Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA.
Nat Struct Mol Biol. 2013 Mar;20(3):347-54. doi: 10.1038/nsmb.2501. Epub 2013 Feb 10.
Topoisomerase I (TOP1) inhibitors are an important class of anticancer drugs. The cytotoxicity of TOP1 inhibitors can be modulated by replication fork reversal through a process that requires poly(ADP-ribose) polymerase (PARP) activity. Whether regressed forks can efficiently restart and what factors are required to restart fork progression after fork reversal are still unknown. We have combined biochemical and EM approaches with single-molecule DNA fiber analysis to identify a key role for human RECQ1 helicase in replication fork restart after TOP1 inhibition that is not shared by other human RecQ proteins. We show that the poly(ADP-ribosyl)ation activity of PARP1 stabilizes forks in the regressed state by limiting their restart by RECQ1. These studies provide new mechanistic insights into the roles of RECQ1 and PARP in DNA replication and offer molecular perspectives to potentiate chemotherapeutic regimens based on TOP1 inhibition.
拓扑异构酶 I（TOP1）抑制剂是一类重要的抗癌药物。通过需要聚（ADP-核糖）聚合酶（PARP）活性的过程，TOP1 抑制剂的细胞毒性可以被复制叉倒转调节。叉倒转后，叉是否能够有效地重新启动，以及重新启动叉进展需要哪些因素仍然未知。我们已经将生化和 EM 方法与单分子 DNA 纤维分析相结合，以确定人类 RECQ1 解旋酶在 TOP1 抑制后复制叉重新启动中的关键作用，而其他人类 RecQ 蛋白则没有这种作用。我们表明，PARP1 的聚（ADP-核糖）化活性通过限制 RECQ1 对叉的重新启动来稳定倒退的叉。这些研究为 RECQ1 和 PARP 在 DNA 复制中的作用提供了新的机制见解，并为基于 TOP1 抑制的化疗方案提供了分子视角。
