LncRNA DNM3OS promotes proliferation and inhibits apoptosis through modulating IGF1 expression by sponging MiR-126 in CHON-001 cells

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.

DNM3OS Enhances the Apoptosis and Senescence of Spermatogonia Associated with Nonobstructive Azoospermia by Providing miR-214-5p and Decreasing E2F2 Expression

Background

Nonobstructive azoospermia (NOA) is a complex disease characterized by the spermatogenic dysfunction of testicular tissues. The roles played by long noncoding RNAs (lncRNAs) in NOA pathogenesis have not been extensively studied.

Methods

Microarray assays were performed on samples of testicular biopsy tissue obtained from patients with NOA for the purpose of identifying differentially expressed lncRNAs and messenger RNA (mRNA) transcripts, and the results were verified by quantitative real-time polymerase chain reaction. Mouse-derived GC-1 spermatogonia (spg) cells undergoing treatment with Adriamycin (ADR) were used to investigate the biological functions of the selected lncRNAs in vitro. The target microRNAs (miRNAs) of lncRNAs and the target mRNAs of miRNAs were predicted by a bioinformatics analysis. Functional studies performed using the CCK-8 assay, EdU incorporation assay, apoptosis detection, and senescence-associated β-galactosidase (SA-β-Gal) staining were conducted using GC-1 spg cells.

Results

Totals of 2,652 lncRNAs and 2,625 mRNAs were found to be differentially expressed in the testicular tissue of NOA patients when compared with patients in a control group. Dynamin 3 opposite strand (DNM3OS) was a provider of pe-miR-214-5p that positively regulates miR-214-5p expression in GC-1 spg cells. The E2 factor (E2F) family of transcription factor 2 (E2F2) was initially predicted and subsequently verified to be a downstream gene of miR-214-5p. E2F2 expression was upregulated after DNM3OS knockdown in ADR-treated GC-1 spg cells. Moreover, knockdown of either DNM3OS or miR-214-5p significantly alleviated ADR-induced decreases in cellular activity and proliferation, as well as increases in apoptosis and senescence of mouse spermatogonial GC-1 spg cells.

Conclusions

DNM3OS was found to regulate the apoptosis and senescence of spermatogonia by providing miR-214-5p and decreasing E2F2 expression, suggesting it as a novel target for gene therapy of male infertility.

Pervasive role of the long noncoding RNA DNM3OS in development and diseases

Thousands of unique noncoding RNAs (ncRNAs) are expressed in human cells, some are tissue or cell type specific whereas others are considered as house-keeping molecules. Studies over the last decade have modified our perception of ncRNAs from transcriptional noise to functional regulatory transcripts that influence a variety of molecular processes such as chromatin remodeling, transcription, post-transcriptional modifications, or signal transduction. Consequently, aberrant expression of many ncRNAs plays a causative role in the initiation and progression of various diseases. Since the identification of its developmental role, the long ncRNA DNM3OS (Dynamin 3 Opposite Strand) has attracted attention of researchers in distinct fields including oncology, fibroproliferative diseases, or bone disorders. Mechanistic studies have in particular revealed the multifaceted nature of DNM3OS and its important pathogenic role in several human disorders. In this review, we summarize the current knowledge of DNM3OS functions in diseases, with an emphasis on its potential as a novel therapeutic target. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA in Disease and Development > RNA in Development.

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.

Engineering of MSC-Derived Exosomes: A Promising Cell-Free Therapy for Osteoarthritis

Osteoarthritis (OA) is characterized by progressive cartilage degeneration with increasing prevalence and unsatisfactory treatment efficacy. Exosomes derived from mesenchymal stem cells play an important role in alleviating OA by promoting cartilage regeneration, inhibiting synovial inflammation and mediating subchondral bone remodeling without the risk of immune rejection and tumorigenesis. However, low yield, weak activity, inefficient targeting ability and unpredictable side effects of natural exosomes have limited their clinical application. At present, various approaches have been applied in exosome engineering to regulate their production and function, such as pretreatment of parental cells, drug loading, genetic engineering and surface modification. Biomaterials have also been proved to facilitate efficient delivery of exosomes and enhance treatment effectiveness. Here, we summarize the current understanding of the biogenesis, isolation and characterization of natural exosomes, and focus on the large-scale production and preparation of engineered exosomes, as well as their therapeutic potential in OA, thus providing novel insights into exploring advanced MSC-derived exosome-based cell-free therapy for the treatment of 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.

LncRNA MAFG-AS1 promotes the malignant phenotype of ovarian cancer by upregulating NFKB1-dependent IGF1

Long non-coding RNAs (lncRNAs) were recently recognized to vitally function in a variety of cancer cellular events, including epithelial-mesenchymal transition (EMT), invasion, and migration, particularly in ovarian cancer (OC). Herein, we sought to investigate the potential role of MAFG-AS1 in the malignant behaviors of OC cells. The binding affinity between MAFG-AS1, miR-339-5p, NFKB1 or IGF1 was characterized so as to identify the underlying mechanism of corresponding their interactions. We conducted MAFG-AS1 overexpression or knockdown along with NFKB1 and IGF1 silencing to examine their effects on the EMT, migration, and invasion of OC cells. Tumors were xenografted in nude mice to validate the in vitro findings. Our data showed significantly high expression pattern of MAFG-AS1 in the OC tissues and cells. Further mechanistic investigations revealed that MAFG-AS1 upregulated the IGF1 expression pattern through recruitment of NFKB1, whereas MAFG-AS1 upregulated the NFKB1 expression pattern through binding to miR-339-5p. Thus, MAFG-AS1 overexpression accelerated the EMT, invasion, and migration of OC cells, which could be annulled by silencing of IGF1 or NFKB1. Besides, our in vitro findings were successfully recapitulated in the xenograft mice. These results determined that MAFG-AS1 stimulated the OC malignant progression by upregulating the NFKB1-mediated IGF1 via miR-339-5p, thus highlighting a novel potential therapeutic target against OC.

Comparison of lncRNA Expression in the Uterus between Periods of Embryo Implantation and Labor in Mice

Simple Summary

Progesterone has been proven to play an important role in female mammals during pregnancy. In this study, the uteri of pregnant mice were collected to compare mRNA and lncRNA expression between periods of embryo implantation and labor. The results show that 19 known differentially expressed lncRNAs and 31 novel differentially lncRNAs were commonly expressed between the two stages, indicating that these lncRNAs’ function is related to progesterone.

Abstract

Uterine function during pregnancy is regulated mainly by progesterone (P4) and estrogen (E2). Serum P4 levels are known to fluctuate significantly over the course of pregnancy, especially during embryo implantation and labor. In this study, pregnant mice at E0.5, E4.5, E15.5, and E18.5 (n = 3/E) were used for an RNA-Seq-based analysis of mRNA and lncRNA expression. In this analysis, 1971 differentially expressed (DE) mRNAs, 493 known DE lncRNAs, and 1041 novel DE lncRNAs were found between E0.5 and E4.5 at the embryo implantation stage, while 1149 DE mRNAs, 192 known DE lncRNAs, and 218 novel DE lncRNAs were found between E15.5 and E18.5 at the labor stage. The expression level of lncRNA-MMP11 was significantly downregulated by P4 treatment on MSM cells, while lncRNA-ANKRD37 was significantly upregulated. Notably, 117 DE mRNAs, 19 known DE lncRNAs, and 31 novel DE lncRNAs were commonly expressed between the two stages, indicating that these mRNAs and lncRNAs may be directly or indirectly regulated by P4.

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.

LncRNA SNHG5 promotes chondrocyte proliferation and inhibits apoptosis in osteoarthritis by regulating miR-10a-5p/H3F3B axis

BACKGROUND

Osteoarthritis (OA) is a common degenerative joint disease in the elderly. Increasing evidence suggested that long non-coding RNAs (lncRNAs) played vital roles in OA progression. This study aimed to explore the role and mechanism of lncRNA small nucleolar RNA host gene 5 (SNHG5) in OA development.

METHODS

Chondrocytes were stimulated with interleukin-1β (IL-1β) in vitro. The levels of SNHG5, miR-10a-5p, and H3 histone family 3B (H3F3B) were measured by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Cell proliferation was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and colony formation assay. Cell apoptosis was tested by flow cytometry. The levels of apoptosis-related and cartilage-related markers were detected by western blot. The interaction among SNHG5, miR-10a-5p, and H3F3B was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay.

RESULTS

SNHG5 and H3F3B were downregulated, while miR-10a-5p was upregulated in OA cartilage tissues. Knockdown of SNHG5 enhanced IL-1β-induced apoptosis in chondrocytes. Rescue experiments verified that SNHG5 hindered apoptosis in IL-1β-stimulated chondrocytes by sponging miR-10a-5p. Moreover, H3F3B was a target of miR-10a-5p, and miR-10a-5p promoted IL-1β-induced chondrocyte apoptosis by regulating H3F3B. In addition, SNHG5 regulated H3F3B expression via sponging miR-10a-5p in IL-1β-treated chondrocytes.

CONCLUSION

SNHG5 suppressed chondrocytes apoptosis in OA by regulating the miR-10a-5p/H3F3B axis, which provided a promising biomarker for OA treatment.

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.

Integrated analysis of long non-coding RNAs and mRNAs associated with malignant transformation of gastrointestinal stromal tumors

Malignant transformation of gastrointestinal stromal tumors (GISTs) is correlated with poor prognosis; however, the underlying biological mechanism is not well understood. In the present study, low-risk (LR) GISTs, GISTs categorized as high-risk based on tumor size (HBS), and on mitotic rate (HBM) were collected for RNA sequencing. Candidate hub lncRNAs were selected by Oncomine analysis. Expression of a selected hub lncRNA, DNM3OS, and its correlation with patients’ prognosis were analyzed using FISH staining, followed with the determination of function and underlying mechanism. Our results revealed a series of key pathways and hub lncRNAs involved in the malignant transformation of GISTs. Oncomine analysis revealed a tight association between clinical signatures and DNM3OS and suggested that DNM3OS is a hub lncRNA that is involved in the Hippo signaling pathway. In addition, DNM3OS was upregulated in HBS, HBM, and HBS/M GIST and correlated with worse prognosis in patients with GISTs. In addition, DNM3OS promoted GIST cell proliferation and mitosis by regulating the expression of GLUT4 and CD36. Collectively, these results improve our understanding of the malignant transformation of GISTs and unveil a series of hub lncRNAs in GISTs.

Long non-coding RNA KCNQ1OT1 promotes cell viability and migration as well as inhibiting degradation of CHON-001 cells by regulating miR-126-5p/TRPS1 axis

BACKGROUND

Osteoarthritis (OA) is defined as a degenerative disease. Pivotal roles of long non-coding RNA (lncRNAs) in OA are widely elucidated. Herein, we intend to explore the function and molecular mechanism of lncRNA KCNQ1OT1 in CHON-001 cells.

METHODS

Relative expression of KCNQ1OT1, miR-126-5p and TRPS1 was determined by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability was examined by MTT assay. The migratory ability of chondrocytes was assessed by transwell assay. Western blot was used to determine relative protein expression of collagen II, MMP13 and TRPS1. Dual-luciferase reporter (DLR) assay was applied to test the target of lncRNA KCNQ1OT1 or miR-126-5p.

RESULTS

Relative expression of KCNQ1OT1 and TRPS1 was reduced, whereas miR-126-5p was augmented in cartilage tissues of post-traumatic OA patients compared to those of subjects without post-traumatic OA. Increased KCNQ1OT1 or decreased miR-126-5p enhanced cell viability and migration, and repressed extracellular matrix (ECM) degradation in CHON-001 cells. MiR-126-5p was the downstream target of KCNQ1OT1, and it could directly target TRPS1. There was an inverse correlation between KCNQ1OT1 and miR-126-5p or between miR-126-5p and TRPS1. Meantime, there was a positive correlation between KCNQ1OT1 and TRPS1. The promoting impacts of KCNQ1OT1 on cell viability and migration as well as the suppressive impact of KCNQ1OT1 on ECM degradation were partially abolished by miR-126-5p overexpression or TRPS1 knockdown in CHON-001 cells.

CONCLUSIONS

Overexpression of KCNQ1OT1 attenuates the development of OA by sponging miR-126-5p to target TRPS1. Our findings may provide a possible therapeutic strategy for human OA in clinic.

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.

Up-regulation of long non-coding RNA CYTOR induced by icariin promotes the viability and inhibits the apoptosis of chondrocytes

Background

Icariin (ICAR) is the main effective component extracted from epimedium, and is reported to have the potential to treat osteoarthritis (OA). However, its pharmacological function on chondrocytes has not been fully clarified.

Methods

Different doses of ICAR were used to treat chondrocyte cell lines, including CHON-001 and ATDC5. Then the expressions of different lncRNAs were measured by qRT-PCR. Interleukin-1β (IL-1β) was used to simulate the inflammatory response environment of chondrocytes. Overexpression plasmids and short hairpin RNAs of lncRNA CYTOR were used to construct gain-of-function and loss of function models. CCK-8 was conducted to determine the cell viability. Flow cytometry was used to detect the apoptosis of chondrocytes. Enzyme-linked immunosorbent assay (ELISA) was adopted to measure the contents of inflammatory factors (IL-6, IL-8, TNF-α) in the supernatant of the chondrocytes.

Results

Compared with other lncRNAs, CYTOR was changed most significantly in both CHON-001 and ATDC5 cells after treatment with ICAR. ICAR promotes the viability and inhibits the apoptosis of CHON-001 and ATDC5 cells induced by IL-1β, accompanied with reduced levels of inflammatory factors. Overexpression of CYTOR facilitated the viability of chondrocytes, while repressed their apoptosis and inflammatory response. What’s more, knockdown of CYTOR reversed the protective effects of ICAR on chondrocytes.

Conclusion

CYTOR was a pivotal lncRNA involved in the protective function of ICAR on chondrocytes.

A novel tumor suppressor ASMTL-AS1 regulates the miR-1228-3p/SOX17/β-catenin axis in triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is a special type of breast cancer that lacks effective therapeutic targets. There is a significant need to clarify its pathogenesis, so as to bring new targeted approaches for TNBC management. Here, we identified a long-non coding RNA (lncRNA) ASMTL-AS1 that linked to TNBC development and progression.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot assays were used to test gene and protein levels, respectively. The regulatory axis of miR-1228-3p/SOX17/β-catenin was determined by luciferase reporter and RNA pull-down assays. In vivo assay was conducted by using the nude mice model via subcutaneous transplantation of tumor cells.

RESULTS

ASMTL-AS1 was significantly downregulated in TNBC tissues compared to normal tissues, which was closely associated with aggressive clinical features and unfavorable prognosis. Lentivirus-mediated ASMTL-AS1 overexpression evidently reduced the ability of TNBC cell colony formation, activity and invasion by more than 2.5 times. RNA pull-down and luciferase reporter assays revealed that miR-1228-3p directly bound to ASMTL-AS1, ASMTL-AS1 increased SOX17 expression via sponging and repressing miR-1228-3p. Subsequently, the upregulated SOX17 trans-suppressed β-catenin expression, resulting in the inactivation of carcinogenic Wnt/β-catenin signaling, thereby restraining TNBC cell growth and dissemination. Importantly, the xenograft tumor model showed that the ASMTL-AS1 overexpression significantly retarded tumor growth, and negatively regulated Wnt/β-catenin pathway.

CONCLUSIONS

Our data characterize a novel tumor suppressor in TNBC, restoration of ASMTL-AS1 may be a candidate therapeutic intervention for TNBC patients.

Long non-coding RNA MCM3AP-AS1 protects chondrocytes ATDC5 and CHON-001 from IL-1β-induced inflammation via regulating miR-138-5p/SIRT1

Osteoarthritis (OA) is a chronic inflammatory joint disease. Increased apoptosis of chondrocytes contributes to cartilage degradation in OA pathogenesis. The function of lncRNA MCM3AP-AS1 in regulating the viability of chondrocytes still awaits further elaboration. In this work, MCM3AP-AS1, miR-138-5p and SIRT1 mRNA expression levels in OA and normal cartilage tissues were detected by qRT-PCR. Besides, chondrocyte cell lines, CHON-001 and ATDC5 induced by interleukin-1β (IL-1β) were used to initiate the inflammatory response environment of OA. CCK-8 assay was used to examine the cell multiplication; meanwhile, transwell assay was utilized to detect migration. Western blot was adopted to determine SIRT1 expression in chondrocyte. Enzyme-linked immunosorbent assay (ELISA) was performed to evaluate inflammatory factor levels. In addition, the binding sites between MCM3AP-AS1 and miR-138-5p, miR-138-5p and 3'UTR of SIRT1 were validated by dual-luciferase reporter assay, RIP assay or RNA pull-down assay. It was found that MCM3AP-AS1 was declined in OA cartilage tissues, positively interrelated with SIRT1 expression while negatively correlated with miR-138-5p. MCM3AP-AS1 up-regulation enhanced the viability and migration of CHON-001 and ATDC5 cells while restraining the apoptosis and inflammatory response. Additionally, miR-138-5p overexpression counteracted the effects on chondrocytes caused by MCM3AP-AS1 overexpression. MCM3AP-AS1 could adsorb miR-138-5p, and SIRT1 was verified as a target of miR-138-5p, and SIRT1 could be up-regulated by overexpression of MCM3AP-AS1 indirectly. In conclusion, MCM3AP-AS1 has the potential to be the 'ceRNA' to regulate miR-138-5p and SIRT1 in chondrocytes, and to participate in the pathogenesis of OA.

Long non-coding RNA GAS5 suppresses rheumatoid arthritis progression via miR-128-3p/HDAC4 axis

Rheumatoid arthritis (RA) is a highly relevant public health problem. RA fibroblast-like synoviocytes (RAFLSs) play an important role in RA progression. Long non-coding RNA growth arrest-specific transcript 5 (GAS5) could improve RA by inducing RAFLSs apoptosis. However, the mechanism of GAS5 in RA remains unclear. RT-qPCR detected the expressions of GAS5, microRNA-128-3p (miR-128-3p), and histone deacetylase 4 (HDAC4) in RA synovial tissues and RAFLSs. Proliferation, apoptosis, migration, and invasion were measured by Cell Counting Kit-8 assay (CCK-8), flow cytometry, and transwell assays, severally. The protein levels of B-cell lymphoma-2 (Bcl-2), C-caspase 3, Bcl-2 related X protein (Bax), Tumor Necrosis factor-α (TNF-α), Interleukin 6 (IL-6), Interleukin 17 (IL-17), HDAC4, phosphorylation-protein kinase B (p-AKT), AKT, a phosphorylation-mechanistic target of rapamycin (p-mTOR), and mTOR were assessed by western blot assay. The interaction between miR-128-3p and GAS5 or HDAC4 was predicted by ENCORI or TargetScan Human and verified by the dual-luciferase reporter, RNA Immunoprecipitation (RIP), and RNA pull-down assays. GAS5 and HDAC4 were downregulated, and miR-128-3p was upregulated in RA synovial tissues and RAFLSs. Function analysis indicated that GAS5 curbed proliferation, migration, invasion, inflammation, and facilitated apoptosis of RAFLSs. Rescue assay confirmed that miR-128-3p overexpression or HDAC4 knockdown weakened the inhibitory effect of GAS5 or anti-miR-128-3p on RA development. GAS5 acted as a miR-128-3p sponge to upregulate HDAC4 expression. Besides, GAS5/miR-128-3p/HDAC4 axis regulated RA progression partially through the AKT/mTOR pathway. Our studies disclosed that GAS5 restrained inflammation in synovial tissue partly through regulating HDAC4 via miR-128-3p, suggesting a potential lncRNA-targeted therapy for RA treatment.

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.

Delineation of the 1q24.3 microdeletion syndrome provides further evidence for the potential role of non-coding RNAs in regulating the skeletal phenotype

Microdeletions within 1q24 have been associated with growth deficiency, varying intellectual disability, and skeletal abnormalities. The candidate locus responsible for the various phenotypic features of this syndrome has previously been predicted to lie in the area of 1q24.3, but molecular evidence of the causative gene remains elusive. Here, we report two additional patients carrying the smallest reported 1q24 deletion to date. Patient 1 exhibited intrauterine growth retardation, shortening of the long bones, frontal bossing, microstomia, micrognathia, and a language acquisition delay. Her mother, Patient 2, displayed a broad forehead and nasal bridge, thick supraorbital ridges, and toe brachydactyly, along with learning disability and language acquisition delay. The microdeletion encompasses a 94 Kb region containing exon 14 and portions of the surrounding introns of the gene encoding dynamin 3 (DNM3), resulting in an in-frame loss of 38 amino acids. This microdeletion site also contains a long non-coding RNA (DNM3OS) and three microRNAs (miR-214, miR-199A2, and miR-3120). Following culture of patient-derived and control fibroblasts, molecular analyses were performed to determine expression levels of genes affected by the heterozygous deletion. Results show decreased expression of DNM3OS and miR-214-3p in patient fibroblasts cultured in an osteogenic induction medium. Overall, our data provide further evidence to support a functional role for non-coding RNAs in regulating the skeletal phenotype, and the potential of a functionally-impaired DNM3 protein causing the non-skeletal disease pathogenesis.

lncRNA SNHG16 promotes the occurrence of osteoarthritis by sponging miR‑373‑3p

Osteoarthritis (OA) is a common age‑related joint disorder, for which no effective disease‑modifying drugs are currently available. Long non‑coding RNAs (lncRNAs) are involved in the occurrence of OA. lncRNA small nucleolar RNA host gene 16 (SNHG16) has been reported to regulate inflammation; however, the exact biological function of SNHG16 in OA and its underlying mechanism of action remain unclear. In this study, gene and protein expression levels were detected using reverse transcription‑quantitative PCR and western blotting, respectively. Cell apoptosis was analyzed using flow cytometry and ELISA was performed to detect TNF‑α levels. The interactions between lncRNA SNHG16 and microRNA (miR)‑373‑3p were examined using the dual‑luciferase reporter assay. lncRNA SNHG16 was upregulated in OA tissue compared with normal joint tissue. The expression levels of collagen II were significantly reduced in OA tissue compared with normal tissue. Similarly, aggrecan expression levels were significantly reduced in IL‑1β‑treated CHON‑001 cells compared with the controls. In addition, the protein expression levels of MMP13 were significantly increased in OA tissues and IL‑1β‑treated CHON‑001 cells compared with the controls. SNHG16 knockdown significantly increased the expression levels of aggrecan, and decreased the expression levels of MMP13, cleaved caspase‑3 and p21 in IL‑1β‑treated CHON‑001 cells. In addition, IL‑1β induced CHON‑001 cell apoptosis, while SNHG16 knockdown decreased IL‑1β‑induced apoptosis. Furthermore, the luciferase activity assay suggested that SNHG16 negatively regulated miR‑373‑3p in OA. Finally, the results suggested that the proinflammatory effect of IL‑1β on CHON‑001 cells was significantly reduced by SNHG16 knockdown. In conclusion, lncRNA SNHG16 knockdown significantly limited the progression of OA by sponging miR‑373‑3p in vitro, which suggested that SNHG16 may serve as a potential therapeutic target for OA.

Antagonism between splicing and microprocessor complex dictates the serum-induced processing of lnc-MIRHG for efficient cell cycle reentry

Cellular quiescence and cell cycle reentry regulate vital biological processes such as cellular development and tissue homeostasis and are controlled by precise regulation of gene expression. The roles of long noncoding RNAs (lncRNAs) during these processes remain to be elucidated. By performing genome-wide transcriptome analyses, we identify differential expression of several hundreds of lncRNAs, including a significant number of the less-characterized class of microRNA-host-gene (MIRHG) lncRNAs or lnc-MIRHGs, during cellular quiescence and cell cycle reentry in human diploid fibroblasts. We observe that MIR222HG lncRNA displays serum-stimulated RNA processing due to enhanced splicing of the host nascent pri-MIR222HG transcript. The pre-mRNA splicing factor SRSF1 negatively regulates the microprocessor-catalyzed cleavage of pri-miR-222, thereby increasing the cellular pool of the mature MIR222HG Association of SRSF1 to pri-MIR222HG, including to a mini-exon, which partially overlaps with the primary miR-222 precursor, promotes serum-stimulated splicing over microRNA processing of MIR222HG Further, we observe that the increased levels of spliced MIR222HG in serum-stimulated cells promote the cell cycle reentry post quiescence in a microRNA-independent manner. MIR222HG interacts with DNM3OS, another lncRNA whose expression is elevated upon serum-stimulation, and promotes cell cycle reentry. The double-stranded RNA binding protein ILF3/2 complex facilitates MIR222HG:DNM3OS RNP complex assembly, thereby promoting DNM3OS RNA stability. Our study identifies a novel mechanism whereby competition between the splicing and microprocessor machinery modulates the serum-induced RNA processing of MIR222HG, which dictates cell cycle reentry.

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.

Long non-coding RNA XIST contributes to osteoarthritis progression via miR-149-5p/DNMT3A axis

Long non-coding RNAs (lncRNAs) are largely involved in the development of osteoarthritis (OA), a chronic and degenerative joint disease. The objective of this paper is to research the functional role and molecular mechanism of lncRNA X inactive specific transcript (XIST) in OA. The levels of XIST, microRNA-149-5p (miR-149-5p), and DNA methyltransferase 3A (DNMT3A) were measured. Cell viability and apoptosis rate were determined. Associated protein levels were examined through Western blot. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were implemented for confirming the target relation. And the role of XIST on OA in vivo was investigated by a rat model. XIST was expressed at a high level in OA cartilage tissues and IL-1β-treated chondrocytes. XIST knockdown promoted cell viability but restrained cell apoptosis and extracellular matrix (ECM) protein degradation in IL-1β-treated chondrocytes. XIST directly targeted miR-149-5p and miR-149-5p down-regulation restored si-XIST-mediated pro-proliferative and anti-apoptotic or ECM degradative effects. DNMT3A was a target gene of miR-149-5p and DNMT3A overexpression ameliorated miR-149-5p-induced promotion of cell viability but repression of apoptosis and ECM degradation. Knockdown of XIST reduced DNMT3A level by motivating miR-149-5p expression. The inhibitory influence of XIST down-regulation on OA evolvement was also achieved by miR-149-5p/DNMT3A axis in vivo. In a word, knockdown of XIST can repress the development of OA by miR-149-5p/DNMT3A axis. This study discovers the XIST/miR-149-5p/DNMT3A axis in regulating OA evolution, which is beneficial for understanding the molecular pathomechanism and can lay a good foundation for targeted therapy of OA treatment.