Xiaohui Lin, Dipika Gupta, Alina Vaitsiankova, Seema Khattri Bhandari, Kay Sze Karina Leung, Demis Menolfi, Brian J. Lee, Helen R. Russell, Steven Gershik, Xiaoyu Huang, Wei Gu, Peter J. McKinnon, Françoise Dantzer, Eli Rothenberg, Alan E. Tomkinson, Shan Zha
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引用次数: 0
Abstract
Poly (ADP-ribose) polymerase (PARP) 1 and 2 enzymatic inhibitors (PARPi) are promising cancer treatments. But recently, their use has been hindered by unexplained severe anemia and treatment-related leukemia. In addition to enzymatic inhibition, PARPi also trap PARP1 and 2 at DNA lesions. Here we report that, unlike Parp2−/− mice, which develop normally, mice expressing catalytically inactive Parp2 (E534A and Parp2EA/EA) succumb to Tp53- and Chk2-dependent erythropoietic failure in utero, mirroring Lig1−/− mice. While DNA damage mainly activates PARP1, we demonstrate that DNA replication activates PARP2 robustly. PARP2 is selectively recruited and activated by 5′-phosphorylated nicks (5′p-nicks), including those between Okazaki fragments, resolved by ligase 1 (Lig1) and Lig3. Inactive PARP2, but not its active form or absence, impedes Lig1- and Lig3-mediated ligation, causing dose-dependent replication fork collapse, which is detrimental to erythroblasts with ultra-fast forks. This PARylation-dependent structural function of PARP2 at 5′p-nicks explains the detrimental effects of PARP2 inactivation on erythropoiesis, shedding light on PARPi-induced anemia and the selection for TP53/CHK2 loss.
期刊介绍:
Molecular Cell is a companion to Cell, the leading journal of biology and the highest-impact journal in the world. Launched in December 1997 and published monthly. Molecular Cell is dedicated to publishing cutting-edge research in molecular biology, focusing on fundamental cellular processes. The journal encompasses a wide range of topics, including DNA replication, recombination, and repair; Chromatin biology and genome organization; Transcription; RNA processing and decay; Non-coding RNA function; Translation; Protein folding, modification, and quality control; Signal transduction pathways; Cell cycle and checkpoints; Cell death; Autophagy; Metabolism.