Regulation of AP-1 expression and activity in antigen-stimulated mast cells: the role played by protein kinase C and the possible involvement of Fos interacting protein.
We have recently observed that protein kinase C (PKC) was involved in the regulation of the accumulation of mRNAs of the AP-1 components in cultured Abelson-transformed murine fetal-liver-derived mast cells stimulated by exocytotic stimuli. Here we analyzed the probable regulatory effect of PKC on the synthesis and DNA-binding activity of AP-1 complexes in immunologic stimulated mast cells. In this study we used the interleukin-3--dependent murine fetal-liver--derived mast cells that were not transformed by the Abelson oncogene. Study of PKC-depleted cells showed PKC dependency of c-fos mRNA accumulation and protein expression in IgE-Ag stimulated cells. In contrast, the c-jun mRNA accumulation was unaffected by PKC depletion, whereas its protein expression was dependent on this enzymatic activity. This suggests the involvement of PKC in the regulation of translation of c-Jun, a level of c-Jun regulation that was not previously described. The amount of AP-1 DNA-bound complex was also lowered in PKC-depleted cells. Therefore, PKC plays an important regulatory role in different stages of the signal transduction pathway because of IgE-Ag stimulation. Surprisingly, we have observed that although the amount of total synthesized c-Fos began to increase 15 minutes after immunologic stimulation, the amount of c-Fos associated with Juns did not increase, even after 45 minutes. This association was not affected by PKC. Using a Fos-interacting protein (FIP)-cDNA probe, an expression of 2.9 kb mRNA was detected in these cells. Furthermore, immunologic stimulation caused an increase in the amount of a Fos-containing protein complex that bound to an FIP-binding DNA oligonucleotide. Therefore, we propose that this protein complex that contains most of the immunologically induced c-Fos has an important role in IgE-Ag-stimulated signal transduction.
Lewin
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Institute of Biochemistry, Hebrew University, Hadassah Medical School, Jerusalem, Israel.
Nechushtan
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Ke
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Razin
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E
D000818:Animals; D000941:Antigens / Q000494:pharmacology*; D001483:Base Sequence; D002460:Cell Line; D002474:Cell-Free System; D017931:DNA Primers; D015342:DNA Probes; D005089:Exocytosis; D005786:Gene Expression Regulation; D016762:Genes, fos / Q000187:drug effects; D016758:Genes, jun / Q000187:drug effects; D007073:Immunoglobulin E / Q000494:pharmacology; D008407:Mast Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011493:Protein Kinase C / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D000941:Antigens; D017931:DNA Primers; D015342:DNA Probes; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D007073:Immunoglobulin E; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate