c-Jun N-terminal kinase and p38 mitogen-activated protein kinase mediate double-strand RNA-induced inducible nitric oxide synthase expression in microglial cells.
Double-stranded RNA (dsRNA) has been implicated as a potential immune stimulant in activating microglia, which can cause chronic neurodegeneration. In this study, we examined the involvement of different types of mitogen-activated protein kinases (MAPKs) in the induction of inducible nitric oxide synthase (iNOS) by dsRNA in microglial cells. Nitric oxide production was increased after exposure of microglia to 50mug/mL dsRNA. Levels of dsRNA-induced nitrite production in a line of immortalized murine microglia (BV2) and in primary cultures of murine microglia were decreased by inhibition of JNK or p38 MAPK, but were increased by inhibition of extracellular signal-regulated kinase. Similar results were shown in the levels of dsRNA-induced iNOS gene expression in BV2 cells. Phosphorylation levels of p38 MAPK were increased, depending on p38 MAPK inhibitor concentrations, while activation levels of MAPKAPK2, a known p38 substrate, were inhibited. Thus, it is likely that SB203580 inhibited the kinase activity of p38 MAPK, resulting in the loss of a feedback inhibition regulatory loop of p38 MAPK in BV2 cells. These findings suggest that dsRNA stimulated iNOS expression via MAPK signaling pathways, including JNK and p38 MAPK.
Kong
Pil-Jae
PJ
Department of Pharmacology, College of Medicine, Kangwon National University, 192-1 Hyoja 2-Dong, Chunchon, Kangwon-Do 200-701, Republic of Korea.
Lee
Hee Jae
HJ
Lee
Sang-Hyun
SH
Kim
Su Young
SY
Lee
Su Nam
SN
Chun
Wan-Joo
WJ
Kim
Sung-Soo
SS
D000818:Animals; D002461:Cell Line, Transformed; D004791:Enzyme Inhibitors / Q000494:pharmacology; D025461:Feedback, Physiological / Q000187:drug effects / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000235:genetics; D005911:Gliosis / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics; D051379:Mice; D017628:Microglia / Q000187:drug effects / Q000201:enzymology*; D009569:Nitric Oxide / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D012330:RNA, Double-Stranded / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D004791:Enzyme Inhibitors; D012330:RNA, Double-Stranded; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases