CircRNA circ-IQGAP1 Knockdown Alleviates Interleukin-1β-Induced Osteoarthritis Progression via Targeting miR-671-5p/TCF4.

To explore the function of circular RNA IQ motif-containing GTPase-activating protein 1 (circ-IQGAP1) in interleukin (IL)-1β-induced osteoarthritis (OA) model and to explore whether circ-IQGAP1 can modulate microRNA-671-5p (miR-671-5p) and transcription factor 4 (TCF4) to regulate chondrocyte apoptosis, inflammatory injury, and extracellular matrix degradation. The cartilage tissues were collected from 32 OA patients or normal subjects. Human chondrocyte CHON-001 cells were challenged via different doses of IL-1β for 24 hours. CHON-001 cells were transfected with circ-IQGAP1 overexpression vector, TCF4 overexpression vector, small interfering RNA (siRNA) for circ-IQGAP1, miR-671-5p mimic, miR-671-5p inhibitor or corresponding negative controls. Circ-IQGAP1, miR-671-5p and TCF4 abundances in cartilage tissues or CHON-001 cells were examined via quantitative reverse transcription polymerase chain reaction (qRT-PCR) or western blot. Cell viability was investigated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT). Cell apoptosis was measured by flow cytometry. The inflammatory injury was analyzed by the secretion levels of inflammatory cytokines (IL-6, IL-8 and tumor necrosis factor-α [TNF-α]) by enzyme-linked immunosorbent assay (ELISA). The extracellular matrix degradation was evaluated by expression of aggrecan and matrix metalloproteinase 13 (MMP13) via western blot. The target relationship of miR-671-5p and circ-IQGAP1 or TCF4 was analyzed via dual-luciferase reporter and RNA immunoprecipitation (RIP) analyses. Circ-IQGAP1 abundance was enhanced in the cartilage tissues from OA patients compared with normal subjects (n = 32), and its expression was increased in CHON-001 cells after treatment of IL-1β in a dose-dependent pattern. MiR-671-5p expression was decreased in the cartilage tissues from OA patients (n = 32) and IL-1β-challenged CHON-001 cells. MiR-671-5p expression was negatively associated with circ-IQGAP1 level in OA patients. Circ-IQGAP1 silence mitigated IL-1β-caused chondrocyte viability reduction, apoptosis promotion, secretion of inflammatory cytokine (IL-6, IL-8 and TNF-α), and extracellular matrix degradation (reduction of aggrecan and increase of MMP13). MiR-671-5p was targeted and inhibited via circ-IQGAP1. MiR-671-5p knockdown attenuated the influence of circ-IQGAP1 interference on IL-1β-caused chondrocyte apoptosis, inflammatory injury, and extracellular matrix degradation. TCF4 was targeted via miR-671-5p, and TCF4 expression was increased in the cartilage tissues from OA patients (n = 32) and IL-1β-challenged CHON-001 cells. TCF4 abundance in OA patients was negatively correlated with miR-671-5p expression. MiR-671-5p overexpression alleviated IL-1β-mediated chondrocyte apoptosis, inflammatory injury, and extracellular matrix degradation via decreasing TCF4 expression. Circ-IQGAP1 silence reduced TCF4 expression via regulating miR-671-5p in IL-1β-challenged CHON-001 cells. Circ-IQGAP1 knockdown attenuated IL-1β-caused chondrocyte apoptosis, inflammatory injury, and extracellular matrix degradation. Circ-IQGAP1 could regulate miR-671-5p/TCF4 axis to modulate IL-1β-caused chondrocyte damage. Circ-IQGAP1 might act as a new target for the treatment of OA.

Xi P ，Zhang CL ，Wu SY ，Liu L ，Li WJ ，Li YM ... -  《-》

Circ_DHRS3 positively regulates GREM1 expression by competitively targeting miR-183-5p to modulate IL-1β-administered chondrocyte proliferation, apoptosis and ECM degradation.

Osteoarthritis (OA) is a chronic inflammatory disease caused by degenerative changes of articular cartilage, involving in the expression changes of special circular RNAs (circRNAs). This study aimed to explore the role of circ_DHRS3 in OA cell models and provide a potential mechanism. OA cell models were constructed using human chondrocytes with Interleukin-1 beta (IL-1β) treatment. The expression of circ_DHRS3, microRNA (miR)-183-5p and Gremlin 1 (GREM1) mRNA was detected using real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation was identified using 3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide (MTT) assay. Cell apoptosis was investigated using flow cytometry assay. The protein levels of proliferation- and apoptosis-related proteins were quantified by western blot. The levels of extracellular matrix (ECM)-associated proteins were quantified by western blot to assess ECM degradation. The relationship between miR-183-5p and circ_DHRS3 or GREM1 was predicted and then verified by dual-luciferase reporter assay. Circ_DHRS3 expression was elevated in OA cartilage tissues and IL-1β-treated chondrocytes. Circ_DHRS3 was resistant to RNase R and Actinomycin D. Circ_DHRS3 knockdown promoted chondrocyte proliferation inhibited by IL-1β, and alleviated IL-1β-induced apoptosis and ECM degradation, which were reversed by the inhibition of miR-183-5p, a target of circ_DHRS3. MiR-183-5p restoration also enhanced IL-1β-blocked cell proliferation, and relieved IL-1β-induced cell apoptosis and ECM degradation, while GREM1 (a target of miR-183-5p) overexpression abolished the effects of miR-183-5p restoration. Moreover, circ_DHRS3 regulated GREM1 expression by targeting miR-183-5p. Circ_DHRS3 mediated IL-1β-administered chondrocyte proliferation, apoptosis and ECM degradation by positively regulating GREM1 expression via competitively targeting miR-183-5p.

Jiang R ，Gao H ，Cong F ，Zhang W ，Song T ，Yu Z ... -  《-》

Exosome-mediated circ_0001846 participates in IL-1β-induced chondrocyte cell damage by miR-149-5p-dependent regulation of WNT5B.

Osteoarthritis (OA) is the leading cause of physical disability in middle-aged and elderly people globally. Previous studies have revealed that circular RNA (circRNA) is involved in the pathogenesis of OA. In this study, we studied the role of circ_0001846 in interleukin-1β (IL-1β)-induced OA progression. Twenty-one patients with OA and 17 volunteers were recruited for the collection of articular cartilage tissues. The expression of circ_0001846, microRNA-149-5p (miR-149-5p) and Wingless-type MMTV integration site family, member 5B (WNT5B) was detected by quantitative real-time polymerase chain reaction. The protein expression was determined by western blot analysis. Cell viability, apoptosis, invasion and migration were demonstrated by cell counting kit-8, flow cytometry analysis, transwell invasion and wound-healing assays, respectively. The levels of IL-6 and tumor necrosis factor-α were detected by Enzyme-linked immunosorbent assay. The interaction between miR-149-5p and circ_0001846 or WNT5B was predicted by starbase online database, and proved by dual-luciferase reporter and RIP assays. Circ_0001846 and WNT5B expression were upregulated, while miR-149-5p expression was downregulated in articular cartilage tissues from patients with OA and IL-1β-treated CHON-001 cells compared with normal articular cartilage tissues or untreated CHON-001 cells. Circ_0001846 expression was increased in IL-1β-treated CHON-001 cell exosomes. Circ_0001846 knockdown reversed IL-1β-mediated cell proliferation, apoptosis, migration, invasion, inflammation and extracellular matrix (ECM) degradation in CHON-001 cells. Additionally, circ_0001846 participated in IL-1β-induced chondrocyte cell damage by sponging miR-149-5p. MiR-149-5p mediated IL-1β-induced chondrocyte cell dysfunction by targeting WNT5B. Furthermore, circ_0001846 secretion was mediated by exosomes in IL-1β-treated CHON-001 cells. Exosome-mediated transfer of circ_0001846 modulated IL-1β-induced chondrocyte cell damage by miR-149-5p/WNT5B axis, providing a novel avenue for the therapy of OA.

Zhu C ，Shen K ，Zhou W ，Wu H ，Lu Y ... -  《-》

Circ_0134111 knockdown relieves IL-1β-induced apoptosis, inflammation and extracellular matrix degradation in human chondrocytes through the circ_0134111-miR-515-5p-SOCS1 network.

Osteoarthritis (OA) is characterized by chondrocyte injury and dysfunction, such as excessive apoptosis, inflammatory response and extracellular matrix (ECM) degradation. Circular RNA (circRNA) deregulation is reported to be involved in OA. Our study aimed to explore the role of circ_0134111 in OA. Human chondrocytes were treated with interleukin-1β (IL-1β) to mimic OA cell model. The expression of circ_0134111, miR-515-5p and suppressor of cytokine signaling 1 (SOCS1) mRNA was measured by real-time quantitative polymerase chain reaction (RT-qPCR), and the protein levels of SOCS1 and apoptosis-/inflammation-/ECM-related markers were determined by western blot. Cell proliferation and cell apoptosis were assessed using cell counting kit-8 (CCK-8) and flow cytometry assay, respectively. For mechanism analysis, the predicted interaction between miR-515-5p and circ_0134111 or SOCS1 was verified by dual-luciferase reporter assay, pull-down assay and RNA immunoprecipitation (RIP) assay. Rescue experiments were performed to explore the interplay between miR-515-5p and circ_0134111 or SOCS1. Circ_0134111 was overexpressed in OA cartilage tissues and IL-1β-induced chondrocytes. IL-1β-induced chondrocyte apoptosis, inflammatory responses and ECM degradation were alleviated by circ_0134111 knockdown or miR-515-5p restoration. Circ_0134111 acted as miR-515-5p sponge to regulate miR-515-5p expression, and miR-515-5p deficiency reversed the effects of circ_0134111 knockdown in IL-1β-induced chondrocytes. MiR-515-5p directly bound to SOCS1, and circ_0134111 decoyed miR-515-5p to increase SOCS1 level. MiR-515-5p restoration alleviated IL-1β-induced chondrocyte apoptosis, inflammatory responses and ECM degradation, While SOCS1 overexpression partly abolished these effects. Circ_0134111 knockdown alleviated apoptosis, inflammatory responses and ECM degradation in OA cell model by mediating the miR-515-5p-SOCS1 network, hinting that circ_0134111 was involved in OA progression.

Wu R ，Zhang F ，Cai Y ，Long Z ，Duan Z ，Wu D ，Zhou Y ，Wang Q ... -  《-》

Knockdown of circ-PRKCH alleviates IL-1β-treated chondrocyte cell phenotypic changes through modulating miR-502-5p/ADAMTS5 axis.

Liu Z ，Cao J ，Zhang L ，Li J ，Yan T ，Zhou P ，Zhang S ... -  《-》