Department of Rehabilitation Medicine, Yantaishan Hospital, Yantai, China.
Sports Medicine, Yantaishan Hospital, Yantai, China.
J Orthop Surg Res. 2023 Jul 1;18(1):477. doi: 10.1186/s13018-023-03949-5.
It has been widely shared that the dysregulation of circular RNA (circRNA) may contribute to the progression of osteoarthritis (OA). OA is characterized by persistent chondrocyte injury. We aimed to clarify the role of circTBX5 in IL-1β-induced chondrocyte injury.
The expression of circTBX5, miR-558 and MyD88 mRNA was measured using quantitative real-time PCR (qPCR). Cell viability, proliferation and apoptosis were assessed by CCK-8, EdU or flow cytometry assay. The protein levels of extracellular matrix (ECM)-associated markers, MyD88, IkBα, p65 and phosphorylated IkBα were measured by western blot. The release of inflammatory factors was assessed by ELISA. The targets of circTBX5 were screened by RIP and pull-down assay. The putative binding between miR-558 and circTBX5 or MyD88 was validated by dual-luciferase reporter assay.
CircTBX5 and MyD88 were enhanced, while miR-558 was downregulated in OA cartilage tissues and IL-1β-treated C28/I2 cells. IL-1β induced C28/I2 cell injury by impairing cell viability and proliferation and promoting cell apoptosis, ECM degradation and inflammatory response, while circTBX5 knockdown alleviated IL-1β induced injury. CircTBX5 bound to miR-558 to regulate IL-1β induced cell injury. In addition, MyD88 was a target of miR-558, and circTBX5 targeted miR-558 to positively regulate MyD88 expression. MiR-558 enrichment attenuated IL-1β induced injury by sequestering MyD88 expression. Moreover, circTBX5 knockdown weakened the activity of NF-κB signaling, while miR-558 inhibition or MyD88 overexpression recovered the activity of NF-κB signaling.
CircTBX5 knockdown modulated the miR-558/MyD88 axis to alleviate IL-1β induced chondrocyte apoptosis, ECM degradation and inflammation via inactivating the NF-кB signaling pathway.
CircRNA（circRNA）的失调可能导致骨关节炎（OA）的进展，这一观点已被广泛认同。OA 的特征是持续性软骨细胞损伤。本研究旨在阐明 circTBX5 在 IL-1β诱导的软骨细胞损伤中的作用。
采用实时定量 PCR（qPCR）检测 circTBX5、miR-558 和 MyD88 mRNA 的表达。通过 CCK-8、EdU 或流式细胞术评估细胞活力、增殖和凋亡。通过 Western blot 检测细胞外基质（ECM）相关标志物、MyD88、IkBα、p65 和磷酸化 IkBα的蛋白水平。通过 ELISA 检测炎症因子的释放。通过 RIP 和下拉实验筛选 circTBX5 的靶点。通过双荧光素酶报告实验验证 miR-558 与 circTBX5 或 MyD88 的假定结合。
OA 软骨组织和 IL-1β处理的 C28/I2 细胞中，circTBX5 和 MyD88 上调，而 miR-558 下调。IL-1β 通过损害细胞活力和增殖，促进细胞凋亡、ECM 降解和炎症反应，诱导 C28/I2 细胞损伤，而 circTBX5 敲低则缓解了 IL-1β 诱导的损伤。CircTBX5 与 miR-558 结合，调节 IL-1β 诱导的细胞损伤。此外，MyD88 是 miR-558 的靶标，circTBX5 靶向 miR-558 以正向调节 MyD88 表达。miR-558 富集通过封闭 MyD88 表达减轻了 IL-1β 诱导的损伤。此外，circTBX5 敲低减弱了 NF-κB 信号通路的活性，而 miR-558 抑制或 MyD88 过表达恢复了 NF-κB 信号通路的活性。
circTBX5 敲低通过调节 miR-558/MyD88 轴，抑制 NF-кB 信号通路的活性，减轻 IL-1β 诱导的软骨细胞凋亡、ECM 降解和炎症，从而缓解软骨细胞损伤。
