title: The antimicrobial peptide, tilapia hepcidin 2-3, and PMA differentially regulate the protein kinase C isoforms, TNF-α and COX-2, in mouse RAW264.7 macrophages.
abstract: The antimicrobial and immunomodulatory functions of the antimicrobial peptide, tilapia hepcidin (TH)2-3, were previously studied. Herein, we report the differential modulation of protein kinase C (PKC)-associated proteins by TH2-3, and the PKC activator, phorbol 12-myristate 13-acetate (PMA), in RAW264.7 macrophages. Treatment with TH2-3 at 40 or 80μg/ml did not affect the cell morphology, but TH2-3 at 120μg/ml produced morphological changes similar to those after treatment with PMA in RAW264.7 cells. The coexistence of the PKC inhibitor, Ro-31-8220, prevented morphological changes induced by either PMA or 120μg/ml TH2-3 in RAW264.7 cells. Since PMA is known to induce expression of the proinflammatory cytokine, tumor necrosis factor (TNF)-α, activation of the TNF-α promoter in response to TH2-3 and PMA treatments in lipopolysaccharide (LPS)-stimulated cells was compared. In LPS-stimulated RAW264.7 cells, TNF-α promoter activity was significantly suppressed by TH2-3, but not by PMA. In addition, PMA activated prostaglandin synthase-associated cyclooxygenase (COX)-2 proteins on the cell surface, while the presence of TH2-3 inhibited its expression. Western blotting demonstrated that the expressions of PKC-μ, phosphorylated (p)-PKCμ at serine (S)-744, and p-PKCδ were activated by PMA, but were suppressed by TH2-3. In addition, p-PKC at S-916 was activated by TH2-3 and inhibited by PMA. In conclusion, the differential regulation of PKC isoforms by PMA and TH2-3 may influence morphological changes and regulation of TNF-α in RAW264.7 cells.
authors.affiliation: Marine Research Station, Institute of Cellular and Organismic Biology, Academia Sinica, Jiaushi, Ilan 262, Taiwan.
authors.forename: Venugopal
authors.initials: V
authors.lastname: Rajanbabu
authors.forename: Jyh-Yih
authors.initials: JY
authors.lastname: Chen
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D002460:Cell Line; D048430:Cell Shape / Q000187:drug effects; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D064451:Hepcidins; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D017210:Tilapia; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
chemical_list: D000943:Antigens, Differentiation; D023181:Antimicrobial Cationic Peptides; C579599:Hamp protein, mouse; D064451:Hepcidins; D007527:Isoenzymes; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate