Department of Cell and Developmental Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China.
Mol Cell Endocrinol. 2013 May 6;370(1-2):119-29. doi: 10.1016/j.mce.2013.02.014. Epub 2013 Mar 5.
MicroRNAs (miRNAs) have been indicated to play key roles in ovarian follicular development. However, little is known about how the miRNA gene expression itself is regulated in the mammalian ovary. We previously reported that miR-224 is involved in TGF-β1-mediated follicular granulosa cell (GC) growth and estradiol (E2) production by targeting Smad4. Here, the transcriptional regulation of miR-224 expression in GCs was further investigated. Our results showed that both the tumor suppressor gene p53 and NF-κB p65 subunit suppressed the TGF-β1-induced increase in pri-miR-224 expression in GCs. ChIP assays demonstrated that TGF-β1 enhanced the binding of p53 and p65 to the proximal promoter region of GABAA receptor ε subunit (miR-224 host gene). p53 and p65 transcriptionally cooperated to inactivate the GABAA receptor ε subunit promoter. In addition, p53/p65 could up-regulate Smad4 expression by inhibiting its target miR-224 in GCs which contributed, at least partially, to the effects of miR-224 and Smad4 on GC proliferation and E2 release. Our results provide new data about the interplay between transcription factors involved in GC proliferation and function by cooperatively regulating miRNA expression.
微小 RNA（miRNA）已被证明在卵巢卵泡发育中发挥关键作用。然而，对于 miRNA 基因表达本身如何在哺乳动物卵巢中受到调控，人们知之甚少。我们之前的研究表明，miR-224 通过靶向 Smad4 参与 TGF-β1 介导的卵泡颗粒细胞（GC）生长和雌二醇（E2）的产生。在这里，我们进一步研究了 GC 中 miR-224 表达的转录调控。我们的研究结果表明，抑癌基因 p53 和 NF-κB p65 亚基均抑制 TGF-β1 诱导的 GC 中 pri-miR-224 表达的增加。ChIP 分析表明，TGF-β1 增强了 p53 和 p65 与 GABAA 受体 ε 亚基（miR-224 宿主基因）近端启动子区域的结合。p53 和 p65 转录协同作用使 GABAA 受体 ε 亚基启动子失活。此外，p53/p65 可以通过抑制其靶基因 miR-224 来上调 Smad4 的表达，这至少部分有助于 miR-224 和 Smad4 对 GC 增殖和 E2 释放的影响。我们的研究结果提供了新的数据，表明参与 GC 增殖和功能的转录因子通过协同调控 miRNA 表达相互作用。
