title: Isolation and characterization of a novel human RGS mutant displaying gain-of-function activity.
abstract: Regulator of G protein signaling (RGS) proteins play a crucial role in the adaptation of cells to stimulation by G protein-coupled receptors via heterotrimeric G proteins. Alterations in RGS function have been implicated in a wide range of disease states, leading to many researchers focusing on controlling the action of these regulatory proteins. Previous studies have centered on reducing or inhibiting the action of RGS proteins, utilizing inactive mutants or small molecular RGS inhibitors. Here we describe the isolation and characterization of a novel human RGS4 mutant which displays enhanced or gain-of-function (GOF) activity. RGS4(S30C) demonstrates GOF activity both in an in vivo yeast-based signalling pathway and in vitro against the Galpha(o1) subunit contained in an alpha(2A)-adrenoreceptor-Galpha(o1)(C351I) fusion protein. Mutational analysis of serine 30 identified a number of alternative substitutions that result in GOF activity. GOF activity was retained upon transposition of the serine 30-cysteine mutation to the equivalent serine residue in human RGS16. As with previously identified GOF mutants, RGS4(S30C/S30F/S30K) demonstrate increased steady state protein levels, however these mutants also demonstrate enhanced GAP activity through an additional mechanism distinct from the increased protein content. The identification of human RGS mutants with GOF activity may provide novel therapeutic agents for the treatment of signaling-based diseases and the ability to transpose these mutations to other human RGS proteins extends their application to multiple pathways.
authors.affiliation: Department of Biological Sciences, University of Warwick, Coventry, CV4 7AL, UK. Claire.L.Hill@warwick.ac.uk
authors.forename: Claire
authors.initials: C
authors.lastname: Hill
authors.forename: Zoe
authors.initials: Z
authors.lastname: Brownlie
authors.forename: John
authors.initials: J
authors.lastname: Davey
authors.forename: Graeme
authors.initials: G
authors.lastname: Milligan
authors.forename: Graham
authors.initials: G
authors.lastname: Ladds
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D017124:Conserved Sequence; D004252:DNA Mutational Analysis; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D017930:Genes, Reporter; D006801:Humans; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000302:isolation & purification* / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010675:Pheromones / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D020710:RGS Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000166:cytology / Q000187:drug effects; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism; D012694:Serine
chemical_list: D050505:Mutant Proteins; D010675:Pheromones; D020710:RGS Proteins; D029702:Schizosaccharomyces pombe Proteins; C098799:RGS4 protein; D012694:Serine; D020558:GTP Phosphohydrolases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D004837:Epinephrine