title: The adaptive response of MyoD family proteins in overloaded, regenerating and denervated rat muscles.
abstract: Using Western blot analysis, we investigated whether the amount of myogenic regulatory factors differs in slow-type and fast-type muscles. In addition, we examined the adaptive response of myogenic regulatory factor protein in the overloaded rat muscles by the ablation of synergists, in the regenerating muscles following bupivacaine injection and in the denervated muscle. The amount of myogenin protein in the slow-type muscle was markedly greater. In contrast, the proteins MyoD and Myf-5 were selectively accumulated in the fast-type muscles. A gradual down-regulation of MyoD and Myf-5 proteins was detected in the denervated fast-type muscles, but not in the myogenin protein content. A rapid down-regulation of myogenic regulatory factor protein was observed both of the mechanically overloaded and in the regenerating muscles. These results indicate that the fast-type-specific gene expression in muscle is modulated by MyoD and Myf-5 proteins and suggest that myogenin protein plays an important role in the reconstruction of damaged neuromuscular connections.
authors.affiliation: Department of Physiology, Institute for Developmental Research, Aichi Human Service Center, Kamiya-cho, Kasugai, Aichi 480-0392, Japan. sakuma@inst-hsc.pref.aichi.jp
authors.forename: K
authors.initials: K
authors.lastname: Sakuma
authors.forename: K
authors.initials: K
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Sano
authors.forename: I
authors.initials: I
authors.lastname: Uramoto
authors.forename: K
authors.initials: K
authors.lastname: Sakamoto
authors.forename: T
authors.initials: T
authors.lastname: Totsuka
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D004268:DNA-Binding Proteins; D003714:Denervation; D015536:Down-Regulation; D005260:Female; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D009124:Muscle Proteins / Q000032:analysis; D018482:Muscle, Skeletal / Q000294:innervation / Q000378:metabolism / Q000502:physiology*; D017570:MyoD Protein / Q000032:analysis / Q000378:metabolism*; D051787:Myogenic Regulatory Factor 5; D018008:Myogenin / Q000032:analysis; D010424:Pentobarbital / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration; D013997:Time Factors; D014020:Tissue Extracts / Q000032:analysis; D015534:Trans-Activators
chemical_list: D004268:DNA-Binding Proteins; D009124:Muscle Proteins; D017570:MyoD Protein; C503803:Myog protein, rat; D051787:Myogenic Regulatory Factor 5; D018008:Myogenin; D014020:Tissue Extracts; D015534:Trans-Activators; D010424:Pentobarbital