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Physiological activity and tissue distribution of a perchlorate‐sensitive iodide transport protein from anuran amphibians
Author(s) -
Carr Deborah L.,
Carr James A.,
Pressley Thomas A.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1396-c
Subject(s) - sodium iodide symporter , symporter , iodide , xenopus , thyroid , biology , metamorphosis , endocrinology , amphibian , medicine , perchlorate , transporter , bullfrog , cotransporter , biochemistry , chemistry , sodium , larva , gene , ecology , ion , organic chemistry
Iodide is a critical trace nutrient in the synthesis of thyroid hormone (TH). Environmental contaminants that competitively inhibit the sodium/iodide symporter (NIS), such as ammonium perchlorate and sodium chlorate, may pose a significant threat to developing amphibians, which require TH for metamorphosis and reproductive development. Unfortunately, little is known about the structure and regulation of the frog NIS. We transiently transfected cultured monkey kidney cells with a putative iodide transporter cloned from African clawed frogs ( Xenopus laevis ), the X. laevis solute carrier family 5 (sodium iodide symporter) member 5 (SLC5A5), and measured radiolabeled 125 I uptake in vitro. Cells expressing the SLC5A5 clone had significantly greater 125 I than sham‐transfected control cells. Uptake of 125 I in SCL5A5‐transfected cells was significantly inhibited in the presence of perchlorate. Amplification of RNA sequences from amphibian tissues indicates that the SCL5A5 is expressed in thyroid gland, stomach and kidney of larval bullfrogs ( Rana catesbeiana ) and larval X. laevis , tissues known to transport iodide. We conclude that the X. laevis SLC5A5 transporter is a perchlorate‐sensitive iodide transporter that is expressed in thyroid and extrathyroid tissues in frogs. This research lays the groundwork for future studies examining the physiology and toxicology of iodide transport in amphibian thyroid and non‐thyroid epithelia. [Supported by NIH grant RR‐19799.]