title: Water soluble RNA based antagonist of AMPA receptors.
abstract: Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are one of the important receptor classes involved in glutamate-mediated excitotoxicity. Although small molecule antagonists of this receptor have been shown to have neuroprotective properties, their low solubilities pose severe side effects in clinical trials. Here we have used the SELEX method to obtain water-soluble nuclease-resistant RNA ligands that bind to the agonist binding site of AMPA receptors. Using whole-cell current recordings, we have characterized the functional consequences of a representative aptamer from this class and show that it is a competitive antagonist of AMPA receptors and in the concentration range where it acts as an inhibitor of the AMPA receptor the RNA has no effect on the GluR6 homomeric kainate receptors. Additionally, using a fluorescence resonance energy transfer (FRET) probe, we show that this RNA ligand stabilizes the open cleft conformation of the ligand binding domain, consistent with the known structures of small antagonist-bound states of the soluble domain of this protein. Finally, using rat primary cortical neurons, we show that this RNA ligand significantly reduces neurotoxicity associated with oxygen glucose deprivation. The water-soluble and antagonistic properties of this aptamer coupled with its neuroprotective properties make it an excellent candidate for potential use in diseases or pathological conditions involving glutamate-mediated excitotoxicity.
authors.affiliation: 6431 Fannin, Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX 77030, USA.
authors.forename: Mei
authors.initials: M
authors.lastname: Du
authors.forename: Henning
authors.initials: H
authors.lastname: Ulrich
authors.forename: Xiurong
authors.initials: X
authors.lastname: Zhao
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Aronowski
authors.forename: Vasanthi
authors.initials: V
authors.lastname: Jayaraman
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004622:Embryo, Mammalian; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D005947:Glucose / Q000172:deficiency; D018698:Glutamic Acid / Q000494:pharmacology; D000860:Hypoxia; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D019579:Neocortex / Q000166:cytology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques / Q000379:methods; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D011487:Protein Conformation; D051381:Rats; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors* / Q000502:physiology*; D052156:SELEX Aptamer Technique / Q000379:methods; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D052157:Aptamers, Nucleotide; D018091:Receptors, AMPA; D013778:Tetrazolium Salts; D013844:Thiazoles; D018698:Glutamic Acid; C022616:thiazolyl blue; D005947:Glucose