β-amyloid directly inhibits human α4β3-nicotinic acetylcholine receptors heterologously expressed in human SH-EP1 cells

Jie Wut, Yen Ping Kuo, Andrew A. George, Lin Xu, Jun Hu, Ronald J. Lukas

Research output: Contribution to journalArticlepeer-review

97 Scopus citations

Abstract

Amyloid-β (Aβ) accumulation and aggregation are thought to contribute to the pathogenesis of Alzheimer's disease (AD). In AD, there is a selective decrease in the numbers of radioligand binding sites corresponding to the most abundant nicotinic acetylcholine receptor (nAChR) subtype, which contains human α4 and β2 subunits (hα4β2-nAChR). However, the relationships between these phenomena are uncertain, and effects of Aβ on hα4β2-nAChR function have not been investigated in detail. We first confirmed expression of hα4 and hβ2 subunits as messenger RNA in transfected, human SH-EP1 cells by reverse transcription-polymerase chain reaction and mRNA fluorescence in situ, hybridization analyses. Immunoprecipitation Western analyses confirmed α4 and β2 subunit protein expression and coassembly. Whole cell current recording demonstrated heterologous expression in SH-EP1-hα4β2 cells of functional hα4β2-nAChRs with characteristic responses to nicotinic agonists or antagonists. Nicotine-induced whole cell currents were suppressed by Aβ1-42 in a dose-dependent manner. Functional inhibition was selective for Aβ1-42compared with the functionally inactive, control peptide Aβ40-1. Aβ1-42-mediated inhibition of hα4β2-nAChR function was non-competitive, voltage-independent, and use-independent. Pre-loading of cells with guanyl-5′-yl thiophosphate failed to prevent Aβ1-42- induced inhibition, suggesting that down-regulation of hα4β2-nAChR function by Aβ1-42 is not mediated by nAChR intemalization. Sensitivity to Aβj_42 antagonism at 1 nM was evident for hα4β2-nAChRs, but not for heterologously expressed human α7-nAChRs, although both nAChR subtypes were functionally inhibited by 100 nM Aβ1-42, with the magnitude of functional block being higher for 100 nM Aβ1-42 acting on hα7-nAChRs. These findings suggest that hα4β2-nAChRs are sensitive and perhaps pathophysiologically relevant targets for Aβ neurotoxicity in AD.

Original languageEnglish (US)
Pages (from-to)37842-37851
Number of pages10
JournalJournal of Biological Chemistry
Volume279
Issue number36
DOIs
StatePublished - Sep 3 2004
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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