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Science 338 (6105): 338-340

Copyright © 2012 by the American Association for the Advancement of Science

Circadian Surprise—It's Not All About Transcription

Colleen J. Doherty1, and Steve A. Kay2

The integral role of the circadian clock in numerous aspects of health has prompted extensive study of the molecular architecture of clock networks. Understanding how the clock controls downstream processes has widespread clinical impacts, as it affects many diseases and biological processes including immune responses, metabolism, and aging (13). The primary molecular components of the mammalian oscillator and a detailed understanding of the regulatory interactions among them have been well characterized (4, 5). However, one critical question remains unanswered: How do the cogs of this clock translate the rhythmic regulatory relationship among themselves into the plethora of outputs that are under circadian control? On pages 349 and 379 of this issue, Koike et al. (6) and Morf et al. (7) investigate this problem from opposite ends of the spectrum—a genome-wide discovery approach and the functional characterization of a specific factor, respectively—yet they converge to emphasize the importance of posttranscriptional regulation of messenger RNA (mRNA) levels on the clock.

1 Center for Chronobiology, University of California, San Diego, La Jolla, CA 92093–0116, USA.
2 Dana and David Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, CA 90089, USA.

E-mail: cdoherty{at}; stevekay{at}

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