Desensitization by protein kinase C activation differentially uncouples formyl peptide receptors from effector enzymes in HL-60 granulocytes.
The hypothesis that protein kinase C (PKC) participates in agonist-mediated desensitization of formyl peptide receptors in HL-60 granulocytes was tested. fMet-Leu-Phe and leukotriene B4(LTB4) produced homologous desensitization of agonist-stimulated intracellular calcium transients. Pre-treatment with the PKC activator, phorbol myristate acetate (PMA; 10 nM), abolished both fMet-Leu-Phe and LTB4-stimulated calcium transients. Membranes prepared from control HL-60 granulocytes (NM) or cells treated with 10 nM PMA (PMA-M) demonstrated increased formyl peptide receptor and G protein density, as determined by radioligand binding and pertussis toxin- and cholera toxin-catalysed ADP ribosylation. fMet-Leu-Phe stimulation of guanosine 5'-[gamma-thio]-triphosphate (GTP gamma S) binding and GTP hydrolysis and GDP inhibition of fMet-Leu-Phe binding were not different between NM and PMA-M. Pre-treatment with 10 nM PMA did not inhibit subsequent fMet-Leu-Phe-stimulated superoxide generation or phospholipase D activation. We conclude that PKC desensitizes fMet-Leu-Phe-stimulated phospholipase C, but not phospholipase D, responses and that PKC activation does not mediate agonist-induced desensitization of formyl peptide receptors.
Lederer
E D
ED
Department of Medicine, University of Louisville, KY 40292.
Jacobs
A A
AA
McLeish
K R
KR
D001345:Autoradiography; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D004789:Enzyme Activation / Q000502:physiology; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006098:Granulocytes / Q000378:metabolism; D007975:Leukotriene B4 / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000031:analogs & derivatives / Q000494:pharmacology; D010739:Phospholipase D / Q000502:physiology*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000378:metabolism*; D018000:Receptors, Peptide / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D008565:Membrane Proteins; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D018000:Receptors, Peptide; D007975:Leukotriene B4; D009240:N-Formylmethionine Leucyl-Phenylalanine; C042205:methionyl-leucyl-phenylalanine; D011493:Protein Kinase C; D010739:Phospholipase D; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium