title: Circadian clock regulates dynamic chromatin modifications associated with Arabidopsis CCA1/LHY and TOC1 transcriptional rhythms.
abstract: Circadian clocks enable organisms to adapt to a 24 h diurnal cycle and anticipate rhythmic changes in the environment. The Arabidopsis central oscillator contains three genes encoding core clock components. CIRCADIAN CLOCK ASSOCIATED 1 (CCA1)/LATE ELONGATED HYPOCOTYL (LHY) and TIMING OF CAB EXPRESSION 1 (TOC1) reciprocally repress genes encoding each other and are critical for the generation of circadian rhythms controlling many clock outputs. A precise regulation of transcriptional events is, therefore, essential for proper circadian function. Here, we investigated histone 3 (H3) tail modifications of CCA1, LHY and TOC1 under various conditions. We found specific association of only H3K4Me3 and H3K9/14Ac with the translational start site of these three genes. These H3 marks were enriched at circadian time points of their increased transcription at different photoperiods and under free-running conditions, suggesting circadian regulation of H3 modifications. Analysis of clock-compromised CCA1-overexpressing lines provided evidence that light/dark photoperiods signal the establishment of these chromatin changes which are gated by the clock.
authors.affiliation: Laboratory of Plant Molecular Biology, The Rockefeller University, New York, NY 10065-6399, USA.
authors.forename: Hans
authors.initials: H
authors.lastname: Hemmes
authors.forename: Rossana
authors.initials: R
authors.lastname: Henriques
authors.forename: In-Cheol
authors.initials: IC
authors.lastname: Jang
authors.forename: Sanghee
authors.initials: S
authors.lastname: Kim
authors.forename: Nam-Hai
authors.initials: NH
authors.lastname: Chua
mesh_terms: D000107:Acetylation; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002843:Chromatin / Q000235:genetics / Q000378:metabolism*; D057906:Circadian Clocks / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D003624:Darkness; D018506:Gene Expression Regulation, Plant; D006657:Histones / Q000235:genetics / Q000378:metabolism; D008027:Light; D008745:Methylation; D008954:Models, Biological; D009154:Mutation; D017440:Photoperiod; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; D002843:Chromatin; D004268:DNA-Binding Proteins; D006657:Histones; C113192:LHY protein, Arabidopsis; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors