Molecular mechanisms regulating myogenic determination and differentiation

The myogenic regulatory factors are necessary for the determination and ter minal differentiation of skeletal muscle. Gene targeting experiments have d emonstrated that MyoD and Myf5 are important for myogenic determination whe reas myogenin and MRF4 are important for terminal differentiation and linea ge maintenance. During development, all trunk skeletal muscle is derived fr om the somite. Two spatially distinct sources of myogenic progenitors are d efined by the expression of MyoD or Myf5 and these give rise to hypaxial an d epaxial musculature. Both in vivo and in vitro analyses have provided a d etailed picture regarding the molecular events controlling lineage determin ation, cell migration, terminal differentiation and tissue repair. Signal t ransduction pathways regulating cell cycle, protein-protein interactions an d myogenic factor gene activation are implicated in the regulation of myoge nesis. Recent experiments examining the origin and stem-cell capacity of sa tellite cells suggest that these cells may originate from the vascular syst em, are multipotential and may be useful for the treatment of several degen erative diseases.