Tumor necrosis factor-alpha induces expression of monocyte chemoattractant JE via fos and jun genes in clonal osteoblastic MC3T3-E1 cells.
The mechanism by which circulating monocytes are attracted to sites of bone remodeling is unknown. We now report that tumor necrosis factor-alpha ( TNF-alpha), a potent osteotrophic cytokine, was stimulatory for expression of the monocyte chemoattractant JE gene in osteoblastic MC3T3-E1 cells. TNF-alpha stimulated this JE gene expression transcriptionally. The presence of JE gene product in conditioned medium of the cytokine-treated cells was evidenced by an immunoprecipitation assay with antiserum specific for JE/ MCP-1. The stimulated JE gene expression was markedly inhibited by H-7, a potent inhibitor of protein kinase C. Phorbol 12-myristate 13-acetate induced the JE gene expression, and the cytokine-induced JE gene expression was down-regulated by the phorbol ester pretreatment. TNF-alpha induced expression of both early protooncogenes, c-fos and c-jun, in the cells. Antisense oligonucleotides to these oncogenes significantly inhibited the cytokine-induced monocyte chemotactic activity. Furthermore, curcumin, a specific inhibitor of c-jun/ AP-1, markedly inhibited JE gene expression and monocyte chemotactic activity induced by the cytokine. These results suggest that TNF-alpha may contribute to the regulation of remodeling and inflammation of bone tissues through the JE gene product.[1]References
- Tumor necrosis factor-alpha induces expression of monocyte chemoattractant JE via fos and jun genes in clonal osteoblastic MC3T3-E1 cells. Hanazawa, S., Takeshita, A., Amano, S., Semba, T., Nirazuka, T., Katoh, H., Kitano, S. J. Biol. Chem. (1993) [Pubmed]
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