Effects of thyroglobulin and pendrin on iodide flux through the thyrocyte

Iodide transport by thyrocytes involves porters on the apical and basal sur faces of the cell facing the follicular rumen and bloodstream, respectively . Recent work identifies pendrin as an apical porter and shows that follicu lar thyroglobulin is a transcriptional regulator of the gene encoding pendr in and other thyroid-restricted genes. For example, whereas follicular thyr oglobulin suppresses the gene expression and activity of the sodium iodide symporter (NIS), it increases pendrin gene expression. A potential new dyna mic for iodide flux and thyroid hormone formation in thyrocytes has thus em erged and is supported by in vivo data.