A study has been made on the expression of cellular oncogenes <I>c-myc </I>and <I>c-fos</I> in rate skeletal muscle both <I>in vitro</I> in cell lines and primary culture and <I>in vivo </I>during development and after the induction of two models of hypertrophy. Using the technique of Northern hybridisation, results showed that the pattern of expression of <I>c-myc </I>and <I>c-fos </I>mRNA in primary myoblast cells and in established myoblast and fibroblast cells in culture were similar; stimulation of quiescent cells to proliferate induced expression from the <I>c-fos </I>gene within 30 minutes and the <I>c-myc </I>gene by 2 hours. The findings demonstrate that <I>c-myc</I> and <I>c-fos </I>mRNA levels are increased in terminally differentiated rat skeletal muscle both <I>in vitro </I>and <I>in vivo</I>. They confirm work which showed that <I>c-myc </I>is not exclusively connected with cell proliferation (Endo and Nadal-Ginard 1986) and extend previous work into the increased expression of <I>c-myc </I>and <I>c-fos </I>mRNA in cardiac muscle induced to hypertrophy (Mulvagh <I>et al., </I>1987; Izumo <I>et al</I>., 1988; Komuro <I>et al., </I>1988). The possible location of the elevated expression within the muscle after hypertrophy and the relative contributions from an inflammatory response, satellite cells and myofibres are discussed. Elevation of <I>c-myc </I>and <I>c-fos</I> mRNA in hypertrophy induced both surgically by tenotomy and pharmocologically with clenbuterol argue against a significant contribution from infiltrating fibroblasts, while from the literature, the activation of satellite cells appears to occur later. It is concluded that the elevated expression of <I>c-myc </I>in skeletal muscle is probably located within the myofibres and may be linked to mechanisms of cell enlargement. However further confirmation with <I>in situ </I>hybridisation and immunohistochemistry is required.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:295585 |
| Date | January 1991 |
| Creators | Whitelaw, Philippa F. |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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