Evolution of receptors for growth hormone and somatolactin in fish and land vertebrates: Lessons from the lungfish and sturgeon orthologues
Evolution of receptors for growth hormone and somatolactin in fish and land vertebrates: Lessons from the lungfish and sturgeon orthologues
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DOI：
10.1007/s00239-007-9035-7
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发表时间：
2007-10-01
影响因子：
3.9
通讯作者：
Meyer, Axel
中科院分区：
文献类型：
--
作者：
Fukamachi, Shoji;Meyer, Axel
生长激素（GH）和生长激素（SL）是脊椎动物的两种同源激素，控制着脊椎动物的几个重要生理过程。关于GH及其受体（GHR）的知识在过去几十年中已经积累。然而，对SL及其受体（SLR）的了解要少得多。SL仅在鱼类（包括肺鱼）中发现，这表明它存在于脊椎动物的共同祖先中，但在肺鱼分支后在导致陆地脊椎动物的谱系中继发丢失。SLR被认为是通过鱼类特异性基因组复制（FSGD）获得的GHR的复制拷贝。这种情况（即，在脊椎动物祖先中存在SL而不是SLR）是有趣的但有争议的。在这项研究中，我们首先通过同线分析评估了这种情况的可能性，发现GHR和SLR的基因座位于同线基因组位置，而GH和SL的基因座则不在同线基因组位置。接下来，我们克隆了肺鱼和鲟鱼的GHR，它们具有SL但没有经历FSGD（即，他们不应该拥有SLR）。它们在GHR/SLR基因树中的系统发育位置进一步支持了GHR-SLR重复的鱼类特异性情景。有趣的是，它们的序列与硬骨鱼SLR和爬行动物/两栖动物GHR的相似性比与哺乳动物、鸟类和硬骨鱼的GHR的相似性更大。在这些结果的基础上，我们讨论了在FSGD期间SLR进化之前，GHR的硬骨鱼特异性拷贝作为SLR和SL的祖先受体的命名的有效性。
Two cognate hormones, growth hormone (GH) and somatolactin (SL), control several important physiological processes in vertebrates. Knowledge about GH and its receptor (GHR) has accumulated over the last decades. However, much less is known about SL and its receptor (SLR). SL is found only in fish (including lungfish), suggesting that it was present in the common ancestor of vertebrates, but was lost secondarily in the lineage leading to land vertebrates after the lungfish branched off. SLR was suggested to be a duplicated copy of GHR acquired only in teleosts via the fish-specific genome duplication (FSGD). This scenario (i.e., the existence of SL but not SLR in the vertebrate ancestors) is intriguing but contested. In this study, we first evaluated the plausibility of this scenario through synteny analyses and found that the loci for GHR and SLR are located in syntenic genomic positions, whereas the loci for GH and SL are not. Next, we cloned GHRs of lungfish and sturgeon, which possess SL but did not undergo the FSGD (i.e., they should not possess SLR). Their phylogenetic positions in the GHR/SLR gene tree further support the fish-specific scenario for the GHR-SLR duplication. Interestingly, their sequences share greater similarity with teleost SLRs and reptilian/amphibian GHRs than with the GHRs of mammals, birds, and teleosts. On the basis of these results, we discuss the validity of the nomenclature of the teleost-specific copy of GHR as SLR and an ancestral receptor(s) for SL before the evolution of SLR during the FSGD.