LncRNA ZFAS1 protects chondrocytes from IL-1β-induced apoptosis and extracellular matrix degradation via regulating miR-7-5p/FLRT2 axis.

Increasing evidence suggested that long non-coding RNAs (lncRNAs) played vital roles in osteoarthritis (OA) progression. In this study, we aimed to reveal the protective roles of lncRNA ZFAS1 in osteoarthritis (OA) and further investigated its underlying mechanism. The chondrocytes were stimulated by IL-1β to establish an in vitro OA model. Then, the expression of ZFAS1, miR-7-5p, and FLRT2 in chondrocytes was determined by qRT-PCR. Gain- and loss-of-function assays of ZFAS1, miR-7-5p and FLRT2 were conducted. CCK-8 assay and flow cytometry analysis were performed to detect cell viability and apoptosis rate. The expression levels of cartilage-related proteins, including MMP13, ADAMTS5, Collagen II, and Aggrecan, were measured by western blot analysis. The interaction between ZFAS1 and miR-7-5p, as well as miR-7-5p and FLRT2, was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. The expression of ZFAS1 and FLRT2 was down-regulated, while the expression of miR-7-5p was up-regulated in chondrocytes exposed to IL-1β. ZFAS1 overexpression promoted cell viability and suppressed apoptosis in IL-1β-treated chondrocytes. Besides, ZFAS1 overexpression suppressed the expression of MMP13 and ADAMTS5, but promoted the expression of Collagen II and Aggrecan to suppress ECM degradation. The mechanistic study showed that ZFAS1 sponged miR-7-5p to regulate FLRT2 expression. Furthermore, the overexpression of miR-7-5p could neutralize the effect of ZFAS1 in IL-1β-treated chondrocytes, and suppression of FLRT2 counteracted the miR-7-5p down-regulation role in IL-1β-treated chondrocytes. ZFAS1 could promote cell viability of IL-1β-treated chondrocytes via regulating miR-7-5p/FLRT2 axis. Trial registration Not applicable.

Han J ，Luo Z ，Wang Y ，Liang Y ... -  《Journal of Orthopaedic Surgery and Research》

SNHG5 protects chondrocytes in interleukin-1β-stimulated osteoarthritis via regulating miR-181a-5p/TGFBR3 axis.

Yue Y ，Zhibo S ，Feng L ，Yuanzhang B ，Fei W ... -  《-》

CircRNA circ_SEC24A upregulates DNMT3A expression by sponging miR-26b-5p to aggravate osteoarthritis progression.

Osteoarthritis (OA) is a chronic degenerative disease characterized by degeneration and injury of articular cartilage. Circular RNA_SEC24A (circ_SEC24A; circBase ID: hsa_circ_0005105) is upregulated and promotes multiple tumor processes. However, its role in OA progression remained mostly unknown. Quantitative real-time PCR (qRT-PCR) was used to detect the RNA expression of circ_SEC24A, miR-26b-5p and DNA methyltransferase 3 alpha (DNMT3A). Cell proliferation was verified by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) and 5-ethynyl-2'-deoxyuridine (EdU) assays. Flow cytometry was used to detect apoptosis. Western blot was used to detect protein expression of DNMT3A, proliferating cell nuclear antigen (PCNA), extracellular matrix (ECM) proteins (Collagen II and Aggrecan), and ECM degrading enzymes (matrix metalloproteinase-13 [MMP13] and metallopeptidase with thrombospondin type 1 motif 5 [ADAMTS5]). The target relationship between miR-26b-5p and circ_SEC24A or DNMT3A was predicted by Statbase3.0 or TargetScan and confirmed by dual-luciferase reporter assay, RNA pull-down assay and RNA immunoprecipitation. Circ_SEC24A was upregulated in osteoarthritic cartilage tissues and IL-1β-induced chondrocytes, accompanying with miR-26b-5p downregulation and DNMT3A upregulation. Circ_SEC24A expression was resistant to RNase R digestion and mainly expressed in the cytoplasm. Interfering circ_SEC24A abolished IL-1β-induced effects on proliferation inhibition, apoptosis, and ECM degradation in chondrocytes, but overexpressing circ_SEC24A had the opposite effects. Inhibiting miR-26b-5p counteracted but upregulating miR-26a-5p mimicked the functions of circ_SEC24A silencing. Reinforcing DNMT3A reversed miR-26b-5p overexpression's role in IL-1β-induced chondrocytes. Mechanically, circ_SEC24A and DNMT3A were competitive endogenous RNAs (ceRNAs) for miR-26b-5p. Circ_SEC24A was a promoting factor for IL-1β-induced OA progression via circ_SEC24A/miR-26b-5p/DNMT3A ceRNA axis.

Zhang Z ，Yang B ，Zhou S ，Wu J ... -  《-》

LncRNA SNHG5 promotes chondrocyte proliferation and inhibits apoptosis in osteoarthritis by regulating miR-10a-5p/H3F3B axis.

Jiang H ，Pang H ，Wu P ，Cao Z ，Li Z ，Yang X ... -  《-》

Circ_0022383 alleviates IL-1β-induced apoptosis, inflammation and extracellular matrix degeneration in osteoarthritis cell model by miR-3619-5p/SIRT1 axis.

Circular RNAs (circRNAs) have been identified to play roles in cartilage homeostasis and chondrocyte development, and be associated with osteoarthritis (OA) pathophysiology. Here, we aimed to investigate the role and mechanism of circ_0022383 on OA progression. Chondrocytes in functional groups were treated with interleukin (IL)-1β. The levels of genes and proteins were assayed by qRT-PCR and western blotting. Cell proliferation and apoptosis were evaluated by cell counting kit-8 assay, 5-Ethynyl-2'-deoxyuridine (Edu) assay, and flow cytometry, respectively. The inflammation and extracellular matrix (ECM) degeneration were determined by assessing the activity of IL-6, tumor necrosis factor (TNF-α), Aggrecan (ACAN), collagen type II α 1 chain (COL2A1) and ADAMTS5 proteins. The binding between miR-3619-5p and circ_0022383 or silent information regulator 1 (SIRT1) was confirmed by dual-luciferase reporter, RIP and RNA pull-down assays. Circ_0022383 expression was lower in the cartilages of OA patients and IL-1β-induced primary chondrocytes. Functionally, ectopic overexpression of circ_0022383 alleviated IL-1β-induced proliferation arrest, apoptosis, the release of IL-6 and TNF-α, as well as the decrease of ACAN and COL2A1 and the increase of ADAMTS5 level in chondrocytes. Mechanistically, circ_0022383 acted as a sponge for miR-3619-5p, which was verified to target SIRT1. Rescue experiments showed that miR-3619-5p up-regulation reversed the protective effects of circ_0022383 on IL-1β-stimulated chondrocytes. Additionally, miR-3619-5p inhibition abolished IL-1β-induced apoptosis, inflammation and ECM degeneration in chondrocytes, which were counteracted by SIRT1 silencing. Circ_0022383 protected chondrocytes from IL-1β-induced apoptosis, inflammation and ECM degeneration by miR-3619-5p/SIRT1 axis, inspiring future therapy development for OA prevention.

Qian L ，Yu B ，Chen T ，Chen K ，Ma Z ，Wang Y ，Sun B ... -  《-》