Upregulation of circ_0076684 in osteosarcoma facilitates malignant processes by mediating miRNAs/CUX1.

Circular RNAs (circRNAs) are a newly appreciated type of endogenous noncoding RNAs that play vital roles in the development of various human cancers, including osteosarcoma (OS). In this study, we investigated three circRNAs (circ_0076684, circ_0003563, circ_0076691) from the RUNX Family Transcription Factor 2 (RUNX2) gene locus in OS. We found that the expression of circ_0076684, circ_0003563, circ_0076691, and RUNX2 mRNA is upregulated in OS, which is a consequence of CBX4-mediated transcriptional activation. Among these three RUNX2-circRNAs, only circ_0076684 is significantly associated with the clinical features and prognosis of OS patients. Functional experiments indicate that circ_0076684 promotes OS progression in vitro and in vivo. Circ_0076684 acts as a sponge for miR-370-3p, miR-140-3p, and miR-193a-5p, raising Cut Like Homeobox 1 (CUX1) expression by sponging these three miRNAs. Furthermore, we presented that circ_0076684 facilitates OS progression via CUX1. In conclusion, this study found that the expression of three circRNAs and RUNX2 mRNA from the RUNX2 gene locus is significantly upregulated in OS, as a result of CBX4-mediated transcriptional activation. Circ_0076684 raises CUX1 expression by sponging miR-370-3p, miR-140-3p, and miR-193a-5p, and facilitates OS progression via CUX1.

RUNX transcription factors are essential in maintaining epididymal epithelial differentiation.

Apart from the androgen receptor, transcription factors (TFs) that are required for the development and formation of the different segments of the epididymis have remained unknown. We identified TF families expressed in the developing epididymides, of which many showed segment specificity. From these TFs, down-regulation of runt related transcription factors (RUNXs) 1 and 2 expression coincides with epithelial regression in Dicer1 cKO mice. Concomitant deletion of both Runx1 and Runx2 in a mouse epididymal epithelial cell line affected cell morphology, adhesion and mobility in vitro. Furthermore, lack of functional RUNXs severely disturbed the formation of 3D epididymal organoid-like structures. Transcriptomic analysis of the epididymal cell organoid-like structures indicated that RUNX1 and RUNX2 are involved in the regulation of MAPK signaling, NOTCH pathway activity, and EMT-related gene expression. This suggests that RUNXs are master regulators of several essential signaling pathways, and necessary for the maintenance of proper differentiation of the epididymal epithelium.

[Chidamide Promotes Osteogenic Differentiation of Bone Marrow Mesenchymal Stromal Cells from Patients with Myelodysplastic Syndromes].

OBJECTIVE: To explore the effects and mechanisms of chidamide on the osteogenic differentiation of bone marrow mesenchymal stromal cells (MSC) from myelodysplastic syndromes (MDS). METHODS: MSC were isolated and cultured from bone marrow of MDS patients and healthy donors. CCK-8 assay was used to detect the effects of chidamide on the proliferation of MSC. The effects of chidamide on the activity of histone deacetylase (HDAC) in MSC was measured by a fluorescence assay kit and Western blot. Alkaline phosphatase (ALP) activity was detected on day 3 and calcium nodule formation was observed by Alizarin Red staining on day 21 after osteogenic differentiation. The expression of early and late osteogenic genes was detected on day 7 and day 21, respectively. RT-PCR and Western blot were used to detect the effects of chidamide on mRNA and protein expression of RUNX2 which is the key transcription factor during osteogenesis. RESULTS: As the concentration of chidamide increased, the proliferation of MSC was inhibited. However, at a low concentration (1 µmol/L), chidamide had no significant inhibitory effect on MSC proliferation but significantly inhibited HDAC activity. In MSC from both MDS patients and healthy donors, chidamide (1 µmol/L) significantly increased ALP activity, calcium nodule formation, thereby mRNA expression of osteogenic genes, and restored the reduced osteogenic differentiation ability of MDS-MSC compared to normal MSC. Mechanistic studies showed that the osteogenic-promoting effect of chidamide may be related to the upregulation of RUNX2 . CONCLUSION: Chidamide can inhibit HDAC activity in MSC, upregulate the expression of the osteogenic transcription factor RUNX2, and promote the osteogenic differentiation of MDS-MSC.

[A sericin hydrogel scaffold for sustained dexamethasone release modulates macrophage polarization to promote mandibular bone defect repair in rats].

OBJECTIVE: To evaluate the efficacy of a modified sericin hydrogel scaffold loaded with dexamethasone (SMH-CD/DEX) scaffold for promoting bone defect healing by stimulating anti-inflammatory macrophage polarization. METHODS: The light-curable SMH-CD/DEX scaffold was prepared using dexamethasone-loaded NH2-ß-cyclodextrin (NH2-ß-CD) and sericin hydrogel and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), biocompatibility assessment and drug release test. THP-1 macrophages incubated with the scaffold were examined for protein expressions of iNOS and Arg-1, mRNA expressions of IL-6, Il-10, Arg-1 and iNOS, and surface markers CD86 and CD206 using Western blotting, RT-qPCR, and flow cytometry. In a co-culture system of human periodontal ligament stem cells (HPDLSCs) and THP-1 macrophages, the osteogenic ability of the stem cells incubated with the scaffold was evaluated by detecting protein expressions of COL1A1 and Runx2 and expressions of ALP, Runx2, OCN and BMP2 mRNA, ALP staining, and alizarin red staining. In a rat model of mandibular bone defect, the osteogenic effect of the scaffold was assessed by observing bone regeneration using micro-CT and histopathological staining. RESULTS: In THP-1 macrophages, incubation with SMH-CD/DEX scaffold significantly enhanced protein expressions of Arg-1 and mRNA expressions of IL-10 and Arg-1 and lowered iNOS protein expression and IL-6 and iNOS mRNA expressions. In the co-culture system, SMH-CD/DEX effectively increased the protein expressions of COL1A1 and Runx2 and mRNA expressions of ALP and BMP2 in HPDLSCs and promoted their osteogenic differentiation. In the rat models, implantation of SMH-CD/DEX scaffold significantly promoted bone repair and bone regeneration in the bone defect. CONCLUSION: The SMH-CD/DEX scaffold capable of sustained dexamethasone release promotes osteogenic differentiation of stem cells and bone defect repair in rats by regulating M2 polarization.

Effects of sitagliptin activation of the stromal cell-derived factor-1/CXC chemokine receptor 4 signaling pathway on the proliferation, apoptosis, inflammation, and osteogenic differentiation of human periodontal ligament stem cells induced by lipopolysaccharide.

OBJECTIVES: This study aimed to investigate the effects of sitagliptin on the proliferation, apoptosis, inflammation, and osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) in lipopolysaccharide (LPS)-induced inflammatory microenvironment and its molecular mechanism. METHODS: hPDLSCs were cultured in vitro and treated with different concentrations of sitagliptin to detect cell viability and subsequently determine the experimental concentration of sitagliptin. An hPDLSCs inflammation model was established after 24 h of stimulation with 1 µg/mL LPS and divided into blank, control, low-concentration sitagliptin (0.5 µmol/L), medium-concentration sitagliptin (1 µmol/L), and high-concentration sitagliptin (2 µmol/L), high-concentrationsitagliptin+stromal cell derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4) pathway inhibitor (AMD3100) (2 µmol/L+10 µg/mL) groups. A cell-counting kit-8 was used to detect the proliferation activity of hPDLSCs after 24, 48, and 72 h culture. The apoptosis of hPDLSCs cultured for 72 h was detected by flow cytometry. After inducing osteogenic differentiation for 21 days, alizarin red staining was used to detect the osteogenic differentiation ability of hPDLSCs. The alkaline phosphatase (ALP) activity in hPDLSCs was determined using a kit. The levels of inflammatory factors [tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6] in the supernatant of hPDLSCs culture were detected by enzyme-linked immunosorbent assay. The mRNA expressions of osteogenic differentiation genes [Runt-associated transcription factor 2 (RUNX2), osteocalcin (OCN), osteopontin (OPN)], SDF-1 and CXCR4 in hPDLSCs were detected by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR). Western blot analysis was used to determine SDF-1 and CXCR4 protein expression in hPDLSCs. RESULTS: Compared with the blank group, the proliferative activity, number of mineralized nodules, staining intensity, ALP activity, and RUNX2, OCN, OPN mRNA, SDF-1, and CXCR4 mRNA and protein expression levels of hPDLSCs in the control group significantly decreased. The apoptosis rate and levels of TNF-α, IL-1ß, and IL-6 significantly increased (P<0.05). Compared with the control group, the proliferative activity, number of mineralized nodule, staining intensity, ALP activity, and RUNX2, OCN, OPN mRNA, SDF-1, and CXCR4 mRNA and protein expression levels of hPDLSCs in low-, medium-, and high-concentration sitagliptin groups increased. The apoptosis rate and levels of TNF-α, IL-1ß, and IL-6 decreased (P<0.05). AMD3100 partially reversed the effect of high-concentration sitagliptin on LPS-induced hPDLSCs (P<0.05). CONCLUSIONS: Sitagliptin may promote the proliferation and osteogenic differentiation of hPDLSCs in LPS-induced inflammatory microenvironment by activating the SDF-1/CXCR4 signaling pathway. Furthermore, it inhibited the apoptosis and inflammatory response of hPDLSCs.

Indoxyl Sulfate-Induced Valve Endothelial Cell Endothelial-to-Mesenchymal Transition and Calcification in an Integrin-Linked Kinase-Dependent Manner.

Calcific Aortic Valve Disease (CAVD) is a significant concern for cardiovascular health and is closely associated with chronic kidney disease (CKD). Aortic valve endothelial cells (VECs) play a significant role in the onset and progression of CAVD. Previous research has suggested that uremic toxins, particularly indoxyl sulfate (IS), induce vascular calcification and endothelial dysfunction, but the effect of IS on valve endothelial cells (VECs) and its contribution to CAVD is unclear. Our results show that IS reduced human VEC viability and increased pro-calcific markers RUNX2 and alkaline phosphatase (ALP) expression. Additionally, IS-exposed VECs cultured in pro-osteogenic media showed increased calcification. Mechanistically, IS induced endothelial-to-mesenchymal transition (EndMT), evidenced by the loss of endothelial markers and increased expression of mesenchymal markers. IS triggered VEC inflammation, as revealed by NF-kB activation, and decreased integrin-linked kinase (ILK) expression. ILK overexpression reversed the loss of endothelial phenotype and RUNX2, emphasizing its relevance in the pathogenesis of CAVD in CKD. Conversely, a lower dose of IS intensified some of the effects in EndMT caused by silencing ILK. These findings imply that IS affects valve endothelium directly, contributing to CAVD by inducing EndMT and calcification, with ILK acting as a crucial modulator.

Activation of CaMKII/HDAC4 by SDF1 contributes to pulmonary arterial hypertension via stabilization Runx2.

Stromal derived factor 1 (SDF1) has been shown to be involved in the pathogenesis of pulmonary artery hypertension (PAH). However, the detailed molecular mechanisms remain unclear. To address this, we utilized primary cultured rat pulmonary artery smooth muscle cells (PASMCs) and monocrotaline (MCT)-induced PAH rat models to investigate the mechanisms of SDF1 driving PASMCs proliferation and pulmonary arterial remodeling. SDF1 increased runt-related transcription factor 2 (Runx2) acetylation by Calmodulin (CaM)-dependent protein kinase II (CaMKII)-dependent HDAC4 cytoplasmic translocation, elevation of Runx2 acetylation conferred its resistance to proteasome-mediated degradation. The accumulation of Runx2 further upregulated osteopontin (OPN) expression, finally leading to PASMCs proliferation. Blocking SDF1, suppression of CaMKII, inhibition the nuclear export of HDAC4 or silencing Runx2 attenuated pulmonary arterial remodeling and prevented PAH development in MCT-induced PAH rat models. Our study provides novel sights for SDF1 induction of PASMCs proliferation and suggests that targeting SDF1/CaMKII/HDAC4/Runx2 axis has potential value in the management of PAH.

Effect of simultaneous and sequential use of TGF-ß1 and TGF-ß3 with FGF-2 on teno/ligamentogenic differentiation of periodontal ligament stem cells.

OBJECTIVE: The periodontal ligament is a crucial part of the periodontium, and its regeneration is challenging. This study compares the effect of simultaneous and sequential use of FGF-2 and TGF-ß1 with FGF-2 and TGF-ß3 on the periodontal ligament stem cells (PDLSCs) teno/ligamentogenic differentiation. DESIGN: This study comprises ten different groups. A control group with only PDLSCs; FGF-2 group containing PDLSCs with a medium culture supplemented with FGF-2 (50 ng/mL). In other experimental groups, different concentrations (5 ng/mL or 10 ng/mL) of TGF-ß1&-ß3 simultaneously or sequentially were combined with FGF-2 on the cultured PDLSCs. TGF-ß was added to the medium after day 3 in the sequential groups. Methyl Thiazolyl Tetrazolium (MTT) assay on days 3, 5, and 7 and Quantitative Real-time Polymerase Chain Reaction (RT-qPCR) analysis after day 7 were conducted to investigate PLAP1, SCX, and COL3A1, RUNX2 genes. All experiments were conducted in a triplicate. The One-way and Two-way ANOVA with Tukey post hoc were utilized to analyze the results of the MTT and RT-qPCR tests, respectively. A p-value less than 0.05 is considered significant. RESULTS: The proliferation of cells on days 3, 5, and 7 was not significantly different among different experimental groups (P > 0.05). A higher expression of the PLAP1, SCX, and COL3A1 have been seen in groups with sequential use of growth factors; among these groups, the group using 5 ng/mL of TGF-ß3 led other groups with the most amount of significant upregulation in PLAP1(17.69 ± 1.11 fold; P < 0.0001), SCX (5.71 ± 0.38 fold; P < 0.0001), and COL1A3 (6.35 ± 0.39 fold; P < 0.0001) expression, compared to the control group. The expression of the RUNX2 decreased in all groups compared to the control group; this reduction was more in groups with sequential use of growth factors. CONCLUSION: The sequential use of growth factors can be more effective than simultaneous use in teno/ligamentogenic differentiation of PDLSCs. Moreover, treatment with 5 ng/mL TGF-ß3 after FGF-2 was more effective than TGF-ß1.

The bone-protective benefits of kaempferol combined with metformin by regulation of osteogenesis-angiogenesis coupling in OVX rats.

This study was to investigate the potential mechanisms of treatment with metformin (Met) combined with kaempferol (Kae) against postmenopausal osteoporosis. Experiments were conducted in both ovariectomy (OVX)-induced osteoporosis rats and in vitro using RAW264.7 cells, MC3T3-E1 cells, and HUVECs. Results demonstrated the therapeutic effect of Met combined with Kae on osteoporosis. In vivo, Kae alone and in combination with Met treatments enhanced tibial trabecular microstructure, bone mineral density (BMD), and mechanical properties in OVX rats without causing hepatotoxicity and nephrotoxicity. It also reduced bone resorption markers (CTX-1 and TRAP) and increased the bone formation marker (PINP) level in the serum of OVX rats. The expression of bone resorption marker TRAP was reduced, while bone formation markers Runx2 and ALP were enhanced in the bone tissue of OVX rats. Furthermore, Met combined with Kae also promoted the expression of angiogenesis-related markers CD31 and VEGF in OVX rats. In vitro, MC3T3-E1s cells treated with Met combined with Kae showed higher expression of ALP, Runx2, and VEGF. Interestingly, the treatment did not directly promote HUVECs migration and angiogenesis, but enhanced osteoblast-mediated angiogenesis by upregulating VEGF levels. Additionally, Met combined with Kae treatment promoted VEGF secretion in MC3T3-E1, and activated the Notch intracelluar pathway by upregulating HES1 and HEY1 in HUVECs. Meantime, their stimulation on CD31 expression were inhibited by DAPT, a Notch signaling inhibitor. Overall, this study demonstrates the positive effects of Met combined with Kae on osteoporotic rats by promoting osteogenesis-angiogenesis coupling, suggesting their potential application in postmenopausal osteoporosis.

Preliminary investigation into the impact of BPA on osteoblast activity and bone development: In vitro and in vivo models.

Bisphenol A (BPA), an ingredient in consumer products, has been suggested that it can interfere with bone development and maintenance, whereas the molecule mechanism remains unclear. The objective of this study is to investigate the effect of BPA on early bone differentiation and metabolism, and its potential molecule mechanism by employing hFOB1.19 cell as an in vitro model, as well as larval zebrafish as an in vivo model. The in vitro experiments indicated that BPA decreased cell viability, inhibited osteogenic activity (such as ALP, RUNX2), increased ROS production, upregulated transcriptional or protein levels of apoptosis-related molecules (such as Caspase 3, Caspase 9), while suppressed transcriptional or protein levels of pyroptosis-specific markers (TNF-α, TNF-ß, IL-1ß, ASC, Caspase 1, and GSDMD). Moreover, the evidences from in vivo model demonstrated that exposure to BPA distinctly disrupted pharyngeal cartilage, craniofacial bone development, and retarded bone mineralization. The transcriptional level of bone development-related genes (bmp2, dlx2a, runx2, and sp7), apoptosis-related genes (bcl2), and pyroptosis-related genes (cas1, nlrp3) were significantly altered after treating with BPA in zebrafish larvae. In summary, our study, combining in vitro and in vivo models, confirmed that BPA has detrimental effects on osteoblast activity and bone development. These effects may be due to the promotion of apoptosis, the initiation of oxidative stress, and the inhibition of pyroptosis.

mir-150-5p inhibits the osteogenic differentiation of bone marrow-derived mesenchymal stem cells by targeting irisin to regulate the p38/MAPK signaling pathway.

PURPOSE: To study the effect of miR-150-5p on the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs), and further explore the relationship between its regulatory mechanism and irisin. METHODS: We isolated mouse BMSCs, and induced osteogenic differentiation by osteogenic induction medium. Using qPCR to detect the expression of osteogenic differentiation-related genes, western blot to detect the expression of osteogenic differentiation-related proteins, and luciferase reporter system to verify that FNDC5 is the target of miR-150-5p. Irisin intraperitoneal injection to treat osteoporosis in mice constructed by subcutaneous injection of dexamethasone. RESULTS: Up-regulation of miR-150-5p inhibited the proliferation of BMSCs, and decreased the content of osteocalcin, ALP activity, calcium deposition, the expression of osteogenic differentiation genes (Runx2, OSX, OCN, OPN, ALP and BMP2) and protein (BMP2, OCN, and Runx2). And down-regulation of miR-150-5p plays the opposite role of up-regulation of miR-150-5p on osteogenic differentiation of BMSCs. Results of luciferase reporter gene assay showed that FNDC5 gene was the target gene of miR-150-5p, and miR-150-5p inhibited the expression of FNDC5 in mouse BMSCs. The expression of osteogenic differentiation genes and protein, the content of osteocalcin, ALP activity and calcium deposition in BMSCs co-overexpressed by miR-150-5p and FNDC5 was significantly higher than that of miR-150-5p overexpressed alone. In addition, the overexpression of FNDC5 reversed the blocked of p38/MAPK pathway by the overexpression of miR-150-5p in BMSCs. Irisin, a protein encoded by FNDC5 gene, improved symptoms in osteoporosis mice through intraperitoneal injection, while the inhibitor of p38/MAPK pathway weakened this function of irisin. CONCLUSION: miR-150-5p inhibits the osteogenic differentiation of BMSCs by targeting irisin to regulate the/p38/MAPK signaling pathway, and miR-150-5p/irisin/p38 pathway is a potential target for treating osteoporosis.

Mechanism of KDM5A-mediated H3K4me3 modification in the osteogenic differentiation of mesenchymal stem cells in steroid-induced osteonecrosis of the femoral head.

OBJECTIVES: Steroid-induced osteonecrosis of the femoral head (SONFH) is characterized by impaired osteogenesis in bone marrow mesenchymal stem cells (BMSCs). This study investigates the role of lysine-specific demethylase 5A (KDM5A) in SONFH to identify potential therapeutic targets. METHODS: Human BMSCs were isolated and characterized for cell surface markers and differentiation capacity. A SONFH cell model was established using dexamethasone treatment. BMSCs were transfected with KDM5A overexpression vectors or si-KDM5A, and the expression of KDM5A, miR-107, runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), and osteopontin (OPN) was assessed. Alizarin red staining was used to observe mineralization nodules, while alkaline phosphatase activity and cell viability were measured. The enrichment of KDM5A and histone 3 lysine 4 trimethylation (H3K4me3) on the promoters of RUNX2, OCN, and OPN was analyzed. The binding between miR-107 and KDM5A 3'UTR was validated, and the combined effect of miR-107 overexpression and KDM5A overexpression on BMSC osteogenic differentiation was evaluated. RESULTS: KDM5A was upregulated in BMSCs from SONFH. Inhibition of KDM5A promoted osteogenic differentiation of BMSCs, associated with increased RUNX2, OCN, and OPN promoters. KDM5A bound to the promoters of RUNX2, OCN, and OPN, leading to reduced H3K4me3 levels and downregulation of their expression. Overexpression of miR-107 inhibited KDM5A and enhanced BMSC osteogenic differentiation. CONCLUSION: KDM5A negatively regulates BMSC osteogenic differentiation by modulating H3K4me3 levels on the promoters of key osteogenic genes. miR-107 overexpression counteracts the inhibitory effect of KDM5A on osteogenic differentiation. These findings highlight the potential of targeting the KDM5A/miR-107 axis for SONFH therapy.

Osteoblastic differentiation and changes in the redox state in pulp stem cells by laser treatment.

The aim of this study was to determine the effect of low-level laser therapy (LLLT) on cell proliferation, mitochondrial membrane potential changes (∆Ψm), reactive oxygen species (ROS), and osteoblast differentiation of human dental pulp stem cells (hDPSCs). These cells were irradiated with 660- and 940-nm lasers for 5 s, 50 s, and 180 s. Cell proliferation was assessed using the resazurin assay, cell differentiation by RUNX2 and BMP2 expression, and the presence of calcification nodules using alizarin-red S staining. ROS was determined by the dichlorofluorescein-diacetate technique and changes in ∆Ψm by the tetramethylrhodamine-ester assay. Data were analyzed by a Student's t-test and Mann-Whitney U test. The 940-nm wavelength for 5 and 50 s increased proliferation at 4 days postirradiation. After 8 days, a significant decrease in proliferation was observed in all groups. Calcification nodules were evident in all groups, with a greater staining intensity in cells treated with a 940-nm laser for 50 s, an effect that correlated with increased RUNX2 and BMP2 expression. ROS production and Δψm increased independently of irradiation time. In conclusion, photobiomodulation (PBM) with LLLT induced morphological changes and reduced cell proliferation rate, which was associated with osteoblastic differentiation and increased ROS and Δψm, independent of wavelength and time.

METTL3 Promotes Osteogenic Differentiation of Human Periodontal Ligament Stem Cells through IGF2BP1-Mediated Regulation of Runx2 Stability.

N6-Methyladenosine (m6A) has been reported to play a dynamic role in osteoporosis and bone metabolism. However, whether m6A is involved in the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) remains unclear. Here, we found that methyltransferase-like 3 (METTL3) was up-regulated synchronously with m6A during the osteogenic differentiation of hPDLSCs. Functionally, lentivirus-mediated knockdown of METTL3 in hPDLSCs impaired osteogenic potential. Mechanistic analysis further showed that METTL3 knockdown decreased m6A methylation and reduced IGF2BP1-mediated stability of runt-related transcription factor 2 (Runx2) mRNA, which in turn inhibited osteogenic differentiation. Therefore, METTL3-based m6A modification favored osteogenic differentiation of hPDLSCs through IGF2BP1-mediated Runx2 mRNA stability. Our study shed light on the critical roles of m6A on regulation of osteogenic differentiation in hPDLSCs and served novel therapeutic approaches in vital periodontitis therapy.

Exploring the Interplay of RUNX2 and CXCR4 in Melanoma Progression.

Overexpression of the Runt-related transcription factor 2 (RUNX2) has been reported in several cancer types, and the C-X-C motif chemokine receptor 4 (CXCR4) has an important role in tumour progression. However, the interplay between CXCR4 and RUNX2 in melanoma cells remains poorly understood. In the present study, we used melanoma cells and a RUNX2 knockout (RUNX2-KO) in vitro model to assess the influence of RUNX2 on CXCR4 protein levels along with its effects on markers associated with cell invasion and autophagy. Osteotropism was assessed using a 3D microfluidic model. Moreover, we assessed the impact of CXCR4 on the cellular levels of key cellular signalling proteins involved in autophagy. We observed that melanoma cells express both RUNX2 and CXCR4. Restored RUNX2 expression in RUNX2 KO cells increased the expression levels of CXCR4 and proteins associated with the metastatic process. The protein markers of autophagy LC3 and beclin were upregulated in response to increased CXCR4 levels. The CXCR4 inhibitor WZ811 reduced osteotropism and activated the mTOR and p70-S6 cell signalling proteins. Our data indicate that the RUNX2 transcription factor promotes the expression of the CXCR4 chemokine receptor on melanoma cells, which in turn promotes autophagy, cell invasiveness, and osteotropism, through the inhibition of the mTOR signalling pathway. Our data suggest that RUNX2 promotes melanoma progression by upregulating CXCR4, and we identify the latter as a key player in melanoma-related osteotropism.

A synthetic, closed-looped gene circuit for the autonomous regulation of RUNX2 activity during chondrogenesis.

The transcription factor RUNX2 is a key regulator of chondrocyte phenotype during development, making it an ideal target for prevention of undesirable chondrocyte maturation in cartilage tissue-engineering strategies. Here, we engineered an autoregulatory gene circuit (cisCXp-shRunx2) that negatively controls RUNX2 activity in chondrogenic cells via RNA interference initiated by a tunable synthetic Col10a1-like promoter (cisCXp). The cisCXp-shRunx2 gene circuit is designed based on the observation that induced RUNX2 silencing after early chondrogenesis enhances the accumulation of cartilaginous matrix in ATDC5 cells. We show that the cisCXp-shRunx2 initiates RNAi of RUNX2 in maturing chondrocytes in response to the increasing intracellular RUNX2 activity without interfering with early chondrogenesis. The induced loss of RUNX2 activity in turn negatively regulates the gene circuit itself. Moreover, the efficacy of RUNX2 suppression from cisCXp-shRunx2 can be controlled by modifying the sensitivity of cisCXp promoter. Finally, we show the efficacy of inhibiting RUNX2 in preventing matrix loss in human mesenchymal stem cell-derived (hMSC-derived) cartilage under conditions that induce chondrocyte hypertrophic differentiation, including inflammation. Overall, our results demonstrated that the negative modulation of RUNX2 activity with our autoregulatory gene circuit enhanced matrix synthesis and resisted ECM degradation by reprogrammed MSC-derived chondrocytes in response to the microenvironment of the degenerative joint.

Calcium absorption by Alaska pollock surimi protein hydrolysate promotes osteoblast differentiation.

The calcium-binding capacity and osteoblast proliferation and differentiation were studied in Alaska pollock surimi hydrolysate (APSH) using a system that mimics the gastrointestinal digestive system. Evaluation of the calcium absorption-promoting ability of APSH revealed that the best calcium-binding ability was achieved after hydrolysis with a combination of pepsin, α-chymotrypsin, and trypsin, and separation into <3 kDa (APSH-I), 3-5 kDa (APSH-II), 5-10 kDa (APSH-III), and <10 kDa (APSH-IV) fractions. Scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis confirmed that the hydrolysate and calcium ions formed a complex. Comparison of the calcium absorption capacity using Caco-2 cells showed that calcium absorption was promoted by these hydrolysates. Measurement of the osteoblast activation revealed higher alkaline phosphatase activity, collagen synthesis, and mineralization effect for the low-molecular-weight hydrolysate (LMH) than for the other hydrolysates. In addition, LMH promoted the expression of osteocalcin, osteopontin, and bone morphogenetic protein-2 and -4, which are hormones related to bone formation. Expression of the Runx2 transcription factor, which regulates the expression of these hormones, also increased. These results suggest that Alaska pollock surimi protein hydrolysates prepared using a system that mimics gastrointestinal hydrolysis may result in better osteoblast proliferation and bone health than those prepared using other proteases.

Runx2 Regulates Galnt3 and Fgf23 Expressions and Galnt3 Decelerates Osteoid Mineralization by Stabilizing Fgf23.

Runx2 (runt related transcription factor 2) is an essential transcription factor for osteoblast proliferation and differentiation. Uridine diphosphate (UDP)-N-acetylgalactosamine (GalNAc): polypeptide GalNAc-transferase 3 (Galnt3) prevents proteolytic processing of fibroblast growth factor 23 (Fgf23), which is a hormone that regulates the serum level of phosphorus. Runx2 and Galnt3 were expressed in osteoblasts and osteocytes, and Fgf23 expression was restricted to osteocytes in bone. Overexpression and knock-down of Runx2 upregulated and downregulated, respectively, the expressions of Galnt3 and Fgf23, and Runx2 directly regulated the transcriptional activity of Galnt3 in reporter assays. The expressions of Galnt3 and Fgf23 in osteoblast-specific Runx2 knockout (Runx2fl/flCre) mice were about half those in Runx2fl/fl mice. However, the serum levels of phosphorus and intact Fgf23 in Runx2fl/flCre mice were similar to those in Runx2fl/fl mice. The trabecular bone volume was increased during aging in both male and female Galnt3-/- mice, but the osteoid was reduced. The markers for bone formation and resorption in Galnt3-/- mice were similar to the control in both sexes. Galnt3-/- mice exhibited hyperphosphatemia and hypercalcemia, and the intact Fgf23 was about 40% that of wild-type mice. These findings indicated that Runx2 regulates the expressions of Galnt3 and Fgf23 and that Galnt3 decelerates the mineralization of osteoid by stabilizing Fgf23.

Analysis of the cytotoxicity and bioactivity of CeraSeal, BioRoot™ and AH Plus® sealers in pre-osteoblast lineage cells.

BACKGROUND: The objective of the present study was to evaluate in vitro the cytotoxicity and bioactivity of various endodontic sealers (CeraSeal, BioRoot™ and AH Plus®) in pre-osteoblast mouse cells (MC3T3 cells). METHODS: MC3T3 cells (ATCC CRL-2594) were plated in 1 × 104 cells/well in 96-well plates in contact with endodontic sealers at concentrations of 1:10 and 1:100. Cell viability was evaluated by MTT assay after 24 and 48 h. In addition, sealer bioactivity was measured by RT-PCR for mediator of inflammation (Tnf, Ptgs2) and mineralization (Runx2, Msx1, Ssp1 and Dmp1) after 24 h and by Alizarin Red S Assay of mineralization after 28 days. Data were analyzed using one-way ANOVA followed by the Tukey's post-test at a significance level of 5%. RESULTS: BioRoot™ presented 24-hour cytotoxicity (p < 0.05) at 1:10 concentration. In the period of 48 h, no endodontic cement was cytotoxic to the cells compared to the control (p > 0.05). TNF-α gene expression was induced by AH Plus® (p < 0.05), while Ptgs2 was induced by the CeraSeal and BioRoot™ (p < 0.05). The expression of Runx2 was stimulated by BioRoot™ and AH Plus® (p < 0.05). In contrast, the expression of Dmp-1 Dmp1 was higher for the CeraSeal and BioRoot™ (p < 0.05). Nonetheless, the sealers did not impact the formation of mineralization nodules (p > 0.05). CONCLUSION: CeraSeal, BioRoot™ and AH Plus® sealers were not cytotoxic to MC3T3 cells within 48 h, but differentially induced the expression of genes related to inflammation and mineralization without impacting biomineralization by the cells.

[Ubiquitin-specific protease 42 regulates osteogenic differentiation of human adipose-derived stem cells].

OBJECTIVE: To explore the effect of ubiquitin-specific protease 42 (USP42) on osteogenic differentiation of human adipose-derived stem cells (hASCs) in vivo and in vitro. METHODS: A combination of experiments was carried out with genetic depletion of USP42 using a lentiviral strategy. Alkaline phosphatase (ALP) staining and quantification, alizarin red S (ARS) staining and quantification were used to determine the osteogenic differentiation ability of hASCs under osteogenic induction between the experimental group (knockdown group and overexpression group) and the control group. Quantitative reverse transcription PCR (qRT-PCR) was used to detect the expression levels of osteogenesis related genes in the experimental group and control group, and Western blotting was used to detect the expression levels of osteogenesis related proteins in the experimental group and control group. Nude mice ectopic implantation experiment was used to evaluate the effect of USP42 on the osteogenic differentiation of hASCs in vivo. RESULTS: The mRNA and protein expressions of USP42 in knockdown group were significantly lower than those in control group, and those in overexpression group were significantly higher than those in control group. After 7 days of osteogenic induction, the ALP activity in the knockdown group was significantly higher than that in the control group, and ALP activity in overexpression group was significantly lower than that in control group. After 14 days of osteogenic induction, ARS staining was significantly deeper in the knockdown group than in the control group, and significantly lighter in overexpression group than in the control group. The results of qRT-PCR showed that the mRNA expression levels of ALP, osterix (OSX) and collagen type Ⅰ (COLⅠ) in the knockdown group were significantly higher than those in the control group after 14 days of osteogenic induction, and those in overexpression group were significantly lower than those in control group. The results of Western blotting showed that the expression levels of runt-related transcription factor 2 (RUNX2), OSX and COLⅠ in the knockout group were significantly higher than those in the control group at 14 days after osteogenic induction, while the expression levels of RUNX2, OSX and COLⅠ in the overexpression group were significantly lower than those in the control group. Hematoxylin-eosin staining of subcutaneous grafts in nude mice showed that the percentage of osteoid area in the knockdown group was significantly higher than that in the control group. CONCLUSION: Knockdown of USP42 can significantly promote the osteogenic differentiation of hASCs in vitro and in vivo, and overexpression of USP42 significantly inhibits in vivo osteogenic differentiation of hASCs, and USP42 can provide a potential therapeutic target for bone tissue engineering.