Thyroid Specific Gene Expression
The biosynthesis of thyroid hormones requires the iodination and coupling of two tyrosine residues. During evolution specialized cells within the thyroid gland have developed to accomplish this task. The follicular cells of the thyroid gland are arranged in a characteristic tridimensional structure which consists of a sphere of follicular cells surrounding a lumen. Iodine is transported from the bloodstream into the follicular cells by a thyroid specific iodine channel, and subsequently reaches the lumen of the follicle. Two further thyroid specific functions are present in the follicle to assist hormone synthesis: a thyroid specific peroxidase (TPO) and thyroglobulin (Tg). The peroxidase has two functions: it catalyzes the incorporation of iodine onto some of the tyrosyl residues of the thyroglobulin molecule and it is required for the coupling of a subset of the iodinated residues to form the hormones. Upon interaction of Thyroid Stimulating Hormone (TSH) with its receptor the modified thyroglobulin is reabsorbed from the follicular lumen, then it is degraded within the follicular cells and free hormone is released in the bloodstream1.
KeywordsThyroid Stimulate Hormone Follicular Cell Thyroid Cell Chloramphenicol Acetyl Transferase Thyroglobulin Gene
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- 1.A. Taurog, Hormone synthesis: thyroid iodine metabolism, in: “Werner’s The Thyroid,” S. H. Ingbar, and L. E Bravermann, eds., J.B. Lippincott Company, Philadelphia (1986).Google Scholar
- 2.H. Edelhoc, and J. Robbins, Thyroglobulin: Chemistry and Biosynthesis, in: “Werner’s The Thyroid,” S. H. Ingbar, and L. E. Braverman, eds., J.B. Lippincott Company, Philadelphia (1986).Google Scholar
- 10.M. D. Walker, T. Edlund, A. M. Boulet, and W. J. Rutter, Cell-specific expression controlled by the 5’-flanking region of insulin and chymotrypsin genes, Nature. 306: 557 (1983).Google Scholar
- 12.F. S. Ambesi-Impiombato, and H. G. Coon, Thyroid cells in culture, Int. Rev. Cytol. 12, Suppl. 10: 163 (1979).Google Scholar
- 18.D. Civitareale, L. Ghibelli, and R. Di Lauro, Partial purification of a thyroid specific protein recognizing the thyroglobulin promoter., in: “Molecular biology approaches to thyroid research,” Loos, U.,Wartofsky, L. eds, Georg Thieme Verlag Stuttgart-New York (1987).Google Scholar
- 22.G. Colletta, A. Pinto, P. P. Di Fiore, A. Fusco, M. Ferrentino, V. E. Avvedimento, N. Tsuchida, and G. Vecchio, Dissociation between transformed and differentiated phenotype in rat thyroid epithelial cells after transformation with a temperature sensitive mutant of the Kirsten murine sarcoma virus, Mol. Cell. Biol. 3: 2099 (1983).PubMedGoogle Scholar
- 26.S. Kimura, Y. Hong, T. Kotani, S. Ohtaki, and F. Kikkawa, Structure of the human peroxidase gene: comparison and relationhsip to the human myeloperoxidase gene, Biochemistry. in press: (1989).Google Scholar
- 30.P. Santisteban, L. D. Kohn, and R. Di Lauro, Thyroglobulin gene expression is regulated by insulin and isulin-like growth factor I, as well as thyrotropin, in FRTL-5 thyroid cells, J Biol. Chem. 262:4048 (1987).Google Scholar
- 33.L. Remy, M. Michel-Bechet, A. M. Athouel-Haon, S. Magre, C. Cataldo, and A. Jost, Development of the thyroid gland in the rat fetus in vivo. An ultrastructural and radioautographic study., Anat. Microsc. Morphol. Exp. 69: 91 (1980).Google Scholar