Transcriptional complex formation of c-Fos, STAT3, and hepatocyte NF-1 alpha is essential for cytokine-driven C-reactive protein gene expression.
C-reactive protein (CRP) is a sensitive marker and mediator of inflammation, whereas IL-6 blocking therapy can normalize serum levels of CRP in chronic inflammatory diseases. We investigated the precise synergistic induction mechanism of CRP gene expression by IL-1 and IL-6 in Hep3B cells. In the early induction phase, IL-1 inhibited IL-6-mediated CRP gene expression, and NF-kappaB p65 inhibited the luciferase activity of pGL3-CRP by IL-1 plus IL-6 even in the presence of overexpressed STAT3. In the late induction phase, we focused on JNK and p38 activated by IL-1. SP600125 reduced the expression of the CRP gene induced by IL-1 plus IL-6. Unexpectedly, overexpression of c-Fos dramatically enhanced the luciferase activity by IL-1 and IL-6 even though the CRP gene has no AP-1 response element (RE) in its promoter. The augmentative effect of c-Fos required the presence of STAT3 and 3'-hepatocyte NF-1 (HNF-1) RE, which were eliminated by dominant negative STAT3 and HNF-1alpha, respectively. SB203580 inhibited the phosphorylation of c-Fos enhanced by IL-1 plus IL-6, and diminished expression of the CRP gene. Immunoprecipitation, Western blot analysis, the Supershift assay using a CRP oligonucleotide containing STAT3 and 3'-HNF-1 RE, and the chromatin immunoprecipitation assay demonstrated that c-Fos/STAT3/HNF-1alpha forms a complex on the CRP gene promoter. Because human fetus liver cells failed to express c-Fos/STAT3/HNF-1alpha showed no CRP production, transcriptional complex formation of c-Fos/STAT3/HNF-1alpha is essential for the synergistic induction of CRP gene expression by IL-1 plus IL-6. Our findings fully explain the clinical results of IL-6 blocking therapy and are expected to contribute to the development of a therapeutic strategy for chronic inflammatory diseases.
Nishikawa
Teppei
T
Health Care Center, Osaka University, Department of Respiratory Medicine, Allergy, Rheumatic Diseases, Graduate School of Medicine, Osaka, Japan.
Hagihara
Keisuke
K
Serada
Satoshi
S
Isobe
Tomoyasu
T
Matsumura
Atsumi
A
Song
Jian
J
Tanaka
Toshio
T
Kawase
Ichiro
I
Naka
Tetsuji
T
Yoshizaki
Kazuyuki
K
D000873:Anthracenes / Q000494:pharmacology; D002097:C-Reactive Protein / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D002460:Cell Line; D045744:Cell Line, Tumor; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D051538:Hepatocyte Nuclear Factor 1-alpha / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007375:Interleukin-1 / Q000502:physiology; D015850:Interleukin-6 / Q000502:physiology; D016328:NF-kappa B / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology; D050796:STAT3 Transcription Factor / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D018808:Transcription Factor AP-1 / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects / Q000276:immunology*; D000093242:Interleukin-6 Inhibitors
D000873:Anthracenes; D002097:C-Reactive Protein; D016207:Cytokines; D051538:Hepatocyte Nuclear Factor 1-alpha; D007093:Imidazoles; D007166:Immunosuppressive Agents; D007375:Interleukin-1; D015850:Interleukin-6; D016328:NF-kappa B; D047428:Protein Kinase Inhibitors; D016760:Proto-Oncogene Proteins c-fos; D011725:Pyridines; D050796:STAT3 Transcription Factor; D018808:Transcription Factor AP-1; D000093242:Interleukin-6 Inhibitors; C494086:STAT3 protein, human; C432165:pyrazolanthrone; C093642:SB 203580