Negative allosteric modulators that target human alpha4beta2 neuronal nicotinic receptors.
Allosteric modulation of neuronal nicotinic acetylcholine receptors (nAChRs) is considered to be one of the most promising approaches for therapeutics. We have previously reported on the pharmacological activity of several compounds that act as negative allosteric modulators (NAMs) of nAChRs. In the following studies, the effects of 30 NAMs from our small chemical library on both human alpha4beta2 (Halpha4beta2) and human alpha3beta4 (Halpha3beta4) nAChRs expressed in human embryonic kidney ts201 cells were investigated. During calcium accumulation assays, these NAMs inhibited nAChR activation with IC(50) values ranging from 2.4 microM to more than 100 microM. Several NAMs showed relative selectivity for Halpha4beta2 nAChRs with IC(50) values in the low micromolar range. A lead molecule, KAB-18, was identified that shows relative selectivity for Halpha4beta2 nAChRs. This molecule contains three phenyl rings, one piperidine ring, and one ester bond linkage. Structure-activity relationship (SAR) analyses of our data revealed three regions of KAB-18 that contribute to its relative selectivity. Predictive three-dimensional quantitative SAR (comparative molecular field analysis and comparative molecular similarity indices analysis) models were generated from these data, and a pharmacophore model was constructed to determine the chemical features that are important for biological activity. Using docking approaches and molecular dynamics on a Halpha4beta2 nAChR homology model, a binding mode for KAB-18 at the alpha/beta subunit interface that corresponds to the predicted pharmacophore is described. This binding mode was supported by mutagenesis studies. In summary, these studies highlight the importance of SAR, computational, and molecular biology approaches for the design and synthesis of potent and selective antagonists targeting specific nAChR subtypes.
Henderson
Brandon J
BJ
Division of Pharmacology, College of Pharmacy, Ohio State University, Columbus, Ohio 43210, USA.
Pavlovicz
Ryan E
RE
Allen
Jerad D
JD
González-Cestari
Tatiana F
TF
Orac
Crina M
CM
Bonnell
Andrew B
AB
Zhu
Michael X
MX
Boyd
R Thomas
RT
Li
Chenglong
C
Bergmeier
Stephen C
SC
McKay
Dennis B
DB
D000465:Algorithms; D001713:Biphenyl Compounds / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002460:Cell Line; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009474:Neurons / Q000187:drug effects*; D018722:Nicotinic Agonists / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D021281:Quantitative Structure-Activity Relationship; D011978:Receptors, Nicotinic / Q000187:drug effects* / Q000235:genetics; D013329:Structure-Activity Relationship
D001713:Biphenyl Compounds; D019086:Bridged Bicyclo Compounds, Heterocyclic; C579803:KAB-18; D018722:Nicotinic Agonists; D010880:Piperidines; D011725:Pyridines; D011978:Receptors, Nicotinic; C403531:nicotinic receptor alpha4beta2; C082748:epibatidine