Sodium iodide symporter (NIS) gene expression in human placenta

The placenta must allow the passage of iodide from the maternal to the feta l circulation for synthesis of thyroxine by the fetal thyroid. The thyroid sodium iodide symporter (NIS) was cloned in 1996 and, although widely distr ibuted among epithelial tissues, early studies failed to detect it in place nta. We demonstrated NIS mRNA in human placenta and in the human choriocarc inoma cell line, JAr. NIS protein was localized to trophoblasts, with a ten dency to apical distribution, in sections of human placenta immunostained w ith a monoclonal antibody against hNIS. We conclude that NIS is expressed i n placenta and may mediate placental iodide transport. (C) 2001 Harcourt Pu blishers Ltd.