Cell Death and Disease (Jul 2021)

A novel Keap1 inhibitor iKeap1 activates Nrf2 signaling and ameliorates hydrogen peroxide-induced oxidative injury and apoptosis in osteoblasts

  • Yue-huan Zheng,
  • Jian-jun Yang,
  • Pei-jun Tang,
  • Yuan Zhu,
  • Zhe Chen,
  • Chang She,
  • Gang Chen,
  • Peng Cao,
  • Xiang-yang Xu

DOI
https://doi.org/10.1038/s41419-021-03962-8
Journal volume & issue
Vol. 12, no. 7
pp. 1 – 10

Abstract

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Abstract An ultra-large structure-based virtual screening has discovered iKeap1 as a direct Keap1 inhibitor that can efficiently activate Nrf2 signaling. We here tested its potential effect against hydrogen peroxide (H2O2)-induced oxidative injury in osteoblasts. In primary murine and human osteoblasts, iKeap1 robustly activated Nrf2 signaling at micromole concentrations. iKeap1 disrupted Keap1-Nrf2 association, causing Nrf2 protein stabilization, cytosol accumulation and nuclear translocation in murine and human osteoblasts. The anti-oxidant response elements (ARE) activity and transcription of Nrf2-ARE-dependent genes (including HO1, NQO1 and GCLC) were increased as well. Significantly, iKeap1 pretreatment largely ameliorated H2O2-induced reactive oxygen species production, lipid peroxidation and DNA damage as well as cell apoptosis and programmed necrosis in osteoblasts. Moreover, dexamethasone- and nicotine-induced oxidative injury and apoptosis were alleviated by iKeap1. Importantly, Nrf2 shRNA or CRISPR/Cas9-induced Nrf2 knockout completely abolished iKeap1-induced osteoblast cytoprotection against H2O2. Conversely, CRISPR/Cas9-induced Keap1 knockout induced Nrf2 cascade activation and mimicked iKeap1-induced cytoprotective actions in murine osteoblasts. iKeap1 was ineffective against H2O2 in the Keap1-knockout murine osteoblasts. Collectively, iKeap1 activated Nrf2 signaling cascade to inhibit H2O2-induced oxidative injury and death of osteoblasts.