Institute of Animal Sex and Development, Zhejiang Wanli University, Ningbo, 315100, PR China; College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo, 315100, PR China.
College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo, 315100, PR China; College of Fisheries and Life Sciences, Shanghai Ocean University, Shanghai, 201306, PR China.
Dev Biol. 2022 Dec;492:101-110. doi: 10.1016/j.ydbio.2022.10.001. Epub 2022 Oct 8.
The forkhead transcription factor Foxl2 plays a major role in ovarian development and function in mice and fish, and acts as a female sex-determining gene in goat. Its functional role in the sex determination and gonadal differentiation has not yet been investigated in reptiles. Here, we characterized Foxl2 gene in Chinese soft-shelled turtle Pelodiscus sinensis, exhibiting ZZ/ZW sex chromosomes. Foxl2 exhibited a female-specific embryonic expression pattern throughout the critical sex determination periods in P. sinensis. The expression of Foxl2 was induced at early stage in ZZ embryonic gonads that were feminized by estrogen treatment. Most importantly, Foxl2 knockdown in ZW embryos by RNA interference resulted in female-to-male sex reversal, characterized by obvious masculinization of gonads, significant up-regulation of testicular markers Dmrt1 and Sox9, and remarkable down-regulation of ovarian regulator Cyp19a1. Conversely, gain-of-function study showed that overexpression of Foxl2 in ZZ embryos led to largely feminized genetic males, production of Cyp19a1, and a decline in Dmrt1 and Sox9. These findings demonstrate that Foxl2 is both necessary and sufficient to initiate ovarian differentiation in P. sinensis, thereby acting as a key upstream regulator of the female pathway in a reptilian species.
叉头框转录因子 Foxl2 在小鼠和鱼类的卵巢发育和功能中发挥着重要作用，并且在山羊中作为雌性性别决定基因发挥作用。然而，其在爬行动物性别决定和性腺分化中的功能作用尚未得到研究。在这里，我们对具有 ZZ/ZW 性染色体的中华鳖 Pelodiscus sinensis 的 Foxl2 基因进行了表征。Foxl2 在 P. sinensis 的关键性别决定时期表现出雌性特异性的胚胎表达模式。Foxl2 在 ZZ 胚胎的早期阶段表达，而雌激素处理会使 ZZ 胚胎的性腺雌性化。最重要的是，通过 RNA 干扰在 ZW 胚胎中敲低 Foxl2 导致雌性到雄性的性别反转，其特征为性腺明显的男性化、睾丸标记物 Dmrt1 和 Sox9 的显著上调以及卵巢调节剂 Cyp19a1 的显著下调。相反，功能获得研究表明，Foxl2 在 ZZ 胚胎中的过表达导致遗传雄性的大部分雌性化，产生 Cyp19a1，并降低 Dmrt1 和 Sox9。这些发现表明，Foxl2 对于 P. sinensis 的卵巢分化是必要且充分的，因此在爬行动物物种中充当雌性途径的关键上游调节剂。
