Rhythmic histone acetylation underlies transcription in the mammalian circadian clock

Circadian rhythms in H3 histone acetylation are observed in the mouse liver, highlighting their potential role in transcriptional regulation.

• The transcription factors Clock and Bmal1 drive the expression of period and cryptochrome genes in the circadian clock.
• Cry proteins inhibit Clock/Bmal1-mediated transcription without altering their binding to DNA.
• Promoter regions of Per1, Per2, and Cry1 genes show circadian rhythms in H3 histone acetylation and RNA polymerase II binding.
• The histone acetyltransferase p300 interacts with Clock in a time-dependent manner.
• Cry proteins may inhibit p300-induced increases in Clock/Bmal1-mediated transcription.
• The timing of Cry1 mRNA expression is delayed compared to Per rhythms, suggesting a new mechanism for circadian phase control.

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