title: Substituted 2-Aminopyrimidines Selective for α7-Nicotinic Acetylcholine Receptor Activation and Association with Acetylcholine Binding Proteins.
abstract: Through studies with ligand binding to the acetylcholine binding protein (AChBP), we previously identified a series of 4,6-substituted 2-aminopyrimidines that associate with this soluble surrogate of the nicotinic acetylcholine receptor (nAChR) in a cooperative fashion, not seen for classical nicotinic agonists and antagonists. To examine receptor interactions of this structural family on ligand-gated ion channels, we employed HEK cells transfected with cDNAs encoding three requisite receptor subtypes: α7-nAChR, α4β2-nAChR, and a serotonin receptor (5-HT3AR), along with a fluorescent reporter. Initial screening of a series of over 50 newly characterized 2-aminopyrimidines with affinity for AChBP showed only two to be agonists on the α7-nAChR below 10 μM concentration. Their unique structural features were incorporated into design of a second subset of 2-aminopyrimidines yielding several congeners that elicited α7 activation with EC50values of 70 nM and Kdvalues for AChBP in a similar range. Several compounds within this series exhibit specificity for the α7-nAChR, showing no activation or antagonism of α4β2-nAChR or 5-HT3AR at concentrations up to 10 μM, while others were weaker antagonists (or partial agonists) on these receptors. Analysis following cocrystallization of four ligand complexes with AChBP show binding at the subunit interface, but with an orientation or binding pose that differs from classical nicotinic agonists and antagonists and from the previously analyzed set of 2-aminopyrimidines that displayed distinct cooperative interactions with AChBP. Orientations of aromatic side chains of these complexes are distinctive, suggesting new modes of binding at the agonist-antagonist site and perhaps an allosteric action for heteromeric nAChRs.
authors.affiliation: Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego , La Jolla, California 92093-0650, United States.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kaczanowska
authors.affiliation: Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego , La Jolla, California 92093-0650, United States.|Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California , Calzada Universidad 14418, Tijuana, Baja California 22390, Mexico.
authors.forename: Gisela Andrea
authors.initials: GA
authors.lastname: Camacho Hernandez
authors.affiliation: Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego , La Jolla, California 92093-0650, United States.
authors.forename: Larissa
authors.initials: L
authors.lastname: Bendiks
authors.affiliation: Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego , La Jolla, California 92093-0650, United States.
authors.forename: Larissa
authors.initials: L
authors.lastname: Kohs
authors.affiliation: Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California , Calzada Universidad 14418, Tijuana, Baja California 22390, Mexico.
authors.forename: Jose Manuel
authors.initials: JM
authors.lastname: Cornejo-Bravo
authors.affiliation: Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego , La Jolla, California 92093-0650, United States.
authors.forename: Michal
authors.initials: M
authors.lastname: Harel
authors.affiliation: School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: M G
authors.identifier: 0000-0001-8247-3108
authors.initials: MG
authors.lastname: Finn
authors.affiliation: Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego , La Jolla, California 92093-0650, United States.
authors.forename: Palmer
authors.identifier: 0000-0002-3081-131X
authors.initials: P
authors.lastname: Taylor
mesh_terms: D000109:Acetylcholine / Q000737:chemistry / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D018360:Crystallography, X-Ray; D057809:HEK293 Cells; D006801:Humans; D008958:Models, Molecular; D015394:Molecular Structure; D011743:Pyrimidines / Q000737:chemistry / Q000378:metabolism*; D064569:alpha7 Nicotinic Acetylcholine Receptor / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D011743:Pyrimidines; D064569:alpha7 Nicotinic Acetylcholine Receptor; C012180:2-aminopyrimidine; D000109:Acetylcholine