Insulin-induced NADPH oxidase activation promotes proliferation and matrix metalloproteinase activation in monocytes/macrophages.
Insulin stimulates superoxide (O(2)(-)) production in monocytes and macrophages. However, the mechanisms through which insulin induces O(2)(-) production are not completely understood. In this study, we (a) characterized the enzyme and the pathways involved in insulin-stimulated O(2)(-) production in human monocytes and murine macrophages, and (b) analyzed the consequences of insulin-stimulated O(2)(-) production on the cellular phenotype in these cells. We showed that insulin stimulated O(2)(-) production, and promoted p47(phox) translocation to the plasma membrane. Insulin-induced O(2)(-) production and p47(phox) translocation were prevented in the presence of specific inhibitors of PI3K and PKC. Insulin-mediated NADPH oxidase activation stimulated MMP-9 activation in monocytes and cell proliferation in macrophages. The effect of insulin on these phenotypic responses was mediated through NFkappaB, p38MAPK, and ERK 1/2 activation. Small-interfering RNA-specific gene silencing targeted specifically against Nox2 reduced the cognate protein expression, decreased insulin-induced O(2)(-) production, inhibited the turn on of NFkappaB, p38MAPK, and ERK 1/2, and reduced cell proliferation in macrophages. These findings suggest a pivotal role for NADPH oxidase in insulin-induced proliferation and proteolytic activation in monocytes and macrophages, respectively, and identify a pathway that may play a pathological role in hyperinsulinemic states.
Division of Cardiovascular Sciences, Center for Applied Medical Research, University of Navarra, Pamplona, Spain.
Gorka
G
San José
Julen
J
Bidegain
Pablo A
PA
Robador
Javier
J
Díez
Ana
A
Fortuño
Guillermo
G
Zalba
D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D002478:Cells, Cultured; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009000:Monocytes / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D021381:Protein Transport / Q000187:drug effects; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013481:Superoxides / Q000737:chemistry / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors
D004791:Enzyme Inhibitors; D007328:Insulin; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D000081082:Phosphoinositide-3 Kinase Inhibitors; D034741:RNA, Small Interfering; D013481:Superoxides; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020780:Matrix Metalloproteinase 9