title: Temporal association of ORCA/LRWD1 to late-firing origins during G1 dictates heterochromatin replication and organization.
abstract: DNA replication requires the recruitment of a pre-replication complex facilitated by Origin Recognition Complex (ORC) onto the chromatin during G1 phase of the cell cycle. The ORC-associated protein (ORCA/LRWD1) stabilizes ORC on chromatin. Here, we evaluated the genome-wide distribution of ORCA using ChIP-seq during specific time points of G1. ORCA binding sites on the G1 chromatin are dynamic and temporally regulated. ORCA association to specific genomic sites decreases as the cells progressed towards S-phase. The majority of the ORCA-bound sites represent replication origins that also associate with the repressive chromatin marks H3K9me3 and methylated-CpGs, consistent with ORCA-bound origins initiating DNA replication late in S-phase. Further, ORCA directly associates with the repressive marks and interacts with the enzymes that catalyze these marks. Regions that associate with both ORCA and H3K9me3, exhibit diminished H3K9 methylation in ORCA-depleted cells, suggesting a role for ORCA in recruiting the H3K9me3 mark at certain genomic loci. Similarly, DNA methylation is altered at ORCA-occupied sites in cells lacking ORCA. Furthermore, repressive chromatin marks influence ORCA's binding on chromatin. We propose that ORCA coordinates with the histone and DNA methylation machinery to establish a repressive chromatin environment at a subset of origins, which primes them for late replication.
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801, USA.
authors.forename: Yating
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801, USA.
authors.forename: Abid
authors.initials: A
authors.lastname: Khan
authors.affiliation: Developmental Therapeutics Branch, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, USA.
authors.forename: Anna B
authors.initials: AB
authors.lastname: Marks
authors.affiliation: Developmental Therapeutics Branch, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, USA.
authors.forename: Owen K
authors.initials: OK
authors.lastname: Smith
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801, USA.
authors.forename: Sumanprava
authors.initials: S
authors.lastname: Giri
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801, USA.
authors.forename: Yo-Chuen
authors.initials: YC
authors.lastname: Lin
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Creager
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: MacAlpine
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801, USA.
authors.forename: Kannanganattu V
authors.initials: KV
authors.lastname: Prasanth
authors.affiliation: Developmental Therapeutics Branch, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, USA.
authors.forename: Mirit I
authors.initials: MI
authors.lastname: Aladjem
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801, USA.
authors.forename: Supriya G
authors.initials: SG
authors.lastname: Prasanth
mesh_terms: D001665:Binding Sites; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D018899:CpG Islands; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D019175:DNA Methylation; D004261:DNA Replication; D016193:G1 Phase / Q000235:genetics*; D006570:Heterochromatin / Q000378:metabolism*; D042421:Histone Code; D006801:Humans; D008868:Microtubule Proteins / Q000378:metabolism*; D018741:Replication Origin
chemical_list: D002843:Chromatin; D006570:Heterochromatin; C000595278:LRWD1 protein, human; D008868:Microtubule Proteins; D004248:DNA (Cytosine-5-)-Methyltransferases