Department of Osteonecrosis and Joint Reconstruction, Honghui Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, China.
Shaanxi University of Chinese Medicine, Xi'an, China.
J Cell Mol Med. 2021 May;25(10):4608-4622. doi: 10.1111/jcmm.16294. Epub 2021 Mar 18.
Steroid-induced osteonecrosis of the femoral head (SIONFH) has been a common disease following corticosteroid therapy. Presently, we aim to explore the functions of circular RNA (circ) PVT1 in SIONFH rats and the underlying mechanism. Glucocorticoid (GC) was used to treat SD rats and bone marrow-derived mesenchymal stem cells (BMSCs) to construct SIONFH model in vitro and in vivo, respectively. The pathological injury of the femoral head in the SIONFH rats was detected via haematoxylin-eosin (HE) staining and immunohistochemistry (IHC). The osteogenic differentiation, proliferation and apoptosis of BMSCs were detected. Western blot was used to detect Smad7, Bax, Bcl2 and Smad2/3. The potential targets of circPVT1 and miR-21-5p were validated through luciferase reporter gene assay and RNA pull-down assay, respectively. We found that CircPVT1 was decreased in the femoral head of SIONFH rats and GC-treated BMSCs, while miR-21-5p was markedly up-regulated. Overexpressed circPVT1 attenuated the apoptosis and cell viability inhibition of BMSCs induced by GC, while miR-21-5p up-regulation had the opposite effects. What's more, the in vivo experiments confirmed that up-regulating circPVT1 repressed osteonecrosis in SIONFH rats through repressing apoptosis. Mechanistically, circPVT1 functioned as a ceRNA of miR-21-5p, which targeted at the 3'untranslated region of Smad7. CircPVT1 enhancing Smad7 and mitigating GC activated TGFβ/Smad2/3 pathway through inhibiting miR-21-5p. In conclusion, CircPVT1 exerts protective effects against SIONFH via modulating miR-21-5p-mediated Smad7/TGFβ pathway.
激素诱导性股骨头坏死（Steroid-induced osteonecrosis of the femoral head，SIONFH）是皮质类固醇治疗后的一种常见疾病。目前，我们旨在探讨环状 RNA（circ）PVT1 在 SIONFH 大鼠中的作用及其潜在机制。使用糖皮质激素（Glucocorticoid，GC）分别治疗 SD 大鼠和骨髓间充质干细胞（bone marrow-derived mesenchymal stem cells，BMSCs），以构建体内和体外 SIONFH 模型。通过苏木精-伊红（haematoxylin-eosin，HE）染色和免疫组织化学（immunohistochemistry，IHC）检测 SIONFH 大鼠股骨头的病理损伤。检测 BMSCs 的成骨分化、增殖和凋亡。Western blot 检测 Smad7、Bax、Bcl2 和 Smad2/3。通过荧光素酶报告基因检测和 RNA 下拉实验分别验证 circPVT1 和 miR-21-5p 的潜在靶标。结果发现，SIONFH 大鼠股骨头和 GC 处理的 BMSCs 中 CircPVT1 减少，而 miR-21-5p 明显上调。过表达 circPVT1 可减轻 GC 诱导的 BMSCs 凋亡和细胞活力抑制，而 miR-21-5p 上调则有相反的效果。此外，体内实验证实，上调 circPVT1 通过抑制凋亡来抑制 SIONFH 大鼠的骨坏死。机制上，circPVT1 作为 miR-21-5p 的 ceRNA，靶向 Smad7 的 3'UTR。CircPVT1 通过抑制 miR-21-5p 增强 Smad7，减轻 GC 激活的 TGFβ/Smad2/3 通路。综上所述，CircPVT1 通过调节 miR-21-5p 介导的 Smad7/TGFβ 通路对 SIONFH 发挥保护作用。
