淫羊藿苷调控激素性股骨头坏死BMSC分化失衡的表观遗传机制研究

The imbalance of BMSCs' osteogenesis and adipogenesis is the main pathogenesis and target of steroid-associated osteonecrosis of femoral head (ONFH). It has been confirmed that UTX and EZH2 act as an epigenetic switch to regulate BMSCs lineage specification. Our previous research showed that icariin could make the dynamic balance between osteogenesis and adipogenesis by the inhibition of DNA hypermethylation. However, the precious epigenetic mechanism is unknown. In the preliminary study, we observed that icariin could promote UTX and down-regulate EZH2. We infer that UTX and EZH2 may be the key targets of icariin. We plan to over-express UTX or silence EZH2, perform western blot, ChIP and BSP to investigate whether icariin activates osteogenic genes and keeps normal differentiation of BMSCs by the modulation of UTX and EZH2. This study will provide some more experimental evidence on epigenetic modulation of icariin.

骨髓间充质干细胞(BMSCs)成骨-成脂分化失衡是激素性骨坏死重要的发病机制和治疗的中心环节。已证实UTX和EZH2作为一对表观遗传调控开关对BMSCs分化起关键作用。申请人前期工作显示淫羊藿苷通过抑制激素性骨坏死BMSCs DNA过甲基化修饰来恢复成骨与成脂的动态平衡(Sun ZB, et al. Osteoporos Int. 2015, 26(1):187-197.)，但其确切的表观调控机制尚不清楚。预实验发现骨坏死组BMSCs在淫羊藿苷刺激后UTX显著升高、EZH2显著降低。我们推测UTX和EZH2可能是淫羊藿苷表观调控的关键因子，拟采用慢病毒介导的RNA干扰和过表达、免疫印迹、ChIP、亚硫酸氢盐测序等技术，探讨淫羊藿苷是否通过调控UTX和EZH2，抑制H3K27甲基化，激活成骨相关基因以扭转BMSCs分化失衡现象。如获成功，该研究将为拓展淫羊藿苷的表观遗传靶向治疗提供科学依据。

骨髓间充质干细胞(BMSCs)成骨-成脂分化失衡是激素性骨坏死重要的发病机制和治疗的中心环节。已证实UTX和EZH2作为一对表观遗传调控开关对BMSCs分化起关键作用。前期工作显示淫羊藿苷通过抑制激素性骨坏死BMSCs DNA过甲基化修饰来恢复成骨与成脂的动态平衡。本课题应用慢病毒介导的RNA干扰和过表达、免疫印迹、亚硫酸氢盐测序等技术，通过体内及体外实验，证实了激素性股骨头坏死疾病中BMSCs成骨-成脂分化失衡及异常的表观遗传状态与PI3K-AKT-UTX/EZH2信号通路的持续抑制存在关联。UTX和EZH2是淫羊藿苷表观调控的关键因子，淫羊藿苷通过激活PI3K/AKT信号通路上调UTX表达，抑制EZH2表达与活性，从而移除H3K27me3标记，逆转BMSCs异常的表观修饰谱式，恢复成骨与成脂的动态平衡，这对防治早期激素性股骨头坏死具有重要意义。该课题已取得良好的预期目标，为拓展淫羊藿苷的表观遗传靶向治疗奠定了理论和实验基础。