The Novel Î±7Î²2-Nicotinic Acetylcholine Receptor Subtype Is Expressed In Mouse And Human Basal Forebrain: Biochemical And Pharmacological Characterization
We examined Î±7Î²2-nicotinic acetylcholine receptor (Î±7Î²2-nAChR) expression in mammalian brain and compared pharmacological profiles of homomeric Î±7- nAChRs and Î±7Î²2-nAChRs. Î±-Bungarotoxin affinity purification or immunoprecipitation with anti-Î±7 subunit antibodies (Abs) was used to isolate nAChRs containing Î±7 subunits from mouse or human brain samples. Î±7Î²2-nAChRs were detected in forebrain, but not other tested regions, from both species, based on Western blot analysis of isolates using Î²2 subunit-specific Abs. Ab specificity was confirmed in control studies using subunit-null mutant mice or cell lines heterologously expressing specific human nAChR subtypes and subunits. Functional expression in Xenopus oocytes of concatenated pentameric (Î±7) 5-, (Î±7)4(Î²2) 1-, and (Î±7)3(Î²2) 2-nAChRs was confirmed using two-electrode voltage clamp recording of responses to nicotinic ligands. Importantly, pharmacological profiles were indistinguishable for concatenated (Î±7)5-nAChRs or for homomeric Î±7-nAChRs constituted from unlinked Î±7 subunits. Pharmacological profiles were similar for (Î±7)5-, (Î±7)4(Î² 2)1-, and (Î±7) 3(Î²2)2-nAChRs except for diminished efficacy of nicotine (normalized to acetylcholine efficacy) at Î±7Î²2- versus Î±7-nAChRs. This study represents the first direct confirmation of Î±7Î² 2-nAChR expression in human and mouse forebrain, supporting previous mouse studies that suggested relevance of Î±7Î²2- nAChRs in Alzheimer disease etiopathogenesis. These data also indicate that Î±7Î²2-nAChR subunit isoforms with different Î±7/Î²2 subunit ratios have similar pharmacological profiles to each other and to Î±7 homopentameric nAChRs. This supports the hypothesis that Î±7Î² 2-nAChR agonist activation predominantly or entirely reflects binding to Î±7/Î±7 subunit interface sites. Copyright Â© 2014 by The American Society for Pharmacology and Experimental Therapeutics.
Digital Object Identifier (DOI)
Moretti, Milena; Zoli, Michele; George, Andrew A.; Lukas, Ronald J.; Pistillo, Francesco; Maskos, Uwe; Whiteaker, Paul; and Gotti, Cecilia, "The Novel Î±7Î²2-Nicotinic Acetylcholine Receptor Subtype Is Expressed In Mouse And Human Basal Forebrain: Biochemical And Pharmacological Characterization" (2014). Neurobiology. 283.