Regular cycles of histone acetylation support gene activity in the mammalian body 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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