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XB-ART-20650
Dev Biol November 1, 1994; 166 (1): 18-33.

Overexpression of XMyoD or XMyf5 in Xenopus embryos induces the formation of enlarged myotomes through recruitment of cells of nonsomitic lineage.

Ludolph DC , Neff AW , Mescher AL , Malacinski GM , Parker MA , Smith RC .


Abstract
The myogenic regulatory factors (MRFs) MyoD and Myf5 are the earliest described muscle-specific genes to be expressed in Xenopus development. To study the in vivo effects of overexpressing Xenopus MyoD and Myf5, synthetic RNAs were microinjected into single blastomeres of 2- to 32-cell stage Xenopus embryos. In vivo overexpression of these MRFs initiates the precocious and ectopic expression of actin and myosin. The effects of unilateral injection of either mRNA were indistinguishable; embryos injected at the 2-cell stage showed ipsilaterally enlarged cranial and anterior trunk myotomes composed of increased numbers of primary myotome myocytes. In addition, formation of ectopic muscle in lateral plate and neural tissue was observed. The MRF-induced effects persist through secondary myogenesis, with the enlarged cranial myotomes failing to undergo the normal program of degeneration. Experiments combining MRF RNA and lineage tracer injections showed that myotomal enlargement is due in part to the contribution of cells of nonsomitic lineage to the myotome, rather than to an increase in muscle precursor cell division. Overexpression of XMyoD and XMyf5 also affected the morphogenesis of the skin and the nervous system. These results reveal that overexpression of XMyoD or XMyf5 in vivo clearly influences the regulation of early myogenesis and the morphogenesis of skin and nervous tissue.

PubMed ID: 7525388
Article link: Dev Biol
Grant support: [+]
Genes referenced: actl6a elavl1 gal.2 ide lsamp myf5 myh3 myod1 myrf
Antibodies: Act3 Ab1 Lsamp Ab1 Somite Ab1


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