Open AccessRhythmic E-Box Binding by CLK-CYC Controls Daily Cycles in per and tim Transcription and Chromatin Modifications
Author(s) -
Pete Taylor,
Paul E. Hardin
Publication year - 2008
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.01612-07
Subject(s) - biology , chromatin immunoprecipitation , histone h3 , chromatin , transcription (linguistics) , rna polymerase ii , circadian clock , histone , promoter , microbiology and biotechnology , transcription factor , genetics , gene expression , gene , linguistics , philosophy
TheDrosophila melanogaster circadian oscillator comprises interlockedper /tim andClk transcriptional feedback loops. In theper /tim loop, CLK-CYC-dependent transcriptional activation is rhythmically repressed by PER or PER-TIM to control circadian gene expression that peaks around dusk. Here we show that rhythmic transcription ofper andtim involves time-of-day-specific binding of CLK-CYC and associated cycles in chromatin modifications. Activation ofper andtim transcription occurs in concert with CLK-CYC binding to upstream and/or intronic E-boxes, acetylation of histone H3-K9, and trimethylation of histone H3-K4. These events are associated with RNA polymerase II (Pol II) binding to thetim promoter and transcriptional elongation by Pol II that is constitutively bound to theper promoter. Repression ofper andtim transcription is associated with PER-dependent reversal of these events. Rhythms in H3-K9 acetylation and H3-K4 trimethylation are also associated with CLOCK-BMAL1-dependent transcription in mammals, indicating that the mechanism that controls rhythmic transcription is a conserved feature of the circadian clock even though feedback repression is mediated by different proteins.