lncRNA SNHG1 attenuates osteogenic differentiation via the miR‑101/DKK1 axis in bone marrow mesenchymal stem cells

The mechanism of lncRNA SNHG1 in osteogenic differentiation via miR-497-5p/ HIF1AN axis

The pivotal role of lncRNAs in osteoporosis progression and development necessitates a comprehensive exploration of the functional and precise molecular mechanisms underlying lncRNA SNHG1's regulation of osteoblast differentiation and calcification. The study involved inducing BMSCs cells to differentiate into osteoblasts, followed by transfections of miR-497-5p inhibitors, pcDNA3.1-SNHG1, sh-HIF1AN, miR-497-5p mimics, and respective negative controls into BMSCs. Quantitative PCR (qPCR) was employed to assess the expression of SNHG1 and miR-497-5p. Western Blotting was conducted to measure the levels of short stature-related transcription factor 2 (RUNX2), osteopontin (OPN), osteocalcin (OCN), and HIF1AN. Alkaline phosphatase (ALP) activity was determined using appropriate assay kits. Calcium nodule staining was performed through Alizarin red staining. Dual luciferase reporter gene assays were executed to validate the interaction between SNHG1 and miR-497-5p, as well as HIF1AN. Throughout osteogenic differentiation, there was a down-regulation of SNHG1 and HIF1AN, in contrast to an elevation in miR-497-5p levels. Direct interactions between miR-497-5p and both SNHG1 and HIF1AN were observed. Notably, SNHG1 exhibited the ability to modulate HIF1AN by influencing miR-497-5p, thereby inhibiting osteogenic differentiation. Functioning as a competitive endogenous RNA, lncRNA SNHG1 exerts an inhibitory influence on osteogenic differentiation via the miR-497-5p/HIF1AN axis. This highlights the potential for lncRNA SNHG1 to emerge as a promising therapeutic target for osteoporosis. The study's findings pave the way for a novel target strategy in the future treatment of osteoporosis.

Long Non-coding RNA SNHG1 Suppresses the Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells by Binding with HMGB1

Osteoporosis (OP) has a significant detrimental impact on the health of the elder. Long-term clinical effectiveness of current drugs used for OP treatment is limited. Therefore, it is very important to explore novel treatment targets for OP. The expression of SNHG1, HMGB1, OCN and OPN in gene level was measured using RT-qPCR, and the protein expression was determined by Western blotting assay. The concentration of IL-1β and IL-18 in supernatant of the bone marrow mesenchymal stem cells (BMSCs) was measured by ELISA. The interaction between SNHG1 and HMGB1 was confirmed by RNA pull down. Besides, alizarin red staining was performed to evaluate the differentiation of BMSCs into osteoblast. SNHG1 and HMGB1 were found to be upregulated in the serum of OP patients. During the osteogenic differentiation of BMSCs, the expression of osteoblastogenesis markers (OCN and OPN) and the activity of ALP were upregulated, while the expression levels of SNHG1 and HMGB1 were decreased in a time-dependent manner. In addition, the interaction between SNHG1 and HMGB1, expression of pyroptosis-associated factors (caspase-1 p20 and GSDMD-N), and secretion of IL-1β and IL-18 were also decreased during osteogenic differentiation. Interestingly, increasing SNHG1 promoted HMGB1 expression, activated pyroptosis, but inhibited osteogenic differentiation. Silencing HMGB1 or inhibiting caspase-1 partially rescued the inhibitory effect of SNHG1 on osteogenic differentiation. Our findings indicate that SNHG1 suppresses the osteogenic differentiation of BMSCs by activating pyroptosis through interaction with HMGB1 and promotion of HMGB1 expression. Our work provides further evidence supporting SNHG1 acts as a potential target for OP treatment, and reveals for the first time that SNHG1 regulates osteogenic differentiation by affecting pyroptosis.

Research progress on the role of lncRNA-miRNA networks in regulating adipogenic and osteogenic differentiation of bone marrow mesenchymal stem cells in osteoporosis

Osteoporosis (OP) is characterized by a decrease in osteoblasts and an increase in adipocytes in the bone marrow compartment, alongside abnormal bone/fat differentiation, which ultimately results in imbalanced bone homeostasis. Bone marrow mesenchymal stem cells (BMSCs) can differentiate into osteoblasts and adipocytes to maintain bone homeostasis. Several studies have shown that lncRNAs are competitive endogenous RNAs that form a lncRNA-miRNA network by targeting miRNA for the regulation of bone/fat differentiation in BMSCs; this mechanism is closely related to the corresponding treatment of OP and is important in the development of novel OP-targeted therapies. However, by reviewing the current literature, it became clear that there are limited summaries discussing the effects of the lncRNA-miRNA network on osteogenic/adipogenic differentiation in BMSCs. Therefore, this article provides a review of the current literature to explore the impact of the lncRNA-miRNA network on the osteogenic/adipogenic differentiation of BMSCs, with the aim of providing a new theoretical basis for the treatment of OP.

Long non-coding RNAs in osteoporosis: from mechanisms of action to therapeutic potential

Osteoporosis is a clinical disease characterized by decreased bone density due to a disrupted balance between bone formation and resorption, which increases fracture risk and negatively affects the quality of life of a patient. LncRNAs are RNA molecules over 200 nucleotides in length with non-coding potential. Many studies have demonstrated that numerous biological processes involved in bone metabolism are affected. However, the complex mechanisms of action of lncRNAs and their clinical applications in osteoporosis have not yet been fully elucidated. LncRNAs, as epigenetic regulators, are widely involved in the regulation of gene expression during osteogenic and osteoclast differentiation. LncRNAs affect bone homeostasis and osteoporosis development through different signaling pathways and regulatory networks. Additionally, researchers have found that lncRNAs have great potential for clinical application in the treatment of osteoporosis. In this review, we summarize the research results on lncRNAs for clinical prevention, rehabilitation treatment, drug development, and targeted therapy for osteoporosis. Moreover, we summarize the regulatory modes of various signaling pathways through which lncRNAs affect the development of osteoporosis. Overall, these studies suggest that lncRNAs can be used as novel targeted molecular drugs for the clinical treatment of osteoporosis to improve symptoms.

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.

Morinda officinalis polysaccharide enable suppression of osteoclastic differentiation by exosomes derived from rat mesenchymal stem cells

CONTEXT

Morinda officinalis F.C. How. (MO) (Rubiaceae) can strengthen bone function.

OBJECTIVE

To examine the functional mechanism and effect of MO polysaccharides (MOPs) in rats with glucocorticoid-induced osteoporosis (GIOP).

MATERIALS AND METHODS

Rats with GIOP were treated with 5, 15 or 45 mL/kg of MOP [n = 15 for each dose, intraperitoneal (i.p.) injection every other day for 8 weeks]. The body weight of rats and histomorphology of bone tissues were examined. Bone marrow mesenchymal stem cells (BMSCs)-derived exosomes (Exo) were collected and identified. Bone marrow-derived macrophages (BMMs) were induced to differentiate into osteoclasts and treated with BMSC-Exo for in vitro studies.

RESULTS

MOP reduced the body weight (5, 15, or 45 mg/kg MOP vs. phosphate-buffered saline: 8%, 15% and 25%, p < 0.01), elevated the bone volume to tissue volume (BV/TV), mean trabecular thickness (Tb.Th), mean trabecular number (Tb.N) and mean connectivity density (Conn.D) (40-86%, p < 0.01), decreased the mean trabecular separation/spacing (Tb.Sp) (22-37%, p < 0.01), increased the cortical bone continuity (35-90%, p < 0.01) and elevated RUNX family transcription factor 2 and RANK levels (5-12%, p < 0.01), but suppressed matrix metallopeptidase 9 and cathepsin K levels (9-20%, p < 0.01) in femur tissues. BMSC-Exo from MOP-treated rats (MOP-Exo) suppressed osteoclastic differentiation and proliferation of BMMs. The downregulation of microRNA-101-3p (miR-101-3p) or the upregulation of prostaglandin-endoperoxide synthase 2 (PTGS2) blocked the functions of MOP-Exo.

DISCUSSION AND CONCLUSIONS

MOP inhibits osteoclastic differentiation and could potentially be used for osteoporosis management. This suppression may be enhanced by the upregulation of miR-101-3p or the inhibition of PTGS2.

Bioinformatic analysis of the RNA expression patterns in microgravity-induced bone loss

Researchers have linked microgravity in space to the significant imbalance between bone formation and bone resorption that induces persistent bone loss in load-bearing bones. However, the underlying molecular mechanisms are still unclear, which hinders the development of therapeutic measures. The aim of this study was to identify hub genes and explore novel molecular mechanisms underlying microgravity-induced bone loss using transcriptome datasets obtained from the GEO and SRA databases. In summary, comparative RNA expression pattern studies that differ in species (Homo or Mus), models (in vitro or in vivo), microgravity conditions (real microgravity or ground-based simulators) and microgravity duration showed that it is difficult to reach a consistent conclusion about the pathogenesis of microgravity-induced bone loss across these studies. Even so, we identified 11 hub genes and some miRNA-mRNA interactions mainly based on the GSE100930 dataset. Also, the expression of CCL2, ICAM1, IGF1, miR-101-3p and miR-451a markedly changed under clinorotation-microgravity condition. Remarkedly, ICAM1 and miR-451a were key mediators of the osteogenesis of hMSCs under clinorotation-microgravity condition. These findings provide novel insights into the molecular mechanisms of bone loss during microgravity and could indicate potential targets for further countermeasures against this condition.

Low-intensity pulsed ultrasound/nanomechanical force generators enhance osteogenesis of BMSCs through microfilaments and TRPM7

BACKGROUND

Low-intensity pulsed ultrasound (LIPUS) has been reported to accelerate fracture healing, but the mechanism is unclear and its efficacy needs to be further optimized. Ultrasound in combination with functionalized microbubbles has been shown to induce local shear forces and controllable mechanical stress in cells, amplifying the mechanical effects of LIPUS. Nanoscale lipid bubbles (nanobubbles) have high stability and good biosafety. However, the effect of LIPUS combined with functionalized nanobubbles on osteogenesis has rarely been studied.

RESULTS

In this study, we report cyclic arginine-glycine-aspartic acid-modified nanobubbles (cRGD-NBs), with a particle size of ~ 500 nm, able to actively target bone marrow mesenchymal stem cells (BMSCs) via integrin receptors. cRGD-NBs can act as nanomechanical force generators on the cell membrane, and further enhance the BMSCs osteogenesis and bone formation promoted by LIPUS. The polymerization of actin microfilaments and the mechanosensitive transient receptor potential melastatin 7 (TRPM7) ion channel play important roles in BMSCs osteogenesis promoted by LIPUS/cRGD-NBs. Moreover, the mutual regulation of TRPM7 and actin microfilaments promote the effect of LIPUS/cRGD-NBs. The extracellular Ca^2 + influx, controlled partly by TRPM7, could participated in the effect of LIPUS/cRGD-NBs on BMSCs.

CONCLUSIONS

The nanomechanical force generators cRGD-NBs could promote osteogenesis of BMSCs and bone formation induced by LIPUS, through regulation TRPM7, actin cytoskeleton, and intracellular calcium oscillations. This study provides new directions for optimizing the efficacy of LIPUS for fracture healing, and a theoretical basis for the further application and development of LIPUS in clinical practice.

lncRNA SNHG1 regulates odontogenic differentiation of human dental pulp stem cells via miR-328-3p/Wnt/β-catenin pathway

Background

Elucidating the mechanism of odontogenic differentiation of human dental pulp stem cells (hDPSCs) is the key to in-depth mastery and development of regenerative endodontic procedures (REPs). In odontogenic differentiation, lncRNAs have a regulatory role. The goal of this research is to determine the involvement of short nucleolar RNA host gene 1 (SNHG1) in hDPSCs’ odontogenic differentiation and the mechanism that underpins it.

Methods

hDPSCs were isolated from the dental pulp tissue of healthy immature permanent teeth. Follow-up experiments were performed when the third generation of primary cells were transfected. The proliferation ability was measured by CCK-8. The biological effects of SNHG1 and miR-328-3p were determined by real-time quantitative polymerase chain reaction (qRT-PCR), western blot (WB), alkaline phosphatase (ALP) staining and activity, alizarin red S staining (ARS) and quantification, and immunofluorescence staining. The binding of SNHG1 and miR-328-3p was confirmed using a dual-luciferase reporter assay. qRT-PCR and WB were used to determine whether the canonical Wnt/β-catenin pathway was activated.

Results

On the 0th, 3rd, and 7th days of odontogenic differentiation of hDPSCs, SNHG1 showed a gradual up-regulation trend. SNHG1 overexpression enhanced the mRNA and protein expression of dentin sialophosphoprotein (DSPP), dentine matrix protein 1 (DMP-1) and ALP. We found that SNHG1 could bind to miR-328-3p. miR-328-3p inhibited the odontogenic differentiation of hDPSCs. Therefore, miR-328-3p mimics rescued the effect of SNHG1 overexpression on promoting odontogenic differentiation. In addition, SNHG1 inhibited Wnt/β-catenin pathway via miR-328-3p in odontogenic differentiation of hDPSCs.

Conclusion

lncRNA SNHG1 inhibits Wnt/β-catenin pathway through miR-328-3p and then promotes the odontogenic differentiation of hDPSCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02979-w.

The Emerging Role of Non-Coding RNAs in Osteogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells

Autologous bone marrow-derived mesenchymal stem cells (BMSCs) are more easily available and frequently used for bone regeneration in clinics. Osteogenic differentiation of BMSCs involves complex regulatory networks affecting bone formation phenomena. Non-coding RNAs (ncRNAs) refer to RNAs that do not encode proteins, mainly including microRNAs, long non-coding RNAs, circular RNAs, piwi-interacting RNAs, transfer RNA-derived small RNAs, etc. Recent in vitro and in vivo studies had revealed the regulatory role of ncRNAs in osteogenic differentiation of BMSCs. NcRNAs had both stimulatory and inhibitory effects on osteogenic differentiation of BMSCs. During the physiological condition, osteo-stimulatory ncRNAs are upregulated and osteo-inhibitory ncRNAs are downregulated. The opposite effects might occur during bone degenerative disease conditions. Intracellular ncRNAs and ncRNAs from neighboring cells delivered via exosomes participate in the regulatory process of osteogenic differentiation of BMSCs. In this review, we summarize the recent advances in the regulatory role of ncRNAs on osteogenic differentiation of BMSCs during physiological and pathological conditions. We also discuss the prospects of the application of modulation of ncRNAs function in BMSCs to promote bone tissue regeneration in clinics.

Evaluating the Role of lncRNAs in the Incidence of Cardiovascular Diseases in Androgenetic Alopecia Patients

Hair loss occurs in patients with Androgenetic Alopecia (AGA). The pattern of hair loss is different between men and women. The main cause of hair loss is increased cell apoptosis and decreased regeneration, proliferation and differentiation processes in hair follicles. Long Non-Coding RNAs (lncRNAs) are one of the most important molecules that regulate the processes of apoptosis, regeneration, proliferation and differentiation in hair follicles. Since studies have shown that lncRNAs can be effective in the development of cardiotoxicity and induction of cardiovascular disease (CVD); so effective lncRNAs in the regulation of regeneration, proliferation, differentiation and apoptosis of hair follicles can be involved in the development of CVD in AGA patients with. Therefore, this study investigated the lncRNAs involved in increasing apoptosis and reducing the processes of regeneration, proliferation and differentiation of hair follicles. The aim of the current study was to evaluate the role of lncRNAs as a risk factor in the incidence of CVD in AGA patients; it will help to design treatment strategies by targeting signaling pathways without any cardiotoxicity complications.

Drug Discovery of DKK1 Inhibitors

Dickkopf-1 (DKK1) is a well-characterized Wnt inhibitor and component of the Wnt/β-catenin signaling pathway, whose dysregulation is associated with multiple abnormal pathologies including osteoporosis, Alzheimer's disease, diabetes, and various cancers. The Wnt signaling pathway has fundamental roles in cell fate determination, cell proliferation, and survival; thus, its mis-regulation can lead to disease. Although DKK1 is involved in other signaling pathways, including the β-catenin-independent Wnt pathway and the DKK1/CKAP4 pathway, the inhibition of DKK1 to propagate Wnt/β-catenin signals has been validated as an effective way to treat related diseases. In fact, strategies for developing DKK1 inhibitors have produced encouraging clinical results in different pathological models, and many publications provide detailed information about these inhibitors, which include small molecules, antibodies, and nucleic acids, and may function at the protein or mRNA level. However, no systematic review has yet provided an overview of the various aspects of their development and prospects. Therefore, we review the DKK1 inhibitors currently available or under study and provide an outlook on future studies involving DKK1 and drug discovery.

[Regulation of long non-coding RNA in signal pathways related to osteogenic differentiation]

OBJECTIVE

To summarize the mechanism of long non-coding RNA (lncRNA) in signal pathways related to osteogenic differentiation.

METHODS

Relevant domestic and foreign researches in recent years were consulted. The characteristics and biological functions of lncRNA were introduced, and the specific mechanism of lncRNA regulating related signal pathways in osteogenic differentiation was elaborated.

RESULTS

The exertion and maintenance of normal function of bone requires the closed coordination of transcription networks and signal pathways. However, most of these signal pathways or networks are dysregulated under pathological conditions that affect bone homeostasis. lncRNA can regulate the differentiation of various bone cells by activating or inhibiting signal pathways to achieve the balance of bone homeostasis, thereby reversing the pathological state of bones and achieving the purpose of treating bone metabolic diseases.

CONCLUSION

At present, the research on the mechanism of lncRNA regulating various osteogenic differentiation pathways is still in the early stage. Its in-depth regulator mechanism, especially the cross-talk of complex signal pathways needs to be further studied. And how to apply these molecular targets to clinical treatment is also a big challenge.

A Quartet Network Analysis Identifying Mechanically Responsive Long Noncoding RNAs in Bone Remodeling

Mechanical force, being so ubiquitous that it is often taken for granted and overlooked, is now gaining the spotlight for reams of evidence corroborating their crucial roles in the living body. The bone, particularly, experiences manifold extraneous force like strain and compression, as well as intrinsic cues like fluid shear stress and physical properties of the microenvironment. Though sparkled in diversified background, long noncoding RNAs (lncRNAs) concerning the mechanotransduction process that bone undergoes are not yet detailed in a systematic way. Our principal goal in this research is to highlight the potential lncRNA-focused mechanical signaling systems which may be adapted by bone-related cells for biophysical environment response. Based on credible lists of force-sensitive mRNAs and miRNAs, we constructed a force-responsive competing endogenous RNA network for lncRNA identification. To elucidate the underlying mechanism, we then illustrated the possible crosstalk between lncRNAs and mRNAs as well as transcriptional factors and mapped lncRNAs to known signaling pathways involved in bone remodeling and mechanotransduction. Last, we developed combinative analysis between predicted and established lncRNAs, constructing a pathway–lncRNA network which suggests interactive relationships and new roles of known factors such as H19. In conclusion, our work provided a systematic quartet network analysis, uncovered candidate force-related lncRNAs, and highlighted both the upstream and downstream processes that are possibly involved. A new mode of bioinformatic analysis integrating sequencing data, literature retrieval, and computational algorithm was also introduced. Hopefully, our work would provide a moment of clarity against the multiplicity and complexity of the lncRNA world confronting mechanical input.

M2 macrophagy-derived exosomal miRNA-26a-5p induces osteogenic differentiation of bone mesenchymal stem cells

BACKGROUND

Bone marrow mesenchymal stem cells have always been a heated research topic in bone tissue regeneration and repair because of their self-renewal and multi-differentiation potential. A large number of studies have been focused on finding the inducing factors that will promote the osteogenic differentiation of bone marrow mesenchymal stem cells. Previous studies have shown that macrophage exosomes or miRNA-26a-5p can make it work, but the function of this kind of substance on cell osteogenic differentiation has not been public.

METHODS

M2 macrophages are obtained from IL-4 polarized bone marrow-derived macrophages. Exosomes were isolated from the supernatant of M2 macrophages and identified via transmission electron microscopy (TEM), western blotting, and DLS. Chondrogenic differentiation potential was detected by Alcian blue staining. Oil red O staining was used to detect the potential for lipogenic differentiation. And MTT would detect the proliferative capacity of cells. Western blot was performed to detect differential expression of osteogenic differentiation-related proteins.

RESULTS

The results showed that M2 macrophage exosomes will promote bone differentiation and at the same time inhibit lipid differentiation. In addition, M2 macrophage-derived exosomes have the function of promoting the expression of SOX and Aggrecan suppressing the level of MMP13. The exosome inhibitor GW4689 suppresses miRNA-26a-5p in M2 macrophage exosomes, and the treated exosomes do not play an important role in promoting bone differentiation. Moreover, miRNA-26a-5p can enable to promote bone differentiation and inhibit lipid differentiation. miRNA-26a-5p can promote the expression of ALP (alkaline phosphatase), RUNX-2 (Runt-related transcription factor 2), OPN(osteopontin), and Col-2(collagen type II). Therefore, it is speculated that exosomal miRNA-26a-5p is indispensable in osteogenic differentiation.

CONCLUSIONS

The present study indicated that M2 macrophage exosomes carrying miRNA-26a-5p can induce osteogenic differentiation of bone marrow-derived stem cells to inhibit lipogenic differentiation, and miRNA-26a-5p will also promote the expression of osteogenic differentiation-related proteins ALP, RUNX-2, OPN, and Col-2.

Long noncoding RNA SNHG1 silencing accelerates hepatocyte-like cell differentiation of bone marrow-derived mesenchymal stem cells to alleviate cirrhosis via the microRNA-15a/SMURF1/UVRAG axis

Bone marrow-derived mesenchymal stem cells (BMSCs) can differentiate into hepatocyte-like cells (HLCs) to attenuate cirrhosis. Long noncoding RNA (lncRNA) SNHG1 has been demonstrated to orchestrate BMSC differentiation, whereas its role in cirrhosis remains elusive. Therefore, this study was performed to figure out whether lncRNA SNHG1 was involved in cirrhosis by affecting HLC differentiation of BMSCs. Mouse BMSCs were isolated, and the BMSC differentiation into HLCs was induced by hepatocyte growth factor (HGF). A cirrhotic mouse model was established using carbon tetrachloride and phenobarbital, followed by intravenous injection of BMSCs with manipulated expression of lncRNA SNHG1, microRNA (miR)-15a, and SMURF1. Subsequent to HGF induction, expression of hepatocyte-related genes, albumin secretion, and glycogen accumulation was increased in BMSCs, suggesting the differentiation of BMSCs into HLCs. Mechanistically, lncRNA SNHG1 bound to miR-15a that targeted SMURF1, and SMURF1 diminished ATG5 and Wnt5a expression by enhancing the ubiquitination of UVRAG. LncRNA SNHG1 or SMURF1 silencing or miR-15a overexpression promoted differentiation of BMSCs into HLCs and repressed cirrhosis of mice by upregulating ATG5 and Wnt5a via UVRAG. Conclusively, lncRNA SNHG1 silencing might facilitate HLC differentiation from mouse BMSCs and alleviate cirrhosis via the miR-15a/SMURF1/UVRAG/ATG5/Wnt5a axis.

Long non-coding RNA GAS5 inhibits osteogenic differentiation through miR-382-3p/TAF1 signaling

Background: Long non-coding RNAs (lncRNAs) have been confirmed as important regulators during osteogenic differentiation. Previous researches have disclosed that growth arrest-specific transcript 5 (GAS5) can promote the osteogenic differentiation of human bone marrow mesenchyml stem cells (hBMSCs), but the underlying regulatory mechanism of GAS5 during the osteogenic differentiation of hBMSCs is unclear. Methods: Osteogenic differentiation was induced in hBMSCs by using osteogenic medium (OM). Gene expression was assessed by RT-qPCR or western blot assays as needed. ALP activity, ALP staining and ARS staining assays were performed to evaluate the impact of GAS5, microRNA-382-3p (miR-382-3p) and TATA-box binding protein associated factor 1 (TAF1) on osteogenic differentiation in vitro. The interaction among GAS5, miR-382-3p and TAF1 was determined by RIP, ChIP and luciferase reporter assays. Results: Expression of GAS5 (transcript variant 2) was down-regulated during the osteogenic differentiation of hBMSCs and its overexpression retarded the osteogenic differentiation of hBMSCs. GAS5 inhibited miR-382-3p through targeting RNA-directed microRNA degradation (TDMD). MiR-382-3p down-regulation partially offset the promoted osteogenic differentiation of hBMSCs upon GAS5 silencing. TAF1 negatively modulated osteogenic differentiation and it activated GAS5 transcription so as to form a positive GAS5/miR-382-3p/TAF1 feedback loop in hBMSCs. Conclusion: This research was the first to reveal that the GAS5/miR-382-3p/TAF1 feedback loop inhibited the osteogenic differentiation of hBMSCs, which provided new clues for exploring the mechanism of osteogenic differentiation and disclosed the potential of GAS5 as a promising target during osteogenic differentiation.

lncRNA SNHG1 induced by SP1 regulates bone remodeling and angiogenesis via sponging miR-181c-5p and modulating SFRP1/Wnt signaling pathway

BACKGROUND

We aimed to investigate the functions and underlying mechanism of lncRNA SNHG1 in bone differentiation and angiogenesis in the development of osteoporosis.

METHODS

The differential gene or proteins expressions were measured by qPCR or western blot assays, respectively. The targeted relationships among molecular were confirmed through luciferase reporter, RIP and ChIP assays, respectively. Alkaline phosphatase (ALP), alizarin red S (ARS) and TRAP staining were performed to measure the osteoblast/osteoclast differentiation of BMSCs. The viability, migration and angiogenesis in BM-EPCs were validated by CCK-8, clone formation, transwell and tube formation assays, respectively. Western blot and immunofluorescence detected the cytosolic/nuclear localization of β-catenin. Ovariectomized (OVX) mice were established to confirm the findings in vitro.

RESULTS

SNHG1 was enhanced and miR-181c-5p was decreased in serum and femoral tissue from OVX mice. SNHG1 directly inhibited miR-181c-5p to activate Wnt3a/β-catenin signaling by upregulating SFRP1. In addition, knockdown of SNHG1 promoted the osteogenic differentiation of BMSCs by increasing miR-181c-5p. In contrast, SNHG1 overexpression advanced the osteoclast differentiation of BMSCs and inhibited the angiogenesis of BM-EPCs, whereas these effects were all reversed by miR-181c-5p overexpression. In vivo experiments indicated that SNHG1 silencing alleviated osteoporosis through stimulating osteoblastogenesis and inhibiting osteoclastogenesis by modulating miR-181c-5p. Importantly, SNHG1 could be induced by SP1 in BMSCs.

CONCLUSIONS

Collectively, SP1-induced SNHG1 modulated SFRP1/Wnt/β-catenin signaling pathway via sponging miR-181c-5p, thereby inhibiting osteoblast differentiation and angiogenesis while promoting osteoclast formation. Further, SNHG1 silence might provide a potential treatment for osteoporosis.

Perspectives on miRNAs Targeting DKK1 for Developing Hair Regeneration Therapy

Androgenetic alopecia (AGA) remains an unsolved problem for the well-being of humankind, although multiple important involvements in hair growth have been discovered. Up until now, there is no ideal therapy in clinical practice in terms of efficacy and safety. Ultimately, there is a strong need for developing a feasible remedy for preventing and treating AGA. The Wnt/β-catenin signaling pathway is critical in hair restoration. Thus, AGA treatment via modulating this pathway is rational, although challenging. Dickkopf-related protein 1 (DKK1) is distinctly identified as an inhibitor of canonical Wnt/β-catenin signaling. Thus, in order to stimulate the Wnt/β-catenin signaling pathway, inhibition of DKK1 is greatly demanding. Studying DKK1-targeting microRNAs (miRNAs) involved in the Wnt/β-catenin signaling pathway may lay the groundwork for the promotion of hair growth. Bearing in mind that DKK1 inhibition in the balding scalp of AGA certainly makes sense, this review sheds light on the perspectives of miRNA-mediated hair growth for treating AGA via regulating DKK1 and, eventually, modulating Wnt/β-catenin signaling. Consequently, certain miRNAs regulating the Wnt/β-catenin signaling pathway via DKK1 inhibition might represent attractive candidates for further studies focusing on promoting hair growth and AGA therapy.

Long non-coding RNA RP11-84C13.1 promotes osteogenic differentiation of bone mesenchymal stem cells and alleviates osteoporosis progression via the miR-23b-3p/RUNX2 axis

The objective of the present study was to determine the role of RP11-84C13.1 in osteoporosis (OP) and its molecular mechanism. First, clinical samples were collected from OP patients and normal control patients. Human bone marrow stromal cells (hBMSCs) were extracted from femoral head tissues. Runt-related transcription factor 2 (RUNX2) and RP11-84C13.1 serum levels were assessed by reverse transcription-quantitative (RT-q)PCR. Following transfection of pcDNA-RP11-84C13.1, si-RP11-84C13.1, microRNA (miRNA)-23b-3p mimic and miRNA-23b-3p inhibitor, the expression levels of RUNX2 and RP11-84C13.1 were determined by RT-qPCR. In addition, the osteogenic ability of hBMSCs was assessed by Alizarin Red staining. The binding of RP11-84C13.1 to miRNA-23b-3p and the binding of miRNA-23b-3p to RUNX2 was confirmed by dual-luciferase reporter gene assay. Long non-coding RNA (lncRNA) RP11-84C13.1 was significantly downregulated in the serum of OP patients. The osteogenic differentiation-related genes RUNX2 and RP11-84C13.1 were markedly upregulated in a time-dependent manner, while the miRNA-23b-3p level gradually decreased in hBMSCs with the prolongation of osteogenesis. RP11-84C13.1 knockdown inhibited the osteogenic differentiation of hBMSCs. Furthermore, RP11-84C13.1 regulated RUNX2 expression by targeting miRNA-23b-3p. Overexpression of miRNA-23b-3p partially reversed the promoting effect of RP11-84C13.1 on the osteogenesis of hBMSCs. In conclusion, lncRNA RP11-84C13.1 upregulated RUNX2 by absorbing miRNA-23b-3p, and thus induced hBMSC osteogenesis to alleviate osteoporosis.

Long non-coding RNA potassium voltage-gated channel subfamily Q member 1 overlapping transcript 1 regulates the proliferation and osteogenic differentiation of human periodontal ligament stem cells by targeting miR-24-3p

OBJECTIVES

This study aims to explore the effect and molecular mechanism of long non-coding RNA (lncRNA) potassium voltage-gated channel subfamily Q member 1 overlapping transcript 1 (KCNQ1OT1) on proliferation and osteogenic differentiation in human periodontal ligament stem cells (hPDLSCs).

METHODS

The hPDLSCs of normal periodontal tissues were isolated and cultured. The mineralized solution induced the osteoblast differentiation of hPDLSCs. The down-regulation of lncRNA KCNQ1OT1, the overexpression of anti-miR-24-3p on the proliferation and the levels of osteocalcin (OCN), osteopontin (OPN) and alkaline phosphatase (ALP) of hPDLSCs were investigated. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the levels of lncRNA KCNQ1OT1, miR-24-3p, OCN, OPN, and ALP. Methyl thiazolyl tetrazolium (MTT) method was used to detect cell viability and activity. Cell proliferation was evaluated by MTT. Western blot was used to detect protein expression. The targeted relationship between lncRNA KCNQ1OT1 and miR-24-3p was detected by double-luciferase experiment.

RESULTS

The expression level of lncRNA KCNQ1OT1 increased, and that of miR-24-3p decreased during the osteogenesis of hPDLSCs (P<0.05). The down-regulation of lncRNA KCNQ1OT1 inhibited cell proliferation and reduced the mRNA and protein expression levels of OCN, OPN, and ALP (P<0.05). LncRNA KCNQ1OT1 targeted and regulated miR-24-3p. The overexpression of miR-24-3p inhibited cell proliferation and reduced the mRNA and protein expression levels of OCN, OPN, and ALP (P<0.05). Inhibition of miR-24-3p reversed the effect of the down-regulation of lncRNA KCNQ1OT1 on cell proliferation and mRNA and protein expression levels of OCN, OPN, and ALP (P<0.05).

CONCLUSIONS

Down-regulation of lncRNA KCNQ1OT1 inhibited the proliferation and osteogenic differentiation of hPDLSCs by targeting the up-regulated expression of miR-24-3p.

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.

miR-1249-5p regulates the osteogenic differentiation of ADSCs by targeting PDX1

Background

Osteoporosis (OP) is an age-related systemic bone disease. MicroRNAs (miRNAs) are involved in the regulation of osteogenic differentiation. The purpose of this study was to explore the role and mechanism of miR-1249-5p for promoting osteogenic differentiation of adipose-derived stem cells (ADSCs).

Methods

GSE74209 dataset was retrieved from NCBI Gene Expression Omnibus (GEO) database and performed bioinformatic analyses. OP tissue and healthy control tissues were obtained and used for RT-PCR analyses. ADSCs were incubated with miR-1249-5p mimic, inhibitor and corresponding negative control (NC), alkaline phosphatase (ALP) staining, and Alizarin Red Staining (ARS) were then performed to assess the role of miR-1249-5p for osteogenesis of ADSCs. Targetscan online website and dual-luciferase reporter assay were performed to verify that the 3′-UTR of PDX1 mRNA is a direct target of miR-1249-5p. RT-PCR and western blot were also performed to identify the mechanism of miR-1249-5p for osteogenesis of ADSCs.

Results

A total of 170 differentially expressed miRNAs were selected, among which, 75 miRNAs were downregulated and 95 miRNAs were upregulated. Moreover, miR-1249-5p was decreased in OP patients, while showed a gradual increase with the extension of induction time. miR-1249-5p mimic significantly increased osteogenic differentiation capacity and p-PI3K and p-Akt protein levels. Luciferase activity in ADSCs co-transfected of miR-1249-5p mimic with PDX1-WT reporter plasmids was remarkably decreased, but there was no obvious change in miR-1249-5p mimic with PDX1-MUT reporter plasmids co-transfection group. Overexpression PDX1 could partially reverse the promotion effects of miR-1249-5p on osteogenesis of ADSCs.

Conclusion

In conclusion, miR-1249-5p promotes osteogenic differentiation of ADSCs by targeting PDX1 through the PI3K/Akt signaling pathway.

Silencing of miR-138-5p sensitizes bone anabolic action to mechanical stimuli

Emerging evidence is revealing that microRNAs (miRNAs) play essential roles in mechanosensing for regulating osteogenesis. However, no mechanoresponsive miRNAs have been identified in human bone specimens.

Methods: Bedridden and aged patients, hindlimb unloaded and aged mice, and Random Positioning Machine and primary aged osteoblasts were adopted to simulate mechanical unloading conditions at the human, animal and cellular levels, respectively. Treadmill exercise and Flexcell cyclic mechanical stretching were used to simulate mechanical loading in vivo and in vitro, respectively.

Results: Here, we found increased miR-138-5p levels with a lower degree of bone formation in bone specimens from bedridden and aged patients. Loss- and gain-of-function studies showed that miR-138-5p directly targeted microtubule actin crosslinking factor 1 (MACF1) to inhibit osteoblast differentiation under different mechanical conditions. Regarding translational medicine, bone-targeted inhibition of miR-138-5p attenuated the decrease in the mechanical bone anabolic response in hindlimb unloaded mice. Moreover, bone-targeted inhibition of miR-138-5p sensitized the bone anabolic response to mechanical loading in both miR-138-5p transgenic mice and aged mice to promote bone formation.

Conclusion: These data suggest that miR-138-5p as a mechanoresponsive miRNA accounts for the mechanosensitivity of the bone anabolic response and that inhibition of miR-138-5p in osteoblasts may be a novel bone anabolic sensitization strategy for ameliorating disuse or senile osteoporosis.