Glucocorticoid-mediated Gene Suppression of Rat Cytokine-induced Neutrophil Chemoattractant CINC/gro, a Member of the Interleukin-8 Family, through Impairment of NF-κB Activation (∗)

• Published in: The Journal of biological chemistry 1996-01, Vol.271 (3), p.1651-1659
• Main Authors: Ohtsuka, Toshiaki, Kubota, Atsushi, Hirano, Takae, Watanabe, Kazuyoshi, Yoshida, Hideaki, Tsurufuji, Makoto, Iizuka, Yoshio, Konishi, Kiyoshi, Tsurufuji, Susumu
• Format: Article
• Language: English
• Subjects: Animals; Base Sequence; Blotting, Northern; Cell Division - drug effects; Cell Line; Cell Nucleus - metabolism; Chemokine CXCL1; Chemokines, CXC; Chemotactic Factors - biosynthesis; Chemotactic Factors - pharmacology; Cytokines - pharmacology; Dexamethasone - pharmacology; Gene Expression - drug effects; Growth Inhibitors - biosynthesis; Growth Inhibitors - pharmacology; Growth Substances - biosynthesis; Growth Substances - pharmacology; Humans; Intercellular Signaling Peptides and Proteins; Interleukin-1 - pharmacology; Interleukin-8 - biosynthesis; Interleukin-8 - pharmacology; Kidney; Kinetics; Luciferases - biosynthesis; Melanoma - pathology; Molecular Sequence Data; NF-kappa B - drug effects; NF-kappa B - metabolism; Oligonucleotide Probes; Rats; Recombinant Fusion Proteins - biosynthesis; Recombinant Proteins - pharmacology; RNA, Messenger - analysis; RNA, Messenger - biosynthesis; Suppression, Genetic - drug effects; Transcription, Genetic - drug effects; Transfection; Tumor Necrosis Factor-alpha - pharmacology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.271.3.1651

The glucocorticoid dexamethasone inhibited the production of the rat cytokine-induced neutrophil chemoattractant CINC/gro, a counterpart of human melanoma growth-stimulating activity that belongs to the interleukin-8 (IL-8) family, in the normal rat kidney epithelial cell line NRK-52E stimulated with interleukin-1β (IL-1β), lipopolysaccharide, or tumor necrosis factor α. The accumulation of CINC/gro mRNA induced by these activators was also decreased comparably by dexamethasone. A nuclear run-on assay revealed that dexamethasone decreased the IL-1β-induced transcription of the CINC/gro gene. The half-life of CINC/gro mRNA transcripts did not change significantly after exposure to dexamethasone, suggesting that this glucocorticoid acts mainly at the transcriptional level. Transfection with luciferase expression vectors containing 5′-deleted and mutated CINC/gro gene sequences demonstrated that the 5′-flanking region containing the NF-κB binding site is involved in the IL-1β- and dexamethasone-induced activation and repression of the CINC/gro gene expression, respectively. Furthermore, a tandem repeat of the NF-κB sequence in the CINC/gro gene conferred the inducibility by IL-1β and suppression of luciferase activity by dexamethasone. In an electrophoretic mobility shift assay, dexamethasone diminished the IL-1β-induced formation of NF-κB complexes, which consisted of p65 and p50. Western blotting revealed that dexamethasone inhibited the IL-1β-induced translocation of p65 from the cytoplasm into the nucleus, while the nuclear level of NF-κB p50 remained almost unchanged. In addition, the degradation of IκB-α induced by IL-1β was not inhibited by dexamethasone. These results indicated that the suppression of the CINC/gro gene transcription by glucocorticoid occurs through the impairment of NF-κB activation, possibly by interference with the translocation of NF-κB p65 from the cytoplasm into the nucleus, thereby suppressing transactivation of the CINC/gro gene.