Curcumin induces stabilization of Nrf2 protein through Keap1 cysteine modification

  • Biochem Pharmacol. 2020 Mar;173:113820. doi: 10.1016/j.bcp.2020.113820.
Jun Wan Shin  1 ,  Kyung-Soo Chun  2 ,  Do-Hee Kim  3 ,  Su-Jung Kim  1 ,  Seong Hoon Kim  1 ,  Nam-Chul Cho  4 ,  Hye-Kyung Na  5 ,  Young-Joon Surh  6
Affiliations
  • 1. Tumor Microenvironment Research Center, College of Pharmacy, Seoul National University, Seoul, South Korea.
  • 2. Department of Pharmacy, College of Pharmacy, Keimyung University, Daegu, South Korea.
  • 3. Tumor Microenvironment Research Center, College of Pharmacy, Seoul National University, Seoul, South Korea; Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, South Korea.
  • 4. C&C Research Laboratories, DRC, Sungyunkwan University, Suwon, South Korea.
  • 5. Department of Food Science and Biotechnology, College of Knowledge-based Services Engineering, Sungshin Women's University, Seoul, South Korea.
  • 6. Tumor Microenvironment Research Center, College of Pharmacy, Seoul National University, Seoul, South Korea; Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, South Korea; Cancer Research Institute, Seoul National University, Seoul, South Korea. Electronic address: [email protected].
PMID: 31972171 DOI: 10.1016/j.bcp.2020.113820
Abstract

The present study was aimed to investigate the effects of curcumin, a representative chemopreventive phytochemical with pronounced antioxidant and anti-inflammatory properties, on activation of Nrf2 and expression of its target protein heme oxygenase-1 (HO-1) in mouse skin in vivo and in cultured murine epidermal cells. Treatment of mouse epidermal JB6 cells with curcumin resulted in the induction of HO-1 expression, and this was abrogated in cells transiently transfected with Nrf2 siRNA. While curcumin treatment increased protein expression of Nrf2, it did not alter the steady-state level of the Nrf2 mRNA transcript. Treatment of cells with curcumin stabilized Nrf2 by inhibiting ubiquitination and subsequent 26S proteasomal degradation of this transcription factor. Tetrahydrocurcumin, a non-electrophilic analogue of curcumin that lacks the α,β-unsaturated carbonyl group, failed to induce HO-1 expression as well as nuclear translocation of Nrf2 and its binding to the antioxidant/electrophile response elements. Cells transfected with a mutant Keap1 protein in which cysteine 151 (Cys151) is replaced by serine exhibited marked reduction in curcumin-induced Nrf2 transactivation. Mass spectrometric analysis revealed that curcumin binds to Keap1 Cys151, supporting that this amino acid is a critical target for curcumin modification of Keap1, which facilitates the liberation of Nrf2. Thus, it is likely that the α,β-unsaturated carbonyl moiety of curcumin is essential for its binding to Keap1 and stabilization of Nrf2 by hampering ubiquitination and proteasomal degradation.

Keywords
Chemoprevention; Curcumin; Heme oxygenase; Keap1; Nrf2.
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