Low proteasomal activity in fast skeletal muscle fibers is not associated with increased age-related oxidative damage

Exp Gerontol. 2019 Mar;117:45-52. doi: 10.1016/j.exger.2018.10.018. Epub 2018 Oct 24.


The skeletal muscle is a crucial tissue for maintaining whole body homeostasis. Aging seems to have a disruptive effect on skeletal muscle homeostasis including proteostasis. However, how aging specifically impacts slow and fast twitch fiber types remains elusive. Muscle proteostasis is largely maintained by the proteasomal system. Here we characterized the proteasomal system in two different fiber types, using a non-sarcopenic aging model. By analyzing the proteasomal activity and amount, as well as the polyubiquitinated proteins and the level of protein oxidation in Musculus soleus (Sol) and Musculus extensor digitorum longus (EDL), we found that the slow twitch Sol muscle shows an overall higher respiratory and proteasomal activity in young and old animals. However, especially during aging the fast twitch EDL muscle reduces protein oxidation by an increase of antioxidant capacity. Thus, under adaptive non-sarcopenic conditions, the two fibers types seem to have different strategies to avoid age-related changes.

Keywords: Aging; Antioxidants; Fast and slow fibers; Mitochondrial respiration; Oxidized proteins; Polyubiquitination; Proteasomal system; Skeletal muscle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aging / metabolism*
  • Aging / physiology
  • Animals
  • Antioxidants / metabolism
  • Cell Respiration / physiology
  • Male
  • Mice, Inbred C57BL
  • Mitochondria, Muscle / physiology
  • Muscle Fibers, Fast-Twitch / metabolism*
  • Muscle Fibers, Slow-Twitch / metabolism
  • Muscle Proteins / metabolism
  • Muscle, Skeletal / metabolism*
  • Oxidative Stress / physiology*
  • Polyubiquitin / metabolism
  • Proteasome Endopeptidase Complex / metabolism*


  • Antioxidants
  • Muscle Proteins
  • Polyubiquitin
  • Proteasome Endopeptidase Complex