title: Methylation of histone H4 lysine 20 by PR-Set7 ensures the integrity of late replicating sequence domains in Drosophila.
abstract: The methylation state of lysine 20 on histone H4 (H4K20) has been linked to chromatin compaction, transcription, DNA repair and DNA replication. Monomethylation of H4K20 (H4K20me1) is mediated by the cell cycle-regulated histone methyltransferase PR-Set7. PR-Set7 depletion in mammalian cells results in defective S phase progression and the accumulation of DNA damage, which has been partially attributed to defects in origin selection and activation. However, these studies were limited to only a handful of mammalian origins, and it remains unclear how PR-Set7 and H4K20 methylation impact the replication program on a genomic scale. We employed genetic, cytological, and genomic approaches to better understand the role of PR-Set7 and H4K20 methylation in regulating DNA replication and genome stability in Drosophila cells. We find that deregulation of H4K20 methylation had no impact on origin activation throughout the genome. Instead, depletion of PR-Set7 and loss of H4K20me1 results in the accumulation of DNA damage and an ATR-dependent cell cycle arrest. Coincident with the ATR-dependent cell cycle arrest, we find increased DNA damage that is specifically limited to late replicating regions of the Drosophila genome, suggesting that PR-Set7-mediated monomethylation of H4K20 is critical for maintaining the genomic integrity of late replicating domains.
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Yulong
authors.initials: Y
authors.lastname: Li
authors.affiliation: Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: Robin L
authors.initials: RL
authors.lastname: Armstrong
authors.affiliation: Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA Departments of Biology and Genetics, Lineberger Comprehensive Cancer Center, and Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Duronio
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA david.macalpine@duke.edu.
authors.forename: David M
authors.initials: DM
authors.lastname: MacAlpine
mesh_terms: D000818:Animals; D059447:Cell Cycle Checkpoints; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D004249:DNA Damage; D004261:DNA Replication; D042522:DNA Replication Timing; D029721:Drosophila Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics* / Q000378:metabolism*; D049750:Genome, Insect / Q000235:genetics; D042822:Genomic Instability; D011495:Histone-Lysine N-Methyltransferase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism*; D008745:Methylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D018741:Replication Origin; D016196:S Phase
chemical_list: D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; D006657:Histones; D011495:Histone-Lysine N-Methyltransferase; C498199:PR-Set7 protein, Drosophila; C444435:Mei-41 protein, Drosophila; D017346:Protein Serine-Threonine Kinases; D008239:Lysine