Serine phosphorylation of p60 tumor necrosis factor receptor by PKC-delta in TNF-alpha-activated neutrophils.
Tumor necrosis factor-alpha (TNF-alpha) triggers degranulation and oxygen radical release in adherent neutrophils. The p60TNF receptor (p60TNFR) is responsible for proinflammatory signaling, and protein kinase C (PKC) is a candidate for the regulation of p60TNFR. Both TNF-alpha and the PKC-activator phorbol 12-myristate 13-acetate triggered phosphorylation of p60TNFR. Receptor phosphorylation was on both serine and threonine but not on tyrosine residues. The PKC-delta isotype is a candidate enzyme for serine phosphorylation of p60TNFR. Staurosporine and the PKC-delta inhibitor rottlerin inhibited TNF-alpha-triggered serine but not threonine phosphorylation. Serine phosphorylation was associated with receptor desensitization, as inhibition of PKC resulted in enhanced degranulation (elastase release). After neutrophil activation, PKC-delta was the only PKC isotype that associated with p60TNFR within the correct time frame for receptor phosphorylation. In vitro, only PKC-delta, but not the alpha-, betaI-, betaII-, or zeta-isotypes, was competent to phosphorylate the receptor, indicating that p60TNFR is a direct substrate for PKC-delta. These findings suggest a selective role for PKC-delta in negative regulation of the p60TNFR and of TNF-alpha-induced signaling.
Kilpatrick
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Departments of Pediatrics and Biochemistry/Biophysics, University of Pennsylvania School of Medicine, and the Joseph Stokes Jr. Research Institute of the Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA. kilpatrick@email.chop.edu
Song
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Rossi
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Korchak
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D000098:Acetophenones / Q000494:pharmacology; D001578:Benzopyrans / Q000494:pharmacology; D015536:Down-Regulation / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018375:Neutrophil Activation / Q000187:drug effects / Q000276:immunology*; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology; D010196:Pancreatic Elastase / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051745:Protein Kinase C-delta; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D019311:Staurosporine / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D000098:Acetophenones; D001578:Benzopyrans; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D012694:Serine; C085746:rottlerin; C497258:PRKCD protein, human; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D010196:Pancreatic Elastase; D019311:Staurosporine