State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
Brain Research Institute, Jeffrey Cheah School of Medicine and Health Science, Monash University Malaysia, Bandar Sunway 47500, Malaysia.
Mol Cell Endocrinol. 2018 Feb 5;461:1-11. doi: 10.1016/j.mce.2017.08.003. Epub 2017 Aug 8.
The LHb expression is up-regulated during puberty in female zebrafish. However, the molecular mechanism underlying how LHb expression is regulated during puberty remains largely unknown. In this study, we found that the mRNA expression levels of lhb, fshb and cyp19a1b were up-regulated along with the puberty onset in zebrafish. Among the three nuclear estrogen receptors (nERs), the esr2b is the only type whose expression is significantly up-regulated during puberty onset in the pituitary. However, in situ hybridization results revealed that lhb mRNA was colocalized with esr1 and esr2a but not esr2b. Exposure to estradiol (E) significantly stimulates LHb expression in both wild-type and kiss1;kiss2;gnrh3 triple knockout pubertal zebrafish. Moreover, exposure of cultured pituitary cells to E increased the LHb expression, indicating that the estrogenic effect on LHb expression could be acted at the pituitary level. Finally, we cloned and analyzed the promoter of lhb by luciferase assay. Our results indicated that the E responsive regions of lhb promoter for ERα and ERβ2 are identical, suggesting that ERα and ERβ2 could bind to the same half ERE region of the promoter of lhb, exhibiting a classical ERE-dependent pathway. In summary, we demonstrate that E could directly act on the pituitary level to stimulate LHb transcription during puberty in zebrafish.
在青春期，斑马鱼的 LHb 表达上调。然而，LHb 表达在青春期如何被调控的分子机制在很大程度上仍然未知。在这项研究中，我们发现 lhb、fshb 和 cyp19a1b 的 mRNA 表达水平随着斑马鱼青春期的开始而上调。在三种核雌激素受体（nERs）中，esr2b 是唯一一种在垂体中青春期开始时表达显著上调的类型。然而，原位杂交结果显示，lhb mRNA 与 esr1 和 esr2a 共定位，但与 esr2b 不共定位。暴露于雌二醇（E）显著刺激野生型和 kiss1;kiss2;gnrh3 三重敲除青春期斑马鱼的 LHb 表达。此外，培养的垂体细胞暴露于 E 增加了 LHb 的表达，表明雌激素对 LHb 表达的影响可以在垂体水平上发挥作用。最后，我们通过荧光素酶检测克隆和分析了 lhb 的启动子。我们的结果表明，lhb 启动子的 ERα 和 ERβ2 响应区是相同的，表明 ERα 和 ERβ2 可以结合到 lhb 启动子的相同 ERE 半区域，表现出经典的 ERE 依赖途径。总之，我们证明了 E 可以直接在垂体水平上作用于青春期的斑马鱼，刺激 LHb 的转录。
