Tetrapeptide Ac-HAEE-NH2 Protects α4β2 nAChR from Inhibition by Aβ.

Evgeny P Barykin,Anastasia A Anashkina,Alexander A Makarov,Irina V Shelukhina,Victor I Tsetlin,Sergey A Kozin,Aleksandra I Garifulina,Yuri V Mezentsev,Alexei A Adzhubei,Anna P Tolstova

doi:10.3390/ijms21176272

Abstract

The cholinergic deficit in Alzheimer’s disease (AD) may arise from selective loss of cholinergic neurons caused by the binding of Aβ peptide to nicotinic acetylcholine receptors (nAChRs). Thus, compounds preventing such an interaction are needed to address the cholinergic dysfunction. Recent findings suggest that the 11EVHH14 site in Aβ peptide mediates its interaction with α4β2 nAChR. This site contains several charged amino acid residues, hence we hypothesized that the formation of Aβ-α4β2 nAChR complex is based on the interaction of 11EVHH14 with its charge-complementary counterpart in α4β2 nAChR. Indeed, we discovered a 35HAEE38 site in α4β2 nAChR, which is charge-complementary to 11EVHH14, and molecular modeling showed that a stable Aβ42-α4β2 nAChR complex could be formed via the 11EVHH14:35HAEE38 interface. Using surface plasmon resonance and bioinformatics approaches, we further showed that a corresponding tetrapeptide Ac-HAEE-NH2 can bind to Aβ via 11EVHH14 site. Finally, using two-electrode voltage clamp in Xenopus laevis oocytes, we showed that Ac-HAEE-NH2 tetrapeptide completely abolishes the Aβ42-induced inhibition of α4β2 nAChR. Thus, we suggest that 35HAEE38 is a potential binding site for Aβ on α4β2 nAChR and Ac-HAEE-NH2 tetrapeptide corresponding to this site is a potential therapeutic for the treatment of α4β2 nAChR-dependent cholinergic dysfunction in AD.

Highlights

Alzheimer’s disease (AD) is the most common neurodegenerative disorder with over 50 million of patients worldwide [1]
Existing data suggest that the interaction of Aβ with α4β2 and α7 nicotinic acetylcholine receptors (nAChRs) leads to selective loss of cholinergic neurons and cholinergic deficit, which is a hallmark of AD [13]
To find the charged counterparts for 11EVHH14 in α7 or α4β2 nAChRs, we used the ScanProsite tool [19] (See Methods). Two such motifs were detected in α4 nAChR subunit, 35HAEE38 and 579KAED582, of which KAED is in the cytoplasmic domain, and HAEE is located in the extracellular part of α4 subunit

Summary

Introduction

Alzheimer’s disease (AD) is the most common neurodegenerative disorder with over 50 million of patients worldwide [1]. Α4β2 and α7 nAChRs are the most abundant types of nAChRs that regulate memory, sleep, pain and cognitive processes [8,9,10]. Their activation triggers intracellular signaling, including survival-related pathways, whereas their dysfunction leads to synaptic impairment and neuronal death [11,12]. Compounds that prevent the interaction of Aβ with nAChRs could reduce neuronal loss and cognitive decline in AD. To develop such targeted compounds, we need extensive knowledge about the structure and function of Aβ-nAChR complexes and their interaction interfaces

Methods

Results

Conclusion