Differentiation of Osteoblasts from Murine Embryonic Stem Cells by Overexpression of the Transcriptional Factor Osterix

Tai, Guihua; Polak, Julia M.; Bishop, Anne E.; Christodoulou, Ioannis; Buttery, Lee D.K.

doi:10.1089/1076327042500300

Cited by 18 publications

(24 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Cbfa1 is necessary for an early step in the osteoblasts/chondrocyte differentiation pathway, whereas osterix (e.g, a zinc finger-containing protein) is required for the differentiation of pre-osteoblasts into fully functioning osteoblasts. Osterix appears to act downstream of Cbfa1 during osteogenic differentiation (Tai et al, 2004). As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Human circulating fibrocytes have the capacity to differentiate osteoblasts and chondrocytes

Choi

Burdick

Strieter

2010

The International Journal of Biochemistry & Cell Biology

View full text Add to dashboard Cite

Fibrocytes are bone marrow-derived cells. Fibrocytes can differentiate into adipocyte-and myofibroblast-like cells. Since fibrocytes can behave like mesenchymal progenitor cells, we hypothesized that fibrocytes have the potential to differentiate into other mesenchymal lineage cells, such as osteoblasts and chondrocytes. In this study, we found that fibrocytes differentiated into osteoblast-like cells when cultured in osteogenic media in a manner similar to osteoblast precursor cells. Under these conditions, fibrocytes and osteoblast precursor cells displayed increased calcium deposition, and increased expression of specific osteogenic genes. In addition, dephosphorylation of cAMP-responsive element binding protein was associated with the increased ratio of Receptor activator of the NF-κB Ligand/osteoprotegerin gene expression and enhanced gene expression of osterix in these cells under these conditions. Both events are important in promoting osteogenesis. In contrast, fibrocytes and mesenchymal stem cells cultured in chondrogenic media in the presence of transforming growth factor-β3 were found to differentiate to chondrocyte-like cells. Fibrocytes and mesenchymal stem cells under these conditions were found to express increased levels of aggrecan and type II collagen genes. Transcription factor genes associated with chondrogenesis were also found to be induced in fibrocytes and mesenchymal stem cells under these conditions. In contrast, β-catenin protein and the core binding factor alpha1 subunit protein transcription factor were decreased in expression under these conditions. These data indicate that human fibrocytes have the capability to differentiate into osteoblast-and chondrocyte-like cells. These findings suggest that such cells could be used in cell-based tissue-regenerative therapy.

show abstract

Section: Resultsmentioning

confidence: 99%

Human circulating fibrocytes have the capacity to differentiate osteoblasts and chondrocytes

Choi

Burdick

Strieter

2010

The International Journal of Biochemistry & Cell Biology

View full text Add to dashboard Cite

show abstract

“…Here the arrest in development occurs slightly later but also results in a cartilaginous skeleton (3). In addition, Osx induces OB differentiation of dispersed embryonic cells (4). RUNX2 is expressed in Osx knock-outs, suggesting that Osx functions downstream of RUNX2 in the differentiation pathway.…”

mentioning

confidence: 99%

Transcriptional Regulation of the Osterix (Osx, Sp7) Promoter by Tumor Necrosis Factor Identifies Disparate Effects of Mitogen-activated Protein Kinase and NFκB Pathways

Gilbert

et al. 2006

Journal of Biological Chemistry

126

118

View full text Add to dashboard Cite

Osteoblast (OB) differentiation is suppressed by tumor necrosis factor-␣ (TNF-␣), an inflammatory stimulus that is elevated in arthritis and menopause. Because OB differentiation requires the expression of the transcription factor osterix (Osx), we investigated TNF effects on Osx. TNF inhibited Osx mRNA in pre-osteoblastic cells without affecting Osx mRNA half-life. Inhibition was independent of new protein synthesis. Analysis of the Osx promoter revealed two transcription start sites that direct the expression of an abundant mRNA (Osx1) and an alternatively spliced mRNA (Osx2). Promoter fragments driving the expression of luciferase were constructed to identify TNF regulatory sequences. Two independent promoters were identified upstream of each transcription start site. TNF potently inhibited transcription of both promoters. Deletion and mutational analysis identified a TNF-responsive region proximal to the Osx2 start site that retained responsiveness when inserted upstream of a heterologous promoter. The TNF response region was a major binding site for nuclear proteins, although TNF did not change binding at the site. The roles of MAPK and NFB were investigated as signal mediators of TNF. Inhibitors of MEK1 and ERK1, but not of JNK or p38 kinase, abrogated TNF inhibition of Osx mRNA and promoter activity. TNF action was not prevented by blockade of NFB nuclear entry. The forced expression of high levels of NFB uncovered a proximal promoter enhancer; however, this site was not activated by TNF. The inhibitory effect of TNF on Osx expression may decrease OB differentiation in arthritis and osteoporosis. Osteoblasts (OBs)2 are derived from pluripotent precursor cells of mesenchymal origin that are capable of differentiation to chondrocytes, myocytes, adipocytes, or fibroblasts (1). Bone formation in the embryo and remodeling in the adult require that a sufficient number of precursor cells differentiate to functional OBs. New OBs are continuously required for the synthesis of bone matrix and replacement of cells becoming osteocytes or undergoing apoptosis. A coordinated expression of transcription factors determines the commitment of precursor cells toward the OB phenotype under the control of autocrine, paracrine, and hormonal stimuli. Two of these transcription factors, RUNX2 (Cbfa1/AML3/Pebp2␣A) and Osx, are required for differentiation to the OB lineage. In mice, RUNX2 gene knock-out causes a lethal mutation with a cartilaginous skeleton. RUNX2 is presumed to function as an organizer on promoters of skeletal-specific genes (2). A phenotype similar to the RUNX2 knock-out is observed with knock-out of Osx. Here the arrest in development occurs slightly later but also results in a cartilaginous skeleton (3). In addition, Osx induces OB differentiation of dispersed embryonic cells (4). RUNX2 is expressed in Osx knock-outs, suggesting that Osx functions downstream of RUNX2 in the differentiation pathway.Differentiation of precursor cells to OBs in adult bone is impaired by inflammatory stimuli. In rheumatoid arthri...

show abstract

“…The suppression of OB differentiation by MSCs is evidenced by the reduction of ALP activity and gene expression, an early marker of the OB phenotype, as well as by the reduction of BSP gene and protein expressions, OC gene expression, and mineralized matrix formation, which is the final stage of osteogenesis. Suppression of OB differentiation was likely due to the inhibition of the transcription factors RUNX2 and OSX, both of which are essential for the acquisition of an OB phenotype and subsequent bone formation [Komori et al, ; Ducy et al, ; Nakashima et al, ; Tai et al, ]. Several mechanisms may be involved in this inhibitory effect including some factors secreted by MSCs such as tumor necrosis factor‐α, which negatively affect OB phenotype expression [Li et al, ,].…”

Section: Discussionmentioning

confidence: 99%

Mesenchymal Stem Cells Repress Osteoblast Differentiation Under Osteogenic‐Inducing Conditions

Santos

Abuna

Castro‐Raucci

et al. 2015

J of Cellular Biochemistry

View full text Add to dashboard Cite

This study was designed to investigate the influence of mesenchymal stem cells (MSCs) on osteoblast (OB) differentiation. Rat bone marrow MSCs were cultured either in growth medium that maintained a MSC phenotype or in osteogenic medium that induced differentiation into OBs. Then, cells were grown in two different culture conditions: indirect co-culture of MSCs and OBs and OBs cultured in MSC-conditioned medium. As a control culture condition, OBs were grown in osteogenic medium without the influence of MSCs. We evaluated cell proliferation, the gene expression of key bone markers, alkaline phosphatase (ALP) activity, bone sialoprotein (BSP) expression, and extracellular matrix mineralization. The results showed that, regardless of whether OBs were indirectly co-cultured with MSCs or cultured in MSC-conditioned medium, MSCs repressed OB differentiation, as evidenced by the downregulation of all evaluated bone marker genes, decreased ALP activity, inhibition of BSP protein expression, and reduced extracellular matrix mineralization. Taken together, these results indicate that despite the key role of both MSCs and OBs in the osteogenic process, the repressive effect of MSCs on OB differentiation in an osteogenic environment may represent a barrier to the strategy of using them together in cell-based therapies to induce bone repair.

show abstract

Differentiation of Osteoblasts from Murine Embryonic Stem Cells by Overexpression of the Transcriptional Factor Osterix

Cited by 18 publications

References 0 publications

Human circulating fibrocytes have the capacity to differentiate osteoblasts and chondrocytes

Human circulating fibrocytes have the capacity to differentiate osteoblasts and chondrocytes

Transcriptional Regulation of the Osterix (Osx, Sp7) Promoter by Tumor Necrosis Factor Identifies Disparate Effects of Mitogen-activated Protein Kinase and NFκB Pathways

Mesenchymal Stem Cells Repress Osteoblast Differentiation Under Osteogenic‐Inducing Conditions

Contact Info

Product

Resources

About