ReviewToo many ways to make a muscle: Evolution of GRNs governing myogenesis

Animal development is an elaborate process encoded in the genome. Regulatory genes encode transcription factors and signaling molecules, and their expression is under the control of cis-regulatory modules that define spatially defined transcriptional regulatory states. The functional linkages among these genes constitute the gene regulatory networks (GRNs) and changes in their architecture due to redeployment of regulatory genes in new locations and/or at different times during embryogenesis results in evolutionary changes. The focus of this review is a wide cross comparison of the GRNs orchestrating myogenesis in several distant phyla in order to provide insights into the evolution of the myogenic regulatory landscape. By comparing the core myogenic network architecture we reveal cases of deep homology, re-deployment of plug-ins, change in hierarchy of action, cooption and novelty.