Differential Dependence of the D1 and D5 Dopamine Receptors on the G Protein γ7 Subunit for Activation of Adenylylcyclase

Qin Wang, Julian P. Jolly, James D. Surmeier, Bashar M. Mullah, Michael S. Lidow, Clare M Bergson, Janet D. Robishaw

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Abstract

The D1 dopamine receptor, G protein γ7 subunit, and adenylylcyclase are selectively expressed in the striatum, suggesting their potential interaction in a common sig naling pathway. To evaluate this possibility, a ribozyme strategy was used to suppress the expression of the G protein γ7 subunit in HEK 293 cells stably expressing the human D1 dopamine receptor. Prior in vitro analysis revealed that the γ7 ribozyme possessed cleavage activity directed exclusively toward the γ7 RNA transcript (Wang, Q., Mullah, B., Hansen, C., Asundi, J., and Robishaw, J. D. (1997) J. Biol. Chem. 272, 26040-26048). In vivo analysis of cells transfected with the γ 7 ribozyme showed a specific reduction in the expression of the γ7 protein. Coincident with the loss of the γ 7 protein, there was a noticeable reduction in the expression of the β1 protein, confirming their interaction in these cells. Finally, functional analysis of ribozyme-mediated suppression of the β 1 and γ7 proteins revealed a significant attenuation of SKF81297-stimulated adenylylcyclase activity in D1 dopamine receptor-expressing cells. By contrast, ribozyme-mediated suppression of the β1 and γ7 proteins showed no reduction of SKF81297-stimulated adenylylcyclase activity in D5 dopamine receptor-expressing cells. Taken together, these data indicate that the structurally related D1 and D5 dopamine receptor subtypes utilize G proteins composed of distinct βγ subunits to stimulate adenylylcyclase in HEK 293 cells. Underscoring the physiological relevance of these findings, single cell reverse transcriptase-polymerase chain reaction analysis revealed that the D1 dopamine receptor and the G protein γ7 subunit are coordinately expressed in substance P containing neurons in rat striatum, suggesting that the G protein γ 7 subunit may be a new target for drugs to selectively alter dopaminergic signaling within the brain.

Original languageEnglish (US)
Pages (from-to)39386-39393
Number of pages8
JournalJournal of Biological Chemistry
Volume276
Issue number42
DOIs
StatePublished - Oct 19 2001

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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