Spotlight on post-transcriptional control in the circadian system

An endogenous timing mechanism, the circadian clock, causes rhythmic expression of a considerable fraction of the genome of most organisms to optimally align physiology and behavior with their environment. Circadian clocks are self-sustained oscillators primarily based on transcriptional feedback loops and post-translational modification of clock proteins. It is increasingly becoming clear that regulation at the RNA level strongly impacts the cellular circadian transcriptome and proteome as well as the oscillator mechanism itself. This review focuses on posttranscriptional events, discussing RNA-binding proteins that, by influencing the timing of pre-mRNA splicing, polyadenylation and RNA decay, shape rhythmic expression profiles. Furthermore, recent findings on the contribution of microRNAs to orchestrating circadian rhythms are summarized.