DLX3 promotes bone marrow mesenchymal stem cell proliferation through H19/miR-675 axis

LncRNA H19 promotes osteoclast differentiation by sponging miR-29c-3p to increase expression of cathepsin K

BACKGROUND

Osteoporosis is a prevalent metabolic bone disease. Osteoporotic fractures can lead to severe functional impairment and increased mortality. Long noncoding RNA H19 has emerged as a pivotal player in bone remodeling, serving both as a biomarker and a regulator. While previous research has elucidated H19's role in promoting osteogenic differentiation through diverse mechanisms, its involvement in osteoclast differentiation remains largely unknown.

METHODS

In this study, we used lentiviral vectors to stably overexpress or knockdown H19 in RAW264.7 cell lines. Quantitative reverse polymerase chain reaction, Western blot, tartrate resistant acid phosphatase staining and bone resorption assay were performed to assess the level of osteoclast differentiation and bone resorption capacity. And fluorescence in situ hybridization, dual-luciferase reporter and RNA immunoprecipitation were used to explore the specific mechanism of H19 regulating osteoclast differentiation in vitro. Then, ovariectomized osteoporosis models in wild type mice and H19 knockout mice were conducted. And micro-CT analysis, HE staining, and immunohistochemistry were performed to verify the mechanism of H19 regulating osteoclast differentiation in vivo. Bone marrow derived monocytes and bone mesenchymal stem cells were extracted from mice and assayed for osteoclastic and osteogenic-related assays, respectively.

RESULTS

In vitro, H19 promoted osteoclast differentiation and bone resorption of RAW264.7 cells, while miR-29c-3p inhibited them. Both H19 and cathepsin K were the target genes of miR-29c-3p. In vivo, H19 knockout mice have increased femur bone mineral density, decreased osteoclast formation, and reduced cathepsin K expression. MiR-29c-3p agomir could increase bone mineral density in osteoporotic mice on the premise of H19 knockout.

CONCLUSIONS

H19 upregulates cathepsin K expression through sponging miR-29c-3p, which promoting osteoclast differentiation and enhancing bone resorption. This underscores the potential of H19 and miR-29c-3p as promising biomarkers for osteoporosis.

The odontoblastic differentiation of dental mesenchymal stem cells: molecular regulation mechanism and related genetic syndromes

Dental mesenchymal stem cells (DMSCs) are multipotent progenitor cells that can differentiate into multiple lineages including odontoblasts, osteoblasts, chondrocytes, neural cells, myocytes, cardiomyocytes, adipocytes, endothelial cells, melanocytes, and hepatocytes. Odontoblastic differentiation of DMSCs is pivotal in dentinogenesis, a delicate and dynamic process regulated at the molecular level by signaling pathways, transcription factors, and posttranscriptional and epigenetic regulation. Mutations or dysregulation of related genes may contribute to genetic diseases with dentin defects caused by impaired odontoblastic differentiation, including tricho-dento-osseous (TDO) syndrome, X-linked hypophosphatemic rickets (XLH), Raine syndrome (RS), hypophosphatasia (HPP), Schimke immuno-osseous dysplasia (SIOD), and Elsahy-Waters syndrome (EWS). Herein, recent progress in the molecular regulation of the odontoblastic differentiation of DMSCs is summarized. In addition, genetic syndromes associated with disorders of odontoblastic differentiation of DMSCs are discussed. An improved understanding of the molecular regulation and related genetic syndromes may help clinicians better understand the etiology and pathogenesis of dentin lesions in systematic diseases and identify novel treatment targets.

miR-9-5p promotes myogenic differentiation via the Dlx3/Myf5 axis

MicroRNAs play an important role in myogenic differentiation, they bind to target genes and regulate muscle formation. We previously found that miR-9-5p, which is related to bone formation, was increased over time during the process of myogenic differentiation. However, the mechanism by which miR-9-5p regulates myogenic differentiation remains largely unknown. In the present study, we first examined myotube formation and miR-9-5p, myogenesis-related genes including Dlx3, Myod1, Mef2c, Desmin, MyoG and Myf5 expression under myogenic induction. Then, we detected the expression of myogenic transcription factors after overexpression or knockdown of miR-9-5p or Dlx3 in the mouse premyoblast cell line C2C12 by qPCR, western blot and myotube formation under myogenic induction. A luciferase assay was performed to confirm the regulatory relationships between not only miR-9-5p and Dlx3 but also Dlx3 and its downstream gene, Myf5, which is an essential transcription factor of myogenic differentiation. The results showed that miR-9-5p promoted myogenic differentiation by increasing myogenic transcription factor expression and promoting myotube formation, but Dlx3 exerted the opposite effect. Moreover, the luciferase assay showed that miR-9-5p bound to the 3'UTR of Dlx3 and downregulated Dlx3 expression. Dlx3 in turn suppressed Myf5 expression by binding to the Myf5 promoter, ultimately inhibiting the process of myogenic differentiation. In conclusion, the miR-9-5p/Dlx3/Myf5 axis is a novel pathway for the regulation of myogenic differentiation, and can be a potential target to treat the diseases related to muscle dysfunction.

The crucial role of model systems in understanding the complexity of cell signaling in human neurocristopathies

Animal models are useful to study the molecular, cellular, and morphogenetic mechanisms underlying normal and pathological development. Cell-based study models have emerged as an alternative approach to study many aspects of human embryonic development and disease. The neural crest (NC) is a transient, multipotent, and migratory embryonic cell population that generates a diverse group of cell types that arises during vertebrate development. The abnormal formation or development of the NC results in neurocristopathies (NCPs), which are characterized by a broad spectrum of functional and morphological alterations. The impaired molecular mechanisms that give rise to these multiphenotypic diseases are not entirely clear yet. This fact, added to the high incidence of these disorders in the newborn population, has led to the development of systematic approaches for their understanding. In this article, we have systematically reviewed the ways in which experimentation with different animal and cell model systems has improved our knowledge of NCPs, and how these advances might contribute to the development of better diagnostic and therapeutic tools for the treatment of these pathologies. This article is categorized under: Congenital Diseases > Genetics/Genomics/Epigenetics Congenital Diseases > Stem Cells and Development Congenital Diseases > Molecular and Cellular Physiology Neurological Diseases > Genetics/Genomics/Epigenetics.

Effects of exercise on the expression of long non-coding RNAs in the bone of mice with osteoporosis

Physical activity or exercise are known to promote bone formation and decrease bone resorption to maintain skeletal and bone health both in animal models and in humans with osteoporosis. Previous studies have indicated that long non-coding RNAs (lncRNAs) are able to regulate bone metabolism. Therefore, the present study aimed to evaluate whether lncRNAs responded to exercise by regulating the balance of bone metabolism in order to prevent osteoporosis. To meet this end, ovariectomized mice were used in the present study to establish an osteoporosis model. The exercise treatment groups were subjected to 9 weeks of treadmill running exercise in 4 weeks of the operation was performed Femurs were collected to measure bone mineral density, bone mass, bone formation and resorption. The expression levels of lncRNAs were subsequently measured using microarray and gene function analyses. The pairwise comparison results [ovariectomy (OVX) vs. OVX + exercise (EX); OVX vs. SHAM; SHAM vs. SHAM + EX; OVX + EX vs. SHAM + EX] of the gene microarray analysis revealed that the expression of 2,424 lncRNAs (1718 upregulated and 706 downregulated) were significantly altered in the mouse femurs following treadmill running. Gene Ontology (GO) analysis, incorporating the GO annotations ‘biological processes’, ‘molecular function’ and ‘cellular components’, of osteoporosis revealed that the VEGF, mTOR and NF-κB signaling pathways were potential targets of the lncRNAs. Moreover, it was possible to predict the target microRNAs (miRNAs) of six lncRNAs (LOC105246953, LOC102637959, NONMMUT014677, NONMMUT027251, ri|D130079K21|PX00187K16|1491 and NONMMUT006626), which suggested that the underlying mechanism by which lncRNAs respond to exercise involved bone regulation via lncRNA-miRNA sponge adsorption. Overall, these results suggested that the treadmill running exercise did regulate lncRNA expression in the bone, and that this was involved in the prevention of osteoporosis.

The role and mechanism of long non-coding RNA H19 in stem cell osteogenic differentiation

Background

In recent years, H19, as one of the most well-known long non-coding RNA, has been reported to play important roles in many biological and physiological processes. H19 has been identified to regulate the osteogenic differentiation of various stem cells in many studies. However, the detailed role and regulation mechanism of H19 was not consistent in the reported studies.

Main body of the manuscript

In this review article we summarized the effect and mechanism of lncRNA H19 on osteogenic differentiation of various stem cells reported in the published literatures. The role and mechanism of H19, H19 expression changes, effect of H19 on cell proliferation in osteogenic differentiation were respectively reviewed.

Conclusions

An increasing number of studies have provided evidence that H19 play its role in the regulation of stem cell osteogenic differentiation by different mechanisms. Most of the studies favored the positive regulatory effect of H19 through lncRNA-miRNA pathway. The function and underlying mechanisms by which H19 contributes to osteogenic differentiation require further investigation.

Graphene Oxide Quantum Dots Promote Osteogenic Differentiation of Stem Cells from Human Exfoliated Deciduous Teeth via the Wnt/β-Catenin Signaling Pathway

Graphene oxide quantum dots (GOQDs) are a carbon nanomaterial with broad potential for application in the field of nanomaterial biomedicine. Stem cells from human exfoliated deciduous teeth (SHEDs) play an important role in tissue engineering and regenerative medicine. This study investigated the effects of GOQDs on SHED osteogenic differentiation. GOQDs were synthesized; then, the proliferation of SHEDs incubated in GOQDs at different concentrations was evaluated; and the live cells were observed. We observed that live SHEDs incubated in GOQDs emitted green fluorescence in the absence of chemical dyes, and 1, 10, and 50 μg/mL GOQDs significantly promoted SHED proliferation. Culture with the osteogenic induction medium containing 10 μg/mL GOQDs induced calcium nodule formation, increased alkaline phosphatase (ALP) activity, and upregulated SHED mRNA and protein levels of OCN, RUNX2, COL I, and β-catenin. With the addition of Dickkopf 1 (DKK-1) or β-catenin knockdown, expression levels of the above mRNAs and proteins were decreased in GOQD-treated SHEDs. In summary, at a concentration of 10 μg/mL, GOQDs promote SHED proliferation and osteogenic differentiation via the Wnt/β-catenin signaling pathway. This work provides new ideas and fundamental information on interactions between GOQDs and SHEDs that are relevant for the biomedical engineering field.

Effects of DLX3 on the osteogenic differentiation of induced pluripotent stem cell‑derived mesenchymal stem cells

Osteoporosis is a disease characterized by the degeneration of bone structure and decreased bone mass. Induced pluripotent stem cell-derived mesenchymal stem cells (iPSC-MSCs) have multiple advantages that make them ideal seed cells for bone regeneration, including high-level proliferation, multi-differentiation potential and favorable immune compatibility. Distal-less homeobox (DLX)3, an important member of the DLX family, serves a crucial role in osteogenic differentiation and bone formation. The present study aimed to evaluate the effects of DLX3 on the proliferation and osteogenic differentiation of human iPSC-MSCs. iPSC-MSCs were induced from iPSCs, and identified via flow cytometry. Alkaline phosphatase (ALP), Von Kossa, Oil Red O and Alcian blue staining methods were used to evaluate the osteogenic, adipogenic and chondrogenic differentiation of iPSC-MSCs. DLX3 overexpression plasmids were constructed and transfected into iPSC-MSCs to generate iPSC-MSC-DLX3. iPSC-MSC-GFP was used as the control. Reverse transcription-quantitative PCR (RT-qPCR) and western blotting were performed to measure the expression of DLX3 2 days after transfection. Subsequently, cell proliferation was assessed using a Cell Counting Kit-8 assay on days 1, 3, 5 and 7. RT-qPCR and western blotting were used to analyze osteogenic-related gene and protein expression levels on day 7. ALP activity and mineralized nodules were assessed via ALP staining on day 14. Statistical analysis was performed using an unpaired Student's t-test. Flow cytometry results demonstrated that iPSC-MSCs were positive for CD73, CD90 and CD105, but negative for CD34 and CD45. iPSC-MSC-DLX3 had significantly lower proliferation compared with iPSC-MSC-GFP on days 5 and 7 (P<0.05). mRNA expression levels of osteogenic markers, such as ALP, osteopenia (OPN), osteocalcin (OCN) and Collagen Type I (COL-1), were significantly increased in iPSC-MSC-DLX3 compared with iPSC-MSC-GFP on day 7 (P<0.05). Similarly, the protein expression levels of ALP, OCN, OPN and COL-1 were significantly increased in iPSC-MSC-DLX3 compared with iPSC-MSC-GFP on day 7 (P<0.05). The number of mineralized nodules in iPSC-MSC-DLX3 was increased compared with that in iPSC-MSC-GFP on day 14 (P<0.05). Thus, the present study demonstrated that DLX3 serves a negative role in proliferation, but a positive role in the osteogenic differentiation of iPSC-MSCs. This may provide novel insight for treating osteoporosis.

The miR-4739/DLX3 Axis Modulates Bone Marrow-Derived Mesenchymal Stem Cell (BMSC) Osteogenesis Affecting Osteoporosis Progression

Osteoporosis is a complex multifactorial disorder linked to various risk factors and medical conditions. Bone marrow-derived mesenchymal stem cell (BMSC) dysfunction potentially plays a critical role in osteoporosis pathogenesis. Herein, the study identified that miR-4739 was upregulated in BMSC cultures harvested from osteoporotic subjects. BMSCs were isolated from normal and osteoporotic bone marrow tissues and identified for their osteogenic differentiation potential. In osteoporotic BMSCs, miR-4739 overexpression significantly inhibited cell viability, osteoblast differentiation, mineralized nodule formation, and heterotopic bone formation, whereas miR-4739 inhibition exerted opposite effects. Through direct binding, miR-4739 inhibited distal-less homeobox 3 (DLX3) expression. In osteoporotic BMSCs, DLX3 knockdown also inhibited BMSC viability and osteogenic differentiation. Moreover, DLX3 knockdown partially attenuated the effects of miR-4739 inhibition upon BMSCs. Altogether, the miR-4739/DLX3 axis modulates the capacity of BMSCs to differentiate into osteoblasts, which potentially plays a role in osteoporosis pathogenesis. The in vivo and clinical functions of the miR-4739/DLX3 axis require further investigation.

LncRNA, Important Player in Bone Development and Disease

BACKGROUND

Bone is an important tissue and its normal function requires tight coordination of transcriptional networks and signaling pathways, and many of these networks/ pathways are dysregulated in pathological conditions affecting cartilage and bones. Long non-coding RNA (lncRNA) refers to a class of RNAs with a length of more than 200 nucleotides, lack of protein-coding potential, and exhibiting a wide range of biological functions. Although studies on lcnRNAs are still in their infancy, they have emerged as critical players in bone biology and bone diseases. The functions and exact mechanism of bone-related lncRNAs have not been fully classified yet.

OBJECTIVE

The objective of this article is to summarize the current literature on lncRNAs on the basis of their role in bone biology and diseases, focusing on their emerging molecular mechanism, pathological implications and therapeutic potential.

DISCUSSION

A number of lncRNAs have been identified and shown to play important roles in multiple bone cells and bone disease. The function and mechanism of bone-related lncRNA remain to be elucidated.

CONCLUSION

At present, majority of knowledge is limited to cellular levels and less is known on how lncRNAs could potentially control the development and homeostasis of bone. In the present review, we highlight some lncRNAs in the field of bone biology and bone disease. We also delineate some lncRNAs that might have deep impacts on understanding bone diseases and providing new therapeutic strategies to treat these diseases.

The Emerging Roles of Long Noncoding RNAs in Bone Homeostasis and Their Potential Application in Bone-Related Diseases

Increasing evidence has announced the emerging roles of long noncoding RNAs (lncRNAs) in modulating bone homeostasis due to their potential regulating effects on bone-related cells' proliferation, migration, differentiation and apoptosis. Thus, lncRNAs have been considered as a promising gene tool to facilitate the bone regeneration process and then to predict and cure bone-related diseases such as osteosarcoma, osteoporosis, and osteoarthritis. In this review, we first enumerated several kinds of dysregulated lncRNAs and concisely summarized their regulating role in bone formation as well as resorption process. The related mechanisms were also discussed, respectively. Then, the positive or negative behavior of these lncRNAs in bone-related diseases was elucidated. This review provides an in-depth sight about the lncRNA's clinical values and limitations, which is conducive to explore new gene targets and further establish new therapeutic strategies for bone-related disease.

Stem cell therapy of myocardial infarction: a promising opportunity in bioengineering

Myocardial infarction (MI) is a life-threatening disease resulting from irreversible death of cardiomyocytes (CMs) and weakening of the heart blood-pumping function. Stem cell-based therapies have been studied for MI treatment over the last two decades with promising outcome. In this review, we critically summarize the past work in this field to elucidate the advantages and disadvantages of treating MI using pluripotent stem cells (PSCs) including both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), adult stem cells, and cardiac progenitor cells. The main advantage of the latter is their cytokine production capability to modulate immune responses and control the progression of healing. However, human adult stem cells have very limited (if not 'no') capacity to differentiate into functional CMs in vitro or in vivo. In contrast, PSCs can be differentiated into functional CMs although the protocols for the cardiac differentiation of PSCs are mainly for adherent cells under 2D culture. Derivation of PSC-CMs in 3D, allowing for large-scale production of CMs via modulation of the Wnt/β-catenin signal pathway with defined chemicals and medium, may be desired for clinical translation. Furthermore, the technology of purification and maturation of the PSC-CMs may need further improvements to eliminate teratoma formation after in vivo implantation of the PSC-CMs for treating MI. In addition, in vitro derived PSC-CMs may have mechanical and electrical mismatch with the patient's cardiac tissue, which causes arrhythmia. This supports the use of PSC-derived cells committed to cardiac lineage without beating for implantation to treat MI. In this case, the PSC derived cells may utilize the mechanical, electrical, and chemical cues in the heart to further differentiate into mature/functional CMs in situ. Another major challenge facing stem cell therapy of MI is the low retention/survival of stem cells or their derivatives (e.g., PSC-CMs) in the heart for MI treatment after injection in vivo. This may be resolved by using biomaterials to engineer stem cells for reduced immunogenicity, immobilization of the cells in the heart, and increased integration with the host cardiac tissue. Biomaterials have also been applied in the derivation of CMs in vitro to increase the efficiency and maturation of differentiation. Collectively, a lot has been learned from the past failure of simply injecting intact stem cells or their derivatives in vivo for treating MI, and bioengineering stem cells with biomaterials is expected to be a valuable strategy for advancing stem cell therapy towards its widespread application for treating MI in the clinic.

lncRNAs: function and mechanism in cartilage development, degeneration, and regeneration

With the increasing incidence of cartilage-related diseases such as osteoarthritis (OA) and intervertebral disc degeneration (IDD), heavier financial and social burdens need to be faced. Unfortunately, there is no satisfactory clinical method to target the pathophysiology of cartilage-related diseases. Many gene expressions, signaling pathways, and biomechanical dysregulations were involved in cartilage development, degeneration, and regeneration. However, the underlying mechanism was not clearly understood. Recently, lots of long non-coding RNAs (lncRNAs) were identified in the biological processes, including cartilage development, degeneration, and regeneration. It is clear that lncRNAs were important in regulating gene expression and maintaining chondrocyte phenotypes and homeostasis. In this review, we summarize the recent researches studying lncRNAs’ expression and function in cartilage development, degeneration, and regeneration and illustrate the potential mechanism of how they act in the pathologic process. With continued efforts, regulating lncRNA expression in the cartilage regeneration may be a promising biological treatment approach.

DLX3 regulates osteogenic differentiation of bone marrow mesenchymal stem cells via Wnt/β-catenin pathway mediated histone methylation of DKK4

OBJECTIVE

Distal-less homeobox 3 (DLX3) is an important transcription factor involved in the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). However, the underlying mechanism is not clear. This study investigated the underlying mechanism of DLX3 in osteogenic differentiation.

METHODS

DLX3 overexpression and knockdown in cells were achieved using lentiviruses. The osteogenic differentiation of BMSCs was detected using alkaline phosphatase expression, alizarin red staining, real-time quantitative polymerase chain reaction (RT-qPCR), Western blotting, and chromatin immunoprecipitation (ChIP) assays.

RESULTS

DLX3 overexpression promoted the osteogenic differentiation of BMSCs, whereas DLX3 knockdown reduced the osteogenic differentiation of BMSCs. RT-qPCR and Western blotting assays showed that DLX3 modulated osteogenic differentiation via the Wnt/β-catenin pathway. ChIP-qPCR showed that DLX3 knockdown promoted DKK4 expression by decreasing the enrichment of histone H3 lysine 27 trimethylation (H3K27me3) in the promotor region of DKK4.

CONCLUSION

Our data implied that DLX3 regulated Wnt/β-catenin pathway through histone modification of DKK4 during the osteogenic differentiation of BMSCs.

Long non-coding RNA in osteogenesis: A new world to be explored

Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides with limited coding potential, which have emerged as novel regulators in many biological and pathological processes, including growth, development, and oncogenesis. Accumulating evidence suggests that lncRNAs have a special role in the osteogenic differentiation of various types of cell, including stem cells from different sources such as embryo, bone marrow, adipose tissue and periodontal ligaments, and induced pluripotent stem cells. Involved in complex mechanisms, lncRNAs regulate osteogenic markers and key regulators and pathways in osteogenic differentiation. In this review, we provide insights into the functions and molecular mechanisms of lncRNAs in osteogenesis and highlight their emerging roles and clinical value in regenerative medicine and osteogenesis-related diseases.

Cite this article: J. Zhang, X. Hao, M. Yin, T. Xu, F. Guo. Long non-coding RNA in osteogenesis: A new world to be explored. Bone Joint Res 2019;8:73–80. DOI: 10.1302/2046-3758.82.BJR-2018-0074.R1.