lnc-SAMD14-4 can regulate expression of the COL1A1 and COL1A2 in human chondrocytes

Aberrant methylation and expression of TNXB promote chondrocyte apoptosis and extracullar matrix degradation in hemophilic arthropathy via AKT signaling

Recurrent joint bleeding in hemophilia patients frequently causes hemophilic arthropathy (HA). Drastic degradation of cartilage is a major characteristic of HA, but its pathological mechanisms has not yet been clarified. In HA cartilages, we found server matrix degradation and increased expression of DNA methyltransferase proteins. We thus performed genome-wide DNA methylation analysis on human HA (N=5) and osteoarthritis (OA) (N=5) articular cartilages, and identified 1228 differentially methylated regions (DMRs) associated with HA. Functional enrichment analyses revealed the association between DMR genes (DMGs) and extracellular matrix (ECM) organization. Among these DMGs, Tenascin XB (TNXB) expression was down-regulated in human and mouse HA cartilages. The loss of Tnxb in F8-/- mouse cartilage provided a disease-promoting role in HA by augmenting cartilage degeneration and subchondral bone loss. Tnxb knockdown also promoted chondrocyte apoptosis and inhibited phosphorylation of AKT. Importantly, AKT agonist showed chondroprotective effects following Tnxb knockdown. Together, our findings indicate that exposure of cartilage to blood leads to alterations in DNA methylation, which is functionally related to ECM homeostasis, and further demonstrate a critical role of TNXB in HA cartilage degeneration by activating AKT signaling. These mechanistic insights allow development of potentially new strategies for HA cartilage protection.

Integrated comparison of the mRNAome in cartilage, synovium, and macrophages in osteoarthritis

The precise molecular mechanisms associated with osteoarthritis (OA), the most common musculoskeletal disorder, are poorly understood. There are currently no effective treatments to prevent the initiation and progression of the disease. In recent years, the development of mRNAome has made it possible to identify new mechanisms and therapeutic targets. However, the differentially expressed genes screened by different microarrays are not completely the same. In order to avoid this shortcoming, we integrate the different genes from different tissues and data sets, and select the commonly expressed genes for further studies.

Metabolite asymmetric dimethylarginine (ADMA) functions as a destabilization enhancer of SOX9 mediated by DDAH1 in osteoarthritis

Osteoarthritis (OA) is a degenerative disease with a series of metabolic changes accompanied by many altered enzymes. Here, we report that the down-regulated dimethylarginine dimethylaminohydrolase-1 (DDAH1) is accompanied by increased asymmetric dimethylarginine (ADMA) in degenerated chondrocytes and in OA samples. Global or chondrocyte-conditional knockout of ADMA hydrolase DDAH1 accelerated OA development in mice. ADMA induces the degeneration and senescence of chondrocytes and reduces the extracellular matrix deposition, thereby accelerating OA progression. ADMA simultaneously binds to SOX9 and its deubiquitinating enzyme USP7, blocking the deubiquitination effects of USP7 on SOX9 and therefore leads to SOX9 degradation. The ADMA level in synovial fluids of patients with OA is increased and has predictive value for OA diagnosis with good sensitivity and specificity. Therefore, activating DDAH1 to reduce ADMA level might be a potential therapeutic strategy for OA treatment.

The lncRNA PILA promotes NF-κB signaling in osteoarthritis by stimulating the activity of the protein arginine methyltransferase PRMT1

Inflammatory cytokine-induced activation of nuclear factor κB (NF-κB) signaling plays a critical role in the pathogenesis of osteoarthritis (OA). We identified PILA as a long noncoding RNA (lncRNA) that enhances NF-κB signaling and OA. The abundance of PILA was increased in damaged cartilage from patients with OA and in human articular chondrocytes stimulated with the proinflammatory cytokine tumor necrosis factor (TNF). Knockdown of PILA inhibited TNF-induced NF-κB signaling, extracellular matrix catabolism, and apoptosis in chondrocytes, whereas ectopic expression of PILA promoted NF-κB signaling and matrix degradation. PILA promoted PRMT1-mediated arginine methylation of DExH-box helicase 9 (DHX9), leading to an increase in the transcription of the gene encoding transforming growth factor β-activated kinase 1 (TAK1), an upstream activator of NF-κB signaling. Furthermore, intra-articular injection of an adenovirus vector encoding PILA triggered spontaneous cartilage loss and exacerbated posttraumatic OA in mice. This study provides insight into the regulation of NF-κB signaling in OA and identifies a potential therapeutic target for this disease.

Crosstalk Among circRNA/lncRNA, miRNA, and mRNA in Osteoarthritis

Osteoarthritis (OA) is a joint disease that is pervasive in life, and the incidence and mortality of OA are increasing, causing many adverse effects on people's life. Therefore, it is very vital to identify new biomarkers and therapeutic targets in the clinical diagnosis and treatment of OA. ncRNA is a nonprotein-coding RNA that does not translate into proteins but participates in protein translation. At the RNA level, it can perform biological functions. Many studies have found that miRNA, lncRNA, and circRNA are closely related to the course of OA and play important regulatory roles in transcription, post-transcription, and post-translation, which can be used as biological targets for the prevention, diagnosis, and treatment of OA. In this review, we summarized and described the various roles of different types of miRNA, lncRNA, and circRNA in OA, the roles of different lncRNA/circRNA-miRNA-mRNA axis in OA, and the possible prospects of these ncRNAs in clinical application.

Apolipoprotein D as a Potential Biomarker and Construction of a Transcriptional Regulatory-Immune Network Associated with Osteoarthritis by Weighted Gene Coexpression Network Analysis

OBJECTIVE

Synovial inflammation influences the progression of osteoarthritis (OA). Herein, we aimed to identify potential biomarkers and analyze transcriptional regulatory-immune mechanism of synovitis in OA using weighted gene coexpression network analysis (WGCNA).

DESIGN

A data set of OA synovium samples (GSE55235) was analyzed based on WGCNA. The most significant module with OA was identified and function annotation of the module was performed, following which the hub genes of the module were identified using Pearson correlation and a protein-protein interaction network was constructed. A transcriptional regulatory network of hub genes was constructed using the TRRUST database. The immune cell infiltration of OA samples was evaluated using the single-sample Gene Set Enrichment Analysis (ssGSEA) method. The hub genes coexpressed in multiple tissues were then screened out using data sets of synovium, cartilage, chondrocyte, subchondral bone, and synovial fluid samples. Finally, transcriptional factors and coexpressed hub genes were validated via experiments.

RESULTS

The turquoise module of GSE55235 was identified via WGCNA. Functional annotation analysis showed that "mineral absorption" and "FoxO signaling pathway" were mostly enriched in the module. JUN, EGR1, FOSB, and KLF4 acted as central nodes in protein-protein interaction network and transcription factors to connect several target genes. "Activated B cell," "activated CD4T cell," "eosinophil," "neutrophil," and "type 17 T helper cell" showed high immune infiltration, while FOSB, KLF6, and MYBL2 showed significant negative correlation with type 17 T helper cell.

CONCLUSIONS

Our results suggest that the expression level of apolipoprotein D (APOD) was correlated with OA. Furthermore, transcriptional regulatory-immune network was constructed, which may contribute to OA therapy.

The function of lncRNAs in the pathogenesis of osteoarthritis

Osteoarthritis (OA), one of the most common motor system disorders, is a degenerative disease involving progressive joint destruction caused by a variety of factors. At present, OA has become the fourth most common cause of disability in the world. However, the pathogenesis of OA is complex and has not yet been clarified. Long non-coding RNA (lncRNA) refers to a group of RNAs more than 200 nucleotides in length with limited protein-coding potential, which have a wide range of biological functions including regulating transcriptional patterns and protein activity, as well as binding to form endogenous small interference RNAs (siRNAs) and natural microRNA (miRNA) molecular sponges. In recent years, a large number of lncRNAs have been found to be differentially expressed in a variety of pathological processes of OA, including extracellular matrix (ECM) degradation, synovial inflammation, chondrocyte apoptosis, and angiogenesis. Obviously, lncRNAs play important roles in regulating gene expression, maintaining the phenotype of cartilage and synovial cells, and the stability of the intra-articular environment. This article reviews the results of the latest research into the role of lncRNAs in a variety of pathological processes of OA, in order to provide a new direction for the study of OA pathogenesis and a new target for prevention and treatment. Cite this article: Bone Joint Res 2021;10(2):122-133.

The umbilical cord mesenchymal stem cell-derived exosomal lncRNA H19 improves osteochondral activity through miR-29b-3p/FoxO3 axis

BACKGROUND

Our previous study revealed that the exosomal lncRNA H19 derived from umbilical cord mesenchymal stem cells (UMSCs) plays a pivotal role in osteochondral regeneration. In this study, we investigated whether the exosomal lncRNA H19 could act as a competing endogenous RNA (ceRNA) to potentiate osteochondral activity in chondrocytes.

METHODS

Dual-luciferase reporter assay, RNA pull-down, RNA immunoprecipitation (RIP), and fluorescence in situ hybridization (FISH) were carried to verify the interaction between miR-29b-3p and both lncRNA H19 and the target mRNA FoxO3. Chondrocytes were treated with UMSC-derived exosomes, which highly expressing lncRNA H19 expression, followed by apoptosis, migration, senescence, and matrix secretion assessments. An in vivo SD rat cartilage defect model was carried out to explore the role and mechanism of lncRNA H19/miR-29b-3p.

RESULTS

UMSCs were successfully identified, and exosomes were successfully extracted. Exosomes exhibited the ability to transfer lncRNA H19 to chondrocytes. Mechanistically, exosomal lncRNA H19 potentiated osteochondral activity by acting as a competing endogenous sponge of miR-29b-3p, and miR-29b-3p directly targeted FoxO3. Intra-articular injection of exosomes overexpressing lncRNA H19 could promote sustained cartilage repair; however, this effect could be undermined by miR-29b-3p agomir.

CONCLUSIONS

Our study revealed a significant role in the development of strategies against cartilage defects for UMSC-derived exosomes that overexpress lncRNA H19. Exosomal H19 was found to promote chondrocyte migration, matrix secretion, apoptosis suppression, as well as senescence suppression, both in vitro and in vivo. The specific mechanism lies in the fact that exosomal H19 acts as a ceRNA against miR-29b-3p to upregulate FoxO3 in chondrocytes.

A landscape of circulating long non-coding RNA (lncRNA) expression profile and the predictive value of candidate lncRNAs for disease risk of knee osteoarthritis

Background

This study aimed to investigate the plasma long non‐coding RNA (lncRNA) expression profile in knee osteoarthritis (KOA) patients and the value of candidate lncRNAs for predicting KOA risk.

Methods

Plasma was obtained for RNA sequencing (RNA‐seq) in eight KOA patients and eight healthy controls (Ctrls). Ten candidate lncRNAs were then selected from the differentially expressed (DE) lncRNAs according to the rank of absolute value of Log₂ (fold change). Afterward, RT‐qPCR was used to examine 10 candidate lncRNAs expressions in plasma of 100 KOA patients and 100 Ctrls.

Results

In eight KOA patients and eight Ctrls, principal component analysis and heatmap plots disclosed that lncRNA and mRNA expression profile could distinguish KOA patients from Ctrls. Then Volcano plot identified 418 upregulated lncRNAs, 347 downregulated lncRNAs, 521 upregulated mRNAs, and 333 downregulated mRNAs in KOA patients compared to Ctrls. Next, enrichment analyses revealed that DE lncRNAs were mainly enriched in biological processes, molecular functions, and signaling pathways related to inflammation and bone formation. In 100 KOA patients and 100 Ctrls, eight candidate lncRNAs were dysregulated in KOA patients compared to Ctrls, including lncRNA ABCF2P2, lncRNA RP13‐16H11.7, lncRNA CTC‐340A15.2, lncRNA RP4‐735C1.6, lncRNA RP11‐293G6‐B.8, lncRNA RP11‐1246C19.1, lncRNA RP11‐303E16.6, and lncRNA RP5‐882C2.2. Receiver operating characteristic curve analysis revealed that these eight candidate lncRNAs presented with values for predicting KOA risk. Furthermore, multivariate logistic regression elucidated that six candidate lncRNAs could independently predict KOA risk.

Conclusion

We disclosed a landscape of circulating lncRNA expression profile in KOA patients, and discovered several specific lncRNAs which could assist in KOA management.

Study of Osteoarthritis-Related Hub Genes Based on Bioinformatics Analysis

Osteoarthritis (OA) is a common cause of morbidity and disability worldwide. However, the pathogenesis of OA is unclear. Therefore, this study was conducted to characterize the pathogenesis and implicated genes of OA. The gene expression profiles of GSE82107 and GSE55235 were downloaded from the Gene Expression Omnibus database. Altogether, 173 differentially expressed genes including 68 upregulated genes and 105 downregulated genes in patients with OA were selected based on the criteria of ∣log fold-change | >1 and an adjusted p value < 0.05. Protein-protein interaction network analysis showed that FN1, COL1A1, IGF1, SPP1, TIMP1, BGN, COL5A1, MMP13, CLU, and SDC1 are the top ten genes most closely related to OA. Quantitative reverse transcription-polymerase chain reaction showed that the expression levels of COL1A1, COL5A1, TIMP1, MMP13, and SDC1 were significantly increased in OA. This study provides clues for the molecular mechanism and specific biomarkers of OA.

Identification of lncRNA and mRNA Biomarkers in Osteoarthritic Degenerative Meniscus by Weighted Gene Coexpression Network and Competing Endogenous RNA Network Analysis

BACKGROUND

Long noncoding RNAs (lncRNAs) play a crucial role in varieties of biological processes. This study is aimed at investigating meniscal degeneration-specific lncRNAs and mRNAs and their related networks in knee osteoarthritis (KOA).

METHODS

The dataset GSE98918, which included 24 meniscus samples and related clinical data, was downloaded from the Gene Expression Omnibus database. The differentially expressed lncRNAs and mRNAs in the meniscus between KOA and control groups were identified. Based on the enriched differentially expressed lncRNAs and mRNAs, we constructed the coexpression network using WGCNA (weighted correlation network analysis) and identified the critical module related to KOA. For mRNAs in the key module, gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were carried out using the DAVID database. A competing endogenous RNA network (ceRNA) based on the screened mRNAs, lncRNAs, and related miRNAs was constructed to reveal presumptive biomarkers further. Finally, the hub lncRNAs and mRNAs were screened, and the diagnostic value was evaluated using a receiver operating characteristic (ROC) curve. Hub mRNAs were validated using the dataset GSE113825.

RESULTS

We screened 208 significantly differentially expressed lncRNAs and mRNAs in menisci between the KOA and non-KOA samples, which were enriched in sixteen modules using WGCNA, especially the green module. Coexpression network based on the enriched differentially expressed lncRNAs and mRNAs in the green module uncovered 5 lncRNAs and 56 mRNAs. The lncRNA-miRNA-mRNA ceRNA network revealed that lnc-HLA-DQA1-5, lnc-RP11-127H5.1.1-1, lnc-RTN2-1, IGFBP4 (insulin-like growth factor binding protein 4), and KLF2 (Kruppel-like factor 2) were significantly correlated with the meniscus degeneration of KOA. ROC curve analysis revealed that these hub lncRNAs and mRNAs showed excellent diagnostic value for KOA.

CONCLUSIONS

These hub lncRNAs and mRNAs were potential prognostic biomarkers for the meniscus degeneration of KOA. Further studies are required to validate these new biomarkers and better understand the pathological process of the meniscus degeneration of KOA.

Differential Expression of Long Noncoding RNAs and Their Function-Related mRNAs in the Peripheral Blood of Allergic Rhinitis Patients

BACKGROUND

The mechanism of long noncoding RNAs (lncRNAs) involved in the development of allergic rhinitis (AR) remains unclear.

OBJECTIVE

We investigated the mechanism by which differentially expressed lncRNAs contribute to pathogenesis of AR.

METHODS

Expression profiles of lncRNAs and mRNAs were analyzed by microarray detection from the blood samples of 3 AR patients and 3 control subjects, and the main lncRNAs were verified by quantitative real-time polymerase chain reaction (qRT-PCR) in the peripheral blood of 16 AR patients and 18 control subjects. GO (Gene_Ontology), Pathway, and Disease analysis of differentially expressed lncRNAs and mRNAs, and transcription factor prediction analysis were performed to explore synergistic effect of differentially expressed lncRNAs and their function-related mRNAs on AR pathogenesis.

RESULTS

Thirty-one lncRNAs were differentially expressed in the peripheral blood from AR patients, and 4 of the 5 most differentially expressed lncRNAs had significantly higher levels in AR patients than in control subjects by qRT-PCR analysis. A lncRNA-mRNA coexpression network analysis identified 16 pairs of positive correlations between the 4 lncRNAs and coexpressed mRNAs. GO, Pathway, and Disease analyses indicated that the 4 lncRNAs were correlated with 7 mRNAs enriched in terms of inflammation, immune response, and allergic diseases. Transcription factor prediction results suggested that Oct-1, AP-1, NF-kappaB, and c-Rel play key roles in the pathogenesis of AR mediated by lncRNAs.

CONCLUSION

Our results provide new insights into how lncRNAs and their function-related mRNAs might contribute to AR.

LINC00623/miR-101/HRAS axis modulates IL-1β-mediated ECM degradation, apoptosis and senescence of osteoarthritis chondrocytes

Chondrocyte apoptosis and extracellular matrix (ECM) degeneration have been implicated in the pathogenesis of osteoarthritis (OA). Based on previously reported microarray analysis, HRAS (Harvey rat sarcoma viral oncogene homolog), a member of the RAS protein family, was chosen as a potential regulator of OA chondrocyte apoptosis and ECM degradation. HRAS expression was downregulated in OA tissues, particularly in mild-OA tissues. HRAS overexpression partially attenuated IL-1β-induced OA chondrocyte apoptosis and ECM degradation. Similar to HRAS, the long non-coding RNA LINC00623 was downregulated in OA tissues. LINC00623 knockdown enhanced IL-1β-induced OA chondrocyte apoptosis and ECM degradation, which could be partially reversed by HRAS overexpression. It has been reported that lncRNAs act as ceRNAs of miRNAs to exert their function. Herein, miR-101 was predicted to bind to both LINC00623 and HRAS, which was further confirmed by luciferase reporter and RIP assays. LINC00623 competed with HRAS for miR-101 binding, therefore reducing the inhibitory effect of miR-101 on HRAS expression. More importantly, the effect of LINC00623 was partially eliminated by miR-101 inhibition. Overall, the LINC00623/miR-101/HRAS axis modulates OA chondrocyte apoptosis, senescence and ECM degradation through MAPK signaling, which might play a critical role in OA development.