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Modes of inhibitory action of protein kinase C in the chemotactic peptide-induced formation of inositol phosphates in differentiated human leukemic (HL-60) cells.

1987; Elsevier BV; Volume: 262; Issue: 14 Linguagem: Inglês

10.1016/s0021-9258(18)48310-x

1083-351X

Akira Kikuchi, K. Ikeda, Osamu Kozawa, Yoshimi Takai,

Protein Tyrosine Phosphatases

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, Met-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 pretreated 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 GTPbinding protein leading to the formation of IP2.The reason for the failure of protein kinase C to inhibit the fMLP-induced formation of IPS in the cell-free membrane system is unknown, but several possible mechanisms are discussed.It is well established that the phospholipase C-mediated hydrolysis of phosphoinositides plays a role of crucial importance in transmembrane signaling (see for reviews, see Refs.1-4).In response to a wide variety of agonists, phosphoinositides including PI,' PIP, and PIPp, are hydrolyzed by the