Three gonadotropin-releasing hormone genes in one organism suggest novel roles for an ancient peptide.
Three gonadotropin-releasing hormone genes in one organism suggest novel roles for an ancient peptide.
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一个生物体中的三个促性腺激素释放激素基因表明了一种古老肽的新作用。
DOI：
10.1073/pnas.92.18.8363
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发表时间：
1995
影响因子：
11.1
通讯作者：
Fernald,RD
中科院分区：
文献类型：
--
作者：
White,SA;Kasten,TL;Bond,CT;Adelman,JP;Fernald,RD
促性腺激素释放激素（GnRH）是已知的，并以其在脊椎动物生殖中的重要作用命名。这种十肽从下丘脑神经元的释放控制垂体促性腺激素水平，进而调节性腺状态。GnRH的重要性被其在脊椎动物类群中的广泛表达和保守性所强调：五种氨基酸在所有九种已知形式中是不变的，而另外两种仅显示保守的变化。在大多数真兽目哺乳动物中，只有一种形式，在下丘脑中表达，被认为存在，尽管在最近的报告中，发育中的灵长类动物的抗体染色表明还有另一种形式。相反，在许多非哺乳类脊椎动物中已经报道了多种GnRH形式和表达位点。然而，基于免疫学鉴别的证据并不总是与基因表达分析一致，因为不同基因编码的GnRH形式可能无法通过抗体可靠区分。在这里，我们报告了三种不同的GnRH基因在硬骨鱼脑中的表达，包括编码一种新的GnRH前激素原的序列。使用原位杂交，我们发现，这种形式只在神经元，项目的垂体和表现出变化的索马大小取决于社会和生殖状态。另外两个GnRH基因在其他不同的细胞群中表达。所有三个基因共享编码由GnRH和GnRH相关肽组成的多肽的基序。而GnRH部分是高度保守的，GnRH相关肽不是，反映了不同的选择压力对不同的基因部分。在非下丘脑区域表达的GnRH形式可用于协调动物的生殖活动。
Gonadotropin-releasing hormone (GnRH) is known and named for its essential role in vertebrate reproduction. Release of this decapeptide from neurons in the hypothalamus controls pituitary gonadotropin levels which, in turn, regulate gonadal state. The importance of GnRH is underscored by its widespread expression and conservation across vertebrate taxa: five amino acids are invariant in all nine known forms, whereas two others show only conservative changes. In most eutherian mammals, only one form, expressed in the hypothalamus, is thought to exist, although in a recent report, antibody staining in developing primates suggests an additional form. In contrast, multiple GnRH forms and expression loci have been reported in many non-mammalian vertebrates. However, evidence based on immunological discrimination does not always agree with analysis of gene expression, since GnRH forms encoded by different genes may not be reliably distinguished by antibodies. Here we report the expression of three distinct GnRH genes in a teleost fish brain, including the sequence encoding a novel GnRH preprohormone. Using in situ hybridization, we show that this form is found only in neurons that project to the pituitary and exhibit changes in soma size depending on social and reproductive state. The other two GnRH genes are expressed in other, distinct cell populations. All three genes share the motif of encoding a polypeptide consisting of GnRH and a GnRH-associated peptide. Whereas the GnRH moiety is highly conserved, the GnRH-associated peptides are not, reflecting differential selective pressure on different parts of the gene. GnRH forms expressed in nonhypothalamic regions may serve to coordinate reproductive activities of the animal.