Zhang Zhiwei, Zhu Bo, Ge Wei
School of Life Sciences (Z.Z., B.Z., W.G.), The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; and Faculty of Health Sciences (Z.Z., W.G.), University of Macau, Taipa, Macau, China.
Mol Endocrinol. 2015 Jan;29(1):76-98. doi: 10.1210/me.2014-1256.
Vertebrate reproduction is controlled by two gonadotropins (FSH and LH) from the pituitary. Despite numerous studies on FSH and LH in fish species, their functions in reproduction still remain poorly defined. This is partly due to the lack of powerful genetic approaches for functional studies in adult fish. This situation is now changing with the emergence of genome-editing technologies, especially Transcription Activator-Like Effector Nuclease (TALEN) and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR). In this study, we deleted the hormone-specific β-genes of both FSH and LH in the zebrafish using TALEN. This was followed by a phenotype analysis for key reproductive events, including gonadal differentiation, puberty onset, gametogenesis, final maturation, and fertility. FSH-deficient zebrafish (fshb(-/-)) were surprisingly fertile in both sexes; however, the development of both the ovary and testis was significantly delayed. In contrast, LH-deficient zebrafish (lhb(-/-)) showed normal gonadal growth, but the females failed to spawn and were therefore infertile. Using previtellogenic follicles as the marker, we observed a significant delay of puberty onset in the fshb mutant but not the lhb mutant females. Interestingly, FSH seemed to play a role in maintaining the female status because we repeatedly observed sexual reversal in the fshb mutant. Neither the fshb nor lhb mutation alone seemed to affect gonadal differentiation; however, the double mutation of the two genes led to all males, although the development of the testis was significantly delayed. In summary, our data confirmed some well-known functions of FSH and LH in fish while also providing evidence for novel functions, which would be difficult to reveal using traditional biochemical and physiological approaches.
脊椎动物的繁殖受垂体分泌的两种促性腺激素（促卵泡激素和促黄体生成素）控制。尽管对鱼类中的促卵泡激素和促黄体生成素进行了大量研究，但它们在繁殖中的功能仍不清楚。部分原因是缺乏用于成年鱼功能研究的强大遗传方法。随着基因组编辑技术的出现，尤其是转录激活样效应核酸酶（TALEN）和规律成簇间隔短回文重复序列（CRISPR）的出现，这种情况正在改变。在本研究中，我们使用TALEN在斑马鱼中删除了促卵泡激素和促黄体生成素的激素特异性β基因。随后对关键生殖事件进行了表型分析，包括性腺分化、青春期开始、配子发生、最终成熟和生育能力。促卵泡激素缺陷型斑马鱼（fshb(-/-)）两性均出人意料地具有生育能力；然而，卵巢和睾丸的发育均显著延迟。相比之下，促黄体生成素缺陷型斑马鱼（lhb(-/-)）性腺生长正常，但雌性无法产卵，因此不育。以卵黄生成前卵泡为标志物，我们观察到fshb突变体雌性青春期开始显著延迟，而lhb突变体雌性则没有。有趣的是，促卵泡激素似乎在维持雌性状态中发挥作用，因为我们在fshb突变体中反复观察到性逆转。单独的fshb或lhb突变似乎都不影响性腺分化；然而，这两个基因的双突变导致全为雄性，尽管睾丸发育显著延迟。总之，我们的数据证实了促卵泡激素和促黄体生成素在鱼类中的一些已知功能，同时也为新功能提供了证据，而这些新功能用传统的生化和生理学方法很难揭示。
