Multiple transcription factors regulating the IL-6 gene are activated by cAMP in cultured Caco-2 cells

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2002-11, Vol.283 (5), p.1140-R1148
• Main Authors: Hershko, Dan D, Robb, Bruce W, Luo, Guangju, Hasselgren, Per-Olof
• Format: Article
• Language: English
• Subjects: Blotting, Western; Caco-2 Cells; CCAAT-Enhancer-Binding Proteins - genetics; Cell Survival - physiology; Chlorides - metabolism; Cholecystokinin - metabolism; Cyclic AMP - pharmacology; Cyclic AMP Response Element-Binding Protein - genetics; Gastrointestinal Hormones - metabolism; Gene Expression Regulation - physiology; Humans; Interleukin-6 - genetics; Intestinal Mucosa - metabolism; Luciferases - metabolism; Mitogen-Activated Protein Kinases - metabolism; NF-kappa B - genetics; Signal Transduction - physiology; Transcription Factor AP-1 - genetics; Transcription Factors - physiology; Transfection
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00161.2002

Department of Surgery, University of Cincinnati, Cincinnati, Ohio 45267; and the Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215 Mucosal and enterocyte IL-6 production is increased during sepsis and endotoxemia. Recent studies suggest that cAMP potentiates IL-6 production in endotoxin- or IL-1 -stimulated enterocytes, but the molecular mechanisms are not known. We examined the role of the transcription factors NF- B, activator protein (AP)-1, CCAAT/enhancer binding protein (C/EBP), and cAMP response element-binding protein (CREB) in cAMP-induced IL-6 production in cultured Caco-2 cells, a human intestinal epithelial cell line. In addition, the role of the protein kinase A (PKA), protein kinase C (PKC), and mitogen-activated protein (MAP) kinase signaling pathways was examined. Treatment of the cells with IL-1 increased IL-6 production and activated the IL-6 promoter in cells transfected with a luciferase reporter plasmid containing a wild-type IL-6 promoter. These effects of IL-1 were significantly potentiated by cAMP. When the binding sites for the individual transcription factors in the IL-6 promoter were mutated, results indicated that all four transcription factors may be involved in the cAMP-induced activation of the IL-6 gene. Treatment of the Caco-2 cells with cAMP increased the DNA binding activity of CREB, C/EBP, and AP-1, but not NF- B. By using specific blockers, evidence was found that both PKA and p38 MAP kinase (but not PKC or p42/44 MAP kinase) may be involved in the cAMP-induced potentiation of IL-6 production. The present results suggest that cAMP activates multiple transcription factors involved in the regulation of the IL-6 gene and that the activation of these transcription factors may at least in part explain why cAMP potentiates IL-6 production in stimulated enterocytes. mucosa; inflammation; cytokines; mitogen-activated protein kinase