Thyroid and Hydrogen Peroxide / 한양의대학술지

ABSTRACT

The thyroid gland produces high concentrations of hydrogen peroxide (H2O2) which is used for the biosynthesis of the thyroid hormones, triiodothyronine and thyroxine. The most important step in thyroid hormone synthesis is oxidation and organification of iodide, which itself is a very potent oxidant. To oxidize iodide, thyrocytes generate high intracellular concentrations of H2O2 using the NADPH-dependent dual oxidase enzymes (DUOX) and remove used H2O2 by various well-characterized antioxidant systems, such as those involving glutathione peroxidases and peroxiredoxins. Although thyrocytes have very intricate and efficient systems to regulate H2O2 generation and removal, leakage of H2O2 may be inevitable because of the high intracellular concentrations of H2O2 in thyrocytes. Leakage of the highly reactive oxidant H2O2 is likely to cause the damage to various intracellular proteins and DNA that has been demonstrated to be a causative factor in the induction of various diseases, such as thyroid cancer, chronic thyroiditis and hyperthyroidism. Therefore, ongoing investigation of the systems regulating H2O2 production and elimination in thyrocytesis essential for understanding the regulation and process of thyroid hormone synthesis and also for elucidating pathogenetic mechanisms underlying various autoimmune thyroid diseases and the initiation and promotion of thyroid cancers.