Regulation of myogenin protein expression in denervated muscles from young and old rats

1  Mental Health Research Institute and 2  Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 Myogenin is a muscle-specific transcription factor participating in denervation-induced increases in nicotinic ACh receptor (nAChR) gene expression. Although myo...

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Bibliographic Details
Published in:American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2000-07, Vol.279 (1), p.179-R188
Main Authors: Kostrominova, Tatiana Y, Macpherson, Peter C. D, Carlson, Bruce M, Goldman, Daniel
Format: Article
Language:English
Subjects:
Aging - physiology
Animals
Blotting, Western
Cell Nucleus - metabolism
Immunohistochemistry
Muscle Denervation
Muscle Fibers, Skeletal - metabolism
Muscle, Skeletal - innervation
Muscle, Skeletal - metabolism
Myogenin - genetics
Myogenin - metabolism
Rats
Rats, Wistar
Receptors, Cholinergic - genetics
Receptors, Cholinergic - metabolism
RNA, Messenger - biosynthesis
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Summary:1  Mental Health Research Institute and 2  Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 Myogenin is a muscle-specific transcription factor participating in denervation-induced increases in nicotinic ACh receptor (nAChR) gene expression. Although myogenin RNA expression in denervated muscle is well documented, surprisingly little is known about myogenin protein expression. Therefore, we assayed myogenin protein and RNA in innervated and denervated muscles from young (4 mo) and old (24-32 mo) rats and compared this expression to that of the nAChR -subunit RNA. These assays revealed increased myogenin protein expression within 1 day of denervation, preceding detectable increases in nAChR RNA. By 3 days of denervation, myogenin and nAChR -subunit RNA were increased 500- and 130-fold, respectively, whereas myogenin protein increased 14-fold. Interestingly, old rats (32 mo) had 6-fold higher myogenin protein and ~80-fold higher mRNA levels than young rats. However, after denervation, expression levels were similar for young and old animals. The increased myogenin expression during aging, which tends to localize to small fibers, likely reflects spontaneous denervation and/or regeneration. Our results show that increased myogenin protein in denervated muscles correlates with the upregulation of its mRNA. nicotinic acetylcholine receptor; aging; gene expression * T. Y. Kostrominova and P. C. D. Macpherson contributed equally to this work.
ISSN:0363-6119
1522-1490
DOI:10.1152/ajpregu.2000.279.1.r179