High temperature induces cyp26b1 mRNA expression and delays meiotic initiation of germ cells by increasing cortisol levels during gonadal sex differentiation in Japanese flounder
High temperature induces cyp26b1 mRNA expression and delays meiotic initiation of germ cells by increasing cortisol levels during gonadal sex differentiation in Japanese flounder
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DOI：
10.1016/j.bbrc.2012.02.012
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发表时间：
2012-03-09
影响因子：
3.1
通讯作者：
Kitano, Takeshi
中科院分区：
文献类型：
--
作者：
Yamaguchi, Toshiya;Kitano, Takeshi
日本比目鱼（Paralichthys olivaceus）是一种具有XX/XY性别决定系统的硬骨鱼。在性别分化期分别在18 ℃或27 ℃下饲养，可以诱导XX比目鱼发育为表型雌性或雄性。因此，比目鱼为研究温度依赖性性别决定的分子机制提供了一个很好的模型。我们以前表明，皮质醇，在硬骨鱼的肾间细胞产生的主要糖皮质激素，直接抑制卵巢型芳香化酶（CYP 19 A1），负责在性腺中的雄激素转化为雌激素的类固醇生成酶的mRNA表达，导致女性到男性的性逆转。此外，皮质醇合成的抑制剂防止雄性化的XX比目鱼在27摄氏度，这表明高温的雄性化是由于抑制cyp 19 a1 mRNA的表达在比目鱼性腺性别分化的皮质醇水平升高。在本研究中，我们发现，在性腺性别分化过程中暴露于高温上调类维生素A降解酶（cyp 26 b1）的mRNA表达伴随着XX性腺的雄性化和延迟生殖细胞减数分裂的启动。我们还发现，皮质醇诱导cyp 26 b1 mRNA的表达和抑制特定的减数分裂标记联会复合体蛋白3（sycp 3）mRNA的表达在性腺的性分化过程中。总之，这些结果表明，暴露于高温诱导cyp 26 b1 mRNA的表达和延迟生殖细胞减数分裂的启动，通过提高皮质醇水平在性腺性别分化在日本比目鱼。(C)2012 Elsevier Inc. All rights reserved.
The Japanese flounder (Paralichthys olivaceus) is a teleost fish with an XX/XY sex determination system. XX flounder can be induced to develop into phenotypic females or males, by rearing them at 18 degrees C or 27 degrees C, respectively, during the sex differentiation period. Therefore, the flounder provides an excellent model to study the molecular mechanisms underlying temperature-dependent sex determination. We previously showed that cortisol, the major glucocorticoid produced by the interrenal cells in teleosts, causes female-to-male sex reversal by directly suppressing mRNA expression of ovary-type aromatase (cyp19a1), a steroidogenic enzyme responsible for the conversion of androgens to estrogens in the gonads. Furthermore, an inhibitor of cortisol synthesis prevented masculinization of XX flounder at 27 degrees C, suggesting that masculinization by high temperature is due to the suppression of cyp19a1 mRNA expression by elevated cortisol levels during gonadal sex differentiation in the flounder. In the present study, we found that exposure to high temperature during gonadal sex differentiation upregulates the mRNA expression of retinoid-degrading enzyme (cyp26b1) concomitantly with masculinization of XX gonads and delays meiotic initiation of germ cells. We also found that cortisol induces cyp26b1 mRNA expression and suppresses specific meiotic marker synaptonemal complex protein 3 (sycp3) mRNA expression in gonads during the sexual differentiation. In conclusion, these results suggest that exposure to high temperature induces cyp26b1 mRNA expression and delays meiotic initiation of germ cells by elevating cortisol levels during gonadal sex differentiation in Japanese flounder. (C) 2012 Elsevier Inc. All rights reserved.