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.

The role of microRNAs in the osteogenic and chondrogenic differentiation of mesenchymal stem cells and bone pathologies.

Mesenchymal stem cells (MSCs) have been identified in many adult tissues. MSCs can regenerate through cell division or differentiate into adipocytes, osteoblasts and chondrocytes. As a result, MSCs have become an important source of cells in tissue engineering and regenerative medicine for bone tissue and cartilage. Several epigenetic factors are believed to play a role in MSCs differentiation. Among these, microRNA (miRNA) regulation is involved in the fine modulation of gene expression during osteogenic/chondrogenic differentiation. It has been reported that miRNAs are involved in bone homeostasis by modulating osteoblast gene expression. In addition, countless evidence has demonstrated that miRNAs dysregulation is involved in the development of osteoporosis and bone fractures. The deregulation of miRNAs expression has also been associated with several malignancies including bone cancer. In this context, bone-associated circulating miRNAs may be useful biomarkers for determining the predisposition, onset and development of osteoporosis, as well as in clinical applications to improve the diagnosis, follow-up and treatment of cancer and metastases. Overall, this review will provide an overview of how miRNAs activities participate in osteogenic/chondrogenic differentiation, while addressing the role of miRNA regulatory effects on target genes. Finally, the role of miRNAs in pathologies and therapies will be presented.

Core Binding Factors are essential for ovulation, luteinization, and female fertility in mice.

Core Binding Factors (CBFs) are a small group of heterodimeric transcription factor complexes composed of DNA binding proteins, RUNXs, and a non-DNA binding protein, CBFB. The LH surge increases the expression of Runx1 and Runx2 in ovulatory follicles, while Cbfb is constitutively expressed. To investigate the physiological significance of CBFs, we generated a conditional mutant mouse model in which granulosa cell expression of Runx2 and Cbfb was deleted by the Esr2Cre. Female Cbfbflox/flox;Esr2cre/+;Runx2flox/flox mice were infertile; follicles developed to the preovulatory follicle stage but failed to ovulate. RNA-seq analysis of mutant mouse ovaries collected at 11 h post-hCG unveiled numerous CBFs-downstream genes that are associated with inflammation, matrix remodeling, wnt signaling, and steroid metabolism. Mutant mice also failed to develop corpora lutea, as evident by the lack of luteal marker gene expression, marked reduction of vascularization, and excessive apoptotic staining in unruptured poorly luteinized follicles, consistent with dramatic reduction of progesterone by 24 h after hCG administration. The present study provides in vivo evidence that CBFs act as essential transcriptional regulators of both ovulation and luteinization by regulating the expression of key genes that are involved in inflammation, matrix remodeling, cell differentiation, vascularization, and steroid metabolisms in mice.

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.

Functions of Exogenous RUNX2 in Giant Cell Tumor of Bone In Vitro.

OBJECTIVES: This research aimed to investigate the relative level of Runt-related transcription factor 2 (RUNX2) in giant cell tumor of bone (GCTB). Through the histopathological similarities between osteoporosis and GCTB, the biological functions of exogenous RUNXS were demonstrated in GCTB cell lines. This generated awareness of the molecular mechanism of the biogenesis and metastasis of GCTB, as well as showing the pathways and processes involved in this study. This research also expected to provide hints for the clinical treatment of patients with GCTB, to release the tumor burden and reduce the recurrence rate and metastasis of patients with this condition. METHODS: The expression of RUNX2 in the tumors was verified by Western Blot, qRT-PCR and immunohistochemistry, compared with the normal tissues' adjacent tumors. Subsequently, the plasmids expressing RUNX2 were constructed, amplified and transfected into the 0404 cell line through transfection kits (0.4, 0.8, 1.6, 2.4 ng/µl). After that, the proliferation, migration, invasion, cellular viability and apoptosis of 0404 cell lines were examined by EDU assay, wound healing assay, transwell assay, annexin v staining, and CCK8 assay, respectively. RESULTS: The messenger RNA (mRNA) level of RUNX2 in tumors was over 100 folds more than the normal tissues. The protein level of tumors upregulated 8.32(±4.41) folds relatively. After the transfection of RUNX2 overexpressed plasmids into the 0404 cell line, the mRNA level of RUNX2 increased approximately 530.11(±24.87), 1117.96(±77.68), 2835.09(±45.22) and 4781.51(±79.37) folds respectively, and the protein level was upregulated about 4.12(±1.15), 16.73(±1.63), 21.53(±2.41) and 23.39(±0.85) folds respectively. The proliferation of 0404 cells was inhibited by 2.13(±1.02)% of 1.6 ng/µl group and 3.03(±1.76)% of 2.4 ng/µl group. And the migration was inhibited about 45.56(±6.13)%, 50.79(±5.27)%, 63.15(±8.62)% and 93.90(±3.65)% respectively. The invasion was decreased about 14.49(±5.4)%, 37.02(±6.52)%, 42.24(±2.59)% and 48.97(±10.61)% respectively. Meanwhile, FITC Annexin V/PI apoptosis assay demonstrated that RUNX2 plasmids could promote apoptosis rate around 4.15(±0.27)%, 5.07(±0.27)%, 7.61(±0.45)% and 11.32(±1.02)% respectively, and CCK8 proved these plasmids could weaken cellular viability in a concentration-dependent manner with the time passing. CONCLUSIONS: RUNX2 is highly expressed in giant cell tumors of bone. The RUNX2 overexpressed plasmids we constructed could be successfully transfected into 0404 cell line. Far more importantly, the exogenous RUNX2 can seriously block the biological functions of 0404 cell line in a concentration-dependent manner, including proliferation, translocation, invasion, cellular viability, and apoptosis. Meanwhile, the mechanism was hypothesized and discussed in the article.

Regulation of Runx2 by post-translational modifications in osteoblast differentiation.

Osteogenesis is the process of new bone formation where transcription factors play an important role in controlling cell proliferation and differentiation. Runt-related transcription factor 2 (Runx2), a key transcription factor, regulates the differentiation of mesenchymal stem cells into osteoblasts, which further mature into osteocytes. Runx2 acts as a modulator such that it can either stimulate or inhibit the osteoblast differentiation. A defect/alteration in the expression/activity of this gene may lead to skeletal dysplasia. Runx2 thus serves as the best therapeutic model gene for studying bone and bone-related diseases. In this review, we briefly outline the regulation of Runx2 and its activity at the post-translational levels by the virtue of phosphorylation, acetylation, and ubiquitination in controlling the bone homeostasis.

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.

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.

HLA-B27-mediated activation of TNAP phosphatase promotes pathogenic syndesmophyte formation in ankylosing spondylitis.

Ankylosing spondylitis (AS) is a type of axial inflammation. Over time, some patients develop spinal ankylosis and permanent disability; however, current treatment strategies cannot arrest syndesmophyte formation completely. Here, we used mesenchymal stem cells (MSCs) from AS patients (AS MSCs) within the enthesis involved in spinal ankylosis to delineate that the HLA-B27-mediated spliced X-box-binding protein 1 (sXBP1)/retinoic acid receptor-ß (RARB)/tissue-nonspecific alkaline phosphatase (TNAP) axis accelerated the mineralization of AS MSCs, which was independent of Runt-related transcription factor 2 (Runx2). An animal model mimicking AS pathological bony appositions was established by implantation of AS MSCs into the lumbar spine of NOD-SCID mice. We found that TNAP inhibitors, including levamisole and pamidronate, inhibited AS MSC mineralization in vitro and blocked bony appositions in vivo. Furthermore, we demonstrated that the serum bone-specific TNAP (BAP) level was a potential prognostic biomarker to predict AS patients with a high risk for radiographic progression. Our study highlights the importance of the HLA-B27-mediated activation of the sXBP1/RARB/TNAP axis in AS syndesmophyte pathogenesis and provides a new strategy for the diagnosis and prevention of radiographic progression of AS.

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.

Regulation of Runx2 by MicroRNAs in osteoblast differentiation.

Bone is one of the most dynamic organs in the body that continuously undergoes remodeling through bone formation and resorption. A cascade of molecules and pathways results in the osteoblast differentiation that is attributed to osteogenesis, or bone formation. The process of osteogenesis is achieved through participation of the Wnt pathway, FGFs, BMPs/TGF-ß, and transcription factors such as Runx2 and Osx. The activity and function of the master transcription factor, Runx2, is of utmost significance as it can induce the function of osteoblast differentiation markers. A number of microRNAs [miRNAs] have been recently identified in the regulation of Runx2 expression/activity, thus affecting the process of osteogenesis. miRNAs that target Runx2 corepressors favor osteogenesis, while miRNAs that target Runx2 coactivators inhibit osteogenesis. In this review, we focus on the regulation of Runx2 by miRNAs in osteoblast differentiation and their potential for treating bone and bone-related diseases.

Perivascular-Derived Mesenchymal Stem Cells.

Cells have been identified in postnatal tissues that, when isolated from multiple mesenchymal compartments, can be stimulated in vitro to give rise to cells that resemble mature mesenchymal phenotypes, such as odontoblasts, osteoblasts, adipocytes, and myoblasts. This has made these adult cells, collectively called mesenchymal stem cells (MSCs), strong candidates for fields such as tissue engineering and regenerative medicine. Based on evidence from in vivo genetic lineage-tracing studies, pericytes have been identified as a source of MSC precursors in vivo in multiple organs, in response to injury or during homeostasis. Questions of intense debate and interest in the field of tissue engineering and regenerative studies include the following: 1) Are all pericytes, irrespective of tissue of isolation, equal in their differentiation potential? 2) What are the mechanisms that regulate the differentiation of MSCs? To gain a better understanding of the latter, recent work has utilized ChIP-seq (chromatin immunoprecipitation followed by sequencing) to reconstruct histone landscapes. This indicated that for dental pulp pericytes, the odontoblast-specific gene Dspp was found in a transcriptionally permissive state, while in bone marrow pericytes, the osteoblast-specific gene Runx2 was primed for expression. RNA sequencing has also been utilized to further characterize the 2 pericyte populations, and results highlighted that dental pulp pericytes are already precommitted to an odontoblast fate based on enrichment analysis indicating overrepresentation of key odontogenic genes. Furthermore, ChIP-seq analysis of the polycomb repressive complex 1 component RING1B indicated that this complex is likely to be involved in inhibiting inappropriate differentiation, as it localized to a number of loci of key transcription factors that are needed for the induction of adipogenesis, chondrogenesis, or myogenesis. In this review, we highlight recent data elucidating molecular mechanisms that indicate that pericytes can be tissue-specific precommitted MSC precursors in vivo and that this precommitment is a major driving force behind MSC differentiation.

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.

[Dissecting the Hierarchy and Lineage of Mesenchymal Stem Cells Using Mouse Genetics as a Step toward Drug Discovery and Regenerative Medicine].

The mesenchymal stem cell (MSC) is a type of tissue stem cell. In clinical studies, cultured MSCs have shown important therapeutic effects on diseases via both the reduction of neurological defects and the regulation of immune responses. However, in vivo MSC localization, function, and properties are poorly understood; therefore, the molecular understanding of MSC hierarchy is less advanced compared to hematopoietic stem cell hierarchy. Runt-related transcription factor 2 (Runx2) is an essential transcriptional regulator of osteoblast differentiation from MSCs. Runx2 deficiency in Paired-related homeobox 1 (Prrx1)-derived cells (Runx2Prrx1-/- mice) results in defective intramembranous ossification. Double-positive cells for Prrx1-GFP, and stem cell antigen-1 (Sca1) (Prrx1+Sca1+ cells) in the calvaria, express Runx2 at lower levels, and are more homogeneous and primitive compared with Prrx1+Sca1- cells. Our results suggest that osteoblast differentiation in vivo may begin at the Prrx1+Sca1+ MSC stage, with sequential progression to Prrx1+Sca1- cells, followed by Osterix+Prrx1-Sca1- osteoblast precursors, which eventually form mature α1(I)-collagen+ osteoblasts. This research will enable us to better understand the in vivo molecular biology features of MSCs, leading to their therapeutic applications for tissue repair and regeneration.

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.

Liquiritigenin Inhibits Colorectal Cancer Proliferation, Invasion, and Epithelial-to-Mesenchymal Transition by Decreasing Expression of Runt-Related Transcription Factor 2.

Inhibition of tumor metastasis is one of the most important purposes in colorectal cancer (CRC) treatment. This study aimed to explore the effects of liquiritigenin, a flavonoid extracted from the roots of Glycyrrhiza uralensis Fisch, on HCT116 cell proliferation, invasion, and epithelial-to-mesenchymal transition (EMT). We found that liquiritigenin significantly inhibited HCT116 cell proliferation, invasion, and the EMT process, but had no influence on cell apoptosis. Moreover, liquiritigenin remarkably reduced the expression of runt-related transcription factor 2 (Runx2) in HCT116 cells. Overexpression of Runx2 obviously reversed the liquiritigenin-induced invasion and EMT inhibition. Furthermore, liquiritigenin inactivated the phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway in HCT116 cells. Upregulation of Runx2 reversed the liquiritigenin-induced PI3K/AKT pathway inactivation. In conclusion, our research verified that liquiritigenin exerted significant inhibitory effects on CRC invasion and EMT process by downregulating the expression of Runx2 and inactivating the PI3K/AKT signaling pathway. Liquiritigenin could be an effective therapeutic and preventative medicine for CRC treatment.

Transdifferentiation of adipocytes to osteoblasts: potential for orthopaedic treatment.

OBJECTIVES: As both adipocytes and osteoblasts originate from the same pool of mesenchymal stem cells, increasing clinical evidence has emerged of the plasticity between the two lineages. For instance, the downregulation of osteoblast differentiation and upregulation of adipogenesis are common features of conditions such as multiple myeloma, obesity and drug-induced bone loss in diabetes mellitus. However, despite in-vitro and in-vivo observations of adipocyte transdifferentiation into osteoblasts, little is known of the underlying mechanisms. KEY FINDINGS: This review summarises the current knowledge of this particular transdifferentiation process whereby the Wnt/ß-catenin signalling pathway and Runx2 overexpression have been postulated to play a critical role. SUMMARY: Furthermore, due to the possibility of a novel therapy in the treatment of bone conditions, a number of agents with the potential to induce adipo-to-osteoblast transdifferentiation have been investigated such as all-trans retinoic acid, bone morphogenetic protein-9 and vascular endothelial growth factor.

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.

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.