Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City, Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Chongqing Municipality for Aquatic Economic Animal Resources Conservation and Germplasm Creation, School of Life Sciences, Southwest University, Chongqing 400715, China.
Genes (Basel). 2024 Sep 23;15(9):1238. doi: 10.3390/genes15091238.
17α-Methyltestosterone (MT) is a widely used androgen for all-male fish production in aquaculture. However, the molecular mechanism underlying MT-induced masculinization remains unclear. In this study, we aim to identify the key gene responsible for MT-induced masculinization using the Nile tilapia () , , and mutants, which exhibit male-to-female sex reversal. Nile tilapia fry from these three mutant lines were treated with 50 μg/g MT from 5 to 30 days after hatching (dah). The results showed that and mutants, but not mutants, were masculinized by the MT treatment. Gonadal transcriptome analysis revealed that genes involved in steroidogenesis and germ cell development in MT-treated mutants exhibited a similar expression pattern to that of the wild type (WT) XX. In addition, the mutants cannot be masculinized by co-treatment with MT and the aromatase inhibitor fadrozole. The MT treatment completely blocked early steroidogenic enzyme (Star2, Cyp17a2, and Cyp19a1a) expression independent of , , and . A luciferase analysis showed that MT directly suppressed basal and Sf-1-activated promoter activity through and in cultured HEK293 cells. Furthermore, MT treatment inhibited germ cell proliferation in and mutants but not in mutants. Consistently, expression was induced in MT-treated WT XX, -, and - mutants. Taken together, these results suggest that is indispensable for MT-induced masculinization in Nile tilapia and that MT functions by inhibiting early steroid synthesis and activating to promote testis development.
17α-甲基睾丸酮（MT）是水产养殖中广泛用于全雄鱼类生产的雄激素。然而，MT 诱导雄性化的分子机制尚不清楚。在本研究中，我们旨在使用尼罗罗非鱼（）、和突变体来鉴定与 MT 诱导雄性化相关的关键基因，这些突变体表现出雄性到雌性的性反转。来自这三个突变系的尼罗罗非鱼鱼苗在孵化后 5 至 30 天（dah）用 50μg/g MT 处理。结果表明，和突变体而非突变体被 MT 处理雄性化。性腺转录组分析显示，参与类固醇生成和生殖细胞发育的基因在 MT 处理的突变体中表现出与野生型（WT）XX 相似的表达模式。此外，突变体不能通过与 MT 和芳香酶抑制剂 fadrozole 共同处理而雄性化。MT 处理完全阻断了早期类固醇生成酶（Star2、Cyp17a2 和 Cyp19a1a）的表达，而与、和无关。荧光素酶分析显示，MT 通过和在培养的 HEK293 细胞中直接抑制基础和 Sf-1 激活的启动子活性。此外，MT 处理抑制了和突变体中的生殖细胞增殖，但在突变体中没有。一致地，在 MT 处理的 WT XX、-、-突变体中诱导了表达。总之，这些结果表明在尼罗罗非鱼中是 MT 诱导雄性化所必需的，MT 通过抑制早期类固醇合成和激活来促进睾丸发育。
