Molecular Characterization of Human and Rat RGS 9L, a Novel Splice Variant Enriched in Dopamine Target Regions, and Chromosomal Localization of the RGS 9 Gene
- James G. Granneman1,
- Ying Zhai1,
- Zhengxian Zhu1,
- Michael J. Bannon1,
- Scott A. Burchett1,
- Carl J. Schmidt2,
- Rodrigo Andrade1 and
- James Cooper1
- 1Department of Psychiatry and Behavioral Neuroscience, Wayne State University School of Medicine, Detroit, Michigan 48201 (J.G.G., Y.Z., Z.Z., M.J.B., S.A.B., R.A., J.C.), and 2Office of the Wayne County Medical Examiner, Detroit, Michigan 48207 (C.J.S.)
Abstract
A novel splice variant of RGS 9 was isolated from a rat hypothalamus, human retina, and a human kidney (Wilm’s) tumor. This variant, termed RGS 9L, differs from the retinal form (termed RGS 9S) identified previously in that it contains a 211- (rat) or 205- (human) amino acid proline-rich domain on the carboxyl terminus. The pattern of RGS 9 mRNA splicing was tissue specific, with striatum, hypothalamus- and nucleus accumbens expressing RGS 9L, whereas retina and pineal expressed RGS 9S almost exclusively. This pattern of mRNA splicing seemed to be highly conserved between human and rodents, suggesting cell-specific differences in the function of these variants. Transient expression of RGS 9L augmented basal and β-adrenergic receptor-stimulated adenylyl cyclase activity while suppressing dopamine D2receptor-mediated inhibition. Furthermore, RGS 9L expression greatly accelerated the decay of dopamine D2 receptor-induced GIRK current. These results indicate RGS 9L inhibits heterotrimeric Gi function in vivo, probably by acting as a GTPase-activating protein. The human RGS 9 gene was localized to chromosome 17 q23–24 by radiation hybrid and fluorescent in situ hybridization analyses. The RGS 9 gene is within a previously defined locus for retinitis pigmentosa (RP 17), a disease that has been linked to genes in the rhodopsin/transducin/cGMP signaling pathway.
Footnotes
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Send reprint requests to: Dr. James Granneman, Cell Biology, Parke-Davis Research Labs, 2800 Plymouth Road, Ann Arbor, MI 48105.
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This work was supported by National Institutes of Health Grants DK46339 and DK37006 (J.G.G.), DA06470 and NS34935 (M.J.B.), and MH43985 (R.A.).
- Abbreviations:
- RGS
- regulator of G proteinsignaling
- rRGS
- rat regulator of B protein signaling
- PCR
- polymerase chain reaction
- RT
- reverse transcription
- RACE
- rapid amplification of cDNA ends
- CHO
- Chinese hamster ovary
- EGTA
- ethylene glycol bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid
- HEPES
- 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- AR
- adrenergic receptor
- nt
- nucleotide(s)
- FISH
- fluorescence in situ hybridization
- PDE
- phosphodiesterase
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- Received May 1, 1998.
- Accepted June 18, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
