PXR Functionally Interacts with NF-κB and AP-1 to Downregulate the Inflammation-Induced Expression of Chemokine CXCL2 in Mice

• Published in: Cells (Basel, Switzerland) Switzerland), 2020-10, Vol.9 (10), p.2296
• Main Authors: Okamura, Maya, Shizu, Ryota, Abe, Taiki, Kodama, Susumu, Hosaka, Takuomi, Sasaki, Takamitsu, Yoshinari, Kouichi
• Format: Article
• Language: English
• Subjects: Activator protein 1; Animals; Anti-Inflammatory Agents; AP-1; Carbon tetrachloride; Carbon Tetrachloride - pharmacology; CCL4 protein; Chemical and Drug Induced Liver Injury; chemokine; Chemokine CXCL2 - genetics; Chemokines; CXCL2; Disease Models, Animal; Experiments; Gene expression; Gene Expression Regulation; HEK293 Cells; Humans; Inflammation; Inflammation - genetics; Kinases; Laboratories; Leukocytes (neutrophilic); Liver; Liver X receptors; Male; Metabolism; Metastases; Mice; Mice, Inbred C57BL; Monocyte chemoattractant protein 1; Mutation; NF-kappa B - metabolism; NF-κB; NF-κB protein; nuclear receptor; Plasmids; Polymerase chain reaction; Pregnane X Receptor - metabolism; Pregnenolone; Pregnenolone Carbonitrile - pharmacology; Protein Binding; Proteins; PXR; Reproducibility; Reverse transcription; Transaminase; Transcription Factor AP-1 - metabolism; Transcription factors; Tumor Necrosis Factor-alpha - metabolism; Tumor necrosis factor-TNF; Tumor necrosis factor-α; Variance analysis
• ISSN: 2073-4409; 2073-4409
• DOI: 10.3390/cells9102296

Pregnane X receptor (PXR) is a liver-enriched xenobiotic-responsive transcription factor. Although recent studies suggest that PXR shows anti-inflammatory effects by suppressing nuclear factor kappa B (NF-κB), the detailed mechanism remains unclear. In this study, we aimed to elucidate this mechanism. Mice were treated intraperitoneally with the PXR agonist pregnenolone 16α-carbonitrile (PCN) and/or carbon tetrachloride (CCl ). Liver injury was evaluated, and hepatic mRNA levels were determined via quantitative reverse transcription polymerase chain reaction. Reporter assays with wild-type and mutated mouse promoter-containing reporter plasmids were conducted in 293T cells. Results showed that the hepatic expression of inflammation-related genes was upregulated in CCl -treated mice, and PCN treatment repressed the induced expression of chemokine-encoding and among the genes investigated. Consistently, PCN treatment suppressed the increased plasma transaminase activity and neutrophil infiltration in the liver. In reporter assays, tumor necrosis factor-α-induced expression was suppressed by PXR. Although an NF-κB inhibitor or the mutation of an NF-κB-binding motif partly reduced PXR-dependent suppression, the mutation of both NF-κB and activator protein 1 (AP-1) sites abolished it. Consistently, AP-1-dependent gene transcription was suppressed by PXR with a construct containing AP-1 binding motifs. In conclusion, the present results suggest that PXR exerts anti-inflammatory effects by suppressing both NF-κB- and AP-1-dependent chemokine expression in mouse liver.