A kainate receptor–selective RNA aptamer

William Jaremko,Zhen Huang,Nicholas Karl,Vincen D Pierce,Janet Lynch,Li Niu

doi:10.1074/jbc.ra119.011649

William Jaremko, Zhen Huang + Show 4 more

Open Access

https://doi.org/10.1074/jbc.ra119.011649

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Abstract

Kainate and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are two major, closely related receptor subtypes in the glutamate ion channel family. Excessive activities of these receptors have been implicated in a number of central nervous system diseases. Designing potent and selective antagonists of these receptors, especially of kainate receptors, is useful for developing potential treatment strategies for these neurological diseases. Here, we report on two RNA aptamers designed to individually inhibit kainate and AMPA receptors. To improve the biostability of these aptamers, we also chemically modified these aptamers by substituting their 2'-OH group with 2'-fluorine. These 2'-fluoro aptamers, FB9s-b and FB9s-r, were markedly resistant to RNase-catalyzed degradation, with a half-life of ∼5 days in rat cerebrospinal fluid or serum-containing medium. Furthermore, FB9s-r blocked AMPA receptor activity. Aptamer FB9s-b selectively inhibited GluK1 and GluK2 kainate receptor subunits, and also GluK1/GluK5 and GluK2/GluK5 heteromeric kainate receptors with equal potency. This inhibitory profile makes FB9s-b a powerful template for developing tool molecules and drug candidates for treatment of neurological diseases involving excessive activities of the GluK1 and GluK2 subunits.

Highlights

Kainate and ␣-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are two major, closely related receptor subtypes in the glutamate ion channel family
Ionotropic glutamate receptors mediate the majority of excitatory neurotransmission in the mammalian central nervous system (CNS), and they are essential for brain development and function [1]
As an alternative to synthetic chemistry, which yields small molecule inhibitors, we have previously used systematic evolution of ligands by exponential enrichment (SELEX) to “evolve” RNA molecules bound to target from a large library (ϳ1014 sequence variations)

Summary

ARTICLE cro

Aptamer FB9s-b selectively inhibited GluK1 and GluK2 kainate receptor subunits, and GluK1/GluK5 and GluK2/ GluK5 heteromeric kainate receptors with equal potency This inhibitory profile makes FB9s-b a powerful template for developing tool molecules and drug candidates for treatment of neurological diseases involving excessive activities of the GluK1 and GluK2 subunits. A chemically modified aptamer selective to kainate receptors potential drug candidates targeting GluK2 or GluK2-containing channels by the use of structure-based ligand discovery has been just as elusive. We report an RNA inhibitor or RNA aptamer, termed AB9s-b This aptamer shows a micromolar potency in inhibiting the GluK2 kainate receptor subunit and GluK2/GluK5 channels. RNA aptamers are water-soluble and in general show higher potency and selectivity To make these RNA aptamers amenable for in vivo use, we have developed its chemically modified aptamer, FB9s-b, with satisfactory in vitro stability in the presence of ribonucleases, as in cerebrospinal fluid (CSF)

Experimental procedures

Discussion

Data analysis

RNA digestion assay