title: Modes of inhibitory action of protein kinase C in the chemotactic peptide-induced formation of inositol phosphates in differentiated human leukemic (HL-60) cells.
abstract: Using the [3H]inositol-labeled plasma membranes isolated from the differentiated human leukemic (HL-60) cells, the mode of inhibitory action of the Ca2+/phospholipid-dependent enzyme protein kinase C in the chemotactic peptide, fMet-Leu-Phe (fMLP)-induced, phospholipase C-mediated hydrolysis of phosphoinositides was investigated. In this cell-free membrane system, fMLP in the presence of GTP plus Ca2+, GTP in the presence of Ca2+, or Ca2+ alone could induce the formation of inositol bis- and trisphosphate (IP2 and IP3, respectively). When the intact cells were pre-treated with 12-O-tetradecanoylphorbol-13-acetate, the fMLP- and GTP-induced formation of IP2 and IP3 was markedly reduced but the Ca2+-induced reactions were not reduced in the isolated membranes. This result suggests that protein kinase C impairs the coupling of the GTP-binding protein to the phospholipase C. In another experiment, preincubation of the isolated membranes with pure rat brain protein kinase C inhibited the fMLP-induced formation of IP2, but did not inhibit the GTP- or Ca2+-induced reaction. Under the same conditions, protein kinase C did not inhibit the fMLP-, GTP-, or Ca2+-induced formation of IP3. This result suggests that protein kinase C impairs additionally the coupling of the fMLP receptor to the GTP-binding protein leading to the formation of IP2. The reason for the failure of protein kinase C to inhibit the fMLP-induced formation of IP3 in the cell-free membrane system is unknown, but several possible mechanisms are discussed.
authors.forename: A
authors.initials: A
authors.lastname: Kikuchi
authors.forename: K
authors.initials: K
authors.lastname: Ikeda
authors.forename: O
authors.initials: O
authors.lastname: Kozawa
authors.forename: Y
authors.initials: Y
authors.lastname: Takai
mesh_terms: D019794:2,3-Diphosphoglycerate; D002118:Calcium / Q000494:pharmacology; D002454:Cell Differentiation; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004163:Diphosphoglyceric Acids / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006801:Humans; D007295:Inositol Phosphates / Q000096:biosynthesis*; D007700:Kinetics; D015470:Leukemia, Myeloid, Acute; D008563:Membrane Lipids / Q000096:biosynthesis; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*; D013403:Sugar Phosphates / Q000096:biosynthesis*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D004163:Diphosphoglyceric Acids; D007295:Inositol Phosphates; D008563:Membrane Lipids; D013403:Sugar Phosphates; D019794:2,3-Diphosphoglycerate; D009240:N-Formylmethionine Leucyl-Phenylalanine; D006160:Guanosine Triphosphate; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium