Immunohistochemical distribution of RGS7 protein and cellular selectivity in colocalizing with Gαq proteins in the adult rat brain

Xavier Z. Khawaja, Jin Jun Liang, Julie A. Saugstad, Philip G. Jones, Steven Harnish, P. Jeffrey Conn, Mark I. Cockett

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

Regulators of G protein signaling (RGS) proteins serve as potent GTPase- activating proteins for the heterotrimeric G proteins αi/o and αq/11. This study describes the immunohistochemical distribution of RGS7 throughout the adult rat brain and its cellular colocalization with Gαq/11, an important G protein-coupled receptor signal transducer for phospholipase Cβ-mediated activity. In general, both RGS7 and Gαq/11 displayed a heterogeneous and overlapping regional distribution. RGS7 immunoreactivity was observed in cortical layers I-VI, being most intense in the neuropil of layer I. In the hippocampal formation, RGS7 immunoreactivity was concentrated in the strata oriens, strata radiatum, mossy fibers, and polymorphic cells, with faint to nondetectable immunolabeling within the dentate gyrus granule cells and CA1- CA3 subfield pyramidal cells. Numerous diencephalic and brainstem nuclei also displayed dense RGS7 immunostaining. Dual immunofluorescence labeling studies with the two protein-specific antibodies indicated a cellular selectivity in the colocalization between RGS7 and Gαq/11 within many discrete brain regions, such as the superficial cortical layer I, hilus area of the hippocampal formation, and cerebellar Golgi cells. To assess the ability of Gαq/11-mediated signaling pathways to modulate dynamically RGS expression, primary cortical neuronal cultures were incubated with phorbol 12,13- dibutyrate, a selective protein kinase C activator. A time-dependent increase in levels of mRNA for RGS7, but not RGS4, was observed. Our results provide novel information on the region- and cell-specific pattern of distribution of RGS7 with the transmembrane signal transducer, Gαq/11. We also describe a possible RGS7-selective neuronal feedback adaptation on Gαq/11-mediated pathway function, which may play an important role in signaling specificity in the brain.

Original languageEnglish (US)
Pages (from-to)174-184
Number of pages11
JournalJournal of Neurochemistry
Volume72
Issue number1
DOIs
StatePublished - Jan 11 1999

Keywords

  • Brain localization
  • Confocal microscopy
  • Gαq/11
  • Immunohistochemistry
  • Rat
  • Regulator of G protein signaling 7

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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