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Hydroxyvitamin D3 (hydroxyvitamin + d3)

Distribution by Scientific Domains
Medical Sciences50%
Chemistry27%
Life Sciences16%

Terms modified by Hydroxyvitamin D3

  • hydroxyvitamin d3 level
    		•

    Selected Abstracts

    The course of some bone remodelling plasma metabolites in healthy horses and in horses offered a calcium-deficient diet

    JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 3-4 2003
    V. De Behr
    Summary An inquiry was carried out to assess the concentrations of plasma metabolites related to bone remodelling in 21 saddle horses of Warmblood breed aged 4,26 years, five draught horses of Ardennes breed aged 4,10 years, and 10 Ardennes foals aged 9,11 months. They were fed according to normal feeding practice in Belgium. The changes in some bone remodelling plasma metabolite concentrations were studied when an unbalanced diet was offered and later corrected for four Warmblood horses. Bone formation was evaluated by bone alkaline phosphatase (BALP), total alkaline phosphatase (TALP) and osteocalcin (bone gla-protein, OC). Bone resorption was assessed by hydroxyproline (HYP). Total calcium, ionized calcium, phosphorus (P) and 25-hydroxyvitamin D3 [25-(OH)D] concentrations were more or less constant. The comparison of four bone remodelling factors between the Ardennes and Warmblood horses showed higher concentrations in the Ardennes breed. Bone marker concentrations decreased according to age. The correction of the unbalanced Ca : P diet induced inconsistent effects at plasma level. The interpretation of the different bone parameters appeared to be difficult if not associated with other parameters such as a complete anamnesis and clinical examination of the animal in addition to dietary evaluation. Zusammenfassung Verlauf verschiedener Knochenmarker bei gesunden Pferden und bei Pferden, welche mit einer in Bezug auf Kalzium unausgewogenen Ration gefüttert wurden Eine Studie zur Erfassung der Konzentrationen von Knochenmarkern wurde bei 21 Warmblütern im Alter von 4 bis 26 Jahren, fünf Ardenner Kaltblütern im Alter von 4 bis 10 Jahren und 10 Ardenner Kaltblutfohlen im Alter von 9 bis 11 Monaten durchgeführt. Die Pferde wurden gemäss der normalen Fütterungpraxis in Belgien gefüttert. Der Verlauf der Knochenmarkerkonzentrationen wurde auch bei vier Pferden gemessen, die zunächst mit einer unausgewogenen Ration in Bezug auf Kalzium und dann mit einer korrigierenden Ration gefüttert wurden. Der Knochenaufbau wurde anhand der Aktivität der knochenspezifischen alkalischen Phosphatase (BALP), der totalen alkalischen Phosphatasen (TALP) und anhand des Osteocalcin (bone gla-proteine, OC) gemessen. Der Knochenabbau wurde anhand des Hydroxyprolins (HYP) gemessen. Die Konzentrationen des totalen Kalziums, ionisierten Kalziums, Phosphors (P), und 25-Hydroxyvitamin D3 [25(OH)D] waren unverändert. Beim Vergleich der vier gemessenen Knochenmakerkonzentrationen bei den Ardenner Kaltblütern mit den Warmblutpferden konnte gezeigt werden, dass die Kaltblüter deutlich höhere Konzentrationen hatten als die Warmblüter. Die Konzentrationen der Marker nahmen mit steigendem Alter der Pferde ab. Die Korrektur der unausgewogenen Ca:P Ration ergab nicht eindeutige Veränderungen der Plasmakonzentrationen der verschiedenen Marker. Die Interpretation der verschiedenen Knochenmarker erscheint schwierig, wenn nicht andere Parameter, wie eine komplette Anamnese und eine klinische Untersuchung, sowie eine Auswertung der Ration hinzugezogen werden. [source]

    Dual metabolic pathway of 25-hydroxyvitamin D3 catalyzed by human CYP24

    FEBS JOURNAL, Issue 20 2000
    Toshiyuki Sakaki
    Human 25-hydroxyvitamin D3 (25(OH)D3) 24-hydroxylase (CYP24) cDNA was expressed in Escherichia coli, and its enzymatic and spectral properties were revealed. The reconstituted system containing the membrane fraction prepared from recombinant E. coli cells, adrenodoxin and adrenodoxin reductase was examined for the metabolism of 25(OH)D3, 1,,25(OH)2D3 and their related compounds. Human CYP24 demonstrated a remarkable metabolism consisting of both C-23 and C-24 hydroxylation pathways towards both 25(OH)D3 and 1,,25(OH)2D3, whereas rat CYP24 showed almost no C-23 hydroxylation pathway [Sakaki, T. Sawada, N. Nonaka, Y. Ohyama, Y. & Inouye, K. (1999) Eur. J. Biochem. 262, 43,48]. HPLC analysis and mass spectrometric analysis revealed that human CYP24 catalyzed all the steps of the C-23 hydroxylation pathway from 25(OH)D3 via 23S,25(OH)2D3, 23S,25,26(OH)3D3 and 25(OH)D3 -26,23-lactol to 25(OH)D3 -26,23-lactone in addition to the C-24 hydroxylation pathway from 25(OH)D3 via 24R,25(OH)2D3, 24-oxo-25(OH)D3, 24-oxo-23S,25(OH)2D3 to 24,25,26,27-tetranor-23(OH)D3. On 1,,25(OH)2D3 metabolism, similar results were observed. These results strongly suggest that the single enzyme human CYP24 is greatly responsible for the metabolism of both 25(OH)D3 and 1,,25(OH)2D3. We also succeeded in the coexpression of CYP24, adrenodoxin and NADPH-adrenodoxin reductase in E. coli. Addition of 25(OH)D3 to the recombinant E. coli cell culture yielded most of the metabolites in both the C-23 and C-24 hydroxylation pathways. Thus, the E. coli expression system for human CYP24 appears quite useful in predicting the metabolism of vitamin D analogs used as drugs. [source]

    The course of some bone remodelling plasma metabolites in healthy horses and in horses offered a calcium-deficient diet

    JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 3-4 2003
    V. De Behr
    Summary An inquiry was carried out to assess the concentrations of plasma metabolites related to bone remodelling in 21 saddle horses of Warmblood breed aged 4,26 years, five draught horses of Ardennes breed aged 4,10 years, and 10 Ardennes foals aged 9,11 months. They were fed according to normal feeding practice in Belgium. The changes in some bone remodelling plasma metabolite concentrations were studied when an unbalanced diet was offered and later corrected for four Warmblood horses. Bone formation was evaluated by bone alkaline phosphatase (BALP), total alkaline phosphatase (TALP) and osteocalcin (bone gla-protein, OC). Bone resorption was assessed by hydroxyproline (HYP). Total calcium, ionized calcium, phosphorus (P) and 25-hydroxyvitamin D3 [25-(OH)D] concentrations were more or less constant. The comparison of four bone remodelling factors between the Ardennes and Warmblood horses showed higher concentrations in the Ardennes breed. Bone marker concentrations decreased according to age. The correction of the unbalanced Ca : P diet induced inconsistent effects at plasma level. The interpretation of the different bone parameters appeared to be difficult if not associated with other parameters such as a complete anamnesis and clinical examination of the animal in addition to dietary evaluation. Zusammenfassung Verlauf verschiedener Knochenmarker bei gesunden Pferden und bei Pferden, welche mit einer in Bezug auf Kalzium unausgewogenen Ration gefüttert wurden Eine Studie zur Erfassung der Konzentrationen von Knochenmarkern wurde bei 21 Warmblütern im Alter von 4 bis 26 Jahren, fünf Ardenner Kaltblütern im Alter von 4 bis 10 Jahren und 10 Ardenner Kaltblutfohlen im Alter von 9 bis 11 Monaten durchgeführt. Die Pferde wurden gemäss der normalen Fütterungpraxis in Belgien gefüttert. Der Verlauf der Knochenmarkerkonzentrationen wurde auch bei vier Pferden gemessen, die zunächst mit einer unausgewogenen Ration in Bezug auf Kalzium und dann mit einer korrigierenden Ration gefüttert wurden. Der Knochenaufbau wurde anhand der Aktivität der knochenspezifischen alkalischen Phosphatase (BALP), der totalen alkalischen Phosphatasen (TALP) und anhand des Osteocalcin (bone gla-proteine, OC) gemessen. Der Knochenabbau wurde anhand des Hydroxyprolins (HYP) gemessen. Die Konzentrationen des totalen Kalziums, ionisierten Kalziums, Phosphors (P), und 25-Hydroxyvitamin D3 [25(OH)D] waren unverändert. Beim Vergleich der vier gemessenen Knochenmakerkonzentrationen bei den Ardenner Kaltblütern mit den Warmblutpferden konnte gezeigt werden, dass die Kaltblüter deutlich höhere Konzentrationen hatten als die Warmblüter. Die Konzentrationen der Marker nahmen mit steigendem Alter der Pferde ab. Die Korrektur der unausgewogenen Ca:P Ration ergab nicht eindeutige Veränderungen der Plasmakonzentrationen der verschiedenen Marker. Die Interpretation der verschiedenen Knochenmarker erscheint schwierig, wenn nicht andere Parameter, wie eine komplette Anamnese und eine klinische Untersuchung, sowie eine Auswertung der Ration hinzugezogen werden. [source]

    Effects of vegetable feed ingredients on bone health in Atlantic salmon

    JOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2010
    P. G. Fjelldal
    Summary The aim of the present study was to examine if dietary inclusion of vegetable lipids (VL) and proteins (VP) influenced markers of bone health in Atlantic salmon. Triplicate groups were fed one of four different diets; 100% fish protein (FP) and fish lipids (FL) (FPFL), 80% VP and 35% VL (80VP35VL), 40% VP and 70% VL (40VP70VL), or 80% VP and 70% VL (80VP70VL) for 12 months on-growth in sea water. Fish were analyzed for vertebral bone mineralization (mineral content, as % of bone dry weight), vertebral deformities (radiology), vertebral bone mRNA expression of factors involved in mineralization (bone gla protein, bgp) and growth regulation (igf-I and growth hormone receptor), as well as plasma vitamin D metabolites. The fish grew from 0.35 to 4 kg during the experimental period. At the end of the experiment, significantly lower prevalence of fish with one or more deformed vertebrae was observed in the 80VP70VL group (11%) compared to the other groups (33,43%). There was a significant higher relative expression of igf -I mRNA in vertebral bone of fish fed the 80VP70VL diet compared to control fish (FPFL), while the other genes studied were unaffected. Elevated plasma 25-hydroxyvitamin D3 recorded in the marine feed group is discussed as a predictor for later development of bone deformities. In conclusion, the present study shows that high inclusion levels of vegetable lipids and proteins may have a positive effect on bone health in Atlantic salmon postsmolts. [source]

    Hypercalcemia and Overexpression of CYP27B1 in a Patient With Nephrogenic Systemic Fibrosis: Clinical Vignette and Literature Review,,

    JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2009
    Vivian Y Pao
    Abstract Nephrogenic systemic fibrosis (NSF) is a disease of thickened, hard, hyperpigmented skin lesions with or without systemic fibrosis occurring in patients with renal insufficiency and associated with the administration of gadolinium-containing contrast. The pathogenesis of this disease is unclear, and there is no definitive treatment. We describe a 71-yr-old patient with stable chronic lymphocytic leukemia (CLL), end-stage renal disease (ESRD), and NSF who presented with hypercalcemia in 2006. Before onset of renal insufficiency in 2002, serum calcium, phosphorus, and PTH levels were normal. In 2004, the patient began hemodialysis, and he was diagnosed with NSF in 2005, shortly after undergoing an MRI with gadolinium contrast administration. Over the next 6 mo, albumin-corrected serum total calcium levels rose from 9.9 to 13.1 mg/dl (normal range, 8.5,10.5 mg/dl) with normal serum phosphorus levels. On admission in September 2006, 1,25-dihydroxyvitamin D [1,25(OH)2D] levels were elevated at 130.7 pg/ml (normal range, 25.1,66.1 pg/ml). Biopsy of an NSF lesion showed increased 25-hydroxyvitamin D3,1-, hydroxylase (CYP27B1) immunostaining compared with the biopsy from a normal control. This is the first reported association of NSF with hypercalcemia caused by elevated 1,25(OH)2D levels. This metabolic disturbance should be sought in future cases to determine a connection between NSF, 1,25(OH)2D metabolism, and CYP27B1 activation in the skin, which may shed light on the pathogenesis of this unusual local and systemic fibrosing disorder. [source]

    CYP3A4 is a Human Microsomal Vitamin D 25-Hydroxylase,

    JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2004
    Ram P Gupta
    Abstract The human hepatic microsomal vitamin D 25-hydroxylase protein and gene have not been identified with certainty. Sixteen hepatic recombinant microsomal enzymes were screened for 25-hydroxylase activity; 11 had some 25-hydroxylase activity, but CYP3A4 had the highest activity. In characterized liver microsomes, 25-hydroxylase activity correlated significantly with CYP3A4 testosterone 6,-hydroxylase activity. Activity in pooled liver microsomes was inhibited by known inhibitors of CYP3A4 and by an antibody to CYP3A2. Thus, CYP3A4 is a hepatic microsomal vitamin D 25-hydroxylase. Introduction: Studies were performed to identify human microsomal vitamin D-25 hydroxylase. Materials and Methods: Sixteen major hepatic microsomal recombinant enzymes derived from cytochrome P450 cDNAs expressed in baculovirus-infected insect cells were screened for 25-hydroxylase activity with 1,-hydroxyvitamin D2 [1,(OH)D2], 1,-hydroxyvitamin D3 [1,(OH)D3], vitamin D2, and vitamin D3 as substrates. Activity was correlated with known biological activities of enzymes in a panel of 12 characterized human liver microsomes. The effects of known inhibitors and specific antibodies on activity also were determined. Results: CYP3A4, the most abundant cytochrome P450 enzyme in human liver and intestine, had 7-fold greater activity than that of any of the other enzymes with 1,(OH)D2 as substrate. CYP3A4 25-hydroxylase activity was four times higher with 1,(OH)D2 than with 1,(OH)D3 as substrate, was much less with vitamin D2, and was not detected with vitamin D3. 1,(OH)D2 was the substrate in subsequent experiments. In a panel of characterized human liver microsomes, 25-hydroxylase activity correlated with CYP3A4 testosterone 6,-hydroxylase activity (r = 0.93, p < 0.001) and CYP2C91 diclofenac 4,-hydroxylase activity (r = 0.65, p < 0.05), but not with activity of any of the other enzymes. Activity in recombinant CYP3A4 and pooled liver microsomes was dose-dependently inhibited by ketoconazole, troleandomycin, isoniazid, and ,-naphthoflavone, known inhibitors of CYP3A4. Activity in pooled liver microsomes was inhibited by antibodies to CYP3A2 that are known to inhibit CYP3A4 activity. Conclusion: CYP3A4 is a vitamin D 25-hydroxylase for vitamin D2 in human hepatic microsomes and hydroxylates both 1,(OH)D2 and 1,(OH)D3. [source]

    Dissociation of growth arrest and CYP24 induction by VDR ligands in mammary tumor cells

    JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2007
    Meggan E. Valrance
    Abstract Murine mammary tumor cells with differential vitamin D receptor (VDR) expression were used to study the mechanisms of growth inhibition by vitamin D steroids. In VDR-expressing WT145 cells, 1,25D and its synthetic analog EB1089 induce growth arrest and transcriptionally upregulate the well-characterized VDR target gene CYP24. 1,25D also induces apoptosis in WT145 cells through activation of initiator and executioner caspases and the calcium-dependent protease calpain. We also demonstrate that WT145 cells express CYP27B1, the enzyme that converts 25-hydroxyvitamin D3 (25D) to 1,25D, and that 25D inhibits growth of these cells but does not trigger apoptosis or induce CYP24 expression. Comparative studies were conducted in KO240 cells, which were derived from VDR knockout mice and found to retain expression of CYP27B1. KO240 cells were not growth inhibited nor rendered apoptotic by any of the tested vitamin D compounds. These data conclusively demonstrate that VDR mediates the anti-proliferative and pro-apoptotic effects of vitamin D metabolites and analogs, but that the potency of a vitamin D compound to induce the VDR target gene CYP24 does not accurately predict its potency in mediating growth regulation. J. Cell. Biochem. 101: 1505,1519, 2007. © 2007 Wiley-Liss, Inc. [source]

    Serum concentrations of vitamin D and parathyroid hormone and prevalent metabolic syndrome among adults in the United States

    JOURNAL OF DIABETES, Issue 4 2009
    Earl S. FORD
    Abstract Background:, Some reports suggest that concentrations of vitamin D are inversely, whereas concentrations of parathyroid hormone (PTH) are directly, associated with prevalent metabolic syndrome. Because of lingering uncertainty about these associations, we examined the cross-sectional associations between serum concentrations of 25-hydroxyvitamin D3 and PTH with metabolic syndrome in a representative sample of adults in the US. Methods:, We used data from 1705 participants in the 2005,2006 National Health and Nutrition Examination Survey. Vitamin D was measured by radioimmunoassay, whereas PTH was measured using an electrochemiluminescent process. Results:, The mean concentration of vitamin D for participants with and without metabolic syndrome was 20.3 and 22.9 ng/mL, respectively (P = 0.001). The mean concentration of PTH for participants with and without metabolic syndrome was 44.5 and 41.0 pg/mL, respectively (P = 0.002). The age-adjusted mean concentrations of vitamin D (P for linear trend <0.001) decreased linearly, whereas PTH (P for linear trend = 0.002) increased linearly, as the number of components of metabolic syndrome increased. After adjusting for age, gender, physical activity, urinary albumin creatinine ratio, and concentrations of C-reactive protein and calcium, concentrations in the highest quintile of vitamin D [prevalence ratio (PR) = 0.59; 95% confidence interval (CI) 0.44,0.79], but not PTH (PR = 1.18; 95% CI 0.97,1.43), was significantly associated with prevalent metabolic syndrome. Conclusion:, Concentrations of vitamin D, but not PTH, were significantly associated with prevalent metabolic syndrome among US adults. [source]

    Bone mineral metabolism and histomorphometry in rats with cholestatic liver disease

    LIVER INTERNATIONAL, Issue 2 2002
    Zvi Ackerman
    Abstract: Background: The etiology of osteopenia in cholestatic liver disease is uncertain. An animal model is needed in order to study the efficacy of therapeutic agents. Aims: In order to characterise the bone disease in rats with cholestatic liver disease. Methods: Four-month old male Sprague,Dawley bile duct-ligated (BDL) and sham-operated (SO) rats were studied. Twenty-eight days after surgery serum osteocalcin, a bone-formation marker, urinary deoxypyridinoline (DPD) cross-links, a resorption marker, and 25-hydroxyvitamin D3 were determined. Static and dynamic (tetracycline-based) histomorphometric analysis was performed on femurs and tibiae. Results: All BDL rats developed biliary cirrhosis. Bile duct-ligated rats had lower bone mass, reflected in statistically significantly 13.5% lower femoral dry-weight, 16% lower femoral ash-weight, 42.7% lower tibial cancellous bone area and 19% lower trabecular thickness, compared with SO rats. Bile duct-ligated rats exhibited decreased bone formation manifested by statistically significantly 70% lower tetracycline double-labelling, 40% lower mineralising surface, 51% lower bone-formation rate and 47% lower osteocalcin compared with SO rats. Deoxypyridinoline levels were 20% lower in BDL rats. Bile duct-ligated rats had 52% lower serum 25-hydroxyvitamin D3 level, but no significant increase in cortical osteoid area. Conclusions: Bile duct-ligated rats develop osteopenia characterised by low bone-formation rate, and can be used for studying therapeutic agents for patients with cholestatic liver disease displaying similar bone changes. [source]

    3D-QSAR Studies on C24-Monoalkylated Vitamin D3 26,23-Lactones and their C2, -Modified Derivatives with Inhibitory Activity to Vitamin D Receptor

    MOLECULAR INFORMATICS, Issue 8-9 2010
    Jinhu Wang
    Abstract The ligand-based three-dimensional quantitative structure-activity relationship (3D-QSAR) for 82 inhibitors of 25-dehydro-1, -hydroxyvitamin D3 -26,23-lactone analogs has been studied by using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) models. The established CoMFA model in training set gives a cross-validated q2 value of 0.516 and a non-cross-validated rncv2 value of 0.667, while the CoMSIA model results in q2=0.517 and rncv2=0.632. In general, the predictive ability of the CoMFA model is superior to that of the CoMSIA model, with rpred2=0.639 for the CoMFA and rpred2=0.619 for the CoMSIA model. Based on the CoMFA contour maps, some key structural characters of vitamin D3 analogs responsible for inhibitory activity are identified, and some new C2, -modified 24-alkylvitamin D3 lactone analogs with high predicted pIC50 values are designed. The ligand functional group mutations by FEP simulation and docking studies reveal the rationality of the molecular design. [source]

    A Potential Role for Vitamin D on HIV Infection?

    NUTRITION REVIEWS, Issue 5 2006
    Eduardo Villamor MD
    Despite advances in the knowledge of vitamin D's potent immunomodulatory activity, its role on HIV disease progression is unknown. Decreased concentrations of 1,,25-hydroxyvitamin D3, or 1,25(OH)2D, the active form of vitamin D, have been reported among HIV-infected people and attributed to defects in renal hydroxylation and increased utilization. A few studies also described low levels of 25-hydroxyvitamin D3, 25(OH)D, the vitamin obtained from solar synthesis and diet. An inverse association between 1,25(OH)2D concentrations and mortality has been reported from a small cohort of HIV-infected adults, and some cross-sectional studies have indicated positive correlations between 1,25(OH)2D and CD4+ cell counts. Additional observational studies are needed to confirm the associations between vitamin D status and HIV disease progression. These investigations would provide useful insights on the potential role of vitamin D supplementation to HIV-infected persons and the planning of intervention trials. [source]

    Nutritional rickets and z scores for height in the United Arab Emirates: To D or not to D?

    PEDIATRICS INTERNATIONAL, Issue 4 2008
    Jaishen Rajah
    Abstract Background: Vitamin D deficiency is still prevalent worldwide, including the Middle East. A cohort of patients with nutritional rickets was treated with vitamin D2 (ergocalciferol) alone. After this intervention, patients were followed to document changes in z scores for height after treatment. The secondary aim was to determine the proportion of affected children who had vitamin D deficiency or calcium deficiency. Methods: Z score for height was calculated as the difference between the observed value and the median value, divided by the SD of the population. Z scores were compared in patients before and after treatment. Results: The improvement in z score after treatment was 0.86 ± 0.95. The 95% confidence interval for the mean difference was 1.32,0.40 (t = 3.95, P < 0.001). With a diagnostic cut-off for 25 hydroxyvitamin D3 (25D) deficiency of <25 nmol/L, only half were diagnosed with severe vitamin D deficiency. The remaining patients had presumable calcium deficiency. The alkaline phosphatase (ALP) was negatively correlated to z scores, implying that higher ALP concentrations predicted severe bone disease (lower z scores). The variables 25D and age were moderately and positively correlated (Pearson's r = 0.59, 95%CI: 0.15,0.84; P = 0.01), indicating that younger infants had the lowest 25D levels. Conclusion: Vitamin D alone was efficient in resolving radiological and biochemical disturbances as well as improving z scores for height in a cohort of children with nutritional rickets, which included patients with 25D deficiency as well as calcium deficiency. The results support the hypothesis of the interplay and continuum of 25D deficiency and calcium deficiency in the pathogenesis of rickets. [source]

    5,-dihydrotestosterone inhibits 1,,25-dihydroxyvitamin D3 -induced expression of CYP24 in human prostate cancer cells

    THE PROSTATE, Issue 3 2005
    Yan-Ru Lou
    Abstract BACKGROUND A cross-talk between 1,,25-dihydroxyvitamin D3 [1,,25-(OH)2D3] and 5,-dihydrotestosterone (DHT) in the growth inhibition has been demonstrated, but the mechanism is unknown. METHODS The expression of 25-hydroxyvitamin D3 24-hydroxylase (24-hydroxylase) was measured using a real-time quantitative RT-PCR assay and the catabolism of 1,,25-(OH)2D3 was measured using a radioreceptor assay. RESULTS Real-time RT-PCR showed that DHT at 1,100 nM significantly inhibited 1,,25-(OH)2D3 -induced expression of 24-hydroxylase in LNCaP cells. Furthermore, the catabolism of 1,,25-(OH)2D3 was decreased by 10 nM DHT. An androgen receptor (AR) antagonist, Casodex antagonized the DHT effect, whereas an AR agonist (due to the mutant AR in LNCaP cells) hydroxyflutamide did not. CONCLUSIONS We demonstrated, for the first time, that DHT reduces the ability of 1,,25-(OH)2D3 to induce 24-hydroxylase expression. Our results not only support the earlier finding of a cross-talk between androgen and vitamin D in human prostate cancer cells but also provide a possible mechanism how androgen and vitamin D signaling pathways may interact. © 2004 Wiley-Liss, Inc. [source]

    Structural basis of the histidine-mediated vitamin D receptor agonistic and antagonistic mechanisms of (23S)-25-dehydro-1,-hydroxyvitamin D3 -26,23-lactone

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2010
    Shinji Kakuda
    TEI-9647 antagonizes vitamin D receptor (VDR) mediated genomic actions of 1,,25(OH)2D3 in human cells but is agonistic in rodent cells. The presence of Cys403, Cys410 or of both residues in the C-terminal region of human VDR (hVDR) results in antagonistic action of this compound. In the complexes of TEI-9647 with wild-type hVDR (hVDRwt) and H397F hVDR, TEI-9647 functions as an antagonist and forms a covalent adduct with hVDR according to MALDI,TOF MS. The crystal structures of complexes of TEI-9647 with rat VDR (rVDR), H305F hVDR and H305F/H397F hVDR showed that the agonistic activity of TEI-9647 is caused by a hydrogen-bond interaction with His397 or Phe397 located in helix 11. Both biological activity assays and the crystal structure of H305F hVDR complexed with TEI-9647 showed that the interaction between His305 and TEI-9647 is crucial for antagonist activity. This study indicates the following stepwise mechanism for TEI-9647 antagonism. Firstly, TEI-9647 forms hydrogen bonds to His305, which promote conformational changes in hVDR and draw Cys403 or Cys410 towards the ligand. This is followed by the formation of a 1,4-Michael addition adduct between the thiol (,SH) group of Cys403 or Cys410 and the exo -methylene group of TEI-9647. [source]

    Crystallization and preliminary X-ray diffraction studies of vitamin D3 hydroxylase, a novel cytochrome P450 isolated from Pseudonocardia autotrophica

    ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 4 2009
    Yoshiaki Yasutake
    Vitamin D3 hydroxylase (Vdh) is a novel cytochrome P450 monooxygenase isolated from the actinomycete Pseudonocardia autotrophica and consisting of 403 amino-acid residues. Vdh catalyzes the activation of vitamin D3via sequential hydroxylation reactions: these reactions involve the conversion of vitamin D3 (cholecalciferol or VD3) to 25-hydroxyvitamin D3 [25(OH)VD3] and the subsequent conversion of 25(OH)VD3 to 1,,25-dihydroxyvitamin D3 [calciferol or 1,,25(OH)2VD3]. Overexpression of recombinant Vdh was carried out using a Rhodococcus erythropolis expression system and the protein was subsequently purified and crystallized. Two different crystal forms were obtained by the hanging-drop vapour-diffusion method at 293,K using polyethylene glycol as a precipitant. The form I crystal belonged to the trigonal space group P31, with unit-cell parameters a = b = 61.7, c = 98.8,Å. There is one Vdh molecule in the asymmetric unit, with a solvent content of 47.6%. The form II crystal was grown in the presence of 25(OH)VD3 and belonged to the orthorhombic system P212121, with unit-cell parameters a = 63.4, b = 65.6 c = 102.2,Å. There is one Vdh molecule in the asymmetric unit, with a solvent content of 46.7%. Native data sets were collected to resolutions of 1.75 and 3.05,Å for form I and form II crystals, respectively, using synchrotron radiation. The structure solution was obtained by the molecular-replacement method and model refinement is in progress for the form I crystal. [source]

    Expression of 25-hydroxyvitamin D3 -1,-hydroxylase in subcutaneous fat necrosis

    BRITISH JOURNAL OF DERMATOLOGY, Issue 2 2009
    A. Farooque
    Summary Background, The most serious complication of subcutaneous fat necrosis (SCFN), a rare condition of the newborn characterized by indurated purple nodules, is hypercalcaemia. However, the mechanism for this hypercalcaemia remains unclear. Objectives, To determine whether the hypercalcaemia associated with SCFN involves expression of the vitamin D-activating enzyme 25-hydroxyvitamin D3 -1,-hydroxylase (1,-hydroxylase) in affected tissue. Methods, Skin biopsies from two male patients with SCFN and hypercalcaemia were taken. The histological specimens were assessed using a polyclonal antibody against 1,-hydroxylase. Results, Histology in both cases showed strong expression of 1,-hydroxylase protein (brown staining) within the inflammatory infiltrate associated with SCFN. This was consistent with similar experiments in other granulomatous conditions. Conclusions, Hypercalcaemia in SCFN appears to be due to abundant levels of 1,-hydroxylase in immune infiltrates associated with tissue lesions. This is consistent with previous observations of extrarenal 1,-hydroxylase in skin from other granulomatous conditions such as sarcoidosis and slack skin disease. [source]