Molecular and evolutionary characterization of the GnRH-II gene in the chicken:: Distinctive genomic organization, expression pattern, and precursor sequence
Molecular and evolutionary characterization of the GnRH-II gene in the chicken:: Distinctive genomic organization, expression pattern, and precursor sequence
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DOI：
10.1016/j.gene.2005.10.004
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发表时间：
2006-03-01
期刊：
影响因子：
3.5
通讯作者：
Park, MK
中科院分区：
文献类型：
--
作者：
Ikemoto, T;Park, MK
在GnRH(促性腺激素释放激素)的所有结构变体中，GnRH-II在颌骨脊椎动物中普遍存在，并在没有任何序列替换的情况下唯一保守。我们之前的研究发现，基于爬行动物和哺乳动物GNR-H-II的比较，GnRH-II前体序列在真兽类的谱系中已经变得不同。为了阐明GnRH-H在整个羊膜动物中的分子进化，我们首次从鸡中鉴定了禽类GnRH-II基因，鸡是最初发现GnRH-II肽的物种。鸡GnRH-H的基因排列与哺乳动物相似，但有一个MRPS26基因与鸡GnRH-II下游部分重叠。GnRH-II/MRPS26基因座至少产生了5种不同类型的转录本，其中3种可能产生功能性GnRH-II十肽。序列比较表明，该鸡的前GnRH-II多肽在长度和相似性上与其他物种有很大的不同。这一结果有力地表明，在羊膜动物进化过程中，进化保守的GnRH-II的前体序列发生了相当大的变化。也有人认为，在鸡身上看到的序列差异可能是独立于哺乳动物谱系发生的。(C)2005 Elsevier B.V.保留所有权利。
Of all the structural variants of GnRH (gonadotropin-releasing hormone), GnRH-II has been found to be universally present in and uniquely conserved among jawed vertebrates without any sequence substitutions. Our previous study found that the GnRH-II precursor sequences have become divergent in the lineage of eutherian mammals, based on a comparison between reptilian and mammalian GnR-H-II. To elucidate the molecular evolution of GnRH-H throughout amniotes, we have performed the first identification of the avian GnRH-II cDNA/gene from the chicken, the species used for the initial discovery of GnRH-II peptide. Gene arrangement around the GnRH-H in the chicken was similar to that in mammals; however, a gene MRPS26 was partly overlapped with the downstream part of the GnRH-II in the chicken. It was identified that the GnRH-II/MRPS26 locus generated at least five distinct types of transcripts with different expression patterns and three of them may produce functional GnRH-II decapeptide. Sequence comparison revealed that the prepro-GnRH-II polypeptide of the chicken was substantially different from those of other species regarding the length and similarity. The present results strongly indicated that considerable variations were generated in the precursor sequence of the evolutionarily conserved GnRH-II during amniote evolution. It was also suggested that the sequence divergence seen in the chicken may have occurred independently of that in the mammalian lineage. (c) 2005 Elsevier B.V. All rights reserved.