Decreased muscle atrophy F-box (MAFbx) expression in regenerating muscle after muscle-damaging exercise

Atsushi Okada, Yusuke Ono, Ryoichi Nagatomi, Koshi N. Kishimoto, Eiji Itoi

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


A muscle-specific ubiquitin ligase, Muscle Atrophy F-box (MAFbx), is known to mediate the degradation of muscle-specific transcription factor MyoD in vitro. Its regulation in regenerating skeletal muscle, however, has not been clarified. We looked for evidence of MAFbx down-regulation in the course of regeneration after muscle damaging exercise. The soleus and gastrocnemius muscles of mice were subjected to forced eccentric contraction by electrical stimulation to induce muscle damage. The expression of developmental myosin heavy chain (MHCd) suggested that muscle regeneration took place from Day 3 after exercise. mRNA and protein expression of MAFbx decreased on Days 3, 5, and 7, while MyoD protein increased on Days 3, 5, and 7. Although further study is required to establish the causal relationships, downregulation of MAFbx may have reduced MyoD degradation in favor of muscle regeneration.

Original languageEnglish
Pages (from-to)1246-1253
Number of pages8
JournalMuscle and Nerve
Issue number4
Publication statusPublished - 2008 Oct


  • Eccentric exercise
  • MAFbx
  • MyoD
  • Regeneration
  • Skeletal muscle


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