Department of Animal Sciences, The Robert H. Smith Faculty of Agriculture, Food, and Environment, Hebrew University of Jerusalem, Rehovot 76100, Israel.
Department of Animal Sciences, The Robert H. Smith Faculty of Agriculture, Food, and Environment, Hebrew University of Jerusalem, Rehovot 76100, Israel; MIGAL - Galilee Technology Center, P.O. Box 831, Kiryat Shmona 10200, Israel; School of Science and Technology, Tel-Hai Academic College, Galilee, Israel.
Gen Comp Endocrinol. 2021 Feb 1;302:113691. doi: 10.1016/j.ygcen.2020.113691. Epub 2020 Dec 7.
Sturgeons belong to a subclass of fishes that derived from ray-finned fish ancestors preceding the emergence of teleosts. The Russian sturgeon (Acipenser gueldenstaedtii) is a late-maturing fish with the females reaching puberty under aquaculture conditions at 6-10 years of age. Since kisspeptin has been shown to be a key hormone involved in regulation of major reproductive processes of many vertebrate species, this study was conducted to better understand the kisspeptin receptor (KissR) in sturgeon. In this study we have cloned Russian sturgeon KissR1 from brain mRNA and observed the ontogeny of rsKissR1 mRNA expression in ovarian follicles. Multiple sequence alignment of KissR1, KissR4, and their orthologs revealed that the Russian sturgeon (rs) KissR1 sequence shares 64%-77% identity with elephant shark, coelacanth, and gar and 44-58% identity with tetrapod and teleost KissR1 sequences, while KissR4 seemed to share <65% identity to eel KissR2 and ~57% identity to Perciformes and Cypriniformes. Further rsKissR4 showed <97% identity to reed fish KissR4, <63% with Squamata (Reptiles) and gar KissR4. A phylogenetic analysis revealed that rsKissR1 is more closely related to coelacanth and gar KissR1 than teleost, while rsKissR4 was part of the KissR4 clade and shared higher similarity with Actinopterygiian sequences. We have further predicted homology models for both rsKiss receptors and performed in-silico analyses of their binding to a kiss-10 peptide. Both sturgeon and zebrafish Kiss1 and Kiss2 activated rsKissR1 via both PKC/Ca2+ and PKA/cAMP signal-transduction pathways, while rsKissR2 was found to be less effective and was not activated by stKiss peptides. Ovarian rsKissR transcript levels for 10 fishes were determined by real-time PCR and significantly increased concomitantly with oogenesis, where the highest level of expression was evident in black follicles. These data suggest that extra-neuronal expression of the kisspeptin receptor may be involved in sturgeon reproduction in a manner dependent on reproductive development.
鲟鱼属于硬骨鱼纲的一个亚纲，起源于比硬骨鱼更早出现的软骨硬鳞鱼类。俄罗斯鲟（Acipenser gueldenstaedtii）是一种成熟较晚的鱼类，在水产养殖条件下，雌性达到性成熟的年龄为 6-10 岁。由于 kisspeptin 已被证明是许多脊椎动物主要生殖过程调节的关键激素，因此本研究旨在更好地了解鲟鱼的 kisspeptin 受体（KissR）。本研究从脑 mRNA 中克隆了俄罗斯鲟 KissR1，并观察了 rsKissR1mRNA 在卵巢滤泡中的个体发育表达。KissR1、KissR4 及其同源物的多重序列比对表明，俄罗斯鲟（rs）KissR1 序列与象鲨、腔棘鱼和雀鳝的同源性为 64%-77%，与四足动物和硬骨鱼的同源性为 44-58%，而 KissR4 与鳗鱼 KissR2 的同源性似乎<65%，与鲈形目和鲤形目鱼类的同源性约为 57%。此外，rsKissR4 与 reed 鱼 KissR4 的同源性<97%，与 Squamata（爬行动物）和雀鳝 KissR4 的同源性<63%。系统发育分析表明，rsKissR1 与腔棘鱼和雀鳝 KissR1 的亲缘关系比硬骨鱼更密切，而 rsKissR4 属于 KissR4 分支，与 Actinopterygiian 序列的相似度更高。我们进一步预测了两种 rsKiss 受体的同源模型，并对它们与 kiss-10 肽的结合进行了计算机模拟分析。鲟鱼和斑马鱼的 Kiss1 和 Kiss2 均通过 PKC/Ca2+和 PKA/cAMP 信号转导途径激活 rsKissR1，而 rsKissR2 的效果较差，并且不受 stKiss 肽的激活。通过实时 PCR 测定了 10 种鱼类卵巢中的 rsKissR 转录水平，结果表明，在卵巢发生过程中，rsKissR 转录水平显著升高，其中在黑滤泡中表达水平最高。这些数据表明，kisspeptin 受体的神经外表达可能参与了鲟鱼生殖的方式取决于生殖发育。
