Pregnancy success requires a proper fetal maternal interaction at the establishment of implantation. Leptin has been described as a multitasking cytokine in pregnancy, particularly in the placenta, where it acts as an autocrine hormone. The expression of leptin in normal trophoblastic cells is regulated by different endogenous signals. We have previously reported that 17β-estradiol up-regulates placental leptin expression through genomic and non-genomic mechanisms. To improve the knowledge of estrogen receptor mechanisms in regulating leptin gene expression, we examined transcription nuclear factor kappa B (NFκB) effect on estradiol leptin induction in human BeWo cell line and human term placental explants. We demonstrated that estradiol induction effect on leptin expression is blocked by the inhibition of NFκB signaling. We also found that the overexpression of p65 subunit, the active form of NFκB, induces leptin expression. Moreover, the downregulation of estrogen receptor alpha (ERα through a specific siRNA, abolished NFκB effect on leptin expression. We also demonstrated that ERα enhanced NFκB signaling pathway activation in trophoblastic cells. Estradiol treatment significantly increased p65 expression and phosphorylation of the inhibitory protein κB alpha (IκBα). A reporter plasmid containing NFκB elements was also induced in response to estradiol stimulation. Localization experiments revealed that estradiol treatment induced nuclear localization of overexpressed p65. Moreover, the overexpression of ERα produced a complete displacement of p65 protein to the nucleus. Finally, immunoprecipitation experiments showed the presence of a complex containing ERαand NFκB. All these evidences suggest a cooperative behavior between ERαand NFκB transcription factors to induce leptin transcription.

中文翻译：

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雌二醇和 NFκB 信号通路之间的串扰对胎盘瘦素表达的影响

妊娠成功需要在植入时进行适当的胎儿母体相互作用。瘦素被描述为怀孕期间的多任务细胞因子，尤其是在胎盘中，它充当自分泌激素。正常滋养细胞中瘦素的表达受不同内源性信号的调节。我们之前曾报道过，17β-雌二醇通过基因组和非基因组机制上调胎盘瘦素表达。为了提高对调节瘦素基因表达的雌激素受体机制的了解，我们检查了转录核因子 kappa B (NFκB) 对人 BeWo 细胞系和人足月胎盘外植体中雌二醇瘦素诱导的影响。我们证明雌二醇对瘦素表达的诱导作用被 NFκB 信号传导的抑制所阻断。我们还发现 p65 亚基（NFκB 的活性形式）的过度表达会诱导瘦素表达。此外，雌激素受体α（ERα通过特定siRNA的下调，消除了NFκB对瘦素表达的影响。我们还证明ERα增强了滋养层细胞中NFκB信号通路的激活。雌二醇处理显着增加了p65表达和抑制蛋白κBα的磷酸化(IκBα) 含有 NFκB 元件的报告质粒也被诱导以响应雌二醇刺激。定位实验表明，雌二醇处理诱导过表达 p65 的核定位。此外，ERα 的过表达导致 p65 蛋白完全置换到细胞核。最后, 免疫沉淀实验表明存在含有 ERα 和 NFκB 的复合物。所有这些证据表明 ERα 和 NFκB 转录因子之间存在协同行为以诱导瘦素转录。