title: RGS7 complex formation and colocalization with the Gbeta5 subunit in the adult rat brain and influence on Gbeta5gamma2-mediated PLCbeta signaling.
abstract: This study describes the colocalized distribution and dimeric complex formation between RGS7, a GTPase-activating protein for several heterotrimeric Galpha protein families, and the Gbeta5 subunit in the adult rat brain. Confocal dual immunofluorescence labeling studies indicated a broad regional specificity in the cellular coexpression between RGS7 and Gbeta5 within the cerebral cortical layers I and V-VI, hippocampal formation, caudate-putamen, medial habenula, most thalamic nuclei, and cerebellar molecular and granular layers. In all instances, Gbeta1-beta4 immunoreactivities exhibited no observable colocalization with RGS7, despite their widespread codistribution throughout similar neuronal networks. Coimmunoprecipitation studies confirmed the selective protein-protein interaction between RGS7 and Gbeta5 within brain regions that displayed immunohistochemical colocalization. The influence of RGS7 to modulate Gbeta5gamma2-mediated phosphatidyl inositol (PI) production was examined in COS-7-cotransfected cells. In the presence of Gbeta5gamma2 only, intracellular PI accumulation was increased by 25% above basal levels; addition of RGS7 produced no significant alteration in Gbeta5gamma2-mediated PI accumulation. A similar trend was exhibited when full-length RGS7 was substituted with an RGS7 construct lacking the Gbeta5-interacting region (G protein gamma-like domain; GGL domain) or with RGS4. In conclusion, RGS7/Gbeta5 dimers occurred within most brain regions in which both proteins were cellularly coexpressed. However, an influence of RGS7 on Gbeta5gamma2-mediated PLCbeta signaling activity was not apparent, athough this was in COS-7 cell transfection studies.
authors.affiliation: Neuroscience Department, Wyeth-Ayerst Research, Princeton, NJ 08543-8000, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Liang
authors.forename: H H
authors.initials: HH
authors.lastname: Chen
authors.forename: P G
authors.initials: PG
authors.lastname: Jones
authors.forename: X Z
authors.initials: XZ
authors.lastname: Khawaja
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D019556:COS Cells; D005455:Fluorescent Antibody Technique; D044387:GTP-Binding Protein beta Subunits; D019204:GTP-Binding Proteins; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D018613:Microscopy, Confocal; D054799:Phospholipase C beta; D020710:RGS Proteins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism*
chemical_list: D044387:GTP-Binding Protein beta Subunits; C490610:Gnb5 protein, rat; D007527:Isoenzymes; D020710:RGS Proteins; C492038:Rgs7 protein, mouse; C115771:Rgs7 protein, rat; D010738:Type C Phospholipases; D054799:Phospholipase C beta; C518043:Plcb4 protein, mouse; C518044:Plcb4 protein, rat; D019204:GTP-Binding Proteins; D020962:Heterotrimeric GTP-Binding Proteins