Li Peng, Mao Weiwei, Zhang Shuai, Zhang Liang, Chen Zhirong, Lu Zhidong
Department of Orthopedics, General Hospital of Ningxia Medical University, Yinchuan, Ningxia 750004, P.R. China.
Clinical Skill Center of Yinchuan First People's Hospital, Yinchuan, Ningxia 750001, P.R. China.
Exp Ther Med. 2021 Apr;21(4):336. doi: 10.3892/etm.2021.9767. Epub 2021 Feb 8.
Osteoporosis is a common complication of long-term use of glucocorticoids (GCs) characterized by the loss of bone mass and damage of the microarchitecture as well as osteoblast dysfunction. Previous studies have demonstrated that microRNA-22 (miR-22) is the negative modulator of osteogenesis that may target caveolin-3 (CAV3), which has been reported to enhance bone formation and inhibit the progression of osteoporosis as well as apoptosis. The present study aimed to investigate whether miR-22 may be involved in dexamethasone (DEX)-induced inhibition of osteoblast differentiation and dysfunction by regulating CAV3 expression. Reverse transcription-quantitative PCR (RT-qPCR) was performed to measure the expression of miR-22 and western blotting was performed to determine protein levels. The results demonstrated that miR-22 expression was upregulated in DEX-treated osteoblastic cells compared with the control group. In addition, miR-22 mimic aggravated, whereas miR-22 inhibitor mitigated DEX-induced damage in osteoblastic cells compared with the control groups. Additionally, CAV3 was identified as the target of miR-22 in osteoblasts using RT-qPCR, western blotting and dual-luciferase reporter gene assay analysis. The results also demonstrated that silencing of CAV3 blocked the beneficial effects of miR-22 inhibitor against DEX-induced cell damage and apoptosis in osteoblasts, as evidenced by the increased expression levels of cleaved caspase-3, Bax and alkaline phosphatase activity as well as decreased cell viability and Bcl-2 levels. Collectively, these results indicate a novel molecular mechanism by which miR-22 contributes to DEX-induced osteoblast dysfunction and apoptosis via the miR-22/CAV3 pathway.
骨质疏松症是长期使用糖皮质激素（GCs）的常见并发症，其特征为骨量丢失、微结构破坏以及成骨细胞功能障碍。既往研究表明，微小RNA-22（miR-22）是成骨作用的负性调节因子，其可能靶向小窝蛋白-3（CAV3），据报道CAV3可促进骨形成、抑制骨质疏松症进展及细胞凋亡。本研究旨在探讨miR-22是否可能通过调节CAV3表达参与地塞米松（DEX）诱导的成骨细胞分化抑制和功能障碍。采用逆转录定量聚合酶链反应（RT-qPCR）检测miR-22表达，采用蛋白质印迹法测定蛋白质水平。结果显示，与对照组相比，DEX处理的成骨细胞中miR-22表达上调。此外，与对照组相比，miR-22模拟物加重了DEX诱导的成骨细胞损伤，而miR-22抑制剂减轻了这种损伤。另外，通过RT-qPCR、蛋白质印迹法和双荧光素酶报告基因分析，确定CAV3为成骨细胞中miR-22的靶标。结果还表明，沉默CAV3可阻断miR-22抑制剂对DEX诱导的成骨细胞损伤和细胞凋亡的有益作用，这表现为裂解的半胱天冬酶-3、Bax表达水平增加以及碱性磷酸酶活性增加，同时细胞活力和Bcl-2水平降低。总体而言，这些结果表明了一种新的分子机制，即miR-22通过miR-22/CAV3途径导致DEX诱导的成骨细胞功能障碍和细胞凋亡。
