Differential regulation of the luteinizing hormone genes in teleosts and tetrapods due to their distinct genomic environments - Insights into gonadotropin beta subunit evolution
Differential regulation of the luteinizing hormone genes in teleosts and tetrapods due to their distinct genomic environments - Insights into gonadotropin beta subunit evolution
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DOI：
10.1016/j.ygcen.2011.05.015
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发表时间：
2011-09-01
影响因子：
2.7
通讯作者：
Oka, Yoshitaka
中科院分区：
文献类型：
--
作者：
Kanda, Shinji;Okubo, Kataaki;Oka, Yoshitaka
垂体促性腺激素，卵泡刺激素（FSH）和黄体生成素（LH），是控制脊椎动物生殖所必需的。虽然这两种激素的分子结构从硬骨鱼到哺乳动物都很保守，但一些研究报告了硬骨鱼和四足动物之间基因表达的调控机制的差异。在本研究中，我们研究了脊椎动物促性腺激素基因位点的分子进化，发现在硬骨鱼类fshb和四足动物fshb和lhb位点之间存在同线保守性。然而，硬骨鱼lhb基因座与四足动物lhb或硬骨鱼fshb没有同线同源性;这一事实表明，在第三轮全基因组复制后，由于基因组进化速度加快，lhb基因座发生了广泛的全基因组重排。随后，我们证明了通过双标记原位杂交使用硬骨鱼青，在硬骨鱼的fshb和lhb基因表达在完全独立的细胞群在垂体，这是不同的四足动物。此外，在卵巢切除和类固醇治疗青鳉的表达分析表明，在繁殖条件下，青鳉LH β的表达下调卵巢切除和恢复与性腺类固醇治疗，这一结果也是完全相反的哺乳动物，类固醇对LH β的表达有负反馈作用。我们认为，硬骨鱼类和哺乳动物之间在lhb基因的细胞表达模式和动态表达变化的差异是在硬骨鱼类进化早期发生的lhb基因的基因组环境的剧烈变化的结果。(C)2011 Elsevier Inc. All rights reserved.
The pituitary gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), are essential for the control of vertebrate reproduction. Although the molecular structures of these two hormones are well conserved from teleosts to mammals, some studies report differences in their regulatory mechanisms of gene expression between teleosts and tetrapods. In the present study, we examined the molecular evolution of the gonadotropin gene loci in vertebrates and found that there is a syntenic conservation among the teleost fshb and tetrapod fshb and lhb loci. However, the teleost lhb locus has no syntenic homology to either tetrapod lhb or teleost fshb; this fact suggests that an extensive genome-wide rearrangement of the lhb locus, caused by an accelerated genome evolution speed after the third round of genome-wide duplication, occurred in the teleost lineage. We subsequently demonstrated by double labeling in situ hybridization using a teleost medaka that the fshb and lhb genes in teleosts are expressed in completely separate cellular populations in the pituitary, which is different in tetrapods. Furthermore, the expression analysis in ovariectomized and steroid-treated medaka revealed that, under breeding conditions, the expression of the medaka LH beta was down-regulated by ovariectomy and recovered by treatment with gonadal steroids; this result is also completely opposite in mammals, where the steroids have negative-feedback effects on LH beta expression. We suggest that these differences between teleosts and mammals in the cellular expression pattern and dynamic expressional changes of the lhb gene are the result of the drastic changes in the genomic environment of the lhb gene that occurred early in teleost evolution. (C) 2011 Elsevier Inc. All rights reserved.