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Autophagy defect causes loss of muscle in aging

June 8, 2015
Toyohashi University of Technology
Researchers have detected marked upregulation of p62/SQSTM1, but not LC3, protein levels in the cytosol of sarcopenic muscle fibers in mice. This unbalanced expression appears to induce an autophagic defect in skeletal muscle and consequent loss of muscle mass. This finding contributes to our understanding of the molecular mechanism of sarcopenia, or muscle aging.

Sarcopenia is the aging-related loss of skeletal muscle mass and strength. Preventing sarcopenia is important for maintaining a high quality of life (QOL) in the aged population. However, the molecular mechanism of sarcopenia has not yet been unraveled and is still a matter of debate.

Determining whether the levels of autophagy-related mediators (e.g., p62/SQSTM1, LC3, etc.) in muscle change with aging is important to understanding sarcopenia. Such information could enhance the therapeutic strategies for attenuating mammalian sarcopenia.

In previous studies, autophagic defects were detected in the sarcopenic muscle of mice, rats, and humans. However, all these studies involved only western blotting analyses of crude not cell-fractionated muscle homogenates. Thus, these data were insufficient to describe the adaptive changes in autophagy-linked molecules within sarcopenic muscle.

Associate Professor Kunihiro Sakuma and his colleagues at Toyohashi Tech found a marked accumulation of p62/SQSTM1 in the sarcopenic quadriceps muscle of mice using two different methods (western blotting of cell-fractionated homogenates and immunofluorescence). In contrast, the expression level of LC3, a partner of p62/SQSTM1 in autophagy progression, was not modulated.

The found autophagic defect improves our understanding of the mechanism underlying sarcopenia. The researchers would like to further study this mechanism with an aim to attenuate sarcopenia by improving this autophagic defect using nutrient- and pharmaceutical-based treatments.

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Materials provided by Toyohashi University of Technology. Note: Content may be edited for style and length.

Journal Reference:

  1. Kunihiro Sakuma, Wataru Aoi, Akihiko Yamaguchi. Current understanding of sarcopenia: possible candidates modulating muscle mass. Pflügers Archiv - European Journal of Physiology, 2014; 467 (2): 213 DOI: 10.1007/s00424-014-1527-x

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Toyohashi University of Technology. "Autophagy defect causes loss of muscle in aging." ScienceDaily. ScienceDaily, 8 June 2015. <>.
Toyohashi University of Technology. (2015, June 8). Autophagy defect causes loss of muscle in aging. ScienceDaily. Retrieved June 18, 2024 from
Toyohashi University of Technology. "Autophagy defect causes loss of muscle in aging." ScienceDaily. (accessed June 18, 2024).

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