Natural rhythms in mammalian physiology and behaviour are set in the brain by the daily light–dark cycle. But in some organs, the circadian clock can be set by nutrient availability — possibly allowing optimal timing of metabolic processes.
Ronald Evans at the Salk Institute for Biological Studies in La Jolla, California, Craig Thompson at the University of Pennsylvania in Philadelphia and their colleagues have identified how nutrient levels influence these light-independent clocks. They found that, in mouse livers, expression of one component of the enzyme AMPK, a nutrient-sensitive metabolic regulator, is cyclical. In addition, AMPK initiates the destruction of cryptochrome 1, a key part of the circadian clock.
Mice in which AMPK signalling was disrupted had altered circadian rhythms.
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Biochemistry: Hungry circadian clock. Nature 461, 1030 (2009). https://doi.org/10.1038/4611030d
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DOI: https://doi.org/10.1038/4611030d
