Nrf2-mediated regulation of skeletal muscle glycogen metabolism

Akira Uruno, Yoko Yagishita, Fumiki Katsuoka, Yasuo Kitajima, Aki Nunomiya, Ryoichi Nagatomi, Jingbo Pi, Shyam Biswal, Masayuki Yamamoto

Research output: Contribution to journalArticle

Abstract

Nrf2 (NF-E2-related factor 2) contributes to the maintenance of glucose homeostasis in vivo. Nrf2 suppresses blood glucose levels by protecting pancreatic β cells from oxidative stress and improving peripheral tissue glucose utilization. To elucidate the molecular mechanisms by which Nrf2 contributes to the maintenance of glucose homeostasis, we generated skeletal muscle (SkM)-specific Keap1 knockout (Keap1MuKO) mice that express abundant Nrf2 in their SkM and then examined Nrf2 target gene expression in that tissue. In Keap1MuKO mice, blood glucose levels were significantly downregulated and the levels of the glycogen branching enzyme (Gbe1) and muscle-type PhKα subunit (Phka1) mRNAs, along with those of the glycogen branching enzyme (GBE) and the phosphorylase b kinase α subunit (PhKα) protein, were significantly upregulated in mouse SkM. Consistent with this result, chemical Nrf2 inducers promoted Gbe1 and Phka1 mRNA expression in both mouse SkM and C2C12 myotubes. Chromatin immunoprecipitation analysis demonstrated that Nrf2 binds the Gbe1 and Phka1 upstream promoter regions. In Keap1MuKO mice, muscle glycogen content was strongly reduced and forced GBE expression in C2C12 myotubes promoted glucose uptake. Therefore, our results demonstrate that Nrf2 induction in SkM increases GBE and PhKα expression and reduces muscle glycogen content, resulting in improved glucose tolerance. Our results also indicate that Nrf2 differentially regulates glycogen metabolism in SkM and the liver.

Original languageEnglish (US)
Pages (from-to)1655-1672
Number of pages18
JournalMolecular and Cellular Biology
Volume36
Issue number11
DOIs
StatePublished - 2016

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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  • Cite this

    Uruno, A., Yagishita, Y., Katsuoka, F., Kitajima, Y., Nunomiya, A., Nagatomi, R., Pi, J., Biswal, S., & Yamamoto, M. (2016). Nrf2-mediated regulation of skeletal muscle glycogen metabolism. Molecular and Cellular Biology, 36(11), 1655-1672. https://doi.org/10.1128/MCB.01095-15