Modulation of Nrf2/Keap1 system by Wasabi 6-methylthiohexyl isothiocyanate in ARE-mediated NQO1 expression

Authors

  • Yoshimi Korenori,

    1. Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Kagoshima, Japan
    Search for more papers by this author
    • These authors contributed equally to this work.

  • Shunsuke Tanigawa,

    1. Course of Biochemical Science and Technology, United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan
    Search for more papers by this author
    • These authors contributed equally to this work.

  • Takuma Kumamoto,

    1. Course of Biochemical Science and Technology, United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan
    Search for more papers by this author
  • Si Qin,

    1. Course of Biochemical Science and Technology, United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan
    Search for more papers by this author
  • Yosuke Daikoku,

    1. Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Kagoshima, Japan
    Search for more papers by this author
  • Koji Miyamori,

    1. Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Kagoshima, Japan
    Search for more papers by this author
  • Masashi Nagai,

    1. Kinjirushi Co., Ltd., Nagoya City, Aichi, Japan
    Search for more papers by this author
  • De-Xing Hou

    Corresponding author
    1. Course of Biochemical Science and Technology, United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan
    • Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Kagoshima, Japan
    Search for more papers by this author

Correspondence: Professor De-Xing Hou, Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Korimoto 1–21-24, Kagoshima 890–0065, Japan

E-mail: hou@chem.agri.kagoshima-u.ac.jp

Fax: +81-99-285-8649

Abstract

Scope

6-Methylthiohexyl isothiocyanate (6-MTITC), one of the major bioactive ingredients in Japanese Wasabi, has revealed cytoprotective and cancer chemopreventive effects. This study aims to clarify the molecular mechanisms how 6-MTITC modulates nuclear factor E2-related factor 2 (Nrf2)/Kelchlike ECH-associating protein 1 (Keap1) system in antioxidant-responsive element (ARE)-mediated nicotinamide adenine dinucleotide phosphate (NADP): quinone oxidoreductase 1 (NQO1) expression.

Methods and results

HepG2 cells were treated with 6-MTITC with varying time and dose. NQO1, Nrf2, and Keap1 proteins were detected by Western blotting. ARE transactivation was detected by electrophilic mobility shift assay and reporter gene assay. Nuclear localization of Nrf2 was determined by immunocytochemistry assay. Ubiquitination of Nrf2 and Keap1 was detected using immunoprecipitation after treatment with MG132. Small interfering RNA was used to knockdown Nrf2 or Keap1. The results revealed that 6-MTITC modulated Nrf2/ARE pathway by stimulating Keap1 modification, and inhibiting Nrf2 ubiquitination and protein turnover. These actions finally increased nuclear Nrf2 accumulation and ARE-binding activity. Moreover, silencing Nrf2 markedly reduced ARE-driven activity induced by 6-MTITC.

Conclusion

6-MTITC modulated ARE-driven NQO1 expression by stabilizing Nrf2 with enhanced Keap1 modification and decreased Nrf2 degradation.

Ancillary