title: Inhibition of the human P2X7 receptor by a novel protein tyrosine kinase antagonist.
abstract: A panel of 18 protein tyrosine kinase antagonists were tested for their inhibitory effect on human P2X(7) receptor-mediated (86)Rb(+) (K(+)) efflux. The most potent compound (compound P), a phthalazinamine derivative and an inhibitor of vascular endothelial growth factor receptor kinase, blocked ATP-induced (86)Rb(+)-efflux in human B-lymphocytes and erythrocytes by 76% and 66%, respectively. This inhibition was dose-dependent in both cell types with an IC(50) of approximately 5muM. Kinetic analysis showed compound P was a non-competitive inhibitor of P2X(7). This compound also inhibited ATP-induced ethidium(+) influx into B-lymphocytes and P2X(7)-transfected-HEK-293 cells, as well as ATP-induced (86)Rb(+)-efflux from canine erythrocytes. Externally, but not internally, applied compound P impaired ATP-induced inward currents in P2X(7)-transfected-HEK-293 cells. This study demonstrates that a novel protein tyrosine kinase antagonist directly impairs native and recombinant human P2X(7) receptors. The data suggests that antagonists which target ATP-binding sites of kinases may potentially block the P2X(7) receptor.
authors.affiliation: Department of Medicine, Nepean Clinical School, University of Sydney, Penrith, NSW, Australia.
authors.forename: Anne N
authors.initials: AN
authors.lastname: Shemon
authors.forename: Ronald
authors.initials: R
authors.lastname: Sluyter
authors.forename: Leanne
authors.initials: L
authors.lastname: Stokes
authors.forename: Paul W
authors.initials: PW
authors.lastname: Manley
authors.forename: James S
authors.initials: JS
authors.lastname: Wiley
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000814:Aniline Compounds / Q000737:chemistry* / Q000494:pharmacology; D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D004285:Dogs; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism; D004996:Ethidium / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D010793:Phthalazines / Q000737:chemistry* / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D058919:Purinergic P2 Receptor Antagonists; D058486:Receptors, Purinergic P2X7; D012414:Rubidium Radioisotopes / Q000378:metabolism
chemical_list: D000814:Aniline Compounds; C525867:N-(4-(1-methylethyl)phenyl)-4-(2-(3-pyridinyl)ethyl)-1-phthalazinamine; C546468:P2RX7 protein, human; D010793:Phthalazines; D047428:Protein Kinase Inhibitors; D058919:Purinergic P2 Receptor Antagonists; D058486:Receptors, Purinergic P2X7; D012414:Rubidium Radioisotopes; D000255:Adenosine Triphosphate; D011505:Protein-Tyrosine Kinases; D004996:Ethidium; D011188:Potassium