Repression of proinflammatory cytokine and inducible nitric oxide synthase(NOS2) gene expression in activated microglia by N-Acetyl-O-methyldopamine: Protein kinase A - Dependent mechanism

Citation
S. Cho et al., Repression of proinflammatory cytokine and inducible nitric oxide synthase(NOS2) gene expression in activated microglia by N-Acetyl-O-methyldopamine: Protein kinase A - Dependent mechanism, GLIA, 33(4), 2001, pp. 324-333
Citations number
68
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences & Behavoir
Journal title
GLIA
ISSN journal
0894-1491 → ACNP
Volume
33
Issue
4
Year of publication
2001
Pages
324 - 333
Database
ISI
SICI code
0894-1491(20010315)33:4<324:ROPCAI>2.0.ZU;2-Z
Abstract
Excessive proinflammatory cytokine and NO production by activated microglia play a role in neurodegenerative disorders. To investigate whether the neu roprotectant N-acetyl-O-methyldopamine (NAMDA) downregulates genes associat ed with microglial activation, we measured gene expression of TNF-alpha, IL -1 beta, inducible nitric oxide synthase (NOS2), and an associated cofactor synthesis gene, GTP cyclohydrolase I(GTPCH) in LPS-stimulated microglia ce lls in the presence or absence of NAMDA. The temporal pattern of cytokine g ene expression showed that LPS (0.2 mug/ml) increased TNF-alpha and IL-1 be ta gene expression at 1 and 3 h, which was repressed by cotreatment of NAMD A. Similarly, LPS also induced GTPCH and NOS2 gene expression at 3 and 6 h, and cotreatment of NAMDA repressed the induction with parallel reduction o f nitrite, an oxidative metabolite of nitric oxide. Since transcription fac tor NF-kappaB is involved in regulating expression of these genes, the effe cts of NAMDA on NF-kappaB nuclear translocation and DNA binding in immunost imulated microglia were investigated. We found that neither LPS-induced NF- kappaB translocation nor DNA binding activity was affected by cotreatment w ith NAMDA in BV-2 microglia. On the other hand, NAMDA increased intracellul ar cAMP levels and potentiated LPS-induced phosphorylated cAMP-responsive e lement binding protein (pCREB) expression. Treatment with adenosine 3 '5 ' -cyclic monophosphothioate, a specific inhibitor of cAMP-dependent protein kinase (PKA), reversed not only NAMDA-induced pCREB upregulation but also N AMDA-induced repression of TNF-alpha and IL-1 beta gene transcription. The data demonstrate that NAMDA represses LPS-induced proinflammatory cytokines gene expression via a cAMP-dependent protein kinase pathway. Thus, repress ing proinflammatory cytokines and NOS2 gene expression in activated microgl ia by NAMDA may provide new therapeutic strategies for ischemic cerebral di sease as well as other neurodegenerative diseases. GLIA 33:324-333, 2001. ( C) 2001 Wiley-Liss, Inc.