Fan Zhaofei, Zou Yuxia, Jiao Shuang, Tan Xungang, Wu Zhihao, Liang Dongdong, Zhang Peijun, You Feng
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, PR China; University of Chinese Academy of Sciences, Beijing 10049, PR China.
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, PR China.
Comp Biochem Physiol A Mol Integr Physiol. 2017 Jun;208:70-79. doi: 10.1016/j.cbpa.2017.02.017. Epub 2017 Feb 17.
The sex ratio of olive flounder Paralichthys olivaceus is sensitive to temperature or exogenous hormone exposures in the period of gonadal differentiation. Among sex-related genes, cyp19a, encoding cytochrome P450 aromatase, exhibits significant sex-dimorphic expression pattern and plays an important role in fish gonadal differentiation and development. The present study investigated the expression levels and promoter methylation dynamics of cyp19a and its regulators (nr5a2 and nr0b1), and sex-steroid hormone levels during flounder gonadal differentiation under the treatments of high temperature and estradiol-17β (E2). The results showed that levels of flounder cyp19a expression and estradiol-17β were repressed by high temperature treatment during this period. The up-regulation of nr5a2 by E2 treatment may be related to the all-female formation, and up-regulation of nr0b1 by high temperature treatment may be associated with masculinization. Co-transfection assay indicated that nr5a2 and nr0b1 were antagonist regulators of cyp19a. Furthermore, cyp19a promoter exhibited significant demethylation phenomenon at early stage of ovarian differentiation. While, high temperature could repress the demethylation process, resulting in hypermethylation maintenance in cyp19a promoter. The hypermethylation promoter was able to suppress cyp19a expression by blocking the nr5a2-mediated transactivation activity in vitro. The DNA methylation of epigenetic modification in cyp19a promoter might be the vital way linking environmental factors and gonadal differentiation in flounder.
牙鲆（Paralichthys olivaceus）的性别比例在性腺分化期对温度或外源激素暴露敏感。在与性别相关的基因中，编码细胞色素P450芳香化酶的cyp19a呈现出显著的性别二态性表达模式，并在鱼类性腺分化和发育中发挥重要作用。本研究调查了高温和17β-雌二醇（E2）处理下牙鲆性腺分化过程中cyp19a及其调节因子（nr5a2和nr0b1）的表达水平、启动子甲基化动态以及性类固醇激素水平。结果表明，在此期间高温处理抑制了牙鲆cyp19a表达水平和17β-雌二醇水平。E2处理使nr5a2上调可能与全雌形成有关，高温处理使nr0b1上调可能与雄性化有关。共转染试验表明，nr5a2和nr0b1是cyp19a的拮抗调节因子。此外，cyp19a启动子在卵巢分化早期表现出显著的去甲基化现象。然而，高温可抑制去甲基化过程，导致cyp19a启动子维持高甲基化状态。在体外，高甲基化启动子能够通过阻断nr5a2介导的反式激活活性来抑制cyp19a表达。cyp19a启动子表观遗传修饰中的DNA甲基化可能是连接环境因素与牙鲆性腺分化的关键途径。
