Synergistic stimulation of interleukin 6 release and gene expression by phorbol esters and interleukin 1 beta in rat cortical astrocytes: role of protein kinase C activation and blockade.
The involvement of protein kinase C and its interaction with interleukin 1 beta in the control of interleukin 6 release by cortical astrocytes was studied. The blockade of protein kinase C catalytic domain, by staurosporine, as well as the desensitization of protein kinase C by short-term phorbol 12-myristate 13-acetate pretreatment, increased the basal release of interleukin 6 by rat cortical astrocytes, whereas calphostin C, an antagonist of phorbol ester binding on protein kinase C regulatory domain, did not affect the basal release of the cytokine. The activation of protein kinase C by phorbol 12-myristate 13-acetate enhanced concentration- and time-dependently interleukin 6 release. This stimulatory action of phorbol 12-myristate 13-acetate was significantly reduced by staurosporine, by calphostin C and by the desensitization of protein kinase C. Interleukin 1 beta increased interleukin 6 release in a concentration-related manner. Protein kinase C inhibition, by staurosporine or desensitization, potentiated severalfold, whereas calphostin C reduced interleukin 1 beta stimulation of interleukin 6 release. The treatment of cortical astrocytes with both interleukin 1 beta (3 ng/ml) and phorbol 12-myristate 13-acetate (10 nM) caused a synergistic stimulation of interleukin 6 release and its gene expression, an effect that was not relieved by either 20 nM staurospine or by calphostin C but was slightly affected by protein kinase C desensitization. In conclusion, our data show that in rat cortical astrocytes the basal release of interleukin 6 is under a tonic inhibition exerted by a protein kinase C isoform or isoforms sensitive to blockade by staurosporine and desensitization but insensitive to calphostin C.(ABSTRACT TRUNCATED AT 250 WORDS)
Grimaldi
M
M
Dipartimento di Neuroscienze e della Comunicazione Interumana, Università degli Studi di Napoli Federico II, Italy.
Arcone
R
R
Ciliberto
G
G
Schettini
G
G
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002540:Cerebral Cortex / Q000166:cytology; D004357:Drug Synergism; D004789:Enzyme Activation; D015870:Gene Expression / Q000187:drug effects*; D007375:Interleukin-1 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D007375:Interleukin-1; D015850:Interleukin-6; D012333:RNA, Messenger; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate