Fractalkine-mediated signals regulate cell-survival and immune-modulatory responses in intestinal epithelial cells.
BACKGROUND & AIMS: In this study, we determined the signal transduction and functional consequences after ligand-specific activation of the fractalkine receptor CX3CR1 in human intestinal epithelial cells. METHODS: CX3CR1 expression in human colonic tissues and intestinal epithelial cell lines was determined by immunohistochemistry, immunoblotting, and reverse-transcription polymerase chain reaction. The regulation of mitogen-activated protein kinase ( MAPK) activation was assessed by immunoblotting. Regulation of chemokine messenger RNA (mRNA) expression was determined by Northern blotting. NF-kappa B and p53 activation was assessed by electromobility shift assays. RESULTS: Fractalkine mediated the MEK-1 and G alpha i-dependent but phosphatidylinositol-3-kinase-independent activation of extracellular signal-regulated kinase- MAPK. Fractalkine activated NF-kappa B and p53 resulting in interleukin 8 and fractalkine mRNA expression. CX3CR1-mediated activation of intestinal epithelial cells was able to induce migration of human neutrophils into but not through the intestinal epithelial cell monolayer. CONCLUSIONS: CX3CR1 mediates distinct functional responses in intestinal epithelial cells, which include the autocrine regulation of cell-survival signals and activation of immune modulators, indicating a role of CX3CR1 in host defense mechanisms originating from the intestinal epithelium.[1]References
- Fractalkine-mediated signals regulate cell-survival and immune-modulatory responses in intestinal epithelial cells. Brand, S., Sakaguchi, T., Gu, X., Colgan, S.P., Reinecker, H.C. Gastroenterology (2002) [Pubmed]
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