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. Author manuscript; available in PMC: 2013 Jul 1.
Published in final edited form as: Trends Endocrinol Metab. 2012 Mar 16;23(7):312–318. doi: 10.1016/j.tem.2012.02.003

Figure 1. Circadian control of NAD+ and NAD+-dependent enzymes.

Figure 1

The core circadian clock is composed of a feedback loop involving a series of activators (CLOCK/BMAL1) and repressors (CRYs/PERs) that generate ~24h rhythms of gene transcription. Targets of the circadian clock include genes involved in the production and utilization of nutrient metabolites, including the NAD+ biosynthetic enzyme NAMPT. NAD+ is an important cofactor for the metabolic regulators, SIRT1, SIRT3–5 and PARP1, which may mediate rhythms of oxidative metabolism.