Thrap3 promotes osteogenesis by inhibiting the degradation of Runx2.

The dysfunction of osteogenesis is a key character in the pathogenesis of osteoporosis, but the network of signaling mechanisms in controlling the differentiation of osteoblast remain unclear. Thrap3 has been proved participating in various biological process, especially in the differentiation of stem cells. Here, we demonstrate that Thrap3 could promote osteogenesis through the inhibition of the degradation of Runx2, which is a key molecular structure in early osteoblast differentiation. Furthermore, we found that the osteogenesis enhancing capacity of Thrap3 was caused by physically binding with Sox9, inhibiting the transcriptional activity of Sox9, and then decreasing the decomposition-promoted effect of Sox9 on Runx2. Our data shows that Thrap3 promotes osteoblast differentiation through the Thrap3-Sox9-Runx2 axis. What we found may help for further clarifying the molecular mechanism of osteogenic differentiation and give a new potential therapeutic target for osteoporosis.

Glucose Fluctuations Promote Aortic Fibrosis through the ROS/p38 MAPK/Runx2 Signaling Pathway.

AIM: Glucose fluctuations may be responsible for, or further the onset of arterial hypertension, but the exact mechanisms remain unclear. The purpose of this study was to investigate the mechanisms behind and related to aortic fibrosis and aortic stiffening induced by glucose fluctuations. METHODS: Sprague-Dawley rats were injected with streptozotocin (STZ) and randomly divided into three treatment groups: controlled STZ-induced diabetes (C-STZ); uncontrolled STZ-induced diabetes (U-STZ); and STZ-induced diabetes with glucose fluctuations (STZ-GF). After 3 weeks, rat blood pressure (BP) was tested, and aortic fibrosis was detected by using the Masson trichrome staining technique. Levels of p38 mitogen-activated protein kinase (p38 MAPK), runt-related transcription factor 2 (Runx2), collagen type 1 (collagen I), and NADPH oxidases were determined by Western blot.Rat vascular smooth muscle cells in vitro were used to explore underlying mechanisms. RESULTS: The systolic BP of diabetic rats in the C-STZ, U-STZ, and STZ-GF groups was 127.67 ± 6.53, 150.03 ± 5.24, and 171.63 ± 3.53 mm Hg, respectively (p< 0.05). The mean BP of diabetic rats in the three groups was 91.20 ± 10.07, 117.29 ± 4.28, and 140.58 ± 2.14 mm Hg, respectively (p< 0.05). The diastolic BP of diabetic rats in the three groups was 73.20 ± 12.63, 101.93 ± 5.79, and 125.37 ± 4.62 mm Hg, respectively (p< 0.05). The ratios of fibrosis areas in the aortas of the three groups were 11.85 ± 1.23, 29.00 ± 0.87, and 48.36 ± 0.55, respectively (p< 0.05). The expressions of p38 MAPK, Runx2, and collagen I were significantly increased in the STZ-GF group. In vitro, applications of inhibitors of reactive oxygen species (ROS) and p38 MAPK successfully reversed glucose fluctuations that would have possibly induced aortic fibrosis. CONCLUSIONS: Blood glucose fluctuations aggravate aortic fibrosis via affecting the ROS/p38 MAPK /Runx2 signaling pathway.

The microRNA-130a-5p/RUNX2/STK32A network modulates tumor invasive and metastatic potential in non-small cell lung cancer.

BACKGROUND: Non-small cell lung cancer (NSCLC) remains a huge health burden for human health and life worldwide. Our study here was to illuminate the relevance of microRNA-130a-5p (miR-130a-5p) on growth and epithelial mesenchymal transition (EMT) in NSCLC cells along with metastasis in vivo, and to explore the underlying mechanism. METHODS: RT-qPCR was carried out for miR-130a-5p expression determination in NSCLC cells and tissue samples. Dual-luciferase reporter gene assay, RT-qPCR and western blot were carried out to study the potential targets of miR-130a-5p. Effects of miR-130a-5p, runt-related transcription factor 2 (RUNX2) and encoding serine/threonine kinase 32A (STK32A) on NSCLC proliferation, migration, invasion as well as EMT processes were assessed by cell counting kits-8, colony formation, Transwell and western blot assays. RESULTS: miR-130a-5p was diminished in NSCLC tissues and cells versus their counterparts. miR-130a-5p exerted its repressive role in NSCLC by curtailing cell viability, migration, invasion as well as EMT, while facilitating apoptosis. miR-130a-5p directly targeted RUNX2, a transcription factor, and conversely regulated its expression. RUNX2 was found to interact with STK32A to promote its expression. Following the validation of the supporting role of STK32A in NSCLC cells and NF-κB p65 phosphorylation, RUNX2 overexpression was monitored to reverse miR-130a-5p-inhibited NSCLC tumor volume and weight through enhancing STK32A expression in vivo. CONCLUSIONS: miR-130a-5p diminished the growth and EMT of NSCLC cells by regulating the RUNX2/STK32A/NF-κB p65 axis, offering possible targets for the treatment for NSCLC.

New Function of RUNX2 in Regulating Osteoclast Differentiation via the AKT/NFATc1/CTSK Axis.

Cleidocranial dysplasia is an autosomal dominant skeletal disorder resulting from RUNX2 mutations. The influence of RUNX2 mutations on osteoclastogenesis and bone resorption have not been reported. To investigate the role of RUNX2 in osteoclast, RUNX2 expression in macrophages (RAW 264.7 cells) was detected. Stable RAW 264.7 cell lines expressing wild-type RUNX2 or mutated RUNX2 (c.514delT, p.172 fs) were established, and their functions in osteoclasts were investigated. Wild-type RUNX2 promoted osteoclast differentiation, formation of F-actin ring, and bone resorption, while mutant RUNX2 attenuated the positive differentiation effect. Wild-type RUNX2 increased the expression and activity of mTORC2. Subsequently, mTORC2 specifically promoted phosphorylation of AKT at the serine 473 residue. Activated AKT improved the nuclear translocation of NFATc1 and increased the expression of downstream genes, including CTSK. Inhibition of AKT phosphorylation abrogated the osteoclast formation of wild-type macrophages, whereas constitutively activated AKT rescued the osteoclast formation of mutant macrophages. The present study suggested that RUNX2 promotes osteoclastogenesis and bone resorption through the AKT/NFATc1/CTSK axis. Mutant RUNX2 lost the function of regulating osteoclast differentiation and bone remodeling, resulting in the defective formation of the tooth eruption pathway and impaction of permanent teeth in cleidocranial dysplasia. This study, for the first time, verifies the effect of RUNX2 on osteoclast differentiation and bone resorption and provides new insight for the explanation of cleidocranial dysplasia.

LncRNA E2F-Mediated Cell Proliferation Enhancing lncRNA Regulates Cancer Cell Behaviors and Affects Prognosis of Gastric Cancer.

BACKGROUND: A recent study reported a novel long non-coding RNA (lncRNA) E2F-mediated cell proliferation enhancing lncRNA (EPEL, human chromosome 4, intergenic region) plays an oncogenic role in lung cancer. AIMS: We aimed to investigate the role of lncRNA EPEL in gastric cancer. METHODS: Gene expression was analyzed by RT-qPCR and western blot. Survival analysis was performed by comparing survival curves. Cell proliferation, migration, and invasion were analyzed by CCK-8 and Transwell assays. RESULTS: We found that lncRNA EPEL and Runt-related transcription factor 2 (RUNX2) were both upregulated in gastric cancer. EPEL and RUNX2 were positively correlated in tumor. Patients with high expression level of lncRNA EPEL showed poor survival. LncRNA EPEL and RUNX2 overexpression promoted, while lncRNA EPEL siRNA silencing inhibited the migration, proliferation, and invasion of gastric cancers. In addition, RUNX2 overexpression completely rescued the inhibited cancer cell migration, proliferation, and invasion caused by lncRNA EPEL siRNA silencing. Consistently, EPEL overexpression resulted in upregulated RUNX2 expression, while RUNX2 overexpression did not affect lncRNA EPEL expression. CONCLUSIONS: Therefore, lncRNA EPEL may regulate cancer cell behaviors and affect prognosis of gastric cancer by interacting with RUNX2.

Runx2 function in cells of neural crest origin during intramembranous ossification.

Runt-related transcription factor 2 (Runx2), also known as core binding factor 1 (Cbfa1), is a multifunctional transcription factor and an essential master gene controlling osteoblast differentiation. We previously demonstrated the in vivo functions of Runx2 in mesoderm-derived cells. However, no studies have been conducted on Runx2 function during the differentiation of neural crest (NC)-derived cells in vivo. Wingless-type MMTV integration site family member 1 (Wnt1) is expressed in the NC, and Wnt1-Cre efficiently targets craniofacial NC-derived cells. Runx2 deficiency in cells of the Wnt1 lineage (referred henceforth as Runx2wnt1-/- within mice) resulted in defective ossification in certain regions, primarily in the anterior half of the craniofacial bones, including the frontal bone, jugal bone, squamous temporal bone, mandible, maxilla, and nasal bone. The skeletal analysis also revealed that heterozygous Runx2wnt1+/- embryos had an impaired closure of the frontal bone at the metopic suture and lacked the secondary palate in spite of otherwise normal ossification. This result suggests that ossification at the central part of the frontal bone is more dependent on Runx2 expression in comparison to other areas. These results indicate that Runx2 is indispensable not only for mesoderm-derived cells but also for NC-derived cells to differentiate during intramembranous ossification after migration to their destination from the neural plate border. Moreover, this implies that there are different levels of dependency on Runx2 expression for successful ossification between NC-derived cells that have migrated to different locations.

Postnatal Runx2 deletion leads to low bone mass and adipocyte accumulation in mice bone tissues.

Global gene deletion studies have established that Runt-related transcription factor-2 (Runx2) is essential during skeletogenesis for osteoblastic differentiation in both intramembranous and endochondral ossification processes. However, the postnatal significance of Runx2 in vivo is poorly understood because a global Runx2 deletion causes perinatal lethality. In this study, we generated tamoxifen-induced Runx2 global deficient mice by crossing Runx2flox mice with ROSA26-CreERT2 mice (Rosa26-CreERT2; Runx2flox/flox). Four-week-old mice were intraperitoneally treated with tamoxifen for five consecutive days, sacrificed, and analyzed six weeks after tamoxifen administration. Deletion of Runx2 led to low bone mass, which is associated with decreased bone formation and bone resorption as well as excessive bone marrow adiposity. Collectively, postnatal Runx2 absolutely plays an important role in maintaining the homeostasis of bone tissues not only in bone mass, but also in the bone marrow environment.

Neural EGFL-Like 1 Regulates Cartilage Maturation through Runt-Related Transcription Factor 3-Mediated Indian Hedgehog Signaling.

The pro-chondrogenic function of runt-related transcription factor 2 (Runx2) was previously considered to be dependent on direct binding with the promoter of Indian hedgehog (Ihh)-the major regulator of chondrocyte differentiation, proliferation, and maturation. The authors' previous studies identified neural EGFL like 1 (Nell-1) as a Runx2-responsive growth factor for chondrogenic differentiation and maturation. In this study, it was further revealed that the pro-chondrogenic activities of Nell-1 also rely on Ihh signaling, by showing: i) Nell-1 significantly elevated Ihh signal transduction; ii) Nell-1 deficiency markedly reduced Ihh activation in chondrocytes; and iii) Nell-1-stimulated chondrogenesis was significantly reduced by the specific hedgehog inhibitor cyclopamine. Importantly, the authors demonstrated that Nell-1-responsive Ihh signaling and chondrogenic differentiation extended to Runx2-/- models in vitro and in vivo. In Runx2-/- chondrocytes, Nell-1 stimulated the expression and signal transduction of Runx3, another transcription factor required for complete chondrogenic differentiation and maturation. Furthermore, knocking down Runx3 in Runx2-/- chondrocytes abolished Nell-1's stimulation of Ihh-associated molecule expression, which validates Runx3 as a major mediator of Nell-1-stimulated Ihh activation. For the first time, the Runx2→Nell-1→Runx3→Ihh signaling cascade during chondrogenic differentiation and maturation has been identified as an alternative, but critical, pathway for Runx2 to function as a pro-chondrogenic molecule via Nell-1.

Downregulation of MANCR inhibits cancer cell proliferation in mantle cell lymphoma possibly by interacting with RUNX2.

The mitotically associated lncRNA (MANCR) participates in breast cancer cell proliferation, while its involvement in other cancers is still unknown. In this study, we therefore studied the role of MANCR in mantle cell lymphoma (MCL). We found that serum MANCR and Runt-related transcription factor 2 (RUNX2) were upregulated in MCL patients when compared with those in healthy controls. A positive correlation between serum MANCR and RUNX2 was found in MCL patients but not in controls. Upregulation of serum MANCR distinguished MCL patients from controls. MANCR overexpression promoted RUNX2 expression in MCL cells, while RUNX2 overexpression failed to significantly change the expression levels of MANCR. MANCR overexpression promoted the proliferation of MCL cells, while MANCR silencing inhibited the proliferation of MCL cells. In addition, RUNX2 overexpression attenuated the inhibitory effects of MANCR silencing on cell proliferation. However, MANCR overexpression and silencing had no significant effects on cell migration and invasion. Further bioinformatics analysis showed that MANCR may sponge miR-218 to upregulate RUNX2. Therefore, we conclude that downregulation of MANCR may inhibit cancer cell proliferation in MCL possibly by interacting with RUNX2.

Runx2-I is an Early Regulator of Epithelial-Mesenchymal Cell Transition in the Chick Embryo.

BACKGROUND: Although normally linked to bone and cartilage development, the Runt-related transcription factor, RUNX2, was reported in the mouse heart during development of the valves. We examined RUNX2 expression and function in the developing avian heart as it related to the epithelial-mesenchymal transition (EMT) in the atrioventricular canal. EMT can be separated into an activation stage involving hypertrophy and cell separation and an invasion stage where cells invade the extracellular matrix. The localization and activity of RUNX2 was explored in relation to these steps in the heart. As RUNX2 was also reported in cancer tissues, we examined its expression in the progression of esophageal cancer in staged tissues. RESULTS: A specific isoform, RUNX2-I, is present and required for EMT by endothelia of the atrioventricular canal. Knockdown of RUNX2-I inhibits the cell-cell separation that is characteristic of initial activation of EMT. Loss of RUNX2-I altered expression of EMT markers to a greater extent during activation than during subsequent cell invasion. Transforming growth factor beta 2 (TGFß2) mediates activation during cardiac endothelial EMT. Consistent with a role in activation, RUNX2-I is regulated by TGFß2 and its activity is independent of similarly expressed Snai2 in regulation of EMT. Examination of RUNX2 expression in esophageal cancer showed its upregulation concomitant with the development of dysplasia and continued expression in adenocarcinoma. CONCLUSIONS: These data introduce the RUNX2-I isoform as a critical early transcription factor mediating EMT in the developing heart after induction by TGFß2. Its expression in tumor tissue suggests a similar role for RUNX2 in the EMT of metastasis. Developmental Dynamics 247:542-554, 2018. © 2017 Wiley Periodicals, Inc.

ATF6a, a Runx2-activable transcription factor, is a new regulator of chondrocyte hypertrophy.

Our previous research has shown that the spliced isoform of XBP1 (XBP1s) is an important downstream mediator of BMP2 and is involved in BMP2-stimulated chondrocyte differentiation. Herein, we report that ATF6 and its cleaved N-terminal cytoplasmic domain (known as ATF6a) are expressed in growth plate chondrocytes. We find that these proteins are differentially induced during BMP2-triggered chondrocyte differentiation. This differential expression probably results from the activation of the ATF6 gene by Runx2 and its repression by the Sox6 transcription factor. Runx2 and Sox6 act through their respective binding elements on the ATF6 gene. When overexpressed, ATF6 and ATF6a intensify chondrogenesis; our studies demonstrate that under the stimulation of ATF6 and ATF6a, chondrocytes tend to be hypertrophied and mineralized, a process leading to bone formation. By contrast, lowering expression of ATF6a by use of its specific siRNA suppresses chondrocyte differentiation. Moreover, ATF6a interacts with Runx2 and augments the Runx2-mediated hypertrophication of chondrocytes. Importantly, overexpression and knockdown of ATF6a during the chondrocyte hypertrophy process also led to altered expressions of IHH and PTHrP (also known as PTHLH). Taken together, these findings indicate that ATF6a favorably controls chondrogenesis and bone formation (1) by acting as a co-factor of Runx2 and enhancing Runx2-incited hypertrophic chondrocyte differentiation, and (2) by affecting IHH and PTHrP signaling.

Neural EGFL-Like 1 Is a Downstream Regulator of Runt-Related Transcription Factor 2 in Chondrogenic Differentiation and Maturation.

Recent studies indicate that neural EGFL-like 1 (Nell-1), a secretive extracellular matrix molecule, is involved in chondrogenic differentiation. Herein, we demonstrated that Nell-1 serves as a key downstream target of runt-related transcription factor 2 (Runx2), a central regulator of chondrogenesis. Unlike in osteoblast lineage cells where Nell-1 and Runx2 demonstrate mutual regulation, further studies in chondrocytes revealed that Runx2 tightly regulates the expression of Nell-1; however, Nell-1 does not alter the expression of Runx2. More important, Nell-1 administration partially restored Runx2 deficiency-induced impairment of chondrocyte differentiation and maturation in vitro, ex vivo, and in vivo. Mechanistically, although the expression of Nell-1 is highly reliant on Runx2, the prochondrogenic function of Nell-1 persisted in Runx2-/- scenarios. The biopotency of Nell-1 is independent of the nuclear import and DNA binding functions of Runx2 during chondrogenesis. Nell-1 is a key functional mediator of chondrogenesis, thus opening up new possibilities for the application of Nell-1 in cartilage regeneration.

BCL11B regulates sutural patency in the mouse craniofacial skeleton.

The transcription factor BCL11B plays essential roles during development of the immune, nervous, and cutaneous systems. Here we show that BCL11B is expressed in both osteogenic and sutural mesenchyme of the developing craniofacial complex. Bcl11b(-/-) mice exhibit increased proliferation of osteoprogenitors, premature osteoblast differentiation, and enhanced skull mineralization leading to synostoses of facial and calvarial sutures. Ectopic expression of Fgfr2c, a gene implicated in craniosynostosis in mice and humans, and that of Runx2 was detected within the affected sutures of Bcl11b(-/-) mice. These data suggest that ectopic expression of Fgfr2c in the sutural mesenchyme, without concomitant changes in the expression of FGF ligands, appears to induce the RUNX2-dependent osteogenic program and craniosynostosis in Bcl11b(-/-) mice.

[MicroRNA-150 inhibits osteosarcoma cell proliferation by targeting RUNX2 gene].

OBJECTIVE: To investigate the microRNA (miR)-150 expression level in human osteosarcoma cell lines (Saos-2, MG-63) and its function in cell proliferation, and to explore the potential molecular mechanisms. 
 Methods: MiR-150 expression levels in human osteosarcoma cell lines (Saos-2, MG-63) and normal osteoblast cell line (NHOst) were detected by relative quantitative real-time PCR (qRT-PCR). MiR-150 was overexpressed in Saos-2 and MG-63 cells by lentivirus infection. Cell proliferation rates were monitored by MTS assay. RUNX2 and ß-actin protein levels were examined by Western blot. Inhibitory effect of miR-150 on binding RUNX2 3'-UTR was detected by Dual-Luciferase assay.
 Results: MiR-150 expression level is lower in human osteosarcoma cell lines (Saos-2, MG-63) compared to the normal osteoblast cell line (NHOst) (0.23±0.02 and 0.32±0.03 vs 1.00±0.02), which showed statistical significance (P<0.01). After lentivirus infection, miR-150 level increased in Saos-2 (P<0.01) and MG-63 cells (P<0.01). Overexpression of miR-150 decreased cell proliferation and RUNX2 protein level in Saos-2 and MG-63 cells. The binding of miR-150 to RUNX2 3'-UTR decreased luciferase activity by 69% in Saos-2 cells (P<0.05) and 59% in MG-63 cells (P<0.05). Administration of exogenous RUNX2 recovered the cell proliferation in miR-150 overexpressed Saos-2 and MG-63 cell lines (P<0.01).
 Conclusion: MiR-150 inhibites proliferation in human osteosarcoma cell lines through binding to RUNX2 3'-UTR, resulting in the reducion of RUNX2 protein level.

The RUNX2 cistrome in osteoblasts: characterization, down-regulation following differentiation, and relationship to gene expression.

RUNX2 is a transcription factor that is first expressed in early osteoblast-lineage cells and represents a primary determinant of osteoblastogenesis. While numerous target genes are regulated by RUNX2, little is known of sites on the genome occupied by RUNX2 or of the gene networks that are controlled by these sites. To explore this, we conducted a genome-wide analysis of the RUNX2 cistrome in both pre-osteoblastic MC3T3-E1 cells (POB) and their mature osteoblast progeny (OB), characterized the two cistromes and assessed their relationship to changes in gene expression. We found that although RUNX2 was widely bound to the genome in POB cells, this binding profile was reduced upon differentiation to OBs. Numerous sites were lost upon differentiation, new sites were also gained; many sites remained common to both cell states. Additional features were identified as well including location relative to potential target genes, abundance with respect to single genes, the frequent presence of a consensus TGTGGT RUNX2 binding motif, co-occupancy by C/EBPß and the presence of a typical epigenetic histone enhancer signature. This signature was changed quantitatively following differentiation. While RUNX2 binding sites were associated extensively with adjacent genes, the distal nature of the majority of these sites prevented assessment of whether they represented direct targets of RUNX2 action. Changes in gene expression, however, revealed an abundance of genes that contained RUNX2 binding sites and were regulated in concert. These studies establish a basis for further analysis of the role of RUNX2 activity and its function during osteoblast lineage maturation.

Runx2-Smad signaling impacts the progression of tumor-induced bone disease.

Runx2, a master regulator of osteogenesis, is abnormally expressed in advanced prostate cancer. Here, we addressed Runx2 contribution to formation of prostate cancer-related osteolytic and osteoblastic bone lesions by mediating TGFß/BMP signaling through direct interaction with Smads. Further, we examined involvement of the Runx2-Smad complex in mediating tumor growth and distal metastasis. To identify Runx2-Smad-specific mechanisms of prostate tumor activity in bone, we generated PC3 prostate cancer cell lines expressing Runx2-WT or one of two mutant proteins (Runx2-HTY and Runx2-ΔC) that each disrupt the Runx2-Smad interaction, either directly through a point mutation or by deletion of the functional C-terminus, respectively. Intratibial tumors generated from these cells revealed that Runx2-WT-expressing cells resulted in predominantly osteolytic disease, whereas cells expressing mutant proteins exhibited tumors with mixed osteolytic/osteoblastic lesions. Extent of bone loss and woven bone formation was assessed by radiography and micro-computed tomography. Bioluminescent imaging showed the presence of labeled prostate cancer cells in the lung at the latest time point examined, with Runx2-WT group exhibiting increased incidence of tumor cells in lung. Notably, disruption of the Runx2-Smad interaction significantly reduced incidence and size of lung tumors. Altered expression of Runx2 target genes involved in invasion, growth, adhesion and metastasis supported our findings. Thus, our studies demonstrate that Runx2 in prostate cancer cells plays a significant role in intratibial prostate cancer-related tumor growth and bone loss through mechanisms mediated by the Runx2-Smad signaling pathway. This work expands upon the potential importance of Runx2 as a therapeutic target in cancer.

Ucma, a direct transcriptional target of Runx2 and Osterix, promotes osteoblast differentiation and nodule formation.

OBJECTIVE: Runt-related transcription factor 2 (Runx2) and Osterix (Osx) are the master transcription factors in bone formation. Nonetheless, genes acting downstream of both Runx2 and Osx have yet to be fully characterized. Here, we investigate the downstream targets of both Runx2 and Osx in osteoblasts. MATERIALS AND METHODS: DNA microarray analysis was conducted on calvarial RNA from wild-type, Runx2 heterozygous, Osx heterozygous, and Runx2/Osx double heterozygous embryos. Expression and transcriptional responses of the selected target gene were analyzed in MC3T3-E1 osteoblastic cells. RESULTS: The expression of unique cartilage matrix-associated protein (Ucma) was decreased in Runx2/Osx double heterozygous embryos. In contrast, Ucma expression was increased in osteoblasts overexpressing both Runx2 and Osx. Ucma expression was initiated mid-way through osteoblast differentiation and continued throughout the differentiation process. Transcriptional activity of the Ucma promoter was increased upon transfection of the cells with both Runx2 and Osx. Runx2-and Osx-mediated activation of the Ucma promoter was directly regulated by Runx2-and/or Sp1-binding sites within its promoter. During osteoblast differentiation, the formation of mineralized nodules in Ucma-overexpressing stable clones occurred earlier and was more enhanced than that in the mock-transfected control. Mineralized nodule formation was strongly augmented in the cells cultured in a medium containing secretory Ucma proteins. CONCLUSION: Ucma is a novel downstream gene regulated by both Runx2 and Osx and it stimulates osteoblast differentiation and nodule formation.

Crucial roles of canonical Runx2-dependent pathway on Wnt1-induced osteoblastic differentiation of human periodontal ligament fibroblasts.

Canonical Wnt signaling is thought to enhance osteogenic differentiation of human periodontal ligament fibroblasts (hPLFs). However, the mechanism of this enhancement has not yet been defined. We investigated the effects of Wnt1 on osteoblast differentiation of hPLFs and explored the mechanisms of the effects. Treating hPLFs with Wnt1 induced cytosolic accumulation and nuclear translocation of ß-catenin with concomitant increases in alkaline phosphatase (ALP) activity and calcium content in a time-dependent and dose-dependent manner. Wnt1-stimulated differentiation of hPLFs was accompanied by augmented phosphorylation of glycogen synthase kinase (GSK)-3ß and expression of the bone-specific factors runt-related transcription factor 2 (Runx2), osterix2 (Osx2), ALP, type I collagen, osteopontin, and osteocalcin. Pretreatment with Dickkopf-1 inhibited Wnt1-stimulated differentiation of hPLFs by suppressing GSK-3ß phosphorylation, nuclear translocation of ß-catenin, and expression of the bone-specific factors. Small interfering (si) RNA-mediated knockdown of ß-catenin, or pretreatment with FH535, markedly prevented Wnt1-stimulated differentiation of cells by blocking Runx2 and its downstream factors at the mRNA and protein levels. siRNA-mediated silencing of Runx2 also inhibited Wnt1-stimulated mineralization of cells, accompanied by a reduction in the levels of Osx2 and other early and late bone-formation regulatory factors. However, Wnt1-mediated nuclear translocation of ß-catenin and GSK-3ß phosphorylation were not inhibited by knockdown of Runx2 or FH535. Collectively, our findings suggested that Wnt1 stimulates osteogenic differentiation and mineralization of hPLFs, mainly by activating the canonical Wnt/ß-catenin pathway, in which Runx2 is a key downstream regulator.

[Vascular Calcification - Pathological Mechanism and Clinical Application - . Role of vascular smooth muscle cells in vascular calcification].

Vascular calcification is commonly seen with aging, chronic kidney disese (CKD), diabetes, and atherosclerosis, and is closely associated with cardiovascular morbidity and mortality. Vascular calcification has long been regarded as the final stage of degeneration and necrosis of arterial wall and a passive, unregulated process. However, it is now known to be an active and tightly regulated process involved with phenotypic transition of vascular smooth muscle cells (VSMC) that resembles bone mineralization. Briefly, calcium deposits of atherosclerotic plaque consist of hydroxyapatite and may appear identical to fully formed lamellar bone. By using a genetic fate mapping strategy, VSMC of the vascular media give rise to the majority of the osteochondrogenic precursor- and chondrocyte-like cells observed in the calcified arterial media of MGP (- / -) mice. Osteogenic differentiation of VSMC is characterized by the expression of bone-related molecules including bone morphogenetic protein (BMP) -2, Msx2 and osteopontin, which are produced by osteoblasts and chondrocytes. Our recent findings are that (i) Runx2 and Notch1 induce osteogenic differentiation, and (ii) advanced glycation end-product (AGE) /receptor for AGE (RAGE) and palmitic acid promote osteogenic differentiation of VSMC. To understand of the molecular mechanisms of vascular calcification is now under intensive research area.

[Vascular Calcification - Pathological Mechanism and Clinical Application - . Vascular calcification in aged mice].

Vascular calcification is a risk factor for cerebral and cardiovascular events and has a high prevalence among elderly. To finding ways of prevent or cure vascular calcification may leads to not only a healthy longevity but also medical expenditure reduction. However, the molecular mechanism underlying this pathogenic process is still obscure. To clarify the mechanism of vascular calcification, the development of animal models that exhibit extensive and robust vascular calcification is an important issue for research in vascular biology.