論文

査読有り 国際誌
2021年9月

The ubiquitin ligase Ozz decreases the replacement rate of embryonic myosin in myofibrils

Physiological Reports
  • Emi Ichimura
  • ,
  • Koichi Ojima
  • ,
  • Susumu Muroya
  • ,
  • Takahiro Suzuki
  • ,
  • Ken Kobayashi
  • ,
  • Takanori Nishimura

9
17
開始ページ
e15003
終了ページ
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.14814/phy2.15003
出版者・発行元
Wiley

Myosin, the most abundant myofibrillar protein in skeletal muscle, functions as a motor protein in muscle contraction. Myosin polymerizes into the thick filaments in the sarcomere where approximately 50% of embryonic myosin (Myh3) are replaced within 3 h (Ojima K, Ichimura E, Yasukawa Y, Wakamatsu J, Nishimura T, Am J Physiol Cell Physiol 309: C669-C679, 2015). The sarcomere structure including the thick filament is maintained by a balance between protein biosynthesis and degradation. However, the involvement of a protein degradation system in the myosin replacement process remains unclear. Here, we show that the muscle-specific ubiquitin ligase Ozz regulates replacement rate of Myh3. To examine the direct effect of Ozz on myosin replacement, eGFP-Myh3 replacement rate was measured in myotubes overexpressing Ozz by fluorescence recovery after photobleaching. Ozz overexpression significantly decreased the replacement rate of eGFP-Myh3 in the myofibrils, whereas it had no effect on other myosin isoforms. It is likely that ectopic Ozz promoted myosin degradation through increment of ubiquitinated myosin, and decreased myosin supply for replacement, thereby reducing myosin replacement rate. Intriguingly, treatment with a proteasome inhibitor MG132 also decreased myosin replacement rate, although MG132 enhanced the accumulation of ubiquitinated myosin in the cytosol where replaceable myosin is pooled, suggesting that ubiquitinated myosin is not replaced by myosin in the myofibril. Collectively, our findings showed that Myh3 replacement rate was reduced in the presence of overexpressed Ozz probably through enhanced ubiquitination and degradation of Myh3 by Ozz.

リンク情報
DOI
https://doi.org/10.14814/phy2.15003
PubMed
https://www.ncbi.nlm.nih.gov/pubmed/34435451
PubMed Central
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8387782
URL
https://onlinelibrary.wiley.com/doi/pdf/10.14814/phy2.15003
URL
https://onlinelibrary.wiley.com/doi/full-xml/10.14814/phy2.15003
ID情報
  • DOI : 10.14814/phy2.15003
  • ISSN : 2051-817X
  • eISSN : 2051-817X
  • PubMed ID : 34435451
  • PubMed Central 記事ID : PMC8387782

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