Laboratory of Integrative Neuroendocrinology, Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, S7N 5B4, Saskatchewan, Canada.
Sci Rep. 2020 Apr 14;10(1):6264. doi: 10.1038/s41598-020-63226-x.
Phoenixin-20 (PNX-20) is a bioactive peptide with hormone-like actions in vertebrates. In mammals, PNX stimulates hypothalamo-pituitary-gonadal hormones and regulate reproductive processes. Our immunohisto/cytochemical studies show PNX-like and the putative PNX receptor, SREB3-like immunoreactivity in the gonads of zebrafish, and in zebrafish liver (ZFL) cells. Intraperitoneal injection of zebrafish PNX-20 upregulates mRNAs encoding both salmon gonadotropin-releasing hormone (GnRH), and chicken GnRH-II and kisspeptin and its receptor in zebrafish hypothalamus. Similarly, luteinizing hormone receptor mRNA expression in the testis, follicle-stimulating hormone receptor in the ovary, and the kisspeptin system were upregulated in the gonads of PNX-20 injected fish. We also observed the upregulation of genes involved in the sex steroidogenic pathway (cyp11a1, cyp17a1, 17βhsd, cyp19a1a) in the gonads of PNX-20 administered fish. PNX-20 upregulates the expression of vitellogenin isoforms and estrogen receptor (esr2a and 2b) mRNAs in ZFL cells in vitro. Meanwhile, siRNA-mediated knockdown of PNX-20 resulted in the downregulation of all vitellogenin transcripts, further suggesting its possible role in vitellogenesis. PNX-20 treatment resulted in a significant increase in germinal vesicle breakdown in zebrafish follicles in vitro. Collectively, these results provide strong evidence for PNX-20 effects on the HPG axis and liver to promote reproduction in zebrafish.
凤凰素-20（PNX-20）是一种具有脊椎动物激素样作用的生物活性肽。在哺乳动物中，PNX 刺激下丘脑-垂体-性腺激素并调节生殖过程。我们的免疫组织化学/细胞化学研究表明，PNX 样和推定的 PNX 受体 SREB3 样免疫反应性存在于斑马鱼的性腺中，以及斑马鱼肝（ZFL）细胞中。腹腔注射斑马鱼 PNX-20 可上调编码鲑鱼促性腺激素释放激素（GnRH）、鸡 GnRH-II 和 kisspeptin 及其受体的 mRNA，并在斑马鱼下丘脑上调。同样，在注射 PNX-20 的鱼的睾丸中，促黄体生成素受体 mRNA 的表达、卵巢中的卵泡刺激素受体以及 kisspeptin 系统在性腺中上调。我们还观察到参与性类固醇合成途径的基因（cyp11a1、cyp17a1、17βhsd、cyp19a1a）在注射 PNX-20 的鱼的性腺中上调。PNX-20 在体外上调 ZFL 细胞中卵黄蛋白原同工型和雌激素受体（esr2a 和 2b）mRNA 的表达。同时，siRNA 介导的 PNX-20 敲低导致所有卵黄蛋白原转录本的下调，进一步表明其在卵黄发生中的可能作用。PNX-20 处理导致斑马鱼卵泡中的生殖泡破裂显著增加。总之，这些结果为 PNX-20 对 HPG 轴和肝脏的影响提供了有力证据，以促进斑马鱼的繁殖。
