Title

α-Conotoxins Identify The α3β4ˆ— Subtype As The Predominant Nicotinic Acetylcholine Receptor Expressed In Human Adrenal Chromaffin Cells

Department

neurobiology

Document Type

Article

Abstract

Ligands that selectively inhibit human α3β2 and α6β2 nicotinic acetylcholine receptor (nAChRs) and not the closely related α3β4 and α6β4 subtypes are lacking. Current α-conotoxins (α-Ctxs) that discriminate among these nAChR subtypes in rat fail to discriminate among the human receptor homologs. In this study, we describe the development of α-Ctx LvIA(N9R,V10A) that is 3000-fold more potent on oocyte-expressed human α3b2 than α3b4 and 165-fold more potent on human a6/a3β2β3 than a6/ a3β4 nAChRs. This analog was used in conjuction with three other α-Ctx analogs and patch-clamp electrophysiology to characterize the nAChR subtypes expressed by human adrenal chromaffin cells. LvIA(N9R,V10A) showed little effect on the acetylcholine-evoked currents in these cells at concentrations expected to inhibit nAChRs with β2 ligand-binding sites. In contrast, the b4-selective α-Ctx BuIA(T5A,P6O) inhibited .98% of the acetylcholine-evoked current, indicating that most of the heteromeric receptors contained b4 ligand-binding sites. Additional studies using the α6-selective α-Ctx PeIA(A7V,S9H,V10A, N11R,E14A) indicated that the predominant heteromeric nAChR expressed by human adrenal chromaffin cells is the a3b4∗ subtype (asterisk indicates the possible presence of additional subunits). This conclusion was supported by polymerase chain reaction experiments of human adrenal medulla gland and of cultured human adrenal chromaffin cells that demonstrated prominent expression of RNAs for α3, α5, α7, β2, and β4 subunits and a low abundance of RNAs for α2, α4, α6, and α10 subunits.

Publication Date

11-1-2015

Publication Title

Molecular Pharmacology

ISSN

0026895X

Volume

88

Issue

5

First Page

881

Last Page

893

Digital Object Identifier (DOI)

10.1124/mol.115.100982

This document is currently not available here.

Share

COinS