Selective modulation of lipopolysaccharide-stimulated cytokine expression and mitogen-activated protein kinase pathways by dibutyryl-cAMP in BV2 microglial cells.
Cyclic AMP is a very important regulator in a wide range of biological processes, including inflammatory reactions. To investigate the role of cAMP in microglia, we examined the effect of dibutyryl-cAMP (dbcAMP) on lipopolysaccharide (LPS)-stimulated cytokine expression and signaling pathways in murine BV2 microglial cells. DbcAMP strongly suppressed LPS-induced TNF-alpha expression, without affecting NO, IL-6 or TGF-beta1 expression. In contrast, LPS-induced IL-1beta or IL-10 expressions were dramatically increased by dbcAMP. We further examined the effect of elevated cAMP on signaling molecules such as MAP kinases (p38 MAPK, ERK and JNK), NF-kappaB and AP1, which are involved in the regulation of inflammatory responses. DbcAMP decreased the LPS-induced phosphorylation of p38 MAPK, while it modestly enhanced the ERK activity. JNK phosphorylation was slightly reduced by dbcAMP only at the later time point. Electrophoretic mobility shift assay revealed that the elevated cAMP potentiated AP-1 binding activity by enhancing c-fos binding. On the other hand, dbcAMP repressed NF-kappaB-mediated transcription without affecting NF-kappaB binding. Treatment with H89, a selective inhibitor of protein kinase A, completely reversed cAMP-induced IL-10 and IL-1beta upregulation but only partially reversed the cAMP-induced repression of TNF-alpha. Thus, the effect of dbcAMP in BV2 cells appears to be mediated through both protein kinase A-dependent and -independent pathways. Taken together, our results demonstrate that cAMP modulates microglia activation in a diverse and complex manner.
Department of Neuroscience, Ewha Institute of Neuroscience, College of Medicine, Ewha Womans University, 70 Jongno 6-Ga, Jongno-Gu, Seoul 110-783, South Korea.
Moon-Sook
MS
Woo
Pil-Geum
PG
Jang
Jin-Sun
JS
Park
Won-Ki
WK
Kim
Tong H
TH
Joh
Hee-Sun
HS
Kim
D000818:Animals; D001921:Brain / Q000201:enzymology*; D003994:Bucladesine / Q000494:pharmacology; D002461:Cell Line, Transformed; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000187:drug effects / Q000378:metabolism; D016207:Cytokines / Q000187:drug effects / Q000378:metabolism*; D004660:Encephalitis / Q000139:chemically induced / Q000201:enzymology* / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D005911:Gliosis / Q000139:chemically induced / Q000201:enzymology* / Q000503:physiopathology; D007378:Interleukins / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D017628:Microglia / Q000187:drug effects / Q000201:enzymology*; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000187:drug effects / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000187:drug effects / Q000378:metabolism
D016207:Cytokines; D004791:Enzyme Inhibitors; D007378:Interleukins; D008070:Lipopolysaccharides; D016328:NF-kappa B; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; D003994:Bucladesine; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases