title: Identification of a crucial amino acid in the helix position 6.51 of human tachykinin neurokinin 1 and 3 receptors contributing to the insurmountable mode of antagonism by dual NK₁/NK₃ antagonists.
abstract: The neurokinins are neuropeptides that elicit their effect through three GPCRs called NK(1), NK(2), and NK(3). Compounds 5 and 6 are dual hNK(1) (K(i) of 0.7 and 0.3 nM) and hNK(3) (K(i) of 2.9 and 1.7 nM) antagonists. Both compounds exhibit an insurmountable mode of antagonism at hNK(1), whereas at hNK(3), they differ in that 5 is an insurmountable but 6 a surmountable antagonist. Using homology modeling and site-directed mutagenesis, hNK(1)-Phe264 and hNK(3)-Tyr315 were found to be the molecular determinants of hNK(1) and hNK(3) antagonism by 5 and 6. In [(3)H]IP studies, the mutation hNK(1)-F264Y converted the mode of action of 5 from insurmountable to partial insurmountable antagonism while it had no effect on that of 6. Conversely, the mutation hNK(3)-Y315F enhanced the insurmountable behavior of 5 and converted 6's surmountable to an insurmountable antagonism. This finding was further confirmed by characterizing additional derivatives of 5 and 6, most notably with a hybrid structure.
authors.affiliation: Medicinal Chemistry, Pharma Research and Early Development, F. Hoffmann-La Roche AG, Grenzacherstrasse 124, CH4070, Basel, Switzerland.
authors.forename: Caterina
authors.initials: C
authors.lastname: Bissantz
authors.forename: Claudia
authors.initials: C
authors.lastname: Bohnert
authors.forename: Torsten
authors.initials: T
authors.lastname: Hoffmann
authors.forename: Anne
authors.initials: A
authors.lastname: Marcuz
authors.forename: Patrick
authors.initials: P
authors.lastname: Schnider
authors.forename: Pari
authors.initials: P
authors.lastname: Malherbe
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D000631:Aminopyridines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D044482:Benzeneacetamides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D064729:Neurokinin-1 Receptor Antagonists; D017433:Protein Structure, Secondary; D011869:Radioligand Assay; D018040:Receptors, Neurokinin-1 / Q000737:chemistry / Q000235:genetics; D018042:Receptors, Neurokinin-3 / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics; D013237:Stereoisomerism
chemical_list: C558113:2-(3,5-bis-trifluoromethylphenyl)-N-(4-(4-fluoro-2-methylphenyl)-6-(3-hydroxy-2-hydroxymethylpyrrolidin-1-yl)pyridin-3-yl)-N-methylisobutyramide; D000596:Amino Acids; D000631:Aminopyridines; D044482:Benzeneacetamides; D007295:Inositol Phosphates; D064729:Neurokinin-1 Receptor Antagonists; D018040:Receptors, Neurokinin-1; D018042:Receptors, Neurokinin-3