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]

The editors suggest the following Related Resources on Science sites:

In Science Signaling

EDITORS' CHOICE
Circadian Rhythms
Free from Transcription

John F. Foley (1 February 2011)
Sci. Signal. 4 (158), ec29. [DOI: 10.1126/scisignal.4158ec29]
 |  Abstract »

PERSPECTIVES
Circadian Rhythms
Entrainment of the Drosophila Circadian Clock: More Heat Than Light

Jin-Yuan Fan, Michael J. Muskus, and Jeffrey L. Price (20 November 2007)
Sci. STKE 2007 (413), pe65. [DOI: 10.1126/stke.4132007pe65]
 |  Abstract »  |  Full Text »  |  PDF »

TEACHING RESOURCES
STKE Teaching Resources
Oscillatory Mechanisms Underlying the Murine Circadian Clock

Russell N. Van Gelder and Erik D. Herzog (18 November 2003)
Sci. STKE 2003 (209), tr7. [DOI: 10.1126/stke.2092003tr7]
 |  Abstract »  |  Resource Details »

CONNECTIONS MAP OVERVIEWS
STKE Connections Map Overview
Circadian Rhythms in the Mouse: A Connections Map

Russell N. Van Gelder (5 August 2003)
Sci. STKE 2003 (194), cm9. [DOI: 10.1126/scisignal.1942003cm9]
 |  Abstract »  |  Pathway »  |  Animation »