MyoD gene

Connolly, B., Trenholme, K. and Smith, D.F. (1996) Molecular cloning of a myoD-like gene from the parasitic nematode, Trichinella spiralis. Molecular and Biochemical Parasitology 81, 137—149. 

In Xenopus, in addition to the role in 5S RNA gene regulation, somatic HI has been shown to be involved in further stages of differentiation. The restriction of myoD expression, a marker for the loss of the ability by ectodermal cells to differentiate into mesoderm, requires the presence of somatic histone HI [144]. Again, the globular domain alone and not the whole HI molecule is required to confer this effect [142]. 

Muscle, whose structure and function are discussed in Chapter 19, develops in response to four members of the myoD family. These include myoD, myogenin, myf5, and MRF4.417-419 All are muscle-specific transcription factors of the basic helix -loop -helix class. An unusual aspect of muscle development is formation of multinucleate myotubes (muscle fibers p. 1096)420 Apoptosis plays an important role in muscle development and can present significant complications in damaged cardiac muscle.421 Defects in several developmental control genes are responsible for congenital heart diseases.422... 

Most cancer cells show abnormal differentiation patterns as compared to their normal counterparts. For years, the molecular mechanisms of differentiation have been intensively investigated, but poorly understood. Differentiation begins shortly after the first few cell divisions that follow fertilization. Throughout development, and in adult organisms, the ability of a cell to proliferate is intimately connected to its state of differentiation. Adult tissues generally express a variety of factors fliat act to maintain both the proliferation and differentiation status of cells. These include secreted molecules, transmembrane receptors, intracellular signaling molecules and transcription factors. For example, myoD (81) and c/EBP-a (82) are nuclear factors that activate the transcription of muscle- and adipocyte-specific genes, respectively in addition, both proteins are potent inhibitors of cell proliferation. 

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