Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Bio-X Institutes, Shanghai Jiao Tong University, Shanghai 200240, China.
Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Bio-X Institutes, Shanghai Jiao Tong University, Shanghai 200240, China; Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education, Ningxia Medical University, Yinchuan 750004, China; State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200032, China.
Metabolism. 2018 Aug;85:192-204. doi: 10.1016/j.metabol.2018.04.002. Epub 2018 Apr 7.
Circular RNAs (circRNAs) are a class of noncoding RNAs that can regulate gene expression at the post-transcriptional level. The contribution of circRNAs in the regulation of granulosa cells (GCs) functions is not yet clear. The aim of this study was to analyze circRNA expression in adult and neonate ovaries, uncover the biological roles of circ_0002861 (circEGFR) and identify the mechanism by which it modulates follicular development.
The circRNA expression profiles of adult and neonatal mouse ovaries were explored by high-throughput sequencing. The function of circEGFR was measured by RNA fluorescence in situ hybridization, overexpression, knockdown, RNA immunoprecipitation and luciferase reporter assays in GCs.
Numerous differentially expressed circRNAs were identified in adult and neonatal ovaries. Through circRNAs expression patterns and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, estrogen signaling was found to be upregulated in adult ovaries compared with neonate ovaries. Further analysis revealed that the expression of circEGFR (circ_0002861, ID: mmu_circ_0002861 in circBase) was increased in adult ovaries compared with neonate ovaries. circEGFR is formed by splicing from exons 14 and 15 of the epidermal growth factor receptor (EGFR) gene to produce a covalently linked 249-nucleotide circRNA. Overexpression of circEGFR increased estradiol (E) production and GCs growth, whereas circEGFR knockdown enhanced progesterone production and inhibited (E) secretion by GCs. Bioinformatic screening identified several binding sites for miR-125a-3p in the circEGFR sequence. RNA immunoprecipitation and luciferase reporter assays demonstrated that circEGFR may act as a sponge for miR-125a-3p, thus modulating Fyn expression.
These findings illustrate that circEGFR may play a vital role in ovarian GCs by modulating Fyn via competitive binding with miR-125a-3p. Our results suggest potential applications of circEGFR in reproductive and steroid-related disorder therapy.
环状 RNA（circRNA）是一类非编码 RNA，可在后转录水平调节基因表达。环状 RNA 在调控颗粒细胞（GC）功能中的作用尚不清楚。本研究旨在分析成年和新生卵巢中的环状 RNA 表达谱，揭示 circ_0002861（circEGFR）的生物学作用，并确定其调节卵泡发育的机制。
通过高通量测序探讨成年和新生小鼠卵巢中的环状 RNA 表达谱。通过 RNA 荧光原位杂交、在 GC 中过表达、敲低、RNA 免疫沉淀和荧光素酶报告基因测定来测量 circEGFR 的功能。
在成年和新生卵巢中鉴定出许多差异表达的环状 RNA。通过环状 RNA 表达模式和京都基因与基因组百科全书（KEGG）通路分析，发现与新生卵巢相比，成年卵巢中的雌激素信号转导上调。进一步分析表明，circEGFR（circ_0002861，在 circBase 中的 ID:mmu_circ_0002861）在成年卵巢中的表达高于新生卵巢。circEGFR 是由表皮生长因子受体（EGFR）基因的外显子 14 和 15 拼接而成，产生一个共价连接的 249 个核苷酸的环状 RNA。circEGFR 的过表达增加了雌二醇（E）的产生和 GC 的生长，而 circEGFR 的敲低增强了孕酮的产生并抑制了 GC 分泌（E）。生物信息学筛选鉴定出 circEGFR 序列中几个与 miR-125a-3p 结合的位点。RNA 免疫沉淀和荧光素酶报告基因测定表明，circEGFR 可能作为 miR-125a-3p 的海绵，从而调节 Fyn 的表达。
这些发现表明，circEGFR 通过与 miR-125a-3p 竞争结合来调节 Fyn，从而在卵巢 GC 中发挥重要作用。我们的研究结果表明 circEGFR 在生殖和类固醇相关疾病的治疗中具有潜在的应用价值。
