An intracellular redox sensor for reactive oxygen species at the M3-M4 linker of GABAA ρ1 receptors.

BELTRÁN GONZÁLEZ AN, GASULLA J, CALVO DJ.

BRITISH JOURNAL OF PHARMACOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2014 vol. 171 p. 2291 - 2299

0007-1188

BACKGROUND AND PURPOSEReactive oxygen species (ROS) are normally involved in cell oxidative stress but also play a role as cellular messengers in redoxsignalling; for example, modulating the activity of neurotransmitter receptors and ion channels. However, the direct actions ofROS on GABAA receptors were not previously demonstrated. In the present work, we studied the effects of ROS on GABAAρ1receptor function.EXPERIMENTAL APPROACHGABAAρ1 receptors were expressed in oocytes and GABA-evoked responses electrophysiologically recorded in the presence orabsence of ROS. Chemical protection of cysteines by selective sulfhydryl reagents and site-directed mutagenesis studies wereused to identify protein residues involved in ROS actions.KEY RESULTSGABAAρ1 receptor-mediated responses were significantly enhanced in a concentration-dependent and reversible manner byH2O2. 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 (C177 and C191) and oneintracellular (C364) at the M3-M4 linker. Mutant GABAAρ1 receptors in which C364 was exchanged by alanine were completelyinsensitive to modulation, implying that this site, rather than a cysteine in the Cys-loop, is essential for ROS modulation.CONCLUSION AND IMPLICATIONSOur results show that the function of GABAAρ1 receptors is enhanced by ROS and that the intracellular C364 is the sensor forROS actions.