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Taylor CL, Patterson KY, Roseland JM, Wise SA, Merkel JM, Pehrsson PR, Yetley EA. Including food 25-hydroxyvitamin D in intake estimates may reduce the discrepancy between dietary and serum measures of vitamin D status. J Nutr 2014; 144:654-9. [PMID: 24623845 PMCID: PMC3985821 DOI: 10.3945/jn.113.189811] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The discrepancy between the commonly used vitamin D status measures-intake and serum 25-hydroxyvitamin D [25(OH)D] concentrations--has been perplexing. Sun exposure increases serum 25(OH)D concentrations and is often used as an explanation for the higher population-based serum concentrations in the face of apparently low vitamin D intake. However, sun exposure may not be the total explanation. 25(OH)D, a metabolite of vitamin D, is known to be present in animal-based foods. It has been measured and reported only sporadically and is not currently factored into U.S. estimates of vitamin D intake. Previously unavailable preliminary USDA data specifying the 25(OH)D content of a subset of foods allowed exploration of the potential change in the reported overall vitamin D content of foods when the presence of 25(OH)D was included. The issue of 25(OH)D potency was addressed, and available commodity intake estimates were used to outline trends in projected vitamin D intake when 25(OH)D in foods was taken into account. Given the data available, there were notable increases in the total vitamin D content of a number of animal-based foods when potency-adjusted 25(OH)D was included, and in turn there was a potentially meaningful increase (1.7-2.9 μg or 15-30% of average requirement) in vitamin D intake estimates. The apparent increase could reduce discrepancies between intake estimates and serum 25(OH)D concentrations. The relevance to dietary interventions is discussed, and the need for continued exploration regarding 25(OH)D measurement is highlighted.
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Affiliation(s)
- Christine L. Taylor
- Office of Dietary Supplements, National Institutes of Health, Bethesda, MD,To whom correspondence should be addressed. E-mail:
| | | | - Janet M. Roseland
- Nutrient Data Laboratory, Agricultural Research Service, USDA, Beltsville, MD; and
| | - Stephen A. Wise
- National Institute of Standards and Technology, Department of Commerce, Gaithersburg, MD
| | - Joyce M. Merkel
- Office of Dietary Supplements, National Institutes of Health, Bethesda, MD
| | - Pamela R. Pehrsson
- Nutrient Data Laboratory, Agricultural Research Service, USDA, Beltsville, MD; and
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Pardo VG, Facchinetti MM, Curino A, Boland R, de Boland AR. Age-related alteration of 1alpha,25(OH)2-vitamin D3-dependent activation of p38 MAPK in rat intestinal cells. Biogerontology 2006; 8:13-24. [PMID: 16855859 DOI: 10.1007/s10522-006-9031-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Accepted: 05/10/2006] [Indexed: 01/17/2023]
Abstract
In intestinal cells, 1alpha,25(OH)(2)-vitamin D(3) (1alpha,25(OH)(2)D(3)) regulates gene expression via the specific intracellular vitamin D receptor and induces fast non-transcriptional responses involving stimulation of transmembrane signal transduction pathways. In the present study, we analyzed, for the first time, alterations in p38 MAPK response to 1alpha,25(OH)(2)D(3) in rat enterocytes with ageing. In enterocytes from young rats, the hormone increased, in a time- and dose-dependent fashion, the phosphorylation of p38 MAPK, peaking at 3 min (+2-fold). Basal levels of p38 MAPK phosphorylation were lower in enterocytes from old rats and the hormone response was greatly diminished (+0.5-fold at 3 min). p38 MAPK phosphorylation impairment in old animals was not related to significant changes of the kinase protein expression and do not explain the decreased response to 1alpha,25(OH)(2)D(3). Extracellular and intracellular Ca(2+) chelation or c-Src pharmacological inhibition suppressed hormone activation of p38 MAPK in both, young and aged rats, demonstrating that Ca(2+) and the non-receptor tyrosine kinase c-Src are required for full activation of p38 MAPK in cells stimulated with 1alpha,25(OH)(2)D(3). Two other vitamin D(3) metabolites, 25(OH)D(3) and 24,25(OH)(2)D(3, )also enhanced p38 phosphorylation, and to a similar extent than 1alpha,25(OH)(2)D(3), an ability that is lost with ageing. Enterocyte exposure to the hormone also resulted in the rapid induction of c-fos protein (peaking at 5 min, +3-fold) and to a greater extent than that of mRNA induction. With ageing, 1alpha,25(OH)(2)D(3)-dependent increase of c-fos protein level was diminished, but c-fos mRNA expression was not different from young animals. Impairment of 1alpha,25(OH)(2)D(3) activation of p38 MAPK upon ageing and abnormal hormone regulation of the c-fos oncoprotein synthesis may affect intestinal cell function.
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Affiliation(s)
- Verónica Gonzalez Pardo
- Departamento de Biología, Bioquímica & Farmacia, Universidad Nacional del Sur, San Juan 670, Bahia Blanca 8000, Argentina
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Pardo VG, Boland R, de Boland AR. 1α,25(OH)2-Vitamin D3 stimulates intestinal cell p38 MAPK activity and increases c-Fos expression. Int J Biochem Cell Biol 2006; 38:1181-90. [PMID: 16483831 DOI: 10.1016/j.biocel.2005.12.018] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Revised: 11/14/2005] [Accepted: 12/21/2005] [Indexed: 11/20/2022]
Abstract
In intestinal cells, as in other target cells, the steroid hormone 1alpha,25(OH)(2)-Vitamin D(3) (1alpha,25(OH)(2)D(3)) regulates gene expression via the specific intracellular Vitamin D receptor and induces fast non-transcriptional responses involving stimulation of transmembrane signal transduction pathways. We have previously shown that the hormone activates the extracellular signal-regulated mitogen-activated protein (MAP) kinase isoforms ERK1 and ERK2 in rat intestinal cells. In the present study, we have demonstrated that 1alpha,25(OH)(2)D(3) also induces the phosphorylation and activation of p38 MAPK in these cells. The hormone effects were time and dose-dependent, with maximal stimulation at 2min (+3-fold) and 1nM. 1alpha,25(OH)(2)D(3)-dependent p38 phosphorylation was suppressed by SB 203580, a selective inhibitor of p38 MAPK. Ca(2+) chelation with EGTA, inhibition of the c-Src-tyrosine kinase family with PP1 or protein kinase A (PKA) with Rp-cAMP, attenuated hormone activation of p38 MAPK. The physiological significance of 1alpha,25(OH)(2)D(3)-dependent activation of ERK1/2 and p38 MAP kinases was addressed by monitoring c-Fos expression. Incubation of intestinal cells with the hormone was followed by a rapid induction of c-Fos expression which was blocked by SB 203580 and partially suppressed by the ERK1/2 inhibitor PD 98059. Our results suggest that 1alpha,25(OH)(2)D(3) activates p38 MAPK, involving Ca(2+), c-Src and PKA as upstream regulators, and that p38 MAPK has a central role in hormone-induction of the oncoprotein c-Fos in rat intestinal cells.
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Affiliation(s)
- Verónica González Pardo
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, 8000 Bahía Blanca, Argentina
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Larsson B, Nemere I. Effect of growth and maturation on membrane-initiated actions of 1,25-dihydroxyvitamin D3?II: Calcium transport, receptor kinetics, and signal transduction in intestine of female chickens. J Cell Biochem 2003; 90:901-13. [PMID: 14624450 DOI: 10.1002/jcb.10696] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We recently reported (Larsson and Nemere [2003]: Endocrinology 144:1726) the effects of growth and maturation on 1,25(OH)2D3-membrane initiated effects in the intestine of male chickens. Here we extend our observations to studies on females with two stages of high calcium demand: growth (7-14 weeks) and egg laying (28-58 weeks). The rapid stimulatory effect of 130 pM 1,25(OH)2D3 on calcium transport was assessed as a physiological response in perfused duodena of 7-, 14-, 28-, and 58-week-old chickens, and determined to be 308%, 184%, 170%, and 153%, respectively, of corresponding controls after 40 min. Saturation analyses of [3H]1,25(OH)2D3 binding to nuclear vitamin D receptor (VDR) indicated an absence of cooperative binding, no changes in dissociation constant (Kd) with age, and an increase in maximum binding capacity (Bmax) between 7-week birds and older age groups. Analyses of saturable binding of [3H]1,25(OH)2D3 to the membrane associated rapid response steroid binding protein (1,25D3-MARRS bp) in basal lateral membranes (BLM), indicated cooperative binding, and an increase in both Bmax and Kd with age. No changes in the age-related expression of 1,25D3-MARRS bp were found, as judged by Western analyses, suggesting that a shift in ligand binding to lower affinity membrane components accounted for the increase in calculated Bmax. Basal levels of protein kinase C (PKC) activity decreased with age, as did hormone enhancement of activity. Basal levels of protein kinase A (PKA) activity remained constant with age, while the magnitude of hormone stimulation increased. Comparison of dose-response curves for ion transport and kinase activities in 7-week chicks suggested that PKC mediates phosphate transport while PKA mediates calcium transport. Thus, the age-related loss of calcium transport is most likely related to loss of PKC-mediated phosphate transport.
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Affiliation(s)
- Birgitta Larsson
- Utah State University, Department of Nutrition and Food Sciences and the Biotechnology and Genomics Research Center, Logan, Utah 84322-8700, USA
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Ovesen L, Brot C, Jakobsen J. Food contents and biological activity of 25-hydroxyvitamin D: a vitamin D metabolite to be reckoned with? ANNALS OF NUTRITION & METABOLISM 2003; 47:107-13. [PMID: 12743460 DOI: 10.1159/000070031] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Only a limited number of foods naturally contain vitamin D such as fish, meat and offal, and eggs, and milk and dairy products. However, all these foods in addition contain the metabolite 25-hydroxyvitamin D (25OHD). From the few systematic studies which have been performed the food contents of 25OHD in animal foods are usually low but vary. Contents are typically very low in milk and fish (<0.1 microg/100 g), somewhat higher in meat and offal (0.2-0.4 microg/100 g) and up to 1 microg/100 g in egg yolk. It has been demonstrated that 25OHD is absorbed better and faster from the diet than native vitamin D and has metabolic effects of its own in regulating cell growth and calcium metabolism. Thus, the biological activity of 25OHD is greater than that of native vitamin D. However, there is as yet no consensus on the conversion factor that should be used for 25OHD to calculate vitamin D activity. Depending on the testing system used the factor varies from 1.5 to 5. If food contents and the higher potency of 25OHD are not included in dietary intake surveys, true vitamin D intake will be underestimated.
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Affiliation(s)
- Lars Ovesen
- Institute of Food Safety and Nutrition, Danish Food Administration, Søborg, Denmark.
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Phadnis R, Nemere I. Direct, rapid effects of 25-hydroxyvitamin D3 on isolated intestinal cells. J Cell Biochem 2003; 90:287-93. [PMID: 14505345 DOI: 10.1002/jcb.10639] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Scattered reports in the literature have suggested that the metabolite 25-hydroxyvitamin D(3) [25(OH)D(3)] has biological activity. In the present work, perfusion of isolated duodenal loops of normal chickens with 100 nM 25(OH)D(3) resulted in enhanced transport of (45)Ca within 2 min relative to the vehicle controls. We then tested the effect of a range of 25(OH)D(3) concentrations on (45)Ca handling by isolated intestinal cells in time course studies. Following a basal uptake period, cell suspensions from 7-week old chicks were treated either with 25, 100, or 300 nM 25(OH)D(3), or the vehicle ethanol (0.01%, final concentration). Both 25 and 100 nM 25(OH)D(3) resulted in a significant (P < 0.05) reduction in (45)Ca levels, relative to controls, between 1-10 min after treatment, while 300 nM 25(OH)D(3) resulted in a significant increase in (45)Ca levels, relative to controls, after 10 min of incubation. The effect of 100 nM 25(OH)D(3) (a physiological level) on cell calcium was abolished by the presence of 6.5 nM 24,25-dihydroxyvitamin D(3). In cell preparations from 14- or 28-week old birds 100nM 25(OH)D(3) had no effect, relative to vehicle controls. Incubation of cells with 2 microM BAY K8644, a calcium channel activator, stimulated (45)Ca uptake within 3 min relative to vehicle controls (P < 0.05), while addition of either 20 microM forskolin or 100 nM phorbol ester (stimulators of the PKA and PKC pathways, respectively) resulted in enhanced radionuclide levels after 10 min of incubation (P < 0.05, relative to corresponding controls). Finally, cells were treated with 100 nM 25(OH)D(3) or vehicle and samples taken at various times for analyses of protein kinase C and A activities. No effect of 25(OH)D(3) on protein kinase C activity was observed, while protein kinase A activity was stimulated to nearly 200% of controls at 1 min after 25(OH)D(3) addition (P < 0.05, relative to corresponding controls) and began declining at 3 min, returning to control levels 5 min after additions. We conclude that 25(OH)D(3) has a direct effect on calcium handling in enterocytes of young animals that may in part be mediated by the protein kinase A signal transduction pathway.
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Affiliation(s)
- Ruta Phadnis
- Department of Nutrition and Food Sciences and the Biotechnology Center, Utah State University, Logan, Utah 84322-8700, USA
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Larsson D, Nemere I, Sundell K. Putative basal lateral membrane receptors for 24,25-dihydroxyvitamin D(3) in carp and Atlantic cod enterocytes: characterization of binding and effects on intracellular calcium regulation. J Cell Biochem 2001; 83:171-86. [PMID: 11573235 DOI: 10.1002/jcb.1229] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The vitamin D metabolite, 24R,25-dihydroxyvitamin D(3) (24R,25(OH)(2)D(3)), was tested for its ability to specifically bind to basal lateral membranes isolated from intestinal epithelium of Atlantic cod (a seawater fish), carp (a freshwater fish), and chicken. Specific saturable binding was demonstrated in membranes from all three species. Membranes from Atlantic cod, carp, and chicken revealed K(d)'s of 7.3 +/- 0.9, 12.5 +/- 0.9 and 7.8 +/- 0.1 nM, and a B(max) for each species estimated to 57.9 +/- 2.9, 195.1 +/- 8.4 and 175 +/- 0.8 fmol/mg protein, respectively. Scatchard analyses indicated a convex curvature and Hill analyses revealed apparent Hill coefficients of 1.84 +/- 0.28, 1.80 +/- 0.29, and 1.78 +/- 0.27 for Atlantic cod, carp and chicken, suggesting a positive cooperative binding in all three species. Basal lateral membranes from Atlantic cod and carp were used to further characterize the binding moiety. In competition studies, basal lateral membranes from Atlantic cod or carp did not discriminate between 24R,25(OH)(2)D(3) and the 24S,25(OH)(2)D(3) isomer, whereas, 1,25(OH)(2)D(3) and 25(OH)D(3), were less effective in competing with [(3)H]24R,25(OH)(2)D(3) for binding to basal lateral membranes in Atlantic cod and carp. In both the Atlantic cod and carp enterocyte basal lateral membranes, the binding activity could be extracted equally well with high salt as with detergent, indicating a peripheral membrane protein rather than an integral membrane binding protein. Finally, isolated Atlantic cod and carp enterocytes were chosen for analyses of signal transduction events mediated by the putative receptor. In both species, 24R,25(OH)(2)D(3) but not 24S,25(OH)(2)D(3), suppressed Ca(2+)-uptake by enterocytes in a dose-dependent manner. Enterocytes from Atlantic cod and carp, acclimated to Ca(2+)-free media, responded by an intracellular Ca(2+)-release within seconds after addition of 24R,25(OH)(2)D(3) or 24S,25(OH)(2)D(3). The effects on intracellular Ca(2+)-release were dose-dependent for both metabolites. 24S,25(OH)(2)D(3) was effective at lower concentrations and triggered a higher response compared to 24R,25(OH)(2)D(3). These results suggest that the binding molecule(s) for 24R,25(OH)(2)D(3) and 24S,25(OH)(2)D(3) is/are capable of acting as a receptor, mediating rapid, non-genomic responses in intestinal cells.
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Affiliation(s)
- D Larsson
- Department of Zoology, Fish Endocrinology Laboratory, Göteborg University, Göteborg, Sweden.
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Bertolo RF, Bettger WJ, Atkinson SA. Calcium competes with zinc for a channel mechanism on the brush border membrane of piglet intestine. J Nutr Biochem 2001; 12:66-72. [PMID: 11182548 DOI: 10.1016/s0955-2863(00)00125-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Interactions between Ca(+2) and Zn(+2) at the intestinal brush border membrane occur via unclear mechanisms. We hypothesized that Zn(+2) and Ca(+2) are transported across the brush border membrane via a multidivalent metal channel. Using brush border membrane vesicles (BBMV) prepared from intestines of 8 sow-fed piglets, we sought to determine whether Ca(+2) competes with Zn(+2) for uptake. Extravesicular Zn(+2) was removed with ethylenediamine-tetraacetic acid. Time curves of Zn(+2) and Ca(+2) uptake by BBMV were conducted with increasing concentrations of Ca(+2) and Zn(+2), respectively. Saturation curves compared kinetic parameters of Zn(+2) uptake with and without Ca(+2). In addition, Zn(+2) uptake was measured in the presence of various classical Ca(+2) channel modulators. Over 20 min, a 0.4x concentration of Zn(+2) lowered Ca(+2) uptake by vesicles, whereas a 30x concentration of Ca(+2) was necessary to lower Zn(+2) uptake. These data suggest that Ca(+2) has lower affinity than Zn(+2) for a brush border membrane transport protein. Kinetic parameters showed higher K(m) values with 4 or 15 mM Ca(+2) but unchanged J(max), suggesting competitive inhibition. The Ca(+2) channel blocking agents, La(+3), Ba(+2), verapamil, and diltiazem, inhibited Zn(+2) uptake, whereas calcitriol, trans 1,2 cyclohexanediol, cis/trans 1,3 cyclohexanediol, and the L-type Ca(+2) channel agonist, Bay K8644, induced Zn(+2) uptake. These data were consistent with competition for a common transport mechanism on the brush border membrane, possibly a novel multimetal channel. Copyright 2001 Elsevier Science Inc.
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Affiliation(s)
- R F.P. Bertolo
- Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
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Nemere I. 24,25-dihydroxyvitamin D3 suppresses the rapid actions of 1, 25-dihydroxyvitamin D3 and parathyroid hormone on calcium transport in chick intestine. J Bone Miner Res 1999; 14:1543-9. [PMID: 10469282 DOI: 10.1359/jbmr.1999.14.9.1543] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Studies were undertaken to determine whether 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) modulates the rapid effects of 1, 25-dihydroxyvitamin D3 (1,25(OH)2D3) and parathyroid hormone (PTH) on calcium transport in the perfused chick intestine. Perfusion with control media resulted in a transport ratio (treated/average basal) of 1.07 +/- 0.06 at t = 40 minutes, while perfusion with 65, 130, 300, or 650 pM 1,25(OH)2D3 yielded ratios of 1.92 +/- 0.23, 2.6 +/- 0.4, 2.8 +/- 0.08, and 3.34 +/- 0.37, respectively. Simultaneous perfusion with each of these doses and 6.5 nM 24,25(OH)2D3 reduced treated/average basal ratios to approximately 1.4 after 40 minutes of perfusion. Vascular perfusion with 65 pM bovine PTH [bPTH(1-34)] stimulated intestinal calcium transport ratios to 3.0 +/- 0.5 after 40 minutes, while the inclusion of 6.5 nM 24,25(OH)2D3 reduced ratios at this time point to 0.56 +/- 0.19. To investigate the effect of these agents on signal transduction, isolated intestinal cells were monitored for intracellular calcium changes using the indicator dye fura-2. After establishing a stable baseline, addition of 130 pM 1,25(OH)2D3 induced rapid calcium oscillations. Intestinal cells exposed to 6.5 nM 24,25(OH)2D3 also exhibited rapid oscillations in fluorescence, which were not further altered by subsequent addition of 1,25(OH)2D3. Incubation of isolated cells with 130 pM 1,25(OH)2D3 was found to increase protein kinase C (PKC) activity within 5 minutes, and protein kinase A (PKA) activity within 7 minutes. Exposure of cells to 65 pM bPTH(1-34) had minimal effect on PKC activity, but resulted in pronounced increases in PKA activity. Stimulation of protein kinases by either secosteroid or peptide hormone was inhibited in the presence of 6.5 nM 24,25(OH)2D3. It is concluded that 24,25(OH)2D3 may exert endocrine actions on intestine.
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Affiliation(s)
- I Nemere
- Department of Nutrition and Food Science, and the Biotechnology Center, Utah State University, Logan, Utah 84322-8700, USA
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Kabat MM, Burger W, Guggino S, Hennessy B, Iacobelli JA, Takeuchi K, Uskoković MR. Total synthesis of 25-hydroxy-16,23E-diene vitamin D3 and 1 alpha,25-dihydroxy-16,23E-diene vitamin D3: separation of genomic and nongenomic vitamin D activities. Bioorg Med Chem 1998; 6:2051-9. [PMID: 9881096 DOI: 10.1016/s0968-0896(98)00164-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Separation of genomic and nongenomic vitamin D activities was achieved by structural modification of 1,25-dihydroxy vitamin D3 by introduction of 16 and 23E double bonds. The modified compound 3, lacking a 1 alpha-hydroxy group, exhibits only nongenomic activity. Its 1 alpha-hydroxy relative 4 expresses fully both genomic and non-genomic activities. A total synthesis of analogues 3 and 4 is described.
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Affiliation(s)
- M M Kabat
- Roche Research Center, Hoffmann-La Roche Inc., Nutley, NJ 07110, USA
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Nemere I, Farach-Carson MC. Membrane receptors for steroid hormones: a case for specific cell surface binding sites for vitamin D metabolites and estrogens. Biochem Biophys Res Commun 1998; 248:443-9. [PMID: 9703943 DOI: 10.1006/bbrc.1998.8492] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Steroid hormones, including vitamin D metabolites and estrogens, activate target cells through specific receptors that discriminate among ligands based upon recognition of distinct structural features. For both classes of ligands, cell surface and nuclear receptors co-exist in many target cells. Upon ligand binding, these receptors generate both rapid and long lasting responses. While the structure of the nuclear receptors and their function as transcriptional activators of specific target genes is generally understood, the identity of the membrane receptors remains elusive. Using pharmacological, functional and biochemical approaches, new insights are being gained into nature of the cell surface receptors for both vitamin D metabolites and estrogens.
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Affiliation(s)
- I Nemere
- Department of Nutrition and Food Sciences, Utah State University, Logan 84322, USA
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Takeuchi K, Guggino SE. 24R,25-(OH)2 vitamin D3 inhibits 1alpha,25-(OH)2 vitamin D3 and testosterone potentiation of calcium channels in osteosarcoma cells. J Biol Chem 1996; 271:33335-43. [PMID: 8969193 DOI: 10.1074/jbc.271.52.33335] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Calcium influx via L-type calcium channels in osteoblast cells causes a rapid (in seconds) elevation in intracellular calcium initiated by plasma membrane receptors for 1alpha, 25-dihydroxyvitamin D3 (1alpha,25-D3). 24R,25-Dihydroxyvitamin D3 (24,25-D3) alone, in concentrations up to 200 nM, does not cause potentiation of calcium currents in osteoblasts, but it does inhibit the current potentiation by 1alpha,25-D3. To determine how various steroids interact in their potentiation of calcium channels, the action of vitamin D3 analogues and testosterone with calcium channels in the rat osteoblast-like cell line ROS 17/2.8 was investigated. Bath additions of both 1alpha,25-D3 and testosterone at doses below K1/2 (the dose causing 50% left shift in the current-voltage relationship) are additive in their ability to potentiate calcium channels. When 1alpha,25-D3 and testosterone are added together at concentrations that would cause a maximal shift in the current-voltage relationship by each agent alone (Vmax), the effect of these steroids is not additive. Taken together these data suggest one population of calcium channels is activated by 1alpha, 25-D3 or testosterone. The shift in the current-voltage relationship caused by 1alpha,25-D3 is reduced by 1beta,25-dihydroxyvitamin D3 (1beta,25-D3), an agent which is thought to act specifically on the plasma membrane receptor for 1alpha,25-D3, but the potentiation caused by testosterone is not blocked by 1beta,25-D3. However, 24, 25-D3 inhibits the left shift in the peak current-voltage relationship mediated by either 1alpha,25-D3 and testosterone. This result implies that 1) 1beta,25-D3 directly displaces 1alpha,25-D3 but not testosterone from its plasma membrane receptor, and 2) the rapid (in seconds) stimulatory effects of 1alpha,25-D3 and testosterone on calcium channels are mediated by separate plasma membrane receptors for testosterone and 1alpha,25-D3, which are blocked by another receptor for 24,25-D3. The interaction of these three receptors with L-type calcium channels is pertussis toxin-sensitive.
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Affiliation(s)
- K Takeuchi
- Department of Medicine, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA
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Meszaros JG, Karin NJ, Akanbi K, Farach-Carson MC. Down-regulation of L-type Ca2+ channel transcript levels by 1,25-dihyroxyvitamin D3. Osteoblastic cells express L-type alpha1C Ca2+ channel isoforms. J Biol Chem 1996; 271:32981-5. [PMID: 8955142 DOI: 10.1074/jbc.271.51.32981] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Osteoblast Ca2+ channels play a fundamental role in controlling intracellular and systemic Ca2+ homeostasis. A reverse transcription-polymerase chain reaction strategy was used to determine the molecular identity of voltage-sensitive calcium channels present in ROS 17/2.8 osteosarcoma cells. The amino acid sequences encoded by the two resultant PCR products matched the alpha1C-a and the alpha1C-d isoforms. The ability of 1, 25-dihydroxyvitamin D3 (1,25(OH)2D3) and structural analogs to modulate expression of voltage-sensitive calcium channel mRNA transcripts was then investigated. ROS 17/2.8 cells were cultured for 48 h in the presence of either 1,25(OH)2D3,1,24-dihydroxy-22-ene-24-cyclopropyl D3 (analog BT) or 25-hydroxy-16-ene-23-yne-D3 (analog AT), and the levels of mRNA encoding alpha1C were quantitated using a competitive reverse transcription-polymerase chain reaction assay. We found that 1, 25(OH)2D3 and analog BT reduced steady state levels of alpha1C mRNA. Conversely, the Ca2+-mobilizing analog AT did not alter steady state levels of voltage-sensitive calcium channel mRNA. Since analog BT, but not analog AT, binds and transcriptionally activates the nuclear receptor for 1,25(OH)2D3, these findings suggest that the down-regulation of voltage-sensitive calcium channel mRNA levels may involve the nuclear receptor.
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Affiliation(s)
- J G Meszaros
- Department of Basic Sciences, University of Texas Dental Branch, Houston, Texas 77030, USA.
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Ebihara K, Masuhiro Y, Kitamoto T, Suzawa M, Uematsu Y, Yoshizawa T, Ono T, Harada H, Matsuda K, Hasegawa T, Masushige S, Kato S. Intron retention generates a novel isoform of the murine vitamin D receptor that acts in a dominant negative way on the vitamin D signaling pathway. Mol Cell Biol 1996; 16:3393-400. [PMID: 8668154 PMCID: PMC231333 DOI: 10.1128/mcb.16.7.3393] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We identified and characterized a novel rat vitamin D receptor isoform (rVDR1), which retains intron 8 of the canonical VDR (rVDR0) during alternative splicing. In this isoform protein directed by the stop codon in this newly identified exon, a part of the ligand binding domain (86 amino acids) is truncated at the C-terminal end but contains 19 extra amino acids. The rVDR1 transcript was expressed at a level 1/15 to 1/20 of that of rVDR0 in the kidney and intestine in adult rats but not in embryos. The recombinant rVDR1 protein showed no ligand binding activity. Homo- and heterodimers of the recombinant rVDR0 and rVDR1 proteins bound to a consensus vitamin D response element (VDRE) but not to consensus response elements for thyroid hormone and retinoic acid. However, unlike rVDR0, rVDR1 did not form a heterodimeric complex with RXR on the VDRE. A transient expression assay showed that this isoform acted as a dominant negative receptor against rVDR0 transactivation. Interestingly, the dominant negative activities of rVDR1 differed among VDREs. Thus, the present study indicates that this new VDR isoform negatively modulates the vitamin D signaling pathway, through a particular set of target genes.
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Affiliation(s)
- K Ebihara
- Department of Agricultural Chemistry, Tokyo University of Agriculture, Setagayaku, Japan
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Identification of a specific binding protein for 1 alpha,25-dihydroxyvitamin D3 in basal-lateral membranes of chick intestinal epithelium and relationship to transcaltachia. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)31579-x] [Citation(s) in RCA: 219] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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16
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Norman A, Bouillon R, Farach-Carson M, Bishop J, Zhou L, Nemere I, Zhao J, Muralidharan K, Okamura W. Demonstration that 1 beta,25-dihydroxyvitamin D3 is an antagonist of the nongenomic but not genomic biological responses and biological profile of the three A-ring diastereomers of 1 alpha,25-dihydroxyvitamin D3. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(20)80689-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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17
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Schwartz Z, Langston GG, Swain LD, Boyan BD. Inhibition of 1,25-(OH)2D3- and 24,25-(OH)2D3-dependent stimulation of alkaline phosphatase activity by A23187 suggests a role for calcium in the mechanism of vitamin D regulation of chondrocyte cultures. J Bone Miner Res 1991; 6:709-18. [PMID: 1659121 DOI: 10.1002/jbmr.5650060708] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This study used the ionophore, A23187, to examine the hypothesis that the regulation of alkaline phosphatase and phospholipase A2 activity by vitamin D3 metabolites in cartilage cells is mediated by changes in calcium influx. Confluent, fourth-passage cultures of growth zone and resting zone chondrocytes from the costochondral cartilage of 125 g rats were incubated with 0.01-10 microM A23187. Specific activities of alkaline phosphatase and phospholipase A2 were measured in the cell layer and in isolated plasma membranes and matrix vesicles. There was an inhibition of alkaline phosphatase specific activity at 0.1 microM A23187 in resting zone cells and at 0.1 and 1 microM in growth zone chondrocytes. At these concentrations of ionophore, the 45Ca content of the chondrocytes was shown to increase. Both the plasma membrane and matrix vesicle enzyme activities were inhibited. There was no effect of ionophore on matrix vesicle or plasma membrane phospholipase A2 in either cell type. In contrast, alkaline phosphatase activity is stimulated when growth zone chondrocytes are incubated with 1,25-(OH)2D3 and in resting zone cells incubated with 24,25-(OH)2D3. Phospholipase A2 activity is differentially affected depending on the metabolite used and the cell examined. Addition of ionophore to cultures preincubated with 1,25-(OH)2D3 or 24,25-(OH)2D3 blocked the stimulation of alkaline phosphatase by the vitamin D3 metabolites in a dose-dependent manner. The effects of ionophore were not due to a direct effect on the membrane enzymes since enzyme activity is isolated membranes incubated with A23187 in vitro was unaffected. These results suggest a role for calcium in the action of vitamin D metabolites on chondrocyte membrane enzyme activity but indicate that mechanisms other than merely Ca2+ influx per se are involved.
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Affiliation(s)
- Z Schwartz
- Department of Periodontics, Hebrew University, Hadassah School of Dental Medicine, Jerusalem, Israel
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Langston GG, Swain LD, Schwartz Z, Del Toro F, Gomez R, Boyan BD. Effect of 1,25(OH)2D3 and 24,25(OH)2D3 on calcium ion fluxes in costochondral chondrocyte cultures. Calcif Tissue Int 1990; 47:230-6. [PMID: 2242495 DOI: 10.1007/bf02555924] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Vitamin D3 metabolites have been shown to affect proliferation, differentiation, and maturation of cartilage cells. Previous studies have shown that growth zone chondrocytes respond primarily to 1,25(OH)2D3 whereas resting zone chondrocytes respond primarily to 24,25(OH)2D3. To examine the role of calcium in the mechanism of hormone action, this study examined the effects of the Ca ionophore A23187, 1,25(OH)2D3, and 24,25(OH)2D3 on Ca influx and efflux in growth zone chondrocytes and resting zone chondrocytes derived from the costochondral junction of 125 g rats. Influx was measured as incorporation of 45Ca. Efflux was measured as release of 45Ca from prelabeled cultures into fresh media. The pattern of 45Ca influx in unstimulated (control) cells over the incubation period was different in the two chondrocyte populations, whereas the pattern of efflux was comparable. A23187 induced a rapid influx of 45Ca in both types of chondrocytes which peaked by 3 minutes and was over by 6 minutes. Influx was greatest in the growth zone chondrocytes. Addition of 10(-8)-10(-9) M 1,25(OH)2D3 to growth zone chondrocyte cultures results in a dose-dependent increase in 45Ca influx after 15 minutes. Efflux was stimulated by these concentrations of hormone throughout the incubation period. Addition of 10(-6)-10(-7) M 24,25(OH)2D3 to resting zone chondrocytes resulted in an inhibition in ion efflux between 1 and 6 minutes, with no effect on influx during this period. Efflux returned to control values between 6 and 15 minutes. 45Ca influx was inhibited by these concentrations of hormone from 15 to 30 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- G G Langston
- Department of Periodontics, Wilford Hall USAF Medical Center, Lackland Air Force Base, Texas
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Lieberherr M, Grosse B, Duchambon P, Drüeke T. A Functional Cell Surface Type Receptor Is Required for the Early Action of 1,25-Dihydroxyvitamin D3 on the Phosphoinositide Metabolism in Rat Enterocytes. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)47076-2] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Cancela L, Nemere I, Norman AW. 1 alpha,25(OH)2 vitamin D3: a steroid hormone capable of producing pleiotropic receptor-mediated biological responses by both genomic and nongenomic mechanisms. JOURNAL OF STEROID BIOCHEMISTRY 1988; 30:33-9. [PMID: 2838693 DOI: 10.1016/0022-4731(88)90073-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Vitamin D3 is now considered a pro-hormone and its biological activities are in a great majority due to its hormonally active derivative 1 alpha,25-dihydroxyvitamin D3. The actions of vitamin D3 have been extensively studied both in vivo and in vitro using different animal models as well as a diversity of cell types including intestinal epithelial cells, kidney cells, lymphocytes, macrophages and a number of malignant cell lines. Results thus obtained have considerably extended the number of target tissues for this vitamin and hormone far beyond its classical target organs, parathyroid gland, kidney, intestine and bone. Studies performed at the cellular, subcellular and molecular levels have led to the establishment of new concepts on the mode of action of vitamin D3 which is not believed to act through receptor-mediated genomic and nongenomic events leading to the expression of the full biological response.
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Affiliation(s)
- L Cancela
- Division of Biomedical Sciences, University of California, Riverside 92521-0121
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