Studying the mechanisms underlying the protection of common fragile sites and structure-prone DNA sequences

首席研究员：吴晓华 项目概要 研究保护常见脆弱地点和结构的机制 易发生的DNA序列 项目概要/摘要 常见脆弱位点 (CFS) 是大的染色体区域，经常表现出间隙和 复制应激时中期染色体断裂。结构倾向丰富的 AT 序列 CFS 中的存在 (CFS-AT) 会导致 CFS 不稳定。除了 CFS-AT 之外，还有其他结构倾向 DNA 序列，例如 G-四链体 (G4s)，在人类基因组中也很丰富，并且 与癌症中的染色体重排断点有关。由于 CFS 和许多 易于结构的 DNA 序列，包括 G4，是正常染色体结构的一部分，它是 了解这些易于结构的 DNA 序列的完整性如何在 哺乳动物细胞。在此拨款申请中，我们将使用基于 EGFP 的 DSB 修复报告器 研究保护易结构 DNA 序列的潜在机制 CFS 和 G4。我们将研究染色质重塑在维持 CFS 和 解决 DSB 修复机制，专门用于修复 DNA 次级产生的 DSB 叉子塌陷时的结构。我们还将探索相关途径的功能协调 保护易于结构的 DNA 序列免受 DSB 形成以及修复生成的 DSB 当叉在易于结构的 DNA 序列处塌陷时。此外，我们将研究失配如何 修复 (MMR) 蛋白有助于保持易出现结构的 DNA 序列的完整性。我们的研究 将产生对维持 CFS 完整性的潜在机制的分子见解 和其他易于结构的 DNA 序列。这些研究也将为 开发新的靶向癌症治疗策略。

Principal Investigator: Wu, Xiaohua Project Summary Studying the mechanisms underlying the protection of common fragile sites and structure- prone DNA sequences Project Summary/Abstract Common fragile sites (CFSs) are large chromosomal regions that often exhibit gaps and breaks on metaphase chromosomes upon replication stress. Structure-prone AT-rich sequences present at CFSs (CFS-ATs) contribute to CFS instability. Besides CFS-ATs, other structure-prone DNA sequences, such as G-quadruplexes (G4s), are also abundant in the human genome and are associated with chromosomal rearrangement breakpoints in cancer. Since CFSs and many structure-prone DNA sequences, including G4s, are part of normal chromosomal structures, it is important to understand how the integrity of these structure-prone DNA sequences is maintained in mammalian cells. In this grant application, we will use EGFP-based DSB repair reporters to investigate the mechanisms underlying the protection of structure-prone DNA sequences present at CFSs and G4s. We will study the role of chromatin-remodeling in the maintenance of CFSs and address the DSB repair mechanism specifically used to repair DSBs arising at DNA secondary structures upon fork collapse. We will also explore the functional coordination of pathways involved in protecting structure-prone DNA sequences from DSB formation and in repairing DSBs generated upon fork collapse at structure-prone DNA sequences. Furthermore, we will study how mismatch repair (MMR) proteins help preserve the integrity of structure-prone DNA sequences. Our studies will yield molecular insights into the mechanisms underlying the maintenance of the integrity of CFS and other structure-prone DNA sequences. These studies will also lay the groundwork for development of new targeted cancer treatment strategies.