Expression and function of variants of human catecholamine transporters lacking the fifth transmembrane region encoded by exon 6

Chiharu Sogawa, Chieko Mitsuhata, Kei Kumagai-Morioka, Norio Sogawa, Kazumi Ohyama, Katsuya Morita, Katsuyuki Kozai, Toshihiro Dohi, Shigeo Kitayama

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Background: The transporters for dopamine (DAT) and norepinephrine (NET) are members of the Na+- and Cl--dependent neurotransmitter transporter family SLC6. There is a line of evidence that alternative splicing results in several isoforms of neurotransmitter transporters including NET. However, its relevance to the physiology and pathology of the neurotransmitter reuptake system has not been fully elucidated. Methodology/Principal Findings: We found novel isoforms of human DAT and NET produced by alternative splicing in human blood cells (DAT) and placenta (NET), both of which lacked the region encoded by exon 6. RT-PCR analyses showed a difference in expression between the full length (FL) and truncated isoforms in the brain and peripheral tissues, suggesting tissue-specific alternative splicing. Heterologous expression of the FL but not truncated isoforms of DAT and NET in COS-7 cells revealed transport activity. However, immunocytochemistry with confocal microscopy and a cell surface biotinylation assay demonstrated that the truncated as well as FL isoform was expressed at least in part in the plasma membrane at the cell surface, although the truncated DAT was distributed to the cell surface slower than FL DAT. A specific antibody to the Cterminus of DAT labeled the variant but not FL DAT, when cells were not treated with Triton for permeabilization, suggesting the C-terminus of the variant to be located extracellulary. Co-expression of the FL isoform with the truncated isoform in COS-7 cells resulted in a reduced uptake of substrates, indicating a dominant negative effect of the variant. Furthermore, an immunoprecipitation assay revealed physical interaction between the FL and truncated isoforms. Conclusions/Significance: The unique expression and function and the proposed membrane topology of the variants suggest the importance of isoforms of catecholamine transporters in monoaminergic signaling in the brain and peripheral tissues.

Original languageEnglish
Article numbere11945
JournalPLoS One
Volume5
Issue number8
DOIs
Publication statusPublished - 2010

Fingerprint

catecholamines
exons
Catecholamines
transporters
Exons
Protein Isoforms
alternative splicing
neurotransmitters
Alternative Splicing
Neurotransmitter Transport Proteins
cells
COS Cells
Tissue
biotinylation
brain
Assays
Brain
Norepinephrine Plasma Membrane Transport Proteins
immunocytochemistry
assays

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Expression and function of variants of human catecholamine transporters lacking the fifth transmembrane region encoded by exon 6. / Sogawa, Chiharu; Mitsuhata, Chieko; Kumagai-Morioka, Kei; Sogawa, Norio; Ohyama, Kazumi; Morita, Katsuya; Kozai, Katsuyuki; Dohi, Toshihiro; Kitayama, Shigeo.

In: PLoS One, Vol. 5, No. 8, e11945, 2010.

Research output: Contribution to journalArticle

Sogawa, C, Mitsuhata, C, Kumagai-Morioka, K, Sogawa, N, Ohyama, K, Morita, K, Kozai, K, Dohi, T & Kitayama, S 2010, 'Expression and function of variants of human catecholamine transporters lacking the fifth transmembrane region encoded by exon 6', PLoS One, vol. 5, no. 8, e11945. https://doi.org/10.1371/journal.pone.0011945
Sogawa, Chiharu ; Mitsuhata, Chieko ; Kumagai-Morioka, Kei ; Sogawa, Norio ; Ohyama, Kazumi ; Morita, Katsuya ; Kozai, Katsuyuki ; Dohi, Toshihiro ; Kitayama, Shigeo. / Expression and function of variants of human catecholamine transporters lacking the fifth transmembrane region encoded by exon 6. In: PLoS One. 2010 ; Vol. 5, No. 8.
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AU - Ohyama, Kazumi

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