Iraia García-Santisteban1,2, Alba Llopis2, Lenno Krenning2, Jon Vallejo-Rodríguez1, Bram van den Broek2, Ana M Zubiaga3, René H Medema4. 1. Department of Genetics, Physical Anthropology and Animal Physiology, University of the Basque Country (UPV/EHU), B/Sarriena s/n, 48940, Leioa, Basque Country, Spain. 2. Oncode Institute, Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066, CX, Amsterdam, The Netherlands. 3. Department of Genetics, Physical Anthropology and Animal Physiology, University of the Basque Country (UPV/EHU), B/Sarriena s/n, 48940, Leioa, Basque Country, Spain. ana.zubiaga@ehu.eus. 4. Oncode Institute, Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066, CX, Amsterdam, The Netherlands. r.medema@nki.nl.
Abstract
BACKGROUND: The G1 checkpoint is a critical regulator of genomic stability in untransformed cells, preventing cell cycle progression after DNA damage. DNA double-strand breaks (DSBs) recruit and activate ATM, a kinase which in turn activates the CHK2 kinase to establish G1 arrest. While the onset of G1 arrest is well understood, the specific role that ATM and CHK2 play in regulating G1 checkpoint maintenance remains poorly characterized. RESULTS: Here we examine the impact of ATM and CHK2 activities on G1 checkpoint maintenance in untransformed cells after DNA damage caused by DSBs. We show that ATM becomes dispensable for G1 checkpoint maintenance as early as 1 h after DSB induction. In contrast, CHK2 kinase activity is necessary to maintain the G1 arrest, independently of ATM, ATR, and DNA-PKcs, implying that the G1 arrest is maintained in a lesion-independent manner. Sustained CHK2 activity is achieved through auto-activation and its acute inhibition enables cells to abrogate the G1-checkpoint and enter into S-phase. Accordingly, we show that CHK2 activity is lost in cells that recover from the G1 arrest, pointing to the involvement of a phosphatase with fast turnover. CONCLUSION: Our data indicate that G1 checkpoint maintenance relies on CHK2 and that its negative regulation is crucial for G1 checkpoint recovery after DSB induction.
BACKGROUND: The G1 checkpoint is a critical regulator of genomic stability in untransformed cells, preventing cell cycle progression after DNA damage. DNA double-strand breaks (DSBs) recruit and activate ATM, a kinase which in turn activates the CHK2 kinase to establish G1 arrest. While the onset of G1 arrest is well understood, the specific role that ATM and CHK2 play in regulating G1 checkpoint maintenance remains poorly characterized. RESULTS: Here we examine the impact of ATM and CHK2 activities on G1 checkpoint maintenance in untransformed cells after DNA damage caused by DSBs. We show that ATM becomes dispensable for G1 checkpoint maintenance as early as 1 h after DSB induction. In contrast, CHK2 kinase activity is necessary to maintain the G1 arrest, independently of ATM, ATR, and DNA-PKcs, implying that the G1 arrest is maintained in a lesion-independent manner. Sustained CHK2 activity is achieved through auto-activation and its acute inhibition enables cells to abrogate the G1-checkpoint and enter into S-phase. Accordingly, we show that CHK2 activity is lost in cells that recover from the G1 arrest, pointing to the involvement of a phosphatase with fast turnover. CONCLUSION: Our data indicate that G1 checkpoint maintenance relies on CHK2 and that its negative regulation is crucial for G1 checkpoint recovery after DSB induction.
Authors: Lenno Krenning; Femke M Feringa; Indra A Shaltiel; Jeroen van den Berg; René H Medema Journal: Mol Cell Date: 2014-06-05 Impact factor: 17.970
Authors: Hung Yi Kristal Kaan; Johanna Weiss; Dominik Menger; Venkatasubramanian Ulaganathan; Katarzyna Tkocz; Christian Laggner; Florence Popowycz; Benoît Joseph; Frank Kozielski Journal: J Med Chem Date: 2011-02-23 Impact factor: 7.446