Gyula Timinszky, Sébastien Huet, Catherine Chapuis, Hari R. Singh, Rebecca Smith, Hafida Sellou, M. Kozlowski, Andreas G. Ladurner, Sebastian Bultmann, Théo Lebeaupin, Anna Hegele, Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), Department of Physiological Chemistry, Butenandt Institute and Biomedical Center-Ludwig Maximilians University of Munich, Department of Biology II - Neurobiology Biocenter, Ludwig-Maximilians-Universität München (LMU), We thank the Microscopy Rennes Imaging Center (BIOSIT, Université Rennes 1) for technical assistance. This work was supported by the Agence National de la Recherche (JCJC-SVSE2-2011, ChromaTranscript project to S.H.), the Ligue contre le Cancer du Grand-Ouest (commitees 35 and 72 to S.H.), the European Union (FP7-PEOPLE-2011-CIG, ChromaTranscript project to S.H., and Marie Curie Initial Training Network, Nucleosome4D to A.G.L.), the Deutsche Forschungsgemeinschaft (TI 817/2-1 to G.T., and SFB collaborative research center 1064 to A.G.L.), and Worldwide Cancer Research (14-1315 to G.T.). H.S.’s PhD fellowship was funded by the Centre National de la Recherche Scientifique and the Région Bretagne. Our collaboration benefited from funding from the Hubert Curien partnership/German Academic Exchange Service–DAAD (28486ZD to S.H., 55934632 to G.T.) and the Deutsche Forschungsgemeinschaft CIPSM and SyNergy excellence clusters (to A.G.L.)., Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), and Butenandt Institute and Biomedical Center-Ludwig-Maximilians University [Munich] (LMU)
PARP1 and its effector, the ATP-dependent chromatin remodeler Alc1/Chd1L, are identified as key players during the rapid chromatin relaxation at DNA damage sites., Chromatin relaxation is one of the earliest cellular responses to DNA damage. However, what determines these structural changes, including their ATP requirement, is not well understood. Using live-cell imaging and laser microirradiation to induce DNA lesions, we show that the local chromatin relaxation at DNA damage sites is regulated by PARP1 enzymatic activity. We also report that H1 is mobilized at DNA damage sites, but, since this mobilization is largely independent of poly(ADP-ribosyl)ation, it cannot solely explain the chromatin relaxation. Finally, we demonstrate the involvement of Alc1, a poly(ADP-ribose)- and ATP-dependent remodeler, in the chromatin-relaxation process. Deletion of Alc1 impairs chromatin relaxation after DNA damage, while its overexpression strongly enhances relaxation. Altogether our results identify Alc1 as an important player in the fast kinetics of the NAD+- and ATP-dependent chromatin relaxation upon DNA damage in vivo.