Exp Mol Med.  2008 Oct;40(5):505-513. 10.3858/emm.2008.40.5.505.

Co-localization and interaction of human organic anion transporter 4 with caveolin-1 in primary cultured human placental trophoblasts

• Lee WK
• Choi JK
• Cha SH

• KMID: 1104804
• DOI: http://doi.org/10.3858/emm.2008.40.5.505

Abstract

The human organic anion transporter 4 (hOAT4) has been identified as the fourth isoform of OAT family. hOAT4 contributes to move several negatively charged organic compounds between cells and their extracellular milieu. The functional characteristics and regulatory mechanisms of hOAT4 remain to be elucidated. It is well known that caveolin plays a role in modulating proteins having some biological functions. To address this issue, we investigated the co-localization and interaction between hOAT4 and caveolin-1. hOAT4 and caveolin-1 (mRNA and protein expression) were observed in cultured human placental trophoblasts isolated from placenta. The confocal microscopy of immuno-cytochemistry using primary cultured human trophoblasts showed hOAT4 and caveolin-1 were co-localized at the plasma membrane of the cell. This finding was confirmed by Western blot analysis using isolated caveolae-enriched membrane fractions and immune-precipitates from the trophoblasts. When synthesized cRNA of hOAT4 along with scrambled- or antisense-oligodeoxynucleotide (ODN) of Xenopus caveolin-1 were co-injected to Xenopus oocytes, the [3H]estrone sulfate uptake was significantly decreased by the co-injection of antisense ODN but not by scrambled ODN. These findings suggest that hOAT4 and caveolin-1 share a cellular expression in the plasma membrane and caveolin-1 up-regulates the organic anionic compound uptake by hOAT4 under the normal physiological condition.

Keyword

caveolin 1; estrone sulfate; organic anion transporter 4

MeSH Terms

Animals
Caveolin 1/genetics/*metabolism
Cells, Cultured
Female
Humans
Immunohistochemistry
Immunoprecipitation
Microscopy, Confocal
Models, Biological
Oocytes/metabolism
Organic Anion Transporters/genetics/*metabolism
Placenta/cytology
Protein Binding
Reverse Transcriptase Polymerase Chain Reaction
Trophoblasts/cytology/*metabolism
Xenopus