Description
Circadian clocks are cell-autonomous oscillators regulating daily rhythms in a wide range of physiological, metabolic and behavioral processes. Conversely, metabolic signals such as redox state, NAD+/NADH and AMP/ADP ratios or heme feed back to and modulate circadian mechanisms to optimize energy utilization across the 24-hour cycle. We show that the signaling molecule carbon monoxide (CO) generated by rhythmic heme degradation is required for normal circadian rhythms as well as circadian metabolic outputs.