title: ER-27319, an acridone-related compound, inhibits release of antigen-induced allergic mediators from mast cells by selective inhibition of fcepsilon receptor I-mediated activation of Syk.
abstract: Engagement of the mast cell high-affinity receptor for immunoglobulin E (IgE), FcepsilonRI, induces tyrosine phosphorylation of Syk, a non-receptor tyrosine kinase, that has been demonstrated as critical for degranulation. Herein we describe a synthetic compound, ER-27319, as a potent and selective inhibitor of antigen or anti-IgE-mediated degranulation of rodent and human mast cells. ER-27319 affected neither Lyn kinase activity nor the antigen-induced phosphorylation of the FcepsilonRI but did effectively inhibit the tyrosine phosphorylation of Syk and thus its activity. As a consequence, tyrosine phosphorylation of phospholipase C-gamma1, generation of inositol phosphates, release of arachidonic acid, and secretion of histamine and tumor necrosis factor alpha were also inhibited. ER-27319 did not inhibit the anti-CD3-induced tyrosine phosphorylation of phospholipase C-gamma1 in Jurkat T cells, demonstrating a specificity for Syk-induced signals. In contrast the tyrosine phosphorylation and activation of Syk, induced by in vitro incubation with the phosphorylated immunoreceptor tyrosine-based activation motif (ITAM) of FcepsilonRI gamma subunit or by antigen activation of RBL-2H3 cells, was specifically inhibited by ER-27319. However, when ER-27319 was added to immunoprecipitated Syk, derived from activated cells, no effect was seen on Syk activity. ER-27319 did not inhibit the tyrosine phosphorylation of Syk induced by activation in the presence of Igbeta ITAM or the anti-IgM-induced phosphorylation of Syk in human peripheral B cells. Therefore, ER-27319 selectively interferes with the FcepsilonRI gamma phospho-ITAM activation of Syk in vitro and in intact cells. These results confirm the importance of Syk in FcepsilonRI-mediated responses in mast cells and demonstrate the mast cell selectivity and therapeutic potential of ER-27319 in the treatment of allergic disease.
authors.affiliation: Department of Drug Discovery, Tsukuba Research Laboratories, Eisai Company, Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 30026, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Moriya
authors.forename: J
authors.initials: J
authors.lastname: Rivera
authors.forename: S
authors.initials: S
authors.lastname: Odom
authors.forename: Y
authors.initials: Y
authors.lastname: Sakuma
authors.forename: K
authors.initials: K
authors.lastname: Muramato
authors.forename: T
authors.initials: T
authors.lastname: Yoshiuchi
authors.forename: M
authors.initials: M
authors.lastname: Miyamoto
authors.forename: K
authors.initials: K
authors.lastname: Yamada
mesh_terms: D000166:Acridines / Q000737:chemistry / Q000494:pharmacology*; D000485:Allergens / Q000276:immunology / Q000494:pharmacology; D000818:Animals; D015550:Cell Degranulation / Q000187:drug effects*; D002460:Cell Line; D004792:Enzyme Precursors / Q000276:immunology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008407:Mast Cells / Q000276:immunology*; D011505:Protein-Tyrosine Kinases / Q000276:immunology*; D017455:Receptors, IgE / Q000276:immunology*; D015398:Signal Transduction / Q000187:drug effects* / Q000276:immunology; D000072377:Syk Kinase
chemical_list: D000166:Acridines; D000485:Allergens; D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D017455:Receptors, IgE; C109226:ER 27319; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase