Skeletal muscle development in the mouse embryo

In this review we discuss the recent findings concerning the mechanisms tha t restrict semitic cells to the skeletal muscle fate, the myogenic regulato ry factors controlling skeletal muscle differentiation and specification of myogenic cell lineages, the nature of inductive signals and the role of se creted proteins in embryonic patterning of the myotome. More specifically, we review data which strongly support the hypothesis that Myf-5 plays a uni que role in development of epaxial muscle, that MyoD plays a unique role in development of hypaxial muscles derived from migratory myogenic precursor cells, and that both genes are responsible for development of intercostal a nd abdominal muscles (hypaxial muscles that develop from the dermatomal epi thelia). In addition, while discussing upstream and post-translational regu lation of myogenic regulatory factors (MRFs), we suggest that correct forma tion of: the myotome requires a complex cooperation of DNA, binding protein s and cofactors, as well as inhibitory function of non-muscle cells of the forming somite, whose proteins would sequester and suppress the transcripti on of MRFs. Moreover, in the third part of our review, we discuss embryonic structures, secreted proteins and myogenic induction. However, although di fferent signaling molecules with activity in the process of somite patterni ng have been identified, not many of them are found to be necessary during in vivo embryonic development. To understand their functions, generation of multiple mutants or conditional/tissue-specific mutants will be necessary.