Methylation gets into rhythm with NAD + -SIRT1

Circadian regulation of epigenetic chromatin marks drives daily transcriptional oscillation of thousands of genes and is intimately linked to cellular metabolism and bioenergetics. New work links circadian fluctuations in the activity of the SIRT1 deacetylase, a sensor of the cellular energy state, to histone-methylation changes and the circadian expression of clock-controlled genes.