title: Functional and structural interaction of (-)-lobeline with human α4β2 and α4β4 nicotinic acetylcholine receptor subtypes.
abstract: To determine the pharmacologic activity of (-)-lobeline between human (h)α4β2 and hα4β4 nicotinic acetylcholine receptors (AChRs), functional and structural experiments were performed. The Ca(2+) influx results established that (-)-lobeline neither actives nor enhances the function of the studied AChR subtypes, but competitively inhibits hα4β4 AChRs with potency ∼10-fold higher than that for hα4β2 AChRs. This difference is due to a higher binding affinity for the [(3)H]cytisine sites at hα4β4 compared to hα4β2 AChRs, which, in turn, can be explained by our molecular dynamics (MD) results: (1) higher stability of (-)-lobeline and its hydrogen bonds within the α4β4 pocket compared to the α4β2 pocket, (2) (-)-lobeline promotes Loop C to cap the binding site at the α4β4 pocket, but forces Loop C to get apart from the α4β2 pocket, precluding the gating process elicited by agonists, and (3) the orientation of (-)-lobeline within the α4β4, but not the α4β2, subpocket, promoted by the t- (or t+) rotameric state of α4-Tyr98, remains unchanged during the whole MD simulation. This study gives a detailed view of the molecular and dynamics events evoked by (-)-lobeline supporting the differential binding affinity and subsequent inhibitory potency between hα4β2 and hα4β4 AChRs, and supports the possibility that the latter subtype is also involved in its activity.
authors: Department of Medical Education, California Northstate University College of Medicine, Elk Grove, CA, USA. Electronic address: hugo.arias@cnsu.edu.
authors: Hugo R
authors: HR
authors: Arias
authors: Neuroscience Research, Novartis Institutes for Biomedical Research, Basel, Switzerland.
authors: Dominik
authors: D
authors: Feuerbach
authors: Faculty of Medicine and CONICET, University of Morón, Argentina.
authors: Marcelo
authors: M
authors: Ortells
mesh_terms: D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D020013:Calcium Signaling; D006224:Cricetinae; D003412:Cricetulus; D057809:HEK293 Cells; D006801:Humans; D006860:Hydrogen Bonding; D020128:Inhibitory Concentration 50; D008120:Lobeline / Q000737:chemistry / Q000494:pharmacology*; D056004:Molecular Dynamics Simulation; D018722:Nicotinic Agonists / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011978:Receptors, Nicotinic / Q000737:chemistry / Q000378:metabolism*
chemical_list: D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; C427403:alpha(4)beta(4) nicotinic receptor; C403531:nicotinic receptor alpha4beta2; D008120:Lobeline
keywords: (−)-Lobeline; Ca(2+) influx; Competitive antagonist; Human α4β2 and α4β4 nicotinic acetylcholine receptors; Molecular modeling