miRNAs and regulation of cell signaling.

MicroRNAs (miRNAs) regulate gene expression post-transcriptionally by binding to target mRNAs in a sequence-specific manner. A large number of genes appear to be the target of miRNAs, and an essential role for miRNAs in the regulation of various conserved cell signaling cascades, such as mitogen-activated protein kinase, Notch and Hedgehog, is emerging. Extensive studies have also revealed the spatial and temporal regulation of miRNA expression by various cell signaling cascades. The insights gained in such studies support the idea that miRNAs are involved in the highly complex network of cell signaling pathways. In this minireview, we present an overview of these complex networks by providing examples of recent findings.