Andrea De Martino — Human Genetics Foundation & CNR-NANOTEC#
RNA ecosystems: does competition for post-transcriptional regulators shape regulation? #
Competition for limited molecular resources (nutrients, ribosomes, RNAp, tRNA, etc.) can influence cellular functions up to the highest levels. Here we review recent modeling work aimed at characterizing how gene expression is affected
by competition for small regulatory RNAs. We shall argue that control through competition may outperform direct transcriptional regulation in reliably generating
expression profiles, and that the effects of competition can build-up to establish system-level regulatory modes carrying out distinct functions, from the buffering of
gene expression noise to the selective activation of specific pathways. 
In this light, the RNA-mediated post-transcriptional regulatory layer 
appears to orchestrate a flexible collective control over gene 
expression, contributing crucially both to the fine tuning of expression levels and to large-scale re-organizations of the transcriptome as required e.g. for differentiation.