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Rapid genomic changes by mineralotropic hormones and kinase SIK inhibition drive coordinated renal Cyp27b1 and Cyp24a1 expression via CREB modules. J Biol Chem 2022; 298:102559. [DOI: 10.1016/j.jbc.2022.102559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 09/26/2022] [Accepted: 09/27/2022] [Indexed: 11/16/2022] Open
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Single bout of exercise triggers the increase of vitamin D blood concentration in adolescent trained boys: a pilot study. Sci Rep 2022; 12:1825. [PMID: 35115578 PMCID: PMC8814171 DOI: 10.1038/s41598-022-05783-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 01/17/2022] [Indexed: 02/07/2023] Open
Abstract
Vitamin D is necessary for musculoskeletal health, however, the supplementation of vitamin D above the sufficiency level does not bring additional bone mass density (BMD), unlike physical exercise which enhances the bone formatting process. Regular physical activity has been shown to upregulate VDR expression in muscles and to increase circulating vitamin D. Here we investigate whether a single bout of exercise might change 25(OH)D3 blood concentration and how it affects metabolic response to exercise. Twenty-six boys, 13.8 years old (SD ± 0.7) soccer players, participated in the study. The participants performed one of two types of exercise: the first group performed the VO2max test until exhaustion, and the second performed three times the repeated 30 s Wingate Anaerobic Test (WAnT). Blood was collected before, 15 min and one hour after the exercise. The concentration of 25(OH)D3, parathyroid hormone (PTH), interleukin-6 (IL-6), lactate, non-esterified fatty acids (NEFA) and glycerol were determined. 25(OH)D3 concentration significantly increased after the exercise in all boys. The most prominent changes in 25(OH)D3, observed after WAnT, were associated with the rise of PTH. The dimensions of response to the exercises observed through the changes in the concentration of 25(OH)D3, PTH, NEFA and glycerol were associated with the significant increases of IL-6 level. A single bout of exercise may increase the serum’s 25(OH)D3 concentration in young trained boys. The intensive interval exercise brings a more potent stimulus to vitamin D fluctuations in young organisms. Our results support the hypothesis that muscles may both store and release 25(OH)D3.
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Dzik KP, Kaczor JJ. Mechanisms of vitamin D on skeletal muscle function: oxidative stress, energy metabolism and anabolic state. Eur J Appl Physiol 2019; 119:825-839. [PMID: 30830277 PMCID: PMC6422984 DOI: 10.1007/s00421-019-04104-x] [Citation(s) in RCA: 140] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 02/13/2019] [Indexed: 02/08/2023]
Abstract
Purpose This review provides a current perspective on the mechanism of vitamin D on skeletal muscle function with the emphasis on oxidative stress, muscle anabolic state and muscle energy metabolism. It focuses on several aspects related to cellular and molecular physiology such as VDR as the trigger point of vitamin D action, oxidative stress as a consequence of vitamin D deficiency. Method The interaction between vitamin D deficiency and mitochondrial function as well as skeletal muscle atrophy signalling pathways have been studied and clarified in the last years. To the best of our knowledge, we summarize key knowledge and knowledge gaps regarding the mechanism(s) of action of vitamin D in skeletal muscle. Result Vitamin D deficiency is associated with oxidative stress in skeletal muscle that influences the mitochondrial function and affects the development of skeletal muscle atrophy. Namely, vitamin D deficiency decreases oxygen consumption rate and induces disruption of mitochondrial function. These deleterious consequences on muscle may be associated through the vitamin D receptor (VDR) action. Moreover, vitamin D deficiency may contribute to the development of muscle atrophy. The possible signalling pathway triggering the expression of Atrogin-1 involves Src-ERK1/2-Akt- FOXO causing protein degradation. Conclusion Based on the current knowledge we propose that vitamin D deficiency results from the loss of VDR function and it could be partly responsible for the development of neurodegenerative diseases in human beings.
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Affiliation(s)
- Katarzyna Patrycja Dzik
- Department of Neurobiology of Muscle, Gdansk University of Physical Education and Sport, Kazimierza Gorskiego 1, 80-336, Gdansk, Poland
| | - Jan Jacek Kaczor
- Department of Neurobiology of Muscle, Gdansk University of Physical Education and Sport, Kazimierza Gorskiego 1, 80-336, Gdansk, Poland.
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Bikle DD, Patzek S, Wang Y. Physiologic and pathophysiologic roles of extra renal CYP27b1: Case report and review. Bone Rep 2018; 8:255-267. [PMID: 29963603 PMCID: PMC6021194 DOI: 10.1016/j.bonr.2018.02.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/06/2018] [Accepted: 02/23/2018] [Indexed: 01/13/2023] Open
Abstract
Although the kidney was initially thought to be the sole organ responsible for the production of 1,25(OH)2D via the enzyme CYP27b1, it is now appreciated that the expression of CYP27b1 in tissues other than the kidney is wide spread. However, the kidney is the major source for circulating 1,25(OH)2D. Only in certain granulomatous diseases such as sarcoidosis does the extra renal tissue produce sufficient 1,25(OH)2D to contribute to the circulating levels, generally associated with hypercalcemia, as illustrated by the case report preceding the review. Therefore the expression of CYP27b1 outside the kidney under normal circumstances begs the question why, and in particular whether the extra renal production of 1,25(OH)2D has physiologic importance. In this chapter this question will be discussed. First we discuss the sites for extra renal 1,25(OH)2D production. This is followed by a discussion of the regulation of CYP27b1 expression and activity in extra renal tissues, pointing out that such regulation is tissue specific and different from that of CYP27b1 in the kidney. Finally the physiologic significance of extra renal 1,25(OH)2D3 production is examined, with special focus on the role of CYP27b1 in regulation of cellular proliferation and differentiation, hormone secretion, and immune function. At this point the data do not clearly demonstrate an essential role for CYP27b1 expression in any tissue outside the kidney, but several examples pointing in this direction are provided. With the availability of the mouse enabling tissue specific deletion of CYP27b1, the role of extra renal CYP27b1 expression in normal and pathologic states can now be addressed definitively.
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Affiliation(s)
- Daniel D Bikle
- Department of Medicine, Endocrine Research Unit, Veterans Affairs Medical Center, University of California San Francisco, United States
| | - Sophie Patzek
- Department of Medicine, Endocrine Research Unit, Veterans Affairs Medical Center, University of California San Francisco, United States
| | - Yongmei Wang
- Department of Medicine, Endocrine Research Unit, Veterans Affairs Medical Center, University of California San Francisco, United States
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Jones G, Kottler ML, Schlingmann KP. Genetic Diseases of Vitamin D Metabolizing Enzymes. Endocrinol Metab Clin North Am 2017; 46:1095-1117. [PMID: 29080636 DOI: 10.1016/j.ecl.2017.07.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Vitamin D metabolism involves 3 highly specific cytochrome P450 (CYP) enzymes (25-hydroxylase, 1α-hydroxylase, and 24-hydroxylase) involved in the activation of vitamin D3 to the hormonal form, 1,25-(OH)2D3, and the inactivation of 1,25-(OH)2D3 to biliary excretory products. Mutations of the activating enzymes CYP2R1 and CYP27B1 cause lack of normal 1,25-(OH)2D3 synthesis and result in rickets whereas mutations of the inactivating enzyme CYP24A1 cause build-up of excess 1,25-(OH)2D3 and result in hypercalcemia, nephrolithiasis, and nephrocalcinosis. This article reviews the literature for 3 clinical conditions. Symptoms, diagnosis, treatment, and management of vitamin D-dependent rickets and idiopathic infantile hypercalcemia are discussed.
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Affiliation(s)
- Glenville Jones
- Department of Biomedical and Molecular Sciences, Queen's University, Room 650, Botterell Hall, Kingston, ON K7L 3N6, Canada.
| | - Marie Laure Kottler
- Department of Genetics, University de Basse-Normandie, National Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Caen University Hospital, Avenue de la Côte de Nacre, 14033 Caen, France; Team 7450 BIOTARGEN, Caen-Normandy University, Esplanade de la Paix, 14032 Caen, France
| | - Karl Peter Schlingmann
- Department of General Pediatrics, University Children's Hospital, Waldeyerstr. 22, D-48149 Muenster, Germany
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Parker VJ, Rudinsky AJ, Chew DJ. Vitamin D metabolism in canine and feline medicine. J Am Vet Med Assoc 2017; 250:1259-1269. [DOI: 10.2460/javma.250.11.1259] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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7
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Zagrodna A, Jóźków P, Mędraś M, Majda M, Słowińska-Lisowska M. Sclerostin as a novel marker of bone turnover in athletes. Biol Sport 2016; 33:83-7. [PMID: 26929475 PMCID: PMC4763547 DOI: 10.5604/20831862.1194125] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 05/19/2015] [Accepted: 08/21/2015] [Indexed: 11/28/2022] Open
Abstract
Sclerostin is a protein secreted by osteocytes that acts as an inhibitor of bone formation. It has been shown that physical activity affects sclerostin concentration and thus bone remodelling. The aim of the study was to evaluate serum concentrations of sclerostin, selected bone turnover markers (PTH, P1NP), 25(OH)D3 and the intake of calcium and vitamin D in physically active versus sedentary men. A total of 59 healthy men aged 17-37 were enrolled in the study (43 athletes and 16 non-athletes). The mean sclerostin concentration in the group of athletes (A) was significantly higher than in non-athletes (NA) (35.3±8.9 vs 28.0±5.6 pmol·l-1, p= 0.004). A compared with NA had higher concentrations of P1NP (145.6±77.5 vs 61.2±22.3 ng·ml-1, p= <0.0001) and 25(OH)D3 (16.9±8.4 vs 10.3±4.3 ng·ml-1, p= 0.004) and lower concentrations of PTH (25.8±8.3 vs 38.2±11.5 pg·ml-1, p= <0.0001). Vitamin D deficiency was found in 77% of A and 100% of NA. A and NA had similar daily energy intake. They did not differ as to the intake of calcium and vitamin D. We observed a negative correlation between the serum concentrations of sclerostin and calcium in the studied subjects. Our results suggest that regular, long-lasting physical training may be associated with higher concentration of sclerostin. It seems that increased sclerostin is not related to other bone turnover markers (PTH, P1NP).
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Affiliation(s)
- A Zagrodna
- Department of the Biological Basis of Sport, Wrocław University of Physical Education, Poland
| | - P Jóźków
- Department of the Biological Basis of Sport, Wrocław University of Physical Education, Poland
| | - M Mędraś
- Department of the Biological Basis of Sport, Wrocław University of Physical Education, Poland
| | - M Majda
- Lower Silesia Specialist Hospital, Tadeusz Marciniak Centre For Emergency Medicine, Poland
| | - M Słowińska-Lisowska
- Department of the Biological Basis of Sport, Wrocław University of Physical Education, Poland
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Abstract
The vitamin D signal transduction system involves a series of cytochrome P450-containing sterol hydroxylases to generate and degrade the active hormone, 1α,25-dihydroxyvitamin D3, which serves as a ligand for the vitamin D receptor-mediated transcriptional gene expression described in companion articles in this review series. This review updates our current knowledge of the specific anabolic cytochrome P450s involved in 25- and 1α-hydroxylation, as well as the catabolic cytochrome P450 involved in 24- and 23-hydroxylation steps, which are believed to initiate inactivation of the vitamin D molecule. We focus on the biochemical properties of these enzymes; key residues in their active sites derived from crystal structures and mutagenesis studies; the physiological roles of these enzymes as determined by animal knockout studies and human genetic diseases; and the regulation of these different cytochrome P450s by extracellular ions and peptide modulators. We highlight the importance of these cytochrome P450s in the pathogenesis of kidney disease, metabolic bone disease, and hyperproliferative diseases, such as psoriasis and cancer; as well as explore potential future developments in the field.
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Affiliation(s)
- Glenville Jones
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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Sclerostin alters serum vitamin D metabolite and fibroblast growth factor 23 concentrations and the urinary excretion of calcium. Proc Natl Acad Sci U S A 2013; 110:6199-204. [PMID: 23530237 DOI: 10.1073/pnas.1221255110] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Inactivating mutations of the SOST (sclerostin) gene are associated with overgrowth and sclerosis of the skeleton. To determine mechanisms by which increased amounts of calcium and phosphorus are accreted to enable enhanced bone mineralization in the absence of sclerostin, we measured concentrations of calciotropic and phosphaturic hormones, and urine and serum calcium and inorganic phosphorus in mice in which the sclerostin (sost) gene was replaced by the β-D-galactosidase (lacZ) gene in the germ line. Knockout (KO) (sost(-/-)) mice had increased bone mineral density and content, increased cortical and trabecular bone thickness, and greater net bone formation as a result of increased osteoblast and decreased osteoclast surfaces compared with wild-type (WT) mice. β-Galactosidase activity was detected in osteocytes of sost KO mice but was undetectable in WT mice. Eight-week-old, male sost KO mice had increased serum 1α,25-dihydroxyvitamin D, decreased 24,25-dihydroxyvitamin D, decreased intact fibroblast growth factor 23, and elevated inorganic phosphorus concentrations compared with age-matched WT mice. 25-Hydroxyvitamin D 1α-hydroxylase cytochrome P450 (cyp27B1) mRNA was increased in kidneys of sost KO mice compared with WT mice. Treatment of cultured proximal tubule cells with mouse recombinant sclerostin decreased cyp27B1 mRNA transcripts. Urinary calcium and renal fractional excretion of calcium were decreased in sost KO mice compared with WT mice. Sost KO and WT mice had similar serum calcium and parathyroid hormone concentrations. The data show that sclerostin not only alters bone mineralization, but also influences mineral metabolism by altering concentrations of hormones that regulate mineral accretion.
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Abstract
Vitamin D deficiency is a preventable health problem. Vitamin D deficiency among pregnant women is frequent in many populations over the world. Research indicates that adequate vitamin D intake in pregnancy is optimal for maternal, fetal and child health. Adverse health outcomes during pregnancy are preeclampsia; gestational diabetes mellitus and caesarean section. Consequences in newborns are low birth weight, neonatal rickets, a risk of neonatal hypocalcaemia, asthma and/or type 1 diabetes. Vitamin D deficiency during pregnancy is the origin for a host of future perils for the child, especially effect on neurodevelopment and immune system. Some of this damage done by maternal Vitamin D deficiency gets evident after many years. Therefore, prevention of vitamin D deficiency among pregnant women is essential. The currently recommended supplementation amount of vitamin D is not sufficient to maintain a value of 25 hydroxy vitamin D above 30 ng/ml, during pregnancy. Studies are underway to establish the recommended daily doses of vitamin D in pregnant women. Clearly, further investigation is required into the effects of vitamin D, of vitamin D supplementation, and of vitamin D analogs for improvement in human health generally and mothers and children specifically. This review discusses vitamin D metabolism, dietary requirements and recommendations and implications of vitamin D deficiency during pregnancy and lactation.
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Affiliation(s)
- Manila Kaushal
- Department of Obsteterics and Gynaecology, MGM Medical College, Indore, Madhya Pradesh, India
| | - Navneet Magon
- Department of Obstetrics and Gynaecology, Obstetrician, Gynaecologist and Endoscopic Surgeon, Air Force Hospital, Kanpur, Uttar Pradesh, India
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Kumar R, Tebben PJ, Thompson JR. Vitamin D and the kidney. Arch Biochem Biophys 2012; 523:77-86. [PMID: 22426203 PMCID: PMC3361542 DOI: 10.1016/j.abb.2012.03.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 03/01/2012] [Accepted: 03/02/2012] [Indexed: 12/22/2022]
Abstract
The kidney is essential for the maintenance of normal calcium and phosphorus homeostasis. Calcium and inorganic phosphorus are filtered at the glomerulus, and are reabsorbed from tubular segments by transporters and channels which are regulated by 1α,25-dihydroxyvitamin (1α,25(OH)(2)D) and parathyroid hormone (PTH). The kidney is the major site of the synthesis of 1α,25(OH)(2)D under physiologic conditions, and is one of the sites of 24,25-dihydroxyvitamin D (24,25(OH)(2)D) synthesis. The activity of the 25(OH)D-1α-hydroxylase, the mixed function oxidase responsible for the synthesis of 1α,25(OH)(2)D, is regulated by PTH, 1α,25(OH)(2)D, fibroblast growth factor 23 (FGF23), inorganic phosphorus and other growth factors. Additionally, the vitamin D receptor which binds to, and mediates the activity of 1α,25(OH)(2)D, is widely distributed in the kidney. Thus, the kidney, by regulating multiple transport and synthetic processes is indispensible in the maintenance of mineral homeostasis in physiological states.
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Affiliation(s)
- Rajiv Kumar
- Division of Nephrology and Hypertension, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
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Ritter CS, Haughey BH, Armbrecht HJ, Brown AJ. Distribution and regulation of the 25-hydroxyvitamin D3 1α-hydroxylase in human parathyroid glands. J Steroid Biochem Mol Biol 2012; 130:73-80. [PMID: 22326730 DOI: 10.1016/j.jsbmb.2012.01.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 01/12/2012] [Accepted: 01/20/2012] [Indexed: 01/22/2023]
Abstract
Parathyroid glands express the 25-hydroxyvitamin D(3) 1α-hydroxylase (1αOHase). 1,25-dihydroxyvitamin D(3) (calcitriol) synthesized by extrarenal tissues generally does not enter the circulation, but plays an autocrine/paracrine role specific to the cell type, and is regulated by the needs of that particular cell. While the role of calcitriol produced in the parathyroid glands presumably is to suppress PTH and cell growth, its regulation in this cell type has not been defined. In the present study, we found that regulation of the human parathyroid 1αOHase differs from the renal enzyme in that it is induced by FGF-23 and extracellular calcium. Hyperplastic parathyroid glands from patients with chronic kidney failure normally display a heterogeneous cellularity. We found that the 1αOHase is expressed at much higher levels in oxyphil cells than in chief cells in these patients. Recent findings indicate that oxyphil cell content is increased by treatment with calcium receptor activators (calcimimetics). Here, we demonstrate that the calcimimetic cinacalcet increases the expression of 1αOHase in human parathyroid cultures. Additionally, we found that the 1αOHase in human parathyroid cultures is functionally active, as evidenced by the ability of the enzyme to 1-hydroxylate 25(OH)D(3) in parathyroid monolayers. Calcium, as well as cinacalcet, also induced expression of the degradation enzyme 24-hydroxylase, indicating the presence of a negative feedback system in the parathyroid cells. Therefore, local production of 1αOHase suggests an autocrine/paracrine role in regulating parathyroid function and may mediate, in part, the suppression of PTH by calcium and FGF-23.
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Affiliation(s)
- Cynthia S Ritter
- Renal Division, Washington University School of Medicine, St. Louis, MO 63110, United States.
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Tebben PJ, Milliner DS, Horst RL, Harris PC, Singh RJ, Wu Y, Foreman JW, Chelminski PR, Kumar R. Hypercalcemia, hypercalciuria, and elevated calcitriol concentrations with autosomal dominant transmission due to CYP24A1 mutations: effects of ketoconazole therapy. J Clin Endocrinol Metab 2012; 97:E423-7. [PMID: 22337913 PMCID: PMC3319216 DOI: 10.1210/jc.2011-1935] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Mutations of the CYP24A1 gene, which encodes the 1,25-dihydroxyvitamin D-24-hydroxylase cytochrome P450, Cyp24A1, are predicted to result in elevated 1,25-dihydroxyvitamin D concentrations, hypercalcemia, hypercalciuria, nephrolithiasis, and bone disease. Treatment of hypercalcemia associated with CYP24A1 gene mutations has not been described. METHODS The genetic basis of a syndrome in a 44-yr-old Caucasian male characterized by intermittent hypercalcemia, hypercalciuria, elevated serum 1,25-dihydroxyvitamin D, undetectable serum 24,25-dihydroxyvitamin D, metabolically active nephrolithiasis, and reduced bone mineral density of the lumbar spine was examined. Sequencing of the CYP24A1 gene and biochemical and genetic analysis of seven family members in three generations was carried out. Because of hypercalcemia, hypercalciuria, and metabolically active nephrolithiasis, the patient was treated with a cytochrome 3A inhibitor, ketoconazole, 200 mg orally every 8 h, for 2 months. RESULTS The sequence of the CYP24A1 gene showed two canonical splice junction mutations in the proband. Analysis of family members showed a phenotype associated one or both mutations, suggesting autosomal dominant transmission with partial penetrance of the trait. After therapy with ketoconazole, statistically significant reductions in previously elevated urinary calcium into the normal range were noted. Previously elevated serum 1,25-dihydroxyvitamin D and calcium concentrations decreased, and previously decreased PTH concentrations increased into the normal range, but the differences were not statistically significant. CONCLUSIONS In a syndrome characterized by intermittent hypercalcemia, hypercalciuria, elevated 1,25-dihydroxyvitamin D, undetectable 24,25-dihydroxyvitamin D concentrations, splice junction mutations of the CYP24A1 gene, and autosomal dominant transmission of the trait, treatment with ketoconazole is useful in reducing urinary calcium.
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Zúñiga S, Firrincieli D, Housset C, Chignard N. Vitamin D and the vitamin D receptor in liver pathophysiology. Clin Res Hepatol Gastroenterol 2011; 35:295-302. [PMID: 21440524 DOI: 10.1016/j.clinre.2011.02.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 02/03/2011] [Accepted: 02/09/2011] [Indexed: 02/07/2023]
Abstract
Vitamin D through the vitamin D nuclear receptor (VDR) plays a key role in mineral ion homeostasis. The liver is central in vitamin D synthesis, however the direct involvement of the vitamin D-VDR axis on the liver remains to be evaluated. In this review, we will describe vitamin D metabolism and the mechanisms of homeostatic control. We will also address the associations between the vitamin D-VDR axis and pathological liver entities, such as non-alcoholic fatty liver disease, autoimmune liver disease, viral hepatitis and liver cancer. The link between liver diseases and the vitamin D-VDR axis will be discussed in light of evidences arising from in vitro and in vivo studies. Finally, we will consider the therapeutic potential of the vitamin D-VDR axis in liver diseases.
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Affiliation(s)
- Silvia Zúñiga
- UPMC University Paris 06, UMR_S 938, CdR Saint-Antoine, 75005 Paris, France
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Mulligan ML, Felton SK, Riek AE, Bernal-Mizrachi C. Implications of vitamin D deficiency in pregnancy and lactation. Am J Obstet Gynecol 2010; 202:429.e1-9. [PMID: 19846050 DOI: 10.1016/j.ajog.2009.09.002] [Citation(s) in RCA: 220] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 06/26/2009] [Accepted: 09/01/2009] [Indexed: 10/20/2022]
Abstract
Vitamin D is an essential fat soluble vitamin and a key modulator of calcium metabolism in children and adults. Because calcium demands increase in the third trimester of pregnancy, vitamin D status becomes crucial for maternal health, fetal skeletal growth, and optimal maternal and fetal outcomes. Vitamin D deficiency is common in pregnant women (5-50%) and in breastfed infants (10-56%), despite the widespread use of prenatal vitamins, because these are inadequate to maintain normal vitamin D levels (>or=32 ng/mL). Adverse health outcomes such as preeclampsia, low birthweight, neonatal hypocalcemia, poor postnatal growth, bone fragility, and increased incidence of autoimmune diseases have been linked to low vitamin D levels during pregnancy and infancy. Studies are underway to establish the recommended daily doses of vitamin D in pregnant women. This review discusses vitamin D metabolism and the implications of vitamin D deficiency in pregnancy and lactation.
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Abstract
Phosphate is critical for the maintenance of skeletal integrity, is a necessary component of important biomolecules, and is central to signal transduction and cell metabolism. It is becoming clear that endocrine communication between the skeleton, kidney, and the intestine is involved in maintaining appropriate serum phosphate concentrations, and that the kidney is the primary site for minute-to-minute regulation of phosphate levels. The identification of genetic alterations in Mendelian disorders of hypophosphatemia and hyperphosphatemia has led to the isolation of novel genes and the identification of new roles for existing proteins--such as fibroblast growth factor 23 and its processing systems, the co-receptor alpha-klotho, and phosphate transporters--in the control of renal phosphate handling. Recent findings also indicate that fibroblast growth factor 23 has feedback mechanisms involving parathyroid hormone and vitamin D that control phosphate homeostasis. This Review will highlight genetic, in vitro and in vivo findings, and will discuss how these clinical and experimental discoveries have uncovered novel aspects of renal phosphate handling and opened new research and therapeutic avenues.
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Li J, Byrne ME, Chang E, Jiang Y, Donkin SS, Buhman KK, Burgess JR, Teegarden D. 1alpha,25-Dihydroxyvitamin D hydroxylase in adipocytes. J Steroid Biochem Mol Biol 2008; 112:122-6. [PMID: 18840526 PMCID: PMC2602794 DOI: 10.1016/j.jsbmb.2008.09.006] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 06/02/2008] [Accepted: 09/11/2008] [Indexed: 12/15/2022]
Abstract
High vitamin D intake is associated with reduced insulin resistance. Expression of extra-renal 1alpha,25-dihydroxyvitamin D hydroxylase (1alpha-hydroxylase) has been reported in several tissues and contributes to local synthesis of 1alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D) from the substrate 25-hydroxyvitamin D (25OHD). Expression and dietary regulation of 1alpha-hydroxylase in tissues associated with energy metabolism, including adipose tissue, has not been assessed. Male Wistar rats were fed a high calcium (1.5%) and high vitamin D (10,000IU/kg) or a low calcium (0.25%), low vitamin D (400IU/kg) with either a high fat (40% energy) or high sucrose (66% energy) dietary background for 14 weeks. Expression of 1alpha-hydroxylase, assessed by real time PCR, was detected in adipose tissue and did not differ with dietary level of calcium and vitamin D. 1alpha-Hydroxylase mRNA was also detected in 3T3-L1 preadipocytes and 25OHD treatment at 10nM levels induced 1,25(OH)(2)D responsive gene, CYP24, and this response was reduced in the presence of the p450 inhibitor, ketoconazole. In addition, (3)H 25OHD was converted to (3)H 1,25(OH)(2)D in intact 3T3-L1 preadipocytes. Cumulatively, these results demonstrate that 1alpha-hydroxylase is expressed in adipose tissue and is functional in cultured adipocytes. Thus, the capacity for local production may play a role in regulating adipocyte growth and metabolism.
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Affiliation(s)
| | | | | | | | | | | | | | - Dorothy Teegarden
- Corresponding Author: Dorothy Teegarden, 700 W. State St., Purdue University, West Lafayette IN 47907, , 765-494-8246, 765-494-0906
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Abstract
The vitamin D endocrine system is known for its essential role in calcium homeostasis and bone metabolism, and induces cell differentiation, inhibits cell growth, controls other hormonal systems, and modulates the immune response. Vitamin D(3) is a prohormone that is taken up by diet or synthesized in ultraviolet radiation-exposed skin and metabolically converted to the active metabolite, 1alpha,25-dihydroxyvitamin D(3). This nuclear hormone binds with high affinity the nuclear receptor vitamin D receptor. More than 3000 synthetic analogs of 1alpha,25(OH)(2)D(3) are known. This review aims to provide an overview on vitamin D signaling from the skin perspective.
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Affiliation(s)
- Carsten Carlberg
- Life Sciences Research Unit, Universitè of Luxembourg, 162A, Avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg.
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Abstract
The vitamin D endocrine system plays an essential role in calcium homeostasis and bone metabolism, but research during the past two decades has revealed a diverse range of biological actions that include induction of cell differentiation, inhibition of cell growth, immunomodulation, and control of other hormonal systems. Vitamin D itself is a prohormone that is metabolically converted to the active metabolite, 1,25-dihydroxyvitamin D [1,25(OH)(2)D]. This vitamin D hormone activates its cellular receptor (vitamin D receptor or VDR), which alters the transcription rates of target genes responsible for the biological responses. This review focuses on several recent developments that extend our understanding of the complexities of vitamin D metabolism and actions: the final step in the activation of vitamin D, conversion of 25-hydroxyvitamin D to 1,25(OH)(2)D in renal proximal tubules, is now known to involve facilitated uptake and intracellular delivery of the precursor to 1alpha-hydroxylase. Emerging evidence using mice lacking the VDR and/or 1alpha-hydroxylase indicates both 1,25(OH)(2)D(3)-dependent and -independent actions of the VDR as well as VDR-dependent and -independent actions of 1,25(OH)(2)D(3). Thus the vitamin D system may involve more than a single receptor and ligand. The presence of 1alpha-hydroxylase in many target cells indicates autocrine/paracrine functions for 1,25(OH)(2)D(3) in the control of cell proliferation and differentiation. This local production of 1,25(OH)(2)D(3) is dependent on circulating precursor levels, providing a potential explanation for the association of vitamin D deficiency with various cancers and autoimmune diseases.
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Affiliation(s)
- Adriana S Dusso
- Renal Division, Washington University School of Medicine, St. Louis, MO 63110-1093, USA
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22
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Abstract
The vitamin D endocrine systems plays a critical role in calcium and phosphate homeostasis. The active form of vitamin D, 1, 25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], binds with high affinity to a specific cellular receptor that acts as a ligand-activated transcription factor. The activated vitamin D receptor (VDR) dimerizes with another nuclear receptor, the retinoid X receptor (RXR), and the heterodimer binds to specific DNA motifs (vitamin D response elements, VDREs) in the promoter region of target genes. This heterodimer recruits nuclear coactivators and components of the transcriptional preinitiation complex to alter the rate of gene transcription. 1,25(OH)(2)D(3) also binds to a cell-surface receptor that mediates the activation of second messenger pathways, some of which may modulate the activity of the VDR. Recent studies with VDR-ablated mice confirm that the most critical role of 1, 25(OH)(2)D(3) is the activation of genes that control intestinal calcium transport. However, 1,25(OH)(2)D(3) can control the expression of many genes involved in a plethora of biological actions. Many of these nonclassic responses have suggested a number of therapeutic applications for 1,25(OH)(2)D(3) and its analogs.
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Affiliation(s)
- A J Brown
- Renal Division, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Affiliation(s)
- N H Bell
- Department of Medicine, Medical University of South Carolina, Ralph H. Johnson Department of Veterans Affairs Medical Center, Charleston 29401-5799, USA
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24
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The vitamin D endocrine system and its therapeutic potential. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0065-2490(96)80007-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
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Okuda K, Usui E, Ohyama Y. Recent progress in enzymology and molecular biology of enzymes involved in vitamin D metabolism. J Lipid Res 1995. [DOI: 10.1016/s0022-2275(20)41484-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Akiyoshi-Shibata M, Sakaki T, Ohyama Y, Noshiro M, Okuda K, Yabusaki Y. Further oxidation of hydroxycalcidiol by calcidiol 24-hydroxylase. A study with the mature enzyme expressed in Escherichia coli. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 224:335-43. [PMID: 7925346 DOI: 10.1111/j.1432-1033.1994.00335.x] [Citation(s) in RCA: 134] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The coding region of the cDNA for rat kidney calcidiol 24-hydroxylase (P450cc24), which is involved in calcium homeostasis in animals, was inserted into an expression vector pKK223-3. The recombinant plasmid was formed in a specific manner without deletion or substitution of any parts of the coding region of the cDNA. When the resulting plasmid was introduced into Escherichia coli JM109, the recombinant cells produced a protein which was immunoreactive to an antibody against P450cc24. When the cell-free extract of the transformed cells was incubated with calcidiol together with bovine adrenodoxin and NADPH-adrenodoxin reductase, not only hydroxycalcidiol but also other metabolites such as oxocalcidiol and oxohydroxycalcidiol were produced. Similarly, calcitriol was converted not only to calcitetrol but also to oxocalcitriol and oxohydroxycalcitriol. These results indicate that a single enzyme expressed in the bacteria is responsible for all these successive reactions.
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Gross M, Kumar R. Vitamin D Endocrine System and Calcium and Phosphorus Homeostasis. Compr Physiol 1992. [DOI: 10.1002/cphy.cp080238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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28
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Bailly du Bois M, Milet C, Garabedian M, Guillozo H, Martelly E, Lopez E, Balsan S. Calcium-dependent metabolism of 25-hydroxycholecalciferol in silver eel tissues. Gen Comp Endocrinol 1988; 71:1-9. [PMID: 3410288 DOI: 10.1016/0016-6480(88)90288-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We investigated the in vitro metabolism of [26,27-3H]-25-(OH)D3 in different eel tissues. After incubation with [3H]-25-(OH)D3, tissues were extracted with methanol-chloroform and chromatographed on Sephadex LH 20 columns. Two derivatives less polar than 25-(OH)D3 were detected, the first one being sensitive to KOH treatment. Three peaks more polar than 25-(OH)D3 were also found: peak I migrated close to the 24,25-(OH)2D3 area and was quantitatively the most important, but the presence of 24,25-(OH)2D3 could not be demonstrated; peak II migrated in the 1,25-(OH)2D3 region; and peak III had an elution position twice that of peak II. After 6-h incubation of tissues isolated from control eels, peak I was found in all tissues including intestine and gills. It was highest in pituitary gland and brain and lowest in ovaries and muscle. It was not significantly modified 20 days after ablation of the corpuscules of Stannius. In contrast, in vivo daily calcium chloride injection was followed 24 hr later by a significant increase in the [3H]-25-(OH)D3 conversion into peak I in gills, intestine, and the spinal cord and by an inhibition of this conversion in pituitary gland, skin, and muscle. The inhibition was found in all tissues after five daily calcium injections. Calcium injection had no effect on the in vitro metabolite synthesis by the corpuscules of Stannius. These results suggest that vitamin D is not metabolized in the same way in eel as in mammals and that this metabolism could in part be calcium dependent.
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29
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Engstrom GW, Goff JP, Horst RL, Reinhardt TA. Regulation of calf renal 25-hydroxyvitamin D-hydroxylase activities by calcium-regulating hormones. J Dairy Sci 1987; 70:2266-71. [PMID: 3693631 DOI: 10.3168/jds.s0022-0302(87)80286-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Parathyroid hormone and 1,25-dihydroxyvitamin D3 had opposite effects on calf renal 25-hydroxyvitamin D3 24-, 23-, and 1 alpha-hydroxylase activities. Parathyroid hormone administration increased renal 25-hydroxyvitamin D3-1 alpha-hydroxylase activity 7-fold while 25-hydroxyvitamin D3-23- and 24-hydroxylase activities were essentially the same as controls. Administration of 1,25-dihydroxyvitamin D3 increased 25-hydroxyvitamin D3-23-hydroxylase and 24-hydroxylase activities 4-fold and decreased 25-hydroxyvitamin D3-1 alpha-hydroxylase activity to undetectable concentrations. Vitamin D deficiency increased 25-hydroxyvitamin D3-1 alpha -hydroxylase activity 13-fold, and 25-hydroxyvitamin D3-23-hydroxylase and 24-hydroxylase activities were undetectable. These results confirm previous reports with regard to control of renal 25-hydroxyvitamin D3-24-hydroxylase and 1 alpha -hydroxylase in other species and represent new findings relative to the control of 25-hydroxyvitamin D3-23-hydroxylase. Plasma P was lower and 1,25-dihydroxyvitamin D3 higher in calves treated with parathyroid hormone, and Ca and 1,25-dihydroxyvitamin D3 were lower in the vitamin D-deficient calves. 1,25-Dihydroxyvitamin D3-treated calves had higher plasma P and lower Mg than controls. Further studies using this calf model should lead to better understanding of Ca-regulating hormones control of vitamin D metabolism.
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Affiliation(s)
- G W Engstrom
- National Animal Disease Center, US Department of Agriculture, Ames, IA 50010
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Ando M, Shimizu M, Matsui S, Sayato Y, Takeda M. Influence of cadmium on the metabolism of vitamin D3 in rats. Toxicol Appl Pharmacol 1987; 89:158-64. [PMID: 3037727 DOI: 10.1016/0041-008x(87)90036-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In order to obtain further information on the effects of cadmium (Cd) on the mechanism of activation of vitamin D3 in the kidney, the serum concentrations of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] and 24,25-dihydroxycholecalciferol [24,25(OH)2D3] were determined by radioimmunoassay techniques. The serum concentration of 1,25(OH)2D3 in Cd-exposed rats was always higher than that in control rats. The concentrations of serum 1,25(OH)2D3 in parathyroidectomized rats (PTX), both in the control and in the Cd-exposed groups, were markedly lower than those in non-PTX rats. On the other hand, the concentration of serum 24,25(OH)2D3 in Cd-exposed rats was less than that in control rats. In other words, the pathway from secretion of parathyroid hormone (PTH) to synthesis of 1,25(OH)2D3 or 24,25(OH)2D3 was normal, but the pathway from stimulation of PTH to secretion of PTH was abnormal. These results suggest that rats exposed to Cd for 90 days were in a state of either deficiency of 1,25(OH)2D3 or excess secretion of parathyroid hormone. Although hypophosphatemia occurred in the Cd-exposed rats, the 1,25(OH)2D3 serum level in rats was not increased by PTX. On the basis of these results, it is suggested that hypophosphatemia occurring after the exposure of rats to Cd is a secondary hypophosphatemia.
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31
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Vitamin D3 (Cholecalciferol). ACTA ACUST UNITED AC 1984. [DOI: 10.1016/s0099-5428(08)60205-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Tanaka Y, DeLuca HF. Stimulation of 1,25-dihydroxyvitamin D3 production by 1,25-dihydroxyvitamin D3 in the hypocalcaemic rat. Biochem J 1983; 214:893-7. [PMID: 6312966 PMCID: PMC1152329 DOI: 10.1042/bj2140893] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Serum 1,25-dihydroxyvitamin D3 concentration and renal 25-hydroxyvitamin D 1 alpha-hydroxylase activity were measured in rats fed various levels of calcium, phosphorus and vitamin D3. Both calcium deprivation and phosphorus deprivation greatly increased circulating levels of 1,25-dihydroxyvitamin D3. The circulating level of 1,25-dihydroxyvitamin D3 in rats on a low-calcium diet increased with increasing doses of vitamin D3, whereas it did not change in rats on a low-phosphorus diet given increasing doses of vitamin D3. In concert with these results, the 25-hydroxyvitamin D 1 alpha-hydroxylase activity was markedly increased by vitamin D3 administration to rats on a low-calcium diet, whereas the same treatment of rats on a low-phosphorus diet had no effect and actually suppressed the 1 alpha-hydroxylase in rats fed an adequate-calcium/adequate-phosphorus diet. The administration of 1,25-dihydroxyvitamin D3 to vitamin D-deficient rats on a low-calcium diet also increased the renal 25-hydroxy-vitamin D 1 alpha-hydroxylase activity. These results demonstrate that the regulatory action of 1,25-dihydroxyvitamin D3 on the renal 25-hydroxyvitamin D3 1 alpha-hydroxylase is complex and not simply a suppressant of this system.
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Sommerville BA, Harvey S, Chadwick A. Early changes in the adaptation to a low calcium diet in the chick. Calcif Tissue Int 1983; 35:339-43. [PMID: 6871764 DOI: 10.1007/bf02405055] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Twelve hours after the diet of 3-week-old chicks was changed from a 1% to a 0.1% concentration of calcium (Ca), the growth rate and circulating levels of growth hormone had fallen while renal 25-hydroxecholecalciferol-24-hydroxylase had risen. The amount of 47Ca incorporated into bone from an injection given 18 h previously was lower than in the control birds. Over the following 2 1/2 days on the low Ca diet, the renal 1-hydroxylase activity rose and the plasma prolactin level fell, but the other parameters moved back toward the control level. It was concluded that early adjustments in hormonal and mineral metabolism counteract the acute effects of a dietary Ca shortage until longer-term adaptive changes begin to compensate for a continuing Ca deficiency. The renal hydroxylase activities were not directly influenced by the level of circulating growth hormone or prolactin.
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Kumar R, Wiesner R, Scott M, Go VL. Physiology of 24,25-dihydroxyvitamin D3 in normal human subjects. THE AMERICAN JOURNAL OF PHYSIOLOGY 1982; 243:E370-4. [PMID: 6753604 DOI: 10.1152/ajpendo.1982.243.5.e370] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We determined the metabolic clearance and production rates of 24,25-dihydroxyvitamin D3 in four normal healthy adults. We also examined the excretion of radioactivity in stool, urine, and bile after the intravenous administration of 24,25-[3H]dihydroxyvitamin D3 to human subjects. 24,25-Dihydroxyvitamin D3 is rapidly cleared from the plasma with a half-life of approximately 390 +/- 25 min (mean +/- SE). The metabolic clearance rate of 24,25-dihydroxyvitamin D3 was 9.2 +/- 1.5 liters/day with a production rate of 26.4 +/- 7.2 micrograms/day (mean +/- SE). Within 1 day 13.0 +/- 4.2% (mean +/- SE) of the administered dose had appeared in the stool; by day 7, 48.8 +/- 2.7% of the dose had appeared in the feces. Within 24 hr, 6.4 +/- 0.8% of the administered dose appeared in the urine; 7.4 +/- 1.8% of the dose had appeared in the urine within 2 days. The biliary excretion of 24,25-dihydroxyvitamin D3 was studied in two subjects. By 8 h, 15.3 +/- 1.3% of the administered dose had appeared in the bile. The metabolites present in bile, feces, and urine were much more polar than 24,25-dihydroxyvitamin D3. These results demonstrate that 24,25-dihydroxyvitamin D3 is rapidly cleared from plasma and is excreted in the feces (probably via the bile) and urine of normal human subjects.
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35
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Warner M. Catalytic activity of partially purified renal 25-hydroxyvitamin D hydroxylases from vitamin D-deficient and vitamin D-replete rats. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)33613-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Kramer P, Schmidt-Lauber M, Langenheim N, Zwehl W, Sold G, Luig H, Matthaei D, Gröne HJ, Henning HV, Scheler F. [Reno-cardiac interactions in kidney failure (author's transl)]. KLINISCHE WOCHENSCHRIFT 1980; 58:1043-50. [PMID: 7005526 DOI: 10.1007/bf01476875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The high incidence of cardiac complications in endstage renal failure is not only related to the chronic pressure load of the left ventricle, although the proportion of patients with elevated blood pressure increases from 53 to 81% as reno-parenchymal disease progresses. Other factors as anemia, hyperparathyroidism, autonomic neuropathy and retention of electrolytes, metabolic products of toxins may cause damage to the heart. It is a matter of discussion whether uremia itself causes cardiomyopathy. Findings of a reduced Ca++-uptake during beta-adrenergic stimulation and a reduced reaction of (Na+, K+)-ATPase to digitalis suggest a basic change of myocardial membrane metabolism. Retention of an "endogenous digitalis" could help to explain some contradictory results.
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38
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Bikle DD. Studies of the chick renal mitochondrial 25-hydroxyvitamin D-3 24-hydroxylase. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 615:208-22. [PMID: 6775702 DOI: 10.1016/0005-2744(80)90024-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The vitamin D metabolite, 24,25-dihydroxyvitamin D-3, is made from 25-hydroxyvitamin D-3 by an enzyme (25-hydroxyvitamin D-3 24-hydroxylase) located in the renal mitochondria of vitamin D and calcium-replete chicks. The apparent Km for 25-hydroxyvitamin D-3 for this reaction was found to be 3 x 10(-7) M, although simple Michaelis-Menten kinetics were not observed at the higher substrate concentrations. Enzymatic activity was reduced by the mitochondrial metabolic inhibitors, antimycin A and dinitrophenol, as well as the inhibitors of mixed function oxidases, 2,4-dichloro-6-phenylphenoxyethylamine, 2-diethylaminoethyl-2,2-diphenylvalerate and metyrapone. Increasing the calcium concentration from 0 to 1 x 10(-5) M or the potassium concentration from 0 to 50 mM stimulated enzymatic activity 4- to 8-fold. Increasing the phosphate or acetate concentration from 0 to 50 mM stimulated enzymatic activity 6-fold. Raising the CO2/HCO3(-) content from 0/0 to 10%/10 mM stimulated enzymatic activity 5-fold. The effects of the cations were additive to those of the anions except in the presence of 50 mM phosphate or acetate. The effect of ions on 24,25-hydroxyvitamin D-3 production by renal mitochondria from vitamin D-replete chicks resembles the effect of these ions on production of 1,25-dihydroxyvitamin D-3 by renal mitochondria from vitamin D-deficient chicks, suggesting that the same mechanisms may be utilized.
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Bulla M, Stock GJ, Delling G, Hofmann H, Offermann G. [Influence of vitamin D therapy on renal osteodystrophy in children (author's transl)]. KLINISCHE WOCHENSCHRIFT 1980; 58:237-47. [PMID: 6249957 DOI: 10.1007/bf01476970] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Growth arrest and renal osteodystrophy is a major problem in renal insufficiency of children. The present report describes our experiences in managing renal osteodystrophy by using vitamin D3 for 24 months. Values in plasma of Ca, Mg, alkaline phosphatase, iPTH, 25-OH-D were determined regularly. Skeletal X-rays and analysis of iliac crest bone biopsies were obtained in each child. In treatment with vitamin D3 no hypercalcemia was seen despite high serum levels of 25-OH-D. Plasma-Ca, alkaline phosphatase, and iPTH normalized nearly. Radiographic abnormalities improved. Bone biopsies showed improvement in signs of secondary hyperparathyroidism and ostitis fibrosa, whereas osteomalacia remained unchanged. Osteoblast population showed a small reduction. No real increment in body growth was seen.
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Fox J, Care AD. Effect of low calcium and low phosphorus diets on the intestinal absorption of water in intact and parathyroidectomized pigs. Calcif Tissue Int 1980; 31:253-5. [PMID: 6781731 DOI: 10.1007/bf02407189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Young pigs, each surgically prepared beforehand with a Thiry-Vella loop of jejunum, were used to study the effect of feeding low calcium and low phosphorus diets on the intestinal absorption of water. Feeding a low phosphorus diet caused a highly significant stimulation in the absorption of water in parathyroid gland-intact and parathyroidectomized pigs; low calcium diets were without effect.
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DeLuca HF. Recent advances in our understanding of the vitamin D endocrine system. JOURNAL OF STEROID BIOCHEMISTRY 1979; 11:35-52. [PMID: 226791 DOI: 10.1016/0022-4731(79)90275-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Fox J, Care AD. Stimulation of duodenal and ileal absorption of phosphate in the chick by low-calcium and low-phosphorus diets. CALCIFIED TISSUE RESEARCH 1978; 26:243-5. [PMID: 750067 DOI: 10.1007/bf02013265] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The intestinal absorption of phosphate has been studied in vivo in the chick using ligated segments of duodenum and ileum. Feeding diets low in calcium (0.1%) and/or low in phosphorus (0.25%) caused an increase in the absorption of phosphate from both the duodenum and ileum. These changes are consistent with a putative increase in the renal production and mucosal uptake of 1,25-dihydroxycholecalciferol.
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45
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BJN volume 40 issue 3 Cover and Front matter. Br J Nutr 1978. [DOI: 10.1079/bjn19780139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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46
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Sommerville BA, Fox J, Care AD, Swaminathan R. The in vitro metabolism of 25-hydroxycholecalciferol by pig kidney: effect of low dietary levels of calcium and phosphorus. Br J Nutr 1978; 40:159-62. [PMID: 667000 DOI: 10.1079/bjn19780107] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
1. Homogenates of pig kidney incubated in vitro convert 25-hydroxycholecalciferol to the dihydroxymetabolites almost as efficiently as homogenates of chick kidney under similar conditions. 2. The cortex of the kidney carries out this conversion more efficiently than does the medulla. 3. Kidneys from pigs given low calcium or low phosphorus diets produce about 40% more 1,25-dihydroxycholecalciferol than those from pigs given diets containing normal levels of Ca and P.
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47
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Ribovich ML, DeLuca HF. Adaptation of intestinal calcium absorption: parathyroid hormone and vitamin D metabolism. Arch Biochem Biophys 1978; 188:157-63. [PMID: 209741 DOI: 10.1016/0003-9861(78)90368-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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48
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Ribovich ML, DeLuca HF. Effect of dietary calcium and phosphorus on intestinal calcium absorption and vitamin D metabolism. Arch Biochem Biophys 1978; 188:145-56. [PMID: 209740 DOI: 10.1016/0003-9861(78)90367-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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49
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Sommerville BA, Swaminathan R, Care AD. A comparison of the effects of dietary calcium and phosphorus deficiency on the in vitro and in vivo metabolism of 25-hydroxycholecalciferol in the chick. Br J Nutr 1978; 39:411-4. [PMID: 629930 DOI: 10.1079/bjn19780053] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
1. Young chicks fed a diet deficient in calcium showed an eightfold increase in the in vitro renal production of 1,25-dihydroxycholecalciferol (1,25-DHCC) and those fed a diet deficient in phosphorus showed a threefold increase when compared to chicks on a normal diet. 2. The in vivo accumulation of 1,25-DHCC in the gut mucosa was doubled in both low-Ca and low-P groups as was the rate of Ca absorption from the duodenum and the Ca-binding protein activity. The accumulation of 1,25-DHCC in bone increased threefold in the low-Ca group but showed no change in the low-P group. 3. It was concluded that the increased rate of Ca absorption found in dietary P deficiency depends rather upon the capacity of the gut mucosa to accumulate larger amounts of 1,25-DHCC than upon an increased renal production of this metabolite. The mechanism by which this is achieved is unknown, but it unlikely to be a general increase in availability of 1,25-DHCC since no rise occurred in bone 1,25-DHCC levels.
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50
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Baksi SN, Kenny AD. Effects of administration of antiestrogen (tamoxifen) in vivo on the metabolism of 25-hydroxyvitamin D3 in vitro in the Japanese quail. Biochem Pharmacol 1977; 26:2439-43. [PMID: 597332 DOI: 10.1016/0006-2952(77)90454-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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