Widespread uncoupling between transcriptome and translatome variations after a stimulus in mammalian cells

Background:
The classical view on eukaryotic gene expression proposes the scheme of a forward flow forwhich fluctuations in mRNA levels upon a stimulus contribute to determine variations inmRNA availability for translation. Here we address this issue by simultaneously profilingwith microarrays the total mRNAs (the transcriptome) and the polysome-associated mRNAs (the translatome) after EGF treatment of human cells, and extending the analysis to other 19different transcriptome/translatome comparisons in mammalian cells following differentstimuli or undergoing cell programs.
Results:
Triggering of the EGF pathway results in an early induction of transcriptome and translatomechanges, but 90% of the significant variation is limited to the translatome and the degree ofconcordant changes is less than 5%. The survey of other 19 differenttranscriptome/translatome comparisons shows that extensive uncoupling is a general rule, interms of both RNA movements and inferred cell activities, with a strong tendency oftranslation-related genes to be controlled purely at the translational level. By differentstatistical approaches, we finally provide evidence of the lack of dependence betweenchanges at the transcriptome and translatome levels.
Conclusions:
We propose a model of diffused independency between variation in transcript abundancesand variation in their engagement on polysomes, which implies the existence of specificmechanisms to couple these two ways of regulating gene expression.

Source: http://www.biomedcentral.com/1471-2164/13/220

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