Oxidative Stress Regulation of Regulator of G‐Protein Signaling 4 (RGS4)

Abstract

Regulators of G‐protein signaling (RGS) proteins are a family of proteins that regulate G‐protein coupled receptors (GPCRs) by acting as GTPase accelerating proteins (GAPs). RGS proteins increase the rate of hydrolysis of GTP to GDP in select Gα subunits, including Gαo, Gαi, and Gαq but not Gαs. One of these proteins, RGS4, has been implicated in several neurological diseases. In this study, we analyze the effect of oxidative stress on RGS4 regulation in neuronal cells and the effect of lipid peroxidation products, such as 4‐hydroxy‐nonenal (4HNE), on RGS4 activity. Select RGS4 isoforms were induced during oxidative stress with H2O2. 4HNE forms covalent adducts on reactive amino acids such as cysteine. Previous research revealed that modification only occurs at select cysteine residues. Several mutants were made containing only one of the modified cysteines, either C71, C148, and, C183, and were treated with increasing amounts of 4HNE and then assayed for coupling to the native binding partner Gαo by ALPHA‐Screen. The wild type construct showed sensitivity to 4HNE but the cysteine null mutant did not. Of the single cysteine containing mutants, only C148 conferred sensitivity to RGS4. Research support provided by the Pharmacological Sciences Training Grant (NIH/NIGMST32GM067795).