞凋亡激活中的功能作用。 最后，我们将分析该切割产物在 GADD45 启动子的 BRCA1 反式激活中的作用。本申请中提出的研究将定义一种控制 DNA 损伤后细胞凋亡的新途径 (BRCA1-GADD45)，并提供有关 BRCA1 调节其靶基因的生化机制的信息。 由于细胞凋亡与治疗敏感性密切相关，因此前瞻性结果也将为治疗药物的开发提供深入的见解。