Department of Sports Medical, The Affiliated Ganzhou Hospital of Nanchang University, Ganzhou People's Hospital, No.17 Hongqi Avenue, Zhanggong District, Ganzhou City, 341000, Jiangxi Province, China.
J Orthop Surg Res. 2021 Jun 21;16(1):395. doi: 10.1186/s13018-021-02550-y.
Rheumatoid arthritis (RA) is a chronic inflammatory joint disease, and fibroblast-like synoviocytes (FLSs) are key effector cells in RA development. Mounting evidence indicates that circular RNAs (circRNAs) participate in the occurrence and development of RA. However, the precise mechanism of circRNA mitogen-activated protein kinase (circMAPK9) in the cell processes of FLSs has not been reported.
The expression levels of circMAPK9, microRNA-140-3p (miR-140-3p), and protein phosphatase magnesium-dependent 1A (PPM1A) were determined by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay. Cell proliferation was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell apoptosis and cycle distribution were assessed by flow cytometry. Cell migration and invasion were tested by transwell assay. All the proteins were inspected by western blot assay. Inflammatory response was evaluated by enzyme-linked immunosorbent assay (ELISA). The interaction between miR-140-3p and circMAPK9 or PPM1A was verified by dual-luciferase reporter assay.
CircMAPK9 and PPM1A were upregulated and miR-140-3p was downregulated in RA patients and FLSs from RA patients (RA-FLSs). CircMAPK9 silence suppressed cell proliferation, migration, invasion, inflammatory response, and promoted apoptosis in RA-FLSs. MiR-140-3p was a target of circMAPK9, and miR-140-3p downregulation attenuated the effects of circMAPK9 knockdown on cell progression and inflammatory response in RA-FLSs. PPM1A was targeted by miR-140-3p, and circMAPK9 could regulate PPM1A expression by sponging miR-140-3p. Furthermore, miR-140-3p could impede cell biological behaviors in RA-FLSs via targeting PPM1A.
CircMAPK9 knockdown might inhibit cell proliferation, migration, invasion, inflammatory response, and facilitate apoptosis in RA-FLSs via regulating miR-140-3p/PPM1A axis, offering a new mechanism for the comprehension of RA development and a new insight into the potential application of circMAPK9 in RA treatment.
类风湿关节炎（RA）是一种慢性炎症性关节疾病，成纤维样滑膜细胞（FLS）是 RA 发展的关键效应细胞。越来越多的证据表明，环状 RNA（circRNA）参与 RA 的发生和发展。然而，circMAPK9 在 FLS 细胞过程中的确切机制尚未报道。
采用实时定量聚合酶链反应（qRT-PCR）或 Western blot 检测 circMAPK9、微小 RNA-140-3p（miR-140-3p）和蛋白磷酸酶镁依赖性 1A（PPM1A）的表达水平。采用 3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四唑溴盐（MTT）法检测细胞增殖。通过流式细胞术评估细胞凋亡和细胞周期分布。通过 Transwell 试验检测细胞迁移和侵袭。Western blot 检测所有蛋白。酶联免疫吸附试验（ELISA）评估炎症反应。通过双荧光素酶报告基因实验验证 miR-140-3p 与 circMAPK9 或 PPM1A 的相互作用。
RA 患者和 RA 患者的成纤维样滑膜细胞（RA-FLSs）中 circMAPK9 和 PPM1A 上调，miR-140-3p 下调。circMAPK9 沉默抑制 RA-FLSs 的细胞增殖、迁移、侵袭、炎症反应，并促进细胞凋亡。miR-140-3p 是 circMAPK9 的靶标，下调 miR-140-3p 可减弱 circMAPK9 敲低对 RA-FLSs 细胞进展和炎症反应的影响。PPM1A 是 miR-140-3p 的靶点，circMAPK9 可通过海绵吸附 miR-140-3p 来调节 PPM1A 的表达。此外，miR-140-3p 可通过靶向 PPM1A 来阻碍 RA-FLSs 的细胞生物学行为。
circMAPK9 敲低可能通过调节 miR-140-3p/PPM1A 轴抑制 RA-FLSs 的细胞增殖、迁移、侵袭、炎症反应，并促进细胞凋亡，为理解 RA 发病机制提供了新的机制，并为 circMAPK9 在 RA 治疗中的潜在应用提供了新的见解。
