Thyroglobulin (Tg) is a large glycoprotein consisting of 2,768 amino acid residues and the precursor of thyroid hormones (THs). Since abnormalities in Tg function and expression may naturally affect thyroid function, there has been much interest in the mechanisms that regulate the expression and maturation of Tg. By contrast, Tg found in the blood, because of leakage from thyroid follicles, is used as a marker of thyroid goiters and inflammation. However, the precise structure and function of the huge Tg macromolecule are still unclear. Recently, it was shown that Tg at its physiological concentration in follicles dynamically regulates the expression of various thyroid-specific genes responsible for counteracting the effect of TSH. In addition, it was also shown that Tg induces thyroid cell proliferation. Thus, follicular Tg is now recognized as an autocrine negative-feedback regulator tightly controlling follicular function. In this review, we will briefly summarize recent advances of Tg function. Keywords: Thyroid; Thyroglobulin; Thyroid hormones; TSH
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