Myogenin induces a shift of enzyme activity from glycolytic to oxidative metabolism in muscles of transgenic mice.
J Cell Biol
; 145(3): 633-42, 1999 May 03.
Article
em En
| MEDLINE
| ID: mdl-10225962
ABSTRACT
Physical training regulates muscle metabolic and contractile properties by altering gene expression. Electrical activity evoked in muscle fiber membrane during physical activity is crucial for such regulation, but the subsequent intracellular pathway is virtually unmapped. Here we investigate the ability of myogenin, a muscle-specific transcription factor strongly regulated by electrical activity, to alter muscle phenotype. Myogenin was overexpressed in transgenic mice using regulatory elements that confer strong expression confined to differentiated post-mitotic fast muscle fibers. In fast muscles from such mice, the activity levels of oxidative mitochondrial enzymes were elevated two- to threefold, whereas levels of glycolytic enzymes were reduced to levels 0.3-0.6 times those found in wild-type mice. Histochemical analysis shows widespread increases in mitochondrial components and glycogen accumulation. The changes in enzyme content were accompanied by a reduction in fiber size, such that many fibers acquired a size typical of oxidative fibers. No change in fiber type-specific myosin heavy chain isoform expression was observed. Changes in metabolic properties without changes in myosins are observed after moderate endurance training in mammals, including humans. Our data suggest that myogenin regulated by electrical activity may mediate effects of physical training on metabolic capacity in muscle.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Miogenina
/
Músculo Esquelético
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Respiração Celular
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Glicólise
Limite:
Animals
Idioma:
En
Ano de publicação:
1999
Tipo de documento:
Article