Runx2 mRNA Research Articles

Delivery of m7G methylated Runx2 mRNA by bone-targeted lipid nanoparticle promotes osteoblastic bone formation in senile osteoporosis

The loss of bone and destruction of bone microstructure due to aging in senile osteoporosis (SOP) significantly impair the health and quality of life of the elderly. The pathogenesis of SOP is primarily related to osteogenic deficiency, attenuation of osteoblast function, insufficient bone formation, and eventual bone loss. While METTL1 is the major reported methyltransferase to catalyze RNA 7-methylguanosine (m7G) methylation, regulating mRNA transcription, miRNA biosynthesis, biological function, tRNA stability, RNA intracellular processing, and maturation, its role in the pathogenesis of SOP and osteogenic differentiation of BMSCs has not been studied. In this research, we found a significant decrease in METTL1 in BMSCs from SOP patients. Deletion of METTL1 significantly inhibited m7G modification of Runx2, impeding osteogenic differentiation of BMSCs in vitro and inducing SOP in vivo. We further developed bone-targeted lipid nanoparticles containing the m7G methylated Runx2 mRNA (ZA-m7G Runx2 mRNA-LNPs), which significantly promoted bone repair and formation in the bone defect mouse model as well as the SOP mouse. This study provides new basic theoretical theory and treatment strategies for the prevention and treatment of SOP by revealing a critical m7G RNA modification mechanism of osteogenic differentiation disorders of BMSCs in the pathogenesis of SOP.

Abstract A145: CBFβ supports global protein translation in osteosarcoma and may provide a new therapeutic target

Abstract Background: Core binding factor beta (CBFβ) is a binding partner to the RUNX family of DNA binding transcription factors (RUNX1-3) and acts as a transcriptional co-activator by allosterically increasing their affinity for DNA. RUNX2 is the master regulator of bone growth and differentiation, and its binding to CBFβ is of particular interest to osteosarcoma (OS) research. Notably, increased expression of each is correlated with poor disease-free and overall survival in numerous sarcomas. CBFβ’s transcriptional role is well-understood but recent research in breast cancer cells proposes a non-canonical role in the regulation of protein translation, influencing translation of hundreds of mRNA transcripts via binding with heterogenous nuclear ribonucleoprotein K (hnRNPK). The binding of CBFβ to hnRNPK or RUNX1 is reportedly mutually exclusive, suggesting possible interplay between the two roles. We hypothesize that CBFβ regulates protein translation in OS, participating in the translation of RUNX2 and other oncoproteins, promoting a malignant phenotype. Furthermore, we propose that disrupting its translational role may result in an antitumor effect. While CBFβ’s transcriptional activities are well-characterized, we endeavored to isolate its translational role and investigate its contribution to OS. Methods: CRISPR/Cas9 was used to generate a CBFβ knockout (KO) U2OS cell line, while site-directed mutagenesis of CBFβ and lentiviral transduction of U2OS CBFβ KO cells was used to generate cell lines expressing FLAG-tagged wild type (WT) mutant CBFβ. Western Blotting (WB) was used to assess changes in protein expression and subcellular localization while RUNX2 mRNA expression was measured via qPCR and RNAseq. CBFβ’s interacting partners were identified by Immunoprecipitation Mass Spectrometry (IP-MS). Cellular electro-thermal shift assay was used to evaluate influences of CBFβ mutations on RUNX2 and hnRNPK binding. The Click-IT system followed by WB and IP-MS were used to assess global protein translation and synthesis rates of specific proteins, respectively. Results: CBFβ and hnRNPK interact in U2OS cells and loss of CBFβ leads to a decrease in global protein translation. This results in decreased RUNX2 protein, but not mRNA, expression. Re-introduction of WT CBFβ caused RUNX2 protein levels to recover while expression of CBFβ with key mutations in the binding interface abrogated this effect. Importantly, we observed this was not due to direct protection of RUNX2 from proteasomal degradation by WT CBFβ. We identified a cohort of proteins that appear to be translationally regulated by CBFβ and investigated the impact of CBFβ mutations on its translational activities and RUNX2 binding. We also identified a list of putative CBFβ protein-protein interactions in human OS cells that are altered by these mutations. Conclusions: CBFβ appears to participate in protein translation in OS, regulating the expression of numerous oncoproteins including RUNX2. Key mutations in CBFβ designed to interrupt RUNX2 binding also affect this non-canonical activity of CBFβ. Citation Format: Nicholas A Oldberg, Dayn R Godinez, Luke A Wittenburg. CBFβ supports global protein translation in osteosarcoma and may provide a new therapeutic target [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A145.

3D-printed TCP-HA scaffolds delivering MicroRNA-302a-3p improve bone regeneration in a mouse calvarial model

ObjectiveTo demonstrate hydroxyapatite nanoparticles modified with cationic functional molecules. 3-aminopropyltriethoxysilane (HA-NPs-APTES) carrying microRNA-302a-3p (miR) in the 3D-printed tricalcium phosphate/Hydroxyapatite (TCP/HA) scaffold can increase healing of the critical-sized bone defect.Materials and methods3D-printed TCP/HA were modified with HA-NPs-APTES by two methods (M1, M2). The dispersion of particles was visualized by fluorescent microscopy. Biocompatibility of the scaffolds was tested by alizarin assay. Delivery of miR to the cells and osteogenic gene expression were evaluated by qPCR. After selecting best method (M2), scaffolds, scaffolds+HA-NPs-APTES with or without miR were implanted in 4 mm mouse calvarium defect (n = 4 per group). After 2,4 and 6 weeks, bone regeneration were evaluated by microCT and histology sections.ResultsBoth M1 and M2 scaffolds were biocompatible with cell adhesion on its surface. M2 scaffold showed significant increase of miR, suggesting successful delivery, resulted in downregulation of its target mRNA COUP-TFII, and upregulation of RUNX2 mRNA. Calvarium defect with M2 scaffold also showed significantly higher BV/TV and higher number of filled spaces at all time points. Histomorphometry demonstrated new bone formed at the center of the HA-NPs-APTES-miR scaffold earlier than controls.ConclusionTCP/HA scaffold modified with HA-NPs-APTES facilitated delivery of miR and enhanced bone regeneration.

Structural identification of an polysaccharide isolated from Epimedium brevicornum and its beneficial effect on promoting osteogenesis in osteoblasts induced by high glucose

AimDiabetes osteoporosis (DOP) is a chronic bone metabolic disease induced by diabetes, whose morbidity continues to increase. Epimedium brevicornum Maxim (EB), a popular Chinese traditional medicine, has been used to treat bone diseases in China for thousands of years. But its material basis and specific mechanism of action are not clear. MethodsEpimedium brevicornum crude polysaccharide (EPE) is the main component, in this research the characterized the structure of EBPC1 purified from EPE was detected and its effects on cell proliferation, differentiation, and cytoskeletal in osteoblasts induced by high glucose. ResultsThe molecular weight of EBPC1 was 10.5 kDa. It was mainly comprised of glucose and galactose, and the backbone of EBPC1 was→4)-α-D-Galp-(1→4)-α-D-Galp-(1→6)-β-D-Galp-(1→6)-β-D-Galp-(1→4)-α-D-Glcp-(1→4)-α-D-Glcp-(1→. The results from in vitro experiments revealed that EBPC1 significantly increased alkaline phosphatase (ALP) activity and mineralized nodule formation in primary osteoblasts, also significantly up-regulated expression of Alp mRNA and Runx2 mRNA in the presence of EBPC1 pretreatment. Moreover, EBPC1 modulated apoptosis via the regulation of Bax/Bcl2. ConclusionThese results indicate that EBPC1 treatment can promote osteogenesis during DOP, which can ameliorate apoptosis by regulating Bax/Bcl2 and accelerating osteogenesis in osteoblasts.

Chitin scaffolds derived from the marine demosponge Aplysina fistularis stimulate the differentiation of dental pulp stem cells.

The use of stem cells for tissue regeneration is a prominent trend in regenerative medicine and tissue engineering. In particular, dental pulp stem cells (DPSCs) have garnered considerable attention. When exposed to specific conditions, DPSCs have the ability to differentiate into osteoblasts and odontoblasts. Scaffolds are critical for cell differentiation because they replicate the 3D microenvironment of the niche and enhance cell adhesion, migration, and differentiation. The purpose of this study is to present the biological responses of human DPSCs to a purified 3D chitin scaffold derived from the marine demosponge Aplysina fistularis and modified with hydroxyapatite (HAp). Responses examined included proliferation, adhesion, and differentiation. The control culture consisted of the human osteoblast cell line, hFOB 1.19. Electron microscopy was used to examine the ultrastructure of the cells (transmission electron microscopy) and the surface of the scaffold (scanning electron microscopy). Cell adhesion to the scaffolds was determined by neutral red and crystal violet staining methods. An alkaline phosphatase (ALP) assay was used for assessing osteoblast/odontoblast differentiation. We evaluated the expression of osteogenic marker genes by performing ddPCR for ALP, RUNX2, and SPP1 mRNA expression levels. The results show that the chitin biomaterial provides a favorable environment for DPSC and hFOB 1.19 cell adhesion and supports both cell proliferation and differentiation. The chitin scaffold, especially with HAp modification, isolated from A. fistularis can make a significant contribution to tissue engineering and regenerative medicine.

Analysis of Zinc and Stromal Immunity in Disuse Osteoporosis: Mendelian Randomization and Transcriptomic Analysis.

Disuse osteoporosis is known to be primarily caused by a lack of exercise. However, the causal relationships between zinc and immunity and disuse osteoporosis remain unknown. This study investigated these relationships and their potential mechanisms. This study was an integrative study combining genome-wide association studies and transcriptomics. Two-sample Mendelian randomization analysis (MR) was used to analyze the causal relationships between exposures (zinc, immunity, physical activity) and the outcome (osteoporosis) with the aid of single-nucleotide polymorphisms (SNPs) as instrumental variables (IVs). Four models, MR-Egger, inverse variance weighted, weighted median and MR-Pleiotrophy RESidual Sum and Outlier (MRPRESSO), were used to calculate odds ratio values. Sensitivity and heterogeneity analyses were also performed using MRPRESSO and MR-Egger methods. The mRNA transcriptomic analysis was subsequently conducted. Zinc metabolism scores were acquired through single-sample Gene Set Enrichment Analysis algorithms. Stromal scores were obtained using the R Package "estimate" algorithms. Important Kyoto Encyclopedia of Genes and Genomes and Gene Ontology pathways were also derived through gene set variation analysis. Cytoscape software helped construct the transcription factor (TF)-mRNA-microRNA (miRNA) network. Virtual screening and molecular docking were performed. Polymerase chain reaction validation was also carried out in vivo. Causal relationships were demonstrated between zinc and exercise (95% confidence interval [CI] = 1.30-2.95, p = 0.001), exercise and immunity (95% CI = 0.36-0.80, p = 0.002), exercise and osteoporosis (95% CI = 0.97-0.99, p = 0.0007), and immunity disorder and osteoporosis (95% CI = 1.30-2.03, p = 0.00002). One hundred and seventy-nine mRNAs in important modules were screened. Combining the differential expressional genes (DEGs) and the Boruta selection, six DEGs were screened (AHNAK, CSF2, ADAMTS12, SRA1, RUNX2, and SLC39A14). TF HOXC10 and miRNA hsa-miR-204 were predicted. Then, the TF-mRNA-miRNA network was successfully constructed. RUNX2 and SLC39A14 were identified as hub mRNAs in the TF-mRNA-miRNA network. Eventually, the novel small drug C6O4NH5 was designed according to the pharmacophore structure of SLC39A14. The docking energy for the novel drug was -5.83 kcal/mol. SLC39A14 and RUNX2 were downregulated (of statistical significance p-value < 0.05) in our animal experiment. This study revealed that zinc had a protective causal relationship with disuse osteoporosis by promoting exercise and immunity. SLC39A14 and RUNX2 mRNA participated in this zinc-related mechanism.

Strontium chloride improves bone mass by affecting the gut microbiota in young male rats.

Bone mass accumulated in early adulthood is an important determinant of bone mass throughout the lifespan, and inadequate bone deposition may lead to associated skeletal diseases. Recent studies suggest that gut bacteria may be potential factors in boosting bone mass. Strontium (Sr) as a key bioactive element has been shown to improve bone quality, but the precise way that maintains the equilibrium of the gut microbiome and bone health is still not well understood. We explored the capacity of SrCl2 solutions of varying concentrations (0, 100, 200 and 400 mg/kg BW) on bone quality in 7-week-old male Wistar rats and attempted to elucidate the mechanism through gut microbes. The results showed that in a Wistar rat model under normal growth conditions, serum Ca levels increased after Sr-treatment and showed a dose-dependent increase with Sr concentration. Three-point mechanics and Micro-CT results showed that Sr exposure enhanced bone biomechanical properties and improved bone microarchitecture. In addition, the osteoblast gene markers BMP, BGP, RUNX2, OPG and ALP mRNA levels were significantly increased to varying degrees after Sr treatment, and the osteoclast markers RANKL and TRAP were accompanied by varying degrees of reduction. These experimental results show that Sr improves bones from multiple angles. Further investigation of the microbial population revealed that the composition of the gut microbiome was changed due to Sr, with the abundance of 6 of the bacteria showing a different dose dependence with Sr concentration than the control group. To investigate whether alterations in bacterial flora were responsible for the effects of Sr on bone remodeling, a further pearson correlation analysis was done, 4 types of bacteria (Ruminococcaceae_UCG-014, Lachnospiraceae_NK4A136_group, Alistipes and Weissella) were deduced to be the primary contributors to Sr-relieved bone loss. Of these, we focused our analysis on the most firmly associated Ruminococcaceae_UCG-014. To summarize, our current research explores changes in bone mass following Sr intervention in young individuals, and the connection between Sr-altered intestinal flora and potentially beneficial bacteria in the attenuation of bone loss. These discoveries underscore the importance of the "gut-bone" axis, contributing to an understanding of how Sr affects bone quality, and providing a fresh idea for bone mass accumulation in young individuals and thereby preventing disease due to acquired bone mass deficiency.

Osteoinductive effect β-TCP and vitamin D3 on RUNX2 mRNA expression

Although the autograft is regarded as the gold standard bone graft, β-TCP artificial alloplastic is widely used in bone defect healing and has been accepted in human and animal studies to be resorbed and interchanged by vital bone. The active form of vitamin D3 is calcitriol, on mesenchymal stem cells (MSCs) it has a direct influence on encouraging their osteogenic differentiation which is identified as osteoinductive. The need for osteoinductive ability is a demanding issue regarding medical and dental care. RUNX2 regards an essential transcriptional factor for osteoblast differentiation. Adult male New Zealand rabbits (Twenty-four) with an average weight of (1.5-2 kg) were elected in this study. Four holes were made intra-bone in both tibias of each animal. The experimental groups divide as follows: Group C: Bone defect will be left to heal naturally as control; Group TCP: Bone defect will be occupied with β-TCP. Group vitamin D3: Bone defect will be filled with vitamin D3; Group TCPD: Bone defect will be filled with a combination of β-TCP and vitamin D3. Animals sacrificed at (1 and 3 weeks). Purification of total RNA from formalin fixed paraffin embedded (FFPE), The cDNA of RUNX2 and VDR amplify in RT-PCR and detected with sybr green. One-way Analysis of Variance (ANOVA) and least significant difference (LSD) was used as a tool for statistical analysis. Results at 7 days highest mean value of mRNA RUNX2 gene expression Fold Change estimated in TCP followed by TCPD experimental group while at 21 days, the highest mean value in TCPD. All measured parameters showed highly significant differences in the course of healing periods from 7 days to 21 days. In mRNA VDR gene expression parameters showed a highly significant difference in 7days and 21 days durations among experimental groups and the highest mean value of mRNA VDR gene expression Fold Change is recorded in TCPD followed by vitamin D3 groups in both durations. These findings suggest positive inductive effects of local application of vitamin D3 combined with β-TCP as well as vitamin D3 on osteoblast cells and induced bone defect healing.

A novel CircRNA Circ_0001722 regulates proliferation and invasion of osteosarcoma cells through targeting miR-204-5p/RUNX2 axis

BackgroundOsteosarcoma (OS) is the most prevalent primary fatal bone neoplasm in adolescents and children owing to limited therapeutic methods. Circular RNAs (circRNAs) are identified as vital regulators in a variety of cancers. However, the roles of circRNAs in OS are still unclear.MethodsFirstly, we evaluate the differentially expressed circRNAs in 3 paired OS and corresponding adjacent nontumor tissue samples by circRNA microarray assay, finding a novel circRNA, circ_001722, significantly upregulated in OS tissues and cells. The circular structure of candidate circRNA was confirmed through Sanger sequencing, divergent primer PCR, and RNase R treatments. Proliferation of OS cells was evaluated in vitro and in vivo. The microRNA (miRNA) sponge mechanism of circRNAs was verified by dual-luciferase assay and RNA immunoprecipitation assay.ResultsA novel circRNA, circ_001722, is significantly upregulated in OS tissues and cells. Downregulation of circ_0001722 can suppress proliferation and invasion of human OS cells in vitro and in vivo. Computational algorithms predict miR-204-5p can bind with circ_0001722 and RUNX2 mRNA 3’UTR, which is verified by Dual-luciferase assay and RNA immunoprecipitation assay. Further functional experiments show that circ_0001722 competitively binds to miR-204-5p and prevents it to decrease the level of RUNX2, which upregulates proliferation and invasion of human OS cells.ConclusionCirc_001722 is a novel tumor promotor in OS, and promotes the progression of OS via miR-204-5p/RUNX2 axis.

Sema3A Modified PDLSCs Exhibited Enhanced Osteogenic Capabilities and Stimulated Differentiation of Pre-Osteoblasts.

Genetically engineered stem cells, not only acting as vector delivering growth factors or cytokines but also exhibiting improved cell properties, are promising cells for periodontal tissue regeneration. Sema3A is a power secretory osteoprotective factor. In this study, we aimed to construct Sema3A modified periodontal ligament stem cells (PDLSCs) and evaluated their osteogenic capability and crosstalk with pre-osteoblasts MC3T3-E1. First, Sema3A modified PDLSCs was constructed using lentivirus infection system carrying Sema3A gene and the transduction efficiency was analyzed. The osteogenic differentiation and proliferation of Sema3A-PDLSCs was evaluated. Then, MC3T3-E1 was directly co-cultured with Sema3A-PDLSCs or cultured in condition medium of Sema3A-PDLSCs and the osteogenic ability of MC3T3-E1 was assessed. The results showed that Sema3A-PDLSCs expressed and secreted upregulated Sema3A protein, which confirmed successful construction of Sema3A modified PDLSCs. After osteogenic induction, Sema3A-PDLSCs expressed upregulated ALP, OCN, RUNX2, and SP7 mRNA, expressed higher ALP activity, and produced more mineralization nodes, compared with Vector-PDLSCs. Whereas, there was no obvious differences in proliferation between Sema3A-PDLSCs and Vector-PDLSCs. MC3T3-E1 expressed upregulated mRNA of ALP, OCN, RUNX2, and SP7 when directly co-cultured with Sema3A-PDLSCs than Vector-PDLSCs. MC3T3-E1 also expressed upregulated osteogenic markers, showed higher ALP activity, and produced more mineralization nodes when cultured using condition medium of Sema3A-PDLSCs instead of Vector-PDLSCs. In conclusion, our results indicated that Sema3A modified PDLSCs showed enhanced osteogenic capability, and also facilitated differentiation of pre-osteoblasts.

Enhancement of bone regeneration by coadministration of angiogenic and osteogenic factors using messenger RNA

BackgroundBone defects remain a challenge today. In addition to osteogenic activation, the crucial role of angiogenesis has also gained attention. In particular, vascular endothelial growth factor (VEGF) is likely to play a significant role in bone regeneration, not only to restore blood supply but also to be directly involved in the osteogenic differentiation of mesenchymal stem cells. In this study, to produce additive angiogenic-osteogenic effects in the process of bone regeneration, VEGF and Runt-related transcription factor 2 (Runx2), an essential transcription factor for osteogenic differentiation, were coadministered with messenger RNAs (mRNAs) to bone defects in the rat mandible.MethodsThe mRNAs encoding VEGF or Runx2 were prepared via in vitro transcription (IVT). Osteogenic differentiation after mRNA transfection was evaluated using primary osteoblast-like cells, followed by an evaluation of the gene expression levels of osteogenic markers. The mRNAs were then administered to a bone defect prepared in the rat mandible using our original cationic polymer-based carrier, the polyplex nanomicelle. The bone regeneration was evaluated by micro-computerized tomography (μCT) imaging, and histologic analyses.ResultsOsteogenic markers such as osteocalcin (Ocn) and osteopontin (Opn) were significantly upregulated after mRNA transfection. VEGF mRNA was revealed to have a distinct osteoblastic function similar to that of Runx2 mRNA, and the combined use of the two mRNAs resulted in further upregulation of the markers. After in vivo administration into the bone defect, the two mRNAs induced significant enhancement of bone regeneration with increased bone mineralization. Histological analyses using antibodies against the Cluster of Differentiation 31 protein (CD31), alkaline phosphatase (ALP), or OCN revealed that the mRNAs induced the upregulation of osteogenic markers in the defect, together with increased vessel formation, leading to rapid bone formation.ConclusionsThese results demonstrate the feasibility of using mRNA medicines to introduce various therapeutic factors, including transcription factors, into target sites. This study provides valuable information for the development of mRNA therapeutics for tissue engineering.

#4000 ROLE OF ENDOTHELIAL CELLS IN VASCULAR CALCIFICATION

Abstract Background and Aims Vascular calcification (VC) represents a common pathological feature of cardiovascular disease and VC caused by hyperphosphatemia is one of the hallmarks of chronic kidney disease (CKD). Therefore, elucidating the pathogenesis of VC may have significant clinical benefits for CKD patients. Vascular smooth muscle cells challenged with high-phosphate (Pi) actively participate to VC by trans-differentiating into simil-osteoblastic cells that acquire the capability to deposit hydroxyapatite crystals in the extracellular matrix of tunica media in arteries. The role of endothelial cells (ECs) in high-Pi calcification has been poorly investigated until now. Nonetheless, following particular stimuli ECs can lose their endothelial characteristics and acquire several different phenotypes transdifferentiating with a process known as endothelial-to-mesenchymal transition (EndMT). Given the central role of VC for CKD patients wellbeing we decided to investigate whether ECs may have a role in VC process. Method We set up an in vitro calcification model with human aortic ECs (HAECs) challenged with 2, 2.5, 3, 3.5 mM high-Pi for 7 days. Calcium deposition, cell viability and cell trans-differentiation were evaluated. Results In our model we observed deposition of calcium phosphate crystals induced by high-Pi that resulted significant from 3 up to 3.5 mM Pi (Ctr 0.43 ± 0.01; 3 mM Pi 6.72 ± 1.15; 3.5 mM Pi 17.31 ± 1.88; micromol Ca++/mg protein; P &amp;lt; .01; Fig 1A-B). We found that calcification is mediated by Pi-influx, as demonstrated by the inhibition of calcium deposition by Phosphonoformic acid (PFA), an inhibitor of Na/Pi cotransporter Pit-1 (3.5 mM Pi 15.52 ± 1.97; 1 mM PFA 0.6 ± 0.05; micromol Ca++/mg protein; P &amp;lt; .0001; Fig 1A, C). In addition, in our model high-Pi did not show any significant toxic effect at every concentration tested compared to control cells. In Pi-treated ECs we observed a clear change in cell-morphology from cobblestone to spindle shaped, a recognized sign of EndMT. Moreover, we observed a change in extracellular matrix composition more similar to osteoblastic matrix. In facts, ECs treated with Pi were Alcian Blue positive, a staining that binds glycosaminoglycans contained in bone matrix, with blue granules of calcium-phosphate in the cytoplasm of treated cells. Starting from day 5 up to day 7 the transition was confirmed by an up-regulation of SNAIL and N-cadherin mRNA expressions, one of the master genes and one the markers of EndMT process, respectively. A modification of endothelial phenotype was also supported by a progressive decrease in protein expression of Von Willebrand factor and VE-Cadherin observed at day 9 of calcification (−53.7% and −32.6% respectively). Moreover, from day 5 till day 7 we found some osteoblastic differentiation signs such as a progressive increase of RUNX2 and BMP2 mRNA expression and an increase of protective MGP mRNA levels. Conclusion Our data demonstrate that HAECs are able to calcify. High-Pi induces trans-differentiation in simil-osteoblastic cells and a progressive loss of endothelial characteristics through the EndMT process. More studies are needed to better elucidate the role for ECs in CKD VC process.

IL-6-induced response of human osteoblasts from patients with rheumatoid arthritis after inhibition of the signaling pathway.

Interleukin (IL-) 6 is a critical factor in inflammatory processes of rheumatoid arthritis (RA). This is of high interest as the progression of RA may lead to the implantation of joint endoprostheses, which is associated with a pro-inflammatory increase in IL-6 in the periprosthetic tissue. Biological agents such as sarilumab have been developed to inhibit IL-6-mediated signaling. However, IL-6 signaling blockade should consider the inhibition of inflammatory processes and the regenerative functions of IL-6. This in vitro study investigated whether inhibiting IL-6 receptors can affect the differentiation of osteoblasts isolated from patients with RA. Since wear particles can be generated at the articular surfaces of endoprostheses leading to osteolysis and implant loosening, the potential of sarilumab to inhibit wear particle-induced pro-inflammatory processes should be investigated. Both in monocultures and indirect co-cultures with osteoclast-like cells (OLCs), human osteoblasts were stimulated with 50ng/mL each of IL-6 + sIL-6R and in combination with sarilumab (250nM) to characterize cell viability and osteogenic differentiation capacity. Furthermore, the influence of IL-6 + sIL-6R or sarilumab on viability, differentiation, and inflammation was evaluated in osteoblasts exposed to particles. Stimulation with IL-6 + sIL-6R and sarilumab did not affect cell viability. Except for the significant induction of RUNX2 mRNA by IL-6 + sIL-6R and a significant reduction with sarilumab, no effects on cell differentiation and mineralization could be detected. Furthermore, the different stimulations did not affect the osteogenic and osteoclastic differentiation of co-cultured cells. Compared to the osteoblastic monocultures, a decreased release of IL-8 was triggered in the co-culture. Among these, treatment with sarilumab alone resulted in the greatest reduction of IL-8. The co-culture also showed clearly increased OPN concentrations than the respective monocultures, with OPN secretion apparently triggered by the OLCs. Particle exposure demonstrated decreased osteogenic differentiation using different treatment strategies. However, sarilumab administration caused a trend toward a decrease in IL-8 production after stimulation with IL-6 + sIL-6R. The blockade of IL-6 and its pathway have no significant effect on the osteogenic and osteoclastic differentiation of bone cells derived from patients with RA. Nonetheless, observed effects on the reduced IL-8 secretion need further investigation.

PUF: A potential repressor of oncogenes.

e15095 Background: RNA-binding proteins (RBPs) play a crucial role in orchestrating the function of RNAs. The regulation of RBPs is critical in various biological processes, including tumorigenesis. The PUF (Pumilio/FBF) RBPs are of particular interest due to their function in stem cells and tumor-initiating cells. Its has been shown that PUF proteins inhibit the translation of target genes by binding to a regulatory element (PBE) in the 3’ untranslated regions (3’UTRs) of their target mRNA. PUF proteins are required to maintain normal stem cells and potentially inhibit the formation of tumor-initiating cells by repressing the expression of oncogenes. Bioinformatics analysis has identified many oncogenes as potential targets of PUF, and pilot studies have confirmed that ERK, p38, JAK2, RUNX2, and RET mRNAs specifically interact with PUF protein. The objective of this study is to investigate the function of human PUF proteins in the initiation and progression of cancer cells. Methods: In worms (C. elegans), 100 % PUF mutants form tumors. Bioinformatics were performed to identify PUF target genes, it specifically binds UGUAnAUA sequences on target mRNA 3'UTRs. Yeast three-hybrid assay were performed to test the physical interaction between PUF protein and its target mRNA. The novel function of human PUF proteins in the initiation and progression of cancer cells was investigated using CRISPR/Cas9 knockout cancer cell lines and western Blot/IHC was done to determine their expression. Results: The results of the study showed that PUF proteins play a crucial role in inhibiting the formation of tumor-initiating cells. Loss of PUF function and activation of ERK signaling were found to promote the formation of these cells. Bioinformatics analysis revealed that many oncogenes are potential targets for PUF repression. The study also demonstrated that PUF represses the expression of ERK and p38 mRNAs via their 3’UTRs. These findings suggest that PUF may have therapeutic potential as a target for cancer treatment. Conclusions: In worms and human cells, normal PUF proteins promote the cell proliferation of stem cells, however, stem cells begin to differentiate, PUF proteins are required to complete differentiation. Therefore, in the differentiating cells, PUF mutation cannot complete differentiation, instead, return to undifferentiating cells, resulting in tumors. Bioinformatics and biochemical analyses revealed that many PUF repressing targets (~ &gt; 30%) are oncogene and some labs including us found that PUF knockdown enhanced oncogene expression. PUF can be a potential biomarker, as low PUF expression may initiate tumors. Therapeutically, conditional PUF expression in tumor-initiating cells may suppress tumor progression by suppressing oncogene.

Indoxyl-sulfate activation of the AhR-NFκB pathway promotes IL-6 secretion and subsequent osteogenic differentiation in human valvular interstitial cells

Calcific aortic valve disease (CAVD) results from fibro-calcific degeneration of the aortic valve leaflets, causing major cardiovascular complications. In chronic kidney disease (CKD) patients, this pathological remodelling is more frequent, appears earlier and progresses faster leading to a mortality rate three times higher than in the general population. The uremic toxin Indoxyl-sulfate (IS), a powerful predictor of cardiovascular mortality in CKD patients, is a strong promoter of ectopic calcification, which role in CAVD has never been studied. This work aimed to evaluate whether IS influences primary human valvular interstitial cells (hVICs) mineralization in-vitro. Primary hVICs isolated from aortic tricuspid valves collected from CAVD patients were exposed to increasing concentrations of IS (IS normal [Isn]: 0.5 Mg/mL, IS uremic [Isu]: 37 Mg/mL or IS maximum [Ismax]: 233 Mg/mL) in the presence of an osteogenic medium (OM) containing 2.4 mmol/L calcium and 2.5 mmol/L phosphate. HVICs osteogenic transition was assessed by qRT-PCR following Bmp2 and Runx2 mRNA. Their mineralization was quantified by the o-cresolphthalein method. Inflammation was assessed following NFκB activation by western blot and IL-1β, IL-6 and TNF-α secretion by ELISA. A siRNA approach allowed determining the signaling pathway involved. IS increased OM-induced hVICs osteogenic transition and calcification concentration-dependently, an effect blocked after transfection with siRNA targeting IS receptor AhR. Exposure to [ISu] or [ISmax] promoted P65 phosphorylation, the blockade of which inhibited IS-induced mineralization, suggesting a key role for inflammation in this process. HVICs did not secrete TNF-α, produced few IL-1β but secreted high amounts of IL-6 in response to IS, which was blocked by silencing AhR or P65. The use of an antibody neutralizing IL-6 abolished IS-induced procalcific effects. IS promotes hVICs mineralization through AhR-dependent activation of NFκB pathway and subsequent release of IL-6. The fact that IL-6 neutralization blocks IS procalcific effects is of particular interest since interventional studies evaluating the cardiovascular impact of anti-IL-6 antibodies in CKD are underway.

Panax quinquefolius saponin inhibits vascular smooth muscle cell calcification via activation of nuclear factor-erythroid 2-related factor 2

BackgroundPanax quinquefolius saponin (PQS) is the main active component of Panax quinquefolius. Emerging evidence suggests that PQS exerts beneficial effects against cardiovascular diseases. However, the role and mechanism of PQS in vascular calcification are not unclear. The present study investigated the effects of PQS on the calcification of vascular smooth muscle cell (VSMCs).MethodsThe present study used calcification medium containing 3 mM inorganic phosphate (Pi) to induce rat VSMCs calcification. We investigated the effects of PQS on VSMCs calcification using alizarin red staining and alkaline phosphatase (ALP) activity assays. The intracellular reactive oxygen species (ROS) levels and the transcriptional activity of nuclear factor-erythroid 2-related factor 2 (Nrf2) were determined. The mRNA and protein expression levels of Nrf2, the antioxidant gene heme oxygenase-1 (HO-1), osteogenic markers, including runt-related transcription factor 2 (Runx2) and bone morphogenetic protein 2 (BMP2), and Kelch-like ECH-associated protein 1 (Keap1) were also measured.ResultsTreatment with Pi significantly increased intracellular calcium deposition and ALP activity, which were suppressed by PQS in a concentration-dependent manner. During VSMCs calcification, PQS inhibited the mRNA and protein expression of Runx2 and BMP2. PQS treatment reduced intracellular ROS production and significantly upregulated Nrf2 transcriptional activity and the expression of Nrf2 and its target antioxidant gene HO-1. PQS suppressed the Pi-induced protein expression of Keap1, which is an endogenous inhibitor of Nrf2. Keap1 siRNA treatment induced Nrf2 expression and downregulated Runx2 expression in the presence of Pi and PQS.ConclusionTaken together, these findings suggest that PQS could effectively inhibit VSMCs calcification by ameliorating oxidative stress and regulating osteogenic genes via the promotion of Nrf2 expression.

Role of p53 in promoting BMP9‑induced osteogenic differentiation of mesenchymal stem cells through TGF‑β1.

Known as a tumour suppressor gene, p53 also plays a key role in controlling the differentiation of mesenchymal stem cells (MSCs). Bone morphogenetic protein 9 (BMP9) has been identified as a potent factor in inducing osteogenic differentiation of MSCs, but its relationship with p53 remains unclear. The present study revealed that TP53 was expressed at higher levels in MSCs from patients with osteoporosis and was associated with the top 10 core central genes found in the current osteoporosis genetic screen. p53 was expressed in C2C12, C3H10T1/2, 3T3-L1, MEFs, and MG-63 cell lines, and could be upregulated by BMP9, as measured by western blotting and reverse-transcription quantitative PCR (RT-qPCR). Furthermore, overexpression of p53 increased the mRNA and protein levels of osteogenic marker Runx2 and osteopontin, as evaluated by western blotting and RT-qPCR in BMP9-induced MSCs, whereas the p53 inhibitor pifithrin (PFT)-α attenuated these effects. The same trend was found in alkaline phosphatase activities and matrix mineralization, as measured by alkaline phosphatase staining and alizarin red S staining. Moreover, p53 overexpression reduced adipo-differentiation markers of PPARγ and lipid droplet formation, as measured by western blotting, RT-qPCR and oil red O staining, respectively, whereas PFT-α facilitated adipo-differentiation in MSCs. In addition, p53 promoted TGF-β1 expression and inhibition of TGF-β1 by LY364947 partially attenuated the effects of p53 on promoting BMP9-induced MSC osteo-differentiation and inhibiting adipo-differentiation. The inhibitory effect of PFT-α on osteogenic markers and the promoting effect on adipogenic markers can be reversed when combined with TGF-β1. TGF-β1 may enhance the promotion of osteo-differentiation of MSCs by p53 through inhibition of adipo-differentiation. Collectively, by promoting BMP9-induced MSCs bone differentiation and inhibiting adipose differentiation, p53 may be a novel therapeutic target for bone-related diseases.

MiR-20a promotes osteogenic differentiation in bone marrow-derived mesenchymal stem/stromal cells and bone repair of the maxillary sinus defect model in rabbits.

Introduction: This study aimed to determine whether miR-20 promoted osteogenic differentiation in bone marrow-derived mesenchymal stem/stromal cells (BMSCs) and accelerated bone formation in the maxillary sinus bone defect model in rabbits. Methods: BMSCs were transfected with miR-20a or anti-miR-20a for 12h, followed by detection of RUNX2, Sp7 mRNA, bone morphogenetic protein 2 (BMP2), and RUNX2 protein expression. Alkaline phosphatase (ALP) activity and Alizarin Red S staining were used to detect calcified nodule deposition. In the rabbit maxillary sinus bone defect model, miR-20a loaded with AAV and BMP2 protein were mixed with Bio-Oss bone powder for filling the bone defect. At 4weeks and 8weeks, bone density was detected by cone beam computed tomography (CBCT), and new bone, osteoblasts, and collagen type 1 were evaluated by hematoxylin and eosin (HE) staining and immunohistochemical (IHC) staining. Results: Overexpression of miR-20a enhanced the mRNA and protein levels of BMP2, RUNX2, and SP7, the activity of ALP, and the levels of matrix mineralization, whereas the levels and activity of the aforementioned factors were decreased by anti-miR-20a treatment of BMSCs. Furthermore, miR-20a significantly increased the bone density, the number of osteoblasts, and the secretion of collagen type 1 in bone defects compared with Bio-Oss bone powder in the rabbit maxillary sinus bone defect model. Conclusion: Overall, miR-20a can induce osteogenic differentiation in BMSCs and accelerate bone formation of maxillary sinus defects in rabbits.

Indoxyl-sulfate activation of the AhR- NF-κB pathway promotes interleukin-6 secretion and the subsequent osteogenic differentiation of human valvular interstitial cells from the aortic valve

Calcific aortic stenosis (CAS) is more prevalent, occurs earlier, progresses faster and has worse outcomes in patients with chronic kidney disease (CKD). The uremic toxin indoxyl sulfate (IS) is powerful predictor of cardiovascular mortality in these patients and a strong promoter of ectopic calcification whose role in CAS remains poorly studied. The objective of this study was to evaluate whether IS influences the mineralization of primary human valvular interstitial cells (hVICs) from the aortic valve. Primary hVICs were exposed to increasing concentrations of IS in osteogenic medium (OM). The hVICs' osteogenic transition was monitored by qRT-PCRs for BMP2 and RUNX2 mRNA. Cell mineralization was assayed using the o-cresolphthalein complexone method. Inflammation was assessed by monitoring NF-κB activation using Western blots as well as IL-1β, IL-6 and TNF-α secretion by ELISAs. Small interfering RNA (siRNA) approaches enabled us to determine which signaling pathways were involved. Indoxyl-sulfate increased OM-induced hVICs osteogenic transition and calcification in a concentration-dependent manner. This effect was blocked by silencing the receptor for IS (the aryl hydrocarbon receptor, AhR). Exposure to IS promoted p65 phosphorylation, the blockade of which inhibited IS-induced mineralization. Exposure to IS promoted IL-6 secretion by hVICs, a phenomenon blocked by silencing AhR or p65. Incubation with an anti-IL-6 antibody neutralized IS's pro-calcific effects. IS promotes hVIC mineralization through AhR-dependent activation of the NF-κB pathway and the subsequent release of IL-6. Further research should seek to determine whether targeting inflammatory pathways can reduce the onset and progression of CKD-related CAS.

Basal and inducible Osterix expression reflect equine mesenchymal progenitor cell osteogenic capacity.

Mesenchymal stem cells are characterized by their capacities for extensive proliferation through multiple passages and, classically, tri-lineage differentiation along osteogenic, chondrogenic and adipogenic lineages. This study was carried out to compare osteogenesis in equine bone marrow-, synovium- and adipose-derived cells, and to determine whether osteogenic capacity is reflected in the basal expression of the critical osteogenic transcription factors Runx2 and Osterix. Bone marrow, synovium and adipose tissue was collected from six healthy 2-year-old horses. Cells were isolated from these sources and expanded through two passages. Basal expression of Runx2 and Osterix was assessed in undifferentiated third passage cells, along with their response to osteogenic culture conditions. Bone marrow-derived cells had significantly higher basal expression of Osterix, but not Runx2. In osteogenic medium, bone-marrow cells rapidly developed dense, multicellular aggregates that stained strongly for mineral and alkaline phosphatase activity. Synovial and adipose cell cultures showed far less matrix mineralization. Bone marrow cells significantly up-regulated alkaline phosphatase mRNA expression and enzymatic activity at 7 and 14 days. Alkaline phosphatase expression and activity were increased in adipose cultures after 14 days, although these values were less than in bone marrow cultures. There was no change in alkaline phosphatase in synovial cultures. In osteogenic medium, bone marrow cultures increased both Runx2 and Osterix mRNA expression significantly at 7 and 14 days. Expression of both transcription factors did not change in synovial or adipose cultures. These results demonstrate that basal Osterix expression differs significantly in progenitor cells derived from different tissue sources and reflects the osteogenic potential of the cell populations.