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[Enzymes involved in thyroid iodide organification]
Mário Vaisman1, Doris Rosenthal, Denise P Carvalho
1Serviço de Endocrinologia, Hospital Universitário Clementino Fraga Filho, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ.
Arquivos Brasileiros De Endocrinologia E Metabologia
|December 22, 2004
Summary
Thyroid hormone production relies on iodide uptake via the sodium-iodide symporter (NIS) and its incorporation into thyroglobulin (Tg). Hydrogen peroxide generation by thyroid NADPH oxidase (ThOx) is the rate-limiting step in this process.
Area of Science:
- Endocrinology
- Molecular Biology
- Cell Biology
Context:
- Thyroid hormone biosynthesis is a complex process crucial for metabolism and development.
- Key proteins involved include thyroglobulin (Tg), sodium-iodide symporter (NIS), pendrin (PDS), and thyroperoxidase (TPO).
- Thyroid hormone production is tightly regulated by various factors, including iodide availability and cellular signaling.
Purpose:
- To elucidate the intricate steps of thyroid hormone biosynthesis, focusing on iodide uptake and organification.
- To identify the rate-limiting step in thyroid hormone production under conditions of iodine sufficiency.
- To understand the role of thyroid NADPH oxidase (ThOx) in hydrogen peroxide generation for thyroid hormone synthesis.
Summary:
- Iodide uptake is mediated by the sodium-iodide symporter (NIS) and pendrin (PDS), followed by incorporation into thyroglobulin (Tg).
- Thyroperoxidase (TPO) catalyzes iodide oxidation and organification using hydrogen peroxide (H2O2) as a cofactor.
- Thyroid NADPH oxidase (ThOx) generates H2O2, and its activity is stimulated by thyrotropin and inhibited by iodide, making H2O2 generation the rate-limiting step in iodine-sufficient conditions.
Impact:
- Provides a detailed molecular understanding of thyroid hormone biosynthesis.
- Highlights the critical role of hydrogen peroxide generation in regulating thyroid hormone production.
- Offers insights into potential targets for therapeutic interventions related to thyroid disorders.