Potentiation of the homomeric rho1 GABAC receptor function by H2O2 is mediated by the intracellular cysteine residue Cys-364

ANDREA BELTRÁN GONZÁLEZ; JAVIER GASULLA; DANIEL J CALVO

Huerta Grande, Córdoba

Congreso; XXVI Congreso Anual de la Sociedad Argentina de Investigación en Neurociencias; 2011

Sociedad Argentina de Investigación en Neurociencias

Reactive oxygen species (ROS) are generated as by products of the cellular oxidative metabolism and secondary to the activation of NMDA and AMPA receptors. They are implicated in signalling pathways and oxidative stress, particularly during normal aging and neurodegenerative disorders. Numerous neurotransmitter receptors and ion channels are modulated by ROS. We reported previously that H2O2 significantly potentiates GABAC receptor function. In the present study we characterized the mechanism underlying this modulation. Homomeric GABArho1 receptors were expressed in Xenopus laevis oocytes and GABA-evoked chloride currents recorded by two-electrode voltage-clamp in the presence or absence of H2O2. Potentiation of GABArho1 receptors by H2O2 was dose-dependent, reversible, voltage independent and strongly depended on GABA concentration. GABArho1 receptors subunits contain three cysteine residues: two extracellular at the cys-loop (C177 and C191) and one intracellular (C364). Chemical protection of cysteine residues by the membrane-permeable sulfhydryl alkylating reagent (N-ethyl maleimide) prevented ROS potentiation. Furthermore, site directed mutagenesis of the intracellular cysteine by alanine (C364A) rendered receptors insensitive to H2O2, suggesting a single modulatory site.