A second gene for gonadotropin-releasing hormone: cDNA and expression pattern in the brain.
A second gene for gonadotropin-releasing hormone: cDNA and expression pattern in the brain.
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促性腺激素释放激素的第二个基因：cDNA 和大脑中的表达模式。
DOI：
10.1073/pnas.91.4.1423
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发表时间：
1994
影响因子：
11.1
通讯作者：
Adelman,JP
中科院分区：
文献类型：
--
作者：
White,SA;Bond,CT;Francis,RC;Kasten,TL;Fernald,RD;Adelman,JP
在脊椎动物中，促性腺激素释放激素（GnRH）十肽由下丘脑神经末梢分泌，通过控制垂体促性腺激素的合成和释放来调节生殖。在哺乳动物中仅发现一种GnRH肽，但有一种例外，尽管许多其他脊椎动物表达八种已知十肽形式中的一种以上，如脑中不同细胞群的免疫细胞化学标记所示。然而，这些GnRH形式之间的功能和进化关系都不清楚，因为只有一个preprohormone基因序列从任何物种已被报道。GnRH最普遍的替代形式是[His 5，Trp 7，Tyr 8]GnRH（也称为鸡-II），其在氨基酸5，7和8处与哺乳动物序列不同。这种肽已被证明具有最有效的释放激素活性，尽管免疫细胞化学染色表明它只在中脑合成。在这里，我们报告的基因的克隆和表达模式的前体，这种形式的硬骨鱼Haplochromis burtoni。这是第二个GnRH编码基因的特点，在这个物种。新发现的前激素原基因在两个方面与先前报道的不同。首先，原始基因只预测一个相关肽，而这个基因预测两个相关肽，两者似乎都是独特的。第二，[His 5，Trp 7，Tyr 8]GnRH的基因仅在中脑的一个细胞群中表达。与此相反，以前报道的基因仅在终末神经中表达。前激素原结构和定位之间的显著差异表明，编码两种已知GnRH形式的基因在H. burtoni并非来自最近的重复事件。有趣的是，迄今为止在该物种中发现的两种基因都不在从下丘脑到垂体的细胞中表达，这表明可能存在第三种编码GnRH的基因。
In vertebrates, the gonadotropin-releasing hormone (GnRH) decapeptide is secreted from hypothalamic nerve terminals to regulate reproduction via control of synthesis and release of pituitary gonadotropins. Only one GnRH peptide has been found in mammals, with one exception, although numerous other vertebrate species express more than one of the eight known decapeptide forms as shown by immunocytochemical labeling of distinct cell groups in the brain. However, neither the functional nor the evolutionary relationships among these GnRH forms are clear, because only one preprohormone gene sequence from any species has been reported. The most ubiquitous alternative form of GnRH is [His5,Trp7,Tyr8]GnRH (also referred to as chicken-II), which differs from the mammalian sequence at amino acids 5, 7, and 8. This peptide has been shown to have the most potent releasing-hormone activity, although immunocytochemical staining has suggested it is synthesized only in the mesencephalon. Here we report the cloning and expression pattern of the gene for the precursor of this form from the teleost fish Haplochromis burtoni. This is the second GnRH-encoding gene to be characterized in this species. The newly discovered preprohormone gene differs from that previously reported in two ways. First, whereas the original gene predicts only a single associated peptide, this one predicts two associated peptides, both of which appear to be unique. Second, the gene for [His5,Trp7,Tyr8]GnRH is expressed in only one cell group in the mesencephalon. In contrast, the previously reported gene is expressed only in the terminal nerve. The striking differences between the preprohormone structure and localization suggest that the genes coding for the two known GnRH forms in H. burtoni did not arise from a recent duplication event. Interestingly, neither of the two genes found to date in this species is expressed in cells which project from the hypothalamus to the pituitary, suggesting that yet a third gene coding for GnRH may exist.