LncRNA MALAT1 sponges miR-30 to promote osteoblast differentiation of adipose-derived mesenchymal stem cells by promotion of Runx2 expression

Long noncoding RNA MALAT1 mediates fibrous topography-driven pathologic calcification through trans-differentiation of myoblasts

Prosthesis-induced pathological calcification is a significant challenge in biomaterial applications and is often associated with various reconstructive medical procedures. It is uncertain whether the fibrous extracellular matrix (ECM) adjacent to biomaterials directly triggers osteogenic trans-differentiation in nearby cells. To investigate this possibility, we engineered a heterogeneous polystyrene fibrous matrix (PSF) designed to mimic the ECM. Our findings revealed that the myoblasts grown on this PSF acquired osteogenic properties, resulting in mineralization both in vitro and in vivo. Transcriptomic analyses indicated a notable upregulation in the expression of the long noncoding RNA metastsis-associated lung adenocarcinoma transcript 1 (Malat1) in the C2C12 myoblasts cultured on PSF. Intriguingly, silencing Malat1 curtailed the PSF-induced mineralization and downregulated the expression of bone morphogenetic proteins (Bmps) and osteogenic markers. Further, we found that PSF prompted the activation of Yap1 signaling and epigenetic modifications in the Malat1 promoter, crucial for the expression of Malat1. These results indicate that the fibrous matrix adjacent to biomaterials can instigate Malat1 upregulation, subsequently driving osteogenic trans-differentiation in myoblasts and ectopic calcification through its transcriptional regulation of osteogenic genes, including Bmps. Our findings point to a novel therapeutic avenue for mitigating prosthesis-induced pathological calcification, heralding new possibilities in the field of biomaterial-based therapies.

Long non-coding RNAs in bone formation: Key regulators and therapeutic prospects

Recent scientific investigations have revealed the intricate mechanisms underlying bone formation, emphasizing the essential role of long non-coding RNAs (lncRNAs) as critical regulators. This process, essential for skeletal strength and functionality, involves the transformation of mesenchymal stem cells into osteoblasts and subsequent deposition of bone matrix. lncRNAs, including HOX transcript antisense RNA (HOTAIR), metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), differentiation antagonizing non-coding RNA (DANCR), and maternally expressed gene 3 (MEG3), have emerged as prominent players in this regulatory network. HOTAIR modulates osteoblast differentiation by interacting with chromatin-modifying enzymes, while MALAT1 regulates osteogenic differentiation through microRNA interactions. DANCR collaborates with Runx2 to fine-tune osteoblast differentiation, and MEG3 orchestrates multiple signaling pathways crucial for bone formation. Moreover, other lncRNAs such as H19, lncRNA for enhancing osteogenesis 3, rhabdomyosarcoma 2-associated transcript, urothelial cancer associated 1, taurine up-regulated gene 1, and nuclear enriched abundant transcript 1 contribute to the complex regulatory network governing osteoblast activities. Understanding the precise roles of these lncRNAs offers promising avenues for developing innovative therapeutic strategies targeting bone-related disorders like osteoporosis. Overall, this review summarizes the pivotal role of lncRNAs in bone formation, highlighting their potential as targets for future research endeavors aimed at advancing therapeutic interventions in bone diseases.

RUNX2 regulation in osteoblast differentiation: A possible therapeutic function of the lncRNA and miRNA-mediated network

Osteogenic differentiation is a crucial process in the formation of the skeleton and the remodeling of bones. It relies on a complex system of signaling pathways and transcription factors, including Runt-related transcription factor 2 (RUNX2). Non-coding RNAs (ncRNAs) control the bone-specific transcription factor RUNX2 through post-transcriptional mechanisms to regulate osteogenic differentiation. The most research has focused on microRNAs (miRNAs) and long ncRNAs (lncRNAs) in studying how they regulate RUNX2 for osteogenesis in both normal and pathological situations. This article provides a concise overview of the recent advancements in understanding the critical roles of lncRNA/miRNA/axes in controlling the expression of RUNX2 during bone formation. The possible application of miRNAs and lncRNAs as therapeutic agents for the treatment of disorders involving the bones and bones itself is also covered.

Epimedium-Curculigo herb pair enhances bone repair with infected bone defects and regulates osteoblasts through LncRNA MALAT1/miR-34a-5p/SMAD2 axis

Infected bone defects (IBDs) are the common condition in the clinical practice of orthopaedics. Although surgery and anti-infective medicine are the firstly chosen treatments, in many cases, patients experience a prolonged bone union process after anti-infective treatment. Epimedium-Curculigo herb pair (ECP) has been proved to be effective for bone repair. However, the mechanisms of ECP in IBDs are insufficiency. In this study, Effect of ECP in IBDs was verified by micro-CT and histological examination. Qualitative and quantitative analysis of the main components in ECP containing medicated serum (ECP-CS) were performed. The network pharmacological approaches were then applied to predict potential pathways for ECP associated with bone repair. In addition, the mechanism of ECP regulating LncRNA MALAT1/miRNA-34a-5p/SMAD2 signalling axis was evaluated by molecular biology experiments. In vivo experiments indicated that ECP could significantly promote bone repair. The results of the chemical components analysis and the pathway identification revealed that TGF-β signalling pathway was related to ECP. The results of in vitro experiments indicated that ECP-CS could reverse the damage caused by LPS through inhibiting the expressions of LncRNA MALAT1 and SMAD2, and improving the expressions of miR-34a-5p, ALP, RUNX2 and Collagen type І in osteoblasts significantly. This research showed that ECP could regulate the TGF-β/SMADs signalling pathway to promote bone repair. Meanwhile, ECP could alleviate LPS-induced bone loss by modulating the signalling axis of LncRNA MALAT1/miRNA-34a-5p/ SMAD2 in IBDs.

Identification and bioinformatics analysis of lncRNAs in serum of patients with ankylosing spondylitis

OBJECTIVES

The aim of this study was to explore the long non-coding RNA (lncRNA) expression profiles in serum of patients with ankylosing spondylitis (AS). The role of these lncRNAs in this complex autoimmune situation needs to be evaluated.

METHODS

We used high-throughput whole-transcriptome sequencing to generate sequencing data from three patients with AS and three normal controls (NC). Then, we performed bioinformatics analyses to identify the functional and biological processes associated with differentially expressed lncRNAs (DElncRNAs). We confirmed the validity of our RNA-seq data by assessing the expression of eight lncRNAs via quantitative reverse transcription polymerase chain reaction (qRT-PCR) in 20 AS and 20 NC samples. We measured the correlation between the expression levels of lncRNAs and patient clinical index values using the Spearman correlation test.

RESULTS

We identified 72 significantly upregulated and 73 significantly downregulated lncRNAs in AS patients compared to NC. qRT-PCR was performed to validate the expression of selected DElncRNAs; the results demonstrated that the expression levels of MALAT1:24, NBR2:9, lnc-DLK1-35:13, lnc-LARP1-1:1, lnc-AIPL1-1:7, and lnc-SLC12A7-1:16 were consistent with the sequencing analysis results. Enrichment analysis showed that DElncRNAs mainly participated in the immune and inflammatory responses pathways, such as regulation of protein ubiquitination, major histocompatibility complex class I-mediated antigen processing and presentation, MAPkinase activation, and interleukin-17 signaling pathways. In addition, a competing endogenous RNA network was constructed to determine the interaction among the lncRNAs, microRNAs, and mRNAs based on the confirmed lncRNAs (MALAT1:24 and NBR2:9). We further found the expression of MALAT1:24 and NBR2:9 to be positively correlated with disease severity.

CONCLUSION

Taken together, our study presents a comprehensive overview of lncRNAs in the serum of AS patients, thereby contributing novel perspectives on the underlying pathogenic mechanisms of this condition. In addition, our study predicted MALAT1 has the potential to be deeply involved in the pathogenesis of AS.

Long noncoding RNA Malat1 protects against osteoporosis and bone metastasis

MALAT1, one of the few highly conserved nuclear long noncoding RNAs (lncRNAs), is abundantly expressed in normal tissues. Previously, targeted inactivation and genetic rescue experiments identified MALAT1 as a suppressor of breast cancer lung metastasis. On the other hand, Malat1-knockout mice are viable and develop normally. On a quest to discover the fundamental roles of MALAT1 in physiological and pathological processes, we find that this lncRNA is downregulated during osteoclastogenesis in humans and mice. Remarkably, Malat1 deficiency in mice promotes osteoporosis and bone metastasis of melanoma and mammary tumor cells, which can be rescued by genetic add-back of Malat1. Mechanistically, Malat1 binds to Tead3 protein, a macrophage-osteoclast-specific Tead family member, blocking Tead3 from binding and activating Nfatc1, a master regulator of osteoclastogenesis, which results in the inhibition of Nfatc1-mediated gene transcription and osteoclast differentiation. Notably, single-cell transcriptome analysis of clinical bone samples reveals that reduced MALAT1 expression in pre-osteoclasts and osteoclasts is associated with osteoporosis and metastatic bone lesions. Altogether, these findings identify Malat1 as a lncRNA that protects against osteoporosis and bone metastasis.

Epigenetic Regulation of Autophagy in Bone Metabolism

The skeletal system is crucial for supporting bodily functions, protecting vital organs, facilitating hematopoiesis, and storing essential minerals. Skeletal homeostasis, which includes aspects such as bone density, structural integrity, and regenerative processes, is essential for normal skeletal function. Autophagy, an intricate intracellular mechanism for degrading and recycling cellular components, plays a multifaceted role in bone metabolism. It involves sequestering cellular waste, damaged proteins, and organelles within autophagosomes, which are then degraded and recycled. Autophagy's impact on bone health varies depending on factors such as regulation, cell type, environmental cues, and physiological context. Despite being traditionally considered a cytoplasmic process, autophagy is subject to transcriptional and epigenetic regulation within the nucleus. However, the precise influence of epigenetic regulation, including DNA methylation, histone modifications, and non-coding RNA expression, on cellular fate remains incompletely understood. The interplay between autophagy and epigenetic modifications adds complexity to bone cell regulation. This article provides an in-depth exploration of the intricate interplay between these two regulatory paradigms, with a focus on the epigenetic control of autophagy in bone metabolism. Such an understanding enhances our knowledge of bone metabolism-related disorders and offers insights for the development of targeted therapeutic strategies.

MALAT1/miR-7-5p/TCF4 Axis Regulating Menstrual Blood Mesenchymal Stem Cells Improve Thin Endometrium Fertility by the Wnt Signaling Pathway

Thin endometrium (TE) is a significant factor contributing to fertility challenges, and addressing this condition remains a central challenge in reproductive medicine. Menstrual blood-derived mesenchymal stem cells (MenSCs) play a crucial role in tissue repair and regeneration, including that of TE. The Wnt signaling pathway, which is highly conserved and prevalent in eukaryotes, is essential for cell proliferation, tissue development, and reproductive functions. MALAT1 is implicated in various transcriptional and molecular functions, including cell proliferation and metastasis. However, the combined effects of the Wnt signaling pathway and the long non-coding RNA (lncRNA) MALAT1 on the regulation of MenSCs' regenerative capabilities in tissue engineering have not yet been explored. To elucidate the regulatory mechanism of MALAT1 in TE, we analyzed its expression levels in normal endometrium and TE tissues, finding that low expression of MALAT1 was associated with poor clinical prognosis. In addition, we conducted both in vitro and in vivo functional assays to examine the role of the MALAT1/miR-7-5p/TCF4 axis in cell proliferation and migration. Techniques such as dual-luciferase reporter assay, fluorescent in situ hybridization, and immunoblot experiments were utilized to clarify the molecular mechanism. To corroborate these findings, we established a TE model and conducted pregnancy experiments, demonstrating a strong association between MALAT1 expression and endometrial fertility. In conclusion, our comprehensive study provides strong evidence supporting that lncRNA MALAT1 modulates TCF4 expression in the Wnt signaling pathway through interaction with miR-7-5p, thus enhancing MenSCs-mediated improvement of TE and improving fertility.

The ATF4-regulated LncRNA MALAT1 promotes odontoblastic differentiation of human dental pulp stem cells via histone demethylase JMJD3: An in vitro study

AIM

This study aimed to investigate the upstream regulators and specific mechanisms of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in the odontoblastic differentiation of human dental pulp stem cells (hDPSCs).

METHODOLOGY

Human dental pulp stem cells were isolated and cultured, followed by conducting loss- or gain-of-function experiments on ATF4 and loss experiments on MALAT1 to elucidate their respective biological functions in odontoblastic differentiation. Chromatin immunoprecipitation assays and RNA immunoprecipitation were performed to uncover the interaction between ATF4-MALAT1 and MALAT1-JMJD3, respectively. The odontoblastic differentiation was estimated by the mRNA and protein of DSPP and DMP1, as well as alkaline phosphatase staining.

RESULTS

Expression of MALAT1 was upregulated in the hDPSCs cultured in an odontoblastic medium, and MALAT1 downregulation suppressed the odontoblastic differentiation of the hDPSCs. Subsequent experiments confirmed that ATF4 promoted odontoblastic differentiation and induced MALAT1 expression by binding to the MALAT1 promoter region. Further experiments revealed that nuclear MALAT1 interacted with JMJD3. MALAT1 knockdown decreased the JMJD3 protein level and demethylase activity, and it enhanced H3K27me3 occupancy of the promoter region of DSPP and DMP1, resulting in the inhibition of DSPP and DMP1 transcription. Importantly, JMJD3 overexpression significantly attenuated the inhibition of odontoblastic differentiation induced by MALAT1 knockdown.

CONCLUSIONS

ATF4-regulated MALAT1 plays a positive regulatory role in odontoblastic differentiation of hDPSCs through JMJD3-mediated H3K27me3 modifications of the DSPP and DMP1 promoters.

Long non-coding RNA (lncRNA) MALAT1 in regulating osteogenic and adipogenic differentiation using a double-stranded gapmer locked nucleic acid nanobiosensor

Long non-coding RNAs (lncRNA) are non-protein coding RNA molecules that are longer than 200 nucleotides. The lncRNA molecule plays diverse roles in gene regulation, chromatin remodeling, and cellular processes, influencing various biological pathways. However, probing the complex dynamics of lncRNA in live cells is a challenging task. In this study, a double-stranded gapmer locked nucleic acid (ds-GapM-LNA) nanobiosensor is designed for visualizing the abundance and expression of lncRNA in live human bone-marrow-derived mesenchymal stem cells (hMSCs). The sensitivity, specificity, and stability were characterized. The results showed that this ds-GapM-LNA nanobiosensor has very good sensitivity, specificity, and stability, which allows for dissecting the regulatory roles of cellular processes during dynamic physiological events. By incorporating this nanobiosensor in living hMSC imaging, we elucidated lncRNA MALAT1 expression dynamics during osteogenic and adipogenic differentiation. The data reveal that lncRNA MALAT1 expression is correlated with distinct sub-stages of osteogenic and adipogenic differentiation.

Long non-coding RNA MALAT1 sponges miR-30c to promote the calcification of human vascular smooth muscle cells by regulating Runx2

OBJECTIVES

Recent evidence suggested that long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) play critical roles in the pathogenesis of vascular calcification (VC). In this study, we tried to explore the expression and role of a lncRNA, i.e., metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), and a miRNA, i.e., miR-30c, in VC.

METHODS

In vitro VC model was induced in human vascular smooth muscle cells (VSMCs) after 10 days culture in calcifying medium containing 2 mM Na₂HPO₄. Alizarin red S staining, calcium assay and western blot analysis of runt-related transcription factor 2 (Runx2) and alpha smooth muscle actin (α-SMA) were performed to evaluate VC. Knockdown of MALAT1 and up-regulation of MALAT1, miR-30c and Runx2 was performed to determine the impact of these molecules on VSMCs calcification. Dual-luciferase report assay was performed to confirm the relationship between MALAT1 and miR-30c or miR-30c and Runx2. In addition, quantitative reverse transcription PCR and western blot were used to determine gene and protein expression.

RESULTS

MALAT1 was increased, while miR-30c was decreased in calcified VSMCs. Knockdown of MALAT1 suppressed VSMCs calcification; on the contrary, up-regulation of MALAT1 promoted VSMCs calcification. The effect of MALAT1 over-expression on VSMCs calcification was reversed by upregulation of miR-30c, which was reversed again by upregulation of Runx2. Dual-luciferase report assay confirmed that there is a direct interaction between MALAT1 and miR-30c, and Runx2 is a direct target of miR-30c.

CONCLUSION

MALAT1 over-expression promoted VSMCs calcification, which was at least partially through regulating the miR-30c/Runx2 axis.

Differentiation of osteoblasts: the links between essential transcription factors

Osteoblasts, cells derived from mesenchymal stem cells (MSCs) in the bone marrow, are cells responsible for bone formation and remodeling. The differentiation of osteoblasts from MSCs is triggered by the expression of specific genes, which are subsequently controlled by pro-osteogenic pathways. Mature osteoblasts then differentiate into osteocytes and are embedded in the bone matrix. Dysregulation of osteoblast function can cause inadequate bone formation, which leads to the development of bone disease. Various key molecules are involved in the regulation of osteoblastogenesis, which are transcription factors. Previous studies have heavily examined the role of factors that control gene expression during osteoblastogenesis, both in vitro and in vivo. However, the systematic relationship of these transcription factors remains unknown. The involvement of ncRNAs in this mechanism, particularly miRNAs, lncRNAs, and circRNAs, has been shown to influence transcriptional factor activity in the regulation of osteoblast differentiation. Here, we discuss nine essential transcription factors involved in osteoblast differentiation, including Runx2, Osx, Dlx5, β-catenin, ATF4, Ihh, Satb2, and Shn3. In addition, we summarize the role of ncRNAs and their relationship to these essential transcription factors in order to improve our understanding of the transcriptional regulation of osteoblast differentiation. Adequate exploration and understanding of the molecular mechanisms of osteoblastogenesis can be a critical strategy in the development of therapies for bone-related diseases.Communicated by Ramaswamy H. Sarma.

A potential therapeutic drug for osteoporosis: prospect for osteogenic LncRNAs

Long non-coding RNAs (LncRNAs) play essential roles in multiple physiological processes including bone formation. Investigators have revealed that LncRNAs regulated bone formation through various signaling pathways and micro RNAs (miRNAs). However, several problems exist in current research studies on osteogenic LncRNAs, including sophisticated techniques, high cost for in vivo experiment, as well as low homology of LncRNAs between animal model and human, which hindered translational medicine research. Moreover, compared with gene editing, LncRNAs would only lead to inhibition of target genes rather than completely knocking them out. As the studies on osteogenic LncRNA gradually proceed, some of these problems have turned osteogenic LncRNA research studies into slump. This review described some new techniques and innovative ideas to address these problems. Although investigations on osteogenic LncRNAs still have obtacles to overcome, LncRNA will work as a promising therapeutic drug for osteoporosis in the near future.

LncRNA MALAT1 improves cerebral ischemia-reperfusion injury and cognitive dysfunction by regulating miR-142-3p/SIRT1 axis

PURPOSE

To investigate the regulation and related mechanisms of MALAT1 in cerebral ischemia- reperfusion (CI/R) injury.

MATERIALS AND METHODS

72 mice were divided into sham group (n=24), MCAO group (n=24), MCAO+pcDNA-NC group (n=12) and MCAO+MALAT1 group (n=12). At 12 h, 24 h and 48 h after reperfusion, 6 mice were randomly selected from the sham group and the MCAO group to detect the expression of MALAT1, miR-142-3p and SIRT1 in brain tissue. All mice were scored for neurobehavioral after 48 h of reperfusion. After the completion of the scoring, 6 mice were randomly selected from each group and brain tissue was obtained for TTC analysis. The remaining mice of each group were kept on the Morris water maze test after 3 days of feeding. TTC staining and cerebral infarct volume determination. The infarct size of each brain slice was calculated using Image J image analysis software. OGD/R model PC12 cells were prepared according to simulating CI/R injury in vitro. MALAT1 was cloned into the pcDNA3.1 to construct a MALAT1 overexpression vector with the empty vector NC as a control. Plasmid or oligonuceotides were transfected into PC12 cells. The content of TNF-α, IL-1β, IL-6, the content of reactive oxygen species (ROS), malondialdehyde (MDA) in brain tissue was detected. The activity of superoxide dismutase (SOD), catalase (CAT) activity was measured.

RESULTS

MALAT1 was down-regulated in a time-dependent manner in CI/R-damaged mouse cerebral cortex and OGD/R-induced PC12 cells, accompanied by an increase in the expression of miR-142-3p and a decrease in sirtuin 1 (SIRT1) expression. Overexpression of MALAT1 inhibited OGD/R-induced cell necrosis and apoptosis and promoted cell proliferation. Overexpression of MALAT1 reduced the levels of TNF-α, IL-6, IL-1β, ROS and MDA and increased the activities of SOD and CAT in OGD/R-injured PC12 cells. MALAT1 negatively regulated the expression of miR-142-3p, and SIRT1 was a target gene of miR-142-3p. The expression of SIRT1 induced by MALAT1 overexpression was obviously abolished by the introduction of miR-142-3p mimic. MALAT1 overexpression can exert its role by regulating the miR-142-3p/SIRT1 axis. Besides, overexpression of MALAT1 improved cerebral infarction, neurological impairment and cognitive dysfunction in CI/R mice.

CONCLUSION

MALAT1 mediates SIRT1 expression by acting as a ceRNA of miR-142-3p to improve CI/R injury.

Abbreviations: CAT: catalase; CI/R: cerebral ischemia-reperfusion; IL-1β: interleukin-1β; IL-6: interleukin-6; lncRNA: long-chain non-coding RNA; MALAT1: metastasis-associated lung adenocarcinoma transcript1; MCAO: middle cerebral artery occlusion; MDA: malondialdehyde; OGD/R: oxygen-glucose deprivation and reoxygenation; ROS: reactive oxygen species; SIRT1: sirtuin 1; SOD: superoxide dismutase; TNF-α: tumour necrosis factor-alpha.

Effect of LncRNA-MALAT1 on mineralization of dental pulp cells in a high-glucose microenvironment

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) belongs to the long non-coding RNA (LncRNA) family. LncRNA-MALAT1 is expressed in a variety of tissues and is involved in a variety of diseases and biological processes. Although LncRNA-MALAT1 is upregulated in a high-glucose microenvironment and may participate in odontogenic differentiation, the underlying mechanism is not yet well elucidated. Here, we show that MALAT1 was mainly expressed in the cytoplasm of dental pulp cells (DPCs) in situ hybridization. In addition, high levels of mineralization-related factors, namely, tumor growth factors β 1 and 2 (TGFβ-1 and TGFβ-2), bone morphogenetic proteins 2 and 4 (BMP2 and BMP4), bone morphogenetic protein receptor 1 (BMPR1), SMAD family member 2 (SMAD2), runt-related transcription factor 2 (RUNX2), Msh homeobox 2 (MSX2), transcription factor SP7 (SP7), alkaline phosphatase (ALP), dentin matrix acidic phosphoprotein 1 (DMP1), and dentin sialophosphoprotein (DSPP), were expressed, and MALAT1 was significantly overexpressed in DPCs 7 and 14 days after mineralization induction in a high-glucose microenvironment, but only TGFβ-1, BMP2, MSX2, SP7, ALP, and DSPP were significantly downregulated in DPCs after MALAT1 inhibition. MALAT1 may participate in the mineralization process of DPCs by regulating multiple factors (TGFβ-1, BMP2, MSX2, SP7, ALP, and DSPP).

Long Noncoding RNA Metastasis-Associated Lung Adenocarcinoma Transcript 1 Promotes the Osteoblast Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells by Targeting the microRNA-96/Osterix Axis

OBJECTIVES

To investigate whether and how the long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) sponges microRNA-96 (miR-96) to achieve the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs).

METHODS

Protein levels were detected by Western blot. Mineralized bone matrix formation was studied by alizarin red staining. Metastasis-associated lung adenocarcinoma transcript 1, miR-96, and osteogenesis-related Messenger RNA expression was assessed by Quantitative Real-time Polymerase Chain Reaction (qRT-PCR). The interactions between miR-96 and osterix (Osx), MALAT1, and miR-96 were determined by luciferase reporter assay.

RESULTS

The expression of MALAT1 was upregulated whereas that of miR-96 was downregulated in osteogenic hBMSCs. In addition, the expression of MALAT1 significantly decreased whereas that of miR-96 increased in the hBMSCs of osteoporosis (OP) patients. qRT-PCR and alizarin red staining assays showed that MALAT1 silencing or miR-96 overexpression inhibits hBMSC osteogenic differentiation and vice versa. overexpression of miR-96 reversed the promotive effect of MALAT1 on the osteogenic differentiation of hBMSCs. Dual luciferase report assay verified that miR-96 is a regulatory target of MALAT1 and that Osx is a gene target of miR-96.

CONCLUSIONS

Taken together, the results demonstrate that MALAT1 promotes the osteogenic differentiation of hBMSCs by regulating the miR-96/Osx axis. Our study provides novel mechanistic insights into the critical role of lncRNA MALAT1 as a microRNA sponge in OP patients and sheds new light on lncRNA-directed diagnostics and therapeutics in OP.

Adipose mesenchymal stem cell sheets-derived extracellular vesicles-microRNA-10b promote skin wound healing by elevating expression of CDK6

Application of adipose-derived mesenchymal stromal cells (AMSCs)-derived extracellular vesicles (EVs) in skin wound healing has been documented. In this study, we investigated the therapeutic potential of AMSCs-derived EVs in skin wound healing through delivery of microRNA-10b (miR-10b). HaCaT cells were treated with H₂O₂ to establish the skin wound cell models. Next, the binding affinity between miR-194, PEA15, and CDK6 was identified. Additionally, EVs were isolated from the culture medium of AMSC sheets, followed by incubation with H₂O₂-treated HaCaT cells to detect cell proliferation, migration, and apoptosis using gain- or loss-of-function experiments. Lastly, the mice skin wound models were also established to assess skin wound healing ability. miR-10b was down-regulated in the skin trauma models and enriched in the EVs of AMSC sheets. Moreover, miR-10b derived from EVs targeted PEA15 to promote CDK6 expression, thereby stimulating the proliferation and migration of H₂O₂-damaged HaCaT cells but inhibiting apoptosis. In vivo experiments further ascertained the therapeutic functionality of AMSC sheets-derived EVs-miR-10b. In summary, AMSC sheets-derived EVs carrying miR-10b promoted CDK6 expression to intensify skin wound healing by regulating PEA15.

lncRNA MALAT1 mediates osteogenic differentiation of bone mesenchymal stem cells by sponging miR-129-5p

Background

Bone mesenchymal stem cells (BMSCs) have good osteogenic differentiation potential and have become ideal seed cells in bone tissue engineering. However, the osteogenic differentiation ability of BMSCs gradually weakens with age, and the regulatory mechanism is unclear.

Method

We conducted a bioinformatics analysis, dual-luciferase reporter (DLR) experiment, and RNA binding protein immunoprecipitation (RIP) to explore the hub genes that may affect BMSC functions.

Results

The expression level of long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (Malat1) was significantly higher in the BMSCs from elderly than younger mice, while miR-129-5p showed the opposite trend. The results of alkaline phosphatase staining, quantitative reverse transcription PCR and western blot experiments indicated that inhibiting the expression of Malat1 inhibits the osteogenic differentiation of BMSCs. This effect can be reversed by reducing the expression of miR-129-5p. Additionally, DLR and RIP experiments confirmed that Malat1 acts as a sponge for miR-129-5p.

Conclusion

Overall, our study findings indicated that lncRNA Malat1 may play a critical role in maintaining the osteoblast differentiation potential of BMSCs by sponging miR-129-5p.

Long non-coding RNA Linc01133 promotes osteogenic differentiation of human periodontal ligament stem cells via microRNA-30c / bone gamma-carboxyglutamate protein axis

Periodontitis is a chronic inflammation caused by the deposition of dental plaque on the tooth surface. Human periodontal ligament stem cells (hPDLSCs) have the potential of osteogenic differentiation. Long non-coding RNAs (lncRNAs) are collectively involved in periodontitis. This study was designed to explore the roles of Linc01133 in osteogenic differentiation of hPDLSCs. hPDLSCs obtained from the periodontal ligament (PDL) of patients with periodontitis were used to collect Linc01133, microRNA-30c (miR-30c), and bone gamma-carboxyglutamate protein (BGLAP) expression data, and their expression changes were traced during osteogenic differentiation of hPDLSCs. Quantitative reverse-transcription polymerase chain reaction as well as western blotting were used to analyze the levels of RNAs and proteins. Dual-luciferase reporter and RNA pull-down assays demonstrated the relationship between Linc01133, miR-30c, and BGLAP. Furthermore, alkaline phosphatase (ALP) staining and alizarin red staining were applied to evaluate the degree of osteogenic differentiation. Linc01133 was downregulated in the PDL of patients with periodontitis. Upregulated Linc01133 promoted osteogenic differentiation of hPDLSCs. Linc01133 could inhibit miR-30c expression by sponging miR-30c. miR-30c suppressed osteogenic differentiation. Additionally, miR-30c targeted BGLAP. Knockdown of BGLAP abrogated the effects of decreased miR-30c on osteogenic differentiation of hPDLSCs. Linc01133 acted as a ceRNA to regulate osteogenic differentiation of hPDLSCs via the miR-30c/BGLAP axis. Therefore, Linc01133 may participate in the progress of periodontitis.

Long Noncoding RNA IGFBP7-AS1 Promotes Odontogenesis of Stem Cells from Human Exfoliated Deciduous Teeth via the p38 MAPK Pathway

Stem cells from human exfoliated deciduous teeth (SHED) are attractive seed cells for dental tissue engineering. Epigenetics refers to heritable changes in gene expression patterns that do not alter DNA sequences. Long noncoding RNAs (lncRNAs) are one of the main methods of epigenetic regulation and participate in cell differentiation; however, little is known regarding the role of lncRNAs during SHED odontogenic differentiation. In this study, RNA sequencing (RNA-seq) was used to obtain the expression profile of lncRNAs and mRNAs during the odontogenic differentiation of SHED. The effect of IGFBP7-AS1 on odontogenic differentiation of SHED was assessed by alkaline phosphatase (ALP) staining, alizarin red S (ARS) staining, quantitative reverse transcription PCR (qRT-PCR), Western blot, and in vivo. The level of p38 and p-p38 protein expression was examined by Western blot, and the result was verified by adding the p38 inhibitor, SB203580. The expression profiles of lncRNAs and mRNAs were identified by RNA-seq analysis, which help us to further understand the mechanism in odontogenesis epigenetically. IGFBP7-AS1 expression was increased during odontogenic differentiation on days 7 and 14. The ALP staining, ARS staining, and expression of odontogenic markers were upregulated by overexpressing IGFBP7-AS1 in vitro, whereas the expression of osteogenesis markers was not significantly changed on mRNA level. The effect of IGFBP7-AS1 was also verified in vivo. IGFBP7-AS1 could further positively regulate odontogenic differentiation through the p38 MAPK pathway. This may provide novel targets for dental tissue engineering.

Long noncoding RNA Lnc-DIF inhibits bone formation by sequestering miR-489-3p

Osteoporosis has become a high incident bone disease along with the aging of human population. Long noncoding RNAs (LncRNAs) play an important role in osteoporosis incidence. In this study, we screened out an LncRNA negatively correlated with osteoblast differentiation, which was therefore named Lnc-DIF (differentiation inhibiting factor). Functional analysis proved that Lnc-DIF inhibited bone formation. A special structure containing multiple 53 nucleotide repeats was found in the trailing end of Lnc-DIF. Our study suggested that this repeat sequence could sequester multiple miR-489-3p and inhibit bone formation through miR-489-3p/SMAD2 axis. Moreover, siRNA of Lnc-DIF would rescue bone formation in both aging and ovariectomized osteoporosis mice. This study revealed a kind of LncRNA that could function as a sponge and regulate multiple miRNAs. RNA therapy techniques that target these LncRNAs could manipulate its downstream miRNA-target pathway with significantly higher efficiency and specificity. This provided potential therapeutic insight for RNA-based therapy for osteoporosis.

•

Identified LncRNA Lnc-DIF that inhibited bone formation

•

Lnc-DIF sequestered multiple miR-489-3p by the repeat sequences on its trailing end

•

Lnc-DIF repeat sequence inhibited bone formation via miR-489-3p/SMAD2 axis

•

Lnc-DIF siRNA showed strong capability on rescuing osteoporosis

The lncRNAs/miR-30e/CHI3L1 Axis Is Dysregulated in Systemic Sclerosis

Systemic sclerosis (SSc) is an autoimmune disease with completely undefined etiology and treatment difficulties. The expression of both protein coding and non-coding RNAs is dysregulated during disease development. We aimed to examine a possible regulatory axis implemented in the control of chitinase-3 like protein 1 (CHI3L1) or YKL-40, an inflammation-associated glycoprotein, shown to be elevated in SSc. A panel of seven miRNAs and three lncRNAs potentially involved in the control of CHI3L1 were selected on the basis of in silico analysis. TagMan assay was used to evaluate the expression levels of miRNAs and RT-qPCR for lncRNAs in white blood cells (WBCs) and plasma from SSc patients and healthy controls. Among the eight screened miRNAs, miR-30e-5p (p = 0.04) and miR-30a-5p (p = 0.01) were significantly downregulated in WBCs and plasma of SSc patients, respectively. On the contrary, the expression of the metastasis associated lung adenocarcinoma transcript 1 (MALAT1) (p = 0.044) and the Nuclear enriched abundant transcript 1 (NEAT1) (p = 0.008) in WBCs was upregulated compared to the controls. Increased levels of MALAT1 and NEAT1 could be associated with the downregulation of miR-30e-5p and miR-30a-5p expression in WBCs and plasma. We present novel data on the involvement of a possible regulatory axis lncRNAs/miR-30e/CHI3L1 in SSc and hypothesize that MALAT1 and NEAT1 could act as miR-30e-5p and miR-30a-5p decoys. This may be a reason for the increased serum levels of CHI3L1 in SSc patients.

Long Noncoding RNA GAS5: A New Factor Involved in Bone Diseases

Long noncoding RNAs (lncRNAs), as an important type of RNA encoded in the human transcriptome, have shown to regulate different genomic processes in human cells, altering cell type and function. These factors are associated with carcinogenesis, cancer metastasis, bone diseases, and immune system diseases, among other pathologies. Although many lncRNAs are involved in various diseases, the molecular mechanisms through which lncRNAs contribute to regulation of disease are still unclear. The lncRNA growth arrest-specific 5 (GAS5) is a key player that we initially found to be associated with regulating cell growth, differentiation, and development. Further work has shown that GAS5 is involved in the occurrence and prognosis of bone diseases, such as osteoporosis, osteosarcoma, and postosteoporotic fracture. In this review, we discuss recent progress on the roles of GAS5 in bone diseases to establish novel targets for the treatment of bone diseases.

The management of bone defect using long non-coding RNA as a potential biomarker for regulating the osteogenic differentiation process

Tissue engineered bone brings hope to the treatment of bone defects, and the osteogenic differentiation of stem cells is the key link. Inducing osteogenic differentiation of stem cells may be a potential approach to promote bone regeneration. In recent years, lncRNA has been studied in the field increasingly, which is believed can regulate cell cycle, proliferation, metastasis, differentiation and immunity, participating in a variety of physiology and pathology processes. At present, it has been confirmed that certain lncRNAs regulate the osteogenesis of stem cells and take part in mediating signaling pathways including Wnt/β-catenin, MAPK, TGF-β/BMP, and Notch pathways. Here, we provided an overview of lncRNA, reviewed its researches in the osteogenic differentiation of stem cells, emphasized the importance of lncRNA in bone regeneration, and focused on the roles of lncRNA in signaling pathways, in order to make adequate preparations for applying lncRNA to bone tissue Engineering, letting it regulate the osteogenic differentiation of stem cells for bone regeneration.

The regulatory activities of MALAT1 in the development of bone and cartilage diseases

Long non-coding RNAs (lncRNAs) have been comprehensively implicated in various cellular functions by mediating transcriptional or post-transcriptional activities. MALAT1 is involved in the differentiation, proliferation, and apoptosis of multiple cell lines, including BMSCs, osteoblasts, osteoclasts, and chondrocytes. Interestingly, MALAT1 may interact with RNAs or proteins, regulating cellular processes. Recently, MALAT1 has been reported to be associated with the development of bone and cartilage diseases by orchestrating the signaling network. The involvement of MALAT1 in the pathological development of bone and cartilage diseases makes it available to be a potential biomarker for clinical diagnosis or prognosis. Although the potential mechanisms of MALAT1 in mediating the cellular processes of bone and cartilage diseases are still needed for further elucidation, MALAT1 shows great promise for drug development.

Super-Enhancer-Associated Long Non-Coding RNA LINC01485 Promotes Osteogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells by Regulating MiR-619-5p/RUNX2 Axis

OBJECTIVE

To investigate the mechanisms of super-enhancer-associated LINC01485/miR-619-5p/RUNX2 signaling axis involvement in osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs).

METHODS

Osteogenic differentiation of hBMSCs was induced in vitro. The expression levels of LINC01485 and miR-619-5p during osteogenesis were measured using quantitative real-time polymerase chain reaction (qRT-PCR). Osteogenic differentiation was examined by qRT-PCR, western blot, alkaline phosphatase (ALP) staining, ALP activity measurement, and Alizarin Red S (ARS) staining assays. Thereafter, the effects of LINC01485 and miR-619-5p on osteogenic differentiation of hBMSCs were evaluated by performing loss- and gain-of-function experiments. Subsequently, a fluorescence in situ hybridization (FISH) assay was employed to determine the cellular localization of LINC01485. Bioinformatics analysis, RNA antisense purification (RAP) assay, and dual-luciferase reporter assays were conducted to analyze the interactions of LINC01485, miR-619-5p, and RUNX2. Rescue experiments were performed to further delineate the role of the competitive endogenous RNA (ceRNA) signaling axis consisting of LINC01485/miR-619-5p/RUNX2 in osteogenic differentiation of hBMSCs.

RESULTS

The expression of LINC01485 was up-regulated during osteogenic differentiation of hBMSCs. The overexpression of LINC01485 promoted osteogenic differentiation of hBMSCs by up-regulating the expression of osteogenesis-related genes [e.g., runt-related transcription factor 2 (RUNX2), osterix (OSX), collagen type 1 alpha 1 (COL1A1), osteocalcin (OCN), and osteopontin (OPN)], and increasing the activity of ALP. ALP staining and ARS staining were also found to be increased upon overexpression of LINC01485. The opposing results were obtained upon LINC01485 interference in hBMSCs. miR-619-5p was found to inhibit osteogenic differentiation. FISH assay displayed that LINC01485 was mainly localized in the cytoplasm. RAP assay results showed that LINC01485 bound to miR-619-5p, and dual-luciferase reporter assay verified that LINC01485 bound to miR-619-5p, while miR-619-5p and RUNX2 bound to each other. Rescue experiments illustrated that LINC01485 could promote osteogenesis by increasing RUNX2 expression by sponging miR-619-5p.

CONCLUSION

LINC01485 could influence RUNX2 expression by acting as a ceRNA of miR-619-5p, thereby promoting osteogenic differentiation of hBMSCs. The LINC01485/miR-619-5p/RUNX2 axis might comprise a novel target in the bone tissue engineering field.

LncRNA MALAT1 promotes osteogenic differentiation of BMSCs and inhibits osteoclastic differentiation of Mø in osteoporosis via the miR-124-3p/IGF2BP1/Wnt/β-catenin axis

Osteoporosis is defined as a skeletal disorder characterized by impairment in bone strength. The potential application of lncRNAs as therapeutic targets for osteoporosis has been unveiled. This study investigated the regulatory mechanism of lncRNA MALAT1 in the differentiation of bone marrow stem cells (BMSCs) and macrophages (Mø) in osteoporosis. MALAT1 expression in peripheral blood of elderly osteoporosis patients and healthy volunteers was detected. BMSCs and mononuclear Mø were isolated and cultured. Osteogenic differentiation of BMSCs and osteoclastic differentiation of Mø were induced. BMSCs and Mø were transfected with si-MALAT1, miR-124-3p mimics, miR-124-3p inhibitor, or pcDNA IGF2BP1, followed by detection of cell differentiation. The target microRNAs (miRs) and downstream genes and signaling pathways of MALAT1 were examined. The ovariectomy-induced mouse model of osteoporosis was established, and the mice were injected with pcDNA-MALAT1. MALAT1 was downregulated in osteoporosis patients, increased in BMSCs after osteogenic differentiation, and diminished in Mø after osteoclastic differentiation. Downregulation of MALAT1 repressed osteogenic differentiation of BMSCs and facilitated osteoclastic differentiation of Mø. MALAT1 upregulated IGF2BP1 expression by competitively binding to miR-124-3p. miR-124-3p silencing reversed the effect of si-MALAT1 on BMSCs and Mø differentiation, and IGF2BP1 upregulation averted the effect of overexpressed-miR-124-3p by activating the Wnt/β-catenin pathway. Upregulation of MALAT1 activated the Wnt/β-catenin pathway and attenuated bone injury in mice. In conclusion, lncRNA MALAT1 promoted the osteogenic differentiation of BMSCs and inhibited osteoclastic differentiation of Mø in osteoporosis via the miR-124-3p/IGF2BP1/Wnt/β-catenin axis. This article is protected by copyright. All rights reserved.

The Role of Long Non-Coding RNAs and Circular RNAs in Bone Regeneration: Modulating MiRNAs Function

Although bone is a self-healing organ and is able to repair and restore most fractures, large bone fractures, about 10%, are not repairable. Bone grafting, as a gold standard, and bone tissue engineering using biomaterials, growth factors, and stem cells have been developed to restore large bone defects. Since bone regeneration is a complex and multiple-step process and the majority of the human genome, about 98%, is composed of the non-protein-coding regions, non-coding RNAs (ncRNAs) play essential roles in bone regeneration. Recent studies demonstrated that long ncRNAs (lncRNAs) and circular RNAs (circRNAs), as members of ncRNAs, are widely involved in bone regeneration by interaction with microRNAs (miRNAs) and constructing a lncRNA or circRNA/miRNA/mRNA regulatory network. The constructed network regulates the differentiation of stem cells into osteoblasts and their commitment to osteogenesis. This review will present the structure and biogenesis of lncRNAs and circRNAs, the mechanism of bone repair, and the bone tissue engineering in bone defects. Finally, we will discuss the role of lncRNAs and circRNAs in osteogenesis and bone fracture healing through constructing various lncRNA or circRNA/miRNA/mRNA networks and the involved pathways. This article is protected by copyright. All rights reserved.

High Expression MicroRNA-206 Inhibits the Growth of Tumor Cells in Human Malignant Fibrous Histiocytoma

Background: Malignant fibrous histiocytoma (MFH) is a common type of soft tissue sarcoma and a serious threat to human health. MFH often relapses locally after the curettage is related to the residual cancer stem cells (CSCs). Currently, the dysregulation of microRNA (miRNA) has been found to be closely related to the recurrence of CSCs. However, whether dysregulations of miRNAs exist in MFH, CSCs remained unknown.

Methods: In this study, miRNAs in MFH CSCs and MFH common cells were examined by gene probe. Then, target genes and their functions involved in the signal pathway were predicted by the relevant database. Finally, the miRNAs’ target regulatory network was constructed. Furthermore, the miRNAs and target genes were identified by quantitative polymerase chain reaction, whereas miRNA analogs and antagonists were transfected in tumor cells to investigate cell proliferation ability further.

Results: Results showed that a total of 47 miRNAs were found, including 16 that were upregulated and 31 that were downregulated. The screened differential miRNA showed a different expression in the cell resistant strains compared with the control group. Quantitative polymerase chain reaction analysis confirmed that the relative abundance of seven miRNAs and four target genes varied significantly. The encouraging issue is that we found Hsa-miR-206 significantly inhibited MFH proliferative activity.

Conclusion: Hsa-miR-206 played a key role in regulating MFH CSC properties that might be a representative marker and target for the diagnosis and treatment of MFH in the future.

Long non-coding RNA MALAT1 enhances angiogenesis during bone regeneration by regulating the miR-494/SP1 axis

Bone regeneration is a coordinated process involving connections between blood vessels and osteocytes. Angiogenesis and osteogenesis are tightly connected throughout the progression of bone regeneration. This study aimed to explore the underlying mechanism of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)-regulated angiogenesis during bone regeneration. Gene and protein expression was detected by quantitative real-time PCR and western blot assay. Vascular endothelial growth factor (VEGFA) secretion was assessed by enzyme-linked immunosorbent assay. To evaluate the effect of osteogenic differentiation, alkaline phosphatase (ALP) and alizarin red staining assays were performed. Proliferation was detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Migration and angiogenesis were measured using Transwell and tube formation assays. A dual luciferase reporter assay was performed to confirm the binding relationship among MALAT1, miR-494, and specificity protein 1 (SP1). Expression levels of MALAT1, SP1, and VEGFA were elevated and miR-494 was suppressed in MC3T3-E1 cells after culture in osteogenic medium. MALAT1 knockdown suppressed the osteogenic differentiation of MC3T3-E1, since ALP activity, mineralized nodules, and expression of the osteodifferentiated markers runt-related transcription factor 2 and osterix were restrained. In addition, MALAT1 silencing inhibited angiogenesis during bone regeneration, as the proliferation, migration, and capillary tube formation of human umbilical vein endothelial cells were blocked. Furthermore, miR-494 was directly targeted by MALAT1 and regulated the SP1/Toll-like receptor 2 (TLR2)/bone morphogenetic protein 2 (BMP2) axis by targeting SP1. Furthermore, miR-494 overexpression inhibited angiogenesis and osteogenic differentiation. Moreover, SP1 overexpression or miR-494 inhibition rescued the regulatory effect of sh-MALAT1 on angiogenesis and osteogenic differentiation. Taken together, these findings indicate that MALAT1 promotes angiogenesis and osteogenic differentiation by targeting miR-494 and activating the SP1/TLR2/BMP2 pathway, suggesting a novel target for bone regeneration therapy by promoting angiogenesis.

piRNA-36741 regulates BMP2-mediated osteoblast differentiation via METTL3 controlled m6A modification

The osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is essential for bone formation, and its imbalance can lead to bone diseases such as osteoporosis. It is reported that PIWI-interacting RNA-36741 (piR-36741) is up-regulated during the osteogenic differentiation, but its role in regulating osteogenic differentiation remains unclear. Here, the primary human BMSCs were used to induce osteogenic differentiation, and the expression of piR-36741 and METTL3 (methyltransferase like 3) was up-regulated during the osteogenic differentiation of BMSCs. Moreover, interference with piR-36741 or METTL3 markedly hindered the osteogenic differentiation of BMSCs, which was manifested by a reduction in osteoblast marker expression (including RUNX2, COL1A1, OPN and OCN), osteogenic phenotype and matrix mineralization. Mechanistically, the piR-36741-PIWIL4 complex directly interacted with METTL3 and prevented METTL3-mediated m6A modification of BMP2 mRNA transcripts, thereby promoting BMP2 expression. And overexpression of BMP2 reversed the inhibitory effect of piR-36741 silence on osteogenic differentiation and the Smad pathway activity. In addition, administration with piR-36741 mimic alleviated ovariectomy-induced osteoporosis in mice. In conclusion, piRNA-36741 overexpression promoted osteogenic differentiation of BMSCs and mitigated ovariectomy-induced osteoporosis through METTL3-mediated m6A methylation of BMP2 transcripts.

Betulinic acid promotes the osteogenic differentiation of human periodontal ligament stem cells by upregulating EGR1

Periodontitis is one of the most common chronic inflammations of the oral cavity, which eventually leads to tooth loss. Betulinic acid (BetA) is an organic acid that has anti-inflammatory effects and is derived from fruits and plants, but its effect on the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) is still unclear. This study aimed to explore the effect of BetA on the osteogenic differentiation of hPDLSCs and its mechanism. Our results revealed that BetA not only promoted the viability of hPDLSCs but also induced their osteogenic differentiation in a dose-dependent manner. In addition, RNA sequencing was used to screen the differentially expressed genes (DEGs) after hPDLSCs were treated with BetA, and 127 upregulated and 138 downregulated genes were identified. Gene Ontology enrichment analysis showed that DEGs were mainly involved in the response to lithium ions and the positive regulation of macrophage-derived foam cell differentiation. The Kyoto Encyclopedia of Genes and Genomes analysis results revealed that DEGs were enriched in the nuclear factor-κB and interleukin-17 signaling pathways. More importantly, we confirmed that early growth response gene 1 (EGR1), one of the three DEGs involved in bone formation, significantly promoted the expression of osteogenic markers and the mineralization of hPDLSCs. Knockdown of EGR1 obviously limited the effect of BetA on the osteogenic differentiation of hPDLSCs. In conclusion, BetA promoted the osteogenic differentiation of hPDLSCs through upregulating EGR1, and BetA might be a promising candidate in the clinical application of periodontal tissue regeneration.

NF-κB inducible miR-30b-5p aggravates joint pain and loss of articular cartilage via targeting SIRT1-FoxO3a-mediated NLRP3 inflammasome

MicroRNAs (miRNAs) contribute to osteoarthritis (OA) development. Nevertheless, the function and mechanism of miR-30b-5p in OA are unclear. In the present article, we gauged the miR-30b-5p level in OA patients and analyzed its correlation with OA stages. Then, we conducted in-vivo and in-vitro gain-of-function assays to determine the function of miR-30b-5p, silent information regulator 2 homolog 1 (SIRT1) and Fox. Cell counting Kit-8 (CCK-8) assay, BrdU assay and flow cytometry were utilized to gauge cell viability and apoptosis of human chondrocyte (HC-A). The targeting association between miR-30b-5p and SIRT1 was validated through the dual-luciferase reporter assay and RNA immunoprecipitation (RIP) experiment. The results signified that miR-30b-5p was up-regulated in OA patients, OA rats and interleukin-1β (IL-1β)-induced chondrocytes. The higher miR-30b-5p expression brought about progressive stages of OA patients and enhanced levels of pro-inflammatory mediators in the synovial fluid. Functionally, overexpressing miR-30b-5p hampered cell viability, aggravated chondrocyte apoptosis and NLRP3 inflammasome activation induced by IL-1β, while down-regulating miR-30b-5p exerted the reverse effects. The in-vivo experiment exhibited that down-regulating miR-30b-5p improved joint pain and loss of articular cartilage in the rats with restrained inflammation and NLRP3 inflammasome activation. Mechanistically, miR-30b-5p targeted the 3'-non-translated region (3'UTR) of SIRT1, and miR-30b-5p was inducible with NF-κB phosphorylation enhancement. Overexpressing SIRT1 or inhibiting NF-κB relieved miR-30b-5p-induced apoptosis and NLRP3 inflammasome activation by promoting FoxO3a, while down-regulating SIRT1 or FoxO3a reversed miR-30b-5p-in-induced anti-inflammatory and apoptosis-suppressive effects. Collectively, NF-κB-induced miR-30b-5p modulates chondrocyte apoptosis and OA progression by regulating the SIRT1-FoxO3a-mediated NLRP3 inflammasome.

LINC00370 modulates miR-222-3p-RGS4 axis to protect against osteoporosis progression

BACKGROUND

We aimed to determine the role of the LINC00370/miR-222-3p/RGS4 axis in modulating the process of adipose-derived stem cell (ADSC) osteogenic differentiation.

METHODS

We first evaluated the differential expression of LINC00370, miR-222-3p and RGS4 between normal and osteogenically induced ADSCs. Moreover, we transfected ADSCs with LINC00370 siRNA and an miR-222-3p inhibitor to determine the role of LINC00370 in modulating the process of ADSC osteogenic differentiation. Finally, we analyzed the dual-luciferase reporter gene to identify the relationship between LINC00370 and miR-222-3p. We first created osteoporotic rat models by ovariectomy (OVX) and treated with pcDNA-LINC00370. HE and immunohistochemical staining of OCN were performed to assess the changes in bone microarchitecture.

RESULTS

LINC00370 and RGS4 expression was remarkably upregulated in the osteogenic ADSC group compared with the normal medium group. On the other hand, miR-222-3p expression was remarkably decreased in the osteogenic group compared with the normal medium group. Knockdown of LINC00370 reduced the osteogenic differentiation of ADSCs. Moreover, the inhibitor of miR-222-3p partially reversed the reduction of osteogenic differentiation by LINC00370 knockdown. Knockdown of LINC00370 reduced the expression of p-Akt and p-PI3K. The inhibitor of miR-222-3p partially reversed the reduction of the expression of p-Akt and p-PI3K by LINC00370 knockdown. A dual luciferase reporter assay indicated that LINC00370 can directly bind miR-222-3p. LINC00370 suppressed OP progression in OVX and partially upregulated OCN protein expression.

CONCLUSION

Collectively, the above results confirm that LINC00370 promotes the process of ADSC osteogenic differentiation via the miR-222-3p/RGS4 axis. Moreover, LINC00370 could protect against OVX-induced OP.

The impact of non-coding RNAs on normal stem cells

Self-renewal and differentiation into diverse cells are two main characteristics of stem cells. These cells have important roles in development and homeostasis of different tissues and are supposed to facilitate tissue regeneration. Function of stem cells is regulated by dynamic interactions between external signaling, epigenetic factors, and molecules that regulate expression of genes. Among the highly appreciated regulators of function of stem cells are long non-coding RNAs (lncRNAs) and microRNAs (miRNAs). Impact of miR-342-5p, miR-145, miR-1297, miR-204-5p, miR-132, miR-128-3p, hsa-miR-302, miR-26b-5p and miR-10a are among miRNAs that regulate function of stem cells. Among lncRNAs, AK141205, ANCR, MEG3, Pnky, H19, TINCR, HULC, EPB41L4A-AS1 and SNHG7 have important roles in the regulation of stem cells. In the current paper, we aimed at reviewing the importance of miRNAs and lncRNAs in differentiation of stem cells both in normal and diseased conditions. For this purpose, we searched PubMed/Medline and google scholar databases using "stem cell" AND "lncRNA", or "long non-coding RNA", or "microRNA" or "miRNA".

MALAT1 regulates osteogenic differentiation of human periodontal ligament stem cells through mediating miR-155-5p/ETS1 axis

BACKGROUND

Osteogenic differentiation of human periodontal ligament stem cells is essential to periodontal regeneration treatment for periodontitis. This study investigated the mechanism of lncRNAs-related osteogenic differentiation.

METHODS

Human periodontal ligament stem cells were extracted from human periodontal ligament and identified via flow cytometry. After being induced into osteogenic differentiation for three weeks using osteoblast inducing conditional media, human periodontal ligament stem cells were transfected with siRNA-MALAT1, or miR-155-5p inhibitor. Human periodontal ligament stem cells osteogenesis was observed by alkaline phosphatase staining, followed by alizarin red staining for evaluating mineralized nodes formation. Runt-related gene 2, collagen-1 and osteocalcin expressions were assessed by western blot and qRT-PCR.

RESULTS

MALAT1 expression was assumed a negative correlation with miR-155-5p expression which was dropping over time in differentiating human periodontal ligament stem cells. MALAT1 could bind with miR-155-5p, and E26 transformation specific-1 (ETS1) was the targeted gene of miR-155-5p. Silenced MALAT1 suppressed ALP activity and mineralized nodes formation and inhibited the expressions of runt-related gene 2, collagen-1 and osteocalcin in differentiating human periodontal ligament stem cells, while miR-155-5p inhibitor reversed the effect of si-MALAT1 on differentiation of human periodontal ligament stem cells.

CONCLUSION

MALAT1 modulated differentiation of human periodontal ligament stem cells via regulating miR-155-5p.

The role of long noncoding RNA THAP9-AS1 in the osteogenic differentiation of dental pulp stem cells via the miR-652-3p/VEGFA axis

Dental pulp stem cells (DPSCs) are multipotent and may play crucial roles in dentin-pulp regeneration. Recent studies have revealed that long noncoding RNAs (lncRNAs) are implicated in the osteogenic differentiation of DPSCs. However, the specific role and potential mechanisms of the lncRNA trihydroxyacetophenone domain containing nine antisense RNA 1 (THAP9-AS1) during osteogenic differentiation of DPSCs remain unknown. In the present study, we determined that THAP9-AS1 expression was upregulated during osteogenic differentiation of DPSCs. Moreover, we investigated the biological functions of THAP9-AS1 during osteogenic differentiation of DPSCs by loss-of-function assays. THAP9-AS1 knockdown inhibited osteogenic differentiation of DPSCs by decreasing alkaline phosphatase activity, alkaline phosphatase-positive cell ratio, mineralizing matrix and mRNA, and protein levels of early osteogenic-markers. We also found that THAP9-AS1 interacted with miR-652-3p, whose downstream gene target is vascular endothelial growth factor A (VEGFA). In addition, rescue assays indicated that VEGFA rescued the effects of THAP9-AS1 knockdown during osteogenic differentiation of DPSCs. In summary, we verified that knockdown of THAP9-AS1 inhibits osteogenic differentiation of DPSCs via the miR-652-3p/VEGFA axis. Our findings may be helpful to extend research on the mechanisms underlying osteogenic differentiation of DPSCs.

The role of circRNA derived from RUNX2 in the serum of osteoarthritis and its clinical value

Background

Circular RNA (circRNA) has been shown to affect the pathological process of osteoarthritis (OA) and is expected to become a potential marker for disease diagnosis. This study aimed to investigate the association between circRNA derived from the gene of runt‐related transcription factor 2 (RUNX2) and OA risk.

Methods

The expression profile of RUNX2‐derived circRNAs in serum of OA patients was detected. Then, the cytological localization of screened differential circRNAs was studied. Luciferase (LUC) reporter assay was used to identify the microRNA (miRNA) sponge capacity of the circRNAs. Bioinformatics analysis was used to construct the functional pathway of this circRNA‐miRNAs network. And then, the diagnostic value of RUNX2‐derived circRNAs in OA was evaluated.

Results

RUNX2‐derived hsa_circ_0005526 (circ_RUNX2) is significantly highly expressed in OA serum and mainly located in the cytoplasm within the cartilage cell by sponging multiple miRNAs (miR‐498, miR‐924, miR‐361‐3p, and miR‐665). Bioinformatics analysis showed ECM‐receptor interaction pathway ranked the most significant pathway of circ_RUNX2‐miRNAs regulatory network in KEGG database. The ROC curve showed that there may be good diagnostic value of serum circ_RUNX2 in OA.

Conclusion

RUNX2‐derived circ_RUNX2 may be involved in OA development via ECM‐receptor interaction pathways and may be used as potential clinical indicator of OA.

Long noncoding RNA AC092155 facilitates osteogenic differentiation of adipose-derived stem cells through the miR-143-3p/STMN1 axis

BACKGROUND

Numerous studies have demonstrated that long noncoding RNAs (lncRNAs) induce osteogenesis in adipose-derived stem cells (ADSCs). This study aimed to explore the role of lncRNAs AC092155 in promoting osteogenic differentiation of ADSCs.

METHODS

MicroRNA (miRNA) and lncRNA sequencing were performed in ADSCs that underwent normal or osteogenic induction. Differentially expressed miRNAs and lncRNAs were identified using R software. The relative expression levels of lncRNA AC092155, miR-143-3p, and STMN1 during the process of osteogenic induction were determined by real-time polymerase chain reaction (RT-PCR). ADSCs were then transfected with agomiR-143-3p and pcDNA3.1-sh-lncRNA AC092155. Alkaline phosphatase (ALP) and alizarin red staining (ARS) were used to confirm the regulatory function of the lncRNA AC092155/miR-143-3p/STMN1 axis in osteogenic differentiation of ADSCs.

RESULTS

lncRNA AC092155 was significantly upregulated in ADSCs following induction in the osteogenic medium. lncRNA AC092155 and STMN1 mimics increase the markers of osteogenic differentiation in the early and late phases, which was reflected in increased ALP activity as well as the higher deposition of calcium nodules. An miR-143-3p mimic showed the opposite effect. Luciferase reporter gene analysis demonstrated that lncRNA AC092155 directly targets miR-143-3p. Moreover, the lncRNA AC092155/miR-143-3p/STMN1 regulatory axis was found to activate the Wnt/β-catenin signaling pathway.

CONCLUSIONS

lncRNA AC092155 contributes to the osteogenic differentiation of ADSCs. The lncRNA AC092155/miR-143-3p/STMN1 axis may be a new therapeutic target for bone-related diseases.

The potential role of lncRNAs in osteoporosis

Osteoporosis is a common bone disease characterized by low bone mass and deterioration of bone microstructure, which predisposes to higher risks of bone fragility and bone fracture. Long non-coding RNAs (lncRNAs) are a class of RNAs with a length of > 200 nucleotides without protein-coding function, which control the expression of genes and affect multiple biological processes. Accumulating evidence suggests that lncRNAs are widely involved in the molecular mechanisms of osteoporosis. This review aims to summarize the function and underlying mechanism of lncRNAs involved in the development of osteoporosis, and how it contributes to osteoblast and osteoclast function. This knowledge will shed new light on the modulation and potential treatment of osteoporosis.

The role of microRNAs in the osteogenic and chondrogenic differentiation of mesenchymal stem cells and bone pathologies

Mesenchymal stem cells (MSCs) have been identified in many adult tissues. MSCs can regenerate through cell division or differentiate into adipocytes, osteoblasts and chondrocytes. As a result, MSCs have become an important source of cells in tissue engineering and regenerative medicine for bone tissue and cartilage. Several epigenetic factors are believed to play a role in MSCs differentiation. Among these, microRNA (miRNA) regulation is involved in the fine modulation of gene expression during osteogenic/chondrogenic differentiation. It has been reported that miRNAs are involved in bone homeostasis by modulating osteoblast gene expression. In addition, countless evidence has demonstrated that miRNAs dysregulation is involved in the development of osteoporosis and bone fractures. The deregulation of miRNAs expression has also been associated with several malignancies including bone cancer. In this context, bone-associated circulating miRNAs may be useful biomarkers for determining the predisposition, onset and development of osteoporosis, as well as in clinical applications to improve the diagnosis, follow-up and treatment of cancer and metastases. Overall, this review will provide an overview of how miRNAs activities participate in osteogenic/chondrogenic differentiation, while addressing the role of miRNA regulatory effects on target genes. Finally, the role of miRNAs in pathologies and therapies will be presented.

The Involvement of Long Non-Coding RNAs in Bone

A harmonious balance between osteoblast and osteoclast activity guarantees optimal bone formation and resorption, pathological conditions affecting the bone may arise. In recent years, emerging evidence has shown that epigenetic mechanisms play an important role during osteoblastogenesis and osteoclastogenesis processes, including long non-coding RNAs (lncRNAs). These molecules are a class of ncRNAs with lengths exceeding 200 nucleotides not translated into protein, that have attracted the attention of the scientific community as potential biomarkers to use for the future development of novel diagnostic and therapeutic approaches for several pathologies, including bone diseases. This review aims to provide an overview of the lncRNAs and their possible molecular mechanisms in the osteoblastogenesis and osteoclastogenesis processes. The deregulation of their expression profiles in common diseases associated with an altered bone turnover is also described. In perspective, lncRNAs could be considered potential innovative molecular biomarkers to help with earlier diagnosis of bone metabolism-related disorders and for the development of new therapeutic strategies.

Long Non-coding RNAs and MicroRNAs Interplay in Osteogenic Differentiation of Mesenchymal Stem Cells

Long non-coding RNAs (lncRNAs) have gained great attention as epigenetic regulators of gene expression in many tissues. Increasing evidence indicates that lncRNAs, together with microRNAs (miRNAs), play a pivotal role in osteogenesis. While miRNA action mechanism relies mainly on miRNA-mRNA interaction, resulting in suppressed expression, lncRNAs affect mRNA functionality through different activities, including interaction with miRNAs. Recent advances in RNA sequencing technology have improved knowledge into the molecular pathways regulated by the interaction of lncRNAs and miRNAs. This review reports on the recent knowledge of lncRNAs and miRNAs roles as key regulators of osteogenic differentiation. Specifically, we described herein the recent discoveries on lncRNA-miRNA crosstalk during the osteogenic differentiation of mesenchymal stem cells (MSCs) derived from bone marrow (BM), as well as from different other anatomical regions. The deep understanding of the connection between miRNAs and lncRNAs during the osteogenic differentiation will strongly improve knowledge into the molecular mechanisms of bone growth and development, ultimately leading to discover innovative diagnostic and therapeutic tools for osteogenic disorders and bone diseases.

The Expression and Function of Metastases Associated Lung Adenocarcinoma Transcript-1 Long Non-Coding RNA in Subchondral Bone and Osteoblasts from Patients with Osteoarthritis

Metastasis Associated Lung Adenocarcinoma Transcript-1 (MALAT1) is implicated in regulating the inflammatory response and in the pathology of several chronic inflammatory diseases, including osteoarthritis (OA). The purpose of this study was to examine the relationship between OA subchondral bone expression of MALAT1 with parameters of joint health and biomarkers of joint inflammation, and to determine its functional role in human OA osteoblasts. Subchondral bone and blood were collected from hip and knee OA patients (n = 17) and bone only from neck of femur fracture patients (n = 6) undergoing joint replacement surgery. Cytokines were determined by multiplex assays and ELISA, and gene expression by qPCR. MALAT1 loss of function was performed in OA patient osteoblasts using locked nucleic acids. The osteoblast transcriptome was analysed by RNASeq and pathway analysis. Bone expression of MALAT1 positively correlated to serum DKK1 and galectin-1 concentrations, and in OA patient osteoblasts was induced in response to IL-1β stimulation. Osteoblasts depleted of MALAT1 exhibited differential expression (>1.5 fold change) of 155 genes, including PTGS2. Both basal and IL-1β-mediated PGE2 secretion was greater in MALAT1 depleted osteoblasts. The induction of MALAT1 in human OA osteoblasts upon inflammatory challenge and its modulation of PGE2 production suggests that MALAT1 may play a role in regulating inflammation in OA subchondral bone.

MicroRNAs Possibly Involved in the Development of Bone Metastasis in Clear-Cell Renal Cell Carcinoma

Simple Summary

Bone metastases cause substantial morbidity and implicate worse clinical outcomes for clear-cell renal cell carcinoma patients. MicroRNAs are small RNA molecules that modulate gene translation and are involved in the development of cancer and metastasis. We identified six microRNAs that are potentially specifically involved in metastasis to bone, of which two seem protective and four implicate a higher risk. This aids further understanding of the process of metastasizing to bone. Furthermore, these microRNA hold potential for biomarkers or therapeutic targets.

Abstract

Bone metastasis in clear-cell renal cell carcinoma (ccRCC) leads to substantial morbidity through skeletal related adverse events and implicates worse clinical outcomes. MicroRNAs (miRNA) are small non-protein coding RNA molecules with important regulatory functions in cancer development and metastasis. In this retrospective analysis we present dysregulated miRNA in ccRCC, which are associated with bone metastasis. In particular, miR-23a-3p, miR-27a-3p, miR-20a-5p, and miR-335-3p specifically correlated with the earlier appearance of bone metastasis, compared to metastasis in other organs. In contrast, miR-30b-3p and miR-139-3p were correlated with less occurrence of bone metastasis. These miRNAs are potential biomarkers and attractive targets for miRNA inhibitors or mimics, which could lead to novel therapeutic possibilities for bone targeted treatment in metastatic ccRCC.

ETS Proto-Oncogene 1 Suppresses MicroRNA-128 Transcription to Promote Osteogenic Differentiation Through the HOXA13/β-Catenin Axis

ETS proto-oncogene 1 (ETS1) has been implicated in osteoporosis (OP), but the exact molecular mechanisms are complex. This work focuses on the impact of ETS1 on the osteogenic differentiation and the molecules involved. A mouse pre-osteoblast cell line MC3T3-E1 was used for in vitro experiments. ETS1 was upregulated during the process of osteogenic differentiation of MC3T3-E1 cells. Overexpression of ETS1 promoted expression of osteogenic markers, alkaline phosphate concentration, and calcareous accumulation in cells. ETS1 was found to specifically bind to miR-128 promoter to suppress its transcription, while miR-128 could target homeobox A13 (HOXA13). Therefore, ETS1 suppressed miR-128 transcription to upregulate HOXA13 expression. Overexpression of HOXA13 promoted the osteogenic differentiation ability of cells and increased the protein level of β-catenin. Either overexpression of miR-128 or downregulation of β-catenin by CWP232228, a β-catenin-specific antagonist, blocked the promoting roles of ETS1 in cells. To conclude, this study provided evidence that ETS1 suppresses miR-128 transcription to activate the following HOXA13/β-catenin axis, therefore promoting osteogenic differentiation ability of MC3T3-E1 cells. This finding may offer novel ideas for OP treatment.

MicroRNAs Modulate Signaling Pathways in Osteogenic Differentiation of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have been identified in many adult tissues and they have been closely studied in recent years, especially in view of their potential use for treating diseases and damaged tissues and organs. MSCs are capable of self-replication and differentiation into osteoblasts and are considered an important source of cells in tissue engineering for bone regeneration. Several epigenetic factors are believed to play a role in the osteogenic differentiation of MSCs, including microRNAs (miRNAs). MiRNAs are small, single-stranded, non-coding RNAs of approximately 22 nucleotides that are able to regulate cell proliferation, differentiation and apoptosis by binding the 3' untranslated region (3'-UTR) of target mRNAs, which can be subsequently degraded or translationally silenced. MiRNAs control gene expression in osteogenic differentiation by regulating two crucial signaling cascades in osteogenesis: the transforming growth factor-beta (TGF-β)/bone morphogenic protein (BMP) and the Wingless/Int-1(Wnt)/β-catenin signaling pathways. This review provides an overview of the miRNAs involved in osteogenic differentiation and how these miRNAs could regulate the expression of target genes.

Involvement of the long noncoding RNA H19 in osteogenic differentiation and bone regeneration

Osteogenic differentiation and bone regeneration are complex processes involving multiple genes and multiple steps. In this review, we summarize the effects of the long noncoding RNA (lncRNA) H19 on osteogenic differentiation.

Osteogenic differentiation includes matrix secretion and calcium mineralization as hallmarks of osteoblast differentiation and the absorption of calcium and phosphorus as hallmarks of osteoclast differentiation. Mesenchymal stem cells (MSCs) form osteoprogenitor cells, pre-osteoblasts, mature osteoblasts, and osteocytes through induction and differentiation. lncRNAs regulate the expression of coding genes and play essential roles in osteogenic differentiation and bone regeneration. The lncRNA H19 is known to have vital roles in osteogenic induction.

This review highlights the role of H19 as a novel target for osteogenic differentiation and the promotion of bone regeneration.