Article

Induction of COX-2 and PGE(2) biosynthesis by IL-1beta is mediated by PKC and mitogen-activated protein kinases in murine astrocytes.

Neural Plasticity Department, Instituto Cajal, Consejo Superior de Investigaciones Cientificas, Avda. Dr. Arce 37, 28002 Madrid, Spain.
British Journal of Pharmacology (impact factor: 4.41). 10/2000; 131(1):152-9. DOI:10.1038/sj.bjp.0703557
Source: PubMed

ABSTRACT Interleukin-1 (IL-1) is an important mediator of immunoinflammatory responses in the brain. In the present study, we examined whether prostaglandin E(2) (PGE(2)) production after IL-1beta stimulation is dependent upon activation of protein kinases in astroglial cells. Astrocyte cultures stimulated with IL-1beta or the phorbol ester, PMA significantly increased PGE(2) secretion. The stimulatory action of IL-1beta on PGE(2) production was totally abolished by NS-398, a specific inhibitor of cyclo-oxygenase-2 activity, as well as by the protein synthesis inhibitor cycloheximide, and the glucocorticoid dexamethasone. Furthermore, IL-1beta induced the expression of COX-2 mRNA. This occurred early at 2 h, with a maximum at 4 h and declined at 12 h. IL-1 beta treatment also induced the expression of COX-2 protein as determined by immunoblot analysis. In that case the expression of the protein remained high at least up to 12 h. Treatment of cells with protein kinase C inhibitors (H-7, bisindolylmaleimide and calphostin C) inhibited IL-1beta stimulation of PGE(2). In addition, PKC-depleted astrocyte cultures by overnight treatment with PMA no longer responded to PMA or IL-1. The ablation of the effects of PMA and IL-1beta on PGE(2) production, likely results from down-regulation of phorbol ester sensitive-PKC isoenzymes. Immunoblot analysis demonstrated the translocation of the conventional isoform cPKC-alpha from cytosol to membrane following treatment with IL-1beta. In addition, IL-1beta treatment led to activation of extracellular signal-regulated kinase (ERK1/2) and p38 subgroups of MAP kinases in astroglial cells. Interestingly, the inhibition of ERK kinase with PD 98059, as well as the inhibition of p38 MAPK with SB 203580, prevented IL-1beta-induced PGE(2) release. ERK1/2 activation by IL-1beta was sensitive to inhibition by the PKC inhibitor bisindolylmaleimide suggesting that ERK phosphorylation is a downstream signal of PKC activation. These results suggest key roles for PKC as well as for ERK1/2 and p38 MAP kinase cascades in the biosynthesis of PGE(2), likely by regulating the induction of cyclo-oxygenase-2, in IL-1beta-stimulated astroglial cells.

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Keywords

12 h. IL-1 beta treatment
 
12 h. Treatment
 
Astrocyte cultures
 
calphostin C
 
COX-2 protein
 
cyclo-oxygenase-2 activity
 
ERK kinase
 
ERK1/2 activation
 
extracellular signal-regulated kinase
 
IL-1beta stimulation
 
IL-1beta treatment
 
IL-1beta-stimulated astroglial cells
 
immunoinflammatory responses
 
p38 MAP kinase cascades
 
PKC activation
 
PKC inhibitor bisindolylmaleimide
 
PKC-depleted astrocyte cultures
 
protein synthesis inhibitor cycloheximide
 
specific inhibitor
 
stimulatory action