The Role of MicroRNA-381 in Chondrogenesis and Interleukin-1-β Induced Chondrocyte Responses

Background/Aims: Osteoarthritis (OA) is one of the most common chronic degenerative diseases. Many studies have demonstrated the role of microRNAs (miRNAs) in OA; however, the role of miR-302b in OA remains elusive. The aim of this study was to identify the role of miR-302b in LPS-induced injury in chondrocytes. Methods: Human OA chondrocytes (C28/12 cell line) were transfected with miR-302b inhibitor and miR-302b mimic to investigate the effects of miR-302b expression on chondrocyte apoptosis and inflammation, and to identify the miR-302b target proteins. Results: LPS treatment of chondrocytes significantly reduced cell viability and increased apoptotic rate. LPS treatment also increased the expression of inflammatory cytokines compared to control. miR-302b was up-regulated in LPS-induced chondrocytes. miR-302b was either suppressed or overexpressed in LPS-induced chondrocytes by transient transfection. miR-302b mimic transfection accelerated the effects of LPS on cell viability, apoptosis and inflammation. Of contrast, miR-302b inhibition represented a reverse effect. Dual luciferase activity demonstrated that Smad3 is a direct target for miR-302b and its expression was negatively regulated by miR-302b. In addition, miR-302b inhibition suppressed inflammation in LPS treated chondrocytes by up-regulating Smad3 expression. Moreover, LPS induced down-regulation of Notch and mTOR signaling pathway-related protein expressions, and miR-302b inhibition increased the expressions of Notch and mTOR signaling pathway-related proteins. We further found that miR-302b negatively regulated Notch2 levels through direct targeting its 3’UTR. Conclusions: These results suggest that miR-302b suppression may function as a protector in suppressing the inflammation during the development and progression of OA by up-regulating the target Smad3 expression.

Section: Discussionmentioning

confidence: 99%

Knockdown MiR-302b Alleviates LPS-Induced Injury by Targeting Smad3 in C28/I2 Chondrocytic Cells

Wang

Jin

et al. 2018

“…Studied have indicated that miRNAs have an important role in the process of chondrogenesis and cartilage remodeling [9]. The aberrant miRNA expression profiles have been demonstrated to be associated with OA [10,11], and miRNAs acted as important regulators in OA development, as well as participated in inflammatory response [12,13]. Previous studies have demonstrated that many miRNAs were involved in the regulation of OA, such as miR-320, miR-21, and miR-140 [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

MiR-146a Aggravates LPS-Induced Inflammatory Injury by Targeting CXCR4 in the Articular Chondrocytes

Sun

Song

et al. 2017

Key WordsInflammatory injury • MicroRNA-146a • C-X-C chemokine receptor type 4 • PI3K/AKT • Wnt/β-catenin Abstract Background/Aims: Osteoarthritis (OA) as a degenerative disease is a major problem in ageing populations. To better understand the molecular mechanisms in the pathogenesis of OA, this study explored the role of microRNA (miR)-146a in the articular chondrocytes. Methods: The articular chondrocyte line ATDC5 was used to simulate inflammatory injury by LPS administration in vitro. Cell viability, apoptosis, mRNA expressions and productions of inflammatory factors were assessed, respectively. Mir-146a and Cxcr4 mRNA expressions were measured by qRT-PCR. Targeting effect of miR-146a on Cxcr4 3'UTR was assessed by luciferase activity analysis. Protein expression levels of CXCR4 and main factors in PI3K/AKT, Wnt/β-catenin signal pathways were measured by western blotting. Results: LPS exposure suppressed cell viability, prompted apoptosis of ATDC5 cells, and stimulated expression and release of inflammatory factors. MiR-146a was upregulated in LPS-induced cells. Overexpression of miR146a further aggravated LPS-induced inflammatory injury, while it was reduced after miR146a was knocked down. CXCR4 expression was negatively regulated by miR-146a. CXCR4 was a direct target of miR-146a and thus involved in regulatory effect of miR-146a on the injured chondrocytes, which was also related with phosphorylation levels of PI3K/AKT and expressions of Wnt/β-catenin signal factors. Conclusion: miR-146a promoted inflammatory response of articular chondrocytes via targeting CXCR4 and suppressing CXCR4 expression. Overexpression of CXCR4 could attenuate the inflammatory injury. Our findings provided novel evidence which might be useful for further studies exploring therapeutic approaches for OA via targeting miR-146a.

“…In our study, we used H 2 O 2 to establish cell apoptosis model and assessed the potential antiapoptotic effect of gAPN on the H 2 O 2 -induced chondrocyte apoptosis in vitro. Because OA chondrocyte behavior and phenotypes can be affected by the surrounding matrix state, culture methods, and passage numbers [47,48], these behavior and phenotypes might contribute to the difference of gAPN-induced responses in each study. Another possibility may be due to the different dosage of gAPN selected in experiments.…”

Section: Ampk/mtor Signaling Pathway Is Involved In Gapn-induced Automentioning

confidence: 99%

Globular Adiponectin Attenuated H2O2-Induced Apoptosis in Rat Chondrocytes by Inducing Autophagy Through the AMPK/ mTOR Pathway

Cui

Ding

et al. 2017

Background/Aims: Chondrocyte apoptosis is closely related to the development and progression of osteoarthritis. Global adiponectin (gAPN), secreted from adipose tissue, possesses potent anti-inflammatory and antiapoptotic properties in various cell types. This study aimed to investigate the role of autophagy induced by gAPN in the suppression of H 2 O 2 -induced apoptosis and the potential mechanism of gAPN-induced autophagy in chondrocytes. Methods: H 2 O 2 was used to induce apoptotic injury in rat chondrocytes. CCK-8 assay was performed to determine the viability of cells treated with different concentrations of gAPN with or without H 2 O 2 . Cell apoptosis was detected by flow cytometry and TUNEL staining. Mitochondrial membrane potential was examined using JC-1 fluorescence staining assay. The autophagy inhibitors 3-MA and Bafilomycin A1 were used to treat cells and then evaluate the effect of gAPN-induced autophagy. To determine the downstream pathway, chondrocytes were preincubated with the AMPK inhibitor Compound C. Beclin-1, LC3B, P62 and apoptosisrelated proteins were identified by Western blot analysis. Results: H 2 O 2 (400 μM)-induced chondrocytes apoptosis and caspase-3 activation were attenuated by gAPN (0.5 μg/mL). gAPN increased Bcl-2 expression and decreased Bax expression. The loss of mitochondrial membrane potential induced by H 2 O 2 was also abolished by gAPN. Furthermore, the antiapoptotic effect of gAPN was related to gAPN-induced autophagy by increased formation of Beclin-1 and LC3B and P62 degradation. In particular, the inhibition of gAPN-induced autophagy by 3-MA prevented the protective effect of gAPN on apoptosis induced by H 2 O 2 . Moreover, gAPN increased p-AMPK expression and decreased p-mTOR expression. Compound C partly suppressed the expression of autophagy-related proteins and restored the expression of p-mTOR suppressed by gAPN. Thus, the AMPK/mTOR pathway played an important role