REPRODUCTIONREVIEW Many routes to the same destination: lessons from skeletal muscle development Gi Fay Mok and Dylan Sweetman Division of Animal Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK Correspondence should be addressed to D Sweetman; Email:
[email protected] Abstract The development and differentiation of vertebrate skeletal muscle provide an important paradigm to understand the inductive signals and molecular events controlling differentiation of specific cell types. Recent findings show that a core transcriptional network, initiated by the myogenic regulatory factors (MRFs; MYF5, MYOD, myogenin and MRF4), is activated by separate populations of cells in embryos in response to various signalling pathways. This review will highlight how cells from multiple distinct starting points can converge on a common set of regulators to generate skeletal muscle. Reproduction (2011) 141 301–312 Introduction in origin. The locations of these areas in the embryo are shown schematically in Fig. 1A. Most muscles are derived Understanding the process of differentiation is a central from paraxial trunk mesoderm (i.e. the mesoderm lying concern of developmental biology, and the study of immediately adjacent to the midline, see Fig. 1A and B), vertebrate skeletal muscle provides an excellent para- which forms somites, and head mesoderm. Additionally, digm to understand this problem. Investigations over some lateral neck mesoderm has also been shown to have many years have shed light on the inductive processes myogenic potential. Trunk, head, neck and limb muscles within embryos that lead to myogenesis and the are all produced by distinct developmental pathways, molecular events that underpin this.