Binding characteristics of [3H]-JSM10292: a new cell membrane-permeant non-peptide bradykinin B2 receptor antagonist.
OBJECTIVE
A (3) H-labelled derivative of the novel small-molecule bradykinin (BK) B(2) receptor antagonist JSM10292 was used to directly study its binding properties to human and animal B(2) receptors in intact cells and to closely define its binding site.


METHODS
Equilibrium binding, dissociation and competition studies with various B(2) receptor ligands and [(3) H]-JSM10292 were performed at 4°C and 37°C. The experiments were carried out using HEK293 cells stably (over)expressing wild-type and mutant B(2) receptors of human and animal origin.


RESULTS
[(3) H]-JSM10292 bound to B(2) receptors at 4°C and at 37°C with the same high affinity. Its dissociation strongly depended on the temperature and increased when unlabelled B(2) receptor agonists or antagonists were added. [(3) H]-JSM10292 is cell membrane-permeant and thus also bound to intracellular, active B(2) receptors, as indicated by the different 'nonspecific' binding in the presence of unlabelled JSM10292 or of membrane-impermeant BK. Equilibrium binding curves with [(3) H]-JSM10292 and competition experiments with unlabelled JSM10292 and [(3) H]-BK showed a different affinity profile for the wild-type B(2) receptor in different species (man, cynomolgus, rabbit, mouse, rat, dog, pig, guinea pig). Characterization of B(2) receptor mutants and species orthologues combined with homology modelling, using the CXCR4 as template, suggests that the binding site of JSM10292 is different from that of BK but overlaps with that of MEN16132, another small non-peptide B(2) receptor ligand.


CONCLUSIONS
[(3) H]-JSM10292 is a novel, cell membrane-permeant, high-affinity B(2) receptor antagonist that allows direct in detail studies of active, surface and intracellularly located wild-type and mutant B(2) receptors.
Institute for Cardiovascular Prevention, Ludwig-Maximilians-University, Pettenkoferstrasse 8a and 9, Munich, Germany. alexander.faussner@med.uni-muenchen.de
A
A
Faussner
S
S
Schüssler
J
J
Feierler
M
M
Bermudez
J
J
Pfeifer
K
K
Schnatbaum
T
T
Tradler
M
M
Jochum
G
G
Wolber
C
C
Gibson
D000818:Animals; D001667:Binding, Competitive; D001920:Bradykinin / Q000378:metabolism; D065094:Bradykinin B2 Receptor Antagonists; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability; D004285:Dogs; D006168:Guinea Pigs; D057809:HEK293 Cells; D006801:Humans; D008252:Macaca fascicularis; D051379:Mice; D009154:Mutation; D009952:Ornithine / Q000031:analogs & derivatives / Q000378:metabolism; D011728:Pyridones / Q000378:metabolism*; D011804:Quinolines / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D043782:Receptor, Bradykinin B2 / Q000235:genetics / Q000378:metabolism*; D013449:Sulfonamides / Q000378:metabolism; D013552:Swine
C506838:(4-amino-5-(4-(4-(2,4-dichloro-3-(2,4-dimethyl-8-quinolyloxymethyl)phenylsulfonamido)tetrahydro-2H-4-pyranoylcarbonyl)piperazino)-5-oxopentyl)(trimethyl)ammonium; C578193:1-(4-methyl-3-(2-methyl-4-(4-methyl-2H-pyrazol-3-yl)-quinolin-8-yloxymethyl)pyridin-2-ylmethyl)-3-trifluoromethyl-1H-pyridin-2-one; D065094:Bradykinin B2 Receptor Antagonists; D011728:Pyridones; D011804:Quinolines; D043782:Receptor, Bradykinin B2; D013449:Sulfonamides; D009952:Ornithine; D001920:Bradykinin