Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, School of Medicine, Université Libre de Bruxelles, 1070 Brussels, Belgium.
J Clin Endocrinol Metab. 2010 Jan;95(1):375-82. doi: 10.1210/jc.2009-1727. Epub 2009 Dec 1.
Thyroid hormone synthesis requires H(2)O(2) produced by dual oxidases (Duoxes) and thyroperoxidase (TPO). Defects in this system lead to congenital hypothyroidism. H(2)O(2) damage to the thyrocytes may be a cause of cancer.
The objective of the study was to investigate whether Duox and TPO, the H(2)O(2) producer and consumer, might constitute a complex in the plasma membrane of human thyroid cells, thus maximizing efficiency and minimizing leakage and damage.
The interaction between Duox and TPO was studied by coimmunoprecipitation and Western blotting of plasma membranes from incubated follicles prepared from freshly resected human thyroid tissue from patients undergoing thyroidectomy, and COS-7 cells transiently transfected with the entire Duoxes or truncated [amino (NH2) or carboxyl (COOH) terminal].
The following results were reached: 1) Duox and TPO from membranes are coprecipitated, 2) this association is up-regulated through the Gq-phospholipase C-Ca(2+)-protein kinase C pathway and down-regulated through the Gs-cAMP-protein kinase A pathway, 3) H(2)O(2) increases the association of Duox1 and Duox2 to TPO in cells and in membranes, and 4) truncated NH(2)- or COOH-terminal Duox1 and Duox2 proteins show different binding abilities with TPO.
Coimmunoprecipitations show that Duox and TPO locate closely in the plasma membranes of human thyrocytes, and this association can be modulated by H(2)O(2), optimizing working efficiency and minimizing H(2)O(2) spillage. This association could represent one part of a postulated pluriprotein complex involved in iodination. This suggests that defects in this association could impair thyroid hormone synthesis and lead to thyroid insufficiency and cell damage.
甲状腺激素的合成需要双氧化酶（Duoxes）和甲状腺过氧化物酶（TPO）产生的 H2O2。该系统的缺陷会导致先天性甲状腺功能减退。H2O2 对甲状腺细胞的损害可能是癌症的一个原因。
本研究旨在探讨双氧化酶和 TPO（H2O2 的产生者和消耗者）是否可能在人甲状腺细胞的质膜中构成复合物，从而最大限度地提高效率，减少泄漏和损伤。
通过对从接受甲状腺切除术的患者新切除的甲状腺组织制备的孵育滤泡中分离的质膜进行共免疫沉淀和 Western blot 分析，研究了 Duox 和 TPO 之间的相互作用，同时还分析了 COS-7 细胞中转染整个 Duox 或截断 [氨基（NH2）或羧基（COOH）末端] 的瞬时转染。
结果如下：1）质膜中的 Duox 和 TPO 被共沉淀；2）这种关联通过 Gq-磷脂酶 C-Ca（2+）-蛋白激酶 C 途径上调，通过 Gs-cAMP-蛋白激酶 A 途径下调；3）H2O2 增加了 Duox1 和 Duox2 与细胞和质膜中 TPO 的关联；4）截断的 NH2-或 COOH-末端 Duox1 和 Duox2 蛋白与 TPO 具有不同的结合能力。
共免疫沉淀表明，Duox 和 TPO 在人甲状腺细胞的质膜中紧密定位，这种关联可以通过 H2O2 进行调节，从而优化工作效率并最大程度地减少 H2O2 的泄漏。这种关联可能是参与碘化的假定多蛋白复合物的一部分。这表明这种关联的缺陷可能会损害甲状腺激素的合成，导致甲状腺功能不足和细胞损伤。
