HOXA10 inhibit the osteogenic differentiation of periodontal ligament stem cells by regulating β-catenin localization and DKK1 expression

Osteogenic differentiation of periodontal membrane stem cells in inflammatory environments

Periodontitis is a common disease that is difficult to treat, and if not controlled in time, it causes severe conditions, such as alveolar bone resorption and tooth loosening and loss. Periodontal ligament stem cells constitute a promising cell source for regenerative treatment of periodontitis due to their high osteogenic differentiation capacity. PDLSC osteogenesis plays a central role in periodontal regeneration through successive cytokine-mediated signaling pathways and various biochemical and physicochemical factors. However, this process is inhibited in the inflammatory periodontitis environment due to high concentrations of lipopolysaccharide. Here, we review the mechanisms that influence the osteogenic differentiation of periodontal stem cells in this inflammatory microenvironment.

mTOR is involved in LRP5-induced osteogenic differentiation of normal and aged periodontal ligament stem cells in vitro

Periodontal ligament stem cells (PDLSCs) plays an important role in tissue engineering. As the age increased, the cell viability and osteogenic differentiation of PDLSCs all decreased. Low density lipoprotein receptor related protein 5 (LRP5) was found to promote bone marrow mesenchymal stem cells osteogenic differentiation. Therefore, our study explored the effect of LRP5 on normal and aged PDLSCs and relative mechanism. Here, we found that the expression of LRP5 in PDLSCs of 24 week-old mice was decreased compared with PDLSCs of 5 week-old mice (n = 5). . LRP5 overexpression in PDLSCs increased the intensity of alkaline phosphatase and alizarin red staining, accompanied with upregulated the levels of RUNX family transcription factor 2, collagen type I, and β-Catenin. LRP5 knockdown displayed the opposite results in PDLSCs in vitro. LRP5 overexpression in aged PDLSCs restored part ability of osteogenic differentiation. Meantime, LRP5 increased the protein expression of phosphorylation of mammalian target of rapamycin (p-mTOR) in normal and aged PDLSCs. Immunofluorescence showed that LRP5 increased the accumulation of p-mTOR nucleus. The effect of LRP5 in promoting osteogenic differentiation of PDLSCs can be antagonized by mTOR inhibitor rapamycin. These findings suggest that LRP5 positively regulate osteogenic differentiation of normal and aged PDLSCs and may be a potential target for enlarging the application of PDLSCs in tissue regeneration.

Advances in periodontal stem cells and the regulating niche: From in vitro to in vivo

Periodontium possesses stem cell populations for its self-maintenance and regeneration, and has been proved to be an optimal stem cell source for tissue engineering. In vitro studies have shown that stem cells can be isolated from periodontal ligament, alveolar bone marrow and gingiva. In recent years, more studies have focused on identification of periodontal stem cells in vivo. Multiple genetic markers, including Gli1, Prx1, Axin2, αSMA, and LepR, were identified with the lineage tracing approaches. Characteristics, functions, and regulatory mechanisms of specific populations expressing one of these markers have been investigated. In vivo studies also revealed that periodontal stem cells can be regulafrted by different niche and mechanisms including intercellular interactions, ECM and multiple secreted factors. In this review, we summarized the current knowledge of in vitro characteristics and in vivo markers of periodontal stem cells, and discussed the specific regulating niche.

Application of exosome-derived noncoding RNAs in bone regeneration: Opportunities and challenges

With advances in the fields of regenerative medicine, cell-free therapy has received increased attention. Exosomes have a variety of endogenous properties that provide stability for molecular transport across biological barriers to cells, as a form of cell-to-cell communication that regulates function and phenotype. In addition, exosomes are an important component of paracrine signaling in stem-cell-based therapy and can be used as a stand-alone therapy or as a drug delivery system. The remarkable potential of exosomes has paved the pathway for cell-free treatment in bone regeneration. Exosomes are enriched in distinct noncoding RNAs (ncRNAs), including microRNAs, long ncRNAs and circular RNAs. Different ncRNAs have multiple functions. Altered expression of ncRNA in exosomes is associated with the regenerative potential and development of various diseases, such as femoral head osteonecrosis, myocardial infarction, and cancer. Although there is increasing evidence that exosome-derived ncRNAs (exo-ncRNAs) have the potential for bone regeneration, the detailed mechanisms are not fully understood. Here, we review the biogenesis of exo-ncRNA and the effects of ncRNAs on angiogenesis and osteoblast- and osteoclast-related pathways in different diseases. However, there are still many unsolved problems and challenges in the clinical application of ncRNA; for instance, production, storage, targeted delivery and therapeutic potency assessment. Advancements in exo-ncRNA methods and design will promote the development of therapeutics, revolutionizing the present landscape.

ANGPTL4 regulates the osteogenic differentiation of periodontal ligament stem cells

The molecular mechanism of mechanical force regulating the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) has not been clearly elucidated. In this study, two mRNA-seqs, GSE106887 and GSE109167, which contained several samples of PDLSCs under mechanical force, were downloaded from Gene Expression Omnibus. Differential expression analysis was firstly taken between GSE106887 and GSE109167, then the common 84 up-regulated genes and 26 down-regulated genes were selected. Function enrichment analysis was used to identify the key genes and pathways in PDLSCs subjected to the tension and compression force. PDLSCs were isolated from human periodontal ligament tissues. The effects of ANGPTL4 knockdown with shRNA on the osteogenic differentiation of PDLSCs were studied in vitro. Then, the orthodontic tooth movement (OTM) rat model was used to study the expression of HIF-1α and ANGPTL4 in alveolar bone remodeling in vivo. ANGPTL4 and the HIF-1 pathway were identified in PDLSCs subjected to the tension and compression force. alizarin red staining, alcian blue staining, and oil red O staining verified that PDLSCs had the ability of osteogenic, chondrogenic, and adipogenic differentiation, respectively. Verification experiment revealed that the expression of ANGPTL4 in PDLSCs significantly increased when cultured under osteogenic medium in vitro. While ANGPTL4 was knocked down by shRNA, the levels of ALPL, RUNX2, and OCN decreased significantly, as well as the protein levels of COL1A1, ALPL, RUNX2, and OCN. During the OTM, the expression of HIF-1α and ANGPTL4 in periodontal ligament cells increased on the tension and compression sides. We concluded the positive relationship between ANGPTL4 and osteogenic differentiation of PDLSCs.

[Activation of mir-30a-wnt/β-catenin signaling pathway upregulates cathepsin K expression to promote cementogenic differentiation of periodontal ligament stem cells]

OBJECTIVE

To explore the role of cathepsin K (CTSK) regulated by mir-30a-wnt/β-catenin signaling pathway in cementogenic differentiation of periodontal ligament stem cells (PDLSCs).

METHODS

Human PDLSCs isolated by limiting dilution culture were induced by enamel matrix protein derivative (EMD) for differentiation into cementoblast-like cells. MicroRNA chip technique was employed to screen the differentially expressed microRNAs in the cells during induced differentiation. The effect of inhibiting miR-30a on CTSK expression in the induced cells was examined using RT-PCR and Western blotting. Ceramic scaffolds coated with PDLSCs treated with EMD and transfected with the miR-30a inhibitor or a lentiviral vector for CTSK overexpression were prepared and implanted subcutaneously in nude mice, and 8 weeks later the cellular expressions of cementoblast markers CAP and CEMP-1 were detected with immunohistochemistry to verify whether CTSK participate in cementogenic differentiation of PDLSCs. The role of wnt signaling pathway in miR-30a-mediated regulation of CTSK expression was explored by examining CTSK protein expressions after blocking wnt signaling in PDLSCs.

RESULTS

In PDLSCs with EMD-induced differentiation into cementoblast-like cells, multiple microRNAs exhibited differential expressions; and among them, miR-30a was specifically and significantly up-regulated (P < 0.05). Up-regulation of miR-30a obviously increased the expression of CTSK (P < 0.05) and promoted PDLSCs to form cementum-like tissues with high expressions of CAP and CEMP-1. The regulatory effect of miR-30a on CTSK expression was obviously attenuated after inhibiting wnt/β-catenin signaling pathway.

CONCLUSION

EMD induces cementogenic differentiation of PDLSCs possibly by up-regulating the expression of miR-30a, which further activates the wnt/β-catenin signaling pathway to enhance the expression of CTSK.

Bioinformatics Analysis Identified miR-584-5p and Key miRNA-mRNA Networks Involved in the Osteogenic Differentiation of Human Periodontal Ligament Stem Cells

Human periodontal ligament cells (PDLCs) play an important role in periodontal tissue stabilization and function. In the process of osteogenic differentiation of PDLSCs, the regulation of molecular signal pathways are complicated. In this study, the sequencing results of three datasets on GEO were used to comprehensively analyze the miRNA-mRNA network during the osteogenic differentiation of PDLSCs. Using the GSE99958 and GSE159507, a total of 114 common differentially expressed genes (DEGs) were identified, including 62 up-regulated genes and 52 down-regulated genes. GO enrichment analysis was performed. The up-regulated 10 hub genes and down-regulated 10 hub genes were screened out by protein-protein interaction network (PPI) analysis and STRING in Cytoscape. Similarly, differentially expressed miRNAs (DEMs) were selected by limma package from GSE159508. Then, using the miRwalk website, we further selected 11 miRNAs from 16 DEMs that may have a negative regulatory relationship with hub genes. In vitro RT-PCR verification revealed that nine DEMs and 18 hub genes showed the same trend as the RNA-seq results during the osteogenic differentiation of PDLSCs. Finally, using miR-584-5p inhibitor and mimics, it was found that miR-584-5p negatively regulates the osteogenic differentiation of PDLSCs in vitro. In summary, the present results found several potential osteogenic-related genes and identified candidate miRNA-mRNA networks for the further study of osteogenic differentiation of PDLSCs.

Melatonin restores osteoporosis-impaired osteogenic potential of bone marrow mesenchymal stem cells and alleviates bone loss through the HGF/PTEN/Wnt/β-catenin axis

Background:

Previous studies reported that melatonin exerts its effect on mesenchymal stem cell (MSC) survival and differentiation into osteogenic and adipogenic lineage. In the current study we aimed to explore the effect of melatonin on osteoporosis and relevant mechanisms.

Methods:

Real-time qualitative polymerase chain reaction (RT-qPCR) and Western blot analysis were conducted to determine expression of HGF, PTEN, and osteoblast differentiation-related genes in ovariectomy (OVX)-induced osteoporosis mice and the isolated bone marrow MSCs (BMSCs). Pre-conditioning with melatonin (1 μmol/l, 10 μmol/l and 100 μmol/l) was carried out in OVX mice BMSCs. Bone microstructure was analyzed using micro-computed tomography and the contents of alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase 5b (TRAP5b) were detected by enzyme-linked immunosorbent assay in serum. BMSC proliferation was measured by cell-counting kit (CCK)-8 assay. Alizarin red S (ARS) staining and ALP activity assay were performed to assess BMSC mineralization and calcification. The activity of the Wnt/β-catenin pathway was evaluated by dual-luciferase reporter assay.

Results:

Melatonin prevented bone loss in OVX mice. Melatonin increased ALP expression and reduced TRAP5b expression. HGF and β-catenin were downregulated, while PTEN was upregulated in the femur of OVX mice. Melatonin elevated HGF expression and then stimulated BMSC proliferation and osteogenic differentiation. Additionally, HGF diminished the expression of PTEN, resulting in activated Wnt/β-catenin pathway both in vitro and in vivo. Furthermore, melatonin was shown to ameliorate osteoporosis in OVX mice via the HGF/PTEN/Wnt/β-catenin axis.

Conclusion:

Melatonin could potentially enhance osteogenic differentiation of BMSCs and retard bone loss through the HGF/PTEN/Wnt/β-catenin axis.

Carboxypeptidase E down-regulation regulates transcriptional and epigenetic profiles in pancreatic cancer cell line: A network analysis

BACKGROUND

Pancreatic cancer is a malignant tumor and its incidence has increased in recent years. Carboxypeptidase E (CPE) is a prohormone/proneuropeptide processing enzyme that has been shown to be associated with tumor growth and invasion in various cancers including pancreatic cancer.

OBJECTIVE

To understand the molecular mechanism underlying the proliferative effects of CPE in cancer cells.

METHODS

We down-regulated CPE gene expression in PANC-1 cell, a pancreatic cell line, and investigated mRNA, miRNA, circRNA and lncRNA expression profiling in PANC-1 cells from control group and CPE knock-down group by microarray analysis. We further validated the top 14 differentially expressed circRNAs by qRT-PCR.

RESULTS

Our results showed that CPE down-regulation caused decreased cell proliferation. The microarray data showed 107, 15, 299 and 360 differentially expressed mRNAs, miRNAs, circRNAs, and lncRNAs, respectively between control group and CPE knock-down group. Of Which, 41 mRNAs, 12 miRNAs, 133 circRNAs, and 262 lncRNAs were down-regulated; 66 mRNAs, 3 miRNAs, 166 circRNAs, and 98 lncRNAs were up-regulated. Bioinformatics analysis showed that the top significantly enriched pathways for the differentially expressed RNAs were related to cancer onset and/or progression, these included p53 signaling pathway, ECM-receptor interaction, focal adhesion and Wnt signaling pathway. We further performed network analysis to assess the mRNA, miRNA, circRNA and lncRNA correlations, and showed that HUWE1, hsa-miR-6780b-5p, has_circ_0058208 and lnc-G3BP1-3:8 were in the core position of the network.

CONCLUSIONS

Taken together, these results identified potential CPE regulated core genes and pathways for cell proliferation in pancreatic cancer cell, and therefore provide potential targets for the treatment of pancreatic cancer.

Lithium chloride promotes osteogenesis and suppresses apoptosis during orthodontic tooth movement in osteoporotic model via regulating autophagy

Osteoporosis is a widely distributed disease that may cause complications such as accelerated tooth movement, bone resorption, and tooth loss during orthodontic treatment. Promoting bone formation and reducing bone resorption are strategies for controlling these complications. For several decades, the autophagy inducer lithium chloride (LiCl) has been explored for bipolar . In this study, we investigated the autophagy-promoting effect of LiCl on bone remodeling under osteoporotic conditions during tooth movement. Ovariectomy was used to induce osteoporosis status in vivo. The results showed that LiCl rejuvenated autophagy, decreased apoptosis, and promoted bone formation, thus protecting tooth movement in osteoporotic mice. Furthermore, in vitro experiments showed that LiCl reversed the effects of ovariectomy on bone marrow-derived mesenchymal stem cells (BMSCs) extracted from ovariectomized mice, promoting osteogenesis and suppressing apoptosis by positively regulating autophagy. These findings suggest that LiCl can significantly decrease adverse effects of osteoporosis on bone remodeling, and that it has great potential significance in the field of bone formation during tooth movement in osteoporosis patients.

MiR-143-3p Inhibits Osteogenic Differentiation of Human Periodontal Ligament Cells by Targeting KLF5 and Inactivating the Wnt/β-Catenin Pathway

Human periodontal ligament cells (hPDLCs) play a vital role in cell regeneration and tissue repair with multi-directional differentiation potential. microRNAs (miRs) are implicated in the osteogenesis of hPDLCs. This study explored the mechanism of miR-143-3p in osteogenesis of hPDLCs. Osteogenic differentiation of isolated hPDLCs was induced. KLF5 expression during osteogenic differentiation of hPDLCs was detected and then silenced in hPDLCs. Binding relationship between KLF5 and miR-143-3p was predicted and verified. hPDLCs were treated with miR-143-3p mimic or overexpressing KLF5, and then osteogenic specific markers and mineralized nodules were measured. The key factors of the Wnt/β-catenin pathway during osteogenesis of hPDLCs were measured. KLF5 expression was upregulated during osteogenesis of hPDLCs. KLF5 silencing or miR-143-3p mimic reduced osteogenic specific markers and mineralized nodules. Overexpression of KLF5 could reverse the inhibitory effect of miR-143-3p on osteogenic differentiation. miR-143-3p mimic and KLF5 silencing inactivated the Wnt/β-catenin pathway. Activation of the Wnt/β-catenin pathway reversed the repression effect of miR-143-3p mimic on osteogenesis of hPDLCs. In conclusion, miR-143-3p inhibited osteogenic differentiation of hPDLCs by targeting KLF5 and inactivating the Wnt/β-catenin pathway.

Obesity regulates miR-467/HoxA10 axis on osteogenic differentiation and fracture healing by BMSC-derived exosome LncRNA H19

This study explored the therapeutic effect of bone marrow mesenchymal stem cell‐derived exosomes on the treatment of obesity‐induced fracture healing. Quantitative real‐time PCR was used to detect the expression of lncRNA H19, miR‐467 and Hoxa10 and combined with WB detection to detect osteogenic markers (RUNX2, OPN, OCN). Determine whether exosomes have entered BMSCs by immunofluorescence staining. Alkaline phosphatase (ALP) and alizarin red staining (ARS) staining were used to detect ALP activity and calcium deposition. We found that high‐fat treatment can inhibit the secretion of BMSCs‐derived exosomes and affect the expression of H19 carried by them. In vivo and in vitro experiments show that high‐fat or obesity factors can inhibit the expression of osteogenic markers and reduce the staining activity of ALP and ARS. The treatment of exosomes from normal sources can reverse the phenomenon of osteogenic differentiation and abnormal fracture healing. Further bioinformatics analysis found that miR‐467 as a regulatory molecule of lncRNA H19 and Hoxa10, and we verified the targeting relationship of the three through dual luciferase report experiments. Further, we found similar phenomena in ALP and ARS staining. Bone marrow mesenchymal stem cell‐derived exosomes improve fracture healing caused by obesity.

miR-296-5p Inhibits the Secretion of Pulmonary Surfactants in Pulmonary Epithelial Cells via the Downregulation of Wnt7b/β-Catenin Signaling

Neonatal respiratory distress syndrome (NRDS) is a common disease that occurs in premature infants. However, the mechanisms underlying the disease remain unclear. microRNAs (miRNAs) have been indicated to play a crucial role in the development of NRDS. In this study, we aimed to explore the regulatory mechanisms of miR-296-5p in NRDS. The expression levels of miR-296-5p in preterm infants with NRDS were determined using quantitative reverse-transcription polymerase chain reaction (RT-qPCR). A549 cells were transfected with lentiviral vectors encoding miR-296-5p, and the transfection efficiency was determined using RT-qPCR. Flow cytometry and CCK8 assay were performed to measure apoptosis and proliferation of A549 cells, respectively. The protein levels of pulmonary surfactant SP-A (SFTPA1), SP-B, Wnt7b, and β-catenin were measured using western blotting. We demonstrated an upregulation of miR-296-5p in NRDS. The miR-296-5p was successfully overexpressed in A549 cells via lentivirus transfection, and the upregulation of miR-296-5p inhibited cell proliferation and secretion of SP-A and SP-B and also induced downregulation of the Wnt7b/β-catenin in vitro. Therefore, miR-296-5p inhibits cell proliferation and secretion of pulmonary surfactants in A549 cells via downregulation of Wnt7b/β-catenin signaling.