Differential requirement for H2AX and 53BP1 in organismal development and genome maintenance in the absence of poly(ADP)ribosyl polymerase 1.
Combined deficiencies of poly(ADP)ribosyl polymerase 1 (PARP1) and ataxia telangiectasia mutated (ATM) result in synthetic lethality and, in the mouse, early embryonic death. Here, we investigated the genetic requirements for this lethality via analysis of mice deficient for PARP1 and either of two ATM-regulated DNA damage response (DDR) factors: histone H2AX and 53BP1. We found that, like ATM, H2AX is essential for viability in a PARP1-deficient background. In contrast, deficiency for 53BP1 modestly exacerbates phenotypes of growth retardation, genomic instability, and organismal radiosensitivity observed in PARP1-deficient mice. To gain mechanistic insights into these different phenotypes, we examined roles for 53BP1 in the repair of replication-associated double-strand breaks (DSBs) in several cellular contexts. We show that 53BP1 is required for DNA-PKcs-dependent repair of hydroxyurea (HU)-induced DSBs but dispensable for RPA/RAD51-dependent DSB repair in the same setting. Moreover, repair of mitomycin C (MMC)-induced DSBs and sister chromatid exchanges (SCEs), two RAD51-dependent processes, are 53BP1 independent. Overall, our findings define 53BP1 as a main facilitator of nonhomologous end joining (NHEJ) during the S phase of the cell cycle, beyond highly specialized lymphocyte rearrangements. These findings have important implications for our understanding of the mechanisms whereby ATM-regulated DDR prevents human aging and cancer.
Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Cancer Center, Johns Hopkins University, 1550 Orleans St., CRB II, Room 405, Baltimore, MD 21231, USA.
Benjamin
B
Orsburn
Beatriz
B
Escudero
Mansi
M
Prakash
Silvia
S
Gesheva
Guosheng
G
Liu
David L
DL
Huso
Sonia
S
Franco
D000375:Aging / Q000502:physiology; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone; D004247:DNA / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects / Q000528:radiation effects; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D016678:Genome; D042822:Genomic Instability; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D017404:In Situ Hybridization, Fluorescence; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D016685:Mitomycin / Q000494:pharmacology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010641:Phenotype; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism*; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism; D011839:Radiation, Ionizing; D012854:Sister Chromatid Exchange; D000071857:Tumor Suppressor p53-Binding Protein 1
D002868:Chromosomal Proteins, Non-Histone; D004247:DNA; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D006657:Histones; D006918:Hydroxyurea; D047908:Intracellular Signaling Peptides and Proteins; D016685:Mitomycin; D009687:Nuclear Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D051135:Rad51 Recombinase; D000071857:Tumor Suppressor p53-Binding Protein 1; C498302:Trp53bp1 protein, mouse; C499321:Parp1 protein, mouse; C497264:Prkdc protein, mouse; C475961:gamma-H2AX protein, mouse