p53 transactivity during in vitro osteoblast differentiation in a rat osteosarcoma cell line

Schwartz, Karin A.; Lanciloti, Natalie; Moore, Michael K.; Campione, Allan L.; Chandar, Nalini

doi:10.1002/(sici)1098-2744(199906)25:2<132::aid-mc8>3.0.co;2-2

Cited by 19 publications

(21 citation statements)

References 21 publications

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“…In previous studies carried out with a murine osteosarcoma cell line showing characteristics of mature osteoblasts, we found that loss of p53 affects the ability of the cells to secrete osteocalcin, and that this property is regained after stable transfection of the cells with wild type p53 [7]. In other studies with osteoblast cell lines capable of displaying features of bone differentiation, we also observed p53 to have a distinct transcription-activating role, unrelated to growth arrest [33]. The osteocalcin promoter of p53 positive osteoblasts responded to exogenous wild type p53, and in p53 osteoblasts from knockout mice exogenous p53 had a positive effect only on cells containing at least one copy of wild type p53 [8].…”

Section: Introductionsupporting

confidence: 53%

“…We have shown decreased expression of p53 to result in an inability of osteoblasts to express osteocalcin and mineralize in vitro [7]. P53 is a transcription factor and its transcription activating activity is high during differentiation [33]. Bone matrix proteins such as osteopontin [27] and osteocalcin (5,7 and unpublished observations) have been shown to have a p53 response element within their genes and also to be regulated by p53.…”

Section: Discussionmentioning

confidence: 76%

“…These results contrast with our observations of osteocalcin gene expression. Osteocalcin gene expression requires wild type p53 function and was not expressed when p53 was mutated [7,8,33]. BMP-2 expression did not require wild type p53 function, since both cell types (p53 mutant and wild type) express BMP-2, but its upregulation during differentiation was only detected in cells expressing wild type p53.…”

Section: Transient Transfection Of Wild Type P53 Is Not Sufficient Tomentioning

confidence: 93%

“…This cell line carries an endogenous wild type p53 and can be induced to differentiate in culture using a differentiation-promoting medium [33]. MC3T3-El, a mouse calvaria-derived cells were obtained from ATCC.…”

Section: Cell Linesmentioning

confidence: 99%

“…We initially chose to study ROS 17/2.8 cells, which contain an endogenous wild type p53 and efficiently mineralizes in culture after exposure to a differentiation promoting media [33]. These cells express alkaline phosphatase, alpha 1 collagen and osteocalcin during differentiation [7].…”

Section: Several Bmps Show Modulation During Differentiation In Ros 1mentioning

confidence: 99%

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Relationship of bone morphogenetic protein expression during osteoblast differentiation to wild type p53

et al. 2005

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We have previously shown p53 to have a specific role in osteoblast differentiation by its ability to regulate expression of certain bone specific proteins. In this study, we show mineralized matrix formation in vivo to be directly related to the presence of wild type p53 in osteoblastic osteosarcoma cells. In order to further understand the importance of p53 in differentiation, we investigated the relationship between p53 and Bone Morphogenetic Proteins (BMPs) (BMP 1, 2, 3A, 3B (GDF-lo), 4, 5, 6, 7, 8A and 8B) during osteoblast differentiation. The expression of several BMPs were tested using RNase Protection Assay in differentiating ROS17/ 2.8 osteoblastic osteosarcoma cells. The expression of BMPs 1, 2, 3a, 3b and 7 showed time dependent modulation during ih vitro differentiation. In order to determine if p53 has a role in this process, we used a murine osteosarcoma cell line stably expressing a temperature sensitive p53. Cells were exposed to ascorbic acid and glycerophosphates to hasten in vitro osteoblast differentiation and maintained either at 32 or 37 "C for expression of the wild type or mutant p53 phenotype. The expression of BMP-2, BMP-4 and BMP-7 were modulated in a p53 dependent fashion. We were able to confirm the p53 dependency of BMP-2 independently by RT-PCR. While BMP-2 expression was evident in the presence of both wild type and mutant p53, regulated expression was seen only in cells expressing wild type p53. Transient over expression of wild type p53 did not result in the same BMP-2 response as stable expression showing that the presence of p53 may be important for an orderly development of osteoblast differentiation rather than a direct effect on gene expression. The functional relationship between p53 and these bone specific markers is discussed.

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Section: Introductionsupporting

confidence: 53%

Section: Discussionmentioning

confidence: 76%

Section: Transient Transfection Of Wild Type P53 Is Not Sufficient Tomentioning

confidence: 93%

Section: Cell Linesmentioning

confidence: 99%

Section: Several Bmps Show Modulation During Differentiation In Ros 1mentioning

confidence: 99%

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Relationship of bone morphogenetic protein expression during osteoblast differentiation to wild type p53

et al. 2005

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Induction of p53 Expression and Function by Estrogen in Osteoblasts

Bovenkerk

Lanciloti

Chandar

2003

Calcified Tissue International

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While estrogen's role in maintaining bone health relates to its action on osteoclasts, not much is presently known about the role of estrogen with respect to osteoblasts. Our laboratory is involved in studying the function of the p53 tumor suppressor gene in osteoblast differentiation. This study was therefore designed to understand the role of estrogen in osteoblast growth and differentiation and its effect on p53 function. ROS 17/2.8 cells, stably transfected with a construct containing multiple copies of a p53 response element fused to a chloramphenicol acetyl transferase (CAT) gene, were used to monitor wild-type p53 activity. Maximal p53 activity was observed when E2 was given at concentrations between 10(-12) and 10(-15) M. This increase in p53 activity was due to a change in transcription and peaked at about 16 hours after treatment. An increase in p53 activity was followed by an increase in expression of p53-regulated genes p21 and mdm2. This increase in p53 activity was partially inhibited by inclusion of estrogen antagonist ICI 182,780. Bone- specific markers osteocalcin and alkaline phophatase increased after treatment with E2, as did changes in estrogen receptors alpha and beta. Upregulation of osteocalcin was reduced when cycloheximide was added to E2, suggesting the presence of intermediates in the enhancement of osteocalcin gene transcription. These findings suggest that E2 can directly mediate an increase in p53 expression and function. The relevance of this to osteoblast differentiation is discussed.

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Osteocalcin Gene Expression Is Regulated by Wild-Type p53

et al. 2011

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The tumor-suppressor p53 is a transcription factor that regulates a number of genes in the process of cell-cycle inhibition, apoptosis, and DNA damage. Recent studies have revealed a crucial role for p53 in bone remodeling. In our previous studies we have shown that p53 is an important regulator of osteoblast differentiation. In this study we investigated the role of p53 in the regulation of human osteocalcin gene expression. We observed that osteocalcin promoter activity could be upregulated by both exogenous and endogenous p53 and downregulated by p53-specific small interfering RNA. DNA affinity immunoblotting assay showed that p53 can bind to the human osteocalcin promoter in vitro. We further identified a p53 response element within the osteocalcin promoter region using a chromatin immunoprecipitation assay. Furthermore, we observed an additive effect of p53 and VDR on the regulation of osteocalcin promoter activity. Our findings suggest that p53 may directly target the human osteocalcin gene and positively affect osteocalcin gene expression.

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p53 transactivity during in vitro osteoblast differentiation in a rat osteosarcoma cell line

Cited by 19 publications

References 21 publications

Relationship of bone morphogenetic protein expression during osteoblast differentiation to wild type p53

Relationship of bone morphogenetic protein expression during osteoblast differentiation to wild type p53

Induction of p53 Expression and Function by Estrogen in Osteoblasts

Osteocalcin Gene Expression Is Regulated by Wild-Type p53

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