Posttranscriptional mechanisms in controlling eukaryotic circadian rhythms

Abstract

a b s t r a c tThe circadian clock is essential in almost all living organisms to synchronise biochemical, metabolic, physiological and behavioural cycles to daily changing environmental factors. In a highly conserved fashion, the circadian clock is primarily controlled by multiple positive and negative molecular circuitries that control gene expression. More recently, research in Neurospora and other eukaryotes has uncovered the involvement of additional regulatory components that operate at the posttranslational level to fine tune the circadian system. Though it remains poorly understood, a growing body of evidence has shown that posttranscriptional regulation controls the expression of both circadian oscillator and output gene transcripts at a number of different steps. This regulation is crucial for driving and maintaining robust circadian rhythms. Here we review recent advances in circadian rhythm research at the RNA level.

Nascent-Seq reveals novel features of mouse circadian transcriptional regulation

“…This surprising conclusion was similar when the analysis was restricted to genes with the strongest mRNA rhythms (121/435) and indicates that most cycling mRNAs (862/1204) likely undergo post-transcriptional regulation. This might include the circadian regulation of nuclear RNA processing, export, translational regulation and/or mRNA turnover, as described for the few circadian genes shown to be regulated post-transcriptionally (Kojima et al, 2011; Staiger and Koster, 2011; Zhang et al, 2011). Gene ontology analysis of this arrhythmic transcription-rhythmic mRNA (AR-R) gene set did not reveal any striking enrichment of particular gene functions (Figure 5D).…”

“…It is generally assumed that these rhythms in mRNA expression directly result from temporal changes in transcription. There are, however, a few reports indicating that post-transcriptional regulation contributes to rhythmic mRNA expression of several genes, including core clock genes (reviewed in Kojima et al, 2011; Staiger and Green, 2011; Staiger and Koster, 2011; Zhang et al, 2011), but this has never been studied in detail at the genome-wide level. Circadian post-transcriptional regulation may impact rhythmic mRNA expression at many different levels, such as mRNA splicing, stability and translation.…”

Mutation of Arabidopsis SPLICEOSOMAL TIMEKEEPER LOCUS1 Causes Circadian Clock Defects

“…Such coordination is achieved through the action of the circadian system, a timing mechanism consisting of interlocked feedback loops that generate a sustainable oscillation of ;24 h (Harmer, 2009). While much of the initial characterization of the circadian system focused upon transcriptional regulation, it is now apparent that considerable regulation occurs posttranscriptionally (Cibois et al, 2010;Kojima et al, 2011;Zhang et al, 2011). Transcript processing (in particular, alternative splicing [AS]), protein stability, and cofactor availability have all been reported to influence circadian rhythms in a variety of species (Nakahata et al, 2008;Filichkin et al, 2010;van Ooijen et al, 2011;James et al, 2012).…”

Gene Regulation of Carbon Fixation, Storage, and Utilization in the DiatomPhaeodactylum tricornutumAcclimated to Light/Dark Cycles

“…The internal molecular clocks are related to gene transcription and translation regulated in feedback loops (TessmarRaible et al, 2011), and the circadian control of many cell processes has been studied in the green alga Chlamydomonas reinhardtii (Schulze et al, 2010). Control points can be at the translational level (Mittag, 2003) or the posttranslational level (Zhang et al, 2011) and sometimes are regulated as a feedback signal system. As an example, oscillations of sugar content contributed to sugar-responsive transcripts in plant cells (Haydon et al, 2011).…”