Circular RNA CSNK1G1 promotes the progression of osteoarthritis by targeting the miR‑4428/FUT2 axis

Circ-PDE1C/miR-766-3p/SGTB axis regulates the IL-1β-induced apoptosis, inflammation and oxidative stress in human chondrocytes

BACKGROUND

Osteoarthritis (OA) is a common degenerative joint disease. Circular RNA Phosphodiesterase 1 C (circ-PDE1C, hsa_circ_0134111) has participated in the IL-1β-induced chondrocyte damages. The objective of our study was to explore the molecular mechanism of circ-PDE1C.

METHODS

Circ-PDE1C, microRNA-766-3p (miR-766-3p) or Small Glutamine Rich Tetratricopeptide Repeat Co-Chaperone Beta (SGTB) expression was determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cell counting kit-8 (CCK-8) assay and flow cytometry were used to analyze proliferation and apoptosis, respectively. Western blotting assay was performed for protein detection. The inflammatory cytokines were measured by Enzyme-linked immunosorbent assay (ELISA). Oxidative stress was assessed by commercial kits. Target analysis was conducted by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay.

RESULTS

Circ-PDE1C was abnormally overexpressed in OA tissues and IL-1β-exposed chondrocytes. Downregulation of circ-PDE1C alleviated the IL-1β-induced cell apoptosis, inflammation, extracellular matrix degradation and oxidative stress. Circ-PDE1C could interact with miR-766-3p to serve as miRNA sponge. The function of si-circ-PDE1C was attributed to the inhibition of miR-766-3p. Additionally, miR-766-3p directly targeted the 3'UTR of SGTB. The miR-766-3p upregulation impeded the IL-1β-triggered cell damages through reducing the level of SGTB. Moreover, SGTB expression was regulated by circ-PDE1C via binding to miR-766-3p in IL-1β-induced chondrocytes.

CONCLUSION

Altogether, circ-PDE1C enhanced the IL-1β-induced dysfunction in chondrocytes via upregulating SGTB by targeting miR-766-3p.

Circular RNA SLTM as a miR-421-competing endogenous RNA to mediate HMGB2 expression stimulates apoptosis and inflammation in arthritic chondrocytes

Osteoarthritis (OA) is the most common age-related joint disease characterized by chronic inflammation, progressive articular cartilage destruction, and subchondral sclerosis. Accumulating evidence suggests that circular RNAs (circRNAs) play key roles in OA, but the function of circSLTM in OA remains greatly unknown. Therefore, this study focused on interleukin-1β (IL-1β)-treated primary human chondrocytes as well as a rat model to investigate the expression pattern and functional role of circSLTM in OA in vitro and in vivo. CircSLTM and high mobility group protein B2 (HMGB2) were upregulated in IL-1β-induced chondrocytes, whereas miR-421 was downregulated. Knockdown of circSLTM or overexpression of miR-421 ameliorated IL-1β-induced chondrocyte apoptosis and inflammation. The regulatory relationship between circSLTM and miR-421, as well as that between miR-421 and HMGB2, was predicted by bioinformatics and then verified by the RNA immunoprecipitation experiment and dual-luciferase reporter gene assay. Furthermore, silencing of circSLTM increased cartilage destruction and decreased cartilage tissue apoptosis rate and inflammation in a rat model of OA. Taken together, our findings demonstrate the fundamental role of circSLTM in OA progression and provide a potential molecular target for OA therapy.

Circ_0136474 promotes the progression of osteoarthritis by sponging mir-140-3p and upregulating MECP2

BACKGROUND

Circular RNAs (circRNAs) have pivotal roles in the progression of many diseases, including osteoarthritis (OA). The detained function and regulatory mechanism of circ_0136474 in OA are still largely unknown.

METHODS

The chondrocytes (CHON-001 cells) were exposed to interleukin-1 beta (IL-1β) to mimic the injury in OA. The expression levels of circ_0136474, microRNA-140-3p (miR-140-3p), methyl-CpG-binding protein 2 (MECP2) mRNA were measured by qRT-PCR. Cell proliferation was assessed using CCK-8 assay. Flow cytometry was employed for measuring cell apoptosis. All protein levels were evaluated via western blot analysis. ELISA was used for detecting the concentrations of the inflammatory cytokines. Dual-luciferase reporter analysis and RNA Immunoprecipitation analysis were conducted for confirming the association between miR-140-3p and circ_0136474 or MECP2.

RESULTS

Circ_0136474 was upregulated in IL-1β-induced CHON-001 cells and OA cartilage tissues. Circ_0136474 deficiency alleviated IL-1β-stimulated CHON-001 cell damage via enhancing cell proliferation and reducing extracellular matrix (ECM) degradation, apoptosis, and inflammation. Circ_0136474 was a sponge of miR-140-3p, and miR-140-3p inhibition reversed the roles of circ_0136474 knockdown in IL-1β-treated CHON-001 cells. Moreover, miR-140-3p directly targeted MECP2, and upregulation of miR-140-3p attenuated L-1β-triggered CHON-001 cell injury via targeting MECP2. Additionally, circ_0136474 regulated MECP2 level via sponging miR-140-3p.

CONCLUSION

Circ_0136474 knockdown alleviated IL-1β-triggered CHON-001 cell damage through modulation of miR-140-3p/MECP2 axis, indicating a new target for treatment of OA.

Circular RNA RHOT1 Regulates miR-142-5p/CCND1 to Participate in Chondrocyte Autophagy and Proliferation in Osteoarthritis

Background

Osteoarthritis (OA) serves as one of the most prevalent types of joint disorders and is a leading cause of symptoms of stiffness, swelling, and arthralgia. Circular RNAs (circRNAs) have been reported to participate in various cellular processes by competing with microRNAs. Meanwhile, cyclinD1 (CCND1) is a key cell cycle regulatory protein and plays a crucial role in OA progression. Nevertheless, the function of circRHOT1 in the modulation of OA progression is still obscure. Here, we explored the effect of circRHOT1 on autophagy and extracellular matrix (ECM) in OA.

Methods

The expression of circRHOT1 and autophagy markers was detected in OA samples. The effect of circRHOT1 on OA was analyzed in the OA rat model. The function of circRHOT1 in the regulation of OA was assessed by CCK-8, colony formation, flow cytometry analysis, quantitative real-time PCR, Western blot analysis, and luciferase reporter gene assay in chondrocytes.

Results

We observed that autophagy markers, including LC3 and beclin1, were repressed in clinical OA samples. The expression of circRHOT1 and CCND1 was induced but the miR-142-5p expression was reduced in clinical OA samples. The miR-142-5p expression was negatively correlated with circRHOT1 and CCND1, and the circRHOT1 expression was positively associated with CCND1 in clinical OA samples. Meanwhile, the apoptosis was induced in OA rats but the depletion of circRHOT1 could block the phenotype in the rats. The articular cartilage degeneration was promoted in OA rats, while the knockdown of circRHOT1 repressed the degeneration. The serum levels of CTX-II and COMP were increased in OA rats, and the silencing of circRHOT1 downregulated levels of these proteins. In addition, the expression of collagen II and aggrecan was promoted by the depletion of circRHOT1 in the OA rats. Significantly, the expression of LC3 and beclin1 was suppressed in OA rats, in which the knockdown of circRHOT1 could reverse the effect. Moreover, the depletion of circRHOT1 repressed the cell viability and proliferation but induced apoptosis of chondrocytes. The expression levels of LC3, beclin1, collagen II, and aggrecan were induced by circRHOT1 knockdown. Mechanically, circRHOT1 was able to enhance the CCND1 expression by sponging miR-142-5p in chondrocytes. The overexpression of CCND1 or the inhibition of miR-142-5p reversed circRHOT1 depletion-mediated chondrocyte phenotypes.

Conclusions

Circular RNA RHOT1 enhances the CCND1 expression by sponging miR-142-5p to inhibit chondrocyte autophagy and promote chondrocyte proliferation in osteoarthritis. Our findings provided a promising therapeutic target for OA.

YY1 and eIF4A3 are mediators of the cell proliferation, migration and invasion in cholangiocarcinoma promoted by circ-ZNF609 by targeting miR-432-5p to regulate LRRC1

Cholangiocarcinoma is a highly aggressive malignant tumor, and its incidence is increasing all over the world. More and more evidences show that the aberrant expression of circular RNAs play important roles in tumorigenesis and progression. Current studies on the expression and function of circRNAs in cholangiocarcinoma are scarce. In this study, circ-ZNF609 was discovered as a novel circRNA highly expressed in cholangiocarcinoma for the first time. The circ-ZNF609 expression is connected with the advanced TNM stage, lymphatic invasion and survival time in cholangiocarcinoma patients, and can be used as an independent prognostic factor for the patients. Circ-ZNF609 can promote the cholangiocarcinoma cells proliferation, migration and invasion in vitro, it can also catalyze the xenograft growth in vivo. The promoting effect of circ-ZNF609 on cholangiocarcinoma is achieved via oncogene LRRC1 up-regulation through targeting miR-432-5p by endogenous competitive RNA mechanism. In addition, transcription factor YY1 can bind to the promoter of ZNF609 to further facilitate the transcription of circ-ZNF609. RNA binding protein eIF4A3 can bind to the pre-mRNA of circ-ZNF609 which promotes the circ-ZNF609 circular formation. Overall, YY1/eIF4A3/circ-ZNF609/miR-432-5p/LRRC1 have a significant role in progression of cholangiocarcinoma, and circ-ZNF609 is expected to become a novel biomarker for targeted therapy and prognosis evaluation of cholangiocarcinoma.

Recent Advances in Pharmacological Intervention of Osteoarthritis: A Biological Aspect

Osteoarthritis (OA) is a degenerative joint disease in the musculoskeletal system with a relatively high incidence and disability rate in the elderly. It is characterized by the degradation of articular cartilage, inflammation of the synovial membrane, and abnormal structure in the periarticular and subchondral bones. Although progress has been made in uncovering the molecular mechanism, the etiology of OA is still complicated and unclear. Nevertheless, there is no treatment method that can effectively prevent or reverse the deterioration of cartilage and bone structure. In recent years, in the field of pharmacology, research focus has shifted to disease prevention and early treatment rather than disease modification in OA. Biologic agents become more and more attractive as their direct or indirect intervention effects on the initiation or development of OA. In this review, we will discuss a wide spectrum of biologic agents ranging from DNA, noncoding RNA, exosome, platelet-rich plasma (PRP), to protein. We searched for key words such as OA, DNA, gene, RNA, exosome, PRP, protein, and so on. From the pharmacological aspect, stem cell therapy is a very special technique, which is not included in this review. The literatures ranging from January 2016 to August 2021 were included and summarized. In this review, we aim to help readers have a complete and precise understanding of the current pharmacological research progress in the intervention of OA from the biological aspect and provide an indication for the future translational studies.

New perspectives on the roles of circular RNAs in osteoarthritis development and progression (Review)

Osteoarthritis (OA) is a common disease of the elderly, posing a major personal and socioeconomic burden. OA is characterized by painful degeneration of articular cartilage, and its prevention, diagnosis and treatment remain problematic. Circular RNAs (circRNAs) constitute a large family of non-coding RNAs that are widely distributed, stable, conserved and tissue-specific. circRNAs have been found to be closely associated with OA development and progression, and they may serve as targets for disease prevention and treatment. The aim of the present article was to review the roles of circRNAs in OA and discuss possible treatment strategies.

Circular RNA hsa_circ_0005567 overexpression promotes M2 type macrophage polarization through miR-492/SOCS2 axis to inhibit osteoarthritis progression

Synovial macrophage polarization is essential for osteoarthritis (OA) development. Our study aims to investigate the underlying function and the molecular mechanisms of hsa_circ_0005567 in macrophage polarization. Circular RNA (CircRNA), microRNA (miRNA), and mRNA expression levels were detected by quantitative reverse transcription polymerase chain reaction (RT-qPCR). RNA pull down, luciferase reporter were employed to test the interaction between miR-492 and hsa_circ_0005567/suppressors of cytokine signaling 2 (SOCS2). Ectopic overexpression was used to evaluate the function of hsa_circ_0005567. The supernatant of THP-1 cells was used to incubate chondrocytes. Cell Counting Kit-8 (CCK-8) and flow cytometry were conducted to determine cell viability, proportion of M1 or M2 macrophages and apoptotic rate. The results showed that the hsa_circ_0005567 expression level was downregulated in the synovial tissues of osteoarthritis patients. Overexpression of hsa_circ_0005567 inhibited M1 macrophage polarization, and promoted M2 macrophage polarization. Hsa_circ_0005567 was proved to be a molecular sponge for miR-492, and SOCS2 was verified as the target of miR-492. MiR-492 mimic could reverse the effect of hsa_circ_0005567 overexpression on macrophage polarization. Besides, the supernatant from LPS-treated THP-1 macrophage significantly decreased chondrocytes cell viability and increased cell apoptosis ratio, which was reversed by hsa_circ_0005567 overexpression. In conclusion, hsa_circ_0005567 overexpression promoted M2 macrophage polarization through miR-492/SOCS2 axis to reduced chondrocyte apoptosis, which could inhibit osteoarthritis progression.

Fucosyltransferase 2 inhibitors: Identification via docking and STD-NMR studies

Fucosyltransferase 2 (FUT2) catalyzes the biosynthesis of A, B, and H antigens and other important glycans, such as (Sialyl Lewisx) sLex, and (Sialyl Lewisy) sLey. The production of these glycans is increased in various cancers, hence to design and develop specific inhibitors of FUT2 is a therapeutic strategy. The current study was designed to identify the inhibitors for FUT2. In silico screening of 300 synthetic compounds was performed. Molecular docking studies highlighted the interactions of ligands with critical amino acid residues, present in the active site of FUT2. The epitope mapping in ligands was performed using the STD-NMR experiments to identify the interactions between ligands, and receptor protein. Finally, we have identified 5 lead compounds 4, 5, 26, 27, and 28 that can be studied for further development as cancer therapeutic agents.

Studies on the Role of circRNAs in Osteoarthritis

Objective

Provide a reference to elucidate the mechanism of circRNAs regulating osteoarthritis (OA) and the clinical treatment.

Methods

Herein, articles about circRNAs (hsa-circ) and osteoarthritis in the recent 5 years have been reviewed and the differential expression and regulatory effect of circRNAs in OA deduced. Based on these conclusions and Protein-Protein Interaction (PPI), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of the acquired circRNAs, the potential functions and interactions of circRNAs in OA and the involved signaling pathways are discussed.

Results

A total of 33 studies meeting the inclusion criteria were included in this study, and 27 circRNAs were upregulated and 8 circRNAs were downregulated in OA. A total of 31 circRNAs were finally included in the PPI, GO, and KEGG analyses. From PPI, 12 map nodes and 7 map edges were interrelated. VWF had the biggest node and edge size. From GO, VWF showed a majority of the functions. From KEGG, circRNAs are enriched in PI3K/AKT, human papillomavirus infection (HPI), and focal adhesion (FA) pathways, and VWF was involved in major pathways.

Conclusion

We found that most articles about circRNAs regulating OA in the recent 5 years focused on the mechanism, especially the absorption effect of circ-miRNA as sponges in the recent 2 years, while most of the articles about their functions addressed ECM and PI3K, AKT, and mTOR signaling pathways. Future studies might focus on the functions of circRNAs, and circRNA VWF, with preferable functions, interactions, and involvement, can be used as a biological indicator to detect OA in clinical practice.