tHyroId aBnormaLIty and neuroLogIcaL deFIcIts reLated to mct8 Loss-oF-FunctIon mutatIons

In addition, a recent study by Di Cosmo et al suggested a putative role of MCT8 in thyroid hormone secretion. Thyroid hormones are released across the basolateral membrane of thyroid follicular cells, adjacent to the capillary bed. MCT8 immunohistochemical localization at the basolateral membrane of thyrocytes and the impairment in the efflux of T4 from the thyroid gland in MCT8KO mice implies that MCT8 mediates, at least in part, the transport of thyroid hormones from the thyrocytes into the bloodstream. Of the studied thyroid hormone transporters, MCT8 is the most abundantly expressed, followed by MCT10 and, to a lesser extent, the secondary TH transporters Lat1 and Lat2. According to Nishimura and Naito, MCT8 is abundantly expressed in the human thyroid gland and therefore the molecular mechanism regulating thyroid hormone secretion in mice could also exist in humans.