LncRNA FOXD2-AS1 regulates chondrocyte proliferation in osteoarthritis by acting as a sponge of miR-206 to modulate CCND1 expression

M6A Modification and Transcription Analysis of LncRNA in Cerebral Ischemia/Reperfusion Injury

LncRNA is a major factor in the occurrence and development of many diseases. However, its mechanism in cerebral ischemia/reperfusion injury (CIRI) is yet unknown. In this study, the transcriptional level and methylation modification level of LncRNAs before and after mechanical thrombectomy were compared by high-throughput sequencing. Venn diagram, Spearman correlation analysis, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, TargetScan, and miRanda were used to analyze the experimental data. The results showed that four key LncRNAs changed at both transcription and methylation levels. Specifically, LncRNA FAR2, LINC02431, and AL357060.1 were downregulated and hypomethylated, while LncRNA FOXD2-AS1 was upregulated and hypomethylated. Moreover, positive regulation of angiogenesis, protein domain-specific binding, autophagy pathway, PPAR signaling pathway, and MAPK signaling pathway were co-enriched between LncRNAs with different expression levels and different methylation levels. Finally, a LncRNA-miRNA-mRNA network was constructed. Therefore, this study explored the potential key LncRNAs and regulatory mechanisms of CIRI.

Unraveling the molecular landscape of osteoarthritis: A comprehensive review focused on the role of non-coding RNAs

Osteoarthritis (OA) poses a significant global health challenge, with its prevalence anticipated to increase in the coming years. This review delves into the emerging molecular biomarkers in OA pathology, focusing on the roles of various molecules such as metabolites, noncoding RNAs (ncRNAs), including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Advances in omics technologies have transformed biomarker identification, enabling comprehensive analyses of the complex pathways involved in OA pathogenesis. Notably, ncRNAs, especially miRNAs and lncRNAs, exhibit dysregulated expression patterns in OA, presenting promising opportunities for diagnosis and therapy. Additionally, the intricate interplay between epigenetic modifications and OA progression highlights the regulatory role of epigenetics in gene expression dynamics. Genome-wide association studies have pinpointed key genes undergoing epigenetic changes, providing insights into the inflammatory processes and chondrocyte hypertrophy typical of OA. Understanding the molecular landscape of OA, including biomarkers and epigenetic mechanisms, holds significant potential for developing innovative diagnostic tools and therapeutic strategies for OA management.

Deletion of Pax1 scoliosis-associated regulatory elements leads to a female-biased tail abnormality

Adolescent idiopathic scoliosis (AIS), a sideways curvature of the spine, is sexually dimorphic, with increased incidence in females. A genome-wide association study identified a female-specific AIS susceptibility locus near the PAX1 gene. Here, we use mouse enhancer assays, three mouse enhancer knockouts, and subsequent phenotypic analyses to characterize this region. Using mouse enhancer assays, we characterize a sequence, PEC7, which overlaps the AIS-associated variant, and find it to be active in the tail tip and intervertebral disc. Removal of PEC7 or Xe1, a known sclerotome enhancer nearby, or deletion of both sequences lead to a kinky tail phenotype only in the Xe1 and combined (Xe1+PEC7) knockouts, with only the latter showing a female sex dimorphic phenotype. Extensive phenotypic characterization of these mouse lines implicates several differentially expressed genes and estrogen signaling in the sex dimorphic bias. In summary, our work functionally characterizes an AIS-associated locus and dissects the mechanism for its sexual dimorphism.

A review on the role of FOXD2-AS1 in human disorders

FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1) is a long non-coding RNA being transcribed from a locus on chromosome 1p33. This transcript has been found to be up-regulated in tumor samples of almost all types of malignancies in association with a significant increase in malignant features. FOXD2-AS1 can affect activity of PI3K/AKT, AKT/mTOR, Hippo/YAP, Notch, NRf2, Wnt/β-catenin, NF-ƙB and ERK/MAPK pathways. Furthermore, it can enhance stem cell properties in cancer cells and prompt epithelial-mesenchymal transition. It is also involved in induction of resistance to a variety of anticancer agents such as adriamycin, cisplatin, 5-fluorouracil, temozolomide and gemcitabine. This article summarizes the impact of FOXD2-AS1 in diverse human disorders.

Highly-expressed lncRNA FOXD2-AS1 in adipose mesenchymal stem cell derived exosomes affects HaCaT cells via regulating miR-185-5p/ROCK2 axis

The healing of skin wounds is a highly coordinated multi-step process that occurs after trauma including surgical incisions, thermal burns, and chronic ulcers. In this study, the authors investigated lncRNA FOXD2-AS1 function in adipose mesenchymal exosomes from ADMSCs that were successfully extracted. Highly expressed lncRNA FOXD2-AS1 in ADMSCs-exosomes accelerated HaCaT cell migration and proliferation. LncRNA FOXD2-AS1 negatively targeted miR-185-5p, and miR-185-5p negatively targeted ROCK2. Highly expressed lncRNA FOXD2-AS1 in ADMSCs-exosomes promoted HaCaT cell migration and proliferation via down-regulating miR-185-5p and further up-regulating ROCK2. In conclusion, LncRNA FOXD2-AS1 overexpression in ADMSCs derived exosomes might accelerate HaCaT cell migration and proliferation via modulating the miR-185-5p/ROCK2 axis.

Inhibition of LncRNA SNHG14 protects chondrocyte from injury in osteoarthritis via sponging miR-137

Long-chain noncoding small nucleolar RNA host gene 14 (LncRNA SNHG14) is highly expressed in various diseases and promotes diseases progression, but the role and mechanism of LncRNA SNHG14 on targeting miR-137 in promoting osteoarthritis (OA) chondrocyte injury remains unclear. To measure the expression of the LncRNAs SNHG14 and miR-137, cell survival, inflammatory response, chondrocyte apoptosis, and extracellular matrix (ECM) levels, we subjected human chondrocytes to a variety of lipopolysaccharide (LPS) concentrations. To measure the luciferase activity of SNHG14-WT and SNHG14-MUT transfected with miR-137 mimic or miR-NC mimic, luciferase reporter genes were utilized. The results showed that chondrocyte viability was significantly inhibited with LPS treatment and chondrocyte inflammatory response, apoptosis and extracellular matrix degradation were significantly increased. However, the above results were significantly reversed after LncRNA SNHG14 inhibition. The luciferase activity bound to miR-137 was decreased in SNHG14-WT group, but there was no change in SNHG14-mut group, which indicated that LncRNA SNHG14 inhibited miR-137 expression as a miRNA sponge. In conclusion, inhibition of LncRNA SNHG14 attenuates chondrocyte inflammatory response, apoptosis and extracellular matrix degradation by targeting miR-137 in LPS induced chondrocytes.

The emerging role of lncRNAs in osteoarthritis development and potential therapy

Osteoarthritis impairs the functions of various joints, such as knees, hips, hands and spine, which causes pain, swelling, stiffness and reduced mobility in joints. Multiple factors, including age, joint injuries, obesity, and mechanical stress, could contribute to osteoarthritis development and progression. Evidence has demonstrated that genetics and epigenetics play a critical role in osteoarthritis initiation and progression. Noncoding RNAs (ncRNAs) have been revealed to participate in osteoarthritis development. In this review, we describe the pivotal functions and molecular mechanisms of numerous lncRNAs in osteoarthritis progression. We mention that long noncoding RNAs (lncRNAs) could be biomarkers for osteoarthritis diagnosis, prognosis and therapeutic targets. Moreover, we highlight the several compounds that alleviate osteoarthritis progression in part via targeting lncRNAs. Furthermore, we provide the future perspectives regarding the potential application of lncRNAs in diagnosis, treatment and prognosis of osteoarthritis.

miR-5581 Contributes to Osteoarthritis by Targeting NRF1 to Disturb the Proliferation and Functions of Chondrocytes

Chondrocyte survival is critical for the preservation of a healthy cartilage matrix. Limited chondrocyte function and survival can result in articular cartilage failure, thereby contributing to osteoarthritis (OA). In this study, miR-5581 was significantly up-regulated in OA samples, and miR-5581-associated genes were enriched in Kras signaling. miR-5581 up-regulation was observed in clinical OA samples and IL-1β-stimulated chondrocytes. miR-5581 inhibition attenuated IL-1β-induced chondrocyte proliferation suppression, extracellular matrix (ECM) synthesis suppression and degradation, and IL-1β-suppressed Kras signaling activation. miR-5581 was targeted to inhibit NRF1. In IL-1β-treated chondrocytes, NRF1 overexpression attenuated IL-1β-induced cellular damage and partially abolished the effects of miR-5581 overexpression on IL-1β-stimulated chondrocytes. NRF1 was down-regulated in knee joint cartilage of OA mice. In conclusion, miR-5581, which was up-regulated in OA samples and IL-1β-stimulated chondrocytes, inhibited chondrocyte proliferation and ECM synthesis, and promoted ECM degradation through targeting NRF1, whereby Kras signaling might be involved.

The regulatory role and mechanism of lncTUG1 on cartilage apoptosis and inflammation in osteoarthritis

BACKGROUND

Long-stranded non-coding RNA TUG1 is lowly expressed in osteoarthritic chondrocytes. This study aimed to elucidate the role of TUG1 in osteoarthritic cartilage damage and the underlying mechanisms.

METHODS

Combined database analysis, using primary chondrocytes as well as the C28/I2 cell line, was performed by qRT-PCR, Western blotting, and immunofluorescence to determine the expression of TUG1, miR-144-3p, DUSP1, and other target proteins. Dual luciferase reporter gene and RIP to verify direct interaction of TUG1 with miR-144-3-p and miR-144-3-p with DUSP1, Annexin V-FITC/PI double staining to detect apoptosis. CCK-8 to detect cell proliferation. The biological significance of TUG1, miR-144-3p, and DUSP1 was assessed in vitro experiments using siRNA for TUG1, mimic and repressor for miR-144-3p, and overexpression plasmid for DUSP1. In this study, all data were subjected to a t-test or one-way analysis of variance with a p-value < 0.05 as the cutoff.

RESULTS

TUG1 expression was closely associated with osteoarthritic chondrocyte damage, and knockdown of TUG1 significantly promoted chondrocyte apoptosis and inflammation. In the present study, we found that TUG1 inhibited chondrocyte apoptosis and inflammation by competitively binding miR-144-3p, deregulating the negative regulatory effect of miR-144-3p on DUSP1, promoting DUSP1 expression, and inhibiting the p38 MAPK signaling pathway.

CONCLUSIONS

In conclusion, our study clarifies the role of the ceRNA regulatory network of TUG1/miR-144-3p/DUSP1/P38 MAPK in OA cartilage injury and provides an experimental and theoretical basis for genetic engineering tools to promote articular cartilage repair.

Pro-inflammatory activity of long noncoding RNA FOXD2-AS1 in Achilles tendinopathy

Achilles tendinopathy is a prevalent clinical problem that plagues athletes and general populations. Achilles tendon healing is a complex process, and so far, there is no successful long-term solution to Achilles tendinopathy in the field of microsurgery due to its poor natural regeneration ability. Limitations in understanding the pathogenesis of Achilles tendon development and Achilles tendon injury hinder clinical treatment developments. There is an increasing demand for innovative conservative treatments that can improve Achilles tendon injury. In this study, a Sprague-Dawley rat model of Achilles tendinopathy was established. Lentiviral vectors that interfere with the expression of FOXD2-AS1, miR-21-3p, or PTEN were injected every 3 days. Rats were euthanized after 3 weeks, and the effect of FOXD2-AS1, miR-21-3p, or PTEN on Achilles tendon healing was analyzed by histological observation, biomechanical test, and examinations of inflammatory factors and tendon markers. As measured, downregulating FOXD2-AS1 or upregulating miR-21-3p improved histological structure, suppressed inflammation, promoted the expression of tendon markers, and optimized the biomechanical properties of Achilles tendon. Upregulating PTEN was capable of reversing the promoting effect of inhibition of FOXD2-AS1 on Achilles tendon healing. As concluded, deficiency of FOXD2-AS1 accelerates the healing of Achilles tendon injury and improves tendon degeneration by regulating the miR-21-3p/PTEN axis and promoting the activation of the PI3K/AKT signaling pathway.

Deletion of Pax1 scoliosis-associated regulatory elements leads to a female-biased tail abnormality

Adolescent idiopathic scoliosis (AIS), a sideways curvature of the spine, is sexually dimorphic, with increased incidence in females. A GWAS identified a female-specific AIS susceptibility locus near the PAX1 gene. Here, we used mouse enhancer assays, three mouse enhancer knockouts and subsequent phenotypic analyses to characterize this region. Using mouse enhancer assays, we characterized a sequence, PEC7, that overlaps the AIS-associated variant, and found it to be active in the tail tip and intervertebral disc. Removal of PEC7 or Xe1, a known sclerotome enhancer nearby, and deletion of both sequences led to a kinky phenotype only in the Xe1 and combined (Xe1+PEC7) knockouts, with only the latter showing a female sex dimorphic phenotype. Extensive phenotypic characterization of these mouse lines implicated several differentially expressed genes and estrogen signaling in the sex dimorphic bias. In summary, our work functionally characterizes an AIS-associated locus and dissects the mechanism for its sexual dimorphism.

Emerging role of lncRNAs in osteoarthritis: An updated review

Osteoarthritis (OA) is a prevalent joint disease, which is associated with progressive articular cartilage loss, synovial inflammation, subchondral sclerosis and meniscus injury. The molecular mechanism underlying OA pathogenesis is multifactorial. Long non-coding RNAs (lncRNAs) are non-protein coding RNAs with length more than 200 nucleotides. They have various functions such as modulating transcription and protein activity, as well as forming endogenous small interfering RNAs (siRNAs) and microRNA (miRNA) sponges. Emerging evidence suggests that lncRNAs might be involved in the pathogenesis of OA which opens up a new avenue for the development of new biomarkers and therapeutic strategies. The purpose of this review is to summarize the current clinical and basic experiments related to lncRNAs and OA with a focus on the extensively studied H19, GAS5, MALAT1, XIST and HOTAIR. The potential translational value of these lncRNAs as therapeutic targets for OA is also discussed.

Multi-omics molecular biomarkers and database of osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis in the adult population and is a leading cause of disability. OA-related genetic loci may play an important role in clinical diagnosis and disease progression. With the rapid development of diverse technologies and omics methods, many OA-related public data sets have been accumulated. Here, we retrieved a diverse set of omics experimental results from 159 publications, including genome-wide association study, differentially expressed genes and differential methylation regions, and 2405 classified OA-related gene markers. Meanwhile, based on recent single-cell RNA-seq data from different joints, 5459 cell-type gene markers of joints were collected. The information has been integrated into an online database named OAomics and molecular biomarkers (OAOB). The database (http://ibi.zju.edu.cn/oaobdb/) provides a web server for OA marker genes, omics features and so on. To our knowledge, this is the first database of molecular biomarkers for OA.

LncRNAs in Osteoarthritis

Osteoarthritis (OA) is a progressive joint disease that affects millions of older adults around the world. With increasing rates of incidence and prevalence worldwide, OA has become an enormous global socioeconomic burden on healthcare systems. Long non-coding ribonucleic acids (lncRNAs), essential functional molecules in many biological processes, are a group of non-coding RNAs that are greater than approximately 200 nucleotides in length. Fast-growing and recent developments in lncRNA research are captivating and represent a novel and promising field in understanding the complexity of OA pathogenesis. The involvement of lncRNAs in OA's pathological processes and their altered expressions in joint tissues, blood and synovial fluid make them attractive candidates for the diagnosis and treatment of OA. We focus on the recent advances in major regulator mechanisms of lncRNAs in the pathophysiology of OA and discuss potential diagnostic and therapeutic uses of lncRNAs for OA. We investigate how upregulation or downregulation of lncRNAs influences the pathogenesis of OA and how we can use lncRNAs to elucidate the molecular mechanism of OA. Furthermore, we evaluate how we can use lncRNAs as a diagnostic marker or therapeutic target for OA. Our study not only provides a comprehensive review of lncRNAs regarding OA's pathogenesis but also contributes to the elucidation of its molecular mechanisms and to the development of diagnostic and therapeutic approaches for OA.

The Role of Mitochondrial Metabolism, AMPK-SIRT Mediated Pathway, LncRNA and MicroRNA in Osteoarthritis

Osteoarthritis (OA) is the most common joint disease characterized by degeneration of articular cartilage and causes severe joint pain, physical disability, and impaired quality of life. Recently, it was found that mitochondria not only act as a powerhouse of cells that provide energy for cellular metabolism, but are also involved in crucial pathways responsible for maintaining chondrocyte physiology. Therefore, a growing amount of evidence emphasizes that impairment of mitochondrial function is associated with OA pathogenesis; however, the exact mechanism is not well known. Moreover, the AMP-activated protein kinase (AMPK)–Sirtuin (SIRT) signaling pathway, long non-coding RNA (lncRNA), and microRNA (miRNA) are important for regulating the physiological and pathological processes of chondrocytes, indicating that these may be targets for OA treatment. In this review, we first focus on the importance of mitochondria metabolic dysregulation related to OA. Then, we show recent evidence on the AMPK-SIRT mediated pathway associated with OA pathogenesis and potential treatment options. Finally, we discuss current research into the effects of lncRNA and miRNA on OA progression or inhibition.

LINC00941 promoted in vitro progression and glycolysis of laryngocarcinoma by upregulating PKM via activating the PI3K/AKT/mTOR signaling pathway

Background

LINC00941 has been proved to be related to various tumors, but its relationship with laryngocarcinoma remains vague.

Methods

LINC00941 expression in laryngocarcinoma tumor and laryngocarcinoma cells was determined by real time‐quantitative polymerase chain reaction (RT‐qPCR). Besides, the five‐year survival of laryngocarcinoma patients with different LINC00941 expression was analyzed with Kaplan–Meier survival analysis, and the clinical characteristics of laryngocarcinoma patients were also recorded. After transfection, cell viability, cell proliferation, apoptosis, cell cycle, migration, and invasion were detected by cell counting kit‐8 (CCK‐8), colony formation, flow cytometry, cell scratch, and Transwell assays, respectively. Glycolysis was assessed by the colorimetric method. Expressions of proliferation‐associated proteins, migration‐associated proteins, glycolysis‐associated proteins, and phosphatidylinositol 3‐kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signal pathway‐associated proteins were detected by Western blot.

Results

In laryngocarcinoma tumor tissues and cells, LINC00941 was highly expressed. High expression of LINC00941 decreased the 5‐year survival of laryngocarcinoma patients, and it was positively related to lymph node metastasis and clinical stages. LINC00941 overexpression decreased apoptosis but promoted cell viability, proliferation, cell‐cycle progression, migration, and invasion, and glucose consumption and lactate production in laryngocarcinoma cells. Moreover, LINC00941 overexpression elevated expressions of Ki‐67, PCNA, MMP2, N‐Cadherin, HK2, PFKFB4, and PKM, activated the PI3K/AKT/mTOR signal pathway but reduced E‐Cadherin expression, while LINC00941 silencing had the opposite effects. PKM overexpression reversed the effects of LINC00941 silencing on cellular and glycolytic phenotypes.

Conclusion

LINC00941 promoted in vitro progression and glycolysis of laryngocarcinoma cells by upregulating PKM via activating the PI3K/AKT/mTOR signaling pathway.

Knockdown of long noncoding RNA HUMT inhibits the proliferation and metastasis by regulating miR-455-5p/LRP4 axis in hepatocellular carcinoma

The present study aimed at investigating the effects and mechanism of long noncoding RNA highly upregulated in metastatic triple-negative breast cancer lymph node (lncRNA HUMT) in hepatocellular carcinoma (HCC). Quantitative real-time polymerase chain reaction was used to assess the expression of HUMT, microRNA (miR)-455-5p, and low-density lipoprotein receptor-related protein 4 (LRP4) in HCC tissues. Colony forming and 5-ethynyl-2′-deoxyuridine assays were performed to assess cell proliferation. Transwell assay was performed to measure cell migration and invasion. Cell cycle distribution was assessed using flow cytometry. The protein expression of LRP4, proliferating cell nuclear antigen (PCNA), matrix metallopeptidase 2 (MMP-2), and MMP-9 was detected using western blot. Luciferase reporter assay and RNA immunoprecipitation assay was used to confirm the target association between miR-455-5p and HUMT or LRP4. In our study, the level of HUMT was enhanced in HCC tissues and cells. Cell proliferation, invasion, and migration in HCC cells were repressed by knockdown of HUMT, and knockdown of HUMT arrested cells in G1 phase and decreased the levels of PCNA, MMP-2, and MMP-9. MiR-455-5p was a target of HUMT. Lowexpression of miR-455-5p reversed the inhibitive influence on HCC cells induced by of HUMT silencing. LRP4 was a target of miR-455-5p and was negatively regulated by miR-455-5p. In addition, LRP4 expression was positively modified by HUMT, and LRP4 inhibited the inhibitory effects on HCC cells induced by HUMT silencing. In conclusion, HCC cell proliferation, invasion, and migration were restrained by knockdown of HUMT, which was related to the miR-455-5p/LRP4 axis.

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.

Whole Transcriptome Mapping Identifies an Immune- and Metabolism-Related Non-coding RNA Landscape Remodeled by Mechanical Stress in IL-1β-Induced Rat OA-like Chondrocytes

Background: Osteoarthritis (OA) is a common degenerative joint disease. The aims of this study are to explore the effects of mechanical stress on whole transcriptome landscape and to identify a non-coding transcriptome signature of mechanical stress.

Methods: Next-generation RNA sequencing (RNA-seq) was performed on IL-1β-induced OA-like chondrocytes stimulated by mechanical stress. Integrated bioinformatics analysis was performed and further verified by experimental validations.

Results: A total of 5,022 differentially expressed mRNAs (DEMs), 88 differentially expressed miRNAs (DEMIs), 1,259 differentially expressed lncRNAs (DELs), and 393 differentially expressed circRNAs (DECs) were identified as the transcriptome response to mechanical stress. The functional annotation of the DEMs revealed the effects of mechanical stress on chondrocyte biology, ranging from cell fate, metabolism, and motility to endocrine, immune response, and signaling transduction. Among the DELs, ∼92.6% were identified as the novel lncRNAs. According to the co-expressing DEMs potentially regulated by the responsive DELs, we found that these DELs were involved in the modification of immune and metabolism. Moreover, immune- and metabolism-relevant DELs exhibited a notable involvement in the competing endogenous RNA (ceRNA) regulation networks. Silencing lncRNA TCONS_00029778 attenuated cellular senescence induced by mechanical stress. Moreover, the expression of Cd80 was elevated by mechanical stress, which was rescued by silencing TCONS_00029778.

Conclusion: The transcriptome landscape of IL-1β-induced OA-like chondrocytes was remarkably remodeled by mechanical stress. This study identified an immune- and metabolism-related ncRNA transcriptome signature responsive to mechanical stress and provides an insight of ncRNAs into chondrocyte biology and OA.

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.

Comprehensive expression profiles of mRNAs, lncRNAs and miRNAs in Kashin-Beck disease identified by RNA-sequencing

Kashin-Beck disease (KBD) is a chronic, endemic and deforming osteochondropathy, whose basic pathological alterations include apoptosis and necrosis of chondrocytes in articular cartilage and growth plates and imbalanced extracellular matrix metabolism. Numerous studies have reported that long noncoding RNAs (lncRNAs) and microRNA (miRNAs) are aberrantly expressed in KBD. Our study was comprised of 5 KBD patients and 5 healthy individuals and we compared the expression profiles of mRNAs, lncRNAs and miRNAs through RNA-sequencing (RNA-seq). Bioinformatic analysis of GO and KEGG was employed to conduct functional annotation and pathway enriched analysis. In total, 3194 mRNAs, 4103 lncRNAs and 1550 miRNAs were detected to be differentially expressed by RNA-seq (P < 0.05; |log₂FC| ≥1). The lysosome pathway, Wnt signaling pathway, TNF signaling pathway, endocytosis and mTOR signaling pathway were identified to be involved in the KBD development according to the result of the KEGG analysis. In addition, a ceRNA network based on lncRNA-miRNA-mRNA was constructed to probe the intricate regulatory mechanism and interaction between transcripts, which was visualized using the Cytoscape software. The ce-lncRNAs of four aberrantly expressed genes, FOSB, EGR3, BCAM and SOX6, were determined through the network. Among the identified DElncRNAs, we selected 8 differentially expressed lncRNAs to confirm the reliability of RNA-seq data by qRT-PCR in 11 KBD patients and 11 healthy individuals. We aimed to provide a comprehensive understanding ofmRNA, lncRNA and miRNA alterations between KBD patients and healthy individuals, and meanwhile reveal several potential causative molecular and signaling pathways involved in KBD.

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.

Downregulation of LncRNA OIP5-AS1 Induced by IL-1β Aggravates Osteoarthritis via Regulating miR-29b-3p/PGRN

BACKGROUND

Long noncoding RNA (lncRNA) OIP5 antisense RNA 1 (OIP5-AS1) is an oncogenic lncRNA; however, its role in osteoarthritis (OA) pathology still remains unknown.

MATERIALS AND METHODS

qRT-PCR was performed to measure the expressions of OIP5-AS1, miR-29b-3p and progranulin (PGRN) mRNA in OA cartilage tissues and normal cartilage tissues. Chondrocyte cell lines, CHON-001 and ATDC5, were treated with different doses of interleukin-1β (IL-1β) to induce the inflammatory response. Overexpression plasmids, microRNA mimics, microRNA inhibitors and small interfering RNAs were constructed and transfected into CHON-001 and ATDC5 cells. CCK-8 assay was used for determining the cell viability and Transwell assay was used for monitoring cell migration. Western blot was applied to measure the expressions of apoptosis-related proteins. Enzyme-linked immunosorbent assay (ELISA) was adopted to measure the contents of inflammatory factors. StarBase and TargetScan were used to predict the binding sites between OIP5-AS1 and miR-29b-3p, miR-29b-3p and 3'-UTR of PGRN respectively, which were verified by dual luciferase reporter assay.

RESULTS

OIP5-AS1 and PGRN mRNA were downregulated while miR-29b-3p was upregulated in OA tissues and models. The up-regulated OIP5-AS1 facilitated the proliferation and migration of CHON-001 and ATDC5 cells, while ameliorated the apoptosis and inflammatory response. However, miR-29b-3p had opposite effects. PGRN was identified as a target gene of miR-29b-3p, which could be indirectly suppressed by OIP5-AS1 knockdown.

CONCLUSION

Downregulation of OIP5-AS1 induced by IL-1β could inhibit the proliferation and migration abilities of CHON-001 and ATDC5 cells and facilitate the apoptosis and inflammation response via regulating miR-29b-3p/PGRN axis.

Bioinformatics-Based Research on Key Genes and Pathways of Intervertebral Disc Degeneration

OBJECTIVE

To find out the pathways and key genes and to reveal disc degeneration pathogenesis based on bioinformatic analyses.

DESIGN

The GSE70362 dataset was downloaded from the GEO (Gene Expression Omnibus) database. Differentially expressed genes (DEGs) between the patients having disc degeneration and healthy controls were screened by Limma package in R language. Critical genes were identified by adopting gene ontologies (GOs), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and protein-protein interaction (PPI) networks.

RESULTS

We identified 112 DEGs, including 60 genes which were upregulated and 52 that were downregulated. Analyses, such as GO and KEGG demonstrated that the DEGs got enriched in 4 biological processes and 2 signaling pathways, mainly related to disc degeneration. The PPI network analyses identified 5 key proteins, CCND1 (cyclin D1), GATA3, TNFSF11, LEF1, and DKK1 (Dickkopf related protein 1).

CONCLUSION

In this study, the DEGs and pathways determined promoted us understand the disc degeneration mechanisms. Also, the study may contribute novel biomarkers for the diagnosis and prevention of disc degeneration, and seek new treatment methods to repair and even regenerate degenerative intervertebral disc.

Integrative Analysis of the Expression of microRNA, Long Noncoding RNA, and mRNA in Osteoarthritis and Construction of a Competing Endogenous Network

This study aimed to identify potential core microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and mRNAs in osteoarthritis (OA) to construct a competing endogenous RNA (ceRNA) and co-expression network. Differentially expressed miRNAs (DEMis) in the dataset GSE143514 comprising five OA and three normal tissues were identified using the DEseq package. Core miRNAs were identified as DEMis overlapping with those reported by the human microRNA disease database. LncRNAs were predicted by the miRNA-lncRNA interactions network from the encyclopedia of RNA interactomes (ENCORI). MiRNet and ENCORI were employed to predict the mRNAs which overlapped with the differentially expressed mRNAs from the dataset GSE114007 to obtain overlapping mRNAs. MiRNA-lncRNA and miRNA-mRNA interactions were integrated to construct the ceRNA network. A total of 143 DEMis were identified in OA and normal tissues, from which hsa-miR-451a, hsa-miR-370-5p, hsa-miR-34a-5p, hsa-miR-210-3p, and hsa-miR-101-3p were assessed as core miRNAs using overlapping analyses. These RNAs may represent potential therapeutic targets for the treatment of OA.

Interactions Among lncRNA/circRNA, miRNA, and mRNA in Musculoskeletal Degenerative Diseases

Musculoskeletal degenerative diseases (MSDDs) are pathological conditions that affect muscle, bone, cartilage, joint and connective tissue, leading to physical and functional impairments in patients, mainly consist of osteoarthritis (OA), intervertebral disc degeneration (IDD), rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) are novel regulators of gene expression that play an important role in biological regulation, involving in chondrocyte proliferation and apoptosis, extracellular matrix degradation and peripheral blood mononuclear cell inflammation. Research on MSDD pathogenesis, especially on RA and AS, is still in its infancy and major knowledge gaps remain to be filled. The effects of lncRNA/circRNA-miRNA-mRNA axis on MSDD progression help us to fully understand their contribution to the dynamic cellular processes, provide the potential OA, IDD, RA and AS therapeutic strategies. Further studies are needed to explore the mutual regulatory mechanisms between lncRNA/circRNA regulation and effective therapeutic interventions in the pathology of MSDD.

Genomic Instability-Related LncRNA Signature Predicts the Prognosis and Highlights LINC01614 Is a Tumor Microenvironment-Related Oncogenic lncRNA of Papillary Thyroid Carcinoma

Background

Genomic instability (GI) is among the top ten characteristics of malignancy. Long non-coding RNAs (lncRNAs) are promising cancer biomarkers that are reportedly involved in GI. So far, the clinical value of GI-related lncRNAs (GIlncs) in papillary thyroid cancer (PTC) has not been clarified.

Methods

Integrative analysis of lncRNA expression and somatic mutation profiles was performed to identify GIlncs. Analysis of differentially expressed lncRNAs in the group with high- and low- cumulative number of somatic mutations revealed significant GIlncs in PTC. Univariate and multivariate Cox proportional hazard regression analyses were performed to identify hub-GIlncs.

Results

A computational model based on four lncRNAs (FOXD2-AS1, LINC01614, AC073257.2, and AC005082.1) was identified as a quantitative index using an in-silicon discovery cohort. GILS score was significantly associated with poor prognosis, as validated in the TCGA dataset and further tested in our local RNA-Seq cohort. Moreover, a combination of clinical characteristics and the composite GILS-clinical prognostic nomogram demonstrates satisfactory discrimination and calibration. Furthermore, the GILS score and FOXD2-AS1, LINC01614, AC073257.2, and AC005082.1 were also associated with driver mutations and multiple clinical-pathological variables, respectively. Moreover, RNA-Seq confirmed the expression patterns of FOXD2-AS1, LINC01614, AC073257.2, and AC005082.1 in PTC and normal thyroid tissues. Biological experiments demonstrated that downregulated or overexpressed LINC01614 affect PTC cell proliferation, migration, and invasion in vitro. Activation of the stromal and immune cell infiltration was also observed in the high LINC01614 group in the PTC microenvironment.

Conclusion

In summary, we identified a signature for clinical outcome prediction in PTC comprising four lncRNAs associated with GI. A better understanding of the GI providing an alternative evaluation of the progression risk of PTC. Our study also demonstrated LINC01614 as a novel oncogenic lncRNA and verified its phenotype in PTC.

Long noncoding RNA LINC00184 facilitates the proliferation, metastasis, and adenine metabolism of cholangiocarcinoma via modulating hsa-miR-23b-3p/ANXA2 axis

The purpose of this article was to probe the mechanism underlying long noncoding RNA (lncRNA)-LINC00184 in cholangiocarcinoma development and to investigate the effects of LINC00184 on cholangiocarcinoma. We used bioinformatics to analyze the expression of LINC00184, microRNA (miR)-23b-3p and ANXA2 in cholangiocarcinoma tissues. The levels of LINC00184, miR-23b-3p, and ANXA2 were detected by qRT-PCR. Cell proliferation was tested by CCK8. Transwell assay was used to detect cell invasion and migration. The target connection between LINC00184, miR-23b-3p, or ANXA2 was probed by luciferase reporter assay. RNA pull-down method was employed to test the relationship among LINC00184/miR-23b-3p/ANXA2 in cholangiocarcinoma cells. The Pearson correlation coefficient analyzed was applied to analyze the correlation among LINC00184, miR-23b-3p, and ANXA2. LC-MS/M analysis was used to explore whether the changes of adenine metabolism was affected by LINC00184 in cholangiocarcinoma cells. We discovered that LINC00184 expression was heightened in cholangiocarcinoma patients and cells. Knockdown of LINC00184 repressed cell proliferation, invasion, migration and adenine metabolism in cholangiocarcinoma cells. miR-23b-3p was regarded as a target of LINC00184 and its depletion perversed the inhibitive influence of LINC00184 silencing on cholangiocarcinoma cells. ANXA2 was a target of miR-23b-3p and was negatively modulated by miR-23b-3p. Moreover, ANXA2 was positively modulated by LINC00184 via sponging miR-23b-3p. In short, silencing of LINC00184 suppressed cell proliferation, invasion and migration through over-expression of miR-23b-3p and reducing of ANXA2 in cholangiocarcinoma cells. These findings contribute to understanding the influences of LINC00184, miR-23b-3p, and ANXA2 on cholangiocarcinoma and provide basis for cholangiocarcinoma treatment.

Bone marrow mesenchymal stem cell-derived exosomal miR-206 promotes osteoblast proliferation and differentiation in osteoarthritis by reducing Elf3

MicroRNAs (miRNAs) serve as gene silencers involved in essential cell functions. The role of miR‐206 and E74‐like factor 3 (Elf3) has been identified in osteoarthritis (OA), while the effect of exosomal miR‐206 from bone marrow mesenchymal stem cells (BMSCs) in OA remains largely unknown. Thus, we aim to explore the role of exosomal miR‐206 from BMSCs in OA with the involvement of Elf3. BMSCs and BMSC‐derived exosomes (BMSC‐exos) were obtained and identified. OA mouse models were constructed by anterior cruciate ligament transection and then treated with BMSC‐exos or BMSC‐exos containing miR‐206 mimic/inhibitor. The expression of miR‐206, Elf3, inflammatory factors, osteocalcin (OCN) and bone morphogenetic protein 2 (BMP2) in mouse femoral tissues was assessed. The pathological changes in mouse femur tissues were observed. The mouse osteoblasts were identified and treated with untransfected or transfected BMSC‐exos, and then, the expression of miR‐206, Elf3, OCN and BMP2 was determined. The alkaline phosphatase (ALP) activity, calcium deposition level, OCN secretion, proliferation, apoptosis and cell cycle arrest in osteoblasts were measured. MiR‐206 was down‐regulated while Elf3 was up‐regulated in OA animal and cellular models. Exosomal miR‐206 ameliorated inflammation and increased expression of OCN and BMP2 in mouse femoral tissues. Moreover, exosomal miR‐206 promoted ALP activity, calcium deposition level, OCN secretion and proliferation and inhibited apoptosis in OA osteoblasts. Overexpressed Elf3 reversed miR‐206 up‐regulation‐induced effects on OA osteoblasts. BMSC‐derived exosomal miR‐206 promotes proliferation and differentiation of osteoblasts in OA by reducing Elf3. Our research may provide novel targets for OA treatment.

LncRNA DNM3OS regulates GREM2 via miR-127-5p to suppress early chondrogenic differentiation of rat mesenchymal stem cells under hypoxic conditions

Background

Improved chondrogenic differentiation of mesenchymal stem cells (MSCs) by genetic regulation is a potential method for regenerating articular cartilage. MiR-127-5p has been reported to promote cartilage differentiation of rat bone marrow MSCs (rMSCs); however, the regulatory mechanisms underlying hypoxia-stimulated chondrogenic differentiation remain unknown.

Methods

rMSCs were induced to undergo chondrogenic differentiation under normoxic or hypoxic conditions. Expression of lncRNA DNM3OS, miR-127-5p, and GREM2 was detected by quantitative real-time PCR. Proteoglycans were detected by Alcian blue staining. Western blot assays were performed to examine the relative levels of GREM2 and chondrogenic differentiation related proteins. Luciferase reporter assays were performed to assess the association among DNM3OS, miR-127-5p, and GREM2.

Results

MiR-127-5p levels were upregulated, while DNM3OS and GREM2 levels were downregulated in rMSCs induced to undergo chondrogenic differentiation, and those changes were attenuated by hypoxic conditions (1% O₂). Further in vitro experiments revealed that downregulation of miR-127-5p reduced the production of proteoglycans and expression of chondrogenic differentiation markers (COL1A1, COL2A1, SOX9, and ACAN) and osteo/chondrogenic markers (BMP-2, p-SMAD1/2). MiR-127-5p overexpression produced the opposite results in rMSCs induced to undergo chondrogenic differentiation under hypoxic conditions. GREM2 was found to be a direct target of miR-127-5p, which was suppressed in rMSCs undergoing chondrogenic differentiation. Moreover, DNM3OS could directly bind to miR-127-5p and inhibit chondrogenic differentiation of rMSCs via regulating GREM2.

Conclusions

Our study revealed a novel molecular pathway (DNM3OS/miR-127-5p/GREM2) that may be involved in hypoxic chondrogenic differentiation.

LncRNA FOXD2-AS1 promotes cell proliferation and invasion of fibroblast-like synoviocytes by regulation of miR-331-3p/PIAS3 pathway in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disorder that leads to systemic inflammation of diarthrodial joint, synovial hyperplasia, cartilage damage, and ultimately joint destruction and deformity. As the dominant non-immune cells in the synovium, fibroblast-like synoviocytes (FLSs) significantly contribute to the deterioration of RA. Our study aimed to explore the regulatory role of long non-coding RNA FOXD2-AS1 in RA progression. Compared to patients with joint trauma, the expression of FOXD2-AS1 was elevated in serum and synovial tissue samples of RA patients. FOXD2-AS1 knockdown inhibited the proliferation and invasion of rheumatoid FLSs but restored their apoptotic ability. Furthermore, FOXD2-AS1 acted as a sponge for microRNA (miR)-331-3p. The expressions of FOXD2-AS1 and miR-331-3p in synovial tissues of RA patients were negatively correlated. Protein inhibitor of activated STAT 3 (PIAS3) was predicted as a downstream target of miR-331-3p. The expressions of FOXD2-AS1 and PIAS3 in synovial tissues of RA patients were positively correlated, whereas a negative correlation was observed between the levels of miR-331-3p and PIAS3. Moreover, increased proliferation and invasion of rheumatoid FLSs induced by FOXD2-AS1 overexpression was inhibited by the knockdown of PIAS3. In summary, this study demonstrated that FOXD2-AS1 promoted RA progression via regulating the miR-331-3p/PIAS3 pathway, suggesting that therapeutic strategies based on the FOXD2-AS1/miR-331-3p/PIAS3 axis may represent a promising treatment approach for RA patients.

Roles of long non‑coding RNA in osteoarthritis (Review)

Osteoarthritis (OA) is a chronic bone and joint disease characterized by articular cartilage degeneration and joint inflammation and is the most common form of arthritis. The clinical manifestations of OA are chronic pain and joint activity disorder, which severely affect the patient quality of life. Long non-coding RNA (lncRNA) is a class of RNA molecules >200 nucleotides long that are expressed in animals, plants, yeast, prokaryotes and viruses. lncRNA molecules lack an open reading frame and are not translated into protein. The present review collated the results of recent studies on the role of lncRNA in the pathogenesis of OA to provide information for the prevention, diagnosis and treatment of OA.

Knockdown of long non-coding RNA KCNQ1OT1 suppresses the progression of osteoarthritis by mediating the miR-211-5p/TCF4 axis in vitro

Numerous studies have reported the critical roles of long non-coding RNAs (lncRNAs) in the regulation of osteoarthritis (OA) development. The present study aimed to assess the function and regulatory mechanism of a lncRNA, KCNQ1 opposite strand/antisense transcript 1 (KCNQ1OT1), in OA in vitro. C28/I2 cells were treated with lipopolysaccharide (LPS) to generate an in vitro OA model. The relative expression levels of KCNQ1OT1, microRNA (miR)-211-5p and transcription factor 4 (TCF4) were determined via reverse transcription-quantitative polymerase chain reaction. The associations between KCNQ1OT1, miR-211-5p and TCF4 were confirmed using a dual-luciferase reporter assay. Furthermore, cell viability was assessed using the MTT assay. Inflammatory cytokine levels were measured using ELISA. The protein expression levels of matrix metalloproteinase-3/13, collagen II/X and TCF4 were detected by western blotting. KCNQ1OT1 and TCF4 were highly expressed in the cartilage tissues of patients with OA and C28/I2 cells treated with LPS (OA cells), whereas miR-211-5p was downregulated concomitantly in OA tissues and cells. Knockdown of KCNQ1OT1 stimulated cell viability, and suppressed the inflammation and degradation of the extracellular matrix (ECM) in OA cells. In addition, overexpression of miR-211-5p stimulated cell viability, and inhibited inflammation and degradation of the ECM in OA cells. Notably, miR-211-5p was revealed to be the target of, and was negatively regulated by, KCNQ1OT1. TCF4 was targeted and negatively modulated by miR-211-5p. Transfection of cells with the miR-211-5p inhibitor or pcDNA-TCF4 reversed the suppressive effects of short hairpin RNA (sh)-KCNQ1OT1 on inflammation and ECM degradation, as well as the promotive effect of sh-KCNQ1OT1 on viability in OA in vitro. Therefore, KCNQ1OT1 may regulate the miR-211-5p/TCF4 axis to ameliorate OA in vitro.

RNA Sequencing Reveals LINC00167 as a Potential Diagnosis Biomarker for Primary Osteoarthritis: A Multi-Stage Study

Objectives

Given the roles played by lncRNA in human diseases and the high incidence of OA, this study investigated the pivotal pathways involved in the disease and identified potential biomarkers for OA diagnosis.

Methods

We first performed an exploration of RNA-sequencing in peripheral blood leukocytes from six subjects (3 OA and 3 healthy controls). Promising candidate lncRNAs were evaluated in first stage validation using a GEO dataset (GSE114007) of 38 subjects (20 OA and 18 healthy controls), followed by a second stage validation using quantitative PCR analysis with 101 subjects (67 OA and 34 controls). The third stage investigated the potential value of validated lncRNA in the early diagnosis of OA in peripheral blood leukocytes from a total of 120 participants (60 cases and 60 controls).

Results

The dataset identified a total of 1,380 up-regulated and 719 down-regulated mRNAs and 5,743 up-regulated and 7,384 down-regulated lncRNAs. The up-regulated DEGs were mainly enriched in the extracellular matrix, while the down-regulated DEGs were mainly enriched in the IL-17 and wnt signaling pathways. 18 overlapping candidate lncRNAs survived after first-stage validation. 3 hub lncRNAs were selected for the second validation stage and qualified in an external sample, and lncRNA LINC00167 was further confirmed with a similar result (down-expressed in both stages). Receiver operating characteristic analysis showed that LINC00167 can distinguish OA cases from healthy controls with a high area under the curve of 0.879 (95%CI: 0.819, 0.938; P < 0.001), with a sensitivity of 80.7% and specificity of 83.5%.

Conclusion

The expression profile of OA was identified and critical pathways were elucidated by an integrated approach to RNA-seq from easily accessible blood. LINC00167 may serve as a potential early diagnosis marker for OA in clinical practice. The detailed mechanism of action of this lncRNA requires further elucidation in future studies.

Forkhead box D1 promotes EMT and chemoresistance by upregulating lncRNA CYTOR in oral squamous cell carcinoma

Chemotherapy regimens containing cisplatin remain the first-line treatments for patients with oral squamous cell cancer (OSCC); however, the treatment effect is often transient because of chemoresistance and recurrence. Understanding the mechanisms of chemoresistance in OSCC might provide novel targetable vulnerabilities. In the present study, we revealed that Forkhead box D1 (FOXD1) is upregulated in OSCC and predicted poor prognosis. Moreover, ectopic expression of FOXD1 promoted, while silencing of FOXD1 inhibited, the epithelial-mesenchymal transition (EMT) and chemoresistance of OSCC, both in vitro and in vivo. Mechanistically, FOXD1 binds to the promoter of long non-coding RNA Cytoskeleton Regulator RNA (CYTOR) and activates its transcription. CYTOR then acts as a competing endogenous RNA to inhibit miR-1252-5p and miR-3148, thus upregulating lipoma preferred partner (LPP) expression. Importantly, the CYTOR/LPP axis was proven to be essential for FOXD1-induced EMT and chemoresistance in OSCC. These findings reveal a novel mechanism for the chemotherapy resistance of OSCC, suggesting that FOXD1 might be a potential prognostic marker and anti-resistance therapeutic target.

Identification and Characterization of the Intra-Articular Microbiome in the Osteoarthritic Knee

Osteoarthritis (OA) is the most common joint disorder in the United States, and the gut microbiome has recently emerged as a potential etiologic factor in OA development. Recent studies have shown that a microbiome is present at joint synovia. Therefore, we aimed to characterize the intra-articular microbiome within osteoarthritic synovia and to illustrate its role in OA disease progression. RNA-sequencing data from OA patient synovial tissue was aligned to a library of microbial reference genomes to identify microbial reads indicative of microbial abundance. Microbial abundance data of OA and normal samples was compared to identify differentially abundant microbes. We computationally explored the correlation of differentially abundant microbes to immunological gene signatures, immune signaling pathways, and immune cell infiltration. We found that microbes correlated to OA are related to dysregulation of two main functional pathways: increased inflammation-induced extracellular matrix remodeling and decreased cell signaling pathways crucial for joint and immune function. We also confirmed that the differentially abundant and biologically relevant microbes we had identified were not contaminants. Collectively, our findings contribute to the understanding of the human microbiome, well-known OA risk factors, and the role microbes play in OA pathogenesis. In conclusion, we present previously undiscovered microbes implicated in the OA disease progression that may be useful for future treatment purposes.

[Regulation of long non-coding RNA in cartilage injury of osteoarthritis]

Objective

To summarize the regulatory effect of long non-coding RNA (lncRNA) on osteoarthritis (OA) cartilage injury.

Methods

The molecular functions and mechanisms of lncRNA were introduced and its regulatory effects on the pathological processes of OA were elaborated by referring to the relevant literature at domestic and abroad in recent years.

Results

The pathological characteristics of OA are degeneration of articular cartilage and inflammation of synovial tissue, but its etiology and pathological mechanism have not been clarified. lncRNA is a kind of heterogeneous non-coding RNA, which plays a regulatory role in many inflammation-related diseases and exerts a wide range of biological functions. lncRNA is a regulator involved in the pathogenesis of OA, and is abnormally expressed in OA cartilage, leading to the degeneration of the extracellular matrix of cartilage.

Conclusion

At present, there have been preliminary studies on the pathological effects of lncRNA in regulating OA and the biological functions of chondrocytes. However, the pathogenesis of lncRNA and its regulatory network in OA and the way in which it regulates inflammatory pathways are still unclear, and further exploration is needed.

Activation of LncRNA FOXD2-AS1 by H3K27 acetylation regulates VEGF-A expression by sponging miR-205-5p in recurrent pterygium

LncRNA FOXD2‐AS1 is abnormally expressed in many diseases. However, the molecular mechanisms whereby FOXD2‐AS1 is involved in recurrent pterygium remain unknown. Here, qRT‐PCR was performed to quantify FOXD2‐AS1 expression, while CCK‐8, flow cytometer and neoplasm xenograft assays were used to investigate its function. Dual‐luciferase reporter, RIP and RNA pull‐down assays were conducted to address the relationship between FOXD2‐AS1, miR‐205‐5p and VEGF‐A, while ChIP assays were used to detect H3K27 acetylation at the FOXD2‐AS1 promoter. FOXD2‐AS1 expression was up‐regulated in recurrent pterygium tissues. Moreover, a high FOXD2‐AS1 expression was associated with advanced stages, increased microvessel density and shorter recurrent‐free survival. In addition, ROC analysis showed that FOXD2‐AS1 is a valid predictor of recurrent pterygium. Furthermore, we show that FOXD2‐AS1 induced proliferation and inhibited apoptosis in a cell line derived from recurrent pterygia (HPF‐R) at least partially through the regulation of the miR‐205‐VEGF pathway. In addition, the up‐regulation of FOXD2‐AS1 was attributed to the H3K27 acetylation at the promoter region. In conclusion, FOXD2‐AS1 is activated via its H3K27 acetylation and regulates VEGF‐A expression by sponging miR‐205‐5p in recurrent pterygium. Our results may provide a basis for the development of new therapeutic targets and biomarkers for recurrent pterygium.

Knockdown of exosome‑mediated lnc‑PVT1 alleviates lipopolysaccharide‑induced osteoarthritis progression by mediating the HMGB1/TLR4/NF‑κB pathway via miR‑93‑5p

Osteoarthritis is a chronic degenerative joint disease. Long non‑coding RNA plasmacytoma variant translocation 1 (PVT1) is involved in the progression of osteoarthritis and exosomes serve a central role in intercellular communication. However, whether PVT1 can be mediated by exosomes in osteoarthritis has not been reported. Whole blood was drawn from osteoarthritis patients and healthy volunteers. Lipopolysaccharide (LPS) was used to stimulate human normal chondrocytes (C28/I2) to construct a cell damage model in vitro. Protein levels were examined via western blot analysis. eThe expression of PVT1, microRNA (miR)‑93‑5p and high mobility groupprotein B1 (HMGB1) was evaluated through reverse transcription‑quantitative PCR. Cell viability and apoptosis were determined through CCK‑8 or flow cytometric assay. Inflammatory cytokines were measured via ELISA. The relationship between PVT1 or HMGB1 and miR‑93‑5p was confirmed by dual‑luciferase reporter assay. PVT1, HMGB1 and exosomal PVT1 were upregulated while miR‑93‑5p was downregulated in osteoarthritis patient serum and LPS‑induced C28/I2 cells. Exosomes from osteoarthritis patient serum and LPS‑treated C28/I2 cells increased PVT1 expression in C28/I2 cells. PVT1 depletion reversed the decrease of viability and the increase of apoptosis, inflammation responses and collagen degradation of C28/I2 cells induced by LPS. PVT1 regulated HMGB1 expression via sponging miR‑93‑5p. miR‑93‑5p inhibition abolished PVT1 silencing‑mediated viability, apoptosis, inflammation responses and collagen degradation of LPS‑stimulated C28/I2 cells. HMGB1 increase overturned miR‑93‑5p upregulation‑mediated viability, apoptosis, inflammation responses and collagen degradation of LPS‑stimulated C28/I2 cells. Furthermore, PVT1 modulated the Toll‑like receptor 4/NF‑κB pathway through an miR‑93‑5p/HMGB1 axis. In summary, exosome‑mediated PVT1 regulated LPS‑induced osteoarthritis progression by modulating the HMGB1/TLR4/NF‑κB pathway via miR‑93‑5p, providing a new route for possible osteoarthritis treatment.

LncRNA NEAT1 regulates chondrocyte proliferation and apoptosis via targeting miR-543/PLA2G4A axis

Osteoarthritis (OA), which is characterized by articular cartilage degeneration, shows a gradually increasing incidence with age. This study explored the molecular mechanism underlying the proliferation and apoptosis of chondrocytes during OA progression. In this study, chondrocytes were isolated from human knee cartilages. The targeted relationship among nuclear enriched abundant transcript 1 (NEAT1), microRNA-543 (miR-543) and PLA2G4A was predicted on TargetScan V7.2 and starBase and validated by performing dual-luciferase reporter assay. High-expressed NEAT1 was detected in OA cartilage and chondrocytes. NEAT1 was negatively correlated with miR-543 and was low-expressed in OA cartilage and PLA2G4A was negatively correlated with miR-543 and was high-expressed in OA cartilage. In OA chondrocytes, the overexpressed NEAT1 inhibited the expressions of p-Akt1 and Bcl-2 and upregulated that of matrix metalloprotease (MMP)-3, MMP-9, MMP-13, interleukin (IL)-6 and IL-8, but such effects of overexpressed NEAT1 were reversed by miR-543 mimic. SiRNA-NEAT1 exerted an opposite effect to NEAT1 overexpression on OA chondrocytes, but this could be reversed by miR-543 inhibitor. The effect of PLA2G4A overexpression was the opposite to miR-543 mimic on OA chondrocytes. In conclusion, NEAT1 could sponge miR-543 to induce PLA2G4A expression, inhibit chondrocyte proliferation and promote apoptosis.

The emerging role of lncRNAs in chondrocytes from osteoarthritis patients

Long non-coding RNAs (lncRNAs) play important roles in many physiological and pathological processes, including osteoarthritis (OA). Recent studies have demonstrated that lncRNAs are involved in the pathogenesis of OA by affecting various essential cellular features of chondrocytes, such as proliferation, apoptosis, inflammation, and degradation of the extracellular matrix (ECM). However, there are only a limited number of studies in this area, indicating that the role of lncRNAs in OA may have been overlooked. The aim of this literature review is to summarize the versatile roles and molecular mechanisms of lncRNAs in chondrocytes involved in OA. At the end of this article, the function of the lncRNA HOX transcript antisense RNA (HOTAIR) in chondrocytes in OA is highlighted. Because lncRNAs affect proliferation, apoptosis, inflammatory responses, and ECM degradation by chondrocytes in OA, they may serve as potential biomarkers or therapeutic targets for the diagnosis or treatment of OA. The specific role and related mechanisms of lncRNAs in OA warrants further investigation.

LncRNA-H19 silencing suppresses synoviocytes proliferation and attenuates collagen-induced arthritis progression by modulating miR-124a

Objectives

Long non-coding RNA H19 (lncRNA-H19) is highly expressed in fibroblast-like synoviocytes (FLS) from patients with RA. The present study aimed to clarify the pathological significance and regulatory mechanisms of lncRNA-H19 in FLS.

Methods

Mice with CIA were locally injected with LV-shH19. The progression of CIA was explored by measuring arthritic index (AI), paw thickness (PT) and histologic analysis. The growth and cell cycle of human synoviocyte MH7A were assessed by CCK-8 and flow cytometric analysis. The putative binding sites between lncRNA-H19 and miR-124a were predicted online, and the binding was identified by luciferase assay. RT-qPCR, Western blot and luciferase assay were performed to explore the molecular mechanisms between liver X receptor (LXR), lncRNA-H19, miR-124a and its target genes.

Results

The expression of lncRNA-H19 was closely associated with the proliferation of synoviocytes and knockdown of lncRNA-H19 significantly ameliorated the progression of CIA, reflected by decreased AI, PT and cartilage destruction. Notably, lncRNA-H19 competitively bound to miR-124a, which directly targets CDK2 and MCP-1. It was confirmed that lncRNA-H19 regulates the proliferation of synoviocytes by acting as a sponge of miR-124a to modulate CDK2 and MCP-1 expression. Furthermore, the agonists of LXR inhibited lncRNA-H19-mediated miR-124a-CDK2/MCP-1 signalling pathway in synoviocytes. The ‘lncRNA-H19-miR-124a-CDK2/MCP-1’ axis plays an important role in LXR anti-arthritis.

Conclusion

Regulation of the miR-124a-CDK2/MCP-1 pathway by lncRNA-H19 plays a crucial role in the proliferation of FLS. Targeting this axis has therapeutic potential in the treatment of RA and may represent a novel strategy for RA treatment.

The Therapeutic Potential and Role of miRNA, lncRNA, and circRNA in Osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a disease characterized by progressive degeneration, joint hyperplasia, narrowing of joint spaces, and extracellular matrix metabolism. Recent studies have shown that the pathogenesis of OA may be related to non-coding RNA, and its pathological mechanism may be an effective way to reduce OA.

OBJECTIVE

The purpose of this review was to investigate the recent progress of miRNA, long noncoding RNA (lncRNA) and circular RNA (circRNA) in gene therapy of OA, discussing the effects of this RNA on gene expression, inflammatory reaction, apoptosis and extracellular matrix in OA.

METHODS

The following electronic databases were searched, including PubMed, EMBASE, Web of Science, and the Cochrane Library, for published studies involving the miRNA, lncRNA, and circRNA in OA. The outcomes included the gene expression, inflammatory reaction, apoptosis, and extracellular matrix.

RESULTS AND DISCUSSION

With the development of technology, miRNA, lncRNA, and circRNA have been found in many diseases. More importantly, recent studies have found that RNA interacts with RNA-binding proteins to regulate gene transcription and protein translation, and is involved in various pathological processes of OA, thus becoming a potential therapy for OA.

CONCLUSION

In this paper, we briefly introduced the role of miRNA, lncRNA, and circRNA in the occurrence and development of OA and as a new target for gene therapy.

Role of MicroRNA, LncRNA, and Exosomes in the Progression of Osteoarthritis: A Review of Recent Literature

Osteoarthritis (OA) is a common clinical degenerative disease characterized by the destruction of articular cartilage, which has an increasing impact on people's lives and social economy. The pathogenesis of OA is complex and unclear, and there is no effective way to block its progress. The study of the pathogenesis of OA is the prerequisite for the early diagnosis and effective treatment of OA. To define the pathogenesis of OA, this review considers the pathological mechanism of OA that involves microRNA, lncRNA, and exosomes. More and more evidence shows that microRNA, lncRNA, and exosomes are closely related to OA. MicroRNA inhibits the target gene by binding to the 3'- untranslated region of the targets. LncRNA usually competes with microRNA to regulate the expression level of downstream genes, while exosomes, as a carrier of intercellular information transfer, transmit the biological information of mother cells to target cells, and the effect of exosomes secreted by different cells on OA are different. In this review, we emphasized that different microRNA, lncRNA, and exosomes have different regulatory effects on chondrocyte proliferation and apoptosis, extracellular matrix degradation and inflammation. Besides, we classified and analyzed these molecules according to their effects on the progress of OA. Based on the analysis of the reported literature, this review reveals some pathogenesis of OA, and emphasizes that microRNA, lncRNA, and exosomes have great potential to assist early diagnosis and effective treatment of OA.

Network Pharmacology Approach to Uncover the Mechanism Governing the Effect of Radix Achyranthis Bidentatae on Osteoarthritis

BACKGROUND

This study used a network pharmacology approach to elucidate the molecular mechanism governing the effect of Radix Achyranthis Bidentatae (RAB) on osteoarthritis (OA).

METHODS

Based on oral bioavailability and drug-likeness, the main active components of RAB were screened via the Traditional Chinese Medicine Systems Pharmacology platform. The GeneCard, OMIM, PharmGkb, Therapeutic Targets database, and DrugBank database were used to establish a database of osteoarthritis targets. The interactive active network map of "ingredient-target" was constructed with Cytoscape software (Version 3.7.1). The protein-protein interaction network was constructed with the STRING database, and the related protein interaction relationship was analysed. GO biological function analysis and KEGG enrichment analysis for core targets were performed. Finally, docking of the active components with the core target was carried out.

RESULTS

Sixteen active components of RAB were obtained, and 63 potential targets for OA were identified. Network analysis results indicate that these targets are primarily involved in regulating biological processes, such as cell metabolism, apoptosis, and cell proliferation. Pathways involved in the treatment of osteoarthritis include virus-related signalling pathways, apoptosis signalling pathways, IL-17 signalling pathways, and PI3K/AKT signalling pathways.

CONCLUSION

RAB has the characteristics of being multi-system, multi-component and multi-target. Possible mechanisms of action for RAB include regulating the immune and inflammatory responses, reducing chondrocyte apoptosis, and protecting the joint synovial membrane and cartilage to control disease development. The active ingredients in RAB, such as sterols and flavonoids, exhibit strong potential as candidate drugs for the treatment of osteoarthritis.

Long non-coding RNA SNHG15 is a competing endogenous RNA of miR-141-3p that prevents osteoarthritis progression by upregulating BCL2L13 expression

Increasing evidence has demonstrated that the dysregulated expression of long noncoding RNAs (lncRNAs) has important roles in the progression of osteoarthritis (OA), but the function of the lncRNA SNHG15 remains unclear. In the present study, we observed that SNHG15 was downregulated in OA cartilage tissues and IL-1β-induced chondrocytes. The lower expression of SNHG15 was negatively associated with the observed modified Mankin scale scores, extracellular matrix (ECM) degradation and chondrocyte apoptosis. Downregulated expression of SNHG15 increased chondrocyte viability and decreased chondrocyte apoptosis and ECM degradation in vitro and reduced damage to articular cartilage in vivo. Mechanistically, we demonstrated that SNHG15 overexpression promotes the expression of BCL2L13 by sponging miR-141-3p. The higher expression of miR-141-3p was negatively correlated with SNHG15 and BCL2L13 levels in OA cartilage tissues, and a positive correlation was also shown between SNHG15 and BCL2L13 levels. Furthermore, ectopic expression of miR-141-3p or knockdown of BCL2L13 expression could both reduce the effects of SNHG15 on chondrocyte proliferation, apoptosis and ECM degradation. Collectively, these findings reveal that SNHG15 inhibits OA progression by acting as an miR-141-3p sponge to promote BCL2L13 expression, suggesting that knockdown of SNHG15 expression in chondrocytes can be a potential therapeutic strategy to ameliorate OA progression.

lncRNA FOXD2-AS1 affects trophoblast cell proliferation, invasion and migration through targeting miRNA

The abnormal expression of lncRNAs and miRNAs has been found in the placentas of patients with preeclampsia (PE). Therefore, we determined the role of lncRNA FOXD2-AS1/miR-3127 in trophoblast cells. The expression of lncRNA FOXD2-AS1 was detected by qRT-PCR. The proliferation, migration and invasion ability of trophoblast cells were evaluated using CCK-8, wound healing and transwell assays. The target gene of lncRNA FOXD2-AS1 was determined by StarBase and luciferase reporter assays. Western blotting was used to analyze the expression of matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 9 (MMP9). The results showed that FOXD2-AS1 affected trophoblast cell viability in vitro, while the expression of miR-3127 was decreased. FOXD2-AS1 silencing decreased the promotion effects on trophoblast cell induced by miR-3127 inhibition. In addition, FOXD2-AS1 and miR-3127 presented the same effect on MMP2 and MMP9 levels. lncRNA FOXD2-AS1 modulated trophoblast cell proliferation, invasion and migration through downregulating miR-3127 expression. Therefore, lncRNA FOXD2-AS1 could act as a latent therapeutic marker in preeclampsia.

Noncoding RNAs: New regulatory code in chondrocyte apoptosis and autophagy

Osteoarthritis (OA) is a bone and joint disease characterized by progressive cartilage degradation. In the face of global trends of population aging, OA is expected to become the fourth most common disabling disease by 2020. Nevertheless, the detailed pathogenesis of OA has not yet been elucidated. Noncoding RNAs (ncRNAs), including long noncoding RNAs, microRNAs, and circular RNAs, do not encode proteins but have recently emerged as important regulators of apoptosis and autophagy of chondrocytes, thereby highlighting a potential role in chondrocyte injury leading to OA onset and progression. We here review recent findings on these regulatory roles of ncRNAs to provide new directions for research on the pathogenesis of OA and offer new therapeutic targets for prevention and treatment. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA in Disease and Development > RNA in Development.

Inhibition of Long Non-coding RNA CTD-2574D22.4 Alleviates LPS-induced Apoptosis and Inflammatory Injury of Chondrocytes

Background:

Osteoarthritis (OA) is a common joint disease characterized by cartilage degeneration. Long non-coding RNAs (lncRNAs) have been associated with inflammatory diseases, including OA. Here, we investigated the potential molecular role of lncRNAs in OA pathogenesis.

Methods:

ATDC5 cells were treated with lipopolysaccharides (LPS), and qPCR was used to identify and determine expression of potential lncRNAs involved in LPS-induced chondrocyte injury. Cell viability, apoptosis, and expression of cartilage-related genes and inflammatory cytokines were assessed after CTD-2574D22.4 knockdown.

Results:

After LPS stimulation, CTD-2574D22.4 was found to be the second highest up-regulated gene, and the enhanced expression was validated in OA chondrocytes. Moreover, CTD-2574D22.4 inhibition significantly rescued cell viability, suppressed by LPS stress, and markedly attenuated LPS-induced apoptosis. The expression of cartilage-degrading enzymes MMP-13 and ADAMTS-5 were increased, while type II collagen was reduced after LPS treatment. This trend was largely reversed by CTD-2574D22.4 knockdown. Additionally, mRNA and protein levels of key inflammatory cytokines (TNF-a, IL-6, and IL-1β) were significantly elevated in the LPS group and partially relieved upon CTD-2574D22.4 knockdown.

Conclusion:

CTD2574D22.4 knockdown ameliorates LPS-induced cartilage injury by protecting chondrocytes from apoptosis via anti-inflammation and anti- cartilage-degrading pathways. Thus, CTD2574D22.4 might be a potential diagnostic and therapeutic target for OA.

LncRNA MALAT1 promotes osteoarthritis by modulating miR-150-5p/AKT3 axis

BACKGROUND

Many studies have reported that long noncoding RNAs (lncRNAs) could act as sponges for microRNAs (miRNAs) and play important roles in the regulation of osteoarthritis (OA). Yet, the underlying mechanisms of lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in OA are still unclear. Therefore, we aimed to explore the regulation mechanisms of MALAT1 in OA procession.

METHODS

IL-1β treatment in chondrocyte was used to mimic OA in vitro. MALAT1, miR-150-5p and AKT3 expression levels were detected via qRT-PCR. The protein levels of AKT3, MMP-13, ADAMTS-5, Bax, Bcl-2, cleaved-PARP, collagen II and aggracan were measured by western blot. MTT assay was performed to detect cell proliferation ability. The apoptosis of chondrocytes was determined using flow cytometry and western blot. Luciferase assay and RNA immunoprecipitation (RIP) assays were used to confirm the relationship among MALAT1, miR-150-5p and AKT3.

RESULTS

In our study, MALAT1 and AKT3 were upregulated while miR-150-5p was downregulated in OA in vitro and vivo. The level of miR-150-5p was negatively correlated with that of MALAT1 or AKT3. More importantly, overexpression of MALAT1 promoted the expression of AKT3 by negatively regulating miR-150-5p. MALAT1 knockdown inhibited cell proliferation, promoted apoptosis, increased MMP-13, ADAMTS-5 expression and decreased collagen II, aggracan expression in IL-1β treated chondrocytes. MALAT1 upregulation or AKT3 overexpression enhanced proliferation, inhibited apoptosis and extracellular matrix (ECM) degradation, which was undermined by overexpression of miR-150-5p. By contrast, miR-150-5p depletion rescued the effect of MALAT1 downregulation or loss of AKT3 on IL-1β-stimulated chondrocytes.

CONCLUSION

MALAT1 was responsible for cell proliferation, apoptosis, and ECM degradation via miR-150-5p/AKT3 axis.