RETINOIC ACID SUPPRESSION OF C-FOS GENE INHIBITS EXPRESSION OF TUMOR NECROSIS FACTOR-ALPHA-INDUCED MONOCYTE CHEMOATTRACTANT JE/MCP-1 IN CLONAL OSTEOBLASTIC MC3T3-E1 CELLS

Our previous study (Hanazawa, S., Takeshita, k, Amano, S., Semba, T., Nirazuka, T., Katoh, H., and Kitano, S. (1993) J. Biol. Chem. 268, 9526-9532) demonstrated that tumor necrosis factor-cu (TNF-cu) induces monocyte chemoattractant JE/MCP-1 expression via c-fos and c-jun genes following protein kinase C activation in osteoblastic MC3T3-E1 cells. In the present study, we examined the effect of retinoic acid (RA) on the cytokine-induced JE/MCP-1 expression in the cells. RA significantly inhibited the JE/MCP-1 gene expression by at least 6 h of pretreatment, and the inhibition was pretreatment time-dependent and occurred at the transcriptional level of the JE/MCP-1 gene expression. The RA-induced inhibition of the JE/MCP-1 gene product was also evidenced by both an assay involving immuno-precipitation with JE/MCP-1-specific antiserum and an assay for monocyte chemotaxis. Also, RA stimulated the gene expression of three different subclasses of RA receptor. RA pretreatment transcriptionally suppressed the expression of the c-fos gene but not that of the c-jun gene in TNF-alpha-treated cells. Antisense oligonucleotide to c-fos gene inhibited the cytokine-induced JE/MCP-1 gene expression in the cells. Furthermore, RA inhibited activator protein-1 binding to 12-O-tetradecanoylphorbol 13-acetate-response element (TRE) in the cells treated with TNF-alpha, suggesting that RA acts as a potent negative regulator for activator protein-1 binding activity to TRE in the osteoblastic cells.