The epigenetic network regulating muscle development and regeneration.

This review focuses on our current knowledge of the epigenetic changes regulating gene expression at the chromatin and DNA level, independently on the primary DNA sequence, to reprogram the nuclei of muscle precursors during developmental myogenesis and muscle regeneration. These epigenetic marks provide the blueprint by which the extra-cellular cues are interpreted at the nuclear level by the transcription machinery to select the repertoire of tissue-specific genes to be expressed. The reversibility of some of these changes necessarily reflects the dynamic nature of skeletal myogenesis, which entails the progression through two antagonistic processes--proliferation and differentiation. Other epigenetic modifications are instead associated to events conventionally considered as irreversible--e.g. maintenance of lineage commitment and terminal differentiation. However, recent results support the possibility that these events can be reversed, at least upon certain experimental conditions, thereby revealing a dynamic nature of many of the epigenetic modifications underlying skeletal myogenesis. The elucidation of the epigenetic network that regulates transcription during developmental myogenesis and muscle regeneration might provide the information instrumental to devise pharmacological interventions toward selective manipulation of gene expression to promote regeneration of skeletal muscles and possibly other tissue.