1
|
Hartery SA, Kirby BJ, Walker EC, Kaufmann M, Jones G, St-Arnaud R, Sims NA, Kovacs CS. Loss of maternal calcitriol reversibly alters early offspring growth and skeletal development in mice. J Bone Miner Res 2024; 39:595-610. [PMID: 38477809 PMCID: PMC11206081 DOI: 10.1093/jbmr/zjae035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 02/01/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024]
Abstract
Ablation of Cyp27b1 eliminates calcitriol but does not disturb fetal mineral homeostasis or skeletal development. However, independent of fetal genotypes, maternal loss of Cyp27b1 altered fetal mineral and hormonal levels compared to offspring of WT dams. We hypothesized that these maternal influences would alter postnatal skeletal development. Cyp27b1 null and WT females were mated to bear only Cyp27b1+/- offspring. Forty-eight hours after birth, pups were cross-fostered to dams of the same or opposite genotype that bore them. Maternal and offspring samples were collected on days 21 (weaning) and 42. Offspring measurements included minerals and hormones, BMC by DXA, ash weight and mineral content, gene expression, 3-point bending tests, and microCT. Maternal lactational behavior was evaluated. Milk was analyzed for nutritional content. At day 21, offspring fostered by nulls, independent of birth dam, had ~20% lower weight, BMC, ash weight, and ash calcium than pups fostered by WT dams. Adjustment for body weight accounted for the lower BMC but not the lower ash weight and ash calcium. Hormones and serum/urine minerals did not differ across offspring groups. Offspring fostered by nulls had shorter femurs and lower cortical thickness, mean polar moment of inertia, cortical area, trabecular bone volume, and trabecular number. Dam lactational behaviors and milk nutritional content did not differ between groups. At day 42, body weight, ash weight, lengths, BMC, and tibial bone strength were no longer different between pups fostered by null vs WT dams. In summary, pups fostered by Cyp27b1 nulls, regardless of birth dam, have proportionately smaller skeletons at 21 d, impaired microstructure, but normal mineral homeostasis. The skeletal effects are largely recovered by day 42 (3 wk after weaning). In conclusion, maternal loss of calcitriol impairs early postnatal cortical bone growth and trabecular bone mass, but affected offspring catch up after weaning.
Collapse
Affiliation(s)
- Sarah A Hartery
- Faculty of Medicine – Endocrinology, Memorial University of Newfoundland, St. John’s, Newfoundland, A1B 3V6, Canada
| | - Beth J Kirby
- Faculty of Medicine – Endocrinology, Memorial University of Newfoundland, St. John’s, Newfoundland, A1B 3V6, Canada
| | - Emma C Walker
- St. Vincent’s Institute of Medical Research, the University of Melbourne, Melbourne, 3065, Australia
| | - Martin Kaufmann
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, K7L 3N6, Canada
| | - Glenville Jones
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, K7L 3N6, Canada
| | - René St-Arnaud
- Shriners Hospitals for Children – Canada and McGill University, Montréal, Quebec, H4A 0A9, Canada
| | - Natalie A Sims
- St. Vincent’s Institute of Medical Research, the University of Melbourne, Melbourne, 3065, Australia
| | - Christopher S Kovacs
- Faculty of Medicine – Endocrinology, Memorial University of Newfoundland, St. John’s, Newfoundland, A1B 3V6, Canada
| |
Collapse
|
2
|
Yadav PS, Kobelski MM, Martins JS, Tao T, Liu ES, Demay MB. Impaired Growth Plate Maturation in XLH Is due to Both Excess FGF23 and Decreased 1,25-Dihydroxyvitamin D Signaling. Endocrinology 2023; 165:bqad186. [PMID: 38066669 PMCID: PMC10732678 DOI: 10.1210/endocr/bqad186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Indexed: 12/22/2023]
Abstract
X-linked hypophosphatemia (XLH) is the most common form of hereditary hypophosphatemic rickets. The genetic basis for XLH is loss of function mutations in the phosphate-regulating endopeptidase X-linked (PHEX), which leads to increased circulating fibroblast growth factor 23 (FGF23). This increase in FGF23 impairs activation of vitamin D and attenuates renal phosphate reabsorption, leading to rickets. Previous studies have demonstrated that ablating FGF23 in the Hyp mouse model of XLH leads to hyperphosphatemia, high levels of 1,25-dihydroxyvitamin D, and is not associated with the development of rickets. Studies were undertaken to define a role for the increase in 1,25-dihydroxyvitamin D levels in the prevention of rickets in Hyp mice lacking FGF23. These mice were mated to mice lacking Cyp27b1, the enzyme responsible for activating vitamin D metabolites, to generate Hyp mice lacking both FGF23 and 1,25-dihydroxyvitamin D (FCH mice). Mice were fed a special diet to maintain normal mineral ion homeostasis. Despite normal mineral ions, Hyp mice lacking both FGF23 and Cyp27b1 developed rickets, characterized by an interrupted, expanded hypertrophic chondrocyte layer and impaired hypertrophic chondrocyte apoptosis. This phenotype was prevented when mice were treated with 1,25-dihydroxyvitamin D from day 2 until sacrifice on day 30. Interestingly, mice lacking FGF23 and Cyp27b1 without the PHEX mutation did not exhibit rickets. These findings define an essential PHEX-dependent, FGF23-independent role for 1,25-dihydroxyvitamin D in XLH and have important therapeutic implications for the treatment of this genetic disorder.
Collapse
Affiliation(s)
- Prem Swaroop Yadav
- Endocrine Unit, Massachusetts General Hospital, Boston, MA 02114, USA
- Harvard Medical School, Boston, MA 02115, USA
| | | | - Janaina S Martins
- Endocrine Unit, Massachusetts General Hospital, Boston, MA 02114, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Tao Tao
- Endocrine Unit, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Eva S Liu
- Harvard Medical School, Boston, MA 02115, USA
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women’s Hospital, Boston, MA 02115, USA
| | - Marie B Demay
- Endocrine Unit, Massachusetts General Hospital, Boston, MA 02114, USA
- Harvard Medical School, Boston, MA 02115, USA
| |
Collapse
|
3
|
McGuire BD, Dees A, Hao L, Buckendahl P, Ogilvie AR, Sun H, Rezaee T, Barrett LO, Karim L, Dominguez-Bello MG, Bello NT, Shapses SA. A vitamin D deficient diet increases weight gain and compromises bone biomechanical properties without a reduction in BMD in adult female mice. J Steroid Biochem Mol Biol 2023; 231:106314. [PMID: 37088440 DOI: 10.1016/j.jsbmb.2023.106314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 03/27/2023] [Accepted: 04/20/2023] [Indexed: 04/25/2023]
Abstract
Vitamin D contributes to the development and maintenance of bone. Evidence suggests vitamin D status can also alter energy balance and gut health. In young animals, vitamin D deficiency (VDD) negatively affects bone mineral density (BMD) and bone microarchitecture, and these effects may also occur due to chronic ethanol intake. However, evidence is limited in mature models, and addressing this was a goal of the current study. Seven-month-old female C57BL/6 mice (n = 40) were weight-matched and randomized to one of four ad libitum diets: control, alcohol (Alc), vitamin D deficient (0 IU/d), or Alc+VDD for 8 weeks. A purified (AIN-93) diet was provided with water or alcohol (10 %) ad libitum. Body weight and food intake were recorded weekly, and feces were collected at 0, 4, and 8 weeks. At the age of 9 months, intestinal permeability was assessed by oral gavage of fluorescein isothiocyanate-dextran. Thereafter, bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry. The microarchitecture of the distal femur was assessed by micro-computed tomography and biomechanical properties were evaluated by cyclic reference point indentation. VDD did not affect BMD or most bone microarchitecture parameters, however, the polar moment of inertia (p < 0.05) was higher in the VDD groups compared to vitamin D sufficient groups. VDD mice also had lower whole bone water content (p < 0.05) and a greater average unloading slope (p < 0.01), and energy dissipated (p < 0.01), indicating the femur displayed a brittle phenotype. In addition, VDD caused a greater increase in energy intake (p < 0.05), weight gain (p < 0.05), and a trend for higher intestinal permeability (p = 0.08). The gut microbiota of the VDD group had a reduction in alpha diversity (p < 0.05) and a lower abundance of ASVs from Rikenellaceae, Clostridia_UCG-014, Oscillospiraceae, and Lachnospiraceae (p < 0.01). There was little to no effect of alcohol supplementation on outcomes. Overall, these findings suggest that vitamin D deficiency causes excess weight gain and reduces the biomechanical strength of the femur as indicated by the higher average unloading slope and energy dissipated without an effect on BMD in a mature murine model.
Collapse
Affiliation(s)
- Brandon D McGuire
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ, USA
| | - Azra Dees
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ, USA
| | - Lihong Hao
- Department of Animal Sciences, Rutgers University, New Brunswick, NJ, USA
| | | | - Anna R Ogilvie
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ, USA
| | - Haipeng Sun
- Department of Microbiology and Biochemistry, New Brunswick, NJ, USA
| | - Taraneh Rezaee
- Department of Bioengineering, University of Massachusetts Dartmouth, Dartmouth, MA 02747, USA
| | - Leland O Barrett
- Department of Bioengineering, University of Massachusetts Dartmouth, Dartmouth, MA 02747, USA
| | - Lamya Karim
- Department of Bioengineering, University of Massachusetts Dartmouth, Dartmouth, MA 02747, USA
| | - Maria Gloria Dominguez-Bello
- Department of Microbiology and Biochemistry, New Brunswick, NJ, USA; NJ Institute of Food, Nutrition and Health, Rutgers University, New Brunswick, NJ, USA
| | - Nicholas T Bello
- Department of Animal Sciences, Rutgers University, New Brunswick, NJ, USA; NJ Institute of Food, Nutrition and Health, Rutgers University, New Brunswick, NJ, USA
| | - Sue A Shapses
- Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ, USA; NJ Institute of Food, Nutrition and Health, Rutgers University, New Brunswick, NJ, USA; Department of Medicine, Rutgers-Robert Wood Johnson Univ. Hospital, New Brunswick, NJ, USA.
| |
Collapse
|
4
|
Rebelos E, Tentolouris N, Jude E. The Role of Vitamin D in Health and Disease: A Narrative Review on the Mechanisms Linking Vitamin D with Disease and the Effects of Supplementation. Drugs 2023; 83:665-685. [PMID: 37148471 PMCID: PMC10163584 DOI: 10.1007/s40265-023-01875-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2023] [Indexed: 05/08/2023]
Abstract
Vitamin D insufficiency or deficiency (VDD) is a very prevalent condition in the general population. Vitamin D is necessary for optimal bone mineralization, but apart from the bone effects, preclinical and observational studies have suggested that vitamin D may have pleiotropic actions, whereas VDD has been linked to several diseases and higher all-cause mortality. Thus, supplementing vitamin D has been considered a safe and inexpensive approach to generate better health outcomes-and especially so in frail populations. Whereas it is generally accepted that prescribing of vitamin D in VDD subjects has demonstrable health benefits, most randomized clinical trials, although with design constraints, assessing the effects of vitamin D supplementation on a variety of diseases have failed to demonstrate any positive effects of vitamin D supplementation. In this narrative review, we first describe mechanisms through which vitamin D may exert an important role in the pathophysiology of the discussed disorder, and then provide studies that have addressed the impact of VDD and of vitamin D supplementation on each disorder, focusing especially on randomized clinical trials and meta-analyses. Despite there already being vast literature on the pleiotropic actions of vitamin D, future research approaches that consider and circumvent the inherent difficulties in studying the effects of vitamin D supplementation on health outcomes are needed to assess the potential beneficial effects of vitamin D. The evaluation of the whole vitamin D endocrine system, rather than only of 25-hydroxyvitamin D levels before and after treatment, use of adequate and physiologic vitamin D dosing, grouping based on the achieved vitamin D levels rather than the amount of vitamin D supplementation subjects may receive, and sufficiently long follow-up are some of the aspects that need to be carefully considered in future studies.
Collapse
Affiliation(s)
- Eleni Rebelos
- Turku PET Centre, University of Turku, Turku, Finland
- Institute of Clinical Physiology, National Research Council (CNR), Pisa, Italy
| | - Nikolaos Tentolouris
- 1st Department of Propaedeutic and Internal Medicine, Medical School, National and Kapodistrian University of Athens, Laiko General Hospital, Athens, Greece
| | - Edward Jude
- Department of Medicine, Tameside and Glossop Integrated Care NHS Foundation Trust, Ashton-under-Lyne , England.
- University of Manchester, Manchester, UK.
- Manchester Metropolitan University, Manchester, UK.
| |
Collapse
|
5
|
Walker V, Vuister GW. Biochemistry and pathophysiology of the Transient Potential Receptor Vanilloid 6 (TRPV6) calcium channel. Adv Clin Chem 2023; 113:43-100. [PMID: 36858649 DOI: 10.1016/bs.acc.2022.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
TRPV6 is a Transient Receptor Potential Vanilloid (TRPV) cation channel with high selectivity for Ca2+ ions. First identified in 1999 in a search for the gene which mediates intestinal Ca2+ absorption, its far more extensive repertoire as a guardian of intracellular Ca2+ has since become apparent. Studies on TRPV6-deficient mice demonstrated additional important roles in placental Ca2+ transport, fetal bone development and male fertility. The first reports of inherited deficiency in newborn babies appeared in 2018, revealing its physiological importance in humans. There is currently strong evidence that TRPV6 also contributes to the pathogenesis of some common cancers. The recently reported association of TRPV6 deficiency with non-alcoholic chronic pancreatitis suggests a role in normal pancreatic function. Over time and with greater awareness of TRPV6, other disease-associations are likely to emerge. Powerful analytical tools have provided invaluable insights into the structure and operation of TRPV6. Its roles in Ca2+ signaling and carcinogenesis, and the use of channel inhibitors in cancer treatment are being intensively investigated. This review first briefly describes the biochemistry and physiology of the channel, and analytical methods used to investigate these. The focus subsequently shifts to the clinical disorders associated with abnormal expression and the underlying pathophysiology. The aims of this review are to increase awareness of this channel, and to draw together findings from a wide range of sources which may help to formulate new ideas for further studies.
Collapse
Affiliation(s)
- Valerie Walker
- Department of Clinical Biochemistry, University Hospital Southampton NHS Foundation Trust, Southampton General Hospital, Southampton, United Kingdom.
| | - Geerten W Vuister
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical Biology, University of Leicester, Leicester, United Kingdom
| |
Collapse
|
6
|
Abstract
Fibroblast growth factor-23 (FGF23) controls the homeostasis of both phosphate and vitamin D. Bone-derived FGF23 can suppress the transcription of 1α-hydroxylase (1α(OH)ase) to reduce renal activation of vitamin D (1,25(OH)2D3). FGF23 can also activate the transcription of 24-hydroxylase to enhance the renal degradation process of vitamin D. There is a counter-regulation for FGF23 and vitamin D; 1,25(OH)2D3 induces the skeletal synthesis and the release of FGF23, while FGF23 can suppress the production of 1,25(OH)2D3 by inhibiting 1α(OH)ase synthesis. Genetically ablating FGF23 activities in mice resulted in higher levels of renal 1α(OH)ase, which is also reflected in an increased level of serum 1,25(OH)2D3, while genetically ablating 1α(OH)ase activities in mice reduced the serum levels of FGF23. Similar feedback control of FGF23 and vitamin D is also detected in various human diseases. Further studies are required to understand the subcellular molecular regulation of FGF23 and vitamin D in health and disease.
Collapse
Affiliation(s)
- Mohammed S Razzaque
- Department of Pathology, Lake Erie College of Osteopathic Medicine, Erie, Pennsylvania, USA
| |
Collapse
|
7
|
Trombetti A, Al-Daghri N, Brandi ML, Cannata-Andía JB, Cavalier E, Chandran M, Chaussain C, Cipullo L, Cooper C, Haffner D, Harvengt P, Harvey NC, Javaid MK, Jiwa F, Kanis JA, Laslop A, Laurent MR, Linglart A, Marques A, Mindler GT, Minisola S, Yerro MCP, Rosa MM, Seefried L, Vlaskovska M, Zanchetta MB, Rizzoli R. Interdisciplinary management of FGF23-related phosphate wasting syndromes: a Consensus Statement on the evaluation, diagnosis and care of patients with X-linked hypophosphataemia. Nat Rev Endocrinol 2022; 18:366-384. [PMID: 35484227 DOI: 10.1038/s41574-022-00662-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/10/2022] [Indexed: 12/17/2022]
Abstract
X-linked hypophosphataemia (XLH) is the most frequent cause of hypophosphataemia-associated rickets of genetic origin and is associated with high levels of the phosphaturic hormone fibroblast growth factor 23 (FGF23). In addition to rickets and osteomalacia, patients with XLH have a heavy disease burden with enthesopathies, osteoarthritis, pseudofractures and dental complications, all of which contribute to reduced quality of life. This Consensus Statement presents the outcomes of a working group of the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases, and provides robust clinical evidence on management in XLH, with an emphasis on patients' experiences and needs. During growth, conventional treatment with phosphate supplements and active vitamin D metabolites (such as calcitriol) improves growth, ameliorates leg deformities and dental manifestations, and reduces pain. The continuation of conventional treatment in symptom-free adults is still debated. A novel therapeutic approach is the monoclonal anti-FGF23 antibody burosumab. Although promising, further studies are required to clarify its long-term efficacy, particularly in adults. Given the diversity of symptoms and complications, an interdisciplinary approach to management is of paramount importance. The focus of treatment should be not only on the physical manifestations and challenges associated with XLH and other FGF23-mediated hypophosphataemia syndromes, but also on the major psychological and social impact of the disease.
Collapse
Affiliation(s)
- Andrea Trombetti
- Division of Bone Diseases, Department of Medicine, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
- Division of Geriatrics, Department of Rehabilitation and Geriatrics, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
| | - Nasser Al-Daghri
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | | | - Jorge B Cannata-Andía
- Hospital Universitario Central de Asturias (HUCA), Oviedo, Spain
- Universidad de Oviedo, Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain
- Retic REDinREN-RICORS, 2040-ISCIII, Madrid, Spain
| | - Etienne Cavalier
- Department of Clinical Chemistry, University of Liege, CHU de Liège, Liège, Belgium
| | - Manju Chandran
- Complicated Metabolic Bone Disorders Clinic, Osteoporosis and Bone Metabolism Unit, Department of Endocrinology, Singapore General Hospital, Singapore, Singapore
| | - Catherine Chaussain
- Université de Paris, Institut des maladies musculo-squelettiques, URP2496, UFR Odontologie, Montrouge, France
- AP-HP, FHU DDS-Net, Centre de Référence des Maladies Rares du Métabolisme du Calcium et du Phosphore, Service médecine bucco-dentaire, Hôpital Bretonneau, GH Paris Nord Université de Paris, Paris, France
| | - Lucia Cipullo
- Patient representative with XLH, Geneva, Switzerland
| | - Cyrus Cooper
- MRC Lifecourse Epidemiology Centre, University of Southampton, Southampton, UK
- NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK
- NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Dieter Haffner
- Department of Paediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany
| | - Pol Harvengt
- XLH Belgium, Belgian association of patients with XLH (a member of the International XLH Alliance), Waterloo, Belgium
| | - Nicholas C Harvey
- MRC Lifecourse Epidemiology Centre, University of Southampton, Southampton, UK
- NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | | | - Famida Jiwa
- Chair of the Committee of Patients Societies at the International Osteoporosis Foundation, Osteoporosis Canada, Toronto, Canada
| | - John A Kanis
- Mary McKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia
- Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Sheffield, UK
| | - Andrea Laslop
- Scientific Office, Federal Office for Safety in Health Care, Vienna, Austria
| | - Michaël R Laurent
- Centre for Metabolic Bone Diseases, University Hospitals Leuven, Leuven, Belgium
| | - Agnès Linglart
- Paris-Saclay University, INSERM U1185, Le Kremlin-Bicêtre, France
- AP-HP, endocrinology and diabetes for children, Reference centre for rare diseases of calcium and phosphate metabolism, OSCAR network, Platform of expertise for rare diseases of Paris Saclay Hospital, Bicêtre Paris Saclay Hospital, Le Kremlin-Bicêtre, France
| | - Andréa Marques
- Rheumatology Department, Centro Hospitalar Universitário de Coimbra, Coimbra, Portugal
- Health Sciences Research Unit: Nursing (UICiSA:E), Nursing School of Coimbra, Coimbra, Portugal
| | - Gabriel T Mindler
- Department of Paediatric Orthopaedics, Orthopaedic Hospital Speising, Vienna, Austria
- Vienna Bone and Growth Center, Vienna, Austria
| | - Salvatore Minisola
- Department of Clinical, Internal, Anaesthesiologic and Cardiovascular Sciences, 'Sapienza', Rome University, Rome, Italy
| | | | - Mario Miguel Rosa
- Departamento de Neurociências, Laboratório de Farmacologia Clínica E Terapêutica Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Lothar Seefried
- Orthopedic Department, University of Würzburg, Würzburg, Germany
| | - Mila Vlaskovska
- Medical Faculty, Department of Pharmacology, Medical University Sofia, Sofia, Bulgaria
| | - María Belén Zanchetta
- Instituto de Investigaciones Metabólicas (IDIM), Universidad del Salvador, Buenos Aires, Argentina
| | - René Rizzoli
- Division of Bone Diseases, Department of Medicine, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland.
| |
Collapse
|
8
|
Christakos S. Vitamin D: A Critical Regulator of Intestinal Physiology. JBMR Plus 2021; 5:e10554. [PMID: 34950825 PMCID: PMC8674771 DOI: 10.1002/jbm4.10554] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 08/10/2021] [Indexed: 01/01/2023] Open
Abstract
Calcium is required for the functioning of numerous biological processes and is essential for skeletal health. The major source of new calcium is from the diet. The central role of vitamin D in the maintenance of calcium homeostasis is to increase the absorption of ingested calcium from the intestine. The critical importance of vitamin D in this process is noted in the causal link between vitamin D deficiency and rickets, as well as in studies using genetically modified mice including mice deficient in the vitamin D receptor (Vdr null mice) or in the cytochrome P‐450 enzyme, 25‐hydroxyvitamin D3‐1α‐ hydroxylase (CYP27B1) that converts 25‐hydroxyvitamin D3 to the hormonally active form of vitamin D, 1,25‐dihydroxyvitamin D3 [1,25(OH)2D3] (Cyp27b1 null mice). When these mice are fed diets with high calcium and lactose, rickets is prevented. The studies using mouse models provide supporting evidence indicating that the major physiological function of 1,25(OH)2D3/VDR is intestinal calcium absorption. This review summarizes what is known about mechanisms involved in vitamin D‐regulated intestinal calcium absorption. Recent studies suggest that vitamin D does not affect a single entity, but that a complex network of calcium‐regulating components is involved in the process of 1,25(OH)2D3‐mediated active intestinal calcium absorption. In addition, numerous 1,25(OH)2D3 actions in the intestine have been described independent of calcium absorption. Although the translatability to humans requires further definition, an overview is presented that provides compelling evidence from the laboratory of 1,25(OH)2D3 intestinal effects, which include the regulation of adhesion molecules to enhance barrier function, the regulation of intestinal stem cell function, cellular homeostasis of other divalent cations, the regulation of drug metabolizing enzymes, and anti‐inflammatory effects. © 2021 The Author. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Sylvia Christakos
- Department of Microbiology, Biochemistry and Molecular Genetics Rutgers, the State University of New Jersey, New Jersey Medical School Newark NJ USA
| |
Collapse
|
9
|
Verlinden L, Carmeliet G. Integrated View on the Role of Vitamin D Actions on Bone and Growth Plate Homeostasis. JBMR Plus 2021; 5:e10577. [PMID: 34950832 PMCID: PMC8674772 DOI: 10.1002/jbm4.10577] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 10/22/2021] [Accepted: 10/31/2021] [Indexed: 12/12/2022] Open
Abstract
1,25(OH)2D3, the biologically active form of vitamin D3, is a major regulator of mineral and bone homeostasis and exerts its actions through binding to the vitamin D receptor (VDR), a ligand‐activated transcription factor that can directly modulate gene expression in vitamin D‐target tissues such as the intestine, kidney, and bone. Inactivating VDR mutations or vitamin D deficiency during development results in rickets, hypocalcemia, secondary hyperparathyroidism, and hypophosphatemia, pointing to the critical role of 1,25(OH)2D3‐induced signaling in the maintenance of mineral homeostasis and skeletal health. 1,25(OH)2D3 is a potent stimulator of VDR‐mediated intestinal calcium absorption, thus increasing the availability of calcium required for proper bone mineralization. However, when intestinal calcium absorption is impaired, renal calcium reabsorption is increased and calcium is mobilized from the bone to preserve normocalcemia. Multiple cell types within bone express the VDR, thereby allowing 1,25(OH)2D3 to directly affect bone homeostasis. In this review, we will discuss different transgenic mouse models with either Vdr deletion or overexpression in chondrocytes, osteoblasts, osteocytes, or osteoclasts to delineate the direct effects of 1,25(OH)2D3 on bone homeostasis. We will address the bone cell type–specific effects of 1,25(OH)2D3 in conditions of a positive calcium balance, where the amount of (re)absorbed calcium equals or exceeds fecal and renal calcium losses, as well as during a negative calcium balance, due to selective Vdr knockdown in the intestine or triggered by a low calcium diet. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Lieve Verlinden
- Clinical and Experimental Endocrinology, Department of Chronic Diseases and Metabolism KU Leuven Leuven Belgium
| | - Geert Carmeliet
- Clinical and Experimental Endocrinology, Department of Chronic Diseases and Metabolism KU Leuven Leuven Belgium
| |
Collapse
|
10
|
Effects of Extracellular Osteoanabolic Agents on the Endogenous Response of Osteoblastic Cells. Cells 2021; 10:cells10092383. [PMID: 34572032 PMCID: PMC8471159 DOI: 10.3390/cells10092383] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/31/2021] [Accepted: 09/07/2021] [Indexed: 12/27/2022] Open
Abstract
The complex multidimensional skeletal organization can adapt its structure in accordance with external contexts, demonstrating excellent self-renewal capacity. Thus, optimal extracellular environmental properties are critical for bone regeneration and inextricably linked to the mechanical and biological states of bone. It is interesting to note that the microstructure of bone depends not only on genetic determinants (which control the bone remodeling loop through autocrine and paracrine signals) but also, more importantly, on the continuous response of cells to external mechanical cues. In particular, bone cells sense mechanical signals such as shear, tensile, loading and vibration, and once activated, they react by regulating bone anabolism. Although several specific surrounding conditions needed for osteoblast cells to specifically augment bone formation have been empirically discovered, most of the underlying biomechanical cellular processes underneath remain largely unknown. Nevertheless, exogenous stimuli of endogenous osteogenesis can be applied to promote the mineral apposition rate, bone formation, bone mass and bone strength, as well as expediting fracture repair and bone regeneration. The following review summarizes the latest studies related to the proliferation and differentiation of osteoblastic cells, enhanced by mechanical forces or supplemental signaling factors (such as trace metals, nutraceuticals, vitamins and exosomes), providing a thorough overview of the exogenous osteogenic agents which can be exploited to modulate and influence the mechanically induced anabolism of bone. Furthermore, this review aims to discuss the emerging role of extracellular stimuli in skeletal metabolism as well as their potential roles and provide new perspectives for the treatment of bone disorders.
Collapse
|
11
|
Arnold A, Dennison E, Kovacs CS, Mannstadt M, Rizzoli R, Brandi ML, Clarke B, Thakker RV. Hormonal regulation of biomineralization. Nat Rev Endocrinol 2021; 17:261-275. [PMID: 33727709 DOI: 10.1038/s41574-021-00477-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/29/2021] [Indexed: 01/31/2023]
Abstract
Biomineralization is the process by which organisms produce mineralized tissues. This crucial process makes possible the rigidity and flexibility that the skeleton needs for ambulation and protection of vital organs, and the hardness that teeth require to tear and grind food. The skeleton also serves as a source of mineral in times of short supply, and the intestines absorb and the kidneys reclaim or excrete minerals as needed. This Review focuses on physiological and pathological aspects of the hormonal regulation of biomineralization. We discuss the roles of calcium and inorganic phosphate, dietary intake of minerals and the delicate balance between activators and inhibitors of mineralization. We also highlight the importance of tight regulation of serum concentrations of calcium and phosphate, and the major regulators of biomineralization: parathyroid hormone (PTH), the vitamin D system, vitamin K, fibroblast growth factor 23 (FGF23) and phosphatase enzymes. Finally, we summarize how developmental stresses in the fetus and neonate, and in the mother during pregnancy and lactation, invoke alternative hormonal regulatory pathways to control mineral delivery, skeletal metabolism and biomineralization.
Collapse
Affiliation(s)
- Andrew Arnold
- Division of Endocrinology & Metabolism and Center for Molecular Oncology, University of Connecticut School of Medicine, Farmington, CT, USA.
| | - Elaine Dennison
- MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK
| | - Christopher S Kovacs
- Faculty of Medicine - Endocrinology, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Michael Mannstadt
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - René Rizzoli
- Division of Bone Diseases, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
| | - Maria Luisa Brandi
- Department of Biochemical, Experimental and Clinical Sciences, University of Florence, Florence, Italy
| | - Bart Clarke
- Mayo Clinic Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Rochester, MN, USA
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| |
Collapse
|
12
|
Lin EL, Gottesman GS, McAlister WH, Bijanki VN, Mack KE, Griffin DM, Mumm S, Whyte MP. Healing of vitamin D deficiency rickets complicating hypophosphatasia suggests a role beyond circulating mineral sufficiency for vitamin D in musculoskeletal health. Bone 2020; 136:115322. [PMID: 32200022 DOI: 10.1016/j.bone.2020.115322] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/10/2020] [Accepted: 03/16/2020] [Indexed: 12/17/2022]
Abstract
Hypophosphatasia (HPP) is the metabolic bone disease caused by loss-of-function mutation(s) of the ALPL gene that encodes the cell-surface tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP). In HPP, extracellular accumulation of inorganic pyrophosphate (PPi), a TNSALP natural substrate and inhibitor of biomineralization, often leads to rickets or osteomalacia despite normal or sometimes elevated circulating levels of calcium (Ca) and inorganic phosphate (Pi). We report an infant girl with vitamin D deficiency rickets subsequently healed by cholecalciferol administration alone before receiving TNSALP-replacement therapy for accompanying HPP. Throughout her clinical course, circulating Ca and Pi levels were normal or elevated. At presentation with failure-to-thrive at age six months, radiographs revealed severe rickets and serum 25(OH)D was 8 ng/mL (Nl, 30-100), yet low ALP activity 55 U/L (Nl, 124-341), normal Ca 9.3 mg/dL (Nl, 8.5-10.1) and Pi 6.4 mg/dL (Nl, 3.5-7.0), and low-normal parathyroid hormone 21 pg/mL (Nl, 14-72) were instead consistent with HPP. At age nine months, after 1000 IU of cholecalciferol orally each day for six weeks, serum 25(OH)D was 86 ng/mL, strength markedly better, and radiographs documented significant improvement of rickets. At age 18 months, with fully healed vitamin D deficiency rickets, findings of underlying HPP included a waddling gait and Gower sign, metaphyseal "tongues" of radiolucency, elevated serum pyridoxal 5'-phosphate 121 ng/mL (Nl, 2-33), and bi-allelic ALPL missense mutations. Then, nearly complete restoration of strength and radiographic healing of her remaining skeletal disease from HPP occurred during asfotase alfa enzyme replacement treatment. At no time, including presentation, were circulating Ca or Pi levels compromised. Instead, and in keeping with HPP, high-normal or elevated serum Ca and Pi concentrations were consistently documented. Thus, our findings suggest some role for vitamin D in musculoskeletal health beyond assuring circulating mineral sufficiency.
Collapse
Affiliation(s)
- Elizabeth L Lin
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children, St. Louis, MO 63110, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Gary S Gottesman
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children, St. Louis, MO 63110, USA.
| | - William H McAlister
- Mallinckrodt Institute of Radiology, Washington University School of Medicine at St. Louis Children's Hospital, St. Louis, MO 63110, USA.
| | - Vinieth N Bijanki
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children, St. Louis, MO 63110, USA.
| | - Karen E Mack
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children, St. Louis, MO 63110, USA.
| | - Donna M Griffin
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children, St. Louis, MO 63110, USA.
| | - Steven Mumm
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children, St. Louis, MO 63110, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children, St. Louis, MO 63110, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
| |
Collapse
|
13
|
Meyer MB, Pike JW. Mechanistic homeostasis of vitamin D metabolism in the kidney through reciprocal modulation of Cyp27b1 and Cyp24a1 expression. J Steroid Biochem Mol Biol 2020; 196:105500. [PMID: 31629064 PMCID: PMC6954286 DOI: 10.1016/j.jsbmb.2019.105500] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/07/2019] [Accepted: 10/14/2019] [Indexed: 01/08/2023]
Abstract
Cyp27b1 and Cyp24a1 are reciprocally regulated in the kidney by the key hormones PTH, FGF23, and 1,25(OH)2D3. Our recent genomic studies in mice identified a complex kidney-specific enhancer module located within the introns of adjacent Mettl1 (M1) and Mettl21b (M21) genes that mediate basal and PTH induction of Cyp27b1 as well as suppression by FGF23 and 1,25(OH)2D3. Gross deletion of these segments in mice has severe consequences on skeletal health, and directly affects Cyp27b1 expression in the kidney. Deletion of both M1 and M21 submodules together fully eliminates basal Cyp27b1 expression in the kidney, leading to a systemic and skeletal phenotype similar to that of the Cyp27b1-KO mouse due to depletion of 1,25(OH)2D3 and high PTH. Cyp24a1 levels in the double KO mouse were low due to compensatory regulation by elevated PTH and reduced FGF23. However, expression of Cyp27b1 and retention of its regulation by inflammation (LPS) in the NRTCs remained unperturbed. Dietary normalization of calcium, phosphate, PTH, and FGF23 rescues this aberrant phenotype and normalizes the skeletal issues. Cyp24a1 is controlled by its own unique enhancers for 1,25(OH)2D3, FGF23, and PTH. We were also able to eliminate these activities in mice. Collectively, the hormone-mediated enhancer regulation of both Cyp27b1 and Cyp24a1 in the kidney is responsible for the circulating levels of 1,25(OH)2D3 in the blood which in turn primarily affects calcium and phosphate regulation. Importantly, we can now manipulate this system with our enhancer deletion animal models to study 1,25(OH)2D3 production in non-renal target cells and tissues not only in disease, where it is known to affect the immune system, but also in healthy individuals. Here we will review our studies that have defined a finely balanced homeostatic control mechanism employed by PTH and FGF23 with catastrophic toxicity protection from 1,25(OH)2D3 in the genomic regulation of vitamin D metabolism and its accompanied control of mineral maintenance.
Collapse
Affiliation(s)
- Mark B Meyer
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
| | - J Wesley Pike
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| |
Collapse
|
14
|
Christakos S, Li S, De La Cruz J, Shroyer NF, Criss ZK, Verzi MP, Fleet JC. Vitamin D and the intestine: Review and update. J Steroid Biochem Mol Biol 2020; 196:105501. [PMID: 31655181 PMCID: PMC6954280 DOI: 10.1016/j.jsbmb.2019.105501] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 10/04/2019] [Accepted: 10/14/2019] [Indexed: 12/11/2022]
Abstract
The central role of vitamin D in calcium homeostasis is to increase calcium absorption from the intestine. This article describes the early work that served as the foundation for the initial model of vitamin D mediated calcium absorption. In addition, other research related to the role of vitamin D in the intestine, including those which have challenged the traditional model and the crucial role of specific calcium transport proteins, are reviewed. More recent work identifying novel targets of 1,25(OH)2D3 action in the intestine and highlighting the importance of 1,25(OH)2D3 action across the proximal/distal and crypt/villus axes in the intestine is summarized.
Collapse
Affiliation(s)
- Sylvia Christakos
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ 07103, USA.
| | - Shanshan Li
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ 07103, USA
| | - Jessica De La Cruz
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, NJ 07103, USA
| | - Noah F Shroyer
- Integrative Molecular and Biomedical Sciences Graduate Program, Division of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zachary K Criss
- Integrative Molecular and Biomedical Sciences Graduate Program, Division of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael P Verzi
- Department of Genetics, Rutgers University, New Brunswick, NJ 08854, USA
| | - James C Fleet
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| |
Collapse
|
15
|
Erem S, Atfi A, Razzaque MS. Anabolic effects of vitamin D and magnesium in aging bone. J Steroid Biochem Mol Biol 2019; 193:105400. [PMID: 31175968 DOI: 10.1016/j.jsbmb.2019.105400] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/25/2019] [Accepted: 06/05/2019] [Indexed: 02/08/2023]
Abstract
Decreased bone mass and an increased risk of bone fractures become more common with age. This condition is often associated with osteoporosis and is caused by an imbalance of bone resorption and new bone formation. Lifestyle factors that affect the risk of osteoporosis include alcohol, diet, hormones, physical activity, and smoking. Calcium and vitamin D are particularly important for the age-related loss of bone density and skeletal muscle mass, but other minerals, such as magnesium, also have an important role. Here, we summarize how optimal magnesium and vitamin D balance improve health outcomes in the elderly, the role of magnesium and vitamin D on bone formation, and the implications of widespread deficiency of these factors in the United States and worldwide, particularly in the elderly population.
Collapse
Affiliation(s)
- Sarah Erem
- Department of Pathology, Saba University School of Medicine, Saba, Dutch Caribbean, Netherlands
| | - Azeddine Atfi
- Department of Pathology, Virginia Commonwealth University, Richmond, VA, USA
| | - Mohammed S Razzaque
- Department of Pathology, Saba University School of Medicine, Saba, Dutch Caribbean, Netherlands; College of Advancing & Professional Studies (CAPS), University of Massachusetts Boston (UMB), Boston, MA, USA; Department of Pathology, Lake Erie College of Osteopathic Medicine, Erie, PA, USA.
| |
Collapse
|
16
|
Bouillon R, Marcocci C, Carmeliet G, Bikle D, White JH, Dawson-Hughes B, Lips P, Munns CF, Lazaretti-Castro M, Giustina A, Bilezikian J. Skeletal and Extraskeletal Actions of Vitamin D: Current Evidence and Outstanding Questions. Endocr Rev 2019; 40:1109-1151. [PMID: 30321335 PMCID: PMC6626501 DOI: 10.1210/er.2018-00126] [Citation(s) in RCA: 544] [Impact Index Per Article: 108.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/17/2018] [Indexed: 02/06/2023]
Abstract
The etiology of endemic rickets was discovered a century ago. Vitamin D is the precursor of 25-hydroxyvitamin D and other metabolites, including 1,25(OH)2D, the ligand for the vitamin D receptor (VDR). The effects of the vitamin D endocrine system on bone and its growth plate are primarily indirect and mediated by its effect on intestinal calcium transport and serum calcium and phosphate homeostasis. Rickets and osteomalacia can be prevented by daily supplements of 400 IU of vitamin D. Vitamin D deficiency (serum 25-hydroxyvitamin D <50 nmol/L) accelerates bone turnover, bone loss, and osteoporotic fractures. These risks can be reduced by 800 IU of vitamin D together with an appropriate calcium intake, given to institutionalized or vitamin D-deficient elderly subjects. VDR and vitamin D metabolic enzymes are widely expressed. Numerous genetic, molecular, cellular, and animal studies strongly suggest that vitamin D signaling has many extraskeletal effects. These include regulation of cell proliferation, immune and muscle function, skin differentiation, and reproduction, as well as vascular and metabolic properties. From observational studies in human subjects, poor vitamin D status is associated with nearly all diseases predicted by these extraskeletal actions. Results of randomized controlled trials and Mendelian randomization studies are supportive of vitamin D supplementation in reducing the incidence of some diseases, but, globally, conclusions are mixed. These findings point to a need for continued ongoing and future basic and clinical studies to better define whether vitamin D status can be optimized to improve many aspects of human health. Vitamin D deficiency enhances the risk of osteoporotic fractures and is associated with many diseases. We review what is established and what is plausible regarding the health effects of vitamin D.
Collapse
Affiliation(s)
- Roger Bouillon
- Laboratory of Clinical and Experimental Endocrinology, Department of Chronic Diseases, Metabolism and Ageing, KU Leuven, Belgium
| | - Claudio Marcocci
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Geert Carmeliet
- Laboratory of Clinical and Experimental Endocrinology, Department of Chronic Diseases, Metabolism and Ageing, KU Leuven, Belgium
| | - Daniel Bikle
- Veterans Affairs Medical Center and University of California San Francisco, San Francisco, California
| | - John H White
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Bess Dawson-Hughes
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts
| | - Paul Lips
- Department of Internal Medicine, Endocrine Section, VU University Medical Center, HV Amsterdam, Netherlands
| | - Craig F Munns
- Children’s Hospital at Westmead, Sydney, New South Wales, Australia
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Marise Lazaretti-Castro
- Division of Endocrinology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Andrea Giustina
- Chair of Endocrinology, Vita-Salute San Raffaele University, Milan, Italy
| | - John Bilezikian
- Department of Endocrinology, Columbia University College of Physicians and Surgeons, New York, New York
| |
Collapse
|
17
|
Meyer MB, Benkusky NA, Kaufmann M, Lee SM, Redfield RR, Jones G, Pike JW. Targeted genomic deletions identify diverse enhancer functions and generate a kidney-specific, endocrine-deficient Cyp27b1 pseudo-null mouse. J Biol Chem 2019; 294:9518-9535. [PMID: 31053643 DOI: 10.1074/jbc.ra119.008760] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 04/26/2019] [Indexed: 12/19/2022] Open
Abstract
Vitamin D3 is terminally bioactivated in the kidney to 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) via cytochrome P450 family 27 subfamily B member 1 (CYP27B1), whose gene is regulated by parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and 1,25(OH)2D3 Our recent genomic studies in the mouse have revealed a complex kidney-specific enhancer module within the introns of adjacent methyltransferase-like 1 (Mettl1) and Mettl21b that mediate basal and PTH-induced expression of Cyp27b1 and FGF23- and 1,25(OH)2D3-mediated repression. Gross deletion of these segments in mice has severe effects on Cyp27b1 regulation and skeletal phenotype but does not affect Cyp27b1 expression in nonrenal target cells (NRTCs). Here, we report a bimodal activity in the Mettl1 intronic enhancer with components responsible for PTH-mediated Cyp27b1 induction and 1,25(OH)2D3-mediated repression and additional activities, including FGF23 repression, within the Mettl21b enhancers. Deletion of both submodules eliminated basal Cyp27b1 expression and regulation in the kidney, leading to systemic and skeletal phenotypes similar to those of Cyp27b1-null mice. However, basal expression and lipopolysaccharide-induced regulation of Cyp27b1 in NRTCs was unperturbed. Importantly, dietary normalization of calcium, phosphate, PTH, and FGF23 rescued the skeletal phenotype of this mutant mouse, creating an ideal in vivo model to study nonrenal 1,25(OH)2D3 production in health and disease. Finally, we confirmed a conserved chromatin landscape in human kidney that is similar to that in mouse. These findings define a finely balanced homeostatic mechanism involving PTH and FGF23 together with protection from 1,25(OH)2D3 toxicity that is responsible for both adaptive vitamin D metabolism and mineral regulation.
Collapse
Affiliation(s)
- Mark B Meyer
- From the Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706,
| | - Nancy A Benkusky
- From the Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Martin Kaufmann
- the Departments of Biomedical and Molecular Sciences and.,Surgery, Queen's University, Kingston, Ontario K7L 3N6, Canada, and
| | - Seong Min Lee
- From the Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Robert R Redfield
- the Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706
| | | | - J Wesley Pike
- From the Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| |
Collapse
|
18
|
Ryan BA, Alhani K, Sellars KB, Kirby BJ, St-Arnaud R, Kaufmann M, Jones G, Kovacs CS. Mineral Homeostasis in Murine Fetuses Is Sensitive to Maternal Calcitriol but Not to Absence of Fetal Calcitriol. J Bone Miner Res 2019; 34:669-680. [PMID: 30508318 DOI: 10.1002/jbmr.3642] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 11/13/2018] [Accepted: 11/14/2018] [Indexed: 12/14/2022]
Abstract
Vitamin D receptor (VDR) null fetuses have normal serum minerals, parathyroid hormone (PTH), skeletal morphology, and mineralization but increased serum calcitriol, placental calcium transport, and placental expression of Pthrp, Trpv6, and (as reported in this study) Pdia3. We examined Cyp27b1 null fetal mice, which do not make calcitriol, to determine if loss of calcitriol has the same consequences as loss of VDR. Cyp27b1 null and wild-type (WT) females were mated to Cyp27b1+/- males, which generated Cyp27b1 null and Cyp27b1+/- fetuses from Cyp27b1 null mothers, and Cyp27b1+/- and WT fetuses from WT mothers. Cyp27b1 null fetuses had undetectable calcitriol but normal serum calcium and phosphorus, PTH, fibroblast growth factor 23 (FGF23), skeletal mineral content, tibial lengths and morphology, placental calcium transport, and expression of Trpv6 and Pthrp; conversely, placental Pdia3 was downregulated. However, although Cyp27b1+/- and null fetuses of Cyp27b1 null mothers were indistinguishable, they had higher serum and amniotic fluid calcium, lower amniotic fluid phosphorus, lower FGF23, and higher 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D than in WT and Cyp27b1+/- fetuses of WT mothers. In summary, loss of fetal calcitriol did not alter mineral or bone homeostasis, but Cyp27b1 null mothers altered mineral homeostasis in their fetuses independent of fetal genotype. Cyp27b1 null fetuses differ from Vdr null fetuses, possibly through high levels of calcitriol acting on Pdia3 in Vdr nulls to upregulate placental calcium transport and expression of Trpv6 and Pthrp. In conclusion, maternal calcitriol influences fetal mineral metabolism, whereas loss of fetal calcitriol does not. © 2018 American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Brittany A Ryan
- Faculty of Medicine-Endocrinology, Memorial University of Newfoundland, St. John's, Canada
| | - Kamal Alhani
- Faculty of Medicine-Endocrinology, Memorial University of Newfoundland, St. John's, Canada
| | - K Berit Sellars
- Faculty of Medicine-Endocrinology, Memorial University of Newfoundland, St. John's, Canada
| | - Beth J Kirby
- Faculty of Medicine-Endocrinology, Memorial University of Newfoundland, St. John's, Canada
| | - René St-Arnaud
- Shriners Hospitals for Children-Canada and McGill University, Montréal, Canada
| | | | | | - Christopher S Kovacs
- Faculty of Medicine-Endocrinology, Memorial University of Newfoundland, St. John's, Canada
| |
Collapse
|
19
|
Reinke DC, Starczak Y, Kogawa M, Barratt KR, Morris HA, Anderson PH, Atkins GJ. Evidence for altered osteoclastogenesis in splenocyte cultures from VDR knockout mice. J Steroid Biochem Mol Biol 2018; 177:96-102. [PMID: 28765041 DOI: 10.1016/j.jsbmb.2017.07.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 07/24/2017] [Accepted: 07/26/2017] [Indexed: 12/22/2022]
Abstract
The indirect action of 1α,25(OH)2-vitamin-D3 (1,25D) on the osteoclast through stromal signalling is well established. The role of vitamin D in osteoclasts through direct 1,25D-VDR signalling is less well known. We showed previously that local 1,25D synthesis in osteoclasts modified osteoclastogenesis and osteoclastic resorptive activity. In this study, we hypothesised that osteoclasts lacking VDR expression would display an enhanced resorptive capacity due to the loss of 1,25D signalling. Splenocytes were cultured under osteoclast-differentiating conditions from mice with global deletion of the Vdr gene (VDRKO) and this was compared with age-matched wild-type littermate controls (WT). In VDRKO cultures, osteoclastogenesis was reduced, as indicated by fewer TRAP-positive multinucleated cells at all time points measured (p<0.05) compared to WT levels. However, VDRKO osteoclasts demonstrated greater resorption on a per cell basis than their WT counterparts. VDRKO cultures expressed greatly increased c-Fos mRNA compared to WT. In addition, the ratio of expression of the pro-apoptotic gene Bax to the pro-survival gene Bcl-2 was decreased in VDRKO cultures, implying that these osteoclasts may survive longer than WT osteoclasts. Our data indicate abnormal osteoclastogenesis due to the absence of Vdr expression, consistent with direct effects of vitamin D signalling being important for regulating the maturation and resorptive activities of osteoclasts.
Collapse
Affiliation(s)
- Daniel C Reinke
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic & Trauma Research, University of Adelaide, Australia
| | - Yolandi Starczak
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic & Trauma Research, University of Adelaide, Australia; School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5005, Australia
| | - Masakazu Kogawa
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic & Trauma Research, University of Adelaide, Australia
| | - Kate R Barratt
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5005, Australia
| | - Howard A Morris
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5005, Australia
| | - Paul H Anderson
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5005, Australia
| | - Gerald J Atkins
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic & Trauma Research, University of Adelaide, Australia.
| |
Collapse
|
20
|
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.
Collapse
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
| |
Collapse
|
21
|
|
22
|
Gillies BR, Ryan BA, Tonkin BA, Poulton IJ, Ma Y, Kirby BJ, St-Arnaud R, Sims NA, Kovacs CS. Absence of Calcitriol Causes Increased Lactational Bone Loss and Lower Milk Calcium but Does Not Impair Post-lactation Bone Recovery in Cyp27b1 Null Mice. J Bone Miner Res 2018; 33:16-26. [PMID: 28686309 DOI: 10.1002/jbmr.3217] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 06/26/2017] [Accepted: 07/06/2017] [Indexed: 12/14/2022]
Abstract
We hypothesized that adaptation to calcium supply demands of pregnancy and lactation do not require calcitriol. Adult Cyp27b1 null mice lack calcitriol and have hypocalcemia, hypophosphatemia, and rickets. We studied wild-type (WT) and null sister pairs raised on a calcium-, phosphorus-, and lactose-enriched "rescue" diet that prevents hypocalcemia and rickets. Bone mineral content (BMC) increased >30% in pregnant nulls, declined 30% during lactation, and increased 30% by 4 weeks post-weaning. WT showed less marked changes. Micro-CT revealed loss of trabecular bone and recovery in both genotypes. In lactating nulls, femoral cortical thickness declined >30%, whereas endocortical perimeter increased; both recovered to baseline after weaning; there were no such changes in WT. Histomorphometry revealed a profound increase in osteoid surface and thickness in lactating nulls, which recovered after weaning. By three-point bend test, nulls had a >50% decline in ultimate load to failure that recovered after weaning. Although nulls showed bone loss during lactation, their milk calcium content was 30% lower compared with WT. Serum parathyroid hormone (PTH) was markedly elevated in nulls at baseline, reduced substantially in pregnancy, but increased again during lactation and remained high post-weaning. In summary, pregnant Cyp27b1 nulls gained BMC with reduced secondary hyperparathyroidism, implying increased intestinal calcium delivery. Lactating nulls lost more bone mass and strength than WT, accompanied by increased osteoid, reduced milk calcium, and worsened secondary hyperparathyroidism. This implies suboptimal intestinal calcium absorption. Post-weaning, bone mass and strength recovered to baseline, whereas BMC exceeded baseline by 40%. In conclusion, calcitriol-independent mechanisms regulate intestinal calcium absorption and trabecular bone metabolism during pregnancy and post-weaning but not during lactation; calcitriol may protect cortical bone during lactation. © 2017 American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Brittany R Gillies
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada
| | - Brittany A Ryan
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada
| | - Brett A Tonkin
- St. Vincent's Institute of Medical Research and the Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Melbourne, Australia
| | - Ingrid J Poulton
- St. Vincent's Institute of Medical Research and the Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Melbourne, Australia
| | - Yue Ma
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada
| | - Beth J Kirby
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada
| | - René St-Arnaud
- Shriners Hospitals for Children and Faculty of Medicine, McGill University, Montreal, Canada
| | - Natalie A Sims
- St. Vincent's Institute of Medical Research and the Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Melbourne, Australia
| | | |
Collapse
|
23
|
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: 41] [Impact Index Per Article: 5.9] [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.
Collapse
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
| |
Collapse
|
24
|
Lindner J, Rausch S, Treptow S, Geldmeyer-Hilt K, Krause T, St-Arnaud R, Arabian A, Radbruch A, Hartmann S, Worm M, Heine G. Endogenous Calcitriol Synthesis Controls the Humoral IgE Response in Mice. THE JOURNAL OF IMMUNOLOGY 2017; 199:3952-3958. [PMID: 29109124 DOI: 10.4049/jimmunol.1602080] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 10/11/2017] [Indexed: 12/16/2022]
Abstract
The vitamin D receptor participates in the control of IgE class-switch recombination in B cells. The physiologic vitamin D receptor agonist, 1,25(OH)2D3 (calcitriol), is synthesized by the essential enzyme 25-hydroxyvitamin D3-1α-hydroxylase (CYP27B1), which can be expressed by activated immune cells. The role of endogenous calcitriol synthesis for the regulation of IgE has not been proven. In this study, we investigated IgE-responses in Cyp27b1-knockout (KO) mice following sensitization to OVA or intestinal infection with Heligmosomoides polygyrus Specific Igs and plasmablasts were determined by ELISA and ELISpot, Cyp27b1 expression was measured by quantitative PCR. The data show elevated specific IgE and IgG1 concentrations in the blood of OVA-sensitized Cyp27b1-KO mice compared with wild-type littermates (+898 and +219%). Accordingly, more OVA-specific IgG1-secreting cells are present in spleen and fewer in the bone marrow of Cyp27b1-KO mice. Ag-specific mechanisms are suggested as the leucopoiesis is in general unchanged and activated murine B and T lymphocytes express Cyp27b1 Accordingly, elevated specific IgE concentrations in the blood of sensitized T cell-specific Cyp27b1-KO mice support a lymphocyte-driven mechanism. In an independent IgE-inducing model, i.e., intestinal infection with H. polygyrus, we validated the increase of total and specific IgE concentrations of Cyp27b1-KO compared with wild-type mice, but not those of IgG1 or IgA. We conclude that endogenous calcitriol has an impact on the regulation of IgE in vivo. Our data provide genetic evidence supporting previous preclinical and clinical findings and suggest that vitamin D deficiency not only promotes bone diseases but also type I sensitization.
Collapse
Affiliation(s)
- Juliane Lindner
- Klinik für Dermatologie, Venerologie und Allergologie, Allergie-Centrum-Charité, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, D-10117 Berlin, Germany
| | - Sebastian Rausch
- Institut für Immunologie-Fachbereich Veterinärmedizin, Freie Universität, D-14163 Berlin, Germany
| | - Sandra Treptow
- Klinik für Dermatologie, Venerologie und Allergologie, Allergie-Centrum-Charité, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, D-10117 Berlin, Germany
| | - Kerstin Geldmeyer-Hilt
- Klinik für Dermatologie, Venerologie und Allergologie, Allergie-Centrum-Charité, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, D-10117 Berlin, Germany
| | - Tina Krause
- Klinik für Dermatologie, Venerologie und Allergologie, Allergie-Centrum-Charité, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, D-10117 Berlin, Germany
| | - René St-Arnaud
- Research Centre, Shriners Hospitals for Children-Canada, Montreal, Quebec H4A 0A9, Canada; and
| | - Alice Arabian
- Research Centre, Shriners Hospitals for Children-Canada, Montreal, Quebec H4A 0A9, Canada; and
| | | | - Susanne Hartmann
- Institut für Immunologie-Fachbereich Veterinärmedizin, Freie Universität, D-14163 Berlin, Germany
| | - Margitta Worm
- Klinik für Dermatologie, Venerologie und Allergologie, Allergie-Centrum-Charité, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, D-10117 Berlin, Germany;
| | - Guido Heine
- Klinik für Dermatologie, Venerologie und Allergologie, Allergie-Centrum-Charité, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, D-10117 Berlin, Germany;
| |
Collapse
|
25
|
Abstract
PURPOSE OF REVIEW In addition to the actions of the endocrine hormone, 1alpha,25-dihydroxyvitamin D (1,25(OH)2D) in stimulating intestinal calcium absorption, the regulation of bone mineral metabolism by 1,25(OH)2D is also considered an important contributor to calcium homeostasis. However, recent evidence suggest that 1,25(OH)2D acting either via endocrine or autocrine pathways plays varied roles in bone, which suggests that vitamin D contributes to the maintenance of bone mineral in addition to its catabolic roles. This review highlights the contrasting evidence for the direct action for vitamin D metabolism and activity in bone. RECENT FINDINGS Numerous cells within bone express vitamin D receptor (VDR), synthesise and catabolise 1,25(OH)2D via 25-hydroxyvitamin D 1alpha-hydroxylase (CYP27B1), and 25-hydroxyvitamin D 24-hydroxylase (CYP24A1) enzymes, respectively. Recent evidence suggests that all three genes are required to regulate processes of bone resorption, mineralization and fracture repair. The actions of vitamin D in bone appear to negatively or positively regulate bone mineral depending on the physiological and pathological circumstances, suggesting that vitamin D plays pleiotropic roles in bone.
Collapse
Affiliation(s)
- Paul H Anderson
- Musculoskeletal Biology Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, 5001, Australia.
| |
Collapse
|
26
|
Christakos S, Veldurthy V, Patel N, Wei R. Intestinal Regulation of Calcium: Vitamin D and Bone Physiology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1033:3-12. [PMID: 29101648 DOI: 10.1007/978-3-319-66653-2_1] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The principal function of vitamin D in the maintenance of calcium homeostasis is to increase intestinal calcium absorption. This conclusion was made from studies in vitamin D receptor (VDR) null mice which showed that rickets and osteomalacia were prevented when VDR null mice were fed a rescue diet that included high calcium, indicating that the skeletal abnormalities of the VDR null mice are primarily the result of impaired intestinal calcium absorption. Although vitamin D is critical for controlling intestinal calcium absorption, the mechanisms involved have remained incomplete. This chapter reviews studies, including studies in genetically modified mice, that have provided new insight and have challenged the traditional model of VDR-mediated calcium absorption.
Collapse
Affiliation(s)
- Sylvia Christakos
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers the State University of New Jersey, New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103, USA.
| | - Vaishali Veldurthy
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers the State University of New Jersey, New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103, USA
| | - Nishant Patel
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers the State University of New Jersey, New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103, USA
| | - Ran Wei
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers the State University of New Jersey, New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103, USA
| |
Collapse
|
27
|
Hirota Y, Nakagawa K, Mimatsu S, Sawada N, Sakaki T, Kubodera N, Kamao M, Tsugawa N, Suhara Y, Okano T. Nongenomic effects of 1α,25-dihydroxyvitamin D 3 on cartilage formation deduced from comparisons between Cyp27b1 and Vdr knockout mice. Biochem Biophys Res Commun 2017; 483:359-365. [DOI: 10.1016/j.bbrc.2016.12.139] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 12/21/2016] [Indexed: 10/20/2022]
|
28
|
van der Meijden K, Buskermolen J, van Essen HW, Schuurman T, Steegenga WT, Brouwer-Brolsma EM, Langenbach GEJ, van Ruijven LJ, den Heijer M, Lips P, Bravenboer N. Long-term vitamin D deficiency in older adult C57BL/6 mice does not affect bone structure, remodeling and mineralization. J Steroid Biochem Mol Biol 2016; 164:344-352. [PMID: 26361014 DOI: 10.1016/j.jsbmb.2015.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 09/03/2015] [Indexed: 12/22/2022]
Abstract
Animal models show that vitamin D deficiency may have severe consequences for skeletal health. However, most studies have been performed in young rodents for a relatively short period, while in older adult rodents the effects of long-term vitamin D deficiency on skeletal health have not been extensively studied. Therefore, the first aim of this study was to determine the effects of long-term vitamin D deficiency on bone structure, remodeling and mineralization in bones from older adult mice. The second aim was to determine the effects of long-term vitamin D deficiency on mRNA levels of genes involved in vitamin D metabolism in bones from older adult mice. Ten months old male C57BL/6 mice were fed a diet containing 0.5% calcium, 0.2% phosphate and 0 (n=8) or 1 (n=9) IU vitamin D3/gram for 14 months. At an age of 24 months, mice were sacrificed for histomorphometric and micro-computed tomography (micro-CT) analysis of humeri as well as analysis of CYP27B1, CYP24 and VDR mRNA levels in tibiae and kidneys using RT-qPCR. Plasma samples, obtained at 17 and 24 months of age, were used for measurements of 25-hydroxyvitamin D (25(OH)D) (all samples), phosphate and parathyroid hormone (PTH) (terminal samples) concentrations. At the age of 17 and 24 months, mean plasma 25(OH)D concentrations were below the detection limit (<4nmol/L) in mice receiving vitamin D deficient diets. Plasma phosphate and PTH concentrations did not differ between both groups. Micro-CT and histomorphometric analysis of bone mineral density, structure and remodeling did not reveal differences between control and vitamin D deficient mice. Long-term vitamin D deficiency did also not affect CYP27B1 mRNA levels in tibiae, while CYP24 mRNA levels in tibiae were below the detection threshold in both groups. VDR mRNA levels in tibiae from vitamin D deficient mice were 0.7 fold lower than those in control mice. In conclusion, long-term vitamin D deficiency in older adult C57BL/6 mice, accompanied by normal plasma PTH and phosphate concentrations, does not affect bone structure, remodeling and mineralization. In bone, expression levels of CYP27B1 are also not affected by long-term vitamin D deficiency in older adult C57BL/6 mice. Our results suggest that mice at old age have a low or absent response to vitamin D deficiency probably due to factors such as a decreased bone formation rate or a reduced response of bone cells to 25(OH)D and 1,25(OH)2D. Older adult mice may therefore be less useful for the study of the effects of vitamin D deficiency on bone health in older people.
Collapse
Affiliation(s)
- K van der Meijden
- Department of Endocrinology/Internal Medicine, VU University Medical Center, MOVE Research Institute, Amsterdam, The Netherlands
| | - J Buskermolen
- Department of Clinical Chemistry, VU University Medical Center, Research Institute MOVE, Amsterdam, The Netherlands
| | - H W van Essen
- Department of Clinical Chemistry, VU University Medical Center, Research Institute MOVE, Amsterdam, The Netherlands
| | - T Schuurman
- Department of Animal Sciences, Animal Nutrition Group, Wageningen University, Wageningen, The Netherlands
| | - W T Steegenga
- Division of Human Nutrition, Nutrition and Health Group/Nutrition and Epidemiology Group/Nutrition, Metabolism and Genomics Group, Wageningen University, Wageningen, The Netherlands
| | - E M Brouwer-Brolsma
- Division of Human Nutrition, Nutrition and Health Group/Nutrition and Epidemiology Group/Nutrition, Metabolism and Genomics Group, Wageningen University, Wageningen, The Netherlands
| | - G E J Langenbach
- Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute, Amsterdam, The Netherlands
| | - L J van Ruijven
- Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute, Amsterdam, The Netherlands
| | - M den Heijer
- Department of Endocrinology/Internal Medicine, VU University Medical Center, MOVE Research Institute, Amsterdam, The Netherlands
| | - P Lips
- Department of Endocrinology/Internal Medicine, VU University Medical Center, MOVE Research Institute, Amsterdam, The Netherlands
| | - N Bravenboer
- Department of Clinical Chemistry, VU University Medical Center, Research Institute MOVE, Amsterdam, The Netherlands.
| |
Collapse
|
29
|
Kovacs CS. Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery. Physiol Rev 2016; 96:449-547. [PMID: 26887676 DOI: 10.1152/physrev.00027.2015] [Citation(s) in RCA: 251] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ∼30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.
Collapse
Affiliation(s)
- Christopher S Kovacs
- Faculty of Medicine-Endocrinology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| |
Collapse
|
30
|
Bai X, Miao D, Xiao S, Qiu D, St-Arnaud R, Petkovich M, Gupta A, Goltzman D, Karaplis AC. CYP24 inhibition as a therapeutic target in FGF23-mediated renal phosphate wasting disorders. J Clin Invest 2016; 126:667-80. [PMID: 26784541 DOI: 10.1172/jci81928] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 11/25/2015] [Indexed: 12/13/2022] Open
Abstract
CYP24A1 (hereafter referred to as CYP24) enzymatic activity is pivotal in the inactivation of vitamin D metabolites. Basal renal and extrarenal CYP24 is usually low but is highly induced by its substrate 1,25-dihydroxyvitamin D. Unbalanced high and/or long-lasting CYP24 expression has been proposed to underlie diseases like chronic kidney disease, cancers, and psoriasis that otherwise should favorably respond to supplemental vitamin D. Using genetically modified mice, we have shown that renal phosphate wasting hypophosphatemic states arising from high levels of fibroblast growth factor 23 (FGF23) are also associated with increased renal Cyp24 expression, suggesting that elevated CYP24 activity is pivotal to the pathophysiology of these disorders. We therefore crossed 2 mouse strains, each with distinct etiology for high levels of circulating FGF23, onto a Cyp24-null background. Specifically, we evaluated Cyp24 deficiency in Hyp mice, the murine homolog of X-linked dominant hypophosphatemic rickets, and transgenic mice that overexpress a mutant FGF23 (FGF23R176Q) that is associated with the autosomal dominant form of hypophosphatemic rickets. Loss of Cyp24 in these murine models of human disease resulted in near-complete recovery of rachitic/osteomalacic bony abnormalities in the absence of any improvement in the serum biochemical profile. Moreover, treatment of Hyp and FGF23R1760-transgenic mice with the CYP24 inhibitor CTA102 also ameliorated their rachitic bones. Our results link CYP24 activity to the pathophysiology of FGF23-dependent renal phosphate wasting states and implicate pharmacologic CYP24 inhibition as a therapeutic adjunct for their treatment.
Collapse
|
31
|
Carmeliet G, Dermauw V, Bouillon R. Vitamin D signaling in calcium and bone homeostasis: a delicate balance. Best Pract Res Clin Endocrinol Metab 2015; 29:621-31. [PMID: 26303088 DOI: 10.1016/j.beem.2015.06.001] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Loss-of-function mutations in genes involved in the vitamin D/vitamin D receptor system have clearly evidenced its critical role for mineral and skeletal homeostasis. Adequate levels of 1,25-dihydroxyvitamin D [1,25(OH)2D], the active form of vitamin D are therefore required and depend on sufficient sunlight exposure or dietary intake. Intestinal calcium absorption is a primary target of 1,25(OH)2D action and this pathway indirectly promotes calcium incorporation in bone. Severe vitamin D deficiency may thus decrease bone quality and leads to osteomalacia, whereas less severe deficiency increases the risk of osteoporosis and bone fractures. On the other hand, high vitamin D levels together with low dietary calcium intake will increase bone resorption and decrease bone mineralization in order to maintain normal serum calcium levels. Appropriate dietary calcium intake and sufficient serum vitamin D levels are thus important for skeletal health. Dosing of calcium and vitamin D supplements is still debated and requires further investigation.
Collapse
Affiliation(s)
- Geert Carmeliet
- Laboratory of Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Veronique Dermauw
- Laboratory of Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Roger Bouillon
- Laboratory of Clinical and Experimental Endocrinology, Department of Clinical and Experimental Medicine, KU Leuven, 3000 Leuven, Belgium.
| |
Collapse
|
32
|
Girgis CM, Baldock PA, Downes M. Vitamin D, muscle and bone: Integrating effects in development, aging and injury. Mol Cell Endocrinol 2015; 410:3-10. [PMID: 25837735 DOI: 10.1016/j.mce.2015.03.020] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 03/24/2015] [Accepted: 03/24/2015] [Indexed: 12/14/2022]
Abstract
Beyond the established effects of muscle loading on bone, a complex network of hormones and growth factors integrates these adjacent tissues. One such hormone, vitamin D, exerts broad-ranging effects in muscle and bone calcium handling, differentiation and development. Vitamin D also modulates muscle and bone-derived hormones, potentially facilitating cross-talk between these tissues. In the clinical setting, vitamin D deficiency or mutations of the vitamin D receptor result in generalized atrophy of muscle and bone, suggesting coordinated effects of vitamin D at these sites. In this review, we discuss emerging evidence that vitamin D exerts specific effects throughout the life of the musculoskeletal system - in development, aging and injury. From this holistic viewpoint, we offer new insights into an old debate: whether vitamin D's effects in the musculoskeletal system are direct via local VDR signals or indirect via its systemic effects in calcium and phosphate homeostasis.
Collapse
Affiliation(s)
- Christian M Girgis
- Westmead Millennium Institute for Medical Research, Sydney, NSW, Australia; Faculty of Medicine, University of Sydney, Sydney, NSW, Australia; Garvan Institute of Medical Research, Sydney, NSW, Australia.
| | - Paul A Baldock
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | | |
Collapse
|
33
|
Lee SM, Riley EM, Meyer MB, Benkusky NA, Plum LA, DeLuca HF, Pike JW. 1,25-Dihydroxyvitamin D3 Controls a Cohort of Vitamin D Receptor Target Genes in the Proximal Intestine That Is Enriched for Calcium-regulating Components. J Biol Chem 2015; 290:18199-18215. [PMID: 26041780 DOI: 10.1074/jbc.m115.665794] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Indexed: 12/15/2022] Open
Abstract
1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) plays an integral role in calcium homeostasis in higher organisms through its actions in the intestine, kidney, and skeleton. Interestingly, although several intestinal genes are known to play a contributory role in calcium homeostasis, the entire caste of key components remains to be identified. To examine this issue, Cyp27b1 null mice on either a normal or a high calcium/phosphate-containing rescue diet were treated with vehicle or 1,25(OH)2D3 and evaluated 6 h later. RNA samples from the duodena were then subjected to RNA sequence analysis, and the data were analyzed bioinformatically. 1,25(OH)2D3 altered expression of large collections of genes in animals under either dietary condition. 45 genes were found common to both 1,25(OH)2D3-treated groups and were composed of genes previously linked to intestinal calcium uptake, including S100g, Trpv6, Atp2b1, and Cldn2 as well as others. An additional distinct network of 56 genes was regulated exclusively by diet. We then conducted a ChIP sequence analysis of binding sites for the vitamin D receptor (VDR) across the proximal intestine in vitamin D-sufficient normal mice treated with vehicle or 1,25(OH)2D3. The residual VDR cistrome was composed of 4617 sites, which was increased almost 4-fold following hormone treatment. Interestingly, the majority of the genes regulated by 1,25(OH)2D3 in each diet group as well as those found in common in both groups contained frequent VDR sites that likely regulated their expression. This study revealed a global network of genes in the intestine that both represent direct targets of vitamin D action in mice and are involved in calcium absorption.
Collapse
Affiliation(s)
- Seong Min Lee
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Erin M Riley
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Mark B Meyer
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Nancy A Benkusky
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Lori A Plum
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Hector F DeLuca
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - J Wesley Pike
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706.
| |
Collapse
|
34
|
Goltzman D. Inferences from genetically modified mouse models on the skeletal actions of vitamin D. J Steroid Biochem Mol Biol 2015; 148:219-24. [PMID: 25237033 DOI: 10.1016/j.jsbmb.2014.09.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 08/26/2014] [Accepted: 09/11/2014] [Indexed: 02/04/2023]
Abstract
Vitamin D has pleiotropic extra-skeletal effects which have been noted in mouse models of deletion of either the 25-hydroxy vitamin D 1α-hydroxylase enzyme, cyp27b1 (1OHase(-/-) mice) or of the vitamin D receptor (Vdr(-/-) mice); these may be preventable or reversible by either restoring normal signaling of the 1,25(OH)2D/VDR system, or in some cases by restoring normal mineral homeostasis. However, effects on skeletal and mineral homeostasis are clearly the major phenotype observed in humans with loss-of-function mutations in either CYP27B1 or VDR. In mouse phenocopies of these human disorders, correction of hypocalcemia and hypophosphatemia reduce elevated circulating parathyroid hormone concentrations and normalize impaired bone mineralization, but restoration of normal 1,25(OH)2D/VDR signaling may be required for optimal bone formation. Induction of high endogenous 1,25(OH)2D concentrations in genetically modified mouse models may cause increased bone resorption and decreased mineralization. Transgenic Vdr overexpression and conditional Vdr deletion in cells of the osteoblastic lineage have also provided insights into the stages of osteoblast differentiation which may mediate these actions. These anabolic and catabolic effects of the 1,25(OH)2D system on bone may therefore be a function of both the ambient concentration of circulating 1,25(OH)2D and the stage of differentiation of the osteoblast. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.
Collapse
Affiliation(s)
- D Goltzman
- Calcium Research Laboratory, Departments of Medicine and Physiology, McGill University Health Centre, Montreal, Quebec H3A 1A1, Canada.
| |
Collapse
|
35
|
Kovacs CS. Bone development and mineral homeostasis in the fetus and neonate: roles of the calciotropic and phosphotropic hormones. Physiol Rev 2014; 94:1143-218. [PMID: 25287862 DOI: 10.1152/physrev.00014.2014] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mineral and bone metabolism are regulated differently in utero compared with the adult. The fetal kidneys, intestines, and skeleton are not dominant sources of mineral supply for the fetus. Instead, the placenta meets the fetal need for mineral by actively transporting calcium, phosphorus, and magnesium from the maternal circulation. These minerals are maintained in the fetal circulation at higher concentrations than in the mother and normal adult, and such high levels appear necessary for the developing skeleton to accrete a normal amount of mineral by term. Parathyroid hormone (PTH) and calcitriol circulate at low concentrations in the fetal circulation. Fetal bone development and the regulation of serum minerals are critically dependent on PTH and PTH-related protein, but not vitamin D/calcitriol, fibroblast growth factor-23, calcitonin, or the sex steroids. After birth, the serum calcium falls and phosphorus rises before gradually reaching adult values over the subsequent 24-48 h. The intestines are the main source of mineral for the neonate, while the kidneys reabsorb mineral, and bone turnover contributes mineral to the circulation. This switch in the regulation of mineral homeostasis is triggered by loss of the placenta and a postnatal fall in serum calcium, and is followed in sequence by a rise in PTH and then an increase in calcitriol. Intestinal calcium absorption is initially a passive process facilitated by lactose, but later becomes active and calcitriol-dependent. However, calcitriol's role can be bypassed by increasing the calcium content of the diet, or by parenteral administration of calcium.
Collapse
Affiliation(s)
- Christopher S Kovacs
- Faculty of Medicine-Endocrinology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| |
Collapse
|
36
|
Goltzman D, Hendy GN, White JH. Vitamin D and its receptor during late development. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:171-80. [PMID: 24939836 DOI: 10.1016/j.bbagrm.2014.05.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 05/06/2014] [Accepted: 05/27/2014] [Indexed: 12/26/2022]
Abstract
Expression of the vitamin D receptor (VDR) is widespread but may vary depending on the developmental stage of the animal, and therefore may differentially influence phenotypic function. Thus, the major role of the 1,25-dihydroxyvitamin D [1,25(OH)2D]/VDR system is to regulate mineral and skeletal homeostasis, although mainly after birth. Post-natally, under conditions of low dietary calcium, the 1,25(OH)2D/VDR system enhances intestinal transcellular transport of calcium and possibly paracellular calcium entry by regulating genes that are critical for these functions. This process, by providing adequate calcium, is essential for normal development of the skeletal growth plate and mineralization of bone. Furthermore, blood calcium and phosphorus homeostasis is maintained by an interplay between feedback loops of the 1,25(OH)2D/VDR system with parathyroid hormone and with fibroblast-growth factor (FGF) 23 respectively. The 1,25(OH)2D/VDR system can also modulate the expression of genes involved in both bone formation and resorption post-natally. Ligand independent activity of the VDR normally influences mammalian hair cycling after birth by potentiating Wnt and bone morphogenetic protein (BMP) signaling. Nevertheless ligand bound VDR may also modulate epidermal cell proliferation/differentiation by regulating the balance in function of c-MYC and its antagonist the transcriptional repressor MAD1/MXD1 in skin epithelia. The 1,25(OH)2D/VDR system can also modulate innate immune cells and promote a more tolerogenic immunological status and may therefore influence inflammation and the development of autoimmunity; whether this impacts the fetus is uncertain. This article is part of a Special Issue entitled: Nuclear receptors in animal development.
Collapse
Affiliation(s)
- D Goltzman
- Department of Medicine, McGill University, Montreal, QC H3A1A1, Canada; Department of Physiology, McGill University, Montreal, QC H3A1A1, Canada
| | - G N Hendy
- Department of Medicine, McGill University, Montreal, QC H3A1A1, Canada; Department of Physiology, McGill University, Montreal, QC H3A1A1, Canada
| | - J H White
- Department of Medicine, McGill University, Montreal, QC H3A1A1, Canada; Department of Physiology, McGill University, Montreal, QC H3A1A1, Canada
| |
Collapse
|
37
|
Abstract
Teeth are mineralized organs composed of three unique hard tissues, enamel, dentin, and cementum, and supported by the surrounding alveolar bone. Although odontogenesis differs from osteogenesis in several respects, tooth mineralization is susceptible to similar developmental failures as bone. Here we discuss conditions fitting under the umbrella of rickets, which traditionally referred to skeletal disease associated with vitamin D deficiency but has been more recently expanded to include newly identified factors involved in endocrine regulation of vitamin D, phosphate, and calcium, including phosphate-regulating endopeptidase homolog, X-linked, fibroblast growth factor 23, and dentin matrix protein 1. Systemic mineral metabolism intersects with local regulation of mineralization, and factors including tissue nonspecific alkaline phosphatase are necessary for proper mineralization, where rickets can result from loss of activity of tissue nonspecific alkaline phosphatase. Individuals suffering from rickets often bear the additional burden of a defective dentition, and transgenic mouse models have aided in understanding the nature and mechanisms involved in tooth defects, which may or may not parallel rachitic bone defects. This report reviews dental effects of the range of rachitic disorders, including discussion of etiologies of hereditary forms of rickets, a survey of resulting bone and tooth mineralization disorders, and a discussion of mechanisms, known and hypothesized, involved in the observed dental pathologies. Descriptions of human pathology are augmented by analysis of transgenic mouse models, and new interpretations are brought to bear on questions of how teeth are affected under conditions of rickets. In short, the rachitic tooth will be revealed.
Collapse
Affiliation(s)
- Brian L Foster
- National Institute for Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | | | | |
Collapse
|
38
|
Alshbool FZ, Alarcon C, Wergedal J, Mohan S. A high-calcium diet failed to rescue an osteopenia phenotype in claudin-18 knockout mice. Physiol Rep 2014; 2:e00200. [PMID: 24744879 PMCID: PMC3967683 DOI: 10.1002/phy2.200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 12/03/2013] [Indexed: 12/14/2022] Open
Abstract
We have recently demonstrated that mice with disruption of claudin‐18 (Cldn‐18) gene exhibited osteopenia due to increased bone resorption (BR). In this study, we found that gastric pH was significantly higher in Cldn‐18 knockout (KO) mice compared to heterozygous control mice at 10 weeks of age. To test the possibility that the increased BR in the Cldn‐18 KO mice fed a normal‐Ca diet is a consequence of decreased Ca absorption caused by increased stomach pH, we subjected KO and control mice to a normal‐Ca and high‐Ca diet at birth. Serum Ca levels were significantly lower in Cldn‐18 KO mice compared to control mice at a normal‐Ca diet but not at high‐Ca diet. Dual energy X‐ray absorptiometry revealed that a high‐Ca diet significantly increased lumbar bone mineral density (BMD), but had no effect on femur/tibia BMD in both Cldn‐18 KO and control mice compared to a normal‐Ca diet. While a high‐Ca diet did not affect volumetric BMD, trabecular, and cortical parameters of the lumbar vertebra (LV) as measured by μCT, the size of the LV did increase, in both genotypes due to reduced BR. Comparison of the skeletal phenotype of high‐Ca Cldn‐18 KO and control mice revealed that an osteopenia phenotype seen at a normal‐Ca diet was still maintained at different skeletal sites in the KO mice till 10 weeks of age. In conclusion, our findings suggest that increased BR is likely caused by direct effects of a lack of Cldn‐18 on osteoclasts rather than gastric pH changes. In this study, we examined if calcium deficiency caused by low‐gastric acidity was the cause of osteopenia phenotype observed in claudin‐18 (Cldn‐18) knockout (KO) mice. Our findings that high‐calcium diet did not rescue the osteopenia phenotype in Cldn‐18 KO mice suggest that increased bone resorption is likely caused by direct effects of a lack of Cldn‐18 on osteoclasts rather than gastric pH changes.
Collapse
Affiliation(s)
- Fatima Z Alshbool
- Musculoskeletal Disease Center, Jerry L Pettis VA Medical Center, Loma Linda, 92357, California ; Department of Pharmacology, Loma Linda University, Loma Linda, 92354, California
| | - Catrina Alarcon
- Musculoskeletal Disease Center, Jerry L Pettis VA Medical Center, Loma Linda, 92357, California
| | - Jon Wergedal
- Musculoskeletal Disease Center, Jerry L Pettis VA Medical Center, Loma Linda, 92357, California ; Department of Medicine, Loma Linda University, Loma Linda, 92354, California
| | - Subburaman Mohan
- Musculoskeletal Disease Center, Jerry L Pettis VA Medical Center, Loma Linda, 92357, California ; Department of Medicine, Loma Linda University, Loma Linda, 92354, California ; Department of Biochemistry, Loma Linda University, Loma Linda, 92354, California ; Department of Physiology, Loma Linda University, Loma Linda, 92354, California
| |
Collapse
|
39
|
Masuyama R. Role of local vitamin D signaling and cellular calcium transport system in bone homeostasis. J Bone Miner Metab 2014; 32:1-9. [PMID: 24213217 DOI: 10.1007/s00774-013-0508-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 08/07/2013] [Indexed: 12/14/2022]
Abstract
Mouse genetic studies have demonstrated that the 1,25-dihydroxyvitamin D [1,25(OH)2D] endocrine system is required for calcium (Ca(2+)) and bone homeostasis. These studies reported severe hypocalcemia and impaired bone mineralization associated with rickets in mutant mice. Specific phenotypes of these mice with an engineered deletion of 1,25(OH)2D cell signaling resemble the features observed in humans with the same congenital disease or severe 1,25(OH)2D deficiency. Decreased active intestinal Ca(2+) absorption because of reduced expression of epithelial Ca(2+) channels is a crucial mechanism that contributes to the major phenotypes observed in the mutant mice. The importance of intestinal Ca(2+) absorption supported by 1,25(OH)2D-mediated transport was further emphasized by the observation that Ca(2+) supplementation rescues hypocalcemia and restores bone mineralization in both patients and mice lacking 1,25(OH)2D signaling. This observation questions the direct role of 1,25(OH)2D signaling in bone tissue. Studies regarding tissue-specific manipulation of 1,25(OH)2D function have provided a consensus on this issue by demonstrating a direct action of 1,25(OH)2D on cells in bone tissue through bone metabolism and mineral homeostasis. In addition, movement of Ca(2+) from the bone as a result of osteoclastic bone resorption also provides a large Ca(2+) supply in Ca(2+) homeostasis; however, the system controlling Ca(2+) homeostasis in osteoclasts has not been fully identified. Transient receptor potential vanilloid (TRPV) 4 mediates Ca(2+) influx during the late stage of osteoclast differentiation, thereby regulating the Ca(2+) signaling essential for cellular events during osteoclast differentiation; however, the system-modifying effect of TRPV4 activity should be determined. Furthermore, it remains unknown how local Ca(2+) metabolism participates in systemic Ca(2+) homeostasis through bone remodeling. New insights are therefore required to understand this issue.
Collapse
Affiliation(s)
- Ritsuko Masuyama
- Department of Molecular Bone Biology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, 852-8588, Japan,
| |
Collapse
|
40
|
Abstract
Calcium has recently been shown to regulate fibroblast growth factor 23 (FGF-23), a bone-derived phosphate and vitamin D-regulating hormone. To better understand the regulation of FGF-23 by calcium, phosphorus, 1,25 dihydroxyvitamin D3 [1,25(OH)2D], and PTH, we examined FGF-23 expression under basal conditions and in response to PTH, doxercalciferol, or high-calcium diet treatment in Gcm2(-/-) and Cyp27b1(-/-) mutant mice. Gcm2(-/-) mice exhibited low serum PTH and 1,25(OH)2D concentrations, hypocalcemia, and hyperphosphatemia, whereas Cyp27b1(-/-) mice had high PTH, undetectable 1,25(OH)2D, hypocalcemia, and hypophosphatemia. Serum FGF-23 levels were decreased in both mutant models. Doxercalciferol administration increased serum FGF-23 levels in both mutant models. PTH administration to Gcm2(-/-) mice also increased serum FGF-23 levels, in association with an increase in both 1,25(OH)2D and calcium concentrations. Multiple regression analysis of pooled data indicated that changes in FGF-23 were positively correlated with serum calcium and 1,25(OH)2D but not related to changes in serum phosphate concentrations. A high-calcium diet also increased serum FGF-23 concentrations in Cyp27b1(-/-) mice in the absence of 1,25(OH)2D and in Gcm2(-/-) mice with low PTH. The addition of calcium to the culture media also stimulated FGF-23 message expression in MC3T3-E1 osteoblasts. In addition, FGF-23 promoter activity in cultured osteoblasts was inhibited by the L-calcium-channel inhibitor nifedipine and stimulated by calcium ionophores. The effects of chronic low calcium to prevent 1,25(OH)2D and PTH stimulation of FGF-23 in these mutant mouse models suggest that suppression of FGF-23 plays an important physiological adaptive response to hypocalcemia.
Collapse
Affiliation(s)
- Valentin David
- MD, Coleman College of Medicine Building, Suite B226, University of Tennessee Health Science Center, 956 Court Avenue, Memphis Tennessee 38163.
| | | | | | | | | | | |
Collapse
|
41
|
Vitamin D activities and metabolic bone disease. Clin Chim Acta 2013; 425:148-52. [DOI: 10.1016/j.cca.2013.07.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Accepted: 07/23/2013] [Indexed: 12/16/2022]
|
42
|
Christakos S, Seth T, Hirsch J, Porta A, Moulas A, Dhawan P. Vitamin D Biology Revealed Through the Study of Knockout and Transgenic Mouse Models. Annu Rev Nutr 2013; 33:71-85. [DOI: 10.1146/annurev-nutr-071812-161249] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Sylvia Christakos
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103;
| | - Tanya Seth
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103;
| | - Jennifer Hirsch
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103;
| | - Angela Porta
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103;
| | - Anargyros Moulas
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103;
| | - Puneet Dhawan
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103;
| |
Collapse
|
43
|
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.
Collapse
Affiliation(s)
- Glenville Jones
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | | | | |
Collapse
|
44
|
Kopic S, Geibel JP. Gastric acid, calcium absorption, and their impact on bone health. Physiol Rev 2013; 93:189-268. [PMID: 23303909 DOI: 10.1152/physrev.00015.2012] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Calcium balance is essential for a multitude of physiological processes, ranging from cell signaling to maintenance of bone health. Adequate intestinal absorption of calcium is a major factor for maintaining systemic calcium homeostasis. Recent observations indicate that a reduction of gastric acidity may impair effective calcium uptake through the intestine. This article reviews the physiology of gastric acid secretion, intestinal calcium absorption, and their respective neuroendocrine regulation and explores the physiological basis of a potential link between these individual systems.
Collapse
Affiliation(s)
- Sascha Kopic
- Department of Surgery and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| | | |
Collapse
|
45
|
Abstract
All cells comprising the skeleton-chondrocytes, osteoblasts, and osteoclasts-contain both the vitamin D receptor and the enzyme CYP27B1 required for producing the active metabolite of vitamin D, 1,25 dihydroxyvitamin D. Direct effects of 25 hydroxyvitamin D and 1,25 dihydroxyvitamin D on these bone cells have been demonstrated. However, the major skeletal manifestations of vitamin D deficiency or mutations in the vitamin D receptor and CYP27B1, namely rickets and osteomalacia, can be corrected by increasing the intestinal absorption of calcium and phosphate, indicating the importance of indirect effects. On the other hand, these dietary manipulations do not reverse defects in osteoblast or osteoclast function that lead to osteopenic bone. This review discusses the relative importance of the direct versus indirect actions of vitamin D on bone, and provides guidelines for the clinical use of vitamin D to prevent/treat bone loss and fractures.
Collapse
Affiliation(s)
- Daniel D Bikle
- University of California, San Francisco, San Francisco, CA, USA.
| |
Collapse
|
46
|
Anderson PH, Turner AG, Morris HA. Vitamin D actions to regulate calcium and skeletal homeostasis. Clin Biochem 2012; 45:880-6. [PMID: 22414785 DOI: 10.1016/j.clinbiochem.2012.02.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Revised: 02/22/2012] [Accepted: 02/24/2012] [Indexed: 12/22/2022]
Abstract
The endocrine action of plasma 1,25-dihydroxyvitamin D plays a key role in the regulation of plasma calcium and phosphate homeostasis with activities on the intestine, kidney and bone. A current, controversial question is whether vitamin D exerts direct actions on bone cells to regulate bone mineral homeostasis. Results from clinical, rodent model and in vitro studies on human bone cells provide an impressive body of data to support this proposal particularly at the level of serum 25-hydroxyvitamin D status. Each of the major bone cell types is capable of metabolising vitamin D to the active metabolite, 1,25-dihydroxyvitamin D. Thus under conditions when bone tissue synthesis of 1,25-dihydroxyvitamin D is optimal, vitamin D activity enhances bone mineral status. Dietary calcium and phosphate intakes are the critical environmental cues together with vitamin D status to determine whether 1,25-dihydroxyvitamin D exerts an anabolic or catabolic action on bone mineral status.
Collapse
Affiliation(s)
- Paul H Anderson
- School of Pharmacy and Medical Sciences, University of South Australia, and Chemical Pathology Directorate, SA Pathology, Frome Road, Adelaide 5000 SA, Australia
| | | | | |
Collapse
|
47
|
Anderson PH, Atkins GJ, Turner AG, Kogawa M, Findlay DM, Morris HA. Vitamin D metabolism within bone cells: effects on bone structure and strength. Mol Cell Endocrinol 2011; 347:42-7. [PMID: 21664230 DOI: 10.1016/j.mce.2011.05.024] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 05/04/2011] [Accepted: 05/09/2011] [Indexed: 11/16/2022]
Abstract
The endocrine activity of 1,25-dihydroxyvitamin D (1,25(OH)(2)D(3)) contributes to maintaining plasma calcium and phosphate homeostasis through actions on the intestine, kidney and bone. A significant body of evidence has been published over the last 10 years indicating that all major bone cells have the capacity to metabolise 25-hydroxyvitamin D (25(OH)D(3)) to 1,25(OH)(2)D(3), which in turn exerts autocrine/paracrine actions to regulate bone cell proliferation and maturation as well as bone mineralisation and resorption. In vivo and in vitro studies indicate that these autocrine/paracrine activities of 1,25(OH)(2)D(3) in bone tissue contribute to maintaining bone mineral homeostasis and enhancing skeletal health.
Collapse
Affiliation(s)
- Paul H Anderson
- Endocrine Bone Research Laboratory, Chemical Pathology, SA Pathology, Adelaide, SA 5000, Australia
| | | | | | | | | | | |
Collapse
|
48
|
St-Arnaud R, Naja RP. Vitamin D metabolism, cartilage and bone fracture repair. Mol Cell Endocrinol 2011; 347:48-54. [PMID: 21664253 DOI: 10.1016/j.mce.2011.05.018] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 04/26/2011] [Accepted: 05/02/2011] [Indexed: 12/19/2022]
Abstract
The 1,25-(OH)(2)D metabolite mediates the endocrine actions of vitamin D by regulating in the small intestine the expression of target genes that play a critical role in intestinal calcium absorption. The major role of the vitamin D hormone on bone is indirect and mediated through its endocrine function on mineral homeostasis. However, genetic manipulation of the expression of Cyp27b1 or the VDR in chondrocytes strongly support a direct role for locally synthesized 1,25(OH)(2)D, acting through the VDR, in vascular invasion and osteoclastogenesis during endochondral bone development. Cells from the growth plate respond to the 24,25-(OH)(2)D and 1,25-(OH)(2)D metabolites in a cell maturation-dependent manner and the effects of 1,25-(OH)(2)D are thought to be mediated through binding to the membrane-associated receptor PDIA3 (protein disulfide isomerase associated 3). The physiological relevance of membrane-mediated 1,25-(OH)(2)D signaling is emerging and is discussed. Finally, preliminary results suggest that mice deficient for Cyp24a1 exhibit a delay in bone fracture healing and support a role for 24,25-(OH)(2)D in mammalian fracture repair.
Collapse
Affiliation(s)
- René St-Arnaud
- Genetics Unit, Shriners Hospital for Children, Montreal, Quebec, Canada H3G 1A6.
| | | |
Collapse
|
49
|
Lee CSD, Chen J, Wang Y, Williams JK, Ranly DM, Schwartz Z, Boyan BD. Coordinated tether formation in anatomically distinct mice growth centers is dependent on a functional vitamin D receptor and is tightly linked to three-dimensional tissue morphology. Bone 2011; 49:419-27. [PMID: 21601024 DOI: 10.1016/j.bone.2011.05.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 04/27/2011] [Accepted: 05/04/2011] [Indexed: 11/17/2022]
Abstract
Bone bridges linking the epiphysis and metaphysis termed "tethers" have been found in the femoral growth plates of C57Bl/6 mice and are disrupted when the vitamin D receptor (VDR) is ablated. It is unknown if tethers are found in other growth centers, if they are regulated in a comparable manner, or if they have a functional role in skeletal development or stability. To address this, distal femoral growth plates (GPs) and spheno-occipital synchondroses (SOSs) of wild-type C57Bl/6 mice from 2 to 15 weeks of age were analyzed using μCT scans. The GPs and SOSs of VDR+/+ and VDR-/- mice fed regular or rescue diets to restore mineral homeostasis until 10 weeks of age were also scanned. Tethers in GPs and SOSs both thickened and accumulated in number as these growth centers decreased in size. Ablating the VDR made GPs and SOSs rachitic and nearly eliminated tether formation. Rescue diets restored the volume of both growth centers but only partially restored growth center thickness and tether formation, suggesting that lα,25-dihydroxy vitamin D(3) partially regulates tether formation in these growth centers via its receptor. In VDR+/+ mice 2-15 weeks in age, growth center thickness was inversely correlated to animal weight whereas tether phenotype (tether volume/growth center volume, tether number/mm, tether width, tether spacing) was significantly related to animal weight. In both 2-15 week old VDR+/+ and 10 week old VDR+/+ and VDR-/- mice on normal and rescue diets, tether phenotype (tether number/mm, tether spacing) had strikingly similar relationships to growth center thickness. These results show that tethers are present in growth centers in different anatomic and undergo developmental changes in a comparable manner; in both sites, VDR-regulated tether formation is strongly linked to growth center morphology; and tether formation is associated with body weight, suggesting a role in maintaining growth plate stability during growth.
Collapse
Affiliation(s)
- Christopher S D Lee
- Wallace H. Coulter Department of Biomedical Engineering and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332-0363, USA
| | | | | | | | | | | | | |
Collapse
|
50
|
St-Arnaud R, Arabian A, Akhouayri O, Knutson JC, Strugnell SA. Differential effects of oral doxercalciferol (Hectorol) or paricalcitol (Zemplar) in the Cyp27b1-null mouse model of uremia. Nephron Clin Pract 2011; 119:e67-74. [PMID: 21849802 DOI: 10.1159/000329663] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Accepted: 05/20/2011] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND/AIMS Kidney disease patients experience declining calcitriol levels and develop secondary hyperparathyroidism (SHPT). Animal models of uremia based on 5/6 nephrectomy (NTX) do not consistently reproduce this calcitriol deficiency. We developed an animal model, the NTX Cyp27b1-null mouse, which completely lacks endogenous calcitriol, and examined the suitability of this model for evaluation of treatment with vitamin D analogs in uremia. METHODS NTX was performed at 2 months of age. One week post-NTX, animals were treated for 4 weeks with vehicle; doxercalciferol at 30, 100 or 300 pg/g body weight (b.w.); or paricalcitol at 100, 300 or 1,000 pg/g b.w. by gavage 3 times per week. RESULTS Serum blood urea nitrogen and creatinine were elevated. Vehicle-treated NTX null mice had hypocalcemia and SHPT. Doxercalciferol at 100 or 300 pg/g b.w. normalized serum calcium and parathyroid hormone (PTH) levels. Paricalcitol at 300 or 1,000 pg/g normalized serum calcium, but PTH levels remained elevated. Osteomalacia was corrected by 100 pg/g b.w. of doxercalciferol or 1,000 pg/g b.w. of paricalcitol. The highest dose of doxercalciferol, but not of paricalcitol, significantly reduced osteitis fibrosa. CONCLUSION Our results reveal the differential efficacy of doxercalciferol and paricalcitol in this novel animal model incorporating both calcitriol deficiency and renal insufficiency.
Collapse
Affiliation(s)
- René St-Arnaud
- Genetics Unit, Shriners Hospital for Children, Montreal, Qué., Canada
| | | | | | | | | |
Collapse
|