Functional Characterization of GH-Like Homolog in Amphioxus Reveals an Ancient Origin of GH/GH Receptor System
Functional Characterization of GH-Like Homolog in Amphioxus Reveals an Ancient Origin of GH/GH Receptor System
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DOI：
10.1210/en.2014-1377
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发表时间：
2014-12-01
期刊：
影响因子：
4.8
通讯作者：
Zhang, Shicui
中科院分区：
文献类型：
--
作者：
Li, Mengyang;Gao, Zhan;Zhang, Shicui
文昌鱼属于头索动物亚门，是现存最底层脊索动物的代表。尽管对文昌鱼的内分泌系统有很多研究，但没有证据表明垂体激素的存在。在这项研究中，我们清楚地证明了文昌鱼中存在一种功能性GH样激素，它能够结合纯化的GH受体，刺激IGF-I的表达，促进鱼类的生长速度，并挽救由于GH缺乏而导致的胚胎缺陷。我们还表明存在的GH/催乳素样结合蛋白含有整个激素结合结构域的GH/催乳素受体在文昌鱼，这是广泛表达的组织之间，并与GH样激素相互作用。从这些结果可以清楚地看出，GH/GH受体样系统存在于文昌鱼，因此，在所有类别的脊索动物。值得注意的是，生长激素样激素似乎是文昌鱼中脊椎动物垂体激素家族的唯一成员，这表明该激素是起源于脊索动物垂体激素家族分子进化的祖先肽。这些数据表明文昌鱼体内已经出现了类似脊椎动物的神经内分泌轴结构，为脊椎动物下丘脑-垂体系统的形成奠定了基础。
Amphioxus belongs to the subphylum cephalochordata, an extant representative of the most basal chordates. Despite many studies on the endocrine system of amphioxus, no evidence showed the presence of pituitary hormones. In this study, we clearly demonstrated the existence of a functional GH-like hormone in amphioxus, which is able to bind purified GH receptors, stimulate IGF-I expression, promote growth rate of fish, and rescue embryonic defects caused by a shortage of GH. We also showed the presence of a GH/prolactin-like-binding protein containing the entire hormone binding domain of GH/prolactin receptors in amphioxus, which is widely expressed among tissues, and interacts with the GH-like hormone. It is clear from these results that the GH/GH receptor-like system is present in amphioxus and, hence, in all classes of chordates. Notably, the GH-like hormone appears to be the only member of the vertebrate pituitary hormones family in amphioxus, suggesting that the hormone is the ancestral peptide that originated first in the molecular evolution of the pituitary hormones family in chordates. These data collectively suggest that a vertebrate-like neuroendocrine axis setting has already emerged in amphioxus, which lays a foundation for subsequent formation of hypothalamic-pituitary system in vertebrates.