Circadian posttranscriptional regulatory mechanisms in mammals

The circadian clock drives rhythms in the levels of thousands of proteins in the mammalian cell, arising in part from rhythmic transcriptional regulation of the genes that encode them. However, recent evidence has shown that posttranscriptional processes also play a major role in generating the rhythmic protein makeup and ultimately the rhythmic physiology of the cell. Regulation of steps throughout the life of the messenger RNA (mRNA), ranging from initial mRNA processing and export from the nucleus to extensive control of translation and degradation in the cytosol have been shown to be important for producing the final rhythms in protein levels critical for proper circadian rhythmicity. These findings will be reviewed here.