A Na+-phosphate cotransporter homologue (SLC17A4 protein) is an intestinal organic anion exporter

Natsuko Togawa, Takaaki Miyaji, Sho Izawa, Hiroshi Omote, Yoshinori Moriyama

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

The SLC17 anion transporter family comprises nine members that transport various organic anions in membrane potential (Δψ)- and Cl--dependent manners. Although the transport substrates and physiological relevance of the majority of the members have already been determined, little is known about SLC17A4 proteins known to be Na+-phosphate cotransporter homologue (NPT homologue). In the present study, we investigated the expression and transport properties of human SLC17A4 protein. Using specific antibodies, we found that a human NPT homologue is specifically expressed and present in the intestinal brush border membrane. Proteoliposomes containing the purified protein took up radiolabeled p-aminohippuric acid (PAH) in a Cl--dependent manner at the expense of an electrochemical gradient of protons, especially Δψ, across the membrane. The Δψ- and Cl--dependent PAH uptake was inhibited by diisothiocyanostilbene-2,2′-disulfonic acid and Evans blue, common inhibitors of SLC17 family members. cis-Inhibition studies revealed that various anionic compounds, such as hydrophilic nonsteroidal anti-inflammatory drugs, pravastatin, and urate inhibited the PAH uptake. Proteoliposomes took up radiolabeled urate, with the uptake having properties similar to those of PAH uptake. These results strongly suggested that the human NPT homologue acts as a polyspecific organic anion exporter in the intestines. Since SLC17A1 protein (NPT1) and SLC17A3 protein (NPT4) are responsible for renal urate extrusion, our results reveal the possible involvement of a NPT homologue in urate extrusion from the intestinal duct.

Original languageEnglish
Pages (from-to)1652-1660
Number of pages9
JournalAmerican Journal of Physiology - Cell Physiology
Volume302
Issue number11
DOIs
Publication statusPublished - Jun 1 2012

Keywords

  • Chloride ion
  • Intestine
  • Na-phosphate cotransporter homologue
  • Organic anion transporter
  • Urate

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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