Lazcano Iván, Orozco Aurea
Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Boulevard Juriquilla 3001, Querétaro, Querétaro 76230, Mexico.
Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Boulevard Juriquilla 3001, Querétaro, Querétaro 76230, Mexico.
Gen Comp Endocrinol. 2018 Sep 1;265:128-132. doi: 10.1016/j.ygcen.2018.03.022. Epub 2018 Mar 21.
Teleosts are the most numerous class of living vertebrates. They exhibit great diversity in terms of morphology, developmental strategies, ecology and adaptation. In spite of this diversity, teleosts conserve similarities at molecular, cellular and endocrine levels. In the context of thyroidal systems, and as in the rest of vertebrates, thyroid hormones in fish regulate development, growth and metabolism by actively entering the nucleus and interacting with thyroid hormone receptors, the final sensors of this endocrine signal, to regulate gene expression. In general terms, vertebrates express the functional thyroid hormone receptors alpha and beta, encoded by two distinct genes (thra and thrb, respectively). However, different species of teleosts express thyroid hormone receptor isoforms with particular structural characteristics that confer singular functional traits to these receptors. For example, teleosts contain two thra genes and in some species also two thrb; some of the expressed isoforms can bind alternative ligands. Also, some identified isoforms contain deletions or large insertions that have not been described in other vertebrates and that have not yet been functionally characterized. As in amphibians, the regulation of some of these teleost isoforms coincides with the climax of metamorphosis and/or life transitions during development and growth. In this review, we aimed to gain further insights into thyroid signaling from a comparative perspective by proposing a systematic nomenclature for teleost thyroid hormone receptor isoforms and summarize their particular functional features when the information was available.
硬骨鱼是现存脊椎动物中数量最多的一类。它们在形态、发育策略、生态和适应性方面表现出极大的多样性。尽管存在这种多样性，但硬骨鱼在分子、细胞和内分泌水平上仍保持着相似性。在甲状腺系统方面，与其他脊椎动物一样，鱼类中的甲状腺激素通过主动进入细胞核并与甲状腺激素受体相互作用来调节发育、生长和代谢，甲状腺激素受体是这种内分泌信号的最终传感器，用于调节基因表达。一般来说，脊椎动物表达由两个不同基因（分别为thra和thrb）编码的功能性甲状腺激素受体α和β。然而，不同种类的硬骨鱼表达具有特定结构特征的甲状腺激素受体亚型，这些特征赋予了这些受体独特的功能特性。例如，硬骨鱼含有两个thra基因，在某些物种中还含有两个thrb；一些表达的亚型可以结合替代配体。此外，一些已鉴定的亚型含有在其他脊椎动物中未描述且尚未进行功能表征的缺失或大的插入片段。与两栖动物一样，这些硬骨鱼亚型中的一些调节与发育和生长过程中的变态高潮和/或生命转变相吻合。在本综述中，我们旨在通过为硬骨鱼甲状腺激素受体亚型提出系统的命名法，并在有信息可用时总结它们的特定功能特征，从比较的角度进一步深入了解甲状腺信号传导。
