MiR-199b-5p inhibits osteogenic differentiation in ligamentum flavum cells by targeting JAG1 and modulating the Notch signalling pathway

Inhibition of miR-199b-5p reduces pathological alterations in osteoarthritis by potentially targeting Fzd6 and Gcnt2

Osteoarthritis (OA) is a degenerative disease with a high prevalence in the elderly population, but our understanding of its mechanisms remains incomplete. Analysis of serum exosomal small RNA sequencing data from clinical patients and gene expression data from OA patient serum and cartilage obtained from the GEO database revealed a common dysregulated miRNA, miR-199b-5p. In vitro cell experiments demonstrated that miR-199b-5p inhibits chondrocyte vitality and promotes extracellular matrix degradation. Conversely, inhibition of miR-199b-5p under inflammatory conditions exhibited protective effects against damage. Local viral injection of miR-199b-5p into mice induced a decrease in pain threshold and OA-like changes. In an OA model, inhibition of miR-199b-5p alleviated the pathological progression of OA. Furthermore, bioinformatics analysis and experimental validation identified Gcnt2 and Fzd6 as potential target genes of MiR-199b-5p. Thus, these results indicated that MiR-199b-5p/Gcnt2 and Fzd6 axis might be a novel therapeutic target for the treatment of OA.

Epigenetic modifications in spinal ligament aging

Spinal stenosis is a common degenerative spine disorder in the aged population and the spinal ligament aging is a main contributor to this chronic disease. However, the underlying mechanisms of spinal ligament aging remain unclear. Epigenetics is the study of heritable and reversible changes in the function of a gene or genome that occur without any alteration in the primary DNA sequence. Epigenetic alterations have been demonstrated to play crucial roles in age-related diseases and conditions, and they are recently studied as biomarkers and therapeutic targets in the field of cancer research. The main epigenetic modifications, including DNA methylation alteration, histone modifications as well as dysregulated noncoding RNA modulation, have all been implicated in spinal ligament aging diseases. DNA methylation modulates the expression of critical genes including WNT5A, GDNF, ACSM5, miR-497 and miR-195 during spinal ligament degeneration. Histone modifications widely affect gene expression and obvious histone modification abnormalities have been found in spinal ligament aging. MicroRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) exert crucial regulating effects on spinal ligament aging conditions via targeting various osteogenic or fibrogenic differentiation related genes. To our knowledge, there is no systematic review yet to summarize the involvement of epigenetic mechanisms of spinal ligament aging in degenerative spinal diseases. In this study, we systematically discussed the different epigenetic modifications and their potential functions in spinal ligament aging process.

The miR-98-3p/JAG1/Notch1 axis mediates the multigenerational inheritance of osteopenia caused by maternal dexamethasone exposure in female rat offspring

As a synthetic glucocorticoid, dexamethasone is widely used to treat potential premature delivery and related diseases. Our previous studies have shown that prenatal dexamethasone exposure (PDE) can cause bone dysplasia and susceptibility to osteoporosis in female rat offspring. However, whether the effect of PDE on bone development can be extended to the third generation (F3 generation) and its multigenerational mechanism of inheritance have not been reported. In this study, we found that PDE delayed fetal bone development and reduced adult bone mass in female rat offspring of the F1 generation, and this effect of low bone mass caused by PDE even continued to the F2 and F3 generations. Furthermore, we found that PDE increases the expression of miR-98-3p but decreases JAG1/Notch1 signaling in the bone tissue of female fetal rats. Moreover, the expression changes of miR-98-3p/JAG1/Notch1 caused by PDE continued from the F1 to F3 adult offspring. Furthermore, the expression levels of miR-98-3p in oocytes of the F1 and F2 generations were increased. We also confirmed that dexamethasone upregulates the expression of miR-98-3p in vitro and shows targeted inhibition of JAG1/Notch1 signaling, leading to poor osteogenic differentiation of bone marrow mesenchymal stem cells. In conclusion, maternal dexamethasone exposure caused low bone mass in female rat offspring with a multigenerational inheritance effect, the mechanism of which is related to the inhibition of JAG1/Notch1 signaling caused by the continuous upregulation of miR-98-3p expression in bone tissues transmitted by F2 and F3 oocytes.

MicroRNA-199b Deregulation Shows Oncogenic Properties and Promising Clinical Value as Circulating Marker in Locally Advanced Rectal Cancer Patients

The identification of robust prognostic markers still represents a need in locally advanced rectal cancer (LARC). MicroRNAs (miRs) have progressively emerged as promising circulating markers, overcoming some limitations that traditional biopsy comprises. Tissue miR-199b deregulation has been reported to predict outcome and response to neoadjuvant chemoradiotherapy (nCRT) in LARC, and was also found to be associated with disease progression in colorectal cancer. However, its biological and clinical relevance remains to be fully clarified. Thus, we observed here that miR-199b regulates cell migration, aggressiveness, and cell growth, and inhibits colonosphere formation and induces caspase-dependent apoptosis. Moreover, miR-199b expression was quantified by real-time PCR in plasma samples from LARC patients and its downregulation was observed in 22.7% of cases. This alteration was found to be associated with higher tumor size (p = 0.002) and pathological stage (p = 0.020) after nCRT. Notably, we observed substantially lower global miR-199b expression associated with patient downstaging (p = 0.009), as well as in non-responders compared to those cases who responded to nCRT in both pre- (p = 0.003) and post-treatment samples (p = 0.038). In concordance, we found that miR-199b served as a predictor marker of response to neoadjuvant therapy in our cohort (p = 0.011). Altogether, our findings here demonstrate the functional relevance of miR-199b in this disease and its potential value as a novel circulating marker in LARC.

MicroRNAs Regulation in Osteogenic Differentiation of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are a kind of pluripotent stem cell with the potential of self-renewal and multidirectional differentiation. They can be obtained from a variety of tissues and can differentiate into a variety of cell types under different induction conditions, including osteoblasts. Because of this osteogenic property, MSCs have attracted much attention in the treatment of bone metabolism-related diseases. MicroRNAs (miRNAs), as an epigenetic factor, are thought to play an important regulatory role in the process of osteogenic differentiation of MSCs. In recent years, increasingly evidence shows that miRNAs imbalance is involved in the regulation of osteoporosis and fracture. In this review, miRNAs involved in osteogenic differentiation and their mechanisms for regulating the expression of target genes are reviewed. In addition, we also discuss the potential clinical applications and possible directions of this field in the future.

Circular RNA Expression Profile in Patients with Lumbar Spinal Stenosis Associated with Hypertrophied Ligamentum Flavum

STUDY DESIGN

Sequencing and experimental analysis of the expression profile of circular RNAs (circRNAs) in hypertrophic ligamentum flavum (LFH).

OBJECTIVES

The aim of this study was to identify differentially expressed circRNAs between LFH and nonhypertrophic ligamentum flavum tissues from lumbar spinal stenosis (LSS) patients.

SUMMARY OF BACKGROUND DATA

Hypertrophy of the ligamentum flavum (LF) can cause LSS. circRNAs are important in various diseases. However, no circRNA expression patterns related to LF hypertrophy have been reported.

METHODS

A total of 33 patients with LSS participated in this study. LF tissue samples were obtained when patients underwent decompressive laminectomy during surgery. The expression profile of circRNAs was analyzed by transcriptome high-throughput sequencing and validated with quantitative real-time polymerase chain reaction (PCR). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed for the differentially expressed circRNA-associated genes and related pathways. The connections between circRNAs and microRNAs were explored using Cytoscape. The role of hsa_circ_0052318 on LF cell fibrosis was assessed by analyzing the expression of collagen I and collagen III.

RESULTS

The results showed that 2439 circRNAs of 4025 were differentially expressed between the LFH and nonhypertrophic ligamentum flavum tissues, including 1276 upregulated and 1163 downregulated circRNAs. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that these differentially expressed circRNAs functioned in biological processes, cellular components, and molecular functions. Autophagy and mammalian target of rapamycin were the top two signaling pathways affected by these circRNAs. Five circRNAs (hsa_circ_0021604, hsa_circ_0025489, hsa_circ_0002599, hsa_circ_0052318, and hsa_circ_0003609) were confirmed by quantitative real-time PCR. The network indicated a strong relationship between circRNAs and miRNAs. Furthermore, hsa_circ_0052318 overexpression decreased mRNA and protein expression of collagen I and III in LF cells from LFH tissues.

CONCLUSION

This study identified circRNA expression profiles characteristic of hypertrophied LF in LSS patients, and demonstrated that hsa_circ_0052318 may play an important role in the pathogenesis of LF hypertrophy.Level of Evidence: N/A.

Integrating Bioinformatic Strategies with Real-World Data to Infer Distinctive Immunocyte Infiltration Landscape and Immunologically Relevant Transcriptome Fingerprints in Ossification of Ligamentum Flavum

Purpose

Ossification of the ligamentum flavum (OLF) is a multifactorial disease characterized by an insidious and debilitating process of abnormal bone formation in ligamentum tissues. However, its definite pathogenesis has not been fully elucidated. Potential links between the immune system and various forms of heterotopic ossification have been discussed for many years, whereas no research investigated the immune effects on the initiation and development of OLF. Therefore, we attempt to shed light on this issue.

Methods

A series of bioinformatic algorithms were integrated to evaluate the immune score and the immunocyte infiltration patterns between OLF and normal samples, screen OLF-related and immune-related differentially expressed genes (OIDEGs), and analyze their biological functions. Correlation analysis inferred OIDEGs-related differentially expressed lncRNAs (OIDELs) and infiltrating immune cells (OIICs) to construct an immunoregulatory network.

Results

Differential immune score and immune cell infiltration were determined between two groups, and 10 OIDEGs with diverse biological function annotations were identified and verified. A lncRNA-gene-immunocyte regulatory network further revealed 10 OIDEGs, 41 OIDELs and 7 OIICs that were highly correlated. Among them, CD1E and STAT3 were predicted as hub genes whether at the expression level or interaction level. cDCs emerged as having the most prominent differences and the highest degree of connectivity. FO393414.3, AC096734.1, LINC01137 and DLX6-AS1 with the greatest number of OIDEGs were thought to be more likely to participate in immunoregulation of OLF.

Conclusion

This is the first research to preliminarily elucidate OLF-related immunocyte infiltration landscape and immune-associated transcriptome signatures based on bioinformatic strategies and real-world data, which may provide compelling insights into the pathogenesis and therapeutic targets of OLF.

Association analysis and functional study of COL6A1 single nucleotide polymorphisms in thoracic ossification of the ligamentum flavum in the Chinese Han population

PURPOSE

Genetic factors play a crucial role in thoracic ossification of the ligamentum flavum (TOLF). This study aimed to better understand the association between single nucleotide polymorphisms (SNP) in functional regions of the collagen VI, alpha 1 gene (COL6A1) and TOLF, and to confirm COL6A1 as a TOLF susceptibility gene.

METHODS

Ten tag SNPs in COL6A1 were genotyped using the SNaPshot assay, and allele and genotype frequencies were compared between TOLF patients and control individuals. The function of SNPs associated with disease was studied. For COL6A1 promoter SNPs, the transcriptional activity of each haplotype was determined by luciferase reporter assays. For COL6A1 exonic SNPs, the effect of nucleotide substitutions on COL6A1 expression was determined by western blotting. COL6A1 mRNA expression in ligamentum flavum tissues from TOLF patients with different genotypes was examined using reverse transcription real-time PCR.

RESULTS

Four SNPs were associated or possibly associated with TOLF, with higher pathogenic allele and genotype frequencies seen in TOLF patients compared with controls. The rs17551710/rs7671-GG/GG genotype appeared to be related to disease severity. Nucleotide substitutions at rs17551710 and rs7671 increased COL6A1 transcriptional activity and nucleotide substitutions at rs1053312 and rs13051496 increased COL6A1 protein expression. COL6A1 mRNA expression was significantly up-regulated in individuals with rs17551710/rs7671-GG/GG and rs1053312/rs13051496-AA+AG/CC genotypes compared with other genotypes.

CONCLUSION

SNPs in the COL6A1 promoter and exonic regions are associated with TOLF in the Chinese Han population, and lead to up-regulated COL6A1 expression. We confirmed COL6A1 as a TOLF susceptibility gene that may be involved in TOLF pathology.

SIRT6 Promotes Osteogenic Differentiation of Adipose-Derived Mesenchymal Stem Cells Through Antagonizing DNMT1

Background

Adipose-derived stem cells (ADSCs) are increasingly used in regenerative medicine because of their potential to differentiate into multiple cell types, including osteogenic lineages. Sirtuin protein 6 (SIRT6) is a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase that plays important roles in cell differentiation. NOTCH signaling has also been reported to involve in osteogenic differentiation. However, the function of SIRT6 in osteogenic differentiation of ADSCs and its relation to the NOTCH signaling pathways are yet to be explored.

Methods

The in vitro study with human ADSCs (hADSCs) and in vivo experiments with nude mice have been performed. Alkaline phosphatase (ALP) assays and ALP staining were used to detect osteogenic activity. Alizarin Red staining was performed to detect calcium deposition induced by osteogenic differentiation of ADSCs. Western blot, RT-qPCR, luciferase reporter assay, and co-immunoprecipitation assay were applied to explore the relationship between of SIRT6, DNA methyltransferases (DNMTs) and NOTCHs.

Results

SIRT6 promoted ALP activity, enhanced mineralization and upregulated expression of osteogenic-related genes of hADSCs in vitro and in vivo. Further mechanistic studies showed that SIRT6 deacetylated DNMT1, leading to its unstability at protein level. The decreased expression of DNMT1 prevented the abnormal DNA methylation of NOTCH1 and NOTCH2, resulting in the upregulation of their transcription. SIRT6 overexpression partially suppressed the abnormal DNA methylation of NOTCH1 and NOTCH2 by antagonizing DNMT1, leading to an increased capacity of ADSCs for their osteogenic differentiation.

Conclusion

This study demonstrates that SIRT6 physical interacts with the DNMT1 protein, deacetylating and destabilizing DNMT1 protein, leading to the activation of NOTCH1 and NOTCH2, Which in turn promotes the osteogenic differentiation of ADSCs.

Down-regulated microRNA-199a-3p enhances osteogenic differentiation of bone marrow mesenchymal stem cells by targeting Kdm3a in ovariectomized rats

Osteoporosis is a prevalent systemic skeletal disorder entailing bone fragility and increased fracture risk, often emerging in post-menopausal life. Emerging evidence implicates the dysregulation of microRNAs (miRNAs or miRs) in the progression of osteoporosis. This study investigated the effect of miR-199a-3p on osteoporosis and its underlying mechanism. We first examplished an ovariectomized (OVX)-induced rat osteoporosis model, and then isolated mesenchymal stem cells (MSCs) from bone marrow of the model rats. The overexpression and knock down of miR-199a-3p were conducted in OVX rats and MSCs to verify the role of miR-199a-3p on MSC differentiation. Calcium nodules were measured using alizarin red S (ARS) staining. RT-qPCR and Western blot assay were performed to measure the expression of miR-199a-3p, Kdm3a and osteogenic differentiation-related markers in rat tissues and cells. The correlation between miR-199a-3p and Kdm3a was confirmed using dual-luciferase reporter assay. The enrichment of Kdm3a at the Erk2 and Klf2 promoter was assessed using chromatin immunoprecipitation (ChIP) assay. Isolated MSCs were positive for CD29, CD44, CD90, and CD45, suggesting successful isolation of MSCs. There was increased expression of miR-199a-3p and inhibited osteogenic differentiation in OVX rats. Kdm3a was negatively targeted by miR-199a-3p. Our results also demonstrated that Kdm3a elevated the expression of Erk2 and Erk2 by promoting Erk2 and Klf2 demethylation, which further contributed to osteogenic differentiation. Overall, our results revealed a regulatory network of miR-199a-3p in osteogenic differentiation, highlighting miR-199a-3p as a potential target for therapeutic interventions in osteoporosis.

Dysregulation of MicroRNAs in Hypertrophy and Ossification of Ligamentum Flavum: New Advances, Challenges, and Potential Directions

Pathological changes in the ligamentum flavum (LF) can be defined as a process of chronic progressive aberrations in the nature and structure of ligamentous tissues characterized by increased thickness, reduced elasticity, local calcification, or aggravated ossification, which may cause severe myelopathy, radiculopathy, or both. Hypertrophy of ligamentum flavum (HLF) and ossification of ligamentum flavum (OLF) are clinically common entities. Though accumulated evidence has indicated both genetic and environmental factors could contribute to the initiation and progression of HLF/OLF, the definite pathogenesis remains fully unclear. MicroRNAs (miRNAs), one of the important epigenetic modifications, are short single-stranded RNA molecules that regulate protein-coding gene expression at posttranscriptional level, which can disclose the mechanism underlying diseases, identify valuable biomarkers, and explore potential therapeutic targets. Considering that miRNAs play a central role in regulating gene expression, we summarized current studies from the point of view of miRNA-related molecular regulation networks in HLF/OLF. Exploratory studies revealed a variety of miRNA expression profiles and identified a battery of upregulated and downregulated miRNAs in OLF/HLF patients through microarray datasets or transcriptome sequencing. Experimental studies validated the roles of specific miRNAs (e.g., miR-132-3p, miR-199b-5p in OLF, miR-155, and miR-21 in HLF) in regulating fibrosis or osteogenesis differentiation of LF cells and related target genes or molecular signaling pathways. Finally, we discussed the perspectives and challenges of miRNA-based molecular mechanism, diagnostic biomarkers, and therapeutic targets of HLF/OLF.

Human Induced Pluripotent Stem Cell-Derived Exosomes as a New Therapeutic Strategy for Various Diseases

Recently, an increasing number of studies have demonstrated that induced pluripotent stem cells (iPSCs) and iPSC-derived cells display therapeutic effects, mainly via the paracrine mechanism in addition to their transdifferentiation ability. Exosomes have emerged as an important paracrine factor for iPSCs to repair injured cells through the delivery of bioactive components. Animal reports of iPSC-derived exosomes on various disease models are increasing, such as in heart, limb, liver, skin, bone, eye and neurological disease and so forth. This review aims to summarize the therapeutic effects of iPSC-derived exosomes on various disease models and their properties, such as angiogenesis, cell proliferation and anti-apoptosis, with the hopes of improving their potential role in clinical applications and functional restoration.

SIRT6 enhances telomerase activity to protect against DNA damage and senescence in hypertrophic ligamentum flavum cells from lumbar spinal stenosis patients

Lumbar spinal stenosis (LSS) is a condition wherein patients exhibit age-related fibrosis, elastin-to-collagen ratio reductions, and ligamentum flavum hypertrophy. This study was designed to assess the relationship between SIRT6 and telomerase activity in hypertrophic ligamentum flavum (LFH) cells from LSS patients. We observed significant reductions in SIRT6, TPP1, and POT1 protein levels as well as increases in telomerase reverse transcriptase (TERT) levels and telomerase activity in LFH tissues relative to non- hypertrophic ligamentum flavum (LFN) tissues. When SIRT6 was overexpressed in these LFH cells, this was associated with significant increases in telomerase activity and a significant reduction in fibrosis-related protein expression. These effects were reversed, however, when telomerase activity was inactivated by hTERT knockdown in these same cells. SIRT6 overexpression was further found to reduce the frequency of senescence-associated β-galactosidase (SA-β-Gal)-positive LFH cells and to decrease p16, MMP3, and L1 mRNA levels and telomere dysfunction-induced foci (TIFs) in LFH cells. In contrast, hTERT knockdown-induced telomerase inactivation eliminated these SIRT6-dependent effects. Overall, our results indicate that SIRT6 functions as a key protective factor that prevents cellular senescence and telomere dysfunction in ligamentum flavum cells, with this effect being at least partially attributable to SIRT6-dependent telomerase activation.

Overexpressed miR-335-5p reduces atherosclerotic vulnerable plaque formation in acute coronary syndrome

BACKGROUND

Acute coronary syndrome (ACS) may induce cardiovascular death. The correlation of mast cells related microRNAs (miRs) with risk of ACS has been investigated. We explored regulatory mechanism of miR-335-5p on macrophage innate immune response, atherosclerotic vulnerable plaque formation, and revascularization in ACS in relation to Notch signaling.

METHODS

ACS-related gene microarray was collected from Gene Expression Omnibus database. After different agomir or antagomir, or inhibitor of Notch signaling treatment, IL-6, IL-1β, TNF-α, MCP-1, ICAM-1, and VCAM-1 levels were tested in ACS mice. Additionally, Notch signaling-related genes and matrix metalloproteinases (MMPs) were measured after miR-335-5p interference. Finally, mouse atherosclerosis, lipid accumulation, and the collagen/vessel area ratio of plaque were determined.

RESULTS

miR-335-5p targeted JAG1 and mediated Notch signaling in ACS. miR-335-5p up-regulation and Notch signaling inhibition reduced expression of JAG1, Notch pathway-related genes, IL-6, IL-1β, TNF-α, MCP-1, ICAM-1, VCAM-1, and MMPs, but promote TIMP1 and TIMP2 expression. Additionally, vulnerable plaques were decreased and collagen fiber contents were observed to increase after miR-335-5p overexpression and Notch signaling inhibition.

CONCLUSIONS

Overexpression of miR-335-5p inhibited innate immune response of macrophage, reduced atherosclerotic vulnerable plaque formation, and promoted revascularization in ACS mice targeting JAG1 through Notch signaling.

Overexpressed miR-335-5p reduces atherosclerotic vulnerable plaque formation in acute coronary syndrome

BACKGROUND

Acute coronary syndrome (ACS) may induce cardiovascular death. The correlation of mast cells related microRNAs (miRs) with risk of ACS has been investigated. We explored regulatory mechanism of miR-335-5p on macrophage innate immune response, atherosclerotic vulnerable plaque formation, and revascularization in ACS in relation to Notch signaling.

METHODS

ACS-related gene microarray was collected from Gene Expression Omnibus database. After different agomir or antagomir, or inhibitor of Notch signaling treatment, IL-6, IL-1β, TNF-α, MCP-1, ICAM-1, and VCAM-1 levels were tested in ACS mice. Additionally, Notch signaling-related genes and matrix metalloproteinases (MMPs) were measured after miR-335-5p interference. Finally, mouse atherosclerosis, lipid accumulation, and the collagen/vessel area ratio of plaque were determined.

RESULTS

miR-335-5p targeted JAG1 and mediated Notch signaling in ACS. miR-335-5p up-regulation and Notch signaling inhibition reduced expression of JAG1, Notch pathway-related genes, IL-6, IL-1β, TNF-α, MCP-1, ICAM-1, VCAM-1, and MMPs, but promote TIMP1 and TIMP2 expression. Additionally, vulnerable plaques were decreased and collagen fiber contents were observed to increase after miR-335-5p overexpression and Notch signaling inhibition.

CONCLUSIONS

Overexpression of miR-335-5p inhibited innate immune response of macrophage, reduced atherosclerotic vulnerable plaque formation, and promoted revascularization in ACS mice targeting JAG1 through Notch signaling.

Non-coding RNAs in ossification of spinal ligament

PURPOSE

Ossification of the spinal ligament (OSL) is a disease characterized by progressive ectopic ossification or calcification in the tissues of spinal ligament. The molecular pathogenesis of OSL has not been clearly elucidated. Recently, ncRNAs was found to functionally participate in OSL development. This review summarized current knowledge regarding the deregulation and function of ncRNAs in OSL METHODS: Relevant studies on deregulation and function of ncRNAs in OSL were retrieved from the PubMed databases. Then, studies were manually selected for inclusion based on predefined criteria.

RESULT

14 studies were reviewed, with 4 studies about high throughput sequencing and microarray of ncRNAs, 8 studies relevant to the function of ncRNAs and 2 studies regarding the ncRNAs as the biomarker of OSL.

CONCLUSION

ncRNA play a vital role in the ossification of spinal ligament fibrocyte, including cell osteogenesis and inflammation. ncRNAs also have potential clinical utilities as therapeutic targets, risk predication and early detection in the management of OSL.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Long noncoding RNA AK039312 and AK079370 inhibits bone formation via miR-199b-5p

Osteoporosis caused by aging and menopause had become an emerging threat to human health. The reduction of osteoblast differentiation has been considered to be an essential cause of osteoporosis. Osteoblast differentiation could be regulated by LncRNAs, and increasing evidences have proved that LncRNAs may be adopted as potential therapeutic targets for osteoporosis. However, reports on rescue effects of LncRNAs in vivo are relatively limited. In this study, two LncRNAs (AK039312 and AK079370) were screened as osteogenic related LncRNAs. Both AK039312 and AK079370 could inhibit osteoblast differentiation and bone formation through suppressing osteogenic transcription factors. This inhibitory effect was achieved via binding and sequestering miR-199b-5p, and enhanced GSK-3β which further inhibited wnt/β-catenin pathway. Moreover, the siRNAs of AK039312 and AK079370 significantly alleviated postmenopausal osteoporosis, and the combination of si-AK039312 and si-AK079370 was more efficient than applying one si-LncRNA alone. This study has provided new insights for the therapy of osteoporosis.

miR-199b-5p promoted chondrogenic differentiation of C3H10T1/2 cells by regulating JAG1

Mesenchymal stem cells (MSCs) are considered a promising candidate for use in cell-based therapy for cartilage repair. To promote understanding of the molecular control of chondrogenesis differentiation in MSCs, we compared the changes in microRNAs during in vitro chondrogenesis process of human bone-marrow mesenchymal stem cells (hBMSCs). MiR-199b-5p was up-regulated significantly during this process. The aim of the study was to investigate the effects of miR-199b-5p on chondrogenic differentiation of C3H10T1/2 MSC cells and explore the underlying mechanisms. MiR-199b-5p mimics or inhibitor were transfected into C3H10T1/2 cells, respectively, and then, the effects of miR-199b-5p on chondrogenic differentiation of C3H10T1/2 cells were detected. The results indicated that miR-199b-5p overexpression inhibited the growth of C3H10T1/2 cells but promoted transforming growth factor-β3 (TGF-β3)-induced C3H10T1/2 cells of chondrogenic differentiation, as supported by enhancing the gene and protein expression of chondrocyte specific markers of SOX9, aggrecan, and collagen type II (Col2a1). In contrast, inhibiting miR-199b-5p notably promoted the proliferation of C3H10T1/2 cells but decreased chondrogenic differentiation. Furthermore, mechanism studies revealed that JAG1 was a direct target of miR-199b-5p by dual luciferase reporter assays. While silencing of JAG1 by isRNA resulted an increase of chondrogenic differentiation. Further, JAG1 knockdown was demonstrated to block the effect of miR-199b-5p inhibition. In conclusion, the present study revealed for the first time that miR-199b-5p was the positive regulators to modulate chondrogenic differentiation of C3H10T1/2 cells by targeting JAG1. These findings may provide a novel insight on miRNA-mediated MSC therapy for cartilage related disorders.

miR-29a-5p Targets SATB2 and Regulates the SIRT1/Smad3 Deacetylation Pathway to Inhibit Thoracic Ligamentum Flavum Cell Osteogenesis

STUDY DESIGN

Experimental analysis of the thoracic ligamentum flavum cell osteogenic differentiation process.

OBJECTIVE

This study aimed to explore the role of miR-29a-5p and special AT-rich sequence-binding protein 2 (SATB2) in a pathological osteogenic process.

SUMMARY OF BACKGROUND DATA

Thoracic ossification of the ligamentum flavum (TOLF) is an uncommon disease wherein ligaments within the spine undergo progressive ossification, resulting in stenosis of the spinal canal and myelopathy. MiR-29a-5p was found to be downregulated in ligament cells from ossified ligament tissue in a previous study. However, whether miR-29a-5p is involved in the process of TOLF has not been investigated.

METHODS

The expression of miR-29a-5p in ligament tissues or in the context of TOLF osteogenic cell differentiation was measured via qRT-PCR. Alkaline phosphatase activity assay and Alizarin red staining were used to analyze cellular osteogenesis. The protein-level expression of SATB2, SIRT1, and Smad3 were measured via immunohistochemistry or western blotting. Dual luciferase reporter assays and western blotting were used to confirm that miR-29a targets SATB2.

RESULTS

SATB2 was found to be upregulated and miR-29a-5p was downregulated in TOLF tissue. We additionally observed decreased miR-29a-5p expression during the process of TOLF osteogenic cell differentiation, and there was a marked reduction in the expression of key mediators of osteogenesis when miR-29a-5p was overexpressed. Consistent with this, when miR-29a-5p was inhibited this led to enhanced osteogenic cell differentiation of these cells. We further found miR-29a-5p to directly target and suppress the expression of SATB2. Knock-down of SATB2 was sufficient to reduce the ability of miR-29a-5p to inhibit osteogenesis, and this also led to decreased SIRT1 expression and Smad3 acetylation.

CONCLUSION

Together our findings indicate that miR-29a-5p is able to prevent thoracic ligamentum flavum cell osteogenesis at least in part via targeting SATB2 and thereby suppressing the SIRT1/Smad3 deacetylation pathway.

LEVEL OF EVIDENCE

N/A.

MicroRNAs-containing extracellular vesicles in bone remodeling: An emerging frontier

Bone remodeling is a complex and constant process, which is maintained by well-regulated communication among various cells. Extracellular vesicles (EVs) are small vesicles, which could provide a protective environment for the transportation of various functional molecules. It has been shown that EVs could dock with distant and/or neighboring target cells, deliver cargoes to these specific cells and alter their fates. MicroRNAs (miRNAs), single-stranded non-coding RNAs with 22-26 nucleotides, could bind to mRNAs and repress the translation or stimulate the degradation of mRNAs. It is reported that EVs could serve as the mail carriers, which could cargo miRNAs to exchange information between different cells and act through a novel way to regulate signaling pathways during bone remodeling. In this review, we summarize the function of EV-miRNAs in the communication among mesenchymal stem cells (MSCs), osteoblasts, osteoclasts, osteocytes, and myoblasts during bone remodeling, as well as the key signaling molecules which are involved in this process. The roles of EV-miRNAs in sending intercellular messages in the microenvironment of bone remodeling could shed new light on the development of tissue engineering, and provide novel diagnostic markers and therapeutic targets of bone-related diseases.

Identification of crucial miRNAs and lncRNAs for ossification of ligamentum flavum

The present study aimed to screen crucial micro (mi)RNAs and long non-coding (lnc)RNAs involved in the development of ossification of ligamentum flavum (OLF) based on the miRNA-mRNA and lncRNA-miRNA-mRNA competing endogenous (ce)RNA regulatory network analyses, which are rarely reported. The differentially expressed genes (DEGs), differentially expressed lncRNAs (DELs) and differentially expressed miRNAs (DEMs) between 4 OLF and 4 healthy controls were identified using two microarray datasets GSE106253 and GSE106256 collected from the Gene Expression Omnibus database. A protein-protein interaction (PPI) network was constructed, followed by calculation of topological characteristics and sub-module analysis in order to obtain hub DEGs. The miRNA-mRNA and lncRNA-miRNA networks that were established based on their interaction pairs, obtained from miRwalk and starBase databases, respectively, were integrated to form the ceRNA network. The underlying functions of mRNAs were predicted using the Database for Annotation, Visualization and Integrated Discovery (DAVID). The present study screened 828 DEGs, 119 DELs and 81 DEMs between OLF and controls. PPI network and module analyses identified interleukin (IL)10, adenylate cyclase (ADCY)5, suppressor of cytokine signaling (SOCS)3, G protein subunit gamma (GNG) 4, collagen type II α 1 chain (COL2A1) and collagen type XIII α 1 chain (COL13A1) as hub genes. The miRNA-mRNA network analysis demonstrated IL10 could be regulated by miR-210-3p, while COL13A1 and COL2A1 could be modulated by miR-329-3p and miR-222-5p, respectively. lncRNA-miRNA-mRNA ceRNA network analysis identified that small nucleolar RNA host gene 16-hsa-miR-196a-5p-SOCS3, ankyrin repeat and SOCS box containing 16-AS1-hsa-miR-379-5p-GNG4, nuclear enriched abundant transcript 1-has-miR-181b-5p-ADCY5, rhophilin 1-AS1-hsa-miR-299-3p-WNT7B interaction axes may be crucial. DAVID analysis predicted IL10, ADCY5, GNG4 and SOCS3 were involved in ‘adaptive immune response’, ‘Chemokine signaling pathway’ and ‘regulation of apoptosis’ processes, while COL2A1, COL13A1 and WNT7B may be ossification related. In conclusion, the identification of these crucial miRNAs and lncRNAs may be conducive for explaining the pathogenesis of OLF and provide certain natural, endogenous and nontoxic drug targets for the treatment of OLF.

Role of microRNAs in osteogenesis of stem cells

Osteogenic differentiation is a controlled developmental process in which external and internal factors including cytokines, growth factors, transcription factors (TFs), signaling pathways and microRNAs (miRNAs) play important roles. Various stimulatory and inhibitory TFs contribute to osteogenic differentiation and are responsible for bone development. In addition, cross-talk between several complex signaling pathways regulates the osteogenic differentiation of some stem cells. Although much is known about regulatory genes and signaling pathways in osteogenesis, the role of miRNAs in osteogenic differentiation still needs to be explored. miRNAs are small, approximately 22 nucleotides, single-stranded nonprotein coding RNAs which are abundant in many mammalian cell types. They paly significant regulated roles in various biological processes and serve as promising biomarkers for disease states. Recently, emerging evidence have shown that miRNAs are the key regulators of osteogenesis of stem cells. They may endogenously regulate osteogenic differentiation of stem cells through direct targeting of positive or negative directors of osteogenesis and depending on the target result in the promotion or inhibition of osteogenic differentiation. This review aims to provide a general overview of miRNAs participating in osteogenic differentiation of stem cells and explain their regulatory effect based on the genes targeted with these miRNAs.

Exosomes Derived from Human Induced Pluripotent Stem Cells-Endothelia Cells Promotes Postnatal Angiogenesis in Mice Bearing Ischemic Limbs

Induced pluripotent stem cell (iPSC) derived endothelial cells (ECs) is a novel therapeutic option for ischemic diseases. Although the detailed mechanism of this novel therapy remains unknown, emerging evidence has demonstrated that exosomes derived from hiPSC-ECs play a critical role in this approach. In this study, we first isolated and characterized the exosomes from iPSCs-ECs (hiPSC-EC-Exo) and determined the functional roles of hiPSC-EC-Exo in neovascularization and the underlying mechanism. Further, we evaluated the effect of exosomes derived from hiPS-ECs on promoting angiogenesis in a mouse model bearing ischemic limbs. Our results showed that miR-199b-5p, an miRNA highly associated with angiogenesis, is significantly upregulated during the differentiation of hiPSC-ECs. Mechanically, our studies found that hiPSC-ECs expressing miR-199b-5p significantly promote cell migration, proliferation and tube formation through Jagged-1-dependent upregulation of VEGFR2 in HUVECs. Similarly, coculture of hiPSC-ECs-Exo with HUVECs also resulted in a significant improvement in HUVEC migration, proliferation, and tube formation, suggesting that exosome-mediated cell-cell communication in a paracrine manner may serve as a fundamental mechanism for iPSC-EC-based treatment. Consequently, we found that the transfer of hiPSC-ECs enriched with miR-199b-5p significantly enhanced micro-vessel density and blood perfusion in ischemic limbs in vivo. Taken together, our studies were the first to demonstrate that transfer of hiPSC-ECs-Exo is a promising approach to treat ischemic injury via the mechanism of promoting neovascularization.

Angiopoietin-2 promotes osteogenic differentiation of thoracic ligamentum flavum cells via modulating the Notch signaling pathway

Thoracic ossification of the ligamentum flavum (TOLF) is heterotopic ossification of spinal ligaments, which may cause serious thoracic spinal canal stenosis and myelopathy. However, the underlying etiology remains inadequately understood. In this study, the ossification patterns of TOLF were analyzed by micro-computer tomography (micro-CT). The expression profile of genes associated with angiogenesis was analyzed in thoracic ligamentum flavum cells at sites of different patterns of ossification using RNA sequencing. Significant differences in the expression profile of several genes were identified from Gene Ontology (GO) analysis. Angiopoietin-2 (ANGPT2) was significantly up-regulated in primary thoracic ligamentum flavum cells during osteogenic differentiation. To address the effect of ANGPT2 on Notch signaling and osteogenesis, ANGPT2 stimulation increased the expression of Notch2 and osteogenic markers of primary thoracic ligamentum flavum cells of immature ossification, while inhibition of ANGPT2 exhibited opposite effect on Notch pathway and osteogenesis of cells of mature ossification. These findings provide the first evidence for positive regulation of ANGPT2 on osteogenic differentiation in human thoracic ligamentum flavum cells via modulating the Notch signaling pathway.

MicroRNA-145 induces apoptosis of glioma cells by targeting BNIP3 and Notch signaling

MicroRNAs (miRNAs) are involved in the pathogenesis of various human cancers. Here we show that miR-145 expression is decreased in human glioma samples, rat glioma tissues, and glioma cell lines, while expression of BNIP3 is increased. Over-expression of miR-145 or suppression of BNIP3 induced glioma cell apoptosis. BNIP3 is localized in the nucleus in glioma cells, and miR-145 inhibits BNIP3 expression by binding to the 3’ untranslated region of its mRNA. Interestingly, miR-145 and BNIP3 regulate glioma cell apoptosis by modulating Notch signaling. These results indicate that miR-145 increases glioma cell apoptosis by inhibiting BNIP3 and Notch signaling, and suggest that miR-145 may serve as a novel therapeutic target for malignant glioma.