Iodine, sodium-iodine symporter and thyroid diseases
Turowska, M.D.; Rogowski, F.; Jurgilewicz, D.H.
Przeglad Lekarski 57(6): 353-355
2000
ISSN/ISBN: 0033-2240 PMID: 11107872 Document Number: 518949
The Na+/I- symporter (NIS) is the plasma membrane protein that catalyzes the accumulation of iodine into thyroid cells against an electrochemical gradient. This iodine uptake is the first step in thyroid hormone biogenesis which is stimulated by TSH--the main hormone regulating thyroid--specific functions. This process requires energy from the action of Na+/K+ ATP-ase. TSH upregulates NIS gene expression, and this induction can be modulated by cytokines. Analysis of the distribution of NIS mRNA demonstrated variable levels of NIS transcription in different tissue samples. Increased NIS expression has been found in autonomous adenoma and Graves' disease, decreased levels of NIS protein and/or mRNA NIS were observed in Hashimoto's disease, scintigraphically cold nodules and most thyroid cancers. NIS mutation has been found in congenital hypothyroidism. Potential defects in the NIS gene are currently under investigation in various thyroid diseases.