Desformylflustrabromine Modulates alpha4beta2 Neuronal Nicotinic Acetylcholine Receptor High- and Low-Sensitivity Isoforms at Allosteric Clefts Containing the beta2 Subunit

Author: Weltzin, M.M.; Schulte, M.K.

Description: Alterations in expression patterns of alpha4beta2 nicotinic acetylcholine receptors have been demonstrated to alter cholinergic neurotransmission and are implicated in neurologic disorders, including autism, nicotine addiction, Alzheimer’s disease, and Parkinson’s disease. Positive allosteric modulators (PAMs) represent promising new leads in the development of therapeutic agents for the treatment of these disorders. This study investigates the involvement of the beta2-containing subunit interfaces of alpha4beta2 receptors in the modulation of acetylcholine (ACh)-induced responses by the PAM desformylflustrabromine (dFBr). Eight amino acids on the principal face of the beta2 subunit were mutated to alanine to explore the involvement of this region in the potentiation of ACh-induced currents by dFBr. ACh-induced responses obtained from wild-type and mutant alpha4beta2 receptors expressed in Xenopus laevis oocytes were recorded in the presence and absence of dFBr using two-electrode voltage clamp electrophysiology. Wild-type and mutant receptors were expressed in both high and low ACh sensitivity isoforms by using biased injection ratios of 1:5 or 5:1 alpha4 to beta2 complementary RNA. Mutations were made in the B, C, and A loops of the principal face of the beta2 subunit, which are regions not involved in the binding of ACh. Mutant beta2(Y120A) significantly eliminated dFBr potency in both isoform preparations. Several other mutations altered dFBr potentiation levels in both preparations. Our findings support the involvement of the principal face of the beta2 subunit in dFBr modulation of ACh-induced responses. Findings from this study will aid in the improved design of dFBr-like PAMs for potential therapeutic use.

Subject headings: Allosteric Site/drug effects/physiology; Animals; Dose-Response Relationship, Drug; Female; Humans; Hydrocarbons, Brominated/metabolism/pharmacology; Indole Alkaloids/metabolism/pharmacology; Protein Isoforms/agonists/metabolism; Protein Subunits/agonists/metabolism; Receptors, Nicotinic/metabolism; Xenopus laevis

Publication year: 2015

Journal or book title: The Journal of Pharmacology and Experimental Therapeutics

Volume: 354

Issue: 2

Pages: 184-194

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Type: Journal Article

Serial number: 1879