Circadian clock feedback cycle through NAMPT-mediated NAD+ biosynthesis.

Department of Medicine, Northwestern University Feinberg School of Medicine, 2200 Campus Drive, Evanston, IL 60208-3500, USA.
Science (Impact Factor: 31.48). 04/2009; 324(5927):651-4. DOI: 10.1126/science.1171641
Source: PubMed

ABSTRACT The circadian clock is encoded by a transcription-translation feedback loop that synchronizes behavior and metabolism with the light-dark cycle. Here we report that both the rate-limiting enzyme in mammalian nicotinamide adenine dinucleotide (NAD+) biosynthesis, nicotinamide phosphoribosyltransferase (NAMPT), and levels of NAD+ display circadian oscillations that are regulated by the core clock machinery in mice. Inhibition of NAMPT promotes oscillation of the clock gene Per2 by releasing CLOCK:BMAL1 from suppression by SIRT1. In turn, the circadian transcription factor CLOCK binds to and up-regulates Nampt, thus completing a feedback loop involving NAMPT/NAD+ and SIRT1/CLOCK:BMAL1.

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