Massive translational repression of gene expression during mouse erythroid differentiation

We took advantage of a mouse erythroid differentiation system to determine the relative contribution of transcriptional and translational control during this process. Comparison of expression data obtained with total cytoplasmic mRNAs or polysome-bound mRNAs (actively translated mRNAs) on Affymetrix high-density oligonucleotide microarrays revealed different characteristics of the two regulatory mechanisms. Indeed, mRNA expression from a vast majority of genes was affected, albeit most changes were relatively small and occurred at a low pace. Translational control, however, affected a smaller fraction of genes but was effective at earlier time-points. This analysis unravels six clusters of genes showing no significant variation in mRNA expression levels whereas they are submitted to translational regulation. Their involvement in terminal mouse erythropoiesis may prove to be highly relevant. Furthermore, the data from specific and functional categories of genes emphasize that translational control, not only reinforces the transcriptional effect, but allows the cell to increase the complexity in gene expression regulation patterns. ►Identification of six clusters of genes strictly translationally regulated ►Control of mRNA expression and translation efficiency display distinct characteristics ►Translational control affects gene expression differentially in terms of kinetics, response intensity and class of genes also affected transcriptional regulation ►Translational control affects a smaller fraction of genes but was effective at earlier time-points as regulation on a transcriptional level ►56% of all the regulated genes by a factor of three are exclusively controlled by mRNA expression, whereas 16% of them are submitted solely to translational regulation and 28% are regulated by both mechanisms