Anti-TG monoclonal antibody

Terminal thyroid gland differentiation - the last developmental step needed to enable thyroid hormone (T4) synthesis - involves profound structural and biochemical changes in the thyroid follicular cells (TFCs). We aimed to develop an ex vivo thyroid model of embryonic mouse thyroid that would replicate the in vivo TFC differentiation program. E13.5 thyroid explants were cultured ex vivo in chemically defined medium for 7 days. Immunostaining and qPCR of thyroid explants showed thyroglobulin production onset, follicle formation, and T4 synthesis onset in 1-, 3-, and 5-day-old cultures, respectively. Differentiation was maintained and follicular growth continued throughout the 7-day culture period. Pharmacological approaches to culture inhibition were performed successfully in the ex vivo thyroids. Our robust and well described ex vivo thyroid culture model replicates the sequence of thyroid differentiation to T4 synthesis seen in vivo. This model can be used to test the effects of pharmacological inhibitors on thyroid hormone production.

Background: Thyroid hormone (TH) synthesis is essential for the control of development, growth, and metabolism in vertebrates and depends on a sufficient dietary iodine intake. Importantly, both iodine deficiency and iodine excess (IE) impair TH synthesis, causing serious health problems especially during fetal/neonatal development. While it is known that IE disrupts thyroid function by inhibiting thyroid gene expression, its effects on thyroid development are less clear. Accordingly, this study sought to investigate the effects of IE during the embryonic development/differentiation of endoderm and the thyroid gland. Methods: We used the murine embryonic stem (ES) cell model of in vitro directed differentiation to assess the impact of IE on the generation of endoderm and thyroid cells. Additionally, we subjected endoderm and thyroid explants obtained during early gestation to IE and evaluated gene and protein expression of endodermal markers in both models. Results: ES cells were successfully differentiated into endoderm cells and, subsequently, into thyrocytes expressing the specific thyroid markers Tshr, Slc5a5, Tpo, and Tg. IE exposure decreased the messenger RNA (mRNA) levels of the main endoderm markers Afp, Crcx4, Foxa1, Foxa2, and Sox17 in both ES cell-derived endoderm cells and embryonic explants. Interestingly, IE also decreased the expression of the main thyroid markers in ES cell-derived thyrocytes and thyroid explants. Finally, we demonstrate that DNA methyltransferase expression was increased by exposure to IE, and this was accompanied by hypermethylation and hypoacetylation of histone H3, pointing to an association between the gene repression triggered by IE and the observed epigenetic changes. Conclusions: These data establish that IE treatment is deleterious for embryonic endoderm and thyroid gene expression.