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PDZK1 regulates organic anion transporting polypeptide Oatp1a in mouse small intestine

Tomoko Sugiura1, Toru Otake, Takuya Shimizu

  • 1Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan.

Drug Metabolism and Pharmacokinetics
|November 19, 2010
PubMed

Insights

The PDZ domain protein PDZK1 facilitates the absorption of estrone-3-sulfate in the small intestine by interacting with organic anion transporting polypeptide 1a5 (Oatp1a5). This interaction is crucial for Oatp1a5

Area of Science:

  • Pharmacology
  • Molecular Biology
  • Gastroenterology

Background:

  • Organic anion transporting polypeptides (OATPs) are present on the apical surface of the small intestine.
  • The role of regulatory proteins in small intestinal OATP function is largely unknown.

Purpose of the Study:

  • To investigate the interaction between OATP and the PDZ protein PDZK1 in the mouse small intestine.
  • To determine the role of PDZK1 in the intestinal transport of estrone-3-sulfate (E3S).

Main Methods:

  • Intraduodenal administration of [³H]estrone-3-sulfate (E3S) in wild-type and pdzk1 gene knockout mice.
  • Ussing-type chamber experiments to assess E3S uptake.
  • Immunohistochemistry to determine protein localization.
  • Immunoprecipitation to confirm protein interaction.

Main Results:

  • Intestinal absorption and portal vein levels of [³H]E3S were significantly lower in pdzk1(-/-) mice compared to wild-type mice.
  • Uptake of [³H]E3S from the apical side was reduced in intestinal tissues of pdzk1(-/-) mice.
  • PDZK1 physically interacts with Oatp1a, and its absence leads to reduced apical localization of Oatp1a protein.

Conclusions:

  • PDZK1 acts as an adaptor protein for Oatp1a in the small intestine.
  • This study demonstrates the first direct interaction between a regulatory protein and a small intestinal OATP.

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