[Regulation of myogenesis]

Abstract

Molecular-biological and molecular-genetic mechanisms underlying regulation of muscle formation were analyzed from the earliest stages of commitment and determination of myogenic precursors to the terminal stages of muscle differentiation. It was shown how inductive influences of the neural tube and notochord on the somites leading to formation of myotomes are related to expression of genes of the Shh and Wnt families. Differentiation of proliferating myoblasts and myotubes is related to expression of the genes encoding synthesis of bHLH proteins: MyoD and Myf5 in the myoblasts and myogenin and MRF4 in the myotubes. The products of these genes are transcription factors and control the subsequent stages of myogenesis, specifically, myogenin controls expression of the genes of contractile proteins. Changes in the spectra of contractile proteins during ontogenesis and diversity of their isoforms are related both to the expression of various genes and to their alternative splicing. The mechanisms underlying the assembly of myofibrils in ontogenesis, which involve, in addition to myosin and actin, proteins of Z-bands and A-discs, were analyzed.