title: Redox/ROS regulation of lipopolysaccharide-induced mitogen-activated protein kinase (MAPK) activation and MAPK-mediated TNF-alpha biosynthesis.
abstract: Redox and ROS regulation of MAPK-mediated TNF-alpha biosynthesis is not well characterized. It was hypothesized that the involvement of the MAPK pathway in regulating LPS-mediated TNF-alpha secretion is redox-dependent, NF-kappaB-sensitive and attenuated by N-acetyl-L-cysteine (NAC) and other antioxidants. In alveolar epithelial cells, LPS induced a time- and dose-dependent phosphorylation of MAPK(p38). This was associated with the activation of MAPK-activated protein kinase, which phosphorylated the small heat-shock protein, Hsp27. MAPK(p38) inhibition (SB-203580) abrogated LPS-induced TNF-alpha production. MAPK(ERK) blockade (PD-98059) attenuated TNF-alpha secretion, an effect synergistically amplified in the presence of SB-203580. Regulation of NF-kappaB by selective inhibitors revealed that this pathway is partially involved in regulating LPS-mediated TNF-alpha secretion. Whereas the proteasome inhibitor, MG-132, had no effect on LPS-mediated TNF-alpha production, CAPE, sulfasalazine and SN-50, a cell-permeant NF-kappaB inhibitor, attenuated but did not abrogate TNF-alpha biosynthesis. LPS up-regulated ROS, an effect abrogated by 4'-hydroxy-3'-methoxy-acetophenone and NAC, which reduced TNF-alpha secretion, induced the accumulation of GSH, reduced the concentration of GSSG, and blockaded the phosphorylation/activation of MAPK(p38) pathway. ROS induced MAPK(p38) phosphorylation and selective antioxidants, including the permeant GSH precursor, gamma-GCE, reduced ROS-dependent MAPK(p38) phosphorylation. These results indicate that the MAPK pathway and MAPK-mediated regulation of TNF-alpha production is redox-dependent, GSH-mediated and requires, at least in part, a NF-kappaB/ROS-sensitive mechanism.
authors.affiliation: Oxygen Signalling Group, Centre for Research into Human Development, Tayside Institute of Child Health, Faculty of Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY. haddadj@anesthesia.ucsf.edu
authors.forename: J J
authors.initials: JJ
authors.lastname: Haddad
authors.forename: S C
authors.initials: SC
authors.lastname: Land
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D046508:Culture Techniques; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005260:Female; D005978:Glutathione / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D010084:Oxidation-Reduction; D010766:Phosphorylation / Q000187:drug effects; D011247:Pregnancy; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2
chemical_list: D000111:Acetylcysteine; D005978:Glutathione; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides; D020928:Mitogen-Activated Protein Kinases; D017346:Protein Serine-Threonine Kinases; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2