Lipopolysaccharide Induces Matrix Metalloproteinase-9 Expression via a Mitochondrial Reactive Oxygen Species-p38 Kinase-Activator Protein-1 Pathway in Raw 264.7 Cells

• Published in: The Journal of immunology (1950) Vol. 173; no. 11; pp. 6973 - 6980
• Main Authors: Woo, Chang-Hoon, Lim, Jae-Hyang, Kim, Jae-Hong
• Format: Journal Article
• Language: English
• Published: United States Am Assoc Immnol 01.12.2004
• Subjects: Acetophenones - pharmacology; Animals; Benzopyrans - pharmacology; Cell Line; Enzyme Induction - drug effects; Enzyme Induction - genetics; Enzyme Induction - immunology; Enzyme Inhibitors - pharmacology; Gene Expression Regulation - immunology; Isoenzymes - physiology; Lipopolysaccharides - antagonists & inhibitors; Lipopolysaccharides - pharmacology; Macrophages - drug effects; Macrophages - enzymology; Macrophages - immunology; Matrix Metalloproteinase 9 - biosynthesis; Matrix Metalloproteinase 9 - genetics; Matrix Metalloproteinase Inhibitors; Mice; Mitochondria - enzymology; Mitochondria - metabolism; Mitochondria - physiology; NF-kappa B - physiology; p38 Mitogen-Activated Protein Kinases - biosynthesis; p38 Mitogen-Activated Protein Kinases - physiology; Promoter Regions, Genetic; Protein Kinase C - physiology; Protein Kinase C-delta; Reactive Oxygen Species - metabolism; Signal Transduction - drug effects; Signal Transduction - genetics; Signal Transduction - immunology; Transcription Factor AP-1 - metabolism; Transcription Factor AP-1 - physiology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.173.11.6973

We have identified a novel signaling pathway that leads to expression of matrix metalloproteinase-9 (MMP-9) in murine macrophages in response to the bacterial endotoxin, LPS. We showed that p38 kinase was essential for this induction and observed that LPS-induced MMP-9 expression was sensitive to rottlerin, a putative protein kinase Cdelta (PKCdelta) inhibitor. However neither infection with a retrovirus expressing a dominant negative mutant of PKCdelta nor down-regulation of PKCdelta by prolonged PMA treatment affected MMP-9 expression, thus excluding involvement of PKCdelta. Interestingly, LPS-induced MMP-9 expression and p38 kinase phosphorylation were shown to be suppressed by the antioxidant N-acetylcysteine and the flavoenzyme inhibitor diphenyleneiodonium chloride, but not by pyrrolidine dithiocarbamate, an NF-kappaB inhibitor. In addition, LPS was found to induce the production of mitochondrial reactive oxygen species (ROS) and this effect was rottlerin-sensitive, suggesting an inhibitory effect of rottlerin on mitochondrial ROS. LPS-induced MMP-9 expression and p38 kinase phosphorylation were also inhibited by rotenone, a specific inhibitor of mitochondrial complex I, supporting the role of mitochondrial ROS in LPS signaling to MMP-9. Finally, we showed that the ROS-p38 kinase cascade targets the transcription factor AP-1. Taken together, our findings identify a ROS-p38 kinase-AP-1 cascade as a novel pathway mediating LPS signaling to MMP-9 expression in macrophages.