Enhanced functional detection of synaptic calcium-permeable AMPA receptors using intracellular NASPM

Abstract
Data availability
Article and author information
Metrics

Abstract

Calcium-permeable AMPA-type glutamate receptors (CP-AMPARs) contribute to many forms of synaptic plasticity and pathology. They can be distinguished from GluA2-containing calcium-impermeable AMPARs by the inward rectification of their currents, which reflects voltage-dependent channel block by intracellular spermine. However, the efficacy of this weakly permeant blocker is differentially altered by the presence of AMPAR auxiliary subunits - including transmembrane AMPAR regulatory proteins, cornichons and GSG1L - which are widely expressed in neurons and glia. This complicates the interpretation of rectification as a measure of CP-AMPAR expression. Here we show that inclusion of the spider toxin analogue 1‑naphthylacetyl spermine (NASPM) in the intracellular solution results in complete block of GluA1-mediated outward currents irrespective of the type of associated auxiliary subunit. In neurons from GluA2-knockout mice expressing only CP-AMPARs, intracellular NASPM, unlike spermine, completely blocks outward synaptic currents. Thus, our results identify a functional measure of CP-AMPARs, that is unaffected by their auxiliary subunit content.

Data availability

All data generated during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 1, 2, 3, 4, 5, 6 and 7.

Article and author information

Author details

Ian D Coombs

Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Cécile Bats

Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Craig A Sexton

Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-7617-8361
Dorota Studniarczyk

Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Stuart G Cull-Candy

Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom

For correspondence
s.cull-candy@ucl.ac.uk

Competing interests
The authors declare that no competing interests exist.
Mark Farrant

Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom

For correspondence
m.farrant@ucl.ac.uk

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-9918-0376

Funding

Medical Research Council (MR/T002506/1)

Mark Farrant

Medical Research Council (MR/T002506/1)

Stuart G Cull-Candy

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: All procedures for the care and treatment of mice were in accordance with the Animals (Scientific Procedures) Act 1986 (licences PPL 70/8526 and P4114FCF5) and institutional animal care and use committee (IACUC) protocols at University College London.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.