Differential Dependence of the D1 and D5Dopamine Receptors on the G Protein γ7 Subunit for Activation of Adenylylcyclase
The D 1 dopamine receptor, G protein γ 7 subunit, and adenylylcyclase are selectively expressed in the striatum, suggesting their potential interaction in a common signaling pathway. To evaluate this possibility, a ribozyme strategy was used to suppress the expression of the G protein γ 7 subunit...
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Veröffentlicht in: | The Journal of biological chemistry 2001-10, Vol.276 (42), p.39386 |
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Sprache: | eng |
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Zusammenfassung: | The D 1 dopamine receptor, G protein γ 7 subunit, and adenylylcyclase are selectively expressed in the striatum, suggesting their potential interaction in a common
signaling pathway. To evaluate this possibility, a ribozyme strategy was used to suppress the expression of the G protein
γ 7 subunit in HEK 293 cells stably expressing the human D 1 dopamine receptor. Prior in vitro analysis revealed that the γ 7 ribozyme possessed cleavage activity directed exclusively toward the γ 7 RNA transcript (Wang, Q., Mullah, B., Hansen, C., Asundi, J., and Robishaw, J. D. (1997) J. Biol. Chem. 272, 26040â26048). In vivo analysis of cells transfected with the γ 7 ribozyme showed a specific reduction in the expression of the γ 7 protein. Coincident with the loss of the γ 7 protein, there was a noticeable reduction in the expression of the β 1 protein, confirming their interaction in these cells. Finally, functional analysis of ribozyme-mediated suppression of the
β 1 and γ 7 proteins revealed a significant attenuation of SKF81297-stimulated adenylylcyclase activity in D 1 dopamine receptor-expressing cells. By contrast, ribozyme-mediated suppression of the β 1 and γ 7 proteins showed no reduction of SKF81297-stimulated adenylylcyclase activity in D 5 dopamine receptor-expressing cells. Taken together, these data indicate that the structurally related D 1 and D 5 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 D 1 dopamine receptor and the G protein γ 7 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. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M104981200 |