Characterization of the effects of four HTR3B polymorphisms an human 5-HT3AB receptor expression and signalling

Karen Krzywkowski, Paul A. Davies, Andrew J. Irving, Hans Brauner-Osborne, Anders A. Jensen

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    Abstract

    Background 5-Hydroxytryptamine 3 (5-HT3) receptors mediate the fast excitatory neurotransmission of serotonin. In this study, we have characterized the effects of four naturally occurring, nonsynonymous variants of the human 5-HT3B subunit on expression and signalling properties of heteromeric 5-HT3AB receptors.

    Methods and results 5-HT3AB receptor signalling was studied in a fluorescence-based cell membrane potential assay and by electrophysiology. Expression levels of cotransfected epitope-tagged 5-HT3A and 5-HT3B subunits were determined using enzyme-linked immunosorbent assay and immunocytochemistry. In cells coexpressing 5-HT3A and 5-HT3B(I143T) subunits, cell surface expression levels of 5-HT3B in particular, and also 5-HT3A were markedly reduced compared with those of wild-type (WT) 5-HT3AB receptor-expressing cells. Electrophysiological recordings on cells coexpressing 5-HT3A and 5-HT3B(I143T) indicated cell surface expression of 5-HT3AB(1143T) receptors with macroscopic current kinetics similar to those of WT 5-HT3AB receptors but with 3-fold lower current densities. In the membrane potential assay, 5-HT3AB(I143T)-transfected cells exhibited signalling properties intermediate to those of WT 5-HT3AB and 5-HT3A receptors. Cotransfection of 5-HT3A, 5-HT3AB(I143T) and WT 5-HT3AB subunit cDNAs did not increase cell surface expression of the variant subunit nor did it restore WT 5-HT3AB receptor signalling completely in the membrane potential assay. In contrast to 5-HT3B(I143T), the 5-HT3B variants S1 56R, V183I and A223T did not give rise to significant changes in 5-HT3AB receptor expression or signalling properties.

    Conclusion 5-HT3B(I143T)-containing 5-HT3AB receptors display significantly reduced cell surface expression and different signalling properties compared with WT 5-HT3AB receptors. In contrast, three other 5-HT3B variants, S156R, V183I and A223T, do not appear to alter 5-HT3AB receptor expression or signalling. Pharmacogenetics and Genomics 18:1027-1040 (C) 2008 Wolters Kluwer Health | Lippincott Williams & Wilkins.

    Original languageEnglish
    Pages (from-to)1027-1040
    Number of pages14
    JournalPharmacogenetics and Genomics
    Volume18
    Issue number12
    DOIs
    Publication statusPublished - Dec 2008

    Keywords

    • 5-HT3A
    • 5-HT3AB
    • 5-HT3B
    • expression
    • function
    • ligand-gated ion channel
    • polymorphism
    • serotonin
    • single-nucleotide polymorphism
    • variant
    • NICOTINIC ACETYLCHOLINE-RECEPTORS
    • SEROTONIN-RECEPTOR
    • MAJOR DEPRESSION
    • HUMAN GENOME
    • SUBUNIT
    • GENE
    • 5-HYDROXYTRYPTAMINE
    • CHANNEL
    • HETEROGENEITY
    • MUTATIONS

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