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Title: Keap1 silencing boosts lipopolysaccharide-induced transcription of interleukin 6 via activation of nuclear factor κB in macrophages

Interleukin-6 (IL6) is a multifunctional cytokine that regulates immune and inflammatory responses. Multiple transcription factors, including nuclear factor κB (NF-κB) and nuclear factor E2-related factor 2 (Nrf2), regulate IL6 transcription. Kelch-like ECH-associated protein 1 (Keap1) is a substrate adaptor protein for the Cullin 3-dependent E3 ubiquitin ligase complex, which regulates the degradation of many proteins, including Nrf2 and IκB kinase β (IKKβ). Here, we found that stable knockdown of Keap1 (Keap1-KD) in RAW 264.7 (RAW) mouse macrophages and human monocyte THP-1 cells significantly increased expression of Il6, and Nrf2-target genes, under basal and lipopolysaccharide (LPS, 0.001–0.1 μg/ml)-challenged conditions. However, Nrf2 activation alone, by tert-butylhydroquinone treatment of RAW cells, did not increase expression of Il6. Compared to cells transduced with scrambled non-target negative control shRNA, Keap1-KD RAW cells showed enhanced protein levels of IKKβ and increased expression and phosphorylation of NF-κB p65 under non-stressed and LPS-treated conditions. Because the expression of Il6 in Keap1-KD RAW cells was significantly attenuated by silencing of Ikkβ, but not Nrf2, it appears that stabilized IKKβ is responsible for the enhanced transactivation of Il6 in Keap1-KD cells. This study demonstrated that silencing of Keap1 in macrophages boosts LPS-induced transcription of Il6 via NF-κB activation. Given themore » importance of IL6 in the inflammatory response, the Keap1–IKKβ–NF-κB pathway may be a novel target for treatment and prevention of inflammation and associated disorders. - Highlights: • Knockdown of Keap1 increases expression of Il6 in macrophages. • Silencing of Keap1 results in protein accumulation of IKKβ and NF-κB p65. • Induction of Il6 resulting from Keap1 silencing is attributed to NF-κB activation.« less
 [1] ;  [2] ; ;  [3] ;  [3] ;  [4] ;  [3] ;  [1] ;  [5] ;  [6] ;  [7] ; ;  [3] ;  [3]
  1. Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing (China)
  2. (United States)
  3. Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709 (United States)
  4. (China)
  5. Institute for Medical Device Standardization Administration, National Institutes for Food and Drug Control, Beijing (China)
  6. Evaluation and Research Center for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences (China)
  7. Key Laboratory of the Public Health Safety, Ministry of Education, School of Public Health, Fudan University, Shanghai (China)
Publication Date:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Toxicology and Applied Pharmacology; Journal Volume: 272; Journal Issue: 3; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States