title: Pendrin: the thyrocyte apical membrane iodide transporter?
abstract: In the thyroid, the transport of iodide from the extracellular space to the follicular lumen requires two steps: the transport in the cell at the basal side and in the lumen at the apical side. The first step is mediated by the Na(+)/I(-) symporter (NIS). In most reviews and textbooks, the second step is presented as mediated by pendrin. In this review, we analyze this assumption. There are several arguments supporting the concept that indeed pendrin plays an important role in thyroid physiology. However, biochemical, clinical and histological data on the thyroid of a patient with Pendred syndrome do not suggest an essential role in iodide transport, which is corroborated by the lack of a thyroid phenotype in pendrin knockout mice. Experiments in vivo and in vitro on polarized and unpolarized cells show that iodide is transported transport of iodide at the apex of the thyroid cell. Moreover, ectopic expression of pendrin in transfected non-thyroid cells is capable of mediating iodide efflux. It is concluded that pendrin may participate in the iodide efflux into thyroid lumen but not as the unique transporter. Moreover, another role of pendrin in mediating Cl(-)/HCO(3)(-) exchange and controlling luminal pH is suggested.
authors: Molecular Biology of the Gene Laboratory and Center of Microscopy and Molecular Imaging, University of Brussels, IBMM, Campus Gosselies, Brussels, Belgium.
authors: Laure
authors: L
authors: Twyffels
authors: Claude
authors: C
authors: Massart
authors: Philippe E
authors: PE
authors: Golstein
authors: Eric
authors: E
authors: Raspe
authors: Jacqueline
authors: J
authors: Van Sande
authors: Jacques E
authors: JE
authors: Dumont
authors: Renaud
authors: R
authors: Beauwens
authors: Véronique
authors: V
authors: Kruys
mesh_terms: D000818:Animals; D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism*; D006044:Goiter, Nodular / Q000473:pathology; D006319:Hearing Loss, Sensorineural / Q000473:pathology; D007454:Iodides / Q000378:metabolism*; D017136:Ion Transport; D023421:Models, Animal; D000076988:Sulfate Transporters; D013961:Thyroid Gland / Q000166:cytology* / Q000378:metabolism*
chemical_list: D027321:Anion Transport Proteins; D007454:Iodides; C494849:Slc26a4 protein, mouse; D000076988:Sulfate Transporters