Journal of Molecular Neuroscience

, Volume 26, Issue 1, pp 99–108 | Cite as

Identification of two further splice variants of GABABR1 characterizes the conserved micro-exon 4 as a hot spot for regulated splicing in the rat brain

  • Jethro Holter
  • Jeffrey Davies
  • Nathalie Leresche
  • Vincenzo Crunelli
  • David A. CarterEmail author
Original Article


Inhibitory neurotransmission in the mammalian brain is principally mediated by γ-aminobutyric acid (GABA) acting through different subtypes of cell membrane GABA receptor (GABAR). The expression of one GABAR gene, GABABR1, is distinguished by the expression of multiple splice variants that encode different isoforms of the receptor. In the present study, we have identified two novel GABABR1 variants, GABABR1h (R1h) and GABABR1i (R1i), which appear to arise from alternative splicing of the GABABR1 gene. The expression of R1h and R1i is differentially regulated in brain and peripheral tissues, but expression is not altered in the brain of a genetic model of absence epilepsy (GAERS rat [genetic absence epilepsy rat from Strasbourg]). Both the R1h and R1i variants exhibit a novel 80-bp insert downstream of exon 4 that is flanked by consensus splice sites, and both encode C-terminal-truncated proteins. The new insight into the family of GABABR1 variants gained from this study identifies exon 4 as a preferred locus, or hot spot for regulated splicing in the GABABR1 gene. This finding correlates with the micro-exonic nature of exon 4 (21 bp). Bioinformatic analysis of micro-exon 4 and its flanking pre-mRNA sequences has revealed multiple, potentially competitive, exonic splicing enhancers that provide a mechanistic basis for the preponderance of alternative splicing events at this locus. Conservation of GABABR1 micro-exon 4 across species suggests a conserved functional role, facilitating either N-terminal protein production or post-transcriptional gene regulation through regulated splicing coupled to transcript decay.

Index Entries

GABA GABAB receptor alternative splicing micro-exon absence epilepsy 


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  1. Altschul S. F., Gish W., Miller W., Myers E. W., and Lipman D. J. (1990) Basic local alignment search tool. J. Mol. Biol. 215, 403–410.PubMedGoogle Scholar
  2. Bettler B., Kaupmann K., Mosbacher J., and Gassmann M. (2004) Molecular structure and physiological functions of GABA(B) receptors. Physiol. Rev. 84, 835–867.PubMedCrossRefGoogle Scholar
  3. Cartegni L., Wang J., Zhu Z., Zhang M. Q., and Krainer A. R. (2003) ESEfinder: a web resource to identify exonic splicing enhancers. Nucleic Acids Res. 31, 3568–3571.PubMedCrossRefGoogle Scholar
  4. Crunelli V. and Leresche N. (2002) Childhood absence epilepsy: genes, channels, neurons and networks. Nat. Rev. Neurosci. 3, 371–382.PubMedCrossRefGoogle Scholar
  5. Danober L., Deransart C., Depaulis A., Vergnes M., and Marescaux C. (1998) Pathophysiological mechanisms of genetic absence epilepsy in the rat. Prog. Neurobiol. 55, 27–57.PubMedCrossRefGoogle Scholar
  6. Dredge B. K., Polydorides A. D., and Darnell R. B. (2001) The splice of life: alternative splicing and neurological disease. Nat. Rev. Neurosci. 2, 43–50.PubMedCrossRefGoogle Scholar
  7. Fairbrother W. G., Yeh R. F., Sharp P. A., and Burge C. B. (2002) Predictive identification of exonic splicing enhancers in human genes. Science 297, 1007–1013.PubMedCrossRefGoogle Scholar
  8. Glowinski J. and Iversen L. L. (1966) Regional studies of catecholamines in the rat brain. I. The disposition of [3H]norepinephrine, [3H]dopamine and [3H]dopa in various regions of the brain. J. Neurochem. 13, 655–669.PubMedCrossRefGoogle Scholar
  9. Green R. E., Lewis B. P., Hillman R. T., Blanchette M., Lareau L. F., Garnett A. T., et al. (2003) Widespread predicted nonsense-mediated mRNA decay of alternatively spliced transcripts of human normal and disease genes. Bioinformatics 19(Suppl. 1), 118–121.CrossRefGoogle Scholar
  10. Holter J., Carter D., Leresche N., Crunelli V., and Vincent P. (2005) A mutation in the TASK3 channel (KCNK9) in a genetic model of absence epilepsy. J. Mol. Neurosci. 25, 37–52.PubMedCrossRefGoogle Scholar
  11. Holter J. L., Humphries A., Crunelli V., and Carter D. A. (2001) Optimisation of methods for selecting candidate genes from cDNA array screens: application to rat brain punches and pineal. J. Neurosci. Methods 112, 173–184.PubMedCrossRefGoogle Scholar
  12. Johnson J. M., Castle J., Garrett-Engele P., Kan Z., Loerch P. M., Armour C. D., et al. (2003) Genome-wide survey of human alternative pre-mRNA splicing with exon junction microarrays. Science 302, 2141–2144.PubMedCrossRefGoogle Scholar
  13. Kato H. and Enjyoji K. (1991) Amino acid sequence and location of the disulfide bonds in bovine beta 2 glycoprotein I: the presence of five Sushi domains. Biochemistry 30, 11687–11694.PubMedCrossRefGoogle Scholar
  14. Kaupmann K., Huggel K., Heid J., Flor P. J., Bischoff S., Mickel S. J., et al. (1997) Expression cloning of GABA(B) receptors uncovers similarity to metabotropic glutamate receptors. Nature 386, 239–246.PubMedCrossRefGoogle Scholar
  15. Lewis B. P., Green R. E., and Brenner S. E. (2003) Evidence for the widespread coupling of alternative splicing and nonsense-mediated mRNA decay in humans. Proc. Natl. Acad. Sci. U. S. A. 100, 189–192.PubMedCrossRefGoogle Scholar
  16. Morgan H., Smith M., Burke Z., and Carter D. A. (2000) The transactivation-competentC-terminal domain of AF-9 is expressed within a sexually dimorphic transcript in rat pituitary. FASEB J. 14, 1109–1116.PubMedGoogle Scholar
  17. Purves D., Augustine G. J., Fitzpatrick D., Katz L. C., LaMantia A.-S., McNamara J. O., eds. (1997) in Neuroscience, Sinauer, Sunderland, MA: p. 111.Google Scholar
  18. Sambrook J., Fritsch E. F., and Maniatis T. (1989) Molecular Cloning: A Laboratory Mannual, 2nd ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY.Google Scholar
  19. Sorek R., Shamir R., and Ast G. (2004) How prevalent is functional alternative splicing in the human genome? Trends Genet. 20, 68–71.PubMedCrossRefGoogle Scholar
  20. Stamm S., Zhu J., Nakai K., Stoilov P., Stoss O., and Zhang M. Q. (2000) An alternative-exon database and its statistical analysis. DNA Cell Biol. 19, 739–756.PubMedCrossRefGoogle Scholar
  21. Volfovsky N., Haas B. J., and Salzberg S. L. (2003) Computational discovery of internal micro-exons. Genome Res. 13, 1216–1221.PubMedCrossRefGoogle Scholar
  22. Wei K., Eubanks J. H., Francis J., Jia Z., and Snead O. C. III (2001a) Cloning and tissue distribution of a novel isoform of the rat GABA(B)R1 receptor subunit. Neuroreport 12, 833–837.PubMedCrossRefGoogle Scholar
  23. Wei K., Jia Z., Wang Y. T., Yang J., Liu C. C., and Snead O. C. III (2001b) Cloning and characterization of a novel variant of rat GABA(B)R1 with a truncated C-terminus. Brain Res. Mol. Brain Res. 89, 103–110.PubMedCrossRefGoogle Scholar

Copyright information

© Humana Press Inc 2005

Authors and Affiliations

  • Jethro Holter
    • 1
  • Jeffrey Davies
    • 1
  • Nathalie Leresche
    • 2
  • Vincenzo Crunelli
    • 1
  • David A. Carter
    • 1
    Email author
  1. 1.School of BiosciencesCardiff UniversityCardiffUK
  2. 2.Equipe Neurobiologie Cellulaire, UMR 7102CNRS Université Paris VIParisFrance

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