Gene Expression Profiling of LPS-Stimulated Murine Macrophages and Role of the NF-κB and PI3K/mTOR Signaling Pathways

摘要

Lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria, activates a broad spectrum of signaling pathways in immune cells. In this article, RAW264.7 cells have been stimulated for 4 h with 1 μg/mL of LPS in the presence or not of specific inhibitors of the NF-κB pathway (BAY 11-7082) and the PI3K pathway (LY294002). Gene expression profiles were characterized us ing the DNA microarray "Dual Chip Mouse Inflammation." This array monitors the expression of 233 genes encoding proteins playing a role in inflammation. Both signaling pathways exert an important role in the response to LPS, but they are not completely overlapping. For example, genes encoding the PAF receptor, PAI-1, PlA2 (group V), IL-13 recep tor (α2), and GTP cyclohydrolase 1, were upregulated after LPS treat ment, but this upregulation was counteracted by LY294002. The same was observed for BAY 11-7082 : genes encoding the kit ligand, TLR2, or TNFRSF5 were mainly under the control of NF-κB. NF-κB plays an im portant role in the macrophage response to LPS, but we have also shown that the PI3K pathway partially contributes to it. Further experiments with the specific inhibitor of mTOR (rapamycin) will provide more in formation on the specific contribution of the PI3K/mTOR pathway in the inflammatory response in LPS-stimulated macrophages.