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Methods for the Discovery of Novel Compounds Modulating a Gamma-Aminobutyric Acid Receptor Type A Neurotransmission
Published on: August 16, 2018
Positive Modulation of the Glycine Receptor by Means of Glycine Receptor-Binding Aptamers
Nancy Dekki Shalaly1, Eduardo Aneiros2, Michael Blank3
1Department of Neuroscience, AstraZeneca R&D, Södertälje, Sweden and Division of Protein Technology, School of Biotechnology, Royal Institute of Technology, Stockholm, Sweden ndekki@hotmail.com.
Abstract:
According to the gate control theory of pain, the glycine receptors (GlyRs) are putative targets for development of therapeutic analgesics. A possible approach for novel analgesics is to develop a positive modulator of the glycine-activated Cl(-) channels. Unfortunately, there has been limited success in developing drug-like small molecules to study the impact of agonists or positive modulators on GlyRs. Eight RNA aptamers with low nanomolar affinity to GlyRα1 were generated, and their pharmacological properties analyzed. Cytochemistry using fluorescein-labeled aptamers demonstrated GlyRα1-dependent binding to the plasma membrane but also intracellular binding. Using a fluorescent membrane potential assay, we could identify five aptamers to be positive modulators. The positive modulation of one of the aptamers was confirmed by patch-clamp electrophysiology on L(tk) cells expressing GlyRα1 and/or GlyRα1β. This aptamer potentiated whole-cell Cl(-) currents in the presence of low concentrations of glycine. To our knowledge, this is the first demonstration ever of RNA aptamers acting as positive modulators for an ion channel. We believe that these aptamers are unique and valuable tools for further studies of GlyR biology and possibly also as tools for assay development in identifying small-molecule agonists and positive modulators.
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