Stimulation of interleukin-6 promoter by parathyroid hormone, tumor necrosis factor alpha, and interleukin-1beta in UMR-106 osteoblastic cells is inhibited by protein kinase C antagonists.
To investigate the level at which protein kinase C (PKC) regulates expression of interleukin-6 (IL-6) in osteoblastic cells, effects of several PKC antagonists and PKC down-regulation by phorbol ester were studied in UMR-106 osteoblastic cells that had been transiently transfected with a -224/+11-base pair (bp) IL-6 promoter coupled to a luciferase reporter. Parathyroid hormone (PTH) elicited a dose-dependent stimulation of the IL-6 promoter expression, with significant increases produced by 5 h of treatment with concentrations of PTH as low as 10(-14) M. The increase in IL-6 promoter expression was inhibited by the PKC antagonists GF109203X, 30 nM to 1 microM, and calphostin C, 250 nM. Prior down-regulation of PKC with 100 nM phorbol-12,13-dibutyrate (PDBU) for 48 h inhibited the PTH effect as well as the smaller stimulatory effects elicited by tumor necrosis factor alpha (TNF-alpha), 10(-9)-10(-8) M, and by IL-1beta, 1-10 ng/ml. In contrast to these findings, the stimulatory effects of PTH, TNF-alpha, and IL-1beta on the IL-6 promoter expression were enhanced by staurosporine. Treatment with GF109203X or down-regulation of PKC with PDBU prevented the stimulatory effects of staurosporine. PKC activity was increased by staurosporine. The findings with staurosporine are consistent with our earlier observations that this agent enhances the calcium signaling and bone resorption elicited by PTH. The studies support the role of PKC in the stimulatory effects of PTH, TNF-alpha, and IL-1beta on IL-6 expression.
Nagy
Z
Z
Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60611, USA.
Radeff
J
J
Stern
P H
PH
D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007375:Interleukin-1 / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics*; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008301:Maleimides / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D010281:Parathyroid Hormone / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D019311:Staurosporine / Q000494:pharmacology; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000494:pharmacology
D004791:Enzyme Inhibitors; D007211:Indoles; D007375:Interleukin-1; D015850:Interleukin-6; D008301:Maleimides; D009281:Naphthalenes; D010281:Parathyroid Hormone; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C061465:calphostin complex; D015240:Phorbol 12,13-Dibutyrate; D008156:Luciferases; D011493:Protein Kinase C; D019311:Staurosporine; C070515:bisindolylmaleimide I