Secretion of matrix metalloproteinase-9 by the proinflammatory cytokine, IL-1beta: a role for the dual signalling pathways, Akt and Erk.
BACKGROUND
Matrix metalloproteinases including MMP-9 mediate matrix destruction during chronic inflammatory diseases such as arthritis and atherosclerosis. MMP-9 up-regulation by inflammatory cytokines involve interactions between several transcription factors including activator protein-1 and NFkappaB. The upstream regulatory pathways are less well understood.


RESULTS
To search for the mechanism of tissue destruction in the process of inflammatory disorders, we investigated the signalling pathway critical for the activation of MMP-9 expression and secretion by IL-1beta. Treatment of Balb 3T3 cells with IL-1beta activated MMP-9 transcription and subsequent secretion in a time- and dose-dependent manner. Concomitantly, IL-1beta treatment of cells activated phosphorylation of Akt, Erk and p38. Treatment of cells with either LY294002, a PI3K inhibitor, or expression of a dominant negative form of Akt drastically suppressed the IL-1beta-dependent secretion of MMP-9. Pretreatment of cells with a MEK1 inhibitor, U0126, also strongly inhibited IL-1beta-dependent secretion of MMP-9. In contrast, pre-treatment with a specific p38 kinase inhibitor, SB203580, had no effect on IL-1beta-dependent secretion of MMP-9. In addition, cells expressing constitutively active form of Akt or MEK1 showed no clear activation of MMP-9 secretion, whereas these cells responded well to IL-1beta treatment. However, co-transfection of cells with both active Akt and MEK1 was sufficient to induce MMP-9 secretion without stimulation with IL-1beta.


CONCLUSIONS
Taken together, our results suggest that IL-1beta stimulation of cells activates MMP-9 secretion by the activation of the dual signalling pathways, the PI3K-Akt and MEK1-Erk and constitutive activation of these pathways were sufficient to induce MMP-9 secretion.
Ruhul Amin
A R M
AR
Laboratory of Molecular Pathogenesis, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
Senga
Takeshi
T
Oo
Myat Lin
ML
Thant
Aye Aye
AA
Hamaguchi
Michinari
M
D000818:Animals; D041702:BALB 3T3 Cells; D002070:Butadienes / Q000494:pharmacology; D002867:Chromones / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D005799:Genes, Dominant; D007093:Imidazoles / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology*; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases
D002070:Butadienes; D002867:Chromones; D004791:Enzyme Inhibitors; D007093:Imidazoles; D007375:Interleukin-1; D009025:Morpholines; D009570:Nitriles; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D011725:Pyridines; C113580:U 0126; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020780:Matrix Metalloproteinase 9; C093642:SB 203580