Oreochromis mossambicus (tilapia) Corticotropin‐Releasing Hormone: cDNA Sequence and Bioactivity
Oreochromis mossambicus (tilapia) Corticotropin‐Releasing Hormone: cDNA Sequence and Bioactivity
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DOI：
10.1046/j.1365-2826.2000.00434.x
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发表时间：
2000-02
影响因子：
3.2
通讯作者：
F. H. V. van Enckevort;P. Pepels;J. Leunissen;G. Martens;S. W. Wendelaar Bonga;P. Balm
中科院分区：
文献类型：
--
作者：
F. H. V. van Enckevort;P. Pepels;J. Leunissen;G. Martens;S. W. Wendelaar Bonga;P. Balm
尽管下丘脑促肾上腺皮质激素释放激素（CRH）参与所有脊椎动物群体的应激反应，但只有少数关于这种神经内分泌肽的研究涉及非哺乳动物神经内分泌系统。我们确定了硬骨鱼 Oreochromis mossambicus（罗非鱼）的 CRH 前体 cDNA 序列，并在同源硬骨鱼生物测定中研究了 CRH 肽的生物效力。使用简并引物和特异性引物的聚合酶链反应 (PCR) 产生了罗非鱼 CRH cDNA 片段。用罗非鱼CRH PCR产物筛选罗非鱼下丘脑cDNA文库，获得全长CRH cDNA（988个核苷酸）。前体序列（167 个氨基酸）包含信号肽、CRH 肽和所有脊椎动物 CRH 前体中保守的基序。罗非鱼 CRH (41 个氨基酸) 与其他脊椎动物的 CRH 具有 63% 至 80% 的氨基酸序列同一性，而与尾加压素 I/urocortin 谱系成员的同一性程度则相当低。在系统发育树中，基于目前已知的所有完整 CRH 肽前体的比对，三种硬骨鱼 CRH 前体（罗非鱼、红鲑、Oncorhynchus nerka、白吸盘、Catostomus commersoni）形成了一个与两栖动物和哺乳动物前体不同的单系群。尽管罗非鱼和大鼠 CRH 的主要结构存在差异，但罗非鱼和大鼠 CRH 的最大有效浓度在体外刺激罗非鱼垂体释放促肾上腺皮质激素 (ACTH) 和 α-MSH 方面具有同等效力。罗非鱼和鲑鱼的 CRH 序列表明，直系同源脊椎动物 CRH 结构，特别是硬骨鱼 CRH 之间存在比以前认识到的更多变异。结构差异是否反映了该肽在应激反应中的不同作用机制仍有待研究。
Although hypothalamic corticotropin‐releasing hormone (CRH) is involved in the stress response in all vertebrate groups, only a limited number of studies on this neuroendocrine peptide deals with non‐mammalian neuroendocrine systems. We determined the cDNA sequence of the CRH precursor of the teleost Oreochromis mossambicus (tilapia) and studied the biological potency of the CRH peptide in a homologous teleost bioassay. Polymerase chain reaction (PCR) with degenerate and specific primers yielded fragments of tilapia CRH cDNA. Full‐length CRH cDNA (988 nucleotides) was obtained by screening a tilapia hypothalamus cDNA library with the tilapia CRH PCR products. The precursor sequence (167 amino acids) contains a signal peptide, the CRH peptide and a motif conserved among all vertebrate CRH precursors. Tilapia CRH (41 aa) displays between 63% and 80% amino acid sequence identity to CRH from other vertebrates, whereas the degree of identity to members of the urotensin I/urocortin lineage is considerably lower. In a phylogenetic tree, based on alignment of all full CRH peptide precursors presently known, the three teleost CRH precursors (tilapia; sockeye salmon, Oncorhynchus nerka; white sucker, Catostomus commersoni) form a monophyletic group distinct from amphibian and mammalian precursors. Despite the differences between the primary structures of tilapia and rat CRH, maximally effective concentrations of tilapia and rat CRH were equally potent in stimulating adrenocorticotropic hormone (ACTH) and α‐MSH release by tilapia pituitaries in vitro. The tilapia and salmon CRH sequences show that more variation exists between orthologous vertebrate CRH structures, and teleost CRHs in particular than previously recognized. Whether the structural differences reflect different mechanisms of action of this peptide in the stress response remains to be investigated.