Lumayno Sanny David Pacheco, Ohga Hirofumi, Selvaraj Sethu, Nyuji Mitsuo, Yamaguchi Akihiko, Matsuyama Michiya
Laboratory of Marine Biology, Kyushu University, Fukuoka 812-8581, Japan.
Laboratory of Marine Biology, Kyushu University, Fukuoka 812-8581, Japan.
Gen Comp Endocrinol. 2017 Jun 1;247:143-151. doi: 10.1016/j.ygcen.2017.01.027. Epub 2017 Jan 30.
The gonadotropin-releasing hormone (GnRH) is essential during pubertal onset, for its regulation of the synthesis and release of pituitary gonadotropins. Its action is mediated by GnRH receptors (GnRHRs) in the pituitary gonadotrophs. Our previous study demonstrated that the chub mackerel brain expresses three GnRH forms (gnrh1, gnrh2, and gnrh3), and that only GnRH1 neurons innervate anterior pituitary regions. Furthermore, chub mackerel gnrh1 mRNA exhibited a significant increase at pubertal onset. The present study aimed to isolate the functional GnRHR form involved in chub mackerel puberty. The open reading frame of our cloned receptor encodes 428 amino acids and contains seven transmembrane domains. Phylogenetic analysis also indicated clustering with other teleost-type IIB GnRHRs, mainly those involved in reproduction. Reporter gene assay results showed that all four synthetic peptides (GnRH1, GnRH2, GnRH3, and GnRH analogue) bind to the cloned receptor. Three deduced GnRH ligands stimulated luteinizing hormone (LH) release from cultured pituitary cells in vitro. Receptor gene expression was mainly detected in the pituitary and showed an increasing trend in the developing gonadal stages of both sexes during the pubertal process; this process was synchronous with previous studies of follicle-stimulating hormone beta (fshβ) and lhβ gene expression in chub mackerel. These results suggest that the cloned receptor is likely involved in the regulation of pubertal onset in this species. Therefore, we have designated the receptor cmGnRHR1.
促性腺激素释放激素（GnRH）在青春期启动过程中至关重要，因为它可调节垂体促性腺激素的合成与释放。其作用是通过垂体促性腺细胞中的GnRH受体（GnRHRs）介导的。我们之前的研究表明，鲐鱼大脑表达三种GnRH形式（gnrh1、gnrh2和gnrh3），且只有GnRH1神经元支配垂体前叶区域。此外，鲐鱼gnrh1 mRNA在青春期启动时显著增加。本研究旨在分离参与鲐鱼青春期的功能性GnRHR形式。我们克隆的受体开放阅读框编码428个氨基酸，并包含七个跨膜结构域。系统发育分析还表明，它与其他硬骨鱼IIB型GnRHRs聚类，主要是那些参与繁殖的受体。报告基因检测结果表明，所有四种合成肽（GnRH1、GnRH2、GnRH3和GnRH类似物）均与克隆的受体结合。三种推导的GnRH配体在体外刺激培养的垂体细胞释放促黄体生成素（LH）。受体基因表达主要在垂体中检测到，并且在青春期两性性腺发育阶段呈上升趋势；这一过程与之前对鲐鱼促卵泡激素β（fshβ）和促黄体生成素β（lhβ）基因表达的研究同步。这些结果表明，克隆的受体可能参与了该物种青春期启动的调节。因此，我们将该受体命名为cmGnRHR1。
