Protein kinase C regulates proliferation of mast cells and the expression of the mRNAs of fos and jun proto-oncogenes during activation by IgE-Ag or calcium ionophore A23187.
Short-term stimulation (up to 16 hours) of interleukin-3 (IL-3)-dependent mouse bone marrow-derived mast cells, Abelson transformed mouse liver-derived mast cells, or rat basophilic leukemia cells by either IgE-Ag or calcium ionophore A23187 resulted in inhibition of their proliferation as measured by 3H-thymidine incorporation and MTT (tetrazolium) assays, and in accumulation of the mRNAs of c-fos, c-jun, junB and slightly of junD proto-oncogenes. The involvement of protein kinase C (PKC) in these responses was investigated by using several approaches of enzyme activity regulation. Direct activation of the PKC was achieved by short-term exposure of the cells to the PKC-specific activator phorbol 12-myristate-13-acetate (PMA). Inhibition of PKC activity was obtained by either prolonged treatment of the cells with PMA or by exposure of the cells to the PKC inhibitors H-7 and staurosporine. The results showed the following: (1) Short-term exposure of mast cells to PMA was sufficient to induce inhibition of proliferation. (2) An increase in PKC activity was associated with a decrease in the proliferation of IgE-dinitrophenol (DNP) or calcium ionophore A23187-stimulated cells. (3) A direct correlation was found between the increase in PKC activity and the increase in the level of the mRNAs of the jun proto-oncogenes in cells activated by both stimuli mentioned. (4) While an increase in PKC activity was associated with the upregulation of the level of c-fos mRNA during calcium ionophore A23187 stimulation, it showed the opposite effect on the expression of the mRNA of this proto-oncogene when the cells were triggered by IgE-DNP. Therefore, we concluded that PKC plays various roles in the expression of the mRNA of c-fos in activated mast cells depending on the stimulus involved. In addition, the expression of the mRNA of c-jun and junB proto-onogenes is not coordinately regulated with that of c-fos during immunologic stimulation. This discordancy, which is associated with the increase in PKC activity in mast cells, may play a role in the regulation of the transcription of AP-1-responsive genes, and therefore could be associated with the regulation of proliferation of these cells.
Baranes
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D
Institute of Biochemistry, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Razin
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E
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002455:Cell Division; D002461:Cell Line, Transformed; D004140:Dinitrophenols / Q000276:immunology; D005786:Gene Expression Regulation; D016762:Genes, fos / Q000235:genetics*; D016758:Genes, jun / Q000235:genetics*; D007073:Immunoglobulin E / Q000276:immunology; D015471:Leukemia, Basophilic, Acute; D008099:Liver / Q000166:cytology; D008407:Mast Cells / Q000166:cytology* / Q000187:drug effects / Q000276:immunology; D051379:Mice; D011493:Protein Kinase C / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D012710:Serum Albumin, Bovine / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D004140:Dinitrophenols; D012333:RNA, Messenger; C034638:dinitrophenyl-bovine serum albumin; D012710:Serum Albumin, Bovine; D007073:Immunoglobulin E; D000001:Calcimycin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate