Iso-seco-tanapartholide activates Nrf2 signaling pathway through Keap1 modification and oligomerization to exert anti-inflammatory effects

• Published in: Free radical biology & medicine Vol. 178; pp. 398 - 412
• Main Authors: Zhu, Dongrong, Xia, Yuanzheng, Li, Shang, Kong, Min, Chen, Chen, Xue, Guimin, Kong, Lingyi, Luo, Jianguang
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2022
• Subjects: Anti-inflammatory; Anti-Inflammatory Agents - pharmacology; Iso-seco-tanapartholide; Keap1 dimer; Kelch-Like ECH-Associated Protein 1 - genetics; Kelch-Like ECH-Associated Protein 1 - metabolism; NF-E2-Related Factor 2 - genetics; NF-E2-Related Factor 2 - metabolism; NF-kappa B - genetics; NF-kappa B - metabolism; Nrf2; Oligomerization; Signal Transduction; NO; Oligomerization; DTT; H&E; βME; DARTS; IST; LPS; CETSA; NAC; RNA-seq; ARE; Nrf2; DEX; Keap1 dimer; ROS; Iso-seco-tanapartholide; Keap1; Anti-inflammatory; GSH; ELISA
• DOI: 10.1016/j.freeradbiomed.2021.12.259
• ISSN: 0891-5849; 1873-4596

Covalent modification of Keap1 results in reducing ubiquitination and the accumulation of Nrf2, which subsequently initiates the transcription of cellular anti-oxidant and anti-inflammatory genes. Iso-seco-tanapartholide (IST), a sesquiterpene isolated from the traditional Chinese medicine Artemisia argyi, had been reported to possess NF-κB inhibitory activity. However, its deep anti-inflammatory effects and direct target have never been reported. Here we show that IST activated Nrf2 and increased its target gene expression. In particular, LPS-caused inflammation in vitro and in vivo was mitigated by IST-induced Nrf2 activation but aggravated by Nrf2 inhibition. Mechanically, IST targeted Keap1 proteins via alkylating its cysteine residues 151, 273, 288, and so on. Subsequently, the modifying agent IST was displaced by intermolecular sulfhydryl disulfide interchange to lead to a disulfide dimer of Keap1. The resulting conformational change of Keap1 liberated Nrf2 from sequestration and allowed it translocation to the nucleus to activate the transcriptional program. Further studies demonstrated that Keap1 dimer formation contributed to the anti-inflammatory effects of IST. Taken together, our findings reveal a new mechanism for Nrf2 activation and provide a potential lead compound to treat inflammatory diseases through targeting Keap1. [Display omitted] •IST exerts anti-inflammatory effects in vitro and in vivo.•IST activates Nrf2 and its target gene expression.•IST covalently modifies Keap1 and induces its oligomerization.•IST-induced Keap1 dimer is cross-linked by intermolecular disulfide bridges.•Keap1 dimer formation contributes to the anti-inflammatory effects of IST.