Interleukin-1 beta induction of TNF-alpha gene expression: involvement of protein kinase C.
In the human astroglioma cell line CH235-MG, interleukin-1 beta (IL-1 beta) induces transcriptional activation of the tumor necrosis factor-alpha (TNF-alpha) gene, resulting in expression of TNF-alpha mRNA and biologically active TNF-alpha protein. This study was undertaken to elucidate intracellular signaling pathways involved in IL-1 beta induction of the TNF-alpha gene. We demonstrated that the protein kinase C (PKC) activator 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) in concert with Ca++ ionophore A23187 induced expression of TNF-alpha mRNA and protein, whereas an inactive PMA analogue (alpha PMA) had no effect. Various cyclic nucleotide activators such as 8-Bromo cAMP, cholera toxin, and forskolin had no effect on TNF-alpha production. Two PKC inhibitors, H7 and staurosporine (SS), abrogated IL-1 beta induced TNF-alpha expression in a dose-dependent fashion. Treatment of CH235-MG cells with a high concentration of PMA (1 microM) for an extended period of time (48 h) caused a greater than 90% reduction in total PKC activity. Further strengthening a role for PKC in this cytokine response is the fact that IL-1 beta was no longer able to induce TNF-alpha expression in these PKC depleted cells. Last, IL-1 beta treatment produced an increase of total PKC activity in CH235-MG cells. Taken together, these data demonstrate that IL-1 beta induces TNF-alpha gene expression in CH235-MG cells in a PKC-dependent manner.
Bethea
J R
JR
Department of Cell Biology, University of Alabama, Birmingham 35294.
Gillespie
G Y
GY
Benveniste
E N
EN
D004789:Enzyme Activation; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism
D007375:Interleukin-1; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D011493:Protein Kinase C