Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.


Sci. Signal., 5 May 2009
Vol. 2, Issue 69, p. ec157
[DOI: 10.1126/scisignal.269ec157]


Circadian Rhythms Circadian Oscillations

Guy Riddihough

Science, AAAS, Washington, DC 20005, USA

The 24-hour day-night cycle plays an important role in mammalian physiology and behavior, and, as most travelers are well aware, there is an intimate link between our built-in circadian clocks and metabolic rhythms. This link is in part forged by the protein deacetylase SIRT1, which regulates the clock’s molecular circuitry. SIRT1 uses as a cofactor the cellular metabolite NAD+, which is synthesized through a salvage pathway that includes the enzyme nicotinamide phosphoribosyltransferase (NAMPT) (see the Perspective by Wijnen). Ramsey et al. and Nakahata et al. now show that NAMPT and NAD+ levels oscillate during the daily 24-hour cycle and that this oscillation is regulated by the circadian clock. Furthermore, the oscillations in NAD+ modulate the activity of SIRT1 feeding back into the circadian clock.

K. M. Ramsey, J. Yoshino, C. S. Brace, D. Abrassart, Y. Kobayashi, B. Marcheva, H.-K. Hong, J. L. Chong, E. D. Buhr, C. Lee, J. S. Takahashi, S. Imai, J. Bass, Circadian clock feedback cycle through NAMPT-mediated NAD+ biosynthesis. Science 324, 651–654 (2009). [Abstract] [Full Text]

Y. Nakahata, S. Sahar, G. Astarita, M. Kaluzova, P. Sassone-Corsi, Circadian control of the NAD+ salvage pathway by CLOCK-SIRT1. Science 324, 654–657 (2009). [Abstract] [Full Text]

H. Wijnen, A circadian loop asSIRTs itself. Science 324, 598–599 (2009). [Summary] [Full Text]

Citation: G. Riddihough, Circadian Oscillations. Sci. Signal. 2, ec157 (2009).

To Advertise     Find Products

Science Signaling. ISSN 1937-9145 (online), 1945-0877 (print). Pre-2008: Science's STKE. ISSN 1525-8882