Induction of inducible nitric oxide synthase-NO* by lipoarabinomannan of Mycobacterium tuberculosis is mediated by MEK1-ERK, MKK7-JNK, and NF-kappaB signaling pathways.
Nitric oxide (NO*) expression by inducible nitric oxide synthase (iNOS) is an important host defense mechanism against Mycobacterium tuberculosis in mononuclear phagocytes. The objective of this investigation was to examine the role of mitogen-activated protein (MAP) kinase (MAPK) and nuclear factor kappaB (NF-kappaB) signaling pathways in the regulation of iNOS and NO* by a mycobacterial cell wall lipoglycan known as mannose-capped lipoarabinomannan (ManLAM). Specific pharmacologic inhibition of the extracellular-signal-regulated kinase (ERK) or NF-kappaB pathway revealed that both these signaling cascades were required in gamma interferon (IFN-gamma)-ManLAM-induced iNOS protein and NO2- expression in mouse macrophages. Transient cotransfection of dominant-negative protein mutants of the c-Jun NH2-terminal kinase (JNK) pathway revealed that the MAP kinase kinase 7 (MKK7)-JNK cascade also mediated IFN-gamma-ManLAM induction of iNOS promoter activity whereas MKK4 did not. Overexpression of null mutant IkappaBalpha, a potent inhibitor of NF-kappaB activation, confirmed that the IkappaBalpha kinase (IKK)-NF-kappaB signaling pathway enhanced IFN-gamma-ManLAM-induced iNOS promoter activity. By contrast, activated p38mapk inhibited iNOS induction. These results indicate that combined IFN-gamma and ManLAM stimulation induced iNOS and NO. expression and that MEK1-ERK, MKK7-JNK, IKK-NF-kappaB, and p38mapk signaling pathways play important regulatory roles.
Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center, Denver, Colorado, USA. chane@njc.org
E D
ED
Chan
K R
KR
Morris
J T
JT
Belisle
P
P
Hill
L K
LK
Remigio
P J
PJ
Brennan
D W
DW
Riches
D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000502:physiology; D004790:Enzyme Induction; D020672:I-kappa B Proteins; D007371:Interferon-gamma / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D008070:Lipopolysaccharides / Q000494:pharmacology*; D048369:MAP Kinase Kinase 1; D048688:MAP Kinase Kinase 7; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000502:physiology*; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases
D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; C050016:lipoarabinomannan; D000072000:NF-KappaB Inhibitor alpha; D009569:Nitric Oxide; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048688:MAP Kinase Kinase 7; C482127:Map2k1 protein, mouse; C482570:Map2k7 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases