Muséum National d'Histoire Naturelle, Unité Mixte de Recherche Biologie des Organismes et Ecosystèmes Aquatiques (UMR BOREA), Biology of Aquatic Organisms and Ecosystems, Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), Sorbonne Université, Paris, France.
Université Le Havre Normandie - Stress Environnementaux et Biosurveillance des milieux aquatiques UMR-I 02SEBIO -FR CNRS 3730 SCALE, Le Havre, France.
Front Endocrinol (Lausanne). 2022 Jul 22;13:937218. doi: 10.3389/fendo.2022.937218. eCollection 2022.
Corticotropin-releasing hormone (CRH) was discovered for its role as a brain neurohormone controlling the corticotropic axis in vertebrates. An additional gene, , paralog of (), and likely resulting from the second round (2R) of vertebrate whole genome duplication (WGD), was identified in a holocephalan chondrichthyan, in basal mammals, various sauropsids and a non-teleost actinopterygian holostean. It was suggested that has been recurrently lost in some vertebrate groups including teleosts. We further investigated the fate of and in vertebrates with a special focus on teleosts. Phylogenetic and synteny analyses showed the presence of duplicated paralogs, and , in most teleosts, resulting from the teleost-specific WGD (3R). is conserved in all teleosts studied, while has been lost independently in some species. Additional paralogs are present in carps and salmonids, resulting from specific WGD in these lineages. We identified gene in additional vertebrate groups such as chondrichthyan elasmobranchs, sarcopterygians including dipnoans and amphibians, and basal actinoperygians, Polypteridae and Chondrostei. We also revealed the presence of in teleosts, including elopomorphs, osteoglossomorphs, clupeiforms, and ostariophysians, while it would have been lost in Euteleostei along with some other groups. To get some insights on the functional evolution of the paralogs, we compared their primary and 3D structure, and by qPCR their tissue distribution, in two representative species, the European eel, which possesses three paralogs (, , ), and the Atlantic salmon, which possesses four paralogs of the crh1-type. All peptides conserved the structural characteristics of human CRH. Eel and both salmon genes were mainly expressed in the brain, supporting the major role of paralogs in controlling the corticotropic axis in teleosts. In contrast, paralogs were mainly expressed in peripheral tissues such as muscle and heart, in eel and salmon, reflecting a striking subfunctionalization between and paralogs. Eel was weakly expressed in the brain and peripheral tissues. These results revisit the repertoire of in teleosts and highlight functional divergences that may have contributed to the differential conservation of various paralogs in teleosts.
促肾上腺皮质激素释放激素 (CRH) 最初被发现是作为一种脑神经激素，控制脊椎动物的促皮质激素轴。在全基因组重复（WGD）的第二轮（2R）中，发现了另一个基因 ，它是 () 的旁系同源基因，存在于软骨鱼纲的全头鱼、基底哺乳动物、各种蜥形类和非硬骨鱼纲的硬骨鱼中。有人认为， 已在包括硬骨鱼在内的一些脊椎动物群体中反复丢失。我们进一步研究了 基因在脊椎动物中的命运，特别关注硬骨鱼。系统发育和基因同线性分析显示，大多数硬骨鱼中存在重复的 旁系同源基因 、 和 ，这是硬骨鱼特有的 WGD（3R）的结果。在所研究的所有硬骨鱼中都保守存在 ，而 在一些物种中独立丢失。鲤鱼和鲑鱼目中存在额外的 旁系同源基因，这是这些谱系中特定 WGD 的结果。我们在软骨鱼纲的鲨鱼和板鳃鱼类、肉鳍鱼类包括肺鱼和两栖动物以及基底辐鳍鱼类、多鳍鱼目和软骨硬鳞鱼类等其他脊椎动物群体中鉴定出 基因。我们还揭示了 基因在硬骨鱼中的存在，包括鳗鲡目、骨舌鱼目、鲱形目和鲈形目，而它在真骨总目鱼类中与其他一些群体一起丢失。为了深入了解 基因的功能进化，我们比较了两种代表物种，即欧洲鳗鲡，它拥有三个 旁系同源基因（、和），以及大西洋鲑，它拥有四个 crh1 型的 基因的一级和 3D 结构，并用 qPCR 检测了它们的组织分布。所有肽都保留了人类 CRH 的结构特征。鳗鲡的 和两种鲑鱼的 基因主要在大脑中表达，这支持了 基因在硬骨鱼中控制促皮质激素轴的主要作用。相比之下， 旁系同源基因主要在鳗鲡和鲑鱼的肌肉和心脏等外周组织中表达，反映了 基因和 基因之间的显著亚功能化。鳗鲡的 基因在大脑和外周组织中的表达较弱。这些结果重新审视了硬骨鱼中 基因的基因库，并强调了功能上的差异，这可能导致不同 基因在硬骨鱼中的不同程度的保存。
