RGS7 complex formation and colocalization with the Gbeta5 subunit in the adult rat brain and influence on Gbeta5gamma2-mediated PLCbeta signaling

J Neurosci Res. 2000 Apr 1;60(1):58-64. doi: 10.1002/(SICI)1097-4547(20000401)60:1<58::AID-JNR6>3.0.CO;2-L.

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.

MeSH terms

  • Animals
  • Brain / metabolism*
  • COS Cells
  • Fluorescent Antibody Technique
  • GTP-Binding Protein beta Subunits*
  • GTP-Binding Proteins*
  • Heterotrimeric GTP-Binding Proteins / metabolism*
  • Isoenzymes / metabolism*
  • Microscopy, Confocal
  • Phospholipase C beta
  • RGS Proteins / metabolism*
  • Rats
  • Rats, Wistar
  • Signal Transduction / physiology*
  • Transfection
  • Type C Phospholipases / metabolism*

Substances

  • GTP-Binding Protein beta Subunits
  • Gnb5 protein, rat
  • Isoenzymes
  • RGS Proteins
  • Rgs7 protein, mouse
  • Rgs7 protein, rat
  • Type C Phospholipases
  • Phospholipase C beta
  • Plcb4 protein, mouse
  • Plcb4 protein, rat
  • GTP-Binding Proteins
  • Heterotrimeric GTP-Binding Proteins