Integrating transcriptional and signalling networks during muscle development.

A fundamental aspect of developmental decisions is the ability of groups of cells to obtain the competence to respond to different signalling inputs. This information is often integrated with intrinsic transcriptional networks to produce diverse developmental outcomes. Studies in Drosophila are starting to reveal a detailed picture of the regulatory circuits controlling the subdivision of the dorsal mesoderm, which gives rise to diverse muscle types including cardioblasts, pericardial cells, body wall muscle and gut muscle. The combination of a common set of mesoderm autonomous transcription factors (e.g. Tinman and Twist) and spatially restricted inductive signals (e.g. Dpp and Wg) subdivide the dorsal mesoderm into different competence domains. The integration of additional signalling inputs with localised repression within these competence domains results in diverse transcriptional responses within neighbouring cells, which in turn generates muscle diversity. Copyright 2004 Elsevier Ltd.