Department of Biological Science, Faculty of Science, Shizuoka University, Shizuoka 422-8529, Japan.
Gen Comp Endocrinol. 2021 May 1;305:113735. doi: 10.1016/j.ygcen.2021.113735. Epub 2021 Feb 4.
In plasma, thyroid hormone (TH) is bound to several TH distributor proteins (THDPs), constituting a TH delivery/distribution network. Extensive studies of THDPs from tetrapods has proposed an evolutionary scenario concerning structural and functional changes in THDPs, especially for transthyretin (TTR). When assessing, in an evolutionary context, the roles of THDPs as a component constituting part of the vertebrate thyroid system, the data from fish THDPs are critical. In this review the phylogenetic distributions, spatiotemporal expression patterns and binding properties of THDPs in fish are described, and the question of whether the evolutionary hypotheses proposed in tetrapod THDPs can be applied to fish THDPs is assessed. The phylogenetic distributions of THDPs are highly variable among fish groups. Analysis in this review reveals that the evolutionary hypotheses proposed in tetrapod THDPs cannot be applied to fish THDPs, and that the role of plasma lipoproteins as THDPs grows in importance in fish groups. In primitive fish, zinc is an import factor in TH binding to TTR, and high zinc content may facilitate the acquisition of high TH binding activity during the early evolution of TTR. Finally, the possible roles of THDPs in the vertebrate thyroid system are discussed.
在血浆中，甲状腺激素 (TH) 与几种 TH 分布蛋白 (THDP) 结合，构成了 TH 传递/分布网络。对四足动物 THDP 的广泛研究提出了一个关于 THDP 结构和功能变化的进化情景，特别是对转甲状腺素蛋白 (TTR)。在评估 THDP 作为构成脊椎动物甲状腺系统一部分的组成部分的作用时，从鱼类 THDP 获得的数据至关重要。在这篇综述中，描述了鱼类 THDP 的系统发育分布、时空表达模式和结合特性，并评估了在四足动物 THDP 中提出的进化假设是否可以应用于鱼类 THDP。THDP 的系统发育分布在鱼类群体中差异很大。本综述中的分析表明，在四足动物 THDP 中提出的进化假设不能应用于鱼类 THDP，并且在鱼类群体中，血浆脂蛋白作为 THDP 的作用变得越来越重要。在原始鱼类中，锌是 TH 与 TTR 结合的重要因素，高锌含量可能有助于在 TTR 的早期进化过程中获得高 TH 结合活性。最后，讨论了 THDP 在脊椎动物甲状腺系统中的可能作用。
