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Sci. STKE, 18 December 2007
Vol. 2007, Issue 417, p. tw460
[DOI: 10.1126/stke.4172007tw460]

EDITORS' CHOICE

Biochemistry Circadian Rhythm Methods

L. Bryan Ray1 and Pamela J. Hines2

1Science, Science’s STKE, AAAS, Washington, DC 20005, USA
2Science, AAAS, Washington, DC 20005, USA

Circadian rhythms in plants and animals appear to be coupled to periodic changes in activity of metabolic pathways (see the Perspective by Imaizumi et al.). Yin et al. describe a molecular mechanism that may contribute to the coordination of these biochemical processes. Rev-erb{alpha} controls transcription of the gene encoding the circadian clock component Bmal1. Rev-erb{alpha} binds to and is regulated by heme, which stabilizes Rev-erb{alpha} in a repressor complex, which in turn can block production of gluconeogenic enzymes. Thus, Rev-erb{alpha} acts as a heme sensor to coordinate the cellular clock, glucose homeostasis, and energy metabolism in human liver cells. Studying Arabidopsis, Dodd et al. now show that a cytoplasmic signaling molecule, cyclic adenosine diphosphate ribose (cADPR), is also a component of the clock mechanism. Perturbations to the feedback loop including cADPR result in instabilities in the clock and disruptions in the daily oscillations of cytoplasmic Ca2+ release.

L. Yin, N. Wu, J. C. Curtin, M. Qatanani, N. R. Szwergold, R. A. Reid, G. M. Waitt, D. J. Parks, K. H. Pearce, G. B. Wisely, M. A. Lazar, Rev-erb{alpha}, a heme sensor that coordinates metabolic and circadian pathways. Science 318, 1786-1789 (2007). [Abstract] [Full Text]

A. N. Dodd, M. J. Gardner, C. T. Hotta, K. E. Hubbard, N. Dalchau, J. Love, J.-M. Assie, F. C. Robertson, M. K. Jakobsen, J. Gonçalves, D. Sanders, A. A. R. Webb, The Arabidopsis circadian clock incorporates a cADPR-based feedback loop. Science 318, 1789-1792 (2007). [Abstract] [Full Text]

T. Imaizumi, S. A. Kay, J. I. Schroeder, Daily watch on metabolism. Science 318, 1730-1731 (2007). [Summary] [Full Text]

Citation: L. B. Ray, P. J. Hines, Circadian Rhythm Methods. Sci. STKE 2007, tw460 (2007).

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