Circular RNA circ_0128846 promotes the progression of osteoarthritis by regulating miR-127-5p/NAMPT axis

Identification of Key lncRNAs, circRNAs, and mRNAs in Osteoarthritis via Bioinformatics Analysis

Osteoarthritis (OA) is a common degenerative joint disorder that adversely affects the quality of life of patients. Identification of novel diagnostic biomarkers is pivotal for the early detection and prevention of OA. Dataset GSE185059 was selected from Gene Expression Omnibus database to obtain differentially expressed lncRNAs (DE-lncRNAs), mRNAs (DE-mRNAs), and circRNAs (DE-circRNAs) between OA and normal samples. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses as well as protein-protein interaction (PPI) network construction of DE-mRNAs were conducted. Hub genes were identified from PPI networks and validated by RT-qPCR. starBase database was utilized for predicting miRNAs binding with hub genes, selected DE-lncRNAs and DE-circRNAs, respectively. The competing endogenous RNA (ceRNA) networks were constructed. A total of 818 DE-mRNAs, 191 DE-lncRNAs, and 2053 DE-circRNAs were identified. The DE-mRNAs were significantly enriched in several inflammation-related GO terms and KEGG pathways such as positive regulation of cell-cell adhesion, TNF-alpha signaling pathway and NF-kappa B signaling pathway. Thirteen hub genes were identified, which were CFTR, GART, SMAD2, NCK1, TJP1, UBE2D1, EFTUD2, PRKACB, IL10, SNRPG, CHD4, RPS24, and SRSF6. OA-related DE-lncRNA/circRNA-miRNA-hub gene networks were constructed. We identified 13 hub genes and constructed the ceRNA networks related to OA, providing a theoretical basis for further research.

CircRNAs in osteoarthritis: research status and prospect

Osteoarthritis (OA) is the most common joint disease globally, and its progression is irreversible. The mechanism of osteoarthritis is not fully understood. Research on the molecular biological mechanism of OA is deepening, among which epigenetics, especially noncoding RNA, is an emerging hotspot. CircRNA is a unique circular noncoding RNA not degraded by RNase R, so it is a possible clinical target and biomarker. Many studies have found that circRNAs play an essential role in the progression of OA, including extracellular matrix metabolism, autophagy, apoptosis, the proliferation of chondrocytes, inflammation, oxidative stress, cartilage development, and chondrogenic differentiation. Differential expression of circRNAs was also observed in the synovium and subchondral bone in the OA joint. In terms of mechanism, existing studies have mainly found that circRNA adsorbs miRNA through the ceRNA mechanism, and a few studies have found that circRNA can serve as a scaffold for protein reactions. In terms of clinical transformation, circRNAs are considered promising biomarkers, but no large cohort has tested their diagnostic value. Meanwhile, some studies have used circRNAs loaded in extracellular vesicles for OA precision medicine. However, there are still many problems to be solved in the research, such as the role of circRNA in different OA stages or OA subtypes, the construction of animal models of circRNA knockout, and more research on the mechanism of circRNA. In general, circRNAs have a regulatory role in OA and have particular clinical potential, but further studies are needed in the future.

CircRNA-mediated ceRNA mechanism in Osteoarthritis: special emphasis on circRNAs in exosomes and the crosstalk of circRNAs and RNA methylation

Osteoarthritis (OA) is an age-related joint disease with chronic inflammation, progressive articular cartilage destruction and subchondral bone sclerosis. CircRNAs (circRNAs) are a class of non-coding RNA with a circular structure that participate in a series of important pathophysiological processes of OA, especially its ceRNA mechanisms, and play an important role in OA. CircRNAs may be potential biomarkers for the diagnosis and prognosis of OA. Additionally, differentially expressed circRNAs were found in patients with OA, indicating that circRNAs are involved in the pathogenesis of OA. Experiments have shown that the intra-articular injection of modified circRNAs can effectively relieve OA. Exosomal circRNAs and methylated circRNAs also provide new ideas for the treatment of OA. Clarifying the important roles of circRNAs in OA will deepen people's understanding of the pathogenesis of OA. CircRNAs may be developed as new biomarkers or drug targets for the diagnosis of OA and provide new methods for the treatment of OA.

Osteoarthritis year in review: genetics, genomics and epigenetics

This "year in review" provides a summary of the research findings on the topic of genetics, genomics and epigenetics for osteoarthritis (OA) between Mar 2021-Apr 2022. A search routine of the literature in PubMed for the keyword, osteoarthritis, together with topics on genetics, genomics, epigenetics, polymorphism, DNA methylation, noncoding RNA, lncRNA, proteomics, and single cell RNA sequencing, returned key research articles and relevant reviews. Following filtering of duplicates across search routines, 695 unique research articles and 112 reviews were identified. We manually curated these articles and selected 90 as references for this review. However, we were unable to refer to all these articles, and only used selected articles to highlight key outcomes and trends. The trend in genetics is on the meta-analysis of existing cohorts with comparable genetic and phenotype characterisation of OA; in particular, clear definition of endophenotypes to enhance the genetic power. Further, many researchers are realizing the power of big data and multi-omics approaches to gain molecular insights for OA, and this has opened innovative approaches to include transcriptomics and epigenetics data as quantitative trait loci (QTLs). Given that most of the genetic loci for OA are not located within coding regions of genes, implying the impact is likely to be on gene regulation, epigenetics is a hot topic, and there is a surge in studies relating to the role of miRNA and long non-coding RNA on cartilage biology and pathology. The findings are exciting and new insights are provided in this review to summarize a year of research and the road map to capture all new innovations to achieve the desired goal in OA prevention and treatment.

Hsa_circ_0128846 knockdown attenuates the progression of pancreatic cancer by targeting miR-1270/NR3C1 axis

The considerable role of circular RNAs (circRNAs) make them prospective biomarkers in cancer therapy. Our study aimed to unveil the function of circ_0128846 in pancreatic cancer (PC). The expressions of circ_0128846, miR-1270 and NR3C1 mRNA were measured via RT-qPCR. The expressions of NR3C1 protein and apoptosis-related markers (Bax and Bcl-2) were measured via western blotting. CCK-8, colony-forming, or wound healing assay was respectively utilized to identify cell proliferation, growth and migration. Xenograft model was developed to evaluate tumor growth affected by circ_0128846 in vivo. The putative binding between miR-1270 and circ_0128846 or NR3C1 was testified by dual-luciferase reporter, RIP or pull-down assay. Circ_0128846 showed elevated expression in PC. Circ_0128846 deficiency restrained cancer cell proliferation, colony formation and migratory ability, enhanced cell apoptotic rate, and also impeded tumor development in vivo. Circ_0128846 directly targeted miR-1270 whose expression was declined in PC. The suppressive effects of silencing circ_0128846 on PC cell malignant phenotypes were largely reversed by miR-1270 inhibition. NR3C1 was targeted by miR-1270 and was highly regulated in PC. The repressive effects of NR3C1 knockdown on PC cell malignant phenotypes were partly abolished by miR-1270 inhibition. Circ_0128846 deficiency blocked PC progression via mediating the miR-1270/NR3C1 pathway, which partly illustrated PC pathogenesis.

Circular RNA_0003800 exacerbates IL-1β-induced chondrocyte injury via miR-197-3p/SOX5 axis

BACKGROUND

Osteoarthritis (OA) is a serious degenerative disease of articular cartilage, which has a great impact on the quality of life of patients. Circular RNA (circRNA) plays an important role in OA progression. Our study aims to explore the role and mechanism of circ_0003800 in OA.

METHODS

Circ_0003800, microRNA-197-3p (miR-197-3p) and SRY-box transcription factor 5 (SOX5) contents were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. Cell Counting Kit-8 (CCK8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, western blot and enzyme-linked immunosorbent assay (ELISA) were deployed to evaluate cell proliferation, apoptosis, extracellular matrix (ECM) degradation, inflammatory response and oxidative stress. Interaction of miR-197-3p and circ_0003800 or SOX5 was evidenced by dual-luciferase reporter system, RNA immunoprecipitation (RIP) and RNA pull down assays.

RESULTS

OA tissues and model cells had higher abundance of circ_0003800 and SOX5, while miR-197-3p content was lower. Functionally, circ_0003800 knockdown alleviated IL-1β-mediated injury in C28/I2 cells. Mechanistically, circ_0003800 could sponge miR-197-3p, and miR-197-3p could target SOX5. Besides, in-miR-197-3p reversed the suppressive effect of circ_0003800 downregulation on IL-1β-induced C28/I2 cell injury, and SOX5 overexpression could also diminish the inhibitory effect of miR-197-3p on IL-1β-induced C28/I2 cell injury.

CONCLUSION

Circ_0003800 exacerbates IL-1β-induced chondrocyte injury via miR-197-3p/SOX5 axis.

Recent advancements of miRNAs in the treatment of bone diseases and their delivery potential

Advances in understanding miRNAs as endogenous posttranscriptional regulatory units have projected them as novel therapeutics for several untreatable diseases. miRNAs are endogenous non-coding small single-stranded RNA molecules (20-24 nucleotides) with specific gene regulatory functions like repression of mRNA translation by degrading mRNAs. Emerging evidence suggests the role of miRNAs in various stages of bone growth and development. Undoubtedly, due to their critical role in bone remodeling, miRNAs might be projected as a novel approach to treating bone-related diseases. However, the instability associated with miRNAs in their complex environment, such as degradation by nucleases, is a concern. Thus, recent attention is being paid to maintaining the miRNAs' safety and efficacy in the cells. Various efficient delivery systems and chemical modifications of miRNAs are being developed to make them a potential therapeutic option for bone diseases. Here, we have tried to recapitulate the recent advances in the role of miRNAs in bone disease, along with the potential delivery systems for their efficient delivery to the cells.

Mechanism of miR-34a in the metabolism of extracellular matrix in fibroblasts of stress urinary incontinence via Nampt-mediated autophagy

Stress urinary incontinence (SUI) is a troublesome hygienic problem that afflicts the female population and is associated with extracellular matrix (ECM). Herein, we investigated the effects of microRNA (miR)-34a on ECM metabolism in fibroblasts of SUI via mediating nicotinamide phosphoribosyl transferase (Nampt/NAmPRTase) and hope to find novel insights in the treatment of SUI. Firstly, the anterior vaginal wall tissues of SUI patients and the female vaginal wall fibroblasts (FVWFs) of non-SUI subjects were collected and identified. Then, FVWFs were treated with 10 ng/mL of interleukin 1 beta (IL-1β) to establish SUI cell models. Subsequently, miR-34a and Nampt expressions in both types of cells were detected via RT-qPCR. It was found that miR-34a was poorly expressed, while Nampt was highly expressed in SUI. Subsequently, IL-1β-treated FVWFs were transfected with miR-34a-mimic and pcDNA3.1-Nampt, respectively. Thereafter, RT-qPCR and Western blot detected that miR-34a overexpression increased COL1A, ACAN, and TIMP-1; decreased MMP-2 and MMP-9; and elevated LC3 II/I ratio, Beclin-1 expression, and the autophagosome number in IL-1β-treated FVWFs, while Nampt upregulation reversed the above outcomes. Then, dual-luciferase reporter gene assay detected that Nampt is a downstream target of miR-34a. Together, miR-34a overexpression promoted autophagy, inhibited ECM degradation in IL-1β-treated FVWFs, and ameliorated SUI via suppressing Nampt.

Expression Profile Analysis to Identify Circular RNA Expression Signatures in Muscle Development of Wu'an Goat Longissimus Dorsi Tissues

The growth and development of skeletal muscle is a physiological process regulated by a variety of genes and signaling pathways. As a posttranscriptional regulatory factor, circRNA plays a certain regulatory role in the development of animal skeletal muscle in the form of a miRNA sponge. However, the role of circRNAs in muscle development and growth in goats is still unclear. In our study, apparent differences in muscle fibers in Wu'an goats of different ages was firstly detected by hematoxylin-eosin (HE) staining, the circRNA expression profiles of longissimus dorsi muscles from 1-month-old (mon1) and 9-month-old (mon9) goats were screened by RNA-seq and verified by RT-qPCR. The host genes of differentially expressed (DE) circRNAs were predicted, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes analyses (KEGG) of host genes with DE circRNAs were performed to explore the functions of circRNAs. The circRNA-miRNA-mRNA networks were then constructed using Cytoscape software. Ten significantly differentially expressed circRNAs were also verified in the mon1 and mon9 groups by RT-qPCR. Luciferase Reporter Assay was used to verify the binding site between circRNA and its targeted miRNA. The results showed that a total of 686 DE circRNAs were identified between the mon9 and mon1 groups, of which 357 were upregulated and 329 were downregulated. Subsequently, the 467 host genes of DE circRNAs were predicted using Find_circ and CIRI software. The circRNA-miRNA-mRNA network contained 201 circRNAs, 85 miRNAs, and 581 mRNAs; the host mRNAs were associated with "muscle fiber development" and "AMPK signaling pathway" and were enriched in the FoxO signaling pathway. Competing endogenous RNA (ceRNA) network analysis showed that novel_circ_0005314, novel_circ_0005319, novel_circ_0009256, novel_circ_0009845, novel_circ_0005934 and novel_circ_0000134 may play important roles in skeletal muscle growth and development between the mon9 and mon1 groups. Luciferase Reporter Assay confirmed the combination between novel_circ_0005319 and chi-miR-199a-5p, novel_circ_0005934 and chi-miR-450-3p and novel_circ_0000134 and chi-miR-655. Our results provide specific information related to goat muscle development and a reference for the goat circRNA profile.

Single-cell transcriptome analysis reveals aberrant stromal cells and heterogeneous endothelial cells in alcohol-induced osteonecrosis of the femoral head

Alcohol-induced osteonecrosis of the femoral head (ONFH) is a disabling disease with a high incidence and elusive pathogenesis. Here, we used single-cell RNA sequencing to explore the transcriptomic landscape of mid- and advanced-stage alcohol-induced ONFH. Cells derived from age-matched hip osteoarthritis and femoral neck fracture samples were used as control. Our bioinformatics analysis revealed the disorder of osteogenic-adipogenic differentiation of stromal cells in ONFH and altered regulons such as MEF2C and JUND. In addition, we reported that one of the endothelial cell clusters with ACKR1 expression exhibited strong chemotaxis and a weak angiogenic ability and expanded with disease progression. Furthermore, ligand-receptor-based cell-cell interaction analysis indicated that ACKR1+ endothelial cells might specifically communicate with stromal cells through the VISFATIN and SELE pathways, thus influencing stromal cell differentiation in ONFH. Overall, our data revealed single cell transcriptome characteristics in alcohol-induced ONFH, which may contribute to the further investigation of ONFH pathogenesis.

Single-cell RNA-seq of bone from patients with osteonecrosis of the femoral head (ONFH) highlights the relevance of stromal and endothelial cells to disease pathogenesis, and provides a resource for developing cell type-specific therapeutic strategies.

Nampt promotes fibroblast extracellular matrix degradation in stress urinary incontinence by inhibiting autophagy

Stress urinary incontinence (SUI) is defined as involuntary urinary leakage happening in exertion. Nicotinamide phosphoribosyltransferase (Nampt) is seldom researched in the pathogenesis of SUI. Accordingly, the current study set out to elucidate the role of Nampt in SUI progression. Firstly, we determined Nampt expression patterns in SUI patients and rat models. In addition, fibroblasts were obtained from the anterior vaginal wall tissues of non-SUI patients and subjected to treatment with different concentrations of interleukin-1β (IL-1β), followed by quantification of Nampt expressions in fibroblasts. Subsequently, an appropriate concentration of IL-1β was selected to treat anterior vaginal wall fibroblasts. Nampt was further silenced in IL-1β-treated fibroblasts to assess the role of Nampt in autophagy and extracellular matrix (ECM) degradation. Lastly, functional rescue assays were carried out to inhibit autophagy and evaluate the role of autophagy in the mechanism of Nampt modulating IL-1β-treated fibroblast ECM degradation. It was found that Nampt was highly-expressed in SUI patients and rat models and IL-1β-treated fibroblasts. On the other hand, Nampt silencing was found to suppress ECM degradation and promote SUI fibroblast autophagy. Additionally, inhibition of autophagy attenuated the inhibitory effects of Nampt silencing on SUI fibroblast ECM degradation. Collectively, our findings revealed that Nampt was over-expressed in SUI, whereas Nampt silencing enhanced SUI fibroblast autophagy, and thereby inhibited ECM degradation.

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.