Bevelander Gideon S, Hang Xiaoming, Abbink Wout, Spanings Tom, Canario Adelino V M, Flik Gert
Department of Animal Physiology, Faculty of Science, Radboud University Nijmegen, Toernooiveld 1, ED Nijmegen, The Netherlands.
Gen Comp Endocrinol. 2006 Nov;149(2):159-65. doi: 10.1016/j.ygcen.2006.05.016. Epub 2006 Jul 12.
In fish, vitellogenin is an important nutritional precursor protein produced solely in the liver and released into the blood where it binds calcium. In the gilthead sea bream (Sparus auratus) 17beta-Estradiol (E2) plays an important role in the synthesis of vitellogenin, but also the pituitary hormones prolactin (PRL) and growth hormone (GH) can stimulate vitellogenin induction in fish. Considering the emerging involvement of PTHrP in fish calcium metabolism and the importance of calcium regulation in reproduction, we investigated the possible role of PTHrP in vitellogenesis. E2-naïve and E2-primed sea bream hepatocytes were used in an in vitro primary hepatocyte culture and stimulated with a recombinant sea bream PTHrP (sbPTHrP) to establish the contribution of sbPTHrP alone or in combination with E2 to the regulation of hepatic vitellogenin synthesis. Hepatocytes stimulated solely with sbPTHrP were not affected in their vitellogenesis. However, in hepatocytes stimulated with E2 in combination with sbPTHrP a higher vitellogenin production was seen than with E2 alone. It is concluded that sbPTHrP has a potentiating effect on estradiol stimulation of vitellogenin production by sea bream hepatocytes. The sea bream provides a unique model where vitellogenesis regulation can be studied on E2-naïve liver cells, both in vivo and in vitro.
在鱼类中，卵黄蛋白原是一种重要的营养前体蛋白，仅在肝脏中产生并释放到血液中，在血液中它会结合钙。在金头鲷（Sparus auratus）中，17β-雌二醇（E2）在卵黄蛋白原的合成中起重要作用，但垂体激素催乳素（PRL）和生长激素（GH）也能刺激鱼类的卵黄蛋白原诱导。考虑到甲状旁腺激素相关蛋白（PTHrP）在鱼类钙代谢中的新作用以及钙调节在繁殖中的重要性，我们研究了PTHrP在卵黄生成中的可能作用。使用未接触过E2和已用E2预处理的金头鲷肝细胞进行体外原代肝细胞培养，并用重组金头鲷PTHrP（sbPTHrP）刺激，以确定sbPTHrP单独或与E2联合对肝脏卵黄蛋白原合成调节的作用。仅用sbPTHrP刺激的肝细胞的卵黄生成未受影响。然而，在用E2联合sbPTHrP刺激的肝细胞中，卵黄蛋白原的产量比单独用E2刺激时更高。得出的结论是，sbPTHrP对雌二醇刺激金头鲷肝细胞产生卵黄蛋白原有增强作用。金头鲷提供了一个独特的模型，在这个模型中，可以在体内和体外对未接触过E2的肝细胞进行卵黄生成调节的研究。
