TY - JOUR AU - Köhrle, Josef AB - Abstract The thyroid gland has an exceptionally high selenium content, even during selenium deficiency. At least 11 selenoproteins are expressed, which may be involved in the protection of the gland against the high amounts of H 2 O 2 produced during thyroid hormone biosynthesis. As determined here by in situ hybridization and Northern blotting experiments, glutathione peroxidases (GPx) 1 and 4 and selenoprotein P were moderately expressed, occurring selectively in the follicular cells and in leukocytes of germinal follicles of thyroids affected by Hashimoto's thyroiditis. Selenoprotein 15 was only marginally expressed and distributed over all cell types. GPx3 mRNA was exclusively localized to the thyrocytes, showed the highest expression levels and was down-regulated in 5 of 6 thyroid cancer samples as compared to matched normal controls. GPx3 could be extracted from thyroidal colloid by incubation with 0.5% sodium dodecyl sulfate indicating that this enzyme is (i) secreted into the follicular lumen and (ii) loosely attached to the colloidal thyroglobulin. These findings are consistent with a role of selenoproteins in the protection of the thyroid from possible damage by H 2 O 2 . Particularly, GPx3 might use excess H 2 O 2 and catalyze the polymerization of thyroglobulin to the highly cross-linked storage form present in the colloid. TI - Selenoproteins of the thyroid gland: expression, localization and possible function of glutathione peroxidase 3 JF - Biological Chemistry DO - 10.1515/BC.2007.122 DA - 2007-10-01 UR - https://www.deepdyve.com/lp/de-gruyter/selenoproteins-of-the-thyroid-gland-expression-localization-and-CIYqQfPy6U SP - 1053 VL - 388 IS - 10 DP - DeepDyve ER -