Cbfa1 does not regulate RANKL gene activity in stromal/osteoblastic cells

O’Brien, Charles A.; Kern, Brigitt; Gubrij, Igor; Karsenty, Gérard; Manolagas, Stavros C.

doi:10.1016/s8756-3282(01)00692-5

Cited by 53 publications

(71 citation statements)

References 32 publications

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“…The lack of c-fos involvement is not unexpected, because new protein synthesis was not required for PTH stimulation of RANKL and previous work has shown that PTH stimulates c-fos indirectly via CREB (27). In addition, the lack of Runx2 involvement is consistent with our previous study indicating that this factor is not required for basal, OSM-, or 1,25(OH) 2 D 3 -stimulated RANKL expression (35). Expression of A-CREB did not completely block PTH stimulation of RANKL.…”

Section: Discussionsupporting

confidence: 90%

Parathyroid Hormone Stimulates Receptor Activator of NFκB Ligand and Inhibits Osteoprotegerin Expression via Protein Kinase A Activation of cAMP-response Element-binding Protein

Fu¹,

Jilka²,

Manolagas³

et al. 2002

Journal of Biological Chemistry

207

191

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Parathyroid hormone (PTH) stimulates osteoclast formation by binding to its receptor on stromal/osteoblastic cells and stimulating the production of receptor activator of NFB ligand (RANKL) and inhibiting the expression of osteoprotegerin (OPG). However, the mechanisms through which PTH regulates these genes remain unknown. Here we report that PTH stimulated RANKL gene transcription and increased RANKL mRNA stability in murine stromal/osteoblastic cells stably expressing human PTH/PTH-related protein receptor 1. PTH also potently suppressed OPG mRNA in these cells. Cycloheximide did not block the effects of PTH on RANKL but did inhibit the suppression of OPG mRNA. Activation of protein kinase A (PKA) was necessary and sufficient for the effect of PTH on both genes. Conditional expression of a dominant-negative form of the transcription factor CREB, but not c-fos or Runx2, significantly reduced PTH stimulation of RANKL. CREB activity was also required for full stimulation of RANKL by oncostatin M or 1,25-dihydroxyvitamin D 3 . Dominant-negative forms of CREB and c-fos reduced the suppression of OPG by PTH. These results demonstrate that PTH directly stimulates RANKL expression via a PKA-CREB pathway and that CREB may be a central regulator of RANKL expression. Furthermore, they suggest that PTH suppression of OPG involves CREB and c-fos. Parathyroid hormone (PTH)1 maintains calcium homeostasis in part by increasing the production of bone-resorbing osteoclasts to release calcium from the skeleton. It does so indirectly by binding to its G-protein-coupled receptor, PTH/PTHrelated protein receptor 1 (PTHR1), on stromal/osteoblastic cells (1). These cells support osteoclast formation via expression of M-CSF and receptor activator of NFB-ligand (RANKL) (2). Mice deficient in either are incapable of forming osteoclasts, and together these proteins are sufficient to stimulate osteoclast formation in vitro in the absence of stromal/osteoblastic cells (3)(4)(5). In vitro and in vivo studies have demonstrated that the magnitude of osteoclast formation is directly proportional to the level of RANKL expression, whereas M-CSF appears to play primarily a permissive role (4, 6, 7). RANKL binds to its receptor RANK on hematopoietic precursors of osteoclasts and stimulates their differentiation and survival (8). The action of RANKL is blocked by osteoprotegerin (OPG), which functions as a soluble decoy receptor (9). PTH simultaneously stimulates RANKL and inhibits OPG expression in primary cultures of stromal/osteoblastic cells and in bone tissue from parathyroidectomized rats infused with this hormone (10, 11). Based on this, it has been proposed that PTH influences osteoclast formation primarily by regulation of the RANKL/OPG ratio (2). However, the signaling pathways and molecular mechanisms utilized by PTH to regulate these genes remain largely unknown.Binding of PTH to PTHR1 on stromal/osteoblastic cells activates both the protein kinase A (PKA) and protein kinase C (PKC) pathways, and both pathways have been implicated in P...

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Section: Discussionsupporting

confidence: 90%

Parathyroid Hormone Stimulates Receptor Activator of NFκB Ligand and Inhibits Osteoprotegerin Expression via Protein Kinase A Activation of cAMP-response Element-binding Protein

Fu¹,

Jilka²,

Manolagas³

et al. 2002

Journal of Biological Chemistry

207

191

View full text Add to dashboard Cite

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“…The absence of bona fide target sites for VDR action within the first 8 kb of the RankL gene, as reported by us and others [7,8], prompted a more expansive approach to delineate RankL regulatory regions. We therefore used contemporary ChIP/chip analysis in this endeavor.…”

Section: Introductionmentioning

confidence: 83%

“…RankL is synthesized and expressed on the surface of regulatory cells in response to 1,25-dihydroxyvitamin D 3 (1,25(OH) 2 D 3 ) and other stimulators. Despite earlier studies [5,6], regulatory sites within the RankL gene that mediate the actions of 1,25 (OH) 2 D 3 remain unclear [7,8].…”

Section: Introductionmentioning

confidence: 98%

Multiple enhancer regions located at significant distances upstream of the transcriptional start site mediate RANKL gene expression in response to 1,25-dihydroxyvitamin D3

Kim

Yamazaki

Zella

et al. 2007

The Journal of Steroid Biochemistry and Molecular Biology

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One of the primary regulators of Receptor activator of NF-κB ligand (RANKL) is 1,25-dihydoxyvitamin D 3 (1,25(OH) 2 D 3 ). To elucidate the mechanism whereby 1,25(OH) 2 D 3 activates RANKL expression we screened some 300 kb of the RANKL gene locus using a ChIP on chip analysis and identified five potential regulatory regions lying significant distances upstream of the transcription start site (TSS), the farthest over 70 kb from the TSS. A direct ChIP analysis confirmed the presence of the VDR/RXR heterodimer at these sites. The binding of the VDR was associated with histone modification and enhanced entry of RNA polymerase II, indicating an important functional consequence to the localization of these transcription factors in response to 1,25 (OH) 2 D 3 . The region -76kb upstream from the TSS, termed D5, was capable of mediating VDRdependent transcriptional output in response to 1,25(OH) 2 D 3 in luciferase assays. The identified VDRE in this region was able to confer dramatic 1,25(OH) 2 D 3 sensitivity to heterologous promoters. This region was highly evolutionarily conserved and functionally active in the human RANKL gene as well. We propose that the RANKL gene is regulated via multiple enhancers that while located at significant distances from the TSS, likely form a chromatin hub centered on the RankL promoter.

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“…A recent study has shown that Cbfa1 does not regulate RANKL gene activity in stromal/osteoblastic cells, although it binds to the Cbfa1-binding domain of the RANKL promoter (O'Brien et al 2002), while the other observation reveals that overexpression of Cbfa1 in the cells of the osteoblastic lineage increases RANKL expression (Geoffroy et al 2002). It is possible that Cbfa1 may regulate RANKL gene activity in a different manner from that of the other known targets of Cbfa1, such as osteocalcin.…”

Section: Figurementioning

confidence: 99%

Hedgehog signaling enhances core-binding factor a1 and receptor activator of nuclear factor-kappaB ligand (RANKL) gene expression in chondrocytes

Takamoto

Tsuji

Yamashita

et al. 2003

Journal of Endocrinology

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Hedgehog signaling is considered to play a crucial role in chondrogenesis by regulation through a network of cytokine actions, which is not fully understood. We examined the effect of hedgehog signaling on the expression of core-binding factor a1 (Cbfa1), a critical transcription factor for the development of bone and cartilage. Primary chondrocytes prepared from the costal cartilage of newborn mice were treated with N-terminal fragment of recombinant murine sonic hedgehog (rmShh-N). Northern blot analysis indicated that Cbfa1 mRNA expression levels in the chondrocyte cultures were elevated by the treatment with rmShh-N. rmShh-N treatment enhanced 1·8 kb Cbfa1 promoter activity in chondrocytes, suggesting the presence of transcriptional control. As Cbfa1-binding site(s) have been located in the promoter of the receptor activator of nuclear factor-B (RANK) ligand (RANKL) gene, we also examined RANKL expression. rmShh-N treatment upregulated RANKL and RANK mRNA expression levels in chondrocytes. Interestingly, RANKL suppressed the hedgehog enhancement of alkaline phosphatase activity in chondrocytes, suggesting the presence of a link between these signaling molecules. We conclude that hedgehog signaling activates Cbfa1 gene expression through its promoter in chondrocytes, and also activates and interacts with RANKL to maintain cartilage development.

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Cbfa1 does not regulate RANKL gene activity in stromal/osteoblastic cells

Cited by 53 publications

References 32 publications

Parathyroid Hormone Stimulates Receptor Activator of NFκB Ligand and Inhibits Osteoprotegerin Expression via Protein Kinase A Activation of cAMP-response Element-binding Protein

Parathyroid Hormone Stimulates Receptor Activator of NFκB Ligand and Inhibits Osteoprotegerin Expression via Protein Kinase A Activation of cAMP-response Element-binding Protein

Multiple enhancer regions located at significant distances upstream of the transcriptional start site mediate RANKL gene expression in response to 1,25-dihydroxyvitamin D3

Hedgehog signaling enhances core-binding factor a1 and receptor activator of nuclear factor-kappaB ligand (RANKL) gene expression in chondrocytes

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