Inhibitory effects of GMCHA-OPhBut on phospholipid methylation and histamine release in mast cells activated by concanavalin A, anti-IgE, and antigen.
[3H]Methyl group incorporation and histamine secretion in rat mast cells induced by anti-IgE and con A were strongly inhibited by trans-4-guanidinomethylcyclohexanecarboxylic acid 4-tert-butylphenyl ester (GMCHA-OPhBut), a strong and specific inhibitor for pH 7 tryptase (Muramatsu et al. (1988) Biol. Chem. Hoppe-Seyler 369, 617-625) which is present in rat mast cells. The IC50s for these events were of the order of 10(-6) M. Addition of GMCHA-OPhBut after the maximal increase in [3H]methyl group incorporation in rat mast cells activated by con A and anti-IgE induced rapid reduction of the methylated phospholipid, and the later histamine release was strongly suppressed. Mast cells were prepared with Mg2+-free Tyrode-HEPES solution, and challenged with anti-IgE with or without Mg2+. With Mg2+, [3H]methyl group incorporation was enhanced, and histamine was secreted time-dependently. Without Mg2+, [3H]methyl group incorporation fell to one-third, whereas histamine secretion was not affected. These results were incompatible with the above results. From these results it was strongly suggested that a trypsin-like protease, probably pH 7 tryptase, is involved not only in the early events, such as activation of phosphatidylethanolamine methyltransferase I and/or II, but also in the late events such as histamine release, and phospholipid methylation is not associated with histamine secretion.
Takei
M
M
Faculty of Pharmacy, Tokushima Bunri University.
Matumoto
T
T
Endo
K
K
Muramatu
M
M
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D000941:Antigens / Q000276:immunology; D003208:Concanavalin A / Q000494:pharmacology; D003509:Cyclohexanecarboxylic Acids / Q000494:pharmacology*; D006636:Histamine Release / Q000187:drug effects*; D007073:Immunoglobulin E / Q000276:immunology; D008297:Male; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism*; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism; D010567:Pertussis Vaccine / Q000276:immunology; D050941:Phosphatidyl-N-Methylethanolamine N-Methyltransferase; D050918:Phosphatidylethanolamine N-Methyltransferase; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000888:Antibodies, Anti-Idiotypic; D000941:Antigens; D003509:Cyclohexanecarboxylic Acids; D010567:Pertussis Vaccine; D010743:Phospholipids; C026408:anti-IgE antibodies; D003208:Concanavalin A; D007073:Immunoglobulin E; C038303:NCO 650; D008780:Methyltransferases; D050918:Phosphatidylethanolamine N-Methyltransferase; D050941:Phosphatidyl-N-Methylethanolamine N-Methyltransferase