Spatiotemporal aspects of MicroRNA-mediated gene regulation

MicroRNA-mediated modulation of translation has been recently discovered as a new dimension in gene expression regulation. In this chapter we review how this regulation operates in time between the fast protein modification and degradation steps on the one hand and the slow transcriptional reprogramming associated with more stable changes in gene expression patterns on the other hand. We also discuss the additional layer of complexity associated with spatial redistribution of the RNA silencing machinery in subcellular structures. Various stress conditions induce both a transient change in microRNA expression within the first few hours after exposure and a redistribution of the RNA silencing machinery from P-bodies to Stress Granules, which differ in their function and protein content. Insight into the spatiotemporal aspects of the microRNA response will be indispensable for a full understanding of this level of gene regulation.