Circular RNA (circRNA) participates in regulation of gene transcription, while estrogen receptor alpha (ERα) and quercetin (QUE) positively regulate bone formation, but little is known about the correlation among circRNA, ERα and QUE. In this experiment, we created an ERα-deficient rBMSC model treated with QUE and evaluated the effects of ERα or QUE on rBMSCs, then analyzed differentially-expressed circRNAs by RNA-Seq and bioinformatics. The results showed that ERα deficiency constrained osteogenic differentiation and stimulated adipocytic differentiation of rBMSCs, while QUE abrogated those effects. We identified 136 differentially-expressed circRNAs in the Lv-shERα group and 120 differentially-expressed circRNAs in the Lv-shERα+QUE group. Thirty-two circRNAs retroregulated by ERα and QUE were involved in Rap1 and Wnt signaling, and four of them together sponged miR-326-5p, the target genes of which are osteogenic and adipogenic differentiation factors. Further study showed that over-expressed miR-326-5p could stimulate osteogenic differentiation, while attenuating adipogenic differentiation of rBMSCs. Therefore, we concluded that ERα and QUE might regulate the differentiation of rBMSCs through the circRNA–miR-326-5p–mRNA axis.

环状RNA（circRNA）参与基因转录的调节，而雌激素受体α（ERα）和槲皮素（QUE）积极调节骨形成，但关于circRNA，ERα和QUE的相关性知之甚少。在此实验中，我们创建了用QUE处理的ERα缺陷型rBMSC模型，并评估了ERα或QUE对rBMSC的作用，然后通过RNA-Seq和生物信息学分析了差异表达的circRNA。结果表明，ERα缺乏限制了rBMSCs的成骨分化并刺激了脂肪细胞的分化，而QUE则废除了这些作用。我们在Lv-shERα组中鉴定了136个差异表达的circRNA，在Lv-shERα+ QUE组中鉴定了120个差异表达的circRNA。Rap1和Wnt信号转导涉及ERα和QUE逆转录的32个circRNA，它们中的四个一起是海绵状miR-326-5p，其目标基因是成骨和成脂分化因子。进一步的研究表明，过量表达的miR-326-5p可以刺激成骨细胞分化，同时减弱rBMSCs的成脂细胞分化。因此，我们得出结论，ERα和QUE可能通过circRNA–miR-326-5p–mRNA轴调控rBMSC的分化。