Research Article: The Circadian Clock Coordinates Ribosome Biogenesis

Date Published: January 3, 2013

Publisher: Public Library of Science

Author(s): Céline Jouffe, Gaspard Cretenet, Laura Symul, Eva Martin, Florian Atger, Felix Naef, Frédéric Gachon, Paul E. Hardin

Abstract: The authors identify a new role of the circadian clock in coordinating mRNA translation during ribosome biogenesis, a key process for cell metabolism.

Partial Text: Circadian rhythms in behavior and physiology reflect the adaptation of organisms exposed to daily light-dark cycles. As a consequence, most aspects of metabolism and behaviour are under the control of these rhythms [1]. At a molecular level, in all the studied species, the rhythmic expression of the genes involved originates in the network of interconnected transcriptional and translational feedback loops [2]. In mammals, the heterodimer composed of BMAL1 and its partners CLOCK or NPAS2 is a transcriptional activator that regulates transcription of the Period (Per) and Cryptochrome (Cry) genes that code for repressors of BMAL1 heterodimer activity, thus closing a negative feedback loop that generates rhythms of approximately 24 h [1],[2]. Many efforts during the last decade have characterized rhythmically expressed genes and delimit the impact of the circadian clock on physiology. Numerous circadian transcriptome studies in different species and organs show that approximately 10% of the genes are rhythmically expressed. The functions of these genes established the role of the circadian clock in temporally gating rhythmic physiology [1],[3]. However, increasing evidence suggests that transcriptional mechanisms are not sufficient to explain numerous observations. For example, it has been shown that many oscillating proteins in mouse liver are encoded by constantly expressed mRNAs [4].