title: Glucocorticoid inhibition of C2C12 proliferation rate and differentiation capacity in relation to mRNA levels of the MRF gene family.
abstract: The muscle regulatory factors (MRF) gene family regulate muscle fibre development. Several hormones and drugs also affect muscle development. Glucocorticoids are the only drugs reported to have a beneficial effect on muscle degenerative disorders. We investigated the glucocorticoid-related effects on C2C12 myoblast proliferation rate, morphological differentiation, and subsequent mRNA expression patterns of the MRF genes. C2C12 cells were incubated with the glucocorticoids dexamethasone or alpha-methyl-prednisolone. Both glucocorticoids showed comparable effects. Glucocorticoid treatment of C2C12 cells during the proliferative phase reduced the proliferation rate of the cells dose dependently, especially during the third and fourth day of culture, increased MyoD1, myf-5, and MRF4 mRNA levels, and reduced myogenin mRNA level, compared to untreated control cells. Thus, the mRNA level of proliferation-specific MyoD1 and myf-5 expression does not seem to associate with C2C12 myoblast proliferation rate. Glucocorticoid treatment of C2C12 cells during differentiation reduced the differentiation capacity dose dependently, which is accompanied by a dose dependent reduction of myogenin mRNA level, and increased MyoD1, myf-5, and MRF4 mRNA levels compared to untreated control cells. Therefore, we conclude that glucocorticoid treatment reduces differentiation of C2C12 myoblasts probably through reduction of differentiation-specific myogenin mRNA level, while inducing higher mRNA levels of proliferation-associated MRF genes.
authors.affiliation: Institute for Animial Science and Health, Department of Animal Breeding and Genetics, Lelystad, The Netherlands. m.f.w.tepas@id.wag-ur.nl
authors.forename: M F
authors.initials: MF
authors.lastname: te Pas
authors.forename: P R
authors.initials: PR
authors.lastname: de Jong
authors.forename: F J
authors.initials: FJ
authors.lastname: Verburg
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D004268:DNA-Binding Proteins; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D008775:Methylprednisolone / Q000494:pharmacology; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D009124:Muscle Proteins / Q000187:drug effects / Q000235:genetics; D017570:MyoD Protein / Q000187:drug effects / Q000235:genetics; D051787:Myogenic Regulatory Factor 5; D018006:Myogenic Regulatory Factors / Q000187:drug effects / Q000235:genetics*; D018008:Myogenin / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D015534:Trans-Activators
chemical_list: D004268:DNA-Binding Proteins; D005938:Glucocorticoids; D009124:Muscle Proteins; C497418:Myf5 protein, mouse; D017570:MyoD Protein; C503801:Myog protein, mouse; D051787:Myogenic Regulatory Factor 5; D018006:Myogenic Regulatory Factors; D018008:Myogenin; D012333:RNA, Messenger; D015534:Trans-Activators; C063403:myogenic factor 6; D003907:Dexamethasone; D008775:Methylprednisolone