title: Brain-specific RGS9-2 is localized to the nucleus via its unique proline-rich domain.
abstract: Brain-specific regulator of G protein signaling 9 (RGS9-2) is a member of a family of proteins that can function as GTPase-activating proteins for heterotrimeric G proteins. In the present study, we examined the intracellular distribution of RGS9-2 in native brain tissue and transfected cells. Immunocytochemical and immunoblot experiments revealed an unexpectedly high proportion of RGS9-2 within the nuclei of forebrain neurons. A similar intracellular distribution was seen in transfected COS-7 cells. The RGS9 binding partner G(beta5) further enhanced the nuclear localization of RGS9-2, but did not affect the strongly cytoplasmic localization of RGS9-1, the retinal form of RGS9. Deletion construct analysis revealed that the unique polyproline-rich C-terminus of brain-specific RGS9-2 contains sequences necessary and sufficient to target RGS9 to the nucleus of COS-7 cells, as well as cultured striatal neurons. Furthermore, RGS9-2 transfection increased the transcriptional activity of a neuronal gene construct normally expressed in RGS9-positive neurons, suggesting that nuclear RGS9 directly or indirectly regulates transcription in vivo. The nuclear localization of RGS9-2 suggests a heretofore-unanticipated role for this brain-specific protein in transducing signals to the nuclei of forebrain neurons.
authors.affiliation: Department of Psychiatry, Wayne State University School of Medicine, 540 E. Canfield, 2309 Scott Hall, Detroit, MI 48201, USA.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Bouhamdan
authors.forename: Sharon Kay
authors.initials: SK
authors.lastname: Michelhaugh
authors.forename: Irina
authors.initials: I
authors.lastname: Calin-Jageman
authors.forename: Shawn
authors.initials: S
authors.lastname: Ahern-Djamali
authors.forename: Michael John
authors.initials: MJ
authors.lastname: Bannon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D044387:GTP-Binding Protein beta Subunits / Q000378:metabolism; D008297:Male; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins / Q000378:metabolism; D011392:Proline / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D020710:RGS Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016415:Sequence Alignment; D013347:Subcellular Fractions / Q000737:chemistry / Q000378:metabolism
chemical_list: D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D044387:GTP-Binding Protein beta Subunits; C490610:Gnb5 protein, rat; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; D020710:RGS Proteins; C116925:regulator of g-protein signaling 9; D011392:Proline