title: Dynamic regulation of histone H3K9 is linked to the switch between replication and transcription at the Dbf4 origin-promoter locus.
abstract: The co-regulation of DNA replication and gene transcription is still poorly understood. To gain a better understanding of this important control mechanism, we examined the DNA replication and transcription using the Dbf4 origin-promoter and Dbf4 pseudogene models. We found that origin firing and Dbf4 transcription activity were inversely regulated in a cell cycle-dependent manner. We also found that proteins critical for the regulation of replication (ORC, MCM), transcription (SP1, TFIIB), and cohesin (Smc1, Smc3) and Mediator functions (Med1, Med12) interact with specific sites within and the surrounding regions of the Dbf4 locus in a cell cycle-dependent manner. As expected, replication initiation occurred within a nucleosome-depleted region, and nucleosomes flanked the 2 replication initiation zones. Further, the histone H3 in this region was distinctly acetylated or trimethylated on lysine 9 in a cell cycle-dependent fluctuation pattern: H3K9ac was most prevalent when the Dbf4 transcription level was highest whereas the H3K9me3 level was greatest during and just after replication. The KDM4A histone demethylase, which is responsible for the H3K9me3 modification, was enriched at the Dbf4 origin in a manner coinciding with H3K9me3. Finally, HP1γ, a protein known to interact with H3K9me3 in the heterochromatin was also found enriched at the origin during DNA replication, indicating that H3K9me3 may be required for the regulation of replication at both heterochromatin and euchromatin regions. Taken together, our data show that mammalian cells employ an extremely sophisticated and multilayered co-regulation mechanism for replication and transcription in a highly coordinated manner.
authors.affiliation: a Tumour Biology Group, Health Sciences North Research Institute , Sudbury , Ontario , Canada.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Kylie
authors.affiliation: a Tumour Biology Group, Health Sciences North Research Institute , Sudbury , Ontario , Canada.
authors.forename: Julia
authors.initials: J
authors.lastname: Romero
authors.affiliation: a Tumour Biology Group, Health Sciences North Research Institute , Sudbury , Ontario , Canada.
authors.forename: Indeewari K S
authors.initials: IK
authors.lastname: Lindamulage
authors.affiliation: a Tumour Biology Group, Health Sciences North Research Institute , Sudbury , Ontario , Canada.
authors.forename: James
authors.initials: J
authors.lastname: Knockleby
authors.affiliation: a Tumour Biology Group, Health Sciences North Research Institute , Sudbury , Ontario , Canada.|b Department of Medicine , Faculty of Medicine, University of Ottawa , Ottawa , Ontario , Canada.
authors.forename: Hoyun
authors.initials: H
authors.lastname: Lee
mesh_terms: D000107:Acetylation; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004261:DNA Replication; D015536:Down-Regulation / Q000235:genetics; D056426:Genetic Loci; D057809:HEK293 Cells; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism*; D006801:Humans; D056484:Jumonji Domain-Containing Histone Demethylases / Q000378:metabolism; D008239:Lysine / Q000378:metabolism*; D056892:Mediator Complex / Q000378:metabolism; D008745:Methylation; D009707:Nucleosomes / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011499:Protein Processing, Post-Translational / Q000235:genetics; D011544:Pseudogenes; D018741:Replication Origin / Q000235:genetics; D014158:Transcription, Genetic; D000097722:Cohesins
chemical_list: D018797:Cell Cycle Proteins; D002843:Chromatin; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone; D006657:Histones; D056484:Jumonji Domain-Containing Histone Demethylases; D008239:Lysine; D056892:Mediator Complex; D009707:Nucleosomes; D000097722:Cohesins; C485678:DBF4 protein, human; C494424:KDM4A protein, human
keywords: ABR; DBF4; DNA replication; H3K9ac; H3K9me3; pseudogene; transcription