scholarly journals Activation of Receptor Activator of NF-κB Ligand Gene Expression by 1,25-Dihydroxyvitamin D3 Is Mediated through Multiple Long-Range Enhancers

2006 ◽  
Vol 26 (17) ◽  
pp. 6469-6486 ◽  
Author(s):  
Sungtae Kim ◽  
Miwa Yamazaki ◽  
Lee A. Zella ◽  
Nirupama K. Shevde ◽  
J. Wesley Pike
Keyword(s):  
Gene Expression ◽  
Vitamin D ◽  
Rna Polymerase Ii ◽  
Transcriptional Activation ◽  
Molecular Mechanisms ◽  
Chromatin Modification ◽  
Response Element ◽  
Dihydroxyvitamin D3 ◽  
Specific Element ◽  
Dihydroxyvitamin D

ABSTRACT RANKL is a tumor necrosis factor (TNF)-like factor secreted by mesenchymal cells, osteoblast derivatives, and T cells that is essential for osteoclastogenesis. In osteoblasts, RANKL expression is regulated by two major calcemic hormones, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and parathyroid hormone (PTH), as well as by several inflammatory/osteoclastogenic cytokines; the molecular mechanisms for this regulation are unclear. To identify such mechanisms, we screened a DNA microarray which tiled across the entire mouse RankL gene locus at a 50-bp resolution using chromatin immunoprecipitation (ChIP)-derived DNA precipitated with antibodies to the vitamin D receptor (VDR) and the retinoid X receptor (RXR). Five sites of dimer interaction were observed on the RankL gene centered at 16, 22, 60, 69, and 76 kb upstream of the TSS. These regions contained binding sites for not only VDR and RXR, but also the glucocorticoid receptor (GR). The most distant of these regions, termed the distal control region (RL-DCR), conferred both VDR-dependent 1,25(OH)2D3 and GR-dependent glucocorticoid (GC) responses. We mapped these activities to an unusual but functionally active vitamin D response element and to several potential GC response elements located over a more extensive region within the RL-DCR. An evolutionarily conserved region within the human RANKL gene contained a similar vitamin D response element and exhibited an equivalent behavior. Importantly, hormonal activation of the RankL gene was also associated with chromatin modification and RNA polymerase II recruitment. Our studies demonstrate that regulation of RankL gene expression by 1,25(OH)2D3 is complex and mediated by at least five distal regions, one of which contains a specific element capable of mediating direct transcriptional activation.

scholarly journals Importance of apical membrane delivery of 1,25-dihydroxyvitamin D3 to vitamin D-responsive gene expression in the colon

2012 ◽  
Vol 303 (7) ◽  
pp. G870-G878 ◽  
Author(s):  
Nicholas J. Koszewski ◽  
Ronald L. Horst ◽  
Jesse P. Goff
Keyword(s):  
Gene Expression ◽  
Vitamin D ◽  
Intestinal Tract ◽  
Apical Membrane ◽  
Dihydroxyvitamin D3 ◽  
Surgical Ligation ◽  
Dihydroxyvitamin D ◽  
Equimolar Dose ◽  
Dose Dependent Increase ◽  
Dose Dependent

Synthetic conjugation of a glucuronide to 1,25-dihydroxyvitamin D3 (1,25D3) to produce β-25-monoglucuronide-1,25D3 (βGluc-1,25D3) renders the hormone biologically inactive and resistant to mammalian digestive enzymes. However, β-glucuronidase produced by bacteria in the lower intestinal tract can cleave off the glucuronide, releasing the active hormone. In mice given a single oral dose of 1,25D3, 24-hydroxylase (Cyp24a1) gene expression was strongly enhanced in the duodenum, but not in the colon, despite circulating concentrations of 1,25D3 that peaked at ∼3.0 nmol/l. In contrast, in mice treated with an equimolar dose of βGluc-1,25D3, Cyp24a1 gene expression increased 700-fold in the colon but was significantly weaker in the duodenum compared with mice treated with 1,25D3. Similar results were observed with another vitamin D-dependent gene. When administered subcutaneously, 1,25D3 weakly stimulated colon Cyp24a1 gene expression while βGluc-1,25D3 again resulted in strong enhancement. Surgical ligation to block passage of ingesta beyond the upper intestinal tract abolished upregulation of colon Cyp24a1 gene expression by orally and subcutaneously administered βGluc-1,25D3. Feeding βGluc-1,25D3 for 5 days revealed a linear, dose-dependent increase in colon Cyp24a1 gene expression but did not significantly increase plasma 1,25D3 or calcium concentrations. This study indicates that the colon is relatively insensitive to circulating concentrations of 1,25D3 and that the strongest gene enhancement occurs when the hormone reaches the colon via the lumen of the intestinal tract. These findings have broad implications for the use of vitamin D compounds in colon disorders and set the stage for future therapeutic studies utilizing βGluc-1,25D3 in their treatment.

Inhibitory effect of NF-κB on 1,25-dihydroxyvitamin D3 and retinoid X receptor function

2000 ◽  
Vol 279 (1) ◽  
pp. E213-E220 ◽  
Author(s):  
Paul K. Farmer ◽  
Xiaofei He ◽  
M. Lienhard Schmitz ◽  
Janet Rubin ◽  
Mark S. Nanes
Keyword(s):  
Vitamin D ◽  
Dna Sequences ◽  
Transcriptional Activation ◽  
Inhibitory Effect ◽  
Retinoid X Receptor ◽  
Mobility Shift ◽  
Dihydroxyvitamin D3 ◽  
Dihydroxyvitamin D ◽  
Tnf Α ◽  
Factor Α

Responsiveness to 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] may be diminished in osteoporosis and inflammatory arthritis. The inflammatory cytokine tumor necrosis factor-α (TNF-α) is produced in excess in these disorders and has been shown to decrease osteoblast transcriptional responsiveness to vitamin D and to inhibit the binding of the vitamin D receptor (VDR) and its nuclear partner the retinoid X receptor (RXR) to DNA. Previous studies have shown that a vitamin D (VDRE) or retinoid X DNA response element (RXRE) is sufficient to confer TNF-α inhibition of vitamin D or retinoid-stimulated transcription in the absence of known TNF-α-responsive DNA sequences. We tested the hypothesis that the TNF-α-stimulated transcription factor nuclear factor (NF)-κB could, in part, mediate TNF-α action by inhibiting the transcriptional potency of the VDR and RXR at their cognate cis regulatory sites. Osteoblastic ROS 17/2.8 cells transfected with a dose of NF-κB comparable to that stimulated by TNF-α decreased 1,25(OH)2D3-stimulated transcription. This inhibitory effect of NF-κB was not observed on basal transcription of a heterologous reporter in the absence of the VDRE. The effects of NF-κB and TNF-α were comparable but not additive. COS-7 cells were cotransfected with reporters under the regulation of VDRE or RXRE along with vectors expressing VDR, RXR, and NF-κB nuclear proteins. Reconstituted NF-κB and the NF-κB subunit p65 alone, but not p50, dose dependently suppressed basal and ligand-stimulated transcription. p65 overexpression completely abrogated enhanced VDRE-mediated transcriptional activity in response to 1,25(OH)2D3. Electrophoretic mobility shift experiments did not reveal a direct effect of recombinant NF-κB or its individual subunits on the binding of heterodimeric VDR-RXR to DNA. These results suggest that TNF-α inhibition of hormone-stimulated transcriptional activation may be mediated by activation of NF-κB. In contrast, the inhibitory effect of TNF-α on binding of receptors to DNA is unlikely to be mediated by NF-κB and is not necessary for inhibition of transcription.

scholarly journals The Mediator Subunit MED16 Transduces NRF2-Activating Signals into Antioxidant Gene Expression

2015 ◽  
Vol 36 (3) ◽  
pp. 407-420 ◽  
Author(s):  
Hiroki Sekine ◽  
Keito Okazaki ◽  
Nao Ota ◽  
Hiroki Shima ◽  
Yasutake Katoh ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcriptional Activation ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Antioxidant Response ◽  
Wild Type ◽  
Antioxidant Genes ◽  
Antioxidant Gene Expression

The KEAP1-NRF2 system plays a central role in cytoprotection. NRF2 is stabilized in response to electrophiles and activates transcription of antioxidant genes. Although robust induction of NRF2 target genes confers resistance to oxidative insults, how NRF2 triggers transcriptional activation after binding to DNA has not been elucidated. To decipher the molecular mechanisms underlying NRF2-dependent transcriptional activation, we purified the NRF2 nuclear protein complex and identified the Mediator subunits as NRF2 cofactors. Among them, MED16 directly associated with NRF2. Disruption ofMed16significantly attenuated the electrophile-induced expression of NRF2 target genes but did not affect hypoxia-induced gene expression, suggesting a specific requirement for MED16 in NRF2-dependent transcription. Importantly, we found that 75% of NRF2-activated genes exhibited blunted inductions by electrophiles inMed16-deficient cells compared to wild-type cells, which strongly argues that MED16 is a major contributor supporting NRF2-dependent transcriptional activation. NRF2-dependent phosphorylation of the RNA polymerase II C-terminal domain was absent inMed16-deficient cells, suggesting that MED16 serves as a conduit to transmit NRF2-activating signals to RNA polymerase II. MED16 indeed turned out to be essential for cytoprotection against oxidative insults. Thus, the KEAP1-NRF2-MED16 axis has emerged as a new regulatory pathway mediating the antioxidant response through the robust activation of NRF2 target genes.

Molecular mechanisms for somatostatin inhibition of c-fos gene expression

1997 ◽  
Vol 272 (4) ◽  
pp. G721-G726 ◽  
Author(s):  
A. Todisco ◽  
Y. Takeuchi ◽  
J. Yamada ◽  
J. I. Sadoshima ◽  
T. Yamada
Keyword(s):  
Gene Expression ◽  
Transcriptional Activation ◽  
Molecular Mechanisms ◽  
Early Gene ◽  
Luciferase Reporter ◽  
Luciferase Reporter Gene ◽  
Response Element ◽  
Erk Phosphorylation ◽  
Extracellular Signal ◽  
Erk Activity

We reported previously that somatostatin inhibits the expression of the immediate early gene c-fos. Accordingly, we characterized the molecular mechanisms by which somatostatin inhibits c-fos gene expression. Because growth factors activate c-fos through a region of its promoter known as the serum response element [SRE; base pairs (bp) -357 to -276] we transfected rat pituitary adenoma cells (GH3) with plasmids containing the SRE or the SRE core fragment (bp -320 to -298) upstream of the luciferase reporter gene. Epidermal growth factor (EGF) stimulated SRE-luciferase activity, and this effect was inhibited by somatostatin and by the analog MK-678. Identical results were obtained with the SRE core plasmid, demonstrating that the sequence between bp -320 and -298 of the c-fos promoter is a somatostatin response element. Because the extracellular signal-regulated protein kinases (ERKs) induce the SRE via phosphorylation of transcription factors such as Elk-1, we examined the effect of somatostatin on ERK phosphorylation and activation. EGF stimulated tyrosine phosphorylation of ERK2, and MK-678 attenuated this effect. In experiments using in-gel kinase assays, MK-678 also inhibited EGF-stimulated ERK activity via a pertussis toxin sensitive pathway, and this effect resulted in inhibition of Elk-1 transcriptional activity. Our data suggest that one mechanism of somatostatin action involves inhibition of ERK activity, Elk-1 phosphorylation and transcriptional activation, and ultimately c-fos gene transcription.

scholarly journals Placental uptake and metabolism as determinants of pregnancy vitamin D status

2021 ◽  
Author(s):  
Brogan Ashley ◽  
Claire Simner ◽  
Antigoni Manousopoulou ◽  
Carl Jenkinson ◽  
Felicity Hey ◽  
...  
Keyword(s):  
Vitamin D ◽  
Transcriptional Activation ◽  
Inflammatory Responses ◽  
Transcriptional Response ◽  
Dihydroxyvitamin D3 ◽  
Placental Perfusion ◽  
Placental Function ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
Underlying Mechanisms

Pregnancy 25-hydroxyvitamin D (25(OH)D) concentrations are associated with maternal and fetal health outcomes, but the underlying mechanisms have not been elucidated. Using physiological human placental perfusion approaches and intact villous explants we demonstrate a role for the placenta in regulating the relationships between maternal 25(OH)D concentrations and fetal physiology. Here, we demonstrate active placental uptake of 25(OH)D3 by endocytosis and placental metabolism of 25(OH)D3 into 24,25-dihydroxyvitamin D3 and active 1,25-dihydroxyvitamin D [1,25(OH)2D3], with subsequent release of these metabolites into both the fetal and maternal circulations. Active placental transport of 25(OH)D3 and synthesis of 1,25(OH)2D3 demonstrate that fetal supply is dependent on placental function rather than solely the availability of maternal 25(OH)D3. We demonstrate that 25(OH)D3 exposure induces rapid effects on the placental transcriptome and proteome. These map to multiple pathways central to placental function and thereby fetal development, independent of vitamin D transfer, including transcriptional activation and inflammatory responses. Our data suggest that the underlying epigenetic landscape helps dictate the transcriptional response to vitamin D treatment. This is the first quantitative study demonstrating vitamin D transfer and metabolism by the human placenta; with widespread effects on the placenta itself. These data show complex and synergistic interplay between vitamin D and the placenta, and inform possible interventions to optimise placental function to better support fetal growth and the maternal adaptations to pregnancy.

scholarly journals 1,25-Dihydroxyvitamin D3 and Development of Tuberculosis in Cattle

2003 ◽  
Vol 10 (6) ◽  
pp. 1129-1135 ◽  
Author(s):  
S. G. Rhodes ◽  
L. A. Terry ◽  
J. Hope ◽  
R. G. Hewinson ◽  
H. M. Vordermeier
Keyword(s):  
Vitamin D ◽  
T Cell ◽  
Mononuclear Cells ◽  
T Cell Proliferation ◽  
Accessory Cell ◽  
Dihydroxyvitamin D3 ◽  
Dihydroxyvitamin D ◽  
Cell Responses ◽  
1,25 Dihydroxyvitamin D ◽  
Accessory Cells

ABSTRACT This report describes the presence and activity of 1,25-dihydroxyvitamin D3 (1,25-D3) in experimental bovine tuberculosis. Animals that went on to develop tuberculous lesions exhibited a rapid transient increase in serum 1,25-D3 within the first 2 weeks following infection with Mycobacterium bovis. 1,25-D3-positive mononuclear cells were later identified in all tuberculous granulomas by immunohistochemical staining of postmortem lymph node tissue. These results suggest a role for 1,25-D3 both at the onset of infection and in the development of the granuloma in these infected animals. Using a monoclonal antibody to the vitamin D receptor (VDR) as a VDR agonist, we confirmed that activation of the vitamin D pathway profoundly depresses antigen-specific, but not mitogenic, bovine peripheral blood T-cell responses (proliferation and gamma interferon production). Investigation of the mechanism of this suppression showed that the VDR antibody modified the expression of CD80 by accessory cells, such that a significant positive correlation between T-cell proliferation and accessory cell CD80 emerged.

scholarly journals Integrative In Silico and In Vitro Transcriptomics Analysis Revealed Gene Expression Changes and Oncogenic Features of Normal Cholangiocytes after Chronic Alcohol Exposure

2019 ◽  
Vol 20 (23) ◽  
pp. 5987
Author(s):  
Suthipong Chujan ◽  
Tawit Suriyo ◽  
Jutamaad Satayavivad
Keyword(s):  
Gene Expression ◽  
Rna Polymerase Ii ◽  
Molecular Mechanisms ◽  
Function Analysis ◽  
Alcohol Exposure ◽  
Gene Expression Omnibus ◽  
Regulation Of Transcription ◽  
Chronic Alcohol ◽  
Chronic Alcohol Exposure

Cholangiocarcinoma (CCA) is a malignant tumor originating from cholangiocyte. Prolonged alcohol consumption has been suggested as a possible risk factor for CCA, but there is no information about alcohol’s mechanisms in cholangiocyte. This study was designed to investigate global transcriptional alterations through RNA-sequencing by using chronic alcohol exposure (20 mM for 2 months) in normal human cholangiocyte MMNK-1 cells. To observe the association of alcohol induced CCA pathogenesis, we combined differentially expressed genes (DEGs) with computational bioinformatics of CCA by using publicly gene expression omnibus (GEO) datasets. For biological function analysis, Gene ontology (GO) analysis showed biological process and molecular function related to regulation of transcription from RNA polymerase II promoter, while cellular component linked to the nucleoplasm. KEGG pathway presented pathways in cancer that were significantly enriched. From KEGG result, we further examined the oncogenic features resulting in chronic alcohol exposure, enhanced proliferation, and migration through CCND-1 and MMP-2 up-regulation, respectively. Finally, combined DEGs were validated in clinical data including TCGA and immunohistochemistry from HPA database, demonstrating that FOS up-regulation was related to CCA pathogenesis. This study is the first providing more information and molecular mechanisms about global transcriptome alterations and oncogenic enhancement of chronic alcohol exposure in normal cholangiocytes.

scholarly journals The grapevine R2R3-type MYB transcription factor VdMYB1 positively regulates defense responses by activating the stilbene synthase gene 2 (VdSTS2)

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Yihe Yu ◽  
Dalong Guo ◽  
Guirong Li ◽  
Yingjun Yang ◽  
Guohai Zhang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcriptional Activation ◽  
Molecular Mechanisms ◽  
Plant Protection ◽  
Defense Responses ◽  
Stilbene Synthase ◽  
Myb Transcription Factor ◽  
Wide Range ◽  
Grapevine Leaves

Abstract Background Resveratrol is a naturally occurring plant stilbene that exhibits a wide range of valuable biological and pharmacological properties. Although the beneficial effects of trans-resveratrol to human health and plant protection against fungal pathogens and abiotic stresses are well-established, yet little is known about the molecular mechanisms regulating stilbene biosynthesis in plant defense progress. Results Here, we cloned and identified the Chinese wild grape (Vitis davidii) R2R3-MYB transcription factor VdMYB1, which activates defense responses against invading pathogen. VdMYB1 transcripts were significantly upregulated after inoculation with the grapevine powdery mildew fungus Erysiphe necator (Schw.) Burr. Transient expression analysis using onion epidermal cells and Arabidopsis thaliana protoplasts showed that VdMYB1 was localized in the nucleus. Yeast one-hybrid assays revealed that VdMYB1 acts as a transcriptional activator. Grapevine leaves transiently overexpressing VdMYB1 showed a lower number of fungal conidiophores compared with wild-type leaves. Overexpression of VdMYB1 in grapevine leaves did not alter the expression of genes in salicylic acid- and jasmonate-dependent pathways, but affected the expression of stilbene synthase (STS) genes, key regulators of flavonoid metabolism. Results of electrophoretic mobility shift assays and in vivo transcriptional activation assays showed that VdMYB1 binds to the MYB binding site (MYBBS) in the STS2 gene promoter, thus activating STS2 transcription. In heterologous expression assays using tobacco leaves, VdMYB1 activated STS2 gene expression and increased the accumulation of resveratrol. Conclusions Our study showed that VdMYB1 activates STS2 gene expression to positively regulate defense responses, and increases the content of resveratrol in leaves.

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