Osteoblast Differentiation Pathway Research Articles

Naringin-induced M2 macrophage polarization facilitates osteogenesis of BMSCs and improves cranial bone defect healing in rat

Osteoimmunology has uncovered the critical role of the immune microenvironment in the bone healing process, with macrophages playing a central part in generating immune responses via chemokine production. Naringin, a flavanone glycoside extracted from various plants, has been shown to promote osteoblast differentiation, thereby enhancing bone formation and mitigating osteoporosis progression. Current research on the osteogenic mechanism primarily focuses on the direct impact of naringin on mesenchymal stem cells, while its indirect immunoregulatory effects remain elusive. In this study, we investigated the bone defect-enhancing effects of varying naringin concentrations in vivo using a cranial bone defect model in Sprague-Dawley rats. We assessed the osteoimmune modulation capacity of naringin by exposing lipopolysaccharide (LPS)-induced RAW 264.7 macrophages to different doses of naringin. To further elucidate the underlying osteogenic enhancement mechanism, Bone Marrow Stromal Cells (BMSCs) derived from mice were treated with conditioned media from naringin-treated macrophages. Our findings indicated that naringin promotes M2 phenotype polarization in macrophages, as evidenced by the downregulation of pro-inflammatory cytokines Inducible Nitric Oxide Synthase (iNOS), interleukin (IL)-1β, and Tumor Necrosis Factor (TNF)-α, and the upregulation of anti-inflammatory cytokine Transforming growth factor (TGF)-β. Transcriptome analysis revealed that differentially expressed genes were significantly enriched in osteoblast differentiation and anti-inflammatory response pathways in naringin-pretreated macrophages, with the cytokines signaling pathway being upregulated. The conditioned media from naringin-treated macrophages stimulated the expression of osteogenic-related genes Alkaline phosphatase (Alp), osteocalcin (Ocn), osteopontin (Opn), and Runt-related transcription factor (Runx) 2, as well as protein expression in BMSCs. In conclusion, naringin alleviates macrophage inflammation by promoting M2 phenotype polarization, which in turn enhances the osteogenic differentiation of BMSCs, contributing to its bone healing effects in vivo. These results suggest that naringin holds significant potential for improving bone defect healing through osteoimmune modulation.

Abstract P3168: Identification Of Exosome MicroRNA In Association With Severe Calcification In Coronary Chronic Total Occlusion

Backgrounds: Coronary artery calcification (CAC) is prevalent in patients with coronary chronic total occlusion (CTO). We investigated the association between plasma miRNAs and coronary artery calcification in patients with CTO. Methods: Blood samples were collected from 18 patients who underwent percutaneous coronary intervention (PCI) of CTO. Exosomal small RNA sequencing was performed from plasma to quantify miRNA expression. Calcium volume was quantified in computed tomography (CT) in CTO. Gene ontology and functional pathway were analyzed in the miRNAs that significantly correlates with calcium volume. Results: Calcium volume was positively correlated with miR-1-3p and miR-708-3p (p <0.05), and was negatively correlated with 4 miRNAs -including let-7d-5p (p <0.05). Gene enrichment and pathway analysis showed that the target genes of the 2 positively correlated miRNAs were involved in regulation of osteoblast differentiation and osteopontin signaling pathway. In contrast, the target genes of the 4 negatively correlated miRNAs were enriched in acetylcholine-mediated vasodilation involved in regulation of systemic arterial blood pressure, blood vessel development and response to sterol. Multiple linear regression showed that miR-1-3p and let-7d-5p could be key predictors of the calcium volume of CTO (adjusted R 2 = 0.798 and p <0.001). Conclusions: We identified miR-1-3p and let-7d-5p could be related with CAC in patients with CTO.

Identification of key miRNAs in unilateral mastication-induced disruption of cartilage homeostasis.

The present study identified potentially pivotal miRNAs contributing to chondrogenic differentiation in temporomandibular joint suffering abnormal stress. Sprague-Dawley rats were randomly divided into control and experimental unilateral mastication (EUM) group. Bone micro-structure parameters was detected by micro-CT, and FGF-1 and MMP-1 expression was examined by immunohistochemistry. Differentially expressed miRNAs of bilateral condyle cartilage were screened via miRNA microarray at 4- and 8-week EUM, then further verified using quantitative reverse-transcription PCR. Over-expression of five differentially expressed miRNAs in chondrocytes was triggered by transfecting miRNA mimics. The expression of MMP-13, Col-II, OPN, and Runx2 was verified by western blotting. Expressions of FGF-1 and MMP-1 in right condyles gradually increased from 2 to 6 weeks after EUM. A total of 20 differentially expressed miRNAs were regulated by EUM, which related to cell proliferation, invasion, and osteoblast differentiation pathways. The over-expression of miR-148a-3p and miR-1-3p led to down-regulation of Col-II, while MMP-13 and Runx2 were up-regulated by induction of hypotrophic differentiation or IL-1β stimulation. These findings suggested that miR-148a-3p and miR-1-3p promote chondrogenic differentiation. Several pivotal miRNAs were found to be related to chondrogenic differentiation, which provides novel insight into pathogenic mechanisms of cartilage homeostasis.

Comprehensive Analysis of Mesenchymal Cells from Myeloproliferative Neoplasm (MPN) Patients Reveals the Role of HOXB7 in Myelofibrosis Induction

Introduction: Despite the advances in the treatment of MPN, the disease remains incurable with little remission rates and evolution to AML or Myelofibrosis (MF). MPN pathogenesis has been extensively studied but the evolution to MF remains poorly understood. In this study, using multiomic and functional approaches we comprehensively characterized mesenchymal stromal cells (MSCs) from fibrotic MPN patients (F-MPN) and identified a novel potentially druggable axis involved in the fibrosis phenotype. Methods: We characterized MSCs expanded from 13 MF patients (WHO criteria) (F-MSC) and from 17 age-matched healthy controls. The expanded F-MSCs were analyzed by immunophenotyping, Luminex cytokine array, RNA-seq and ATAC-seq techniques. The findings were validated using RT-qPCR, ChIP and differentiation assays while functional in vitro assays leaned on the HS-5 cell line and knock-down assays. Results: Immunophenotyping of F-MSCs, showed a significant differential expression of MSC markers compared to controls (decrease of CD90, CD73, CD106, CD140a, increase of CD105, CD295). As expected in a fibrotic tissue, F-MSCs secreted higher levels of inflammatory cytokines such as IL-1a, IL-1b, IL-8, Lipocalin, Leptin, VEGF, PDGF, , IGFBP2 and TGF-B (p<0.05, (fig a). The transcriptomic analysis of F-MPN samples further confirmed their fibrotic phenotype with enrichment of genes associated with fibrosis in signaling pathways such as actin filament organization, TGF-B receptor and Wnt (GSEA) (fig b). RNA-Seq highlighted two novel correlated findings of F-MPN stroma. First: an enrichment for genes of the osteoblast differentiation (fig b&c), underscored by ATAC-seq pointing to an enrichment for osteoblast differentiation transcription factor motifs (RUNX2, SMAD, SP5), an increased accessibility for ACTA2 (fibrotic/osteoblast gene) and decreased accessibility for adipocyte (PPARG) and chondrocyte (SOX9) transcription factors (P<0.002) (fig d). In vitro differentiation confirmed the F-MPN stroma biased differentiation towards osteoblast differentiation with reduced adipocyte and chondrocyte differentiation (P=0.0001, fig e). Second, a gene not previously linked to MPN fibrosis, HOXB7, was identified among the top 20 highly deregulated genes (fig f); RT-qPCR confirmed the significant upregulation of HOXB7 in F-MPN samples (P=0.002, fig f). HOXB7 is known as the most relevant HOXB gene associated with osteoblast differentiation. To functionally link these two novel gene profiles (ie the increased osteoblast differentiation pathway and HOXB7 gene expression) functional analyses of TGF-B treated F-MSCs showed, along with the reported activation of the Wnt pathway (increase, stabilization and translocation to the nucleus of B-Catenin), an increased binding of B-catenin to the promoter of HOXB7 (ChIP assay) followed by increased expression of HOXB7 (P=0.05) (fig g). Finally, shRNA-mediated knockdown or incubation with inhibitors (Cardamonin or FZM1) against HOXB7 or Wnt signalling resulted in decreased expression of osteoblast/fibrosis target genes and reduced osteoblast differentiation (fig h & i). Conclusion: We identify a novel molecular and functional TGFB-WNT-HOXB7 activated axis in the development of a fibrotic phenotype. Invalidation studies demonstrated that this novel axis can be targeted which may counteract fibrotic evolution in MPN. Figure: a) Luminex analysis showing upregulation of inflammatory cytokines secreted from fibrotic MSC in comparison to control MSCs. b-c) GSEA plot of RNA-seq showing enrichment of fibrosis associated pathway and of osteoblast differentiation pathway. d) ATAC-seq motif analysis showing an enrichment of osteoblast associated transcription factors and RT-qPCR showing an upregulation of genes involved in osteoblast differentiation and fibrosis. e) Osteo and Adipo differentiation of expanded stroma: increased osteogenesis and decreased adipogenesis. f) Volcano plot showing differential gene expression in F-MSC: HOXB7 was validated using RT-qPCR. g) increased translocation of B-Catenin subunit in the nucleus of HS-5 cells upon TGF-B treatment and ChIP showing B-Catenin bound to the promoter of HOXB7 h) B-catenin or HOXB7 knock down resulted in reduction of fibrotic/osteoblast genes (ACTA2/a-SMA). i) HOXB7 knockdown in HS-5- cells led to reduced osteoblast differentiation compared to scrambled (SCR) shRNA. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Transcriptomic analysis of intermuscular bone development in barbel steed (Hemibarbus labeo)

Intermuscular bones (IBs), which are little, bony spicules in muscle, are embedded in lower teleosts' myosepta. Despite the importance of studying IB development in freshwater aquaculture species, the genes associated with IB development need to be further explored. In the present study, we identified four stages of IB development in barbel steed (Hemibarbus labeo), namely stage 1: IBs have not emerged, stage 2: a few small IBs have emerged in the tail, stage 3: longer IBs gradually emerged in the tail and stage 4: all of the IBs in the tail are mature and long, via Alizarin red staining. Subsequently, we used the HiseqXTen platform to sequence and de novo assemble the transcriptome of epaxial muscle (between 35th and 40th myomere) of barbel steed at 29 days (stage 1) and 42 days (stage 3) after hatching. A total of 190,814 unigenes were obtained with an average length and N50 of 648 bp and 1027 bp, respectively. We found 2174 differentially expressed genes (DEGs) between stages 1 and 3, of which 378 and 1796 were up- and down-regulated, respectively. Functional enrichment analysis showed that several DEGs functioned in ossification, positive regulation of osteoblast differentiation, osteoblast differentiation, and BMP signaling pathway, and were further enriched in signal pathway, including osteoclast differentiation, TGF-β signaling pathway, cytokine-cytokine receptor interaction, Jak-STAT signaling pathway, and other KEEG pathways. In conclusion, we identified genes that may be related to IB development, such as kazal type serine peptidase inhibitor domain 1 (KAZALD1), extracellular matrix protein 1 (ECM1), tetranectin, bone morphogenetic protein 1 (bmp1), acid phosphatase 5 (ACP5), collagen type XI alpha 1 chain (COL11A1), matrix metallopeptidase 9 (MMP9), pannexin-3 (PANX3), sp7 transcription factor (Sp7), and c-x-c motif chemokine ligand 8 (CXCL8), by comparing the transcriptomes of epaxial muscle before and after IB ossification. This study provided a theoretical basis for identifying the molecular mechanisms underlying IB development in fish.

Long-term osteogenic differentiation of human bone marrow stromal cells in simulated microgravity: novel proteins sighted

Microgravity-induced bone loss is a major concern for space travelers. Ground-based microgravity simulators are crucial to study the effect of microgravity exposure on biological systems and to address the limitations posed by restricted access to real space. In this work, for the first time, we adopt a multidisciplinary approach to characterize the morphological, biochemical, and molecular changes underlying the response of human bone marrow stromal cells to long-term simulated microgravity exposure during osteogenic differentiation. Our results show that osteogenic differentiation is reduced while energy metabolism is promoted. We found novel proteins were dysregulated under simulated microgravity, including CSC1-like protein, involved in the mechanotransduction of pressure signals, and PTPN11, SLC44A1 and MME which are involved in osteoblast differentiation pathways and which may become the focus of future translational projects. The investigation of cell proteome highlighted how simulated microgravity affects a relatively low number of proteins compared to time and/or osteogenic factors and has allowed us to reconstruct a hypothetical pipeline for cell response to simulated microgravity. Further investigation focused on the application of nanomaterials may help to increase understanding of how to treat or minimize the effects of microgravity.

Abstract B011: Two epigenetically distinct cellular states in osteosarcoma are regulated by a cluster-specific set of pioneer transcription factors

Abstract The Osteosarcoma (OS) genome is characterized by aneuploidy and dramatic structural rearrangements often leading to copy number gain and loss. There is significant heterogeneity between patients. Additionally, there is less known regarding the epigenetic heterogeneity within osteosarcoma and how this may impact critical phenotypes such as therapy response and metastasis. To characterize the osteosarcoma epigenome, we integrated ATAC-seq and RNA-seq across a unique set of patient samples, PDXs and PDX-derived cell lines obtained across the disease continuum and including biopsies, resections, and metastases. Assay for Transposase Accessible Chromatin with high-throughput sequencing (ATAC-seq) analysis revealed the presence of two distinct epigenetic cell states. Differential chromatin accessibility between the clusters showed ~3000 unique open regions per cluster. Using GREAT to associate the differential genomic regions to genes, the enriched pathways of Cluster 1 (C1) are related to mesenchymal cell proliferation, skeletal system morphogenesis, osteoblast differentiation, and Wnt signaling pathway, whereas Cluster 2 (C2) enriched pathways are related to cell motility and migration, extracellular matrix organization and regulation of protein serine/threonine kinase activity. Accessible regions in the chromatin were enriched for a unique set of transcription factor binding sites. C1 accessible regions are enriched with transcription factor binding motifs (TFBM) related to development including RUNX2/3, MEOX2, HOXA2/5, VAX1/2, MEF, VSX and DLX; whereas members of AP1 complex including FOSL1/2, c-FOS, JUN are TFBM enriched in open regions in C2. This is correlated with high protein expression of these transcription factors in a cluster-specific manner and differential binding to chromatin. As expected, gene expression showed a positive correlation with accessible regions in promoters. RUNX2 plays a major role in chromatin remodeling in C1, modifying the chromatin accessibility of 5300 regions, most located in &amp;lt;1kb from the promoters. In conclusion, we uncovered two epigenetically cell states regulated by a cluster-specific set of transcription factors which are able to remodel the chromatin. Citation Format: Eunice Lopez Fuentes, Andrew Clugston, Leanne C. Sayles, E. Alejandro Sweet-Cordero. Two epigenetically distinct cellular states in osteosarcoma are regulated by a cluster-specific set of pioneer transcription factors [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr B011.

Abstract IA026: Epigenetic and genomic features define distinct cellular states with possible therapeutic relevance in osteosarcoma

Abstract The Osteosarcoma (OS) genome is characterized by aneuploidy and dramatic structural rearrangements often leading to copy number gain and loss. Currently, all patients with osteoblastic OS at diagnosis are treated with the same highly toxic chemotherapy and no clinically relevant subtypes have been identified. While there is significant heterogeneity at the genome level between patients, less is known regarding epigenetic heterogeneity and how this may impact critical phenotypes such as therapy response and metastasis. To characterize the osteosarcoma epigenome, we integrated ATAC-seq and RNA-seq across a unique set of patient samples, PDXs and PDX-derived cell lines obtained across the disease continuum and including biopsies, resections, and metastasis. ATACseq analysis revealed the presence of two distinct epigenetic cell states (C1 and C2). Associating the differential genomic regions to likely regulated genes, the enriched pathways of Cluster 1 (C1) are related to mesenchymal cell proliferation, skeletal system morphogenesis, osteoblast differentiation, and Wnt signaling pathway. In contrast, Cluster 2 (C2) enriched pathways are related to cell motility and migration, extracellular matrix organization and regulation of protein serine/threonine kinase activity. Furthermore, accessible chromatin regions were enriched for a distinct set of transcription factor binding sites. We then assessed whether these epigenetic states were associated with response to targeted therapies. We identified unique vulnerability of C1 cell lines to AURK inhibitors whereas C2 cell lines had evidence for upregulation of MAPK and were vulnerable to treatment with trametinib. ATACseq analysis of PDX and a limited number of patient samples confirmed that these subtypes of OS also likely exist in patient tumors. In parallel to these studies, we have also carried out extensive additional analysis of vulnerability of OS cell ines to a wide range of targeted therapies. We find evidence for significant response to several inhibitors of the ATR-WEE1-CHK1 pathway nominating this as a potential novel vulnerability for OS. Therapeutic relevance of these findings is currently being explores in an orthotopic metastasis model of OS. Overall, our findings may define new subtypes of osteosarcoma with unique therapeutic vulnerabilities. Citation Format: E. Alejandro Sweet-Cordero. Epigenetic and genomic features define distinct cellular states with possible therapeutic relevance in osteosarcoma [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr IA026.

RANKL biology.

Since the receptor activator of nuclear factor-kappa B ligand (RANKL), its cognate receptor activator of nuclear factor-kappa B (RANK), and the decoy receptor osteoprotegerin (OPG) were discovered, a number of studies have uncovered the crucial role of the RANKL-RANK-OPG pathway in controlling the key aspect of bone homeostasis, the immune system, inflammation, cancer, and other systems under pathophysiological condition. These findings have expanded the understanding of the multifunctional biology of the RANKL-RANK-OPG pathway and led to the development of therapeutic potential targeting this pathway. The successful development and application of anti-RANKL antibody in treating diseases causing bone loss validates the utility of therapeutic approaches based on the modulation of this pathway. Moreover, recent studies have demonstrated the involvement of the RANKL-RANK pathway in osteoblast differentiation and bone formation, shedding light on the RANKL-RANK dual signaling in coupling bone resorption and bone formation. In this review, we will summarize the current understanding of the RANKL-RANK-OPG system in the context of the bone and the immune system as well as the impact of this pathway in disease conditions, including cancer development and metastasis.

Early life vitamin D depletion and mechanical loading determine methylation changes in the RUNX2, RXRA, and osterix promoters in mice

BackgroundEarly life vitamin D exposure is linked to later skeletal health with maternal vitamin D status in pregnancy associated with neonatal bone mass. The MAVIDOS study has demonstrated that vitamin D supplementation leads to reduced RXRA DNA methylation. Mice exposed to early life vitamin D deficiency have reduced bone mass and bone accrual in response to mechanical loading. Using the tibiae of these mice, we have examined the effect of diet and mechanical loading on the DNA methylation of promoters of genetic loci important for bone growth and development and their association with bone strength.ResultsMechanical loading of mouse tibiae leads to a reduction of RXRA DNA methylation. Early life vitamin D deficiency is associated with altered methylation of osterix and Runx2 in these bones. Tibia strength was also demonstrated to be associated with a change in DNA methylation status in CpGs of the vitamin D receptor (VDR), ostrix, and RXRA genes.ConclusionsWe have shown for the first time that mechanical loading of bone and early life vitamin D deficiency leads to changes in the epigenome of this tissue in key genes in the vitamin D and osteoblast differentiation pathway.

Expression of Beta-Catenin, Cadherins and P-Runx2 in Fibro-Osseous Lesions of the Jaw: Tissue Microarray Study.

Fibrous dysplasia (FD) and hyperparathyroidism-jaw tumor syndrome (HPT-JT) are well-characterized benign bone fibro-osseous lesions. The intracellular mechanism leading to excessive deposition of fibrous tissue and alteration of differentiation processes leading to osteomalacia have not yet been fully clarified. Tissue Microarray (TMA)-based immunohistochemical expression of β-catenin, CK-AE1/AE3, Ki-67, cadherins and P-Runx2 were analyzed in archival samples from nine patients affected by FD and HPT-JT and in seven controls, with the aim of elucidating the contribution of these molecules (β-catenin, cadherins and P-Runx2) in the osteoblast differentiation pathway. β-catenin was strongly upregulated in FD, showing a hyper-cellulated pattern, while it was faintly expressed in bone tumors associated with HPT-JT. Furthermore, the loss of expression of OB-cadherin in osteoblast lineage in FD was accompanied by N-cadherin and P-cadherin upregulation (p < 0.05), while E-cadherin showed a minor role in these pathological processes. P-Runx2 showed over-expression in six out of eight cases of FD and stained moderately positive in the rimming lining osteoblasts in HPT-JT syndrome. β-catenin plays a central role in fibrous tissue proliferation and accompanies the lack of differentiation of osteoblast precursors in mature osteoblasts in FD. The study showed that the combined evaluation of the histological characteristics and the histochemical and immunohistochemical profile of key molecules involved in osteoblast differentiation are useful in the diagnosis, classification and therapeutic management of fibrous-osseous lesions.

Mechanisms of electroacupuncture underlying treatment of osteoporosis based on HDAC2-mediated osteoblast differentiation pathway

To observe the effect of electroacupuncture (EA) on expression of histone deacetylase 2 (HDAC2), histone H3, bone formation related genes and proteins in osteoporosis rats, so as to reveal its mechanisms underlying improvement of osteoporosis. Female SD rats were randomly divided into 4 groups: sham operation, model, EA and medication (n＝ 10 rats in each group). The osteoporosis model was established by castration. EA (2 Hz, 1 mA) was applied to bilateral "Shenshu" (BL23) and "Pishu" (BL20) for 10 min, once every other day for 8 weeks. Rats of the medication group received subcutaneous injection of 17 β-estradiol (100 µg/kg, 20 µg/mL). The bone quality and quantity including the cortical bone mineral density (CBMD), trabecular bone mineral density (TBMD), ratio of bone volume /total volume (BV /TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb. Sp), trabecular bone pattern factor (Tb.Pf), and structure model index (SMI) of the right thigh-bone were detected by using a micro-computed tomography. Serum alkaline phosphatase (ALP) and estrogen 2 (E2) contents were assayed by using colorimetry and ELISA, expression levels of HDAC2, histone H3 and Runx2 in the thigh-bone were detected using Western blot, and that of Runx2 mRNA was detected using quantitative real-time PCR, separately. The co-expression of Ac-histone H3/Runx2 and Runx2/ALP was observed by using immunofluorescence histochemical staining. After modeling, the levels of TBMD, BV/TV, Tb.Th, and Tb.N, serum E2 and ALP, and expression of Runx2 protein and mRNA, Ac-histone and ALP proteins were significantly lower (P<0.01), and those of Tb.Sp, Tb.Pf and SMI, HDAC2 and histone H3 proteins were significantly higher (P<0.01) in the model group than those in the sham operation group. After the interventions, the decrease of TBMD, BV/TV, Tb.N，Runx2 protein and mRNA，ALP in both EA and medication groups, serum E2 in the medication group, and Ac-histone H3 in the EA group, and the increase of Tb.Sp in the medication group, Tb.Pf, SMI, and HDAC2 in both EA and medication groups, and histone H3 in the EA group were reversed (P<0.01, P<0.05). No significant changes were found in the levels of CBMD after modeling relevant to the sham operation group, and after EA and medication interventions (P>0.05). The effects of EA were significantly superior to 17 β-estradiol in down-regulating the expression of HDAC2 and histone H3 proteins and in up-regulating expression of Ac-histone H3 protein (P<0.01，P<0.05)．. EA treatment can increase bone density, increase bone mass and trabecular bone, and promote trabecular bone rod-like changes in plate shape in osteoporosis rats, which is related to its effect in up-regulating the expression of Ac-histone H3 protein, and down-regulating the expression of bone formation-related proteins.

Identification of PTPRR and JAG1 as key genes in castration-resistant prostate cancer by integrated bioinformatics methods.

To identify novel genes in castration-resistant prostate cancer (CRPC), we downloaded three microarray datasets containing CRPC and primary prostate cancer in Gene Expression Omnibus (GEO). R packages affy and limma were performed to identify differentially expressed genes (DEGs) between primary prostate cancer and CRPC. After that, we performed functional enrichment analysis including gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway. In addition, protein-protein interaction (PPI) analysis was used to search for hub genes. Finally, to validate the significance of these genes, we performed survival analysis. As a result, we identified 53 upregulated genes and 58 downregulated genes that changed in at least two datasets. Functional enrichment analysis showed significant changes in the positive regulation of osteoblast differentiation pathway and aldosterone-regulated sodium reabsorption pathway. PPI network identified hub genes like cortactin-binding protein 2 (CTTNBP2), Rho family guanosine triphosphatase (GTPase) 3 (RND3), protein tyrosine phosphatase receptor-type R (PTPRR), Jagged1 (JAG1), and lumican (LUM). Based on PPI network analysis and functional enrichment analysis, we identified two genes (PTPRR and JAG1) as key genes. Further survival analysis indicated a relationship between high expression of the two genes and poor prognosis of prostate cancer. In conclusion, PTPRR and JAG1 are key genes in the CRPC, which may serve as promising biomarkers of diagnosis and prognosis of CRPC.

Perspectives on miRNAs as Epigenetic Markers in Osteoporosis and Bone Fracture Risk: A Step Forward in Personalized Diagnosis.

Aging is associated with an increased incidence of age-related bone diseases. Current diagnostics (e.g., conventional radiology, biochemical markers), because limited in specificity and sensitivity, can distinguish between healthy or osteoporotic subjects but they are unable to discriminate among different underlying causes that lead to the same bone pathological condition (e.g., bone fracture risk). Among recent, more sensitive biomarkers, miRNAs — the non-coding RNAs involved in the epigenetic regulation of gene expression, have emerged as fundamental post-transcriptional modulators of bone development and homeostasis. Each identified miRNA carries out a specific role in osteoblast and osteoclast differentiation and functional pathways (osteomiRs). miRNAs bound to proteins or encapsulated in exosomes and/or microvesicles are released into the bloodstream and biological fluids where they can be detected and measured by highly sensitive and specific methods (e.g., quantitative PCR, next-generation sequencing). As such, miRNAs provide a prompt and easily accessible tool to determine the subject-specific epigenetic environment of a specific condition. Their use as biomarkers opens new frontiers in personalized medicine. While miRNAs circulating levels are lower than those found in the tissue/cell source, their quantification in biological fluids may be strategic in the diagnosis of diseases that affect tissues, such as bone, in which biopsy may be especially challenging. For a biomarker to be valuable in clinical practice and support medical decisions, it must be (easily) measurable, validated by independent studies, and strongly and significantly associated with a disease outcome. Currently, miRNAs analysis does not completely satisfy these criteria, however. Starting from in vitro and in vivo observations describing their biological role in bone cell development and metabolism, this review describes the potential use of bone-associated circulating miRNAs as biomarkers for determining predisposition, onset, and development of osteoporosis and bone fracture risk. Moreover, the review focuses on their clinical relevance and discusses the pre-analytical, analytical, and post-analytical issues in their measurement, which still limits their routine application. Taken together, research and clinical findings may be helpful for creating miRNA-based diagnostic tools in the diagnosis and treatment of bone diseases.

Dchs1-Fat4 regulation of osteogenic differentiation in mouse.

In human, mutations of the protocadherins FAT4 and DCHS1 result in Van Maldergem syndrome, which is characterised, in part, by craniofacial abnormalities. Here, we analyse the role of Dchs1-Fat4 signalling during osteoblast differentiation in mouse. We show that Fat4 and Dchs1 mutants mimic the craniofacial phenotype of the human syndrome and that Dchs1-Fat4 signalling is essential for osteoblast differentiation. In Dchs1/Fat4 mutants, proliferation of osteoprogenitors is increased and osteoblast differentiation is delayed. We show that loss of Dchs1-Fat4 signalling is linked to increased Yap-Tead activity and that Yap is expressed and required for proliferation in osteoprogenitors. In contrast, Taz is expressed in more-committed Runx2-expressing osteoblasts, Taz does not regulate osteoblast proliferation and Taz-Tead activity is unaffected in Dchs1/Fat4 mutants. Finally, we show that Yap and Taz differentially regulate the transcriptional activity of Runx2, and that the activity of Yap-Runx2 and Taz-Runx2 complexes is altered in Dchs1/Fat4 mutant osteoblasts. In conclusion, these data identify Dchs1-Fat4 as a signalling pathway in osteoblast differentiation, reveal its crucial role within the early Runx2 progenitors, and identify distinct requirements for Yap and Taz during osteoblast differentiation.

Deregulated miRNAs in osteoporosis: effects in bone metastasis.

Starting from their role exerted on osteoblast and osteoclast differentiation and activity pathways, microRNAs (miRNAs) have been recently identified as regulators of different processes in bone homeostasis. For this purpose, in a recent review, we highlighted, as deregulated miRNAs could be involved in different bone diseases such as osteoporosis. In addition, recent studies supported the concept that osteoporosis-induced bone alterations might offer a receptive site for cancer cells to form bone metastases, However, to date, no data on specific-shared miRNAs between osteoporosis and bone metastases have been considered and described to clarify the evidence of this link. The main goal of this review is to underline as deregulated miRNAs in osteoporosis may have specific roles in the development of bone metastases. The review showed that several circulating osteoporotic miRNAs could facilitate tumor progression and bone-metastasis formation in several tumor types, i.e., breast cancer, prostate cancer, non-small-cell lung cancer, esophageal squamous cell carcinoma, and multiple myeloma. In detail, serum up-regulation of pro-osteoporotic miRNAs, as well as serum down-regulation of anti-osteoporotic miRNAs are common features of all these tumors and are able to promote bone metastasis. These results are of key importance and could help researcher and clinicians to establish new therapeutic strategies connected with deregulation of circulating miRNAs and able to interfere with pathogenic processes of osteoporosis, tumor progressions, and bone-metastasis formation.

Methylation and PTEN activation in dental pulp mesenchymal stem cells promotes osteogenesis and reduces oncogenesis

Lineage commitment and tumorigenesis, traits distinguishing stem cells, have not been well characterized and compared in mesenchymal stem cells derived from human dental pulp (DP-MSCs) and bone marrow (BM-MSCs). Here, we report DP-MSCs exhibit increased osteogenic potential, possess decreased adipogenic potential, form dentin pulp-like complexes, and are resistant to oncogenic transformation when compared to BM-MSCs. Genome-wide RNA-seq and differential expression analysis reveal differences in adipocyte and osteoblast differentiation pathways, bone marrow neoplasm pathway, and PTEN/PI3K/AKT pathway. Higher PTEN expression in DP-MSCs than in BM-MSCs is responsible for the lineage commitment and tumorigenesis differences in both cells. Additionally, the PTEN promoter in BM-MSCs exhibits higher DNA methylation levels and repressive mark H3K9Me2 enrichment when compared to DP-MSCs, which is mediated by increased DNMT3B and G9a expression, respectively. The study demonstrates how several epigenetic factors broadly affect lineage commitment and tumorigenesis, which should be considered when developing therapeutic uses of stem cells.

Cajanolactone A from Cajanus cajan Promoted Osteoblast Differentiation in Human Bone Marrow Mesenchymal Stem Cells via Stimulating Wnt/LRP5/β-Catenin Signaling.

Cajanolactone A (CLA) is a stilbenoid discovered by us from Cajanus cajan (L.) Millsp. In our study, CLA was found to promote osteoblast differentiation in human bone marrow mesenchymal stem cells (hBMSCs), as judged by increased cellular alkaline phosphatase activity and extracellular calcium deposits, and elevated protein expression of Runx2, collagen-1, bone morphogenetic protein-2, and osteopontin. Mechanistic studies revealed that hBMSCs undergoing osteoblast differentiation expressed upregulated mRNA levels of Wnt3a, Wnt10b, LRP5/6, Frizzled 4, β-catenin, Runx2, and Osterix from the early stage of differentiation, indicating the role of activated Wnt/β-catenin signaling pathway in osteoblast differentiation. Addition of CLA to the differentiation medium further increased the mRNA level of Wnt3a, Wnt10b, Frizzled 4, LRP5, and β-catenin, inferring that CLA worked by stimulating Wnt/LRP5/β-catenin signaling. Wnt inhibitor dickkopf-1 antagonized CLA-promoted osteoblastogenesis, indicating that CLA did not target the downstream of canonical Wnt signaling pathway. Treatment with CLA caused no changes in mRNA expression level, as well as protein secretion of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-B ligand (RANKL), indicating that CLA did not affect the OPG/RANKL axis. Our results showed that CLA, which promoted osteoblast differentiation in hBMSCs, through activating Wnt/LRP5/β-catenin signaling transduction, is a promising anti-osteoporotic drug candidate.

Crystal structure of the PDZ domain of mouse Dishevelled 1 and its interaction with CXXC5

Dishevelled (Dvl) plays a crucial role in Wnt signaling by interacting with membrane-bound receptors and downstream molecules through its PDZ domain. CXXC5 is one of the key molecules that interacts with Dvl and negatively regulates the Wnt/β-catenin pathway in osteoblast differentiation. Recently, the Dvl-CXXC5 interaction has been identified as an excellent target for osteoporosis treatment. Therefore, it is desirable to have detailed structural information for the Dvl-CXXC5 interaction. Although solution structures of the Dvl1 PDZ domain have been reported, a high-resolution crystal structure would provide detailed sidechain information that is essential for drug development. Here, we determined the first crystal structure of the Dvl-1 PDZ domain at a resolution of 1.76 Å, and compared it with its previously reported solution structure. The Dvl1 PDZ domain crystal belonged to the space group H32 with unit-cell parameters a = b = 72.837, c = 120.616, α = β = 90.00, γ = 120.00. The crystal structure of Dvl1 PDZ shared its topology with the previously reported structure determined by nuclear magnetic resonance (NMR); however, the crystal structure was quite different from the solution structure in both the secondary structural region and the ligand-binding pocket. Molecular modeling based on NMR and X-ray crystallographic data yielded detailed information about the Dvl1/CXXC5 interaction, which will be useful for designing inhibitors.

The crosstalk between canonical and noncanonical Wnt signaling pathway in osteoblast differentiation of periodontal ligament stem cells in inflammatory microenvironments

Objective: To investigate the crosstalk between canonical Wnt/β-catenin and noncanonical Wnt/Ca2+ pathway in osteoblast differentiation process of periodontal ligament stem cell (PDLSC) in inflammatory microenvironments. Methods: PDLSCs were obtained from human healthy individuals(H-PDLSC) and patients with periodontitis(P-PDLSC). The H/P-PDLSCs were transfected with β-catenin siRNA. Cell morphology was observed under fluorescent microscope and transfection efficiency was easured by Western blotting after transfection of PDLSC. The mRNA expressions of Runt-related transcription factor 2(Runx2), β-catenin and nemo like kinase(NLK) were detected by real time PCR, the protein expressions of calcium/calmodulin-dependent protein kinase Ⅱ (CaMK Ⅱ) and NLK were examined by Western blotting and the CaMK Ⅱ was observed by immunofluorescence staining, respectively. Results: The β-catenin expressions in H/P-PDLSCs were inhibited specifically and efficiently by treatment of β-catenin-siRNA for 24 h. After a 3-day-osteogenic process, results of real-time quantitative PCR showed that the Runx2 mRNA expression in P-PDLSC siRNA β-catenin transfected group(4.553 ± 0.659) was significantly higher than that in P-PDLSC empty plasmid control group(1.918 ± 0.315) (P=0.000). A similar trend was observed in the NLK mRNA expression tests(7.341 ± 1.331 vs. 5.664 ± 0.792) (P=0.030). Accordingly, the protein expression levels of CaMK Ⅱ, NLK were higher in P-PDLSC siRNA β-catenin transfected group than that in P-PDLSC empty plasmid control group in osteogenic differentiation condition for 3 days. CaMKⅡ was more strongly induced in P-PDLSC siRNA β-catenin group than that in P-PDLSC empty plasmid control group after PDLSC cultured in osteogenic medium for 3 days. Conclusions: Both canonical Wnt/β-catenin and noncanonical Wnt/Ca2+ pathway could regulate the osteogenic differentiation potential of P-PDLSC. Suppression of β-catenin by siRNA promoted osteogenic differentiation via increasing noncanonical Wnt signaling pathway of PDLSC in inflammatory microenvironments.