An intracellular redox sensor for reactive oxygen species at the M3‐M4 linker of GABAAρ1 receptors. (May 2014)

• Record Type: Journal Article
• Authors: Beltrán González, Andrea N; Gasulla, Javier; Calvo, Daniel J
• Is Part Of: British journal of pharmacology. Volume 171:Number 9(2014:May)
• Page Start: 2291
• Page End: 2299
• Publication Date: 2014-05
• Subjects: Pharmacology -- Periodicals; Chemotherapy -- Periodicals; Drug Therapy -- Periodicals; Pharmacology -- Periodicals; 615.1
• DOI: 10.1111/bph.12581
• Languages: English
• ISSNs: 0007-1188

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="bph12581-sec-0001" sec-type="section"> <title>Background and Purpose</title> <p>Reactive oxygen species (ROS) are normally involved in cell oxidative stress but also play a role as cellular messengers in redox signalling; for example, modulating the activity of neurotransmitter receptors and ion channels. However, the direct actions of ROS on GABA<sub>A</sub> receptors were not previously demonstrated. In the present work, we studied the effects of ROS on GABA<sub>A</sub>ρ1 receptor function.</p> </sec> <sec id="bph12581-sec-0002" sec-type="section"> <title>Experimental Approach</title> <p>GABA<sub>A</sub>ρ1 receptors were expressed in oocytes and GABA‐evoked responses electrophysiologically recorded in the presence or absence of ROS. Chemical protection of cysteines by selective sulfhydryl reagents and site‐directed mutagenesis studies were used to identify protein residues involved in ROS actions.</p> </sec> <sec id="bph12581-sec-0003" sec-type="section"> <title>Key Results</title> <p>GABA<sub>A</sub>ρ1 receptor‐mediated responses were significantly enhanced in a concentration‐dependent and reversible manner by H<sub>2</sub>O<sub>2</sub>. Potentiating effects were attenuated by a free radical scavenger, lipoic acid or an inhibitor of the Fenton reaction, deferoxamine. Each ρ1 subunit contains only three cysteine residues, two extracellular at the Cys‐loop (C<sup>177</sup> and C<sup>191</sup>) and one intracellular (C<sup>364</sup>) at the M3‐M4 linker. Mutant GABA<sub>A</sub>ρ1 receptors in which C<sup>364</sup> was exchanged by alanine were completely insensitive to modulation, implying that this site, rather than a cysteine in the Cys‐loop, is essential for ROS modulation.</p> </sec> <sec id="bph12581-sec-0004" sec-type="section"> <title>Conclusion and Implications</title> <p>Our results show that the function of GABA<sub>A</sub>ρ1 receptors is enhanced by ROS and that the intracellular C<sup>364</sup> is the sensor for ROS actions.</p> </sec> </abstract>