Roles of Chromatin Modification in BRCA1 Dependent DNA Repair

染色质修饰在 BRCA1 依赖性 DNA 修复中的作用

• 批准号: 10061558
• 负责人: Roger A Greenberg
• 金额: $ 38.24万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10061558
• 关键词: Accounting; Address; Affect; BRCA mutations; BRCA1 Protein; BRCA1 gene; BRCA2 Mutation; Biochemical; CRISPR screen; Cancer Biology; Cancer Etiology; Cell Survival; Cells; Chromatin; Clinical; Collaborations; Complement; DNA Damage; DNA Double Strand Break; DNA Repair; DNA Repair Pathway; DNA Replication Factor; Data; Development; Double Strand Break Repair; Elements; Event; Evolution; Exhibits; Functional disorder; Funding; Genes; Genetic; Genetic Predisposition to Disease; Goals; HTATIP gene; Hereditary Breast and Ovarian Cancer Syndrome; Higher Order Chromatin Structure; Histone H2A; Histones; Human; Hypersensitivity; Immune response; Inflammatory; Knowledge; Laboratories; Length; Malignant Neoplasms; Malignant neoplasm of ovary; Mammalian Cell; Mass Spectrum Analysis; Mediating; Methodology; Mitosis; Modification; Molecular; Nonhomologous DNA End Joining; Nucleosomes; Outcome; Paracrine Communication; Penetrance; Point Mutation; Poly(ADP-ribose) Polymerases; Population Heterogeneity; Post-Translational Protein Processing; Process; Proteins; Publishing; Reporting; Research; Resistance; Role; Signal Pathway; Signal Transduction; System; Tail; Telomere Maintenance; Testing; Time; Tumor Suppression; Ubiquitin; Variant; cancer cell; cancer genome; carcinogenesis; chromatin modification; combinatorial; genome integrity; homologous recombination; inhibitor/antagonist; insight; live cell imaging; loss of function; malignant breast neoplasm; mutant; novel strategies; p53-binding protein 1; prevent; programs; repaired; response; targeted agent; telomere; therapy resistant; tumor

Contact PD/PI: Greenberg, Roger A. Summary DNA repair execution is among the most important determinants of cancer etiology and response to therapy; mandating intimate knowledge of its molecular mechanisms and the vulnerabilities that present when it is altered. Cancer cells frequently harbor changes in their relative utilization (rewiring) of competing DNA repair mechanisms, and this has a profound influence on cancer genome evolution and clinical response to targeted agents. Prominent examples reside in hereditary breast and ovarian cancer syndrome and in a different spectrum of cancers that maintain telomere length through homologous recombination. Germline BRCA1 and BRCA2 gene mutations confer high penetrance breast and ovarian cancer. Both proteins are required for canonical, Rad51 dependent homologous recombination, thus accounting for the increased sensitivity to poly(ADP)ribose polymerase inhibitors (PARPi) exhibited by BRCA null tumors. Unfortunately, less than half of BRCA mutant cancers initially respond to PARPi and resistance invariably emerges in those that do. How DNA repair occurs in the context of BRCA dysfunction is therefore a question of central importance. Some clues exist as to the factors that influence this process. Namely, compelling genetic evidence indicates that hyperactivation of specific chromatin directed DNA repair mechanisms strongly influences genome integrity, cancer etiology, and response to therapy in BRCA mutant cells. To understand the biochemical basis for this phenomenon, my laboratory has developed approaches to identify the full spectrum of combinatorial nucleosome modifications that mediate recognition of damaged chromatin and directs utilization of specific DNA repair mechanisms. Notably, chromatin alterations also underlie the poorly understood phenomenon of alternative telomere lengthening (ALT), an evolutionarily conserved form of telomere maintenance that occurs in nearly 15% of human cancers. We have recently shown that ALT relies on BRCA-Rad51 independent homologous recombination and enacts dramatic changes in higher order chromatin structure to synthesize long telomere tracts in response to double-stranded DNA breaks. This was made possible by our development of methodologies to synchronously activate ALT and visualize every major step encompassing homologous recombination in real time at ALT telomeres. Interestingly, we observe overlapping genetic vulnerabilities in ALT and BRCA mutant cells, suggesting commonality in the repair processes that ensue in each scenario. Our overarching goals are to delineate molecular events necessary for canonical and alternative mechanisms of homologous recombination that arises in the setting of (1) therapeutic resistance in BRCA mutant cells, and (2) during ALT. These objectives will be performed in parallel and with equal emphasis. Our studies will yield fundamental advances to the understanding cancer genome integrity control and clarify new strategies to target underlying vulnerabilities in a broad range of malignancies. !

联系人 PD/PI：Greenberg, Roger A. 概括 DNA 修复执行是癌症病因和治疗反应最重要的决定因素之一； 要求对其分子机制及其改变时出现的脆弱性有深入的了解。 癌细胞对竞争性 DNA 修复的相对利用（重新布线）经常发生变化 机制，这对癌症基因组进化和靶向治疗的临床反应具有深远的影响 代理。突出的例子在于遗传性乳腺癌和卵巢癌综合征以及不同的谱系 通过同源重组维持端粒长度的癌症。种系 BRCA1 和 BRCA2 基因突变导致乳腺癌和卵巢癌的高外显率。这两种蛋白质都是规范所必需的， Rad51 依赖性同源重组，从而解释了对聚 (ADP) 核糖的敏感性增加 BRCA 无效肿瘤表现出聚合酶抑制剂 (PARPi)。不幸的是，只有不到一半的 BRCA 突变 癌症最初对 PARPi 产生反应，并且在那些做出反应的癌症中总是会出现耐药性。 DNA修复是如何发生的 因此，在 BRCA 功能障碍的背景下，这是一个至关重要的问题。存在一些线索 影响这一过程的因素。也就是说，令人信服的遗传证据表明，特定的过度激活 染色质定向 DNA 修复机制强烈影响基因组完整性、癌症病因和反应 BRCA 突变细胞的治疗。为了了解这种现象的生化基础，我的实验室 开发了方法来识别介导的全谱组合核小体修饰 识别受损染色质并指导特定 DNA 修复机制的利用。值得注意的是，染色质 改变也是人们知之甚少的替代端粒延长（ALT）现象的基础，这是一种 端粒维持的进化保守形式，发生在近 15% 的人类癌症中。我们有 最近表明 ALT 依赖于 BRCA-Rad51 独立同源重组并发挥戏剧性作用 响应双链，高阶染色质结构发生变化以合成长端粒束 DNA 断裂。这是通过我们开发同步激活 ALT 和 实时可视化 ALT 端粒上同源重组的每个主要步骤。有趣的是， 我们观察到 ALT 和 BRCA 突变细胞中重叠的遗传脆弱性，表明 每种情况下发生的修复过程。我们的首要目标是描绘分子事件 对于在以下情况下出现的同源重组的规范和替代机制是必要的 (1) BRCA 突变细胞的治疗耐药性，以及 (2) ALT 期间。这些目标将在 并行并同等重视。我们的研究将为理解癌症带来根本性进展 基因组完整性控制并阐明针对​​广泛的潜在漏洞的新策略 恶性肿瘤。 ！