Activation of p38 MAPK induced peroxynitrite generation in LPS plus IFN-gamma-stimulated rat primary astrocytes via activation of iNOS and NADPH oxidase.
We have shown that immunostimulated astrocytes produce excess nitric oxide (NO) and eventually peroxynitrite (ONOO(-)) that was closely associated with the glucose deprivation-potentiated death of astrocytes. The present study shows that activated p38 MAPK regulates ONOO(-) generation from lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma)-stimulated astrocytes. LPS+IFN-gamma-induced p38 MAPK activation and ONOO(-) generation were attenuated by SB203580 or SKF-86002, specific inhibitors of p38 MAPK. ONOO(-) generation was blocked by NADPH oxidase inhibitor, diphenyleneiodonium chloride, and nitric oxide synthase (NOS) inhibitor, N omega-nitro-L-arginine methyl ester, suggesting both enzymes are involved in ONOO(-) generation. Inhibition of p38 MAPK suppressed LPS+IFN-gamma-induced NO production through down-regulating inducible form of NOS expression. It also suppressed LPS+IFN-gamma-induced NADPH oxidase activation and eventually, the inducible form of superoxide production. Transfection with dominant negative vector of p38 alpha reduced LPS+IFN-gamma-induced ONOO(-) generation through blocking both iNOS-derived NO production and NADPH oxidase-derived O2(-) production. Our results suggest that activated p38 MAPK may serve as a potential signaling molecule in ONOO(-) generation through dual regulatory mechanisms, involving iNOS induction and NADPH oxidase activation.
Yoo
Byoung Kwon
BK
Department of Pharmacology, College of Pharmacy, Seoul National University, San 56-1, Shinlim-Dong, Kwanak-Gu, Seoul 151-742, Republic of Korea.
Choi
Ji Woong
JW
Shin
Chan Young
CY
Jeon
Se Jin
SJ
Park
Seo Jin
SJ
Cheong
Jae Hoon
JH
Han
Sun Young
SY
Ryu
Jae Ryun
JR
Song
Mi Ryoung
MR
Ko
Kwang Ho
KH
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D004660:Encephalitis / Q000201:enzymology* / Q000276:immunology / Q000503:physiopathology; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007371:Interferon-gamma / Q000276:immunology / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D019255:NADPH Oxidases / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D030421:Peroxynitrous Acid / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II; D019255:NADPH Oxidases; D048051:p38 Mitogen-Activated Protein Kinases