SEARCH · PubMed Health

Results for “Vitamin D Response Element”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1992

Evaluation of a putative vitamin D response element in the avian calcium binding protein gene.

A primary response of the avian intestine to 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] is increased synthesis of a 28-kD calcium-binding protein, calbindin-D28k (CaBP). This study examined whether 1,25-(OH)2D3 regulates CaBP gene transcription by an interaction of the vitamin D receptor (VDR) with a vitamin D-responsive element (VDRE) in the CaBP promoter. A genomic clone of CaBP containing about 1 kb of 5'-flanking DNA and 13 kb of the structural gene was isolated. 5'-Flanking DNA from -320 to -306 had considerable sequence similarity to VDREs identified in other genes. Indeed, a portion of the CaBP gene containing this region (-743 to +47) linked to a growth hormone reporter construct elicited a 1,25-(OH)2D3-dependent, VDR-dependent increase in reporter expression in transiently transfected chicken embryo fibroblasts. However, deletion analysis demonstrated that the sequences responsible for this induction reside 3' to -133 and the putative VDRE at -320 to -306 was not involved in the response. Furthermore, transfection of heterologous promoter constructs consisting of a Ban I fragment (-354 to -252) linked to the Herpes simplex thymidine kinase promoter revealed no effect of this region on reporter expression. Gel mobility shift analysis confirmed that this putative VDRE in the CaBP promoter was not a high-affinity binding site for VDR. Consequently, functional significance with respect to the primary induction of CaBP by 1,25-(OH)2D3 cannot be ascribed to this region of the CaBP promoter.

Animals↗

PubMed1992

A nuclear protein essential for binding of rat 1,25-dihydroxyvitamin D3 receptor to its response elements.

Recombinant 1,25-dihydroxyvitamin D3 receptor from a baculovirus expression system requires a mammalian-derived nuclear accessory protein for binding to a vitamin D response element (DRE). This was established by electrophoretic mobility shift analyses using radiolabeled DNA probes consisting of DREs from two vitamin D-responsive genes. Mammalian nuclear extract was also required for the binding of wild-type porcine vitamin D receptor to a DRE. Surprisingly, the accessory factor-dependent formation of receptor-DRE complex was independent of exogenous 1,25-dihydroxyvitamin D3. A 59- to 64-kDa accessory protein from porcine intestinal nuclear extract was identified by size-exclusion chromatography. Nuclear extracts from rat liver and kidney contained accessory factor, whereas smaller amounts were detected in heart muscle. Spleen and skeletal muscle contained no detectable accessory factor.

Animals↗

PubMed1992

[Vitamin D3].

With the application of biochemical technique came the discovery that vitamin D is metabolized sequentially to 25-hydroxyvitamin D in liver and then to 1.25-dihydroxyvitamin D (1.25D), the hormonal form of vitamin D, in kidney. The latter process is strictly controlled with the demand of calcium and phosphorus. The produced 1.25D binds its specific receptor probably located in the nuclei. With the application of modern tools of molecular biology came the discovery that vitamin D receptor (VDR), which belongs to steroid receptor family, acquires increased affinity for DNA when it binds to 1.25D and then VDR complexes bind to DNA with its two zinc-finger projections. VDR complexes recognize vitamin D responsive element on DNA, two tandemly repeated hexanucleotide sequences separated by three base pairs. Furthermore, to interact with the VDRE, VDR complexes require nuclear accessory factor, which might be retinoid X receptor (RXR). As above, molecular biology helps us to extend our knowledge in the field of vitamin D.

Calcitriol↗

PubMed1992

The expression of milligram amounts of functional human 1,25-dihydroxyvitamin D3 receptor in a bacterial expression system.

We expressed milligram amounts of functional human 1,25-dihydroxyvitamin D3 receptor in a bacterial expression system in which the cloned cDNA for the hVDR was expressed under the control of bacterial T7 polymerase. The hVDR protein comprised approximately 60% of total bacterial protein. It migrated on polyacrylamide-sodium dodecyl sulfate gels with an M(r) of 48,000. It had the predicted amino acid composition and amino acid sequence analysis. The expressed protein was bound by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) with a Kd in the nanomolar range. It sedimented on sucrose density gradients at 3.5S. Furthermore, the expressed protein bound to the osteocalcin vitamin D response element (VDRE) as assessed by a gel mobility shift assay. The expression of large amounts of hVDR protein should allow for the use of this protein in structure-function and x-ray crystallography studies.

Amino Acid Sequence↗

PubMed1992

Cyclic adenosine 3',5'-monophosphate up-regulates 1,25-dihydroxyvitamin D3 receptor gene expression and enhances hormone action.

We have previously shown that the abundance of vitamin D receptors (VDR) in cultured cells is increased by mitogens such as serum and growth factors, whereas activation of protein kinase-C (PK-C) causes inhibition of VDR gene expression. This study examines the effect of the cAMP-activated protein kinase-A (PK-A) second messenger system on VDR abundance and 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] action. Elevation of intracellular cAMP levels in NIH-3T3 mouse fibroblasts by forskolin or (Bu)2cAMP caused a substantial (8- to 12-fold) increase in VDR abundance, as measured by ligand binding and Western blot analysis. The time course of the forskolin effect on VDR expression was complex. An early rise in VDR abundance occurred at 4 h, followed by a decrease and then a broad secondary rise at 18 h. At the mRNA level, forskolin caused a rapid rise in VDR transcripts after 1 h of exposure, a peak at 2 h, followed by a decline and a subsequent increase at 15 h. Activation of PK-C with the phorbol ester phorbol myristate acetate abolished the forskolin-induced increase in VDR protein and mRNA abundance. NIH-3T3 cells were stably transfected with phOC-CAT, a plasmid carrying a human osteocalcin promoter fragment containing the vitamin D response element fused to the reporter gene chloramphenicol acetyl transferase (CAT). 1,25-(OH)2D3 treatment of transfected cells induced a dose-dependent increase in CAT activity. Up- or down-regulation of VDR in these transfected cells by forskolin or phorbol myristate acetate pretreatment, respectively, resulted in corresponding enhancement or attenuation of 1,25-(OH)2D3-inducible CAT activity.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗

PubMed1992

Vitamin D-responsive protein-DNA interactions at multiple promoter regulatory elements that contribute to the level of rat osteocalcin gene expression.

The observation that vitamin D-mediated enhancement of osteocalcin (OC) gene expression is dependent on and reciprocally related to the level of basal gene expression suggests that an interaction of the vitamin D responsive element (VDRE) with basal regulatory elements of the OC gene promoter contributes to both basal and vitamin D-enhanced transcription. Protein-DNA interactions at the VDRE of the rat OC gene (nucleotides -466 to -437) are reflected by direct sequence-specific and antibody-sensitive binding of the endogenous vitamin D receptor present in ROS 17/2.8 osteosarcoma nuclear protein extracts. In addition, a vitamin D-responsive increase in OC gene transcription is accompanied by enhanced non-vitamin D receptor-mediated protein-DNA interactions in the "TATA" box region (nucleotides -44 to +23), which also contains a potential glucocorticoid responsive element. Evidence for proximity of the VDRE with the basal regulatory elements is provided by two features of nuclear architecture. (i) Nuclear matrix attachment elements in the rat OC gene promoter that bind nuclear matrix proteins with sequence specificity may impose structural constraints on promoter conformation. (ii) Limited micrococcal nuclease digestion and Southern blot analysis indicate that three nucleosomes can be accommodated in the sequence spanning the OC gene VDRE, the OC/CCAAT box (nucleotides -99 to -76), and the TATA/glucocorticoid responsive element, and thereby the potential distance between the VDRE and the basal regulatory elements can be reduced. A model is presented for the contribution of both the VDRE and proximal promoter elements to the enhancement of OC gene transcription in response to vitamin D. The vitamin D receptor plus accessory proteins may function cooperatively with basal regulatory factors to modulate the extent to which the OC gene is transcribed.

Animals↗

PubMed2003

Regulation of the bone-specific osteocalcin gene by p300 requires Runx2/Cbfa1 and the vitamin D3 receptor but not p300 intrinsic histone acetyltransferase activity.

p300 is a multifunctional transcriptional coactivator that serves as an adapter for several transcription factors including nuclear steroid hormone receptors. p300 possesses an intrinsic histone acetyltransferase (HAT) activity that may be critical for promoting steroid-dependent transcriptional activation. In osteoblastic cells, transcription of the bone-specific osteocalcin (OC) gene is principally regulated by the Runx2/Cbfa1 transcription factor and is stimulated in response to vitamin D(3) via the vitamin D(3) receptor complex. Therefore, we addressed p300 control of basal and vitamin D(3)-enhanced activity of the OC promoter. We find that transient overexpression of p300 results in a significant dose-dependent increase of both basal and vitamin D(3)-stimulated OC gene activity. This stimulatory effect requires intact Runx2/Cbfa1 binding sites and the vitamin D-responsive element. In addition, by coimmunoprecipitation, we show that the endogenous Runx2/Cbfa1 and p300 proteins are components of the same complexes within osteoblastic cells under physiological concentrations. We also demonstrate by chromatin immunoprecipitation assays that p300, Runx2/Cbfa1, and 1alpha,25-dihydroxyvitamin D(3) receptor interact with the OC promoter in intact osteoblastic cells expressing this gene. The effect of p300 on the OC promoter is independent of its intrinsic HAT activity, as a HAT-deficient p300 mutant protein up-regulates expression and cooperates with P/CAF to the same extent as the wild-type p300. On the basis of these results, we propose that p300 interacts with key transcriptional regulators of the OC gene and bridges distal and proximal OC promoter sequences to facilitate responsiveness to vitamin D(3).

Acetyltransferases↗

PubMed1992

Contribution of trans-acting factor alleles to normal physiological variability: vitamin D receptor gene polymorphism and circulating osteocalcin.

Osteocalcin, the most abundant noncollagenous protein in bone, is a marker of bone turnover in normal and disease states. Its synthesis is induced by calcitriol, the active hormonal form of vitamin D, through the vitamin D receptor and a specific vitamin D-responsive element in the osteocalcin gene promoter. Serum concentrations of osteocalcin are under strong genetic influence. To ascertain whether variability in circulating osteocalcin levels may reflect allelic variation in the vitamin D receptor gene, we have analyzed the relationship between frequent restriction fragment length polymorphisms (RFLPs, detected by endonucleases Bsm I, EcoRV, and Apa I) that define human vitamin D receptor alleles and serum osteocalcin in a cohort of normal subjects. In 91 Caucasian subjects, RFLPs in the vitamin D receptor gene predicted circulating osteocalcin levels (P less than 0.0001) independent of age or menopause effects. Since the osteocalcin gene and the vitamin D receptor gene are encoded on different chromosomes, the interaction between these two genes occurs in trans. Thus, common alleles of this trans-acting factor, the vitamin D receptor, are functionally different and contribute to "normal" physiological variability in osteocalcin levels. Preliminary analysis in monozygotic and dizygotic twin pairs indicates that the greater diversity in lumbar spine density between the dizygotic pairs can be explained by divergence in vitamin D receptor alleles. Variations in this receptor and other transacting factor genes may confound physiological studies of regulation of target genes and will need to be considered in future human and animal studies. This approach to genetic analysis provides a paradigm for the study of functional variation in trans-acting factors and the role such variation may play in the generation and evolution of physiological diversity.

Alleles↗

PubMed1992

Baculovirus-mediated expression of retinoic acid receptor type gamma in cultured insect cells reveals a difference in specific DNA-binding behavior with the 1,25-dihydroxyvitamin D3 receptor.

The baculovirus genetic expression system has been used to produce murine retinoic acid receptor (RAR) type gamma in Spodoptera frugiperda insect cells and Manduca sexta insect larvae. A hydroxyapatite binding assay revealed production levels of 300 pmol of unoccupied receptor per mg of protein in insect cells, whereas levels from infected insect larvae were found to average 100 pmol of RAR gamma per mg of protein. The cytosolic preparation from infected insect cells exhibited an equilibrium dissociation constant of 2.1 nM as determined by a retinoic acid saturation analysis plotted by the method of Scatchard. A polyclonal antibody directed against RAR gamma recognized the recombinant receptor protein as a 54,000-Da species. Electrophoretic mobility shift analyses demonstrated that protein extracts from RAR gamma-producing insect cells or larvae are capable of retinoic acid responsive element binding. This contrasts with the specific DNA-binding behavior of the insect cell-produced vitamin D receptor, which requires the presence of a mammalian-derived nuclear accessory protein. This distinction between RAR gamma and the vitamin D receptor suggests a difference in the molecular requirements by these two receptors for specific binding of their respective DNA response elements.

Animals↗

PubMed1975

Influence of pharmacological experiments of chemicals and other factors in diets of laboratory animals.

Results derived from animal experimentation depend to a considerable degree on the health and welfare of the animal from which the results are obtained. This, in turn, reflects the quality of housing, care, and nutrition provided the animal. Most diets designed for a particular species provide a reasonable balance of nutrients in quantities sufficient for normal growth and maintenance and reproduction of that species. Under usual conditions of animal feed manufacture, however, concentrations of essential ingredients may vary appreciably in different batches of a formulation made with different lots of natural ingredients, even though the guaranteed analysis shown on the label remains correct. A feed may also contain intentional or unintentional additives and other biologically active components. Variations in the concentrations of essential dietary components, as well as the presence of extraneous materials, can significantly influence the performance of an experimental animal consuming the diet and can thus lead to a biased interpretation of esperimental results. Investigators must consider factors which can result in efficient or inefficient utilization of energy, the variation in prepared diets whether from natural or purified products, and how these can modify the animal and change the response to a given experimental regimen. Proteins, fat, carbohydrates, vitamins, and minerals can all have pharmacological as well as physiological effects on a biological system. The control of vitamin D metabolism and calcium, parathormone, calcitonin among others are important factors subject to dietary modification. A conditioned marginal or frank deficiency of folic acid can result from oral contraceptives and administration of anticonvulsants; if studies are done in animals using these types of chemicals, dietary folate will be highly significant. Newer information about the role of ascorbic acid in activation of lipase and lipid mobilization is of direct concern to those using research animals requiring a source of dietary ascorbic acid. Trace elements, some amino acids, natural enzyme inducers, and toxic contaminants, all of which can affect the response of experimental animals, are highly important to the quality of animal research in pharmacologic investigations.

Amino Acids↗

PubMed1992

Physiological and clinical aspects of vitamin A and its metabolites.

Retinoids, including retinol and retinoic acid (RA), are a group of naturally occurring and synthetic compounds that exhibit vitamin A-like biological activity. They achieve their effects by binding to intracellular proteins. Important sites of action are the nuclear retinoic acid receptors (RAR). These receptors, namely, RAR alpha, RAR beta, and RAR gamma, function as transcription factors by binding to RA-responsive elements (RARE) of multiple genes. Retinoids play a role in vision, embryogenesis, immune modulation, growth and differentiation of normal, premalignant and malignant tissues, the suppression of carcinogenesis, and the inhibition of tumor growth in experimental systems and humans. Reports of the significant antitumor effect of all-trans-RA in acute promyelocytic leukemia and the synthesis of new, less toxic, and more potent retinoids has generated renewed interest in these compounds. Retinoids may have an important role to play in the chemoprevention and therapy of cancer.

Animals↗

PubMed1992

1 beta, 25 (OH)2-vitamin D3 is an antagonist of 1 alpha,25 (OH)2-vitamin D3 stimulated transcaltachia (the rapid hormonal stimulation of intestinal calcium transport).

The steroid hormone 1 alpha,25-dihydroxyvitamin-D3 [1 alpha,25(OH)2D3] stimulates biological responses via both genomic mechanisms and nongenomic mechanisms (opening of voltage-gated Ca2+ channels). We report here that 1 beta, 25(OH)2-vitamin-D3 (a) is devoid of activity as an agonist for transcaltachia, (b) is a potent stereospecific antagonist of 1 alpha,25 (OH)2D3 stimulation of the nongenomic transcaltachia response and also (c) has less than 1% the ability of 1 alpha,25(OH)2D3 to bind to the chick intestinal nuclear 1 beta,25(OH)2D3 receptor. We conclude that the membrane response element(s) which generates the nongenomic response of transcaltachia has a different ligand specificity than the classic nuclear 1 alpha, 25(OH)2D3 receptor.

Animals↗

PubMed1992

Retinoid X receptor interacts with nuclear receptors in retinoic acid, thyroid hormone and vitamin D3 signalling.

Cellular responsiveness to retinoic acid and its metabolites is conferred through two structurally and pharmacologically distinct families of receptors: the retinoic acid receptors (RAR) and the retinoid X receptors (RXR). Here we report that the transcriptional activity of RAR and RXR can be reciprocally modulated by direct interactions between the two proteins. RAR and RXR have a high degree of cooperativity in binding to target DNA, consistent with previous reports indicating that the binding of either RAR or RXR to their cognate response elements is enhanced by factors present in nuclear extracts. RXR also interacts directly with and enhances the binding of nuclear receptors conferring responsiveness to vitamin D3 and thyroid hormone T3; the DNA-binding activities of these receptors are also stimulated by the presence of nuclear extracts. Together these data indicate that RXR has a central role in multiple hormonal signalling pathways.

Animals↗

PubMed1992

1,25(OH)2-vitamin D3, a steroid hormone that produces biologic effects via both genomic and nongenomic pathways.

The hormonally active form of vitamin D is 1,25(OH)2-vitamin D3 [1,25(OH)2D3]. This seco-steroid is the key mediator of the vitamin D endocrine system which produces biological effects in over 28 target tissues. In these target tissues, the biological responses may be generated both by a signal transduction mechanism which involves a nuclear receptor for 1,25(OH)2D3 that modulates gene transcription or a signal transduction pathway which involves rapid opening of Ca2+ channels which are externally located on the plasma membrane. This paper reviews the evidence in support of the pleiotropic effects of this steroid hormone and presents evidence that the receptor of the genomic effects is likely to be separate from the receptor/membrane recognition element which initiates the rapid nongenomic biological effects.

Animals↗

PubMed1992

Autogenous regulation of ethanolamine utilization by a transcriptional activator of the eut operon in Salmonella typhimurium.

The genes required for use of ethanolamine as a carbon and nitrogen source are encoded by a single operon (eut) whose expression is induced by the simultaneous presence of both ethanolamine and cobalamin (vitamin B12). The action of B12 as an inducer of this operon reflects the fact that this cofactor is required by the degradative enzyme ethanolamine lyase (eutBC). The eutR gene encodes a protein that activates transcription of the eut operon in response to the simultaneous presence of B12 and ethanolamine. The eutR gene is expressed by a weak constitutive promoter activity (PII) and by the main regulated promoter (PI). Because it is encoded within the operon that it activates, the EutR protein controls its own production. Initial induction of the eut operon by ethanolamine plus B12 causes an increase in expression of the eutR gene; this increase acts as part of a positive feedback loop that is required for maximal operon expression. Because of this mode of regulation, constitutive regulatory mutations, described here, include mutations that generate new internal promoters and thereby increase the basal level of eutR gene expression. In mutants with an increased level of activator protein, each inducer (B12 or ethanolamine), presented singly, is sufficient for partial operon induction.

Bacterial Proteins↗

PubMed1977

Interaction of nutrition and infection: plans for future research.

Future research concerning the interactions between infectious disease and nutritional status must extend our available knowledge concerning these two major problem areas. Critical studies must be designed in animal models as well as in man. The effects of malnutrition on immune responsiveness must be studied. Key information is lacking with respect to the utilization of host energy and protein during infection. Alterations in body chemistry are especially important in protracted diarrheal and respiratory diseases of children. A concensus has not yet been reached concerning the optimal approach to iron nutritional needs during infection or to those of other trace nutrients including the vitamins. Research needs in each of these areas are listed.

Animals↗

PubMed1977

Improved medium for clonal growth of human diploid fibroblasts at low concentrations of serum protein.

A new medium (MCDB 104) has been developed which will support clonal growth of WI-38 cells at concentrations of serum protein as low as 25 micrograms per ml (equivalent to 0.05% serum). The principal factors responsible for reduction of the protein requirement are: (a) adjustment of all nutrient concentrations in medium F12 to experimentally determined optimum values for WI-38 cells; (b) supplementation with trace elements; (c) replacement of hypoxanthine and folic acid with adenine and folinic acid; and (d) coating of the culture surface with polylysine. Individually, many of these modifications exert only a small effect on cellular growth at reduced protein concentrations, but collectively their effect has been very substantial. Other strains of fibroblast-like human diploid cells from amniotic fluid, fetal lung and newborn foreskin also will grow at reduced concentrations of serum protein in the new medium.

Adenine↗

PubMed1992

Regulation of 1,25-dihydroxyvitamin D3 receptor gene expression by parathyroid hormone and cAMP-agonists.

We studied the effect of parathyroid hormone (PTH) and activation of the cAMP signal pathway on vitamin D receptor (VDR) mRNA levels in the phenotypically osteoblast cell line UMR 106. PTH caused a time- and dose-dependent increase of the VDR mRNA content with a maximum after 2 h. After 24 h the VDR mRNA level in PTH-treated cells returned to control level. In contrast, the 1,25-dihydroxyvitamin D3 (1,25(OH)2D3)-induced increase in VDR mRNA did not decline after 24 h. Inhibition of transcription with actinomycin D (10 micrograms/ml) completely abolished the PTH-induced increase of VDR mRNA and inhibition of translation with cycloheximide (1 microgram/ml) resulted in superinduction of VDR mRNA. The role of cAMP in the induction of VDR mRNA was studied with several agents acting via the cAMP pathway. Incubation for 2 and 4 h with forskolin, Bt2cAMP, PTHrP or prostaglandin E2 caused an increase in the level of VDR mRNA comparable to that caused by PTH. The calcium ionophore A23187 did not affect VDR mRNA level. The present study demonstrates that PTH and activation of the cAMP signal pathway cause up-regulation of VDR via induction of VDR gene expression. The effect of cAMP on the VDR gene is suggestive for a cAMP responsive element in the VDR gene.

Animals↗