Li Yuanyuan, Li Jinbo, Shen Yanping, Xiong Yiming, Li Xinghong, Qin Zhanfen
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Aquat Toxicol. 2021 Jan 21;232:105760. doi: 10.1016/j.aquatox.2021.105760.
Estrogens and estrogenic endocrine disrupting chemicals can cause gonadal feminization in some vertebrates mainly through estrogen receptor (ER), but the underlying molecular mechanisms are unclear. The present study aimed to identify ER target genes involved in estrogen-caused gonadal feminization in Xenopus laevis. Based on our recent transcriptomic data that 10 nM 17β-estradiol (E2) altered gene transcription in feminizing gonads of male X. laevis at NF stages 48, 50, and 52, we searched estrogen response element (ERE) using the Dragon ERE Finder software in the promoter region of all the E2-regulated genes. As a result, 163 genes containing ERE sequence were identified as predicted ER target genes at NF stage 50 (on the 14th day postfertilization), a crucial stage for gonadal feminization. Then, some of these predicted ER target genes were further investigated, mainly including the genes that were suggested to be involved in E2-caused gonadal feminization and genes being dramatically up or down-regulated by E2. Fifteen genes were demonstrated to be responsive to E2, in turn ER antagonist blocked the E2-regulated transcription. Finally, we identified 10 genes that can bind to ERα by a chromatin immunoprecipitation-qPCR. Taken together, we identified the 10 genes that contain predicted ERE sequences, are responsive to estrogen and ER antagonist, and have ability to bind to ER as ER target genes, including pglyrp2, apoa1, fgb, tdo2, ca6, nags, cpb2, tmprss6, nudc, zwilch. Our results could help to improve the understanding of the molecular mechanisms for gonadal feminization caused by estrogenic endocrine disrupting chemicals in X. laevis, and even in other species.
雌激素和具有雌激素活性的内分泌干扰化学物质可主要通过雌激素受体（ER）在一些脊椎动物中导致性腺雌性化，但其潜在的分子机制尚不清楚。本研究旨在鉴定非洲爪蟾中参与雌激素引起的性腺雌性化的ER靶基因。基于我们最近的转录组数据，即10 nM 17β-雌二醇（E2）在NF阶段48、50和52改变了雄性非洲爪蟾雌性化性腺中的基因转录，我们使用Dragon ERE Finder软件在所有E2调控基因的启动子区域搜索雌激素反应元件（ERE）。结果，在NF阶段50（受精后第14天），一个性腺雌性化的关键阶段，鉴定出163个含有ERE序列的基因作为预测的ER靶基因。然后，对其中一些预测的ER靶基因进行了进一步研究，主要包括那些被认为参与E2引起的性腺雌性化的基因以及被E2显著上调或下调的基因。有15个基因被证明对E2有反应，反过来，ER拮抗剂阻断了E2调控的转录。最后，我们通过染色质免疫沉淀-qPCR鉴定出10个能与ERα结合的基因。综上所述，我们鉴定出10个含有预测ERE序列、对雌激素和ER拮抗剂有反应且具有与ER结合能力的基因作为ER靶基因，包括pglyrp2、apoa1、fgb、tdo2、ca6、nags、cpb2、tmprss6、nudc、zwilch。我们的结果有助于增进对雌激素性内分泌干扰化学物质在非洲爪蟾甚至其他物种中引起性腺雌性化的分子机制的理解。
