Metabolism of 25-hydroxyvitamin D3 to 24,25-dihydroxyvitamin D3 and its sensitivity to ketoconazole in 1α,25-dihydroxyvitamin D3-differentiated HL60 cells

1989 ◽  
Vol 3 (3) ◽  
pp. 199-205 ◽  
Author(s):  
M. E. Hayes ◽  
D. Bayley ◽  
E. B. Mawer
Keyword(s):  
High Performance ◽  
Cell Number ◽  
Dependent Manner ◽  
Macrophage Phenotype ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
25 Hydroxyvitamin D ◽  
Dose Dependent

ABSTRACT Regulation of the metabolism of [3H]25-hydroxyvitamin D3 ([3H]25-(OH)D3) in vitro to material with the characteristics of [3H]24,25-dihydroxyvitamin D3 ([3H]24,25-(OH)2D3) has been studied in the human promyelocytic cell line HL60. Synthesis of 24,25-(OH)2D3 was induced in a dose-dependent manner in cells pretreated with 0·1–100 nm 1α,25-dihydroxyvitamin D3 (1α,25-(OH)2D3) for 4 days. This treatment also inhibited cell proliferation and stimulated differentiation to a macrophage phenotype that was characterized by staining for non-specific esterase (NSE) activity. The ability to synthesize [3H]24,25-(OH)2D3 from [3H]25-(OH)D3 and the expression of NSE activity both responded to changes in concentration of 1α,25-(OH)2D3 in the culture medium in a parallel manner. Synthesis of [3H]24,25-(OH)2D3 was linear when the incubation time was between 1 and 8 h and the cell number between 1 and 12×106 cells/incubation. The optimum substrate concentration for its synthesis was 125 nm, giving an apparent Michaelis constant of 360 nm. The identity of the [3H]24,25-(OH)2D3 synthesized by these cells was confirmed by co-chromatography with authentic 24,25-(OH)2D3 on normal-phase and reverse-phase high-performance liquid chromatography systems and by its reaction to sodium-m-periodate. Cells that had been exposed to 100 nm 1α,25-(OH)2D3 for 4 days synthesized 2·17±0·07 (s.e.m.) pmol 24,25-(OH)2D3/106 cells per h. This synthesis was inhibited in a dose-dependent manner over a concentration range of 0·01–1 μm by the drug ketoconazole, an antimycotic imidazole which is a known inhibitor of certain cytochrome P-450 enzyme systems, suggesting that the HL60 25-(OH)D3-24-hydroxylase is also a P-450-dependent enzyme system.

Role of 25-hydroxyvitamin D3 dose in determining rat 1,25-dihydroxyvitamin D3 production

1990 ◽  
Vol 258 (5) ◽  
pp. E780-E789 ◽  
Author(s):  
R. Vieth ◽  
K. McCarten ◽  
K. H. Norwich
Keyword(s):  
Specific Activity ◽  
Metabolic Clearance ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
25 Hydroxyvitamin D ◽  
Dose Dependent

To understand the relationships among 1) the dose of 25-hydroxyvitamin D [25(OH)D] in vivo, 2) the activity of 1-hydroxylase in renal mitochondria, and 3) the production of 1,25-dihydroxyvitamin D [1,25(OH)2D] in vivo, we gave rats different chronic or acute doses of 25-hydroxyvitamin D3 [25(OH)D3]. We followed the metabolism of intracardially administered [25-hydroxy-26,27-methyl-3H]cholecalciferol [25(OH)[3H]D3] for 24 h before killing by measuring extracts of serum by chromatography. Specific activity of 1-hydroxylase in kidney was measured at death. In rats given 0-2,000 pmol 25(OH)D3 chronically by mouth, there was a dose-dependent decline in the percent of serum radioactivity made up of 1,25-dihydroxy-[26,27-methyl-3H]cholecalciferol [1,25(OH)2[3H]D3] as well as a decline in mitochondrial 1-hydroxylase, and these correlated significantly (r = 0.83, P less than 0.001). Serum %1,25(OH)2[3H]D3 in this experiment ranged from 0.8 to 42%. A small part of this range could be accounted for by a faster metabolic clearance rate (MCR) of 1,25(OH)2D3 from rats supplemented with 25(OH)D3 (MCR, 2.12 +/- 0.10 ml/min) compared with rats restricted in vitamin D (MCR, 0.94 +/- 0.06 ml/min, P less than 0.001). The activity of 1-hydroxylase was by far the major factor determining serum %1,25(OH)2[3H]D3. When different acute doses of 25(OH)D3 were given to rats with identical specific activities of 1-hydroxylase, the resulting 1,25(OH)2D3 concentrations in serum correlated with the 25(OH)D3 dose (r = 0.99, P less than 0.001). We conclude that the behavior of 1-hydroxylase in vivo is analogous to the classic behavior in vitro of an enzyme functioning below its Michaelis constant (Km). The amount of 1-hydroxylase present in renal mitochondria determines the fraction (not simply the quantity) of 25(OH)D metabolized to 1,25(OH)2D3 in vivo.

Effect of 1,25-dihydroxyvitamin D3 on rat pituitary prolactin release

1987 ◽  
Vol 116 (4) ◽  
pp. 459-464 ◽  
Author(s):  
Kid Törnquist
Keyword(s):  
Pituitary Cells ◽  
Dihydroxyvitamin D3 ◽  
Enhancing Effect ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
Rat Pituitary ◽  
25 Hydroxyvitamin D ◽  
Pituitary Prolactin

Abstract. The effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on PRL secretion from rat pituitary in vivo and in vitro was investigated. Treating the rats for three days with 0.05 μg/kg per day had no effect on basal PRL secretion, whereas the TRH-induced PRL secretion was increased (P < 0.001). The enhancing effect of 1,25(OH)2D3 was blunted by verapamil. Incubating dispersed anterior pituitary cells with 10−8 mol/l 1,25(OH)2D3 induced a significant increase in PRL secretion after 96 h (364 ± 30 ng/well vs 481 ± 33 ng/well, P < 0.001; mean ± sem) compared with control cells. The TRH-induced PRL secretion was increased in cells incubated with 1,25(OH)2D3 for 144 h (0.766 ± 0.061 vs 1.024 ± 0.076 μg/well, P < 0.05; mean ± sem) compared with control cells. Neither 25-hydroxyvitamin D3 (25OH-D3) nor 24,25-dihydroxyvitamin D3 had any effects on the PRL secretion. However, when the cells were incubated with both 10−8 mol/l 1,25(OH)2D3 and 10−6 mol/l 25OHD3, the enhancing effect of 1,25(OH)2D3 on the basal PRL secretion was blunted. The results suggest that 1,25(OH)2D3 possibly affects the regulation of PRL release from the rat pituitary and that this effect is specific for 1,25(OH)2D3.

Vitamin D metabolites regulate osteocalcin synthesis and proliferation of human bone cells in vitro

1985 ◽  
Vol 105 (3) ◽  
pp. 391-396 ◽  
Author(s):  
H. Skjødt ◽  
J. A. Gallagher ◽  
J. N. Beresford ◽  
M. Couch ◽  
J. W. Poser ◽  
...  
Keyword(s):  
Vitamin D ◽  
Cell Proliferation ◽  
Bone Cells ◽  
Rank Order ◽  
Human Bone ◽  
Dependent Manner ◽  
Vitamin D Metabolites ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D

ABSTRACT The effects of six natural vitamin D metabolites of potential biological and therapeutic interest, 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), 25-hydroxyvitamin D3 (25-OH-D3), 24R,25-dihydroxyvitamin D3 (24R,25-(OH)2D3), 1,24R,25-trihydroxyvitamin D3 (1,24R,25-(OH)3D3), 25S,26-dihydroxyvitamin D3 (25S,26-(OH)2D3) and 1,25S,26-trihydroxyvitamin D3 (1,25S,26-(OH)3D3) on cell replication and expression of the osteoblastic phenotype in terms of osteocalcin production were examined in cultured human bone cells. At a dose of 5 × 10−12 mol/l, 1,25-(OH)2D3 stimulated cell proliferation, whereas at higher doses (5 × 10−9−5 × 10 −6 mol/l) cell growth was inhibited in a dose-dependent manner. The same pattern of effects was seen for the other metabolites in a rank order of potency: 1,25-(OH)2D3> 1,25S,26-(OH)3D3 = 1,24R,25-(OH)3D3>25S,26-(OH)2D3 = 24R,25-(OH)2D3 = 25-OH-D3. Synthesis of osteocalcin was induced by 1,25-(OH)2D3 in doses similar to those required to inhibit cell proliferation. Biphasic responses were observed for some of the metabolites in terms of osteocalcin synthesis, inhibitory effects becoming apparent at 5 × 10−6 mol/l. The cells did not secrete osteocalcin spontaneously. These results indicate that vitamin D metabolites may regulate growth and expression of differentiated functions of normal human osteoblasts. J. Endocr. (1985) 105, 391–396

1α,25-dihydroxyvitamin D3 corrects osteomalacia in hypoparathyroidism and pseudohypoparathyroidism

1983 ◽  
Vol 103 (2) ◽  
pp. 241-247 ◽  
Author(s):  
Sol Epstein ◽  
Pierre J. Meunier ◽  
Phillip W. Lambert ◽  
Paula H. Stern ◽  
Norman H. Bell
Keyword(s):  
Serum Calcium ◽  
Inorganic Phosphate ◽  
Binding Assay ◽  
Bone Biopsy ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
Before And After ◽  
25 Hydroxyvitamin D ◽  
Serum Inorganic Phosphate

Abstract. Deficiency of circulating 1α,25-dihydroxyvitamin D (1α,25(OH)2D) regularly occurs in hypoparathyroidism (HP) and pseudohypoparathyroidism (PHP). Osteomalacia is occasionally found in the two diseases. Two patients, one with HP and the other with PHP, both with symptomatic and biopsy-proven osteomalacia, were studied before and after treatment with 1α,25(OH)2D3. Laboratory values before treatment were as follows: serum immunoreactive parathyroid hormone was undetectable in the patient with HP and was elevated in the patient with PHP. Serum 25-hydroxyvitamin D, measured by binding assay, was 131.5 and 61.9 nmol/l (normal: 69.1 ± 15.9 nmol/l); serum 24,25-dihydroxyvitamin D, measured by binding assay, was 13.9 and 3.8 nmol/l (normal: 3.4 ± 1.4 nmol/l); serum 1α,25(OH)2D, measured by bioassay, was 28.6 and 29.0 pmol/l (normal: 77.3 ± 22.8 pmol/l) and, measured by receptor assay, was 36.2 and 41.0 pmol/l (normal: 71.8 ± 35.8 pmol/l) in the HP and PHP patients, respectively. Serum calcium was low and serum inorganic phosphate was high in both cases. Treatment with 1α,25(OH)2D3 (3–5 μg per day for 10–12 months) restored serum calcium and inorganic phosphate to normal, alleviated bone pain and healed the osteomalacia as shown on repeat bone biopsy. Our results provide further evidence that isolated deficiency of 1α,25(OH)2D may cause osteomalacia or rickets.

Systemic effects of 1,25-dihydroxyvitamin D3 on the pituitary-hypothalamic axis in rats

1987 ◽  
Vol 115 (2) ◽  
pp. 225-228 ◽  
Author(s):  
K. Törnquist ◽  
C. Lamberg-Allardt
Keyword(s):  
Hormone Secretion ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
25 Hydroxyvitamin D ◽  
Wet Weight ◽  
Indirect Action

Abstract. Treatment of rats with 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) 0.05 μg/kg per day for three days was without any effect on serum T3, T4 or TSH concentrations, whereas serum PRL increased (20.6 ± 3.8 to 76.2 ± 19.1 μg/l, mean ± sem, N = 7–8; P < 0.01). Increased hypothalamic TRH levels (24.3 ± 3.9 to 45.7 ± 7.8 pmol/g wet weight; P < 0.01) may indicate an effect of 1,25(OH)2D3 on hypothalamic TRH homeostasis. This effect could probably be due to an indirect action of 1,25(OH)2D3, mediated by the increased serum calcium (2.77 ± 0.02 to 3.16 ± 0.08 mmol/l, mean ± sem, N = 7–8; P < 0.001). This assumption was, however, not tested. Neither the pituitary TSH nor PRL was affected. The treatment decreased the serum concentration of 25-hydroxyvitamin D3 (23.0 ± 1.3 to 16.8 ± 2.0 nmol/l, mean ± sem, N = 5–7; P < 0.01) and of 24,25-dihydroxyvitamin D3 (3.2 ± 0.3 to 2.1 ± 0.1 nmol/l, mean ± sem, N = 3–5; P < 0.05). The results show that in this experimental design, 1,25(OH)2D3 has no effect on basal hormone secretion from the pituitary-thyroid axis, and that 1,25(OH)2D3 decreases the synthesis of the vitamin D3 metabolites studied.

Simultaneous determination of 25-hydroxy- and 1,25-dihydroxyvitamin D from a single sample by dual-cartridge extraction.

1984 ◽  
Vol 30 (1) ◽  
pp. 56-61 ◽  
Author(s):  
P C Kao ◽  
D W Heser
Keyword(s):  
High Performance ◽  
Vitamin D Metabolites ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D ◽  
Hydroxylated Metabolites ◽  
Silica Cartridge ◽  
25 Hydroxyvitamin D ◽  
The Mean

Abstract With this dual-cartridge system we extract 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)2D] from a single serum sample by using a nonpolar octadecylsilanol silica cartridge to adsorb the vitamin D metabolites and other nonpolar substances; the polar substances wash through the cartridge. The eluted material is then applied to a second alkylamine cartridge, which adsorbs the relatively polar hydroxylated metabolites; the less-polar substances are washed from the second cartridge. Elution from the second cartridge purifies and also separates 25(OH)D and 1,25(OH)2D with analytical recoveries near 90%. The monohydroxyl metabolites are determined by "high-performance" liquid chromatography (HPLC); the dihydroxyl metabolites are further purified by HPLC and determined by radioreceptor assay according to established procedures. Mean (+/- SD) winter normal values (34 subjects of both sexes; blood drawn in mid-April) were 18 +/- 5 micrograms/L for 25(OH)D and 25 +/- 7 ng/L for 1,25(OH)2D. In nine laboratory volunteers, the mean increase in the serum 25(OH)D3 value 5 h after ingestion of 50 micrograms of 25-hydroxycholecalciferol (Calderol) was 9 (SD 4) micrograms/L.

scholarly journals Association of Maternal Serum 25-Hydroxyvitamin D Concentrations with Risk of Gestational Anemia

2017 ◽  
Vol 43 (4) ◽  
pp. 1526-1532 ◽  
Author(s):  
Yingdi Yuan ◽  
Zhiyong Cai ◽  
YaoYao Dai ◽  
Qin Hong ◽  
Xingyun Wang ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Pregnant Women ◽  
Maternal Serum ◽  
Dependent Manner ◽  
Hydroxyvitamin D ◽  
Increased Risk ◽  
25 Hydroxyvitamin D ◽  
Nested Case Control ◽  
Dose Dependent ◽  
Prevalence Of Anemia

Background/Aims: Vitamin D deficiency has been shown to be associated with a greater prevalence of anemia in various healthy and diseased populations by a great deal of observational studies. However, less work has been done to explore this association in pregnant women. The aim of this study was to evaluate the association between maternal serum 25-hydroxyvitamin D [25(OH)D] concentrations and risk of gestational anemia in a large, nested case-control study. Methods: The serum 25(OH)D concentrations was measured by enzyme immunoassay in 775 pregnant women affected with anemia and 1550 controls. Logistic regression analysis was conducted to assess the association of 25(OH)D concentrations with risk of gestational anemia. Results: We found the 25(OH)D concentrations was significantly lower in women affected with anemia than in controls. Logistic regression analyses showed that women with 25(OH)D concentrations < 25.0 nmol/L, from 25.0 to 37.4 nmol/L and from 37.5 to 49.9 nmol/L all had increased risk of anemia when compared with women with concentrations from 50.0 to 74.9 nmol/L. And the risk of anemia was significantly increased with the decreasing concentrations of the serum 25(OH)D in a dose-dependent manner (P for trend = 0.012). For women with concentrations < 50.0 nmol/L, they had an 80% increase in anemia risk (95% CI = 1.45-2.25) after adjustment for confounders. We also observed a nonlinear relationship between the serum 25(OH)D and anemia, with a threshold for 25(OH)D of 50.0 nmol/L existed for anemia. Conclusion: Maternal serum 25(OH)D < 50.0 nmol/L may be a risk factor for gestational anemia, and it should be monitored for the high-risk pregnant women.

Metabolism of 25-hydroxyvitamin D in copper-laden rat: a model of Wilson's disease

1988 ◽  
Vol 254 (2) ◽  
pp. E150-E154
Author(s):  
T. O. Carpenter ◽  
M. L. Pendrak ◽  
C. S. Anast
Keyword(s):  
Vitamin D ◽  
Wilson’S Disease ◽  
Wilson's Disease ◽  
Vitamin D Metabolism ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
Hepatic Copper ◽  
25 Hydroxyvitamin D ◽  
Potential Factor

Wilson's disease results in excess tissue accumulation of copper and is often complicated by skeletal and mineral abnormalities. We investigated vitamin D metabolism in rats fed a copper-laden diet rendering hepatic copper content comparable with that found in Wilson's disease. Injection of 25-hydroxyvitamin D3 [25(OH)D3] resulted in reduced 1,25-dihydroxyvitamin D [1,25(OH)2D] levels in copper-intoxicated rats. In vitro 25(OH)D-1 alpha-hydroxylase activity was impaired in renal mitochondria from copper-intoxicated animals. Activity was also inhibited in mitochondria from controls when copper was added to incubation media. Impaired conversion of 25(OH)D to 1,25(OH)2D occurs in copper intoxication and suggests that altered vitamin D metabolism is a potential factor in the development of bone and mineral abnormalities in Wilson's disease.

15-HETE-substituted diglycerides selectively regulate PKC isotypes in human tracheal epithelial cells

1999 ◽  
Vol 277 (3) ◽  
pp. L457-L464 ◽  
Author(s):  
Stephen E. Alpert ◽  
Ronald W. Walenga ◽  
Atashi Mandal ◽  
Nicole Bourbon ◽  
Mark Kester
Keyword(s):  
High Performance ◽  
Neutral Lipids ◽  
Platelet Activating Factor ◽  
Dependent Manner ◽  
Western Blots ◽  
Tracheal Epithelial Cells ◽  
Tracheal Epithelial ◽  
Layer Chromatography ◽  
Dose Dependent

Human tracheal epithelial (TE) cells selectively incorporate their major lipoxygenase product, 15-hydroxyeicosatetraenoic acid (15-HETE), into the sn-2 position of phosphatidylinositol (PI) (S. E. Alpert and R. W. Walenga. Am. J. Respir. Cell Mol. Biol. 8: 273–281, 1993). Here we investigated whether 15-HETE-PI is a substrate for receptor-mediated generation of 15-HETE-substituted diglycerides (DGs) and whether these 15-HETE-DGs directly activate and/or alter conventional diacylglycerol-induced activation of protein kinase C (PKC) isotypes in these cells. Primary human TE monolayers incubated with 0.5 μM 15-[3H]-HETE or 15-[14C]HETE for 1–2 h were stimulated with 1 nM to 1 μM platelet-activating factor (PAF) for 30 s to 6 min, and the radiolabel in the medium, cellular phospholipids, and neutral lipids was assessed by high-performance liquid and thin-layer chromatography. PAF mobilized radiolabel from PI in a dose-dependent manner (22 ± 5% decrease after 1 μM PAF) without a concomitant release of free intra- or extracellular 15-HETE. 14C-labeled DGs were present in unstimulated TE monolayers incubated with 15-[14C]HETE, and the major 14C band, identified as sn-1,2-15-[14C]HETE-DG, increased transiently in response to PAF. Western blots of freshly isolated and cultured human TE cells revealed PKC isotypes α, βI, βII, δ, ε, and ζ. In vitro, cell-generated sn-1,2-15-[14C]HETE-DG selectively activated immunoprecipitated PKC-α and inhibited diacylglycerol-induced activation of PKC-α, -δ, -βI, and -βII. Our observations indicate that 15-HETE-DGs can modulate the activity of PKC isotypes in human TE cells and suggest an intracellular autocrine role for 15-HETE in human airway epithelia.

scholarly journals Cloning of Porcine 25-Hydroxyvitamin D3 1α-Hydroxylase and Its Regulation by cAMP in LLC-PK1 Cells

1999 ◽  
Vol 10 (5) ◽  
pp. 963-970
Author(s):  
TADASHI YOSHIDA ◽  
NORIKO YOSHIDA ◽  
AKIRA NAKAMURA ◽  
TOSHIAKI MONKAWA ◽  
MATSUHIKO HAYASHI ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Cytochrome P450 Enzyme ◽  
Pcr Cloning ◽  
Humoral Factors ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
Reverse Transcription Pcr ◽  
25 Hydroxyvitamin D ◽  
Renal Proximal Tubular Cells

Abstract. The 25-hydroxyvitamin D3 1α-hydroxylase, also referred to as CYP27B1, is a mitochondrial cytochrome P450 enzyme that catalyzes the biosynthesis of 1α, 25-dihydroxyvitamin D3 (1α,25(OH)2D3) from 25-hydroxyvitamin D3 in renal proximal tubular cells. Recently, human, mouse, and rat CYP27B1 cDNA have been cloned, however the gene regulation has not been fully elucidated. In the present study, porcine CYP27B1 cDNA was cloned, and the effects of cAMP and vitamin D3 on the regulation of CYP27B1 mRNA expression in LLC-PK1 cells were examined. PCR cloning revealed that porcine CYP27B1 cDNA consisted of 2316 bp, encoding a protein of 504 amino acids. The deduced amino acid sequence showed over 80% identity to the human, mouse, and rat enzyme. LLC-PK1 cells were incubated with humoral factors, and expression of CYP27B1 mRNA was measured by a quantitative reverse transcription-PCR. At the completion of 3-, 6-, 12-, and 24-h incubations, 500 μmol/L 8-bromo-cAMP had significantly increased CYP27B1 mRNA expression (260 to 340%). The adenylate cyclase activator forskolin at 50 μmol/L also had a stimulatory effect at 6 h (190%). Moreover, the protein kinase A inhibitor H-89 reduced the cAMP effect. On the other hand, 1α,25(OH)2D3 had no effect on CYP27B1 mRNA expression at 10 and 100 nmol/L, whereas expression of 25-hydroxyvitamin D3 24-hydroxylase (CYP24) mRNA was markedly increased by 1α,25(OH)2D3. These findings suggest that LLC-PK1 cells express CYP27B1 mRNA, and that cAMP is an upregulating factor of the CYP27B1 gene in vitro.

Sign in / Sign up

Export Citation Format

Share Document