Stromal cell-derived factor-1 promotes osteoblastic differentiation of human bone marrow mesenchymal stem cells via the lncRNA-H19/miR-214-5p/BMP2 axis

N6-Methyladenosine in Cell-Fate Determination of BMSCs: From Mechanism to Applications

The methylation of adenosine base at the nitrogen-6 position is referred to as "N6-methyladenosine (m6A)" and is one of the most prevalent epigenetic modifications in eukaryotic mRNA and noncoding RNA (ncRNA). Various m6A complex components known as "writers," "erasers," and "readers" are involved in the function of m6A. Numerous studies have demonstrated that m6A plays a crucial role in facilitating communication between different cell types, hence influencing the progression of diverse physiological and pathological phenomena. In recent years, a multitude of functions and molecular pathways linked to m6A have been identified in the osteogenic, adipogenic, and chondrogenic differentiation of bone mesenchymal stem cells (BMSCs). Nevertheless, a comprehensive summary of these findings has yet to be provided. In this review, we primarily examined the m6A alteration of transcripts associated with transcription factors (TFs), as well as other crucial genes and pathways that are involved in the differentiation of BMSCs. Meanwhile, the mutual interactive network between m6A modification, miRNAs, and lncRNAs was intensively elucidated. In the last section, given the beneficial effect of m6A modification in osteogenesis and chondrogenesis of BMSCs, we expounded upon the potential utility of m6A-related therapeutic interventions in the identification and management of human musculoskeletal disorders manifesting bone and cartilage destruction, such as osteoporosis, osteomyelitis, osteoarthritis, and bone defect.

LINC01638 sustains human mesenchymal stem cell self-renewal and competency for osteogenic cell fate

The skeleton forms from multipotent human mesenchymal stem cells (hMSCs) competent to commit to specific lineages. Long noncoding RNAs (lncRNAs) have been identified as key epigenetic regulators of tissue development. However, regulation of osteogenesis by lncRNAs as mediators of commitment to the bone phenotype is largely unexplored. We focused on LINC01638, which is highly expressed in hMSCs and has been studied in cancers, but not in regulating osteogenesis. We demonstrated that LINC01638 promotes initiation of the osteoblast phenotype. Our findings reveal that LINC01638 is present at low levels during the induction of osteoblast differentiation. CRISPRi knockdown of LINC01638 in MSCs prevents osteogenesis and alkaline phosphatase expression, inhibiting osteoblast differentiation. This resulted in decreased MSC growth rate, accompanied by double-strand breaks, DNA damage, and cell senescence. Transcriptome profiling of control and LINC01638-depleted hMSCs identified > 2000 differentially expressed mRNAs related to cell cycle, cell division, spindle formation, DNA repair, and osteogenesis. Using ChIRP-qPCR, molecular mechanisms of chromatin interactions revealed the LINC01638 locus (Chr 22) includes many lncRNAs and bone-related genes. These novel findings identify the obligatory role for LINC01638 to sustain MSC pluripotency regulating osteoblast commitment and growth, as well as for physiological remodeling of bone tissue.

Hsa-miR-27b-5p suppresses the osteogenic and odontogenic differentiation of stem cells from human exfoliated deciduous teeth via targeting BMPR1A: An ex vivo study

AIM

Recently, miR-27b-5p was shown to be abundantly expressed in extracellular vehicles (EVs) from the inflammatory microenvironment. This study determined the role of miR-27b-5p in regulating osteogenic and odontogenic differentiation of stem cells from human exfoliated deciduous teeth (SHEDs) and further examined the regulatory mechanism of bone morphogenetic protein receptor type-1A (BMPR1A).

METHODOLOGY

Characteristics of SHEDs and SHEDs-EVs derived from SHEDs were evaluated respectively. The expression of miR-27b-5p in SHEDs and EVs was detected during osteo-induction. Mechanically, SHEDs were treated with miR-27b-5p mimics or an inhibitor, and the osteogenic/odontogenic differentiation and proliferation were assessed. Bioinformatic analysis and luciferase reporter were utilized for target gene prediction and verification. Finally, BMPR1A-overexpressed plasmids were transfected into SHEDs to investigate the participation of the BMPR1A/SMAD4 pathway. Data were analysed using Student's t-test, one-way analysis of variance and Chi-square test.

RESULTS

MiR-27b-5p was expressed in both SHEDs and EVs and was significantly increased at the initial stage of differentiation and then decreased in a time-dependent manner (p < .01). Upregulation of miR-27b-5p significantly suppressed osteogenic/odontogenic differentiation of SHEDs and inhibited proliferation (p < .05), whereas inhibition of miR-27b-5p enhanced the differentiation (p < .05). Dual-luciferase reporter assay and pull-down assay confirmed the binding site between miR-27b-5p and BMPR1A (p < .05). The overexpression of BMPR1A rescued the effect of miR-27b-5p, while contributed to the decrease of pluripotency (p < .05). Additionally, miR-27b-5p maintained pluripotency in BMPR1A-overexpressed SHEDs (p < .05).

CONCLUSIONS

MiR-27b-5p in SHEDs/EVs was inversely associated with differentiation and suppressed the osteogenic and odontogenic differentiation of SHEDs and maintained the pluripotency of SHEDs partly by shuttering BMPR1A-targeting BMP signalling. Theoretically, inhibition of miR-27b-5p represents a potential strategy to promote osteanagenesis and dentinogenesis. However, miR-27b-5p capsuled EVs might maintain cell pluripotency and self-renewal for non-cell-targeted therapy.

miR-126 mitigates the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells by targeting the ERK1/2 and Bcl-2 pathways

Human bone marrow mesenchymal stem cells (hBMMSCs) are a promising cell source for bone engineering owing to their high potential to differentiate into osteoblasts. The objective of the present study is to assess microRNA-126 (miR-126) and examine its effects on the osteogenic differentiation of hBMMSCs. In this study, we investigate the role of miR-126 in the progression of osteogenic differentiation (OD) as well as the apoptosis and inflammation of hBMMSCs during OD induction. OD is induced in hBMMSCs, and matrix mineralization along with other OD-associated markers are evaluated by Alizarin Red S (AR) staining and quantitative PCR (qPCR). Gain- and loss-of-function studies are performed to demonstrate the role of miR-126 in the OD of hBMMSCs. Flow cytometry and qPCR-based cytokine expression studies are performed to investigate the effect of miR-126 on the apoptosis and inflammation of hBMMSCs. The results indicate that miR-126 expression is downregulated during the OD of hBMMSCs. Gain- and loss-of function assays reveal that miR-126 upregulation inhibits the differentiation of hBMMSCs into osteoblasts, whereas the downregulation of miR-126 promotes hBMMSC differentiation, as assessed by the determination of osteogenic genes and alkaline phosphatase activity. Furthermore, the miR-126 level is positively correlated with the production of inflammatory cytokines and apoptotic cell death. Additionally, our results suggest that miR-126 negatively regulates not only B-cell lymphoma 2 (Bcl-2) expression but also the phosphorylation of extracellular signal‑regulated protein kinase (ERK) 1/2. Moreover, restoring ERK1/2 activity and upregulating Bcl-2 expression counteract the miR-126-mediated suppression of OD in hBMMSCs by promoting inflammation and apoptosis, respectively. Overall, our findings suggest a novel molecular mechanism relevant to the differentiation of hBMMSCs into osteoblasts, which can potentially facilitate bone formation by counteracting miR-126-mediated suppression of ERK1/2 activity and Bcl-2 expression.

Role of mechano-sensitive non-coding RNAs in bone remodeling of orthodontic tooth movement: recent advances

Orthodontic tooth movement relies on bone remodeling and periodontal tissue regeneration in response to the complicated mechanical cues on the compressive and tensive side. In general, mechanical stimulus regulates the expression of mechano-sensitive coding and non-coding genes, which in turn affects how cells are involved in bone remodeling. Growing numbers of non-coding RNAs, particularly mechano-sensitive non-coding RNA, have been verified to be essential for the regulation of osteogenesis and osteoclastogenesis and have revealed how they interact with signaling molecules to do so. This review summarizes recent findings of non-coding RNAs, including microRNAs and long non-coding RNAs, as crucial regulators of gene expression responding to mechanical stimulation, and outlines their roles in bone deposition and resorption. We focused on multiple mechano-sensitive miRNAs such as miR-21, - 29, -34, -103, -494-3p, -1246, -138-5p, -503-5p, and -3198 that play a critical role in osteogenesis function and bone resorption. The emerging roles of force-dependent regulation of lncRNAs in bone remodeling are also discussed extensively. We summarized mechano-sensitive lncRNA XIST, H19, and MALAT1 along with other lncRNAs involved in osteogenesis and osteoclastogenesis. Ultimately, we look forward to the prospects of the novel application of non-coding RNAs as potential therapeutics for tooth movement and periodontal tissue regeneration.

Fluid Shear Stress Promotes Osteoblast Proliferation and Suppresses Mitochondrial-Mediated Osteoblast Apoptosis Through the miR-214-3p-ATF4 Signaling Axis

MicroRNAs (miRNAs) play vital roles in bone metabolism and participate in the mechanically induced bone alterations. The underlying molecular mechanisms by which fluid shear stress (FSS) regulate the proliferative and apoptotic phenotypic changes of osteoblasts remain elusive. The study aimed to investigate the regulatory effects of FSS on osteoblast proliferative and apoptotic phenotypes and the roles of miR-214-3p-ATF4 (activating transcription factor 4) signaling axis in the mechanomodulation processes. FSS promoted the proliferative activity of osteoblasts and suppressed mitochondrial-mediated osteoblast apoptosis. FSS decreased miR-214-3p expression and increased ATF4 expression in MC3T3-E1 osteoblasts. MiR-214-3p inhibited osteoblast proliferative activity and promoted mitochondrial-mediated osteoblast apoptosis. Overexpression of miR-214-3p attenuated FSS-enhanced osteoblast proliferation and FSS-suppressed mitochondrial-mediated osteoblast apoptosis. We validated that ATF4 acted as a target gene of miR-214-3p. Moreover, miR-214 3p regulated osteoblast proliferation and apoptosis through targeting ATF4. Taken together, our study proved that FSS could suppress mitochondrial-mediated osteoblast apoptosis and promote osteoblast proliferation through the miR-214-3p-ATF4 signaling axis.

The lncRNA DANCR promotes development of atherosclerosis by regulating the miR-214-5p/COX20 signaling pathway

BACKGROUND

Although long non-coding RNA differentiation antagonizing non-protein coding RNA (DANCR) has been reported to be involved in atherosclerosis (AS) development, its specific mechanism remains unclear.

METHODS

DANCR expression levels in blood samples of AS patients and oxidized low-density lipoprotein (ox-LDL) treated vascular smooth muscle cells (VSMCs) and human umbilical vein endothelial cells (HUVECs) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The small interfering RNA targeting DANCR (si-DANCR) was used to silence DANCR expression. Cell viability was assessed by CCK-8 assay. Cell apoptosis was evaluated by flow cytometry. Levels of inflammatory cytokines, anti-oxidative enzyme superoxide dismutase (SOD) activity, and malonaldehyde (MDA) were detected by specific commercial kits. An animal AS model was established to confirm the role of DANCR/microR-214-5p/COX20 (the chaperone of cytochrome c oxidase subunit II COX2) in AS development.

RESULTS

DANCR was significantly increased in the blood samples of AS patients and ox-LDL treated VSMCs and HUVECs. DANCR downregulation obviously increased viability and reduced apoptosis of ox-LDL-treated VSMCs and HUVECs. Meanwhile, DANCR downregulation reduced the levels of inflammatory cytokines, including interleukin (IL)-6 (IL-6), IL-1beta (IL-1β), IL-6 and tumor necrosis factor (TNF)-alpha (TNF-α) and MDA while increasing the SOD level in ox-LDL-treated VSMCs and HUVECs. DANCR regulated COX20 expression by acting as a competing endogenous RNA (ceRNA) of miR-214-5p. Rescue experiments demonstrated that miR-214-5p downregulation obviously attenuated si-DANCR-induced protective effects on ox-LDL-caused endothelial injury.

CONCLUSIONS

Our results revealed that DANCR promoted AS progression by targeting the miR-214-5p/COX20 axis, suggesting that DANCR might be a potential therapeutic target for AS.

Differential lncRNA/mRNA Expression Profiling and Functional Network Analyses in Bmp2 Deletion of Mouse Dental Papilla Cells

Bmp2 is essential for dentin development and formation. Bmp2 conditional knock-out (KO) mice display a similar tooth phenotype of dentinogenesis imperfecta (DGI). To elucidate a foundation for subsequent functional studies of cross talk between mRNAs and lncRNAs in Bmp2-mediated dentinogenesis, we investigated the profiling of lncRNAs and mRNAs using immortalized mouse dental Bmp2 flox/flox (iBmp2^fx/fx) and Bmp2 knock-out (iBmp2^ko/ko) papilla cells. RNA sequencing was implemented to study the expression of the lncRNAs and mRNAs. Quantitative real-time PCR (RT-qPCR) was used to validate expressions of lncRNAs and mRNAs. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were used to predict functions of differentially expressed genes (DEGs). Protein-protein interaction (PPI) and lncRNA-mRNA co-expression network were analyzed by using bioinformatics methods. As a result, a total of 22 differentially expressed lncRNAs (16 downregulated vs 6 upregulated) and 227 differentially expressed mRNAs (133 downregulated vs. 94 upregulated) were identified in the iBmp2^ko/ko cells compared with those of the iBmp2^fx/fx cells. RT-qPCR results showed significantly differential expressions of several lncRNAs and mRNAs which were consistent with the RNA-seq data. GO and KEGG analyses showed differentially expressed genes were closely related to cell differentiation, transcriptional regulation, and developmentally relevant signaling pathways. Moreover, network-based bioinformatics analysis depicted the co-expression network between lncRNAs and mRNAs regulated by Bmp2 in mouse dental papilla cells and symmetrically analyzed the effect of Bmp2 during dentinogenesis via coding and non-coding RNA signaling.

Moderate-intensity treadmill running relieves motion-induced post-traumatic osteoarthritis mice by up-regulating the expression of lncRNA H19

BACKGROUND

The purpose of this study was to explore whether moderate-intensity exercise can alleviate motion-induced post-traumatic osteoarthritis (PTOA) and the expression change of lncRNA H19 during this progression.

METHODS

Twenty-week-old male C57BL/6 mice were randomly divided into five groups: model control group (MC group, n = 6), treadmill model group (M group, n = 6), rehabilitation control group (RC group, n = 6), treadmill model + rehabilitation training group (M + R group, n = 6) and treadmill model + convalescent group (M + C group, n = 6). Paraffin sections were used to observe the pathological changes in the mouse knee joint in each group. A micro-CT was used to scan the knee joint to obtain the morphological indexes of the tibial plateau bone. Real-time PCR was used to detect the mRNA levels of inflammatory factors, synthetic and catabolic factors in cartilage.

RESULTS

After high-intensity exercise for 4 weeks, the inflammation and catabolism of the mouse knee cartilage were enhanced, and the anabolism was weakened. Further study showed that these results were partially reversed after 4-week moderate-intensity training. The results of hematoxylin-eosin staining confirmed this finding. Meanwhile, high-intensity exercise reduced the expression of lncRNA H19 in cartilage, while the expression of lncRNA H19 increased after 4 weeks of moderate-intensity exercise.

CONCLUSION

High-intensity treadmill running can cause injury to the knee cartilage in C57BL/6 mice which leads to PTOA and a decrease of lncRNA H19 expression in cartilage. Moderate-intensity exercise can relieve PTOA and partially reverse lncRNA H19 expression.

Role of long non-coding RNA H19 in the development of osteoporosis

Background

Osteoporosis is a widespread and serious metabolic bone disease. At present, revealing the molecular mechanisms of osteoporosis and developing effective prevention and treatment methods are of great significance to health worldwide. LncRNA is a non-coding RNA peptide chain with more than 200 nucleotides. Researchers have identified many lncRNAs implicated in the development of diseases and lncRNA H19 is an example.

Results

A large amount of evidence supports the fact that long non-coding RNA (lncRNA) genes, such as H19, have multiple, far-reaching effects on various biological functions. It has been found that lncRNA H19 has a role in the regulation of different types of cells in the body including the osteoblasts, osteocytes, and osteoclasts found in bones. Therefore, it can be postulated that lncRNA H19 affects the incidence and development of osteoporosis.

Conclusion

The prospect of targeting lncRNA H19 in the treatment of osteoporosis is promising because of the effects that lncRNA H19 has on the process of osteogenic differentiation. In this review, we summarize the molecular pathways and mechanisms of lncRNA H19 in the pathogenesis of osteoporosis and summarize the research progress of targeting H19 as a treatment option. Research is emerging that explores more effective treatment possibilities for bone metabolism diseases using molecular targets.