The role of StAR2 gene in testicular differentiation and spermatogenesis in Nile tilapia (Oreochromis niloticus)
The role of StAR2 gene in testicular differentiation and spermatogenesis in Nile tilapia (Oreochromis niloticus)
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StAR2基因在尼罗罗非鱼（Oreochromis niloticus）睾丸分化和精子发生中的作用
DOI：
10.1016/j.jsbmb.2021.105974
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发表时间：
2021-08-24
影响因子：
4.1
通讯作者：
Zhou, Linyan
中科院分区：
文献类型：
--
作者：
Li, Lu;Wu, You;Zhou, Linyan
性类固醇激素在硬骨鱼性别分化和性腺发育中起着重要作用。类固醇生成急性调节蛋白（星星）是类固醇生成的第一个限速因子，负责将胆固醇（类固醇生成的底物）从线粒体外膜转运到内膜。有趣的是，两个星星基因（命名为StAR 1和StAR 2）已从非哺乳类脊椎动物中分离出来。为了研究StAR 2基因在尼罗罗非鱼性腺分化和育性中的功能，我们在尼罗罗非鱼（Oreochromis niloticus）中构建了StAR 2纯合突变体。雄性罗非鱼StAR 2基因敲除阻碍了减数分裂启动，与孵化后90天（dah）减数分裂相关基因vasa、sycp 3和dazl的表达下调有关。与此同时，在90 dah时，在StAR 2- /- XY鱼中cyp 11b 2表达和血清11-KT产生显著下降。120-300 dah，精子发生逐渐恢复，vasa、sycp 3和dazl在StAR 2-/- XY精巢中的表达也逐渐恢复。而300日龄时，StAR 2-/- XY鱼睾丸中的生精小叶排列紊乱。在300 dah时，StAR 2-/- XY鱼睾丸中Leydig细胞的数量和下游类固醇生成酶cyp 11 a1、3 beta-HSD-I、3 beta-HSD-II、cyp 17 a1和cyp 17 a2的表达减少。血清睾酮和11-KT水平显着低于StAR 2-/- XY鱼比他们的对照。此外，显着升高ar，fsh和lh的表达在StAR 2缺陷XY鱼睾丸和垂体相比，控制XY鱼。在540 dah时，StAR 2-/- XY鱼的睾丸发生变性和生精细胞凋亡，但没有精子被挤出。综上所述，我们的研究结果表明，StAR 2通过调节罗非鱼雄激素的产生在睾丸发育、精子发生和精子形成中发挥作用，但可能不是必需的，可以得到补偿。
Sex steroids play critical roles in sex differentiation and gonadal development in teleosts. Steroidogenic acute regulatory protein (StAR), transporting cholesterol (the substrate for steroidogenesis) from the outer mitochondrial membrane to the inner membrane, is the first rate-limiting factor of steroidogenesis. Interestingly, two StAR genes (named as StAR1 and StAR2) have been isolated from non-mammalian vertebrates. To characterize the functions of the novel StAR2 gene in the gonadal differentiation and fertility, we generated a StAR2 homozygous mutant line in Nile tilapia (Oreochromis niloticus). StAR2 gene knockout in male tilapia impeded meiotic initiation, associate with the down-regulation of meiosis related gene expressions of vasa, sycp3 and dazl at 90 days after hatching (dah). Meanwhile, cyp11b2 expression and serum 11-KT production significantly declined in StAR2- /- XY fish at 90 dah. From 120-300 dah, spermatogenesis gradually recovered, and so did the expressions of vasa, sycp3 and dazl in StAR2-/- XY fish testes. However, seminiferous lobules arranged disorderly in StAR2-/- XY fish testes at 300 dah. The number of Leydig cells and expressions of downstream steroidogenesis enzymes including cyp11a1, 3 beta-HSD-I, 3 beta-HSD-II, cyp17a1 and cyp17a2 decreased in StAR2-/- XY fish testes at 300 dah. Serum testosterone and 11-KT levels were significantly lower in StAR2-/- XY fish than that of their control counterparts. Furthermore, significantly elevated ar, fsh and lh expressions in StAR2-deficient XY fish testes and pituitaries were found when compared with the control XY fish. Testes degeneration and spermatogenic cell apoptosis were observed, while no sperm were squeezed out in StAR2-/- XY fish testes at 540 dah. Taken together, our results suggest that StAR2 has a role in testicular development, spermatogenesis and spermiation by regulating androgen production in tilapia, but may not be essential and could be compensated.