Phosphorylation of EXO1 by CDKs 1 and 2 regulates DNA end resection and repair pathway choice.
Resection of DNA double-strand breaks (DSBs) is a pivotal step during which the choice between NHEJ and HR DNA repair pathways is made. Although CDKs are known to control initiation of resection, their role in regulating long-range resection remains elusive. Here we show that CDKs 1/2 phosphorylate the long-range resection nuclease EXO1 at four C-terminal S/TP sites during S/G2 phases of the cell cycle. Impairment of EXO1 phosphorylation attenuates resection, chromosomal integrity, cell survival and HR, but augments NHEJ upon DNA damage. In contrast, cells expressing phospho-mimic EXO1 are proficient in resection even after CDK inhibition and favour HR over NHEJ. Mutation of cyclin-binding sites on EXO1 attenuates CDK binding and EXO1 phosphorylation, causing a resection defect that can be rescued by phospho-mimic mutations. Mechanistically, phosphorylation of EXO1 augments its recruitment to DNA breaks possibly via interactions with BRCA1. In summary, phosphorylation of EXO1 by CDKs is a novel mechanism regulating repair pathway choice.
Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC7, 214E, Dallas, Texas 75390, USA.
Nozomi
N
Tomimatsu
Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC7, 214E, Dallas, Texas 75390, USA.
Bipasha
B
Mukherjee
Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC7, 214E, Dallas, Texas 75390, USA.
Molly
M
Catherine Hardebeck
Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC7, 214E, Dallas, Texas 75390, USA.
Mariya
M
Ilcheva
1] Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC7, 214E, Dallas, Texas 75390, USA [2].
Cristel
C
Vanessa Camacho
Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland 4029, Australia.
Janelle
J
Louise Harris
Deparment of Pediatrics, Stanford University, Stanford, California 94395, USA.
Matthew
M
Porteus
CRCM, Inserm, U1068; Institut Paoli-Calmettes; Aix-Marseille Université, UM 105; CNRS, UMR7258, Marseille F-13009, France.
Bertrand
B
Llorente
Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland 4029, Australia.
Kum Kum
KK
Khanna
Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC7, 214E, Dallas, Texas 75390, USA.
Sandeep
S
Burma
D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D051357:Cyclin-Dependent Kinase 2 / Q000235:genetics / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage / Q000235:genetics / Q000502:physiology; D004260:DNA Repair / Q000235:genetics / Q000502:physiology; D045643:DNA Repair Enzymes / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D047468:Immunoprecipitation; D010766:Phosphorylation / Q000235:genetics / Q000502:physiology*
D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; C114331:EXO1 protein, human; D005090:Exodeoxyribonucleases; D045643:DNA Repair Enzymes