The role of SWI/SNF chromatin remodelers in homologous recombination and genome stability

SWI/SNF 染色质重塑剂在同源重组和基因组稳定性中的作用

• 批准号: 10515147
• 负责人: Renier Velez-Cruz
• 金额: $ 44.93万
• 依托单位: MIDWESTERN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-10 至 2025-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10515147
• 关键词: ARID1A gene; ATP phosphohydrolase; Affect; Agreement; Award; Biology; Breast Cancer Cell; Cells; Chromatin; Chromatin Remodeling Factor; Complex; Core Protein; DNA; DNA Damage; DNA Double Strand Break; DNA Repair; Data; Defect; Double Strand Break Repair; E2F transcription factors; Environment; Excision; Family; Fostering; Future; Generations; Genes; Genome Stability; Genomic Instability; Goals; Human; Impairment; Link; Malignant Neoplasms; Malignant neoplasm of lung; Malignant neoplasm of ovary; Malignant neoplasm of pancreas; Motivation; Mutate; Mutation; Nucleosomes; Pathway interactions; Play; Poly(ADP-ribose) Polymerases; Polymerase; Regimen; Research; Role; SMARCA4 gene; SWI/SNF Family Complex; Science; Signal Transduction; Single-Stranded DNA; Site; Slide; Students; Testing; Therapeutic; Transcription Coactivator; Transcriptional Regulation; Tumor Suppression; Tumor Suppressor Proteins; Work; cancer therapy; cancer type; carcinogenesis; career; chemotherapeutic agent; chromatin remodeling; density; design; experience; homologous recombination; improved; inhibitor; malignant breast neoplasm; mutant; novel; nuclease; osteosarcoma; recruit; repair function; therapy development

Multiple subunits of the SWI/SNF chromatin remodeling complexes have been identified as a novel class of tumor suppressors mutated in up to 20% of human cancers, but their mechanism of tumor suppression is still poorly understood. These complexes are composed of a mutually exclusive ATPase subunit (either BRG1 or BRM), a set of core factors, and a group of accessory subunits. SWI/SNF complexes were first identified as transcriptional activators and therefore most of the research efforts have been focused on the role of these ATPases in the transcriptional regulation of a variety of cellular pathways involved in carcinogenesis. More recent work has linked BRG1 to DNA repair. We identified a complex containing TopBP1-E2F1-RB responsible for the recruitment of BRG1 to DNA double strand breaks (DSBs). Moreover, we also identified a function for BRG1 stimulating DNA end resection and homologous recombination (HR) by reducing nucleosome density at DSBs and promoting the recruitment of the CtIP nuclease. However, the role that the other ATPase (BRM) and other non-catalytic subunits of the SWI/SNF complex may play in this function is still unknown. The goal of this proposal is to further define the mechanism by which BRG1 and BRM stimulate DNA end resection and HR, to determine to what extent SWI/SNF subunits ARID1A and BRD7 are required for this function, and to test whether we can sensitize breast cancer cells to chemotherapeutic agents by inactivating these SWI/SNF subunits. Our hypothesis is that BRG1 reduces nucleosome density at DSBs, thus allowing the recruitment of the DNA end resection nuclease CtIP and stimulating DNA end resection and HR, and that ARID1A and BRD7 are important for anchoring these complexes at DSBs. The uncovering of a function in DSB repair for SWI/SNF accessory subunits could help explain their tumor suppressor activities. Moreover, identifying multiple SWI/SNF subunits required for HR, would also identify a DNA repair vulnerability that could be exploited therapeutically against SWI/SNF-mutated cancers. In order to test this hypothesis, we will, first, determine whether a BRG1- or BRM- ATPase-dead mutant would be able to stimulate DNA end resection and promote the recruitment of the CtIP nuclease. Second, we will define the role non-catalytic SWI/SNF subunits ARID1A and BRD7 play in the recruitment of BRG1, chromatin remodeling at DSBs, DNA end resection, and HR, by analyzing the generation of single-stranded DNA and ATR signaling after DNA damage. Third, we will determine whether we can sensitize breast cancer cells to chemotherapeutic agents, including Poly (ADP-ribose) polymerase (PARP) inhibitors, by inactivating BRG1, BRM, ARID1A, and BRD7 subunits. This systematic study of the function of the SWI/SNF subunits in DNA end resection and HR will further our understanding of the biology of these complexes, their functions, and the required composition of these complexes in order to perform this function in HR. Moreover, we could potentially identify DNA repair vulnerabilities in SWI/SNF-mutated cancers that could be exploited through specific chemotherapeutic regimens designed for HR-deficient malignancies.

SWI/SNF染色质重塑复合物的多个亚基已被鉴定为一类新的染色质重塑复合物。 肿瘤抑制因子在高达20%的人类癌症中发生突变，但它们的肿瘤抑制机制仍然是未知的。 不太了解。这些复合物由相互排斥的ATP酶亚基（BRG 1或BRG 2）组成。 BRM）、一组核心因子和一组辅助亚基。SWI/SNF复合物首先被鉴定为 转录激活因子，因此大多数研究工作都集中在这些转录激活因子的作用上。 三磷酸腺苷酶在参与癌发生的多种细胞通路的转录调节中的作用。最近 这项研究将BRG 1与DNA修复联系起来。我们鉴定了一种含有TopBP 1-E2 F1-RB的复合物，该复合物负责 BRG 1的募集导致DNA双链断裂（DSB）。此外，我们还确定了BRG 1的功能 通过降低DSB处的核小体密度来刺激DNA末端切除和同源重组（HR） 并促进CtIP核酸酶的募集。然而，其他ATP酶（BRM）和其他 SWI/SNF复合物的非催化亚基可能在该功能中起作用仍然是未知的。这项提案的目的是 进一步确定BRG 1和BRM刺激DNA末端切除和HR的机制，以确定 SWI/SNF亚基ARID 1A和BRD 7在多大程度上需要这种功能，并测试我们是否可以 通过灭活这些SWI/SNF亚基使乳腺癌细胞对化疗剂敏感。我们 假设BRG 1降低了DSB处的核小体密度，从而允许DNA末端的募集 切除核酸酶CtIP和刺激DNA末端切除和HR，以及ARID 1A和BRD 7是重要的 用于将这些复合物锚定在DSB上。SWI/SNF附件DSB修复功能的发现 亚基可以帮助解释它们的肿瘤抑制活性。此外，鉴定多个SWI/SNF亚基， HR所需的，也将确定一个DNA修复的脆弱性，可以利用治疗， SWI/SNF突变的癌症。为了检验这一假设，我们将首先确定BRG 1-或BRM- ATP酶死亡突变体能够刺激DNA末端切除并促进CtIP的募集 核酸酶。其次，我们将定义非催化SWI/SNF亚基ARID 1A和BRD 7在细胞凋亡中的作用。 BRG 1的募集、DSB处的染色质重塑、DNA末端切除和HR，通过分析 单链DNA和DNA损伤后的ATR信号。第三，我们将确定我们是否能使 乳腺癌细胞与化疗剂，包括聚（ADP-核糖）聚合酶（PARP）抑制剂， 使BRG 1、BRM、ARID 1A和BRD 7亚基失活。对SWI/SNF功能的系统研究 DNA末端切除和HR中的亚基将进一步加深我们对这些复合物生物学的理解， 功能，以及这些复合物的所需组成，以便在HR中执行此功能。此外， 我们有可能发现SWI/SNF突变癌症中的DNA修复漏洞， 通过为HR缺陷的恶性肿瘤设计的特定化疗方案。