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Adragao T, Ferreira A, Frazao JM, Papoila AL, Pinto I, Monier-Faugere MC, Malluche HH. Higher mineralized bone volume is associated with a lower plain X-Ray vascular calcification score in hemodialysis patients. PLoS One 2017; 12:e0179868. [PMID: 28686736 PMCID: PMC5501435 DOI: 10.1371/journal.pone.0179868] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 06/04/2017] [Indexed: 11/19/2022] Open
Abstract
Background and objectives In dialysis patients, there is an increasing evidence that altered bone metabolism is associated with cardiovascular calcifications. The main objective of this study was to analyse, in hemodialysis patients, the relationships between bone turnover, mineralization and volume, evaluated in bone biopsies, with a plain X-ray vascular calcification score. Design, setting, participants and measurements In a cross-sectional study, bone biopsies and evaluation of vascular calcifications were performed in fifty hemodialysis patients. Cancellous bone volume, mineralized bone volume, osteoid volume, activation frequency, bone formation rate/bone surface, osteoid thickness and mineralization lag time were determined by histomorphometry. Vascular calcifications were assessed by the simple vascular calcification score (SVCS) in plain X-Ray of pelvis and hands and, for comparison, by the Agatston score in Multi-Slice Computed Tomography (MSCT). Results SVCS≥3 was present in 20 patients (40%). Low and high bone turnover were present in 54% and 38% of patients, respectively. Low bone volume was present in 20% of patients. In multivariable analysis, higher age (p = 0.015) and longer hemodialysis duration (p = 0.017) were associated with SVCS≥3. Contrary to cancellous bone volume, the addition to this model of mineralized bone volume (OR = 0.863; 95%CI: 0.766, 0.971; p = 0.015), improved the performance of the model. For each increase of 1% in mineralized bone volume there was a 13.7% decrease in the odds of having SVCS≥3 (p = 0.015). An Agatston score>400 was observed in 80% of the patients with a SVCS≥3 versus 4% of patients with a SVCS<3, (p<0.001). Conclusion Higher mineralized bone volume was associated with a lower plain X-ray vascular calcification. This study corroborates the hypothesis of the existence of a link between bone and vessel and reinforces the clinical utility of this simple and inexpensive vascular calcification score in dialysis patients.
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Affiliation(s)
- Teresa Adragao
- Nephrology Department, Santa Cruz Hospital, Lisbon, Portugal
- * E-mail:
| | - Anibal Ferreira
- Nephrology Department, Curry Cabral Hospital, Lisbon, Portugal
| | - Joao M. Frazao
- Nephrology Department, S Joao Hospital, Medical School and Nephrology Research and Development Unit, University of Porto, Porto, Portugal
| | - Ana Luisa Papoila
- CEAUL, CEDOC, Nova Medical School/FCM, New University, Lisbon, Portugal
| | | | - Marie-Claude Monier-Faugere
- Division of Nephrology, Bone and Mineral Metabolism, University of Kentucky, Lexington, KY, United States of America
| | - Hartmut H. Malluche
- Division of Nephrology, Bone and Mineral Metabolism, University of Kentucky, Lexington, KY, United States of America
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Pogorielov M, Husak E, Solodivnik A, Zhdanov S. Magnesium-based biodegradable alloys: Degradation, application, and alloying elements. Interv Med Appl Sci 2017; 9:27-38. [PMID: 28932493 PMCID: PMC5598119 DOI: 10.1556/1646.9.2017.1.04] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In recent years, the paradigm about the metal with improved corrosion resistance for application in surgery and orthopedy was broken. The new class of biodegradable metal emerges as an alternative for biomedical implants. These metals corrode gradually with an appropriate host response and release of corrosion products. And it is absolutely necessary to use essential metals metabolized by hosting organism with local and general nontoxic effect. Magnesium serves this aim best; it plays the essential role in body metabolism and should be completely excreted within a few days after degradation. This review summarizes data from Mg discovery and its first experimental and clinical application of modern concept of Mg alloy development. We focused on biodegradable metal application in general surgery and orthopedic practice and showed the advantages and disadvantages Mg alloys offer. We focused on methods of in vitro and in vivo investigation of degradable Mg alloys and correlation between these methods. Based on the observed data, a better way for new alloy pre-clinical investigation is suggested. This review analyzes possible alloying elements that improve corrosion rate, mechanical properties, and gives the appropriate host response.
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Affiliation(s)
| | - Eugenia Husak
- Medical Institute, Sumy State University, Sumy, Ukraine
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Mohammed SG, Arjona FJ, Latta F, Bindels RJM, Roepman R, Hoenderop JGJ. Fluid shear stress increases transepithelial transport of Ca
2+
in ciliated distal convoluted and connecting tubule cells. FASEB J 2017; 31:1796-1806. [DOI: 10.1096/fj.201600687rrr] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 01/03/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Sami G. Mohammed
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Francisco J. Arjona
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Femke Latta
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - René J. M. Bindels
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Ronald Roepman
- Department of Human GeneticsRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Joost G. J. Hoenderop
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
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54
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Bishay RH, Ganda K, Seibel MJ. Long-term iron polymaltose infusions associated with hypophosphataemic osteomalacia: a report of two cases and review of the literature. Ther Adv Endocrinol Metab 2017; 8:14-19. [PMID: 28203361 PMCID: PMC5298444 DOI: 10.1177/2042018816678363] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Iron-induced hypophosphataemic osteomalacia remains under-recognized as a potential complication of parenteral iron therapy. We here report two cases of symptomatic hypophosphataemic osteomalacia with multiple insufficiency fractures in the context of chronic gastrointestinal blood loss, necessitating monthly iron polymaltose infusions over prolonged periods of time. Respective blood tests revealed severe hypophosphataemia [0.29 and 0.43; normal range (NR) 0.8-1.5 mmol/l] in the presence of normal serum calcium and 25-hydroxy vitamin D levels. Urinary fractional phosphate excretion was elevated (16% and 24%; NR < 5%) and the tubular maximum phosphate reabsorption was reduced, consistent with renal phosphate wasting. Serum fibroblast growth factor 23 (FGF23) obtained in one patient was significantly elevated at 285 pg/ml (NR < 54 pg/ml). Bone mineral density was significantly reduced and whole-body bone scans revealed metabolic bone disease and multiple insufficiency fractures consistent with osteomalacia. Cessation of iron infusions resulted in clinical and biochemical improvement within 2 months in one patient whereas the second patient required phosphate and calcitriol supplementation to improve symptomatically. Iron-induced hypophosphataemic osteomalacia is thought to be due to reduced degradation of FGF23, resulting in phosphaturia and reduced synthesis of 1,25-dihydroxy vitamin D. Monitoring of patients on long-term parenteral iron is recommended to avoid clinically serious adverse effects.
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Affiliation(s)
| | - Kirtan Ganda
- Department of Endocrinology and Metabolism, Concord Repatriation General Hospital, Concord, NSW, Australia
- Concord Clinical School, Sydney Medical School, University of Sydney, NSW, Australia
| | - Markus J. Seibel
- Department of Endocrinology and Metabolism, Concord Repatriation General Hospital, Concord, NSW, Australia
- Concord Clinical School, Sydney Medical School, University of Sydney, NSW, Australia
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55
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Li X, Zhang D, Bryden WL. Calcium and phosphorus metabolism and nutrition of poultry: are current diets formulated in excess? ANIMAL PRODUCTION SCIENCE 2017. [DOI: 10.1071/an17389] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Calcium (Ca) and phosphorus (P) are important nutrients in poultry diet formulations. In the present review, we discuss recent advances in our understanding of the metabolism of Ca and P in poultry. Recent data are provided in support of the proposition that current poultry diets are formulated in excess for Ca and P. The quantities of Ca and P available for metabolism reflect rates of intestinal absorption, bone accretion and resorption, glomerular filtration, renal tubular reabsorption, and intestinal endogenous losses. Ca and P homeostasis is largely under endocrine control. Parathyroid hormone and the hormonal form of vitamin D3 are the two hormones credited with this role. However, a novel hormonal axis involving Fibroblast Growth Factor 23 and Klotho has been recently delineated, which, in conjunction with parathyroid hormone and vitamin D3, tightly regulates Ca and P homeostasis. Recent studies have suggested that current commercial diets for both broilers and layers contain excess Ca and P, the content of which could be reduced without affecting production or bird welfare. The challenge in reducing Ca and P concentrations in poultry diets is the uncertainty about what concentrations of Ca and P can be fed without compromising bird welfare. This is because there are limited data on the available P and Ca concentrations in poultry feedstuffs determined biologically. This is further complicated by the need for agreement on evaluation systems for evaluation of Ca and P bioavailability. We conclude that direct ileal or pre-caecal digestible Ca and P values are preferred.
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Talaat IM, Nasr A, Alsulaimani AA, Alghamdi H, Alswat KA, Almalki DM, Abushouk A, Saleh AM, Allam G. Association between type 1, type 2 cytokines, diabetic autoantibodies and 25-hydroxyvitamin D in children with type 1 diabetes. J Endocrinol Invest 2016; 39:1425-1434. [PMID: 27541155 DOI: 10.1007/s40618-016-0514-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2016] [Accepted: 07/11/2016] [Indexed: 01/04/2023]
Abstract
PURPOSE Vitamin D may play a role in the pathogenesis of type 1 diabetes (T1D). The aim of the current study was to determine the possible association between 25-hydroxyvitamin D [25(OH)D] levels and circulating levels of type 1 and type 2 cytokines, as well as the pathophysiology of T1D in children. METHODS A total of 250 T1D patients and 250 sex- and age-matched T1D-free controls were screened for 25(OH)D, hemoglobin A1c (HbA1c), type 1 and type 2 cytokines, C-reactive protein (CRP) and bone mineral metabolism, as well as antibodies against insulin, glutamic acid decarboxylase (anti-GAD 65) and islet cells. RESULTS Our data showed that the plasma level of 25(OH)D was significantly lower in T1D patients and that there was a significant negative correlation between 25(OH)D levels and HbA1c values. There was a significant association between deficient levels of 25(OH)D and higher levels of cytokines (IFN-γ, TNF-α, IL-6, IL-1β, IL-4 and IL-10) and CRP. Total blood hemoglobin, the hematocrit percentage, body mass index SDS values, phosphate and magnesium levels were significantly lower in T1D patients than in T1D-free subjects. The levels of parathyroid hormone and alkaline phosphatase were significantly higher in T1D patients. Higher levels of cytokines were significantly associated with deficient levels of 25(OH)D. Moreover, in T1D patients, higher levels of islet antibodies, anti-GAD antibodies and anti-insulin antibodies were significantly associated with deficient levels of 25(OH)D. CONCLUSIONS In type 1 diabetic children, deficient levels of 25(OH)D are associated with high levels of HbA1c, circulatory cytokines and antibody markers.
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Affiliation(s)
- I M Talaat
- Department of Pediatrics, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - A Nasr
- Department of Basic Medical Sciences, College of Medicine, KSAU-HS-Riyadh, Riyadh, Saudi Arabia
- Department of Microbiology, Faculty of Science and Technology, Al-Neelain University, Khartoum, Sudan
| | - A A Alsulaimani
- Department of Pediatrics, College of Medicine, Taif University, Taif, Saudi Arabia
| | - H Alghamdi
- Diabetic Center, Prince Mansour Military Community Hospital, Taif, Saudi Arabia
| | - K A Alswat
- Department of Internal Medicine, College of Medicine, Taif University, Taif, Saudi Arabia
| | - D M Almalki
- Diabetic Center, Prince Mansour Military Community Hospital, Taif, Saudi Arabia
| | - A Abushouk
- Department of Basic Medical Sciences, College of Medicine, KSAU-HS-Riyadh, Riyadh, Saudi Arabia
| | - A M Saleh
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, KSAU-HS-Jeddah, Jeddah, Saudi Arabia
| | - G Allam
- Department of Microbiology and Immunology, College of Medicine, Taif University, P.O. Box: 888, Taif, Saudi Arabia.
- Immunology Section, Department of Zoology, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.
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Effect of phosphate additives on the microstructure, bioactivity, and degradability of microarc oxidation coatings on Mg-Zn-Ca-Mn alloy. Biointerphases 2016; 11:031006. [PMID: 27440396 DOI: 10.1116/1.4959127] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Calcium phosphate coatings were prepared on the surface of self-designed Mg-Zn-Ca-Mn alloy using microarc oxidization technology. To characterize the microstructures, cross-section morphologies, and compositions of the coatings, the authors used scanning electron microscopy equipped with an energy-disperse spectrometer, x-ray diffraction, and Fourier transform infrared spectroscopy. Potentiodynamic polarization in the simulated body fluid (SBF) was used to evaluate the corrosion behaviors of the samples. An SBF immersion test was used to evaluate the coating bioactivity and degradability. After the immersion tests, some bonelike apatite formed on the coating surfaces indicate that bioactivity of the coatings is excellent. The coating prepared in electrolyte containing (NaPO3)6 had slower degradation rate after immersion test for 21 days.
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Reilly BD, Franklin CE. Prevention of muscle wasting and osteoporosis: the value of examining novel animal models. J Exp Biol 2016; 219:2582-95. [DOI: 10.1242/jeb.128348] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
ABSTRACT
Bone mass and skeletal muscle mass are controlled by factors such as genetics, diet and nutrition, growth factors and mechanical stimuli. Whereas increased mechanical loading of the musculoskeletal system stimulates an increase in the mass and strength of skeletal muscle and bone, reduced mechanical loading and disuse rapidly promote a decrease in musculoskeletal mass, strength and ultimately performance (i.e. muscle atrophy and osteoporosis). In stark contrast to artificially immobilised laboratory mammals, animals that experience natural, prolonged bouts of disuse and reduced mechanical loading, such as hibernating mammals and aestivating frogs, consistently exhibit limited or no change in musculoskeletal performance. What factors modulate skeletal muscle and bone mass, and what physiological and molecular mechanisms protect against losses of muscle and bone during dormancy and following arousal? Understanding the events that occur in different organisms that undergo natural periods of prolonged disuse and suffer negligible musculoskeletal deterioration could not only reveal novel regulatory factors but also might lead to new therapeutic options. Here, we review recent work from a diverse array of species that has revealed novel information regarding physiological and molecular mechanisms that dormant animals may use to conserve musculoskeletal mass despite prolonged inactivity. By highlighting some of the differences and similarities in musculoskeletal biology between vertebrates that experience disparate modes of dormancy, it is hoped that this Review will stimulate new insights and ideas for future studies regarding the regulation of atrophy and osteoporosis in both natural and clinical models of muscle and bone disuse.
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Affiliation(s)
- Beau D. Reilly
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Craig E. Franklin
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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van Loon EPM, Little R, Prehar S, Bindels RJM, Cartwright EJ, Hoenderop JGJ. Calcium Extrusion Pump PMCA4: A New Player in Renal Calcium Handling? PLoS One 2016; 11:e0153483. [PMID: 27101128 PMCID: PMC4839660 DOI: 10.1371/journal.pone.0153483] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/17/2016] [Indexed: 11/19/2022] Open
Abstract
Calcium (Ca2+) is vital for multiple processes in the body, and maintenance of the electrolyte concentration is required for everyday physiological function. In the kidney, and more specifically, in the late distal convoluted tubule and connecting tubule, the fine-tuning of Ca2+ reabsorption from the pro-urine takes place. Here, Ca2+ enters the epithelial cell via the transient receptor potential vanilloid receptor type 5 (TRPV5) channel, diffuses to the basolateral side bound to calbindin-D28k and is extruded to the blood compartment via the Na+/Ca2+ exchanger 1 (NCX1) and the plasma membrane Ca2+ ATPase (PMCA). Traditionally, PMCA1 was considered to be the primary Ca2+ pump in this process. However, in recent studies TRPV5-expressing tubules were shown to highly express PMCA4. Therefore, PMCA4 may have a predominant role in renal Ca2+ handling. This study aimed to elucidate the role of PMCA4 in Ca2+ homeostasis by characterizing the Ca2+ balance, and renal and duodenal Ca2+-related gene expression in PMCA4 knockout mice. The daily water intake of PMCA4 knockout mice was significantly lower compared to wild type littermates. There was no significant difference in serum Ca2+ level or urinary Ca2+ excretion between groups. In addition, renal and duodenal mRNA expression levels of Ca2+-related genes, including TRPV5, TRPV6, calbindin-D28k, calbindin-D9k, NCX1 and PMCA1 were similar in wild type and knockout mice. Serum FGF23 levels were significantly increased in PMCA4 knockout mice. In conclusion, PMCA4 has no discernible role in normal renal Ca2+ handling as no urinary Ca2+ wasting was observed. Further investigation of the exact role of PMCA4 in the distal convoluted tubule and connecting tubule is required.
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Affiliation(s)
- Ellen P. M. van Loon
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
| | - Robert Little
- Institute of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, United Kingdom
| | - Sukhpal Prehar
- Institute of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, United Kingdom
| | - René J. M. Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
| | - Elizabeth J. Cartwright
- Institute of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, United Kingdom
| | - Joost G. J. Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
- * E-mail:
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Nucleotide Excision Repair and Vitamin D--Relevance for Skin Cancer Therapy. Int J Mol Sci 2016; 17:372. [PMID: 27058533 PMCID: PMC4848881 DOI: 10.3390/ijms17040372] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/02/2016] [Accepted: 03/04/2016] [Indexed: 02/06/2023] Open
Abstract
Ultraviolet (UV) radiation is involved in almost all skin cancer cases, but on the other hand, it stimulates the production of pre-vitamin D3, whose active metabolite, 1,25-dihydroxyvitamin D3 (1,25VD3), plays important physiological functions on binding with its receptor (vitamin D receptor, VDR). UV-induced DNA damages in the form of cyclobutane pyrimidine dimers or (6-4)-pyrimidine-pyrimidone photoproducts are frequently found in skin cancer and its precursors. Therefore, removing these lesions is essential for the prevention of skin cancer. As UV-induced DNA damages are repaired by nucleotide excision repair (NER), the interaction of 1,25VD3 with NER components can be important for skin cancer transformation. Several studies show that 1,25VD3 protects DNA against damage induced by UV, but the exact mechanism of this protection is not completely clear. 1,25VD3 was also shown to affect cell cycle regulation and apoptosis in several signaling pathways, so it can be considered as a potential modulator of the cellular DNA damage response, which is crucial for mutagenesis and cancer transformation. 1,25VD3 was shown to affect DNA repair and potentially NER through decreasing nitrosylation of DNA repair enzymes by NO overproduction by UV, but other mechanisms of the interaction between 1,25VD3 and NER machinery also are suggested. Therefore, the array of NER gene functioning could be analyzed and an appropriate amount of 1.25VD3 could be recommended to decrease UV-induced DNA damage important for skin cancer transformation.
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Haussler MR, Whitfield GK, Haussler CA, Sabir MS, Khan Z, Sandoval R, Jurutka PW. 1,25-Dihydroxyvitamin D and Klotho: A Tale of Two Renal Hormones Coming of Age. VITAMINS AND HORMONES 2016; 100:165-230. [PMID: 26827953 DOI: 10.1016/bs.vh.2015.11.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
1,25-Dihydroxyvitamin D3 (1,25D) is the renal metabolite of vitamin D that signals through binding to the nuclear vitamin D receptor (VDR). The ligand-receptor complex transcriptionally regulates genes encoding factors stimulating calcium and phosphate absorption plus bone remodeling, maintaining a skeleton with reduced risk of age-related osteoporotic fractures. 1,25D/VDR signaling exerts feedback control of Ca/PO4 via regulation of FGF23, klotho, and CYP24A1 to prevent age-related, ectopic calcification, fibrosis, and associated pathologies. Vitamin D also elicits xenobiotic detoxification, oxidative stress reduction, neuroprotective functions, antimicrobial defense, immunoregulation, anti-inflammatory/anticancer actions, and cardiovascular benefits. Many of the healthspan advantages conferred by 1,25D are promulgated by its induction of klotho, a renal hormone that is an anti-aging enzyme/coreceptor that protects against skin atrophy, osteopenia, hyperphosphatemia, endothelial dysfunction, cognitive defects, neurodegenerative disorders, and impaired hearing. In addition to the high-affinity 1,25D hormone, low-affinity nutritional VDR ligands including curcumin, polyunsaturated fatty acids, and anthocyanidins initiate VDR signaling, whereas the longevity principles resveratrol and SIRT1 potentiate VDR signaling. 1,25D exerts actions against neural excitotoxicity and induces serotonin mood elevation to support cognitive function and prosocial behavior. Together, 1,25D and klotho maintain the molecular signaling systems that promote growth (p21), development (Wnt), antioxidation (Nrf2/FOXO), and homeostasis (FGF23) in tissues crucial for normal physiology, while simultaneously guarding against malignancy and degeneration. Therefore, liganded-VDR modulates the expression of a "fountain of youth" array of genes, with the klotho target emerging as a major player in the facilitation of health span by delaying the chronic diseases of aging.
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Affiliation(s)
- Mark R Haussler
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, Arizona, USA.
| | - G Kerr Whitfield
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, Arizona, USA
| | - Carol A Haussler
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, Arizona, USA
| | - Marya S Sabir
- School of Mathematical and Natural Sciences, Arizona State University, Glendale, Arizona, USA
| | - Zainab Khan
- School of Mathematical and Natural Sciences, Arizona State University, Glendale, Arizona, USA
| | - Ruby Sandoval
- School of Mathematical and Natural Sciences, Arizona State University, Glendale, Arizona, USA
| | - Peter W Jurutka
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, Arizona, USA; School of Mathematical and Natural Sciences, Arizona State University, Glendale, Arizona, USA
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Jiang S, Jiang Z, Yang K, Chen F, Zheng C, Wang L. Dietary vitamin D3 requirement of Chinese yellow-feathered broilers. Poult Sci 2015. [DOI: 10.3382/ps/pev163] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Gruson D, Ferracin B, Ahn SA, Zierold C, Blocki F, Hawkins DM, Bonelli F, Rousseau MF. 1,25-Dihydroxyvitamin D to PTH(1-84) Ratios Strongly Predict Cardiovascular Death in Heart Failure. PLoS One 2015; 10:e0135427. [PMID: 26308451 PMCID: PMC4550259 DOI: 10.1371/journal.pone.0135427] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 07/21/2015] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES Vitamin D deficiency and hyperparathyroidism are common in patients with heart failure (HF). There is a growing body of evidence supporting the role of vitamin D and parathyroid hormone (PTH) in cardiac remodeling and worsening of HF. Lack of reliable automated testing of 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active metabolite of vitamin D, has limited its contribution to the prognostic assessment of HF. Here, the association of 1,25(OH)2D and PTH(1-84) levels was evaluated for prediction of cardiovascular death in chronic HF patients. METHODS We conducted a single center prospective cohort including 170 chronic HF patients (females n = 36; males n = 134; NYHA II-IV; mean age: 67 years; etiology: ischemic n = 119, dilated cardiomyopathy n = 51; mean LVEF: 23%). The primary outcome was cardiovascular death. RESULTS Serum levels of 1,25(OH)2D decreased markedly with increased HF severity. Medians were 33.3 pg/mL for NYHA-II patients, 23.4 pg/mL for NYHA-III, and 14.0 pg/mL for NYHA-IV patients (p<0.001). Most patients had levels of 25(OH)D below 30ng/mL, and stratification by NYHA functional class did not show significant differences (p = 0.249). The 1,25(OH)2D to PTH(1-84) ratio and the (1,25(OH)2D)2 to PTH(1-84) ratio were found to be the most significantly related to HF severity. After a median follow-up of 4.1 years, 106 out of 170 patients reached the primary endpoint. Cox proportional hazard modeling revealed 1,25(OH)2D and the 1,25(OH)2D to PTH(1-84) ratios to be strongly predictive of outcomes. CONCLUSIONS 1,25(OH)2D and its ratios to PTH(1-84) strongly and independently predict cardiovascular mortality in chronic HF.
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Affiliation(s)
- Damien Gruson
- Pôle de recherche en Endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Cliniques Universitaires St-Luc and Université Catholique de Louvain, Brussels, Belgium
- Department of Laboratory Medicine, Cliniques Universitaires St-Luc and Université Catholique de Louvain, Brussels, Belgium
| | - Benjamin Ferracin
- Pôle de recherche en Endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Cliniques Universitaires St-Luc and Université Catholique de Louvain, Brussels, Belgium
| | - Sylvie A. Ahn
- Division of Cardiology, Cliniques Universitaires St-Luc and Pôle de recherche cardiovasculaire, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
| | - Claudia Zierold
- DiaSorin Inc, 1951 Northwestern Avenue, Stillwater, Minnesota, 55082, United States of America
| | - Frank Blocki
- DiaSorin Inc, 1951 Northwestern Avenue, Stillwater, Minnesota, 55082, United States of America
| | - Douglas M. Hawkins
- School of Statistics, University of Minnesota, Minneapolis, Minnesota, 55455, United States of America
| | - Fabrizio Bonelli
- DiaSorin Inc, 1951 Northwestern Avenue, Stillwater, Minnesota, 55082, United States of America
| | - Michel F. Rousseau
- Division of Cardiology, Cliniques Universitaires St-Luc and Pôle de recherche cardiovasculaire, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
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Cross-sectional analysis of serum calcium levels for associations with left ventricular hypertrophy in normocalcemia individuals with type 2 diabetes. Cardiovasc Diabetol 2015; 14:43. [PMID: 25924883 PMCID: PMC4422420 DOI: 10.1186/s12933-015-0200-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 03/15/2015] [Indexed: 01/19/2023] Open
Abstract
Background Left ventricular hypertrophy (LVH) is prevalent in patients with type 2 diabetes mellitus (T2DM). Recent studies show that an increase in albumin-adjusted serum calcium level is associated with an elevated risk of T2DM. We speculate that increased serum calcium levels in T2DM patients are related to LVH prevalence. Methods In this echocardiographic study, 833 normocalcemia and normophosphatemia patients with T2DM were enrolled. The associations between serum calcium and metabolic parameters, left ventricular mass index (LVMI), as well as the rate of LVH were examined using bivariate linear correlation, multivariate linear regression and logistic regression, respectively. The predictive performance of serum calcium for LVH was evaluated using the area under the receiver operating characteristic curve (AUC). Results Patients with LVH have significantly higher serum calcium than those without LVH. Serum calcium was positively associated with total cholesterol, triglycerides, low-density lipoprotein cholesterol, serum uric acid, HOMA-IR and fasting plasma glucose. Multivariate linear regression analysis demonstrated that serum calcium was independently associated with LVMI (p < 0.001). In comparison with patients in the lowest serum calcium quartile, the odds ratio (OR) for LVH in patients in the highest quartile was 2.909 (95% CI 1.792-4.720; p < 0.001). When serum calcium was analyzed as a continuous variable, per 1 mg/dl increase, the OR (95% CI) for LVH was [2.400 (1.552-3.713); p < 0.001]. Serum calcium can predict LVH (AUC = 0.617; 95% CI (0.577-0.656); p < 0.001). Conclusions Albumin-adjusted serum calcium is associated with an increased risk of LVH in patients with T2DM.
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de Baaij JHF, Hoenderop JGJ, Bindels RJM. Magnesium in man: implications for health and disease. Physiol Rev 2015; 95:1-46. [PMID: 25540137 DOI: 10.1152/physrev.00012.2014] [Citation(s) in RCA: 880] [Impact Index Per Article: 97.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Magnesium (Mg(2+)) is an essential ion to the human body, playing an instrumental role in supporting and sustaining health and life. As the second most abundant intracellular cation after potassium, it is involved in over 600 enzymatic reactions including energy metabolism and protein synthesis. Although Mg(2+) availability has been proven to be disturbed during several clinical situations, serum Mg(2+) values are not generally determined in patients. This review aims to provide an overview of the function of Mg(2+) in human health and disease. In short, Mg(2+) plays an important physiological role particularly in the brain, heart, and skeletal muscles. Moreover, Mg(2+) supplementation has been shown to be beneficial in treatment of, among others, preeclampsia, migraine, depression, coronary artery disease, and asthma. Over the last decade, several hereditary forms of hypomagnesemia have been deciphered, including mutations in transient receptor potential melastatin type 6 (TRPM6), claudin 16, and cyclin M2 (CNNM2). Recently, mutations in Mg(2+) transporter 1 (MagT1) were linked to T-cell deficiency underlining the important role of Mg(2+) in cell viability. Moreover, hypomagnesemia can be the consequence of the use of certain types of drugs, such as diuretics, epidermal growth factor receptor inhibitors, calcineurin inhibitors, and proton pump inhibitors. This review provides an extensive and comprehensive overview of Mg(2+) research over the last few decades, focusing on the regulation of Mg(2+) homeostasis in the intestine, kidney, and bone and disturbances which may result in hypomagnesemia.
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Affiliation(s)
- Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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Lameris AL, Nevalainen PI, Reijnen D, Simons E, Eygensteyn J, Monnens L, Bindels RJM, Hoenderop JGJ. Segmental transport of Ca²⁺ and Mg²⁺ along the gastrointestinal tract. Am J Physiol Gastrointest Liver Physiol 2015; 308:G206-16. [PMID: 25477372 DOI: 10.1152/ajpgi.00093.2014] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Calcium (Ca(2+)) and magnesium (Mg(2+)) ions are involved in many vital physiological functions. Since dietary intake is the only source of minerals for the body, intestinal absorption is essential for normal homeostatic levels. The aim of this study was to characterize the absorption of Ca(2+) as well as Mg(2+) along the gastrointestinal tract at a molecular and functional level. In both humans and mice the Ca(2+) channel transient receptor potential vanilloid subtype 6 (TRPV6) is expressed in the proximal intestinal segments, whereas Mg(2+) channel transient receptor potential melastatin subtype 6 (TRPM6) is expressed in the distal parts of the intestine. A method was established to measure the rate of Mg(2+) absorption from the intestine in a time-dependent manner by use of (25)Mg(2+). In addition, local absorption of Ca(2+) and Mg(2+) in different segments of the intestine of mice was determined by using surgically implanted intestinal cannulas. By these methods, it was demonstrated that intestinal absorption of Mg(2+) is regulated by dietary needs in a vitamin D-independent manner. Also, it was shown that at low luminal concentrations, favoring transcellular absorption, Ca(2+) transport mainly takes place in the proximal segments of the intestine, whereas Mg(2+) absorption predominantly occurs in the distal part of the gastrointestinal tract. Vitamin D treatment of mice increased serum Mg(2+) levels and 24-h urinary Mg(2+) excretion, but not intestinal absorption of (25)Mg(2+). Segmental cannulation of the intestine and time-dependent absorption studies using (25)Mg(2+) provide new ways to study intestinal Mg(2+) absorption.
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Affiliation(s)
- Anke L Lameris
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Pasi I Nevalainen
- School of Medicine, University of Tampere, Tampere, Finland; Department of Internal Medicine, Tampere University Hospital, Tampere, Finland
| | - Daphne Reijnen
- Central Animal Facility, Radboud University, Nijmegen, The Netherlands; and
| | - Ellen Simons
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jelle Eygensteyn
- Department of General Instrumentation, Faculty of Sciences, Radboud University, Nijmegen, The Netherlands
| | - Leo Monnens
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - René J M Bindels
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
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Luo X, Barbieri D, Zhang Y, Yan Y, Bruijn JD, Yuan H. Strontium-Containing Apatite/Poly Lactide Composites Favoring Osteogenic Differentiation and in Vivo Bone Formation. ACS Biomater Sci Eng 2015. [DOI: 10.1021/ab500005e] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Xiaoman Luo
- Xpand Biotechnology BV, Professor
Bronkhorstlaan 10, Bld 48, 3723MB Bilthoven, The Netherlands
- MIRA
Institute, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
| | - Davide Barbieri
- Xpand Biotechnology BV, Professor
Bronkhorstlaan 10, Bld 48, 3723MB Bilthoven, The Netherlands
| | - Yunfei Zhang
- Chongqing Academy of Metrology and Quality Inspection, Yangliu North Road No. 1, Yubei
District, 401123 Chongqing, China
| | - Yonggang Yan
- College
of Physical Science and Technology, Sichuan University, Wangjiang
Road 29, 610064 Chengdu, China
| | - Joost D. Bruijn
- Xpand Biotechnology BV, Professor
Bronkhorstlaan 10, Bld 48, 3723MB Bilthoven, The Netherlands
- MIRA
Institute, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
- School
of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Huipin Yuan
- Xpand Biotechnology BV, Professor
Bronkhorstlaan 10, Bld 48, 3723MB Bilthoven, The Netherlands
- MIRA
Institute, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
- College
of Physical Science and Technology, Sichuan University, Wangjiang
Road 29, 610064 Chengdu, China
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Nagai N, Ogata F, Kawasaki N, Ito Y, Funakami Y, Okamoto N, Shimomura Y. Hypercalcemia Leads to Delayed Corneal Wound Healing in Ovariectomized Rats. Biol Pharm Bull 2015; 38:1063-9. [DOI: 10.1248/bpb.b15-00227] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
| | | | | | | | | | - Norio Okamoto
- Department of Ophthalmology, Faculty of Medicine, Kinki University
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D. Murray R, D. Lederer E, J. Khundmiri S. Role of PTH in the Renal Handling of Phosphate. AIMS MEDICAL SCIENCE 2015. [DOI: 10.3934/medsci.2015.3.162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Wulaningsih W, Van Hemelrijck M, Michaelsson K, Kanarek N, Nelson WG, Ix JH, Platz EA, Rohrmann S. Association of serum inorganic phosphate with sex steroid hormones and vitamin D in a nationally representative sample of men. Andrology 2014; 2:967-76. [PMID: 25270590 PMCID: PMC4324600 DOI: 10.1111/andr.285] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 08/31/2014] [Accepted: 09/01/2014] [Indexed: 12/14/2022]
Abstract
Defects in bone regulatory pathways have been linked to chronic diseases including cardiovascular disease and cancer. In men, a link between bone metabolism and gonadal hormones has been suggested. However, to date, there is lack of evidence on the association between serum inorganic phosphate (Pi) and sex steroid hormones. The objective of this study was to investigate the association between Pi, sex steroid hormones and a known Pi metabolic regulator, vitamin D, in men in the National Health and Nutrition Examination Survey III (NHANES III). From NHANES III, we selected 1412 men aged 20+ who participated in the morning session of Phase I (1988-1991) with serum measurements of Pi, sex hormones, and vitamin D. Multivariable linear regression was used to calculate crude and geometric mean Pi by total and estimated free testosterone and estradiol, sex hormone-binding globulin, androstanediol glucuronide (AAG), and vitamin D. Similar analyses were performed while stratifying by race/ethnicity and vitamin D levels. We found a lack of statistically significant difference in geometric means of Pi across quintiles of concentrations of sex hormones, indicating a tight regulation of Pi. However, Pi levels were inversely associated with calculated free testosterone in non-Hispanic black men, with geometric mean levels of Pi of 1.16 and 1.02 ng/mL for those in the lowest and highest quintiles of free testosterone, respectively (p-trend < 0.05). A similar but weaker pattern was seen between total testosterone and Pi. An inverse association was also seen between AAG and Pi in men with vitamin D concentration below the median (<24.2 ng/mL). No associations were observed among men with vitamin D levels at or above the median. Our findings suggest a weak link among sex hormones, vitamin D, and Pi in men. The observed effects of race/ethnicity and vitamin D indicate a complex association involving various regulators of Pi homeostasis.
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Affiliation(s)
- W Wulaningsih
- Cancer Epidemiology Unit, Division of Cancer Studies, King's College London, School of Medicine, London, UK
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Abstract
Technological advances in the large scale analysis of human genetics have generated profound insights into possible genetic contributions to chronic diseases including the inflammatory bowel diseases (IBDs), Crohn's disease and ulcerative colitis. To date, 163 distinct genetic risk loci have been associated with either Crohn's disease or ulcerative colitis, with a substantial degree of genetic overlap between these 2 conditions. Although many risk variants show a reproducible correlation with disease, individual gene associations only affect a subset of patients, and the functional contribution(s) of these risk variants to the onset of IBD is largely undetermined. Although studies in twins have demonstrated that the development of IBD is not mediated solely by genetic risk, it is nevertheless important to elucidate the functional consequences of risk variants for gene function in relevant cell types known to regulate key physiological processes that are compromised in IBD. This article will discuss IBD candidate genes that are known to be, or are suspected of being, involved in regulating the intestinal epithelial barrier and several of the physiological processes presided over by this dynamic and versatile layer of cells. This will include assembly and regulation of tight junctions, cell adhesion and polarity, mucus and glycoprotein regulation, bacterial sensing, membrane transport, epithelial differentiation, and restitution.
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Stoerger C, Flockerzi V. The transient receptor potential cation channel subfamily V member 6 (TRPV6): genetics, biochemical properties, and functions of exceptional calcium channel proteins. Biochem Cell Biol 2014; 92:441-8. [PMID: 25372600 DOI: 10.1139/bcb-2014-0063] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The transient receptor potential cation channel subfamily V member 6 (TRPV6) gene and cDNA were identified 15 years ago and exceptional observations on TrpV6 proteins and their function as a Ca(2+)-selective cation channel have been made since then. In this review we will summarize recent studies regarding the genetics, biochemical properties, and physiological functions of murine and human TrpV6 channel proteins. We will focus on TRPV6 gene polymorphisms, the start of TRPV6 translation at a non-AUG codon and the functions of TRPV6 in intestinal Ca(2+) uptake, sperm maturation, and male fertility.
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Affiliation(s)
- Christof Stoerger
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany
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Inhibition of vascular calcification by block of intermediate conductance calcium-activated potassium channels with TRAM-34. Pharmacol Res 2014; 85:6-14. [DOI: 10.1016/j.phrs.2014.04.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Revised: 04/25/2014] [Accepted: 04/27/2014] [Indexed: 01/08/2023]
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74
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Mutations in the vitamin D receptor and hereditary vitamin D-resistant rickets. BONEKEY REPORTS 2014; 3:510. [PMID: 24818002 DOI: 10.1038/bonekey.2014.5] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 09/27/2013] [Indexed: 12/24/2022]
Abstract
Heterogeneous loss of function mutations in the vitamin D receptor (VDR) interfere with vitamin D signaling and cause hereditary vitamin D-resistant rickets (HVDRR). HVDRR is characterized by hypocalcemia, secondary hyperparathyroidism and severe early-onset rickets in infancy and is often associated with consanguinity. Affected children may also exhibit alopecia of the scalp and total body. The children usually fail to respond to treatment with calcitriol; in fact, their endogenous levels are often very elevated. Successful treatment requires reversal of hypocalcemia and secondary hyperparathyroidism and is usually accomplished by administration of high doses of calcium given either intravenously or sometimes orally to bypass the intestinal defect in VDR signaling.
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Abstract
Chronic kidney disease-mineral and bone disorder (CKD-MBD) is characterized by bone abnormalities, vascular calcification, and an array of laboratory abnormalities. The latter classically include disturbances in the parathyroid hormone/vitamin D axis. More recently, fibroblast growth factor 23 (FGF23) and klotho also have been identified as important regulators of mineral metabolism. Klotho deficiency and high circulating FGF23 levels precede secondary hyperparathyroidism in CKD patients. Levels of FGF23 and parathyroid hormone increase along the progression of CKD to maintain mineral homeostasis and to overcome end-organ resistance. It is hard to define when the increase of both hormones becomes maladaptive. CKD-MBD is associated with adverse outcomes including cardiovascular disease and mortality. This review summarizes the complex pathophysiology of CKD-MBD and outlines which laboratory abnormalities represent biomarkers of disease severity, which laboratory abnormalities are predictors of cardiovascular disease, and which laboratory abnormalities should be considered (direct) uremic toxins exerting organ damage. This information may help to streamline current and future therapeutic efforts.
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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.
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Affiliation(s)
- Brian L Foster
- National Institute for Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892
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Ding Y, Wen C, Hodgson P, Li Y. Effects of alloying elements on the corrosion behavior and biocompatibility of biodegradable magnesium alloys: a review. J Mater Chem B 2014; 2:1912-1933. [DOI: 10.1039/c3tb21746a] [Citation(s) in RCA: 297] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review elaborates the effects of alloying elements on the microstructure, mechanical properties, corrosion and biocompatibility of biodegradable magnesium alloys.
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Affiliation(s)
- Yunfei Ding
- Institute for Frontier Materials
- Deakin University
- Geelong, Australia
| | - Cuie Wen
- Faculty of Science
- Engineering and Technology
- Swinburne University of Technology
- Hawthorn, Australia
| | - Peter Hodgson
- Institute for Frontier Materials
- Deakin University
- Geelong, Australia
| | - Yuncang Li
- Institute for Frontier Materials
- Deakin University
- Geelong, Australia
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In vitro and in vivo degradation evaluation of novel iron-bioceramic composites for bone implant applications. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2013; 36:336-44. [PMID: 24433920 DOI: 10.1016/j.msec.2013.12.022] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 11/06/2013] [Accepted: 12/17/2013] [Indexed: 11/20/2022]
Abstract
Biodegradable metals such as magnesium, iron and their alloys have been known as potential materials for temporary medical implants. However, most of the studies on biodegradable metals have been focusing on optimizing their mechanical properties and degradation behavior with no emphasis on improving their bioactivity behavior. We therefore investigated the possibility of improving iron biodegradation rate and bioactivity by incorporating various bioactive bioceramics. The iron-based bioceramic (hydroxyapatite, tricalcium phosphate and biphasic calcium phosphate) composites were prepared by mechanical mixing and sintering process. Degradation studies indicated that the addition of bioceramics lowered the corrosion potential of the composites and slightly increased their corrosion rate compared to that of pure iron. In vitro cytotoxicity results showed an increase of cellular activity when rat smooth muscle cells interacted with the degrading composites compared to pure iron. X-ray radiogram analysis showed a consistent degradation progress with that found in vivo and positive tissue response up to 70 days implantation in sheep animal model. Therefore, the iron-based bioceramic composites have the potential to be used for biodegradable bone implant applications.
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Montalcini T, Terracciano R, Romeo S, Foti D, Gulletta E, Costanzo FS, Pujia A. Postmenopausal women with carotid atherosclerosis: potential role of the serum calcium levels. Nutr Metab Cardiovasc Dis 2013; 23:1141-1146. [PMID: 23466180 DOI: 10.1016/j.numecd.2012.12.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 11/08/2012] [Accepted: 12/14/2012] [Indexed: 10/27/2022]
Abstract
BACKGROUND AND AIM Studies on the association between serum calcium levels and cardiovascular diseases suggested a causative role for hypercalcemia but other studies showed that even serum calcium levels within normal range could be involved in atherosclerosis. However, while dietary calcium intake does not seem to be related to adverse cardiovascular effects, the association between calcium supplementation and the cardiovascular events has not been fully proven. Our aim was to determine the relation between serum calcium levels, within normal range, and the presence of carotid atherosclerosis in a population in whom investigations on this topic are lacking, the postmenopausal women. METHODS AND RESULTS In this retrospective study, participants were recruited from women aged 49-65 years who underwent an ultrasonography evaluation of the carotid arteries between years 2008-2012. The study included 413 subjects with serum calcium level available, without symptomatic cardiovascular disease. A physical examination, including the evaluation of body mass index, waist and hip circumferences and the blood pressure, as well as, a collection of a venous blood sample was performed. The mean age was 56 ± 7 years. The prevalence of the carotid atherosclerosis was 50.8%. The comparison between women with and without carotid atherosclerosis showed differences for the classical risk factors and for serum calcium levels (p = 0.001). The logistic regression analysis, adjusting for these risk factors, confirmed the association between serum calcium levels and carotid atherosclerosis (p = 0.011). Furthermore, we showed an increasing prevalence of carotid atherosclerosis from lower to higher calcium quartiles (p = 0.016). CONCLUSION We found a positive relation between serum calcium levels and the carotid atherosclerosis in postmenopausal women. This study may suggest a redetermination of the reference range of calcemia, at least in menopause.
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Affiliation(s)
- T Montalcini
- Clinical Nutrition Unit, Department of Medical and Surgical Science, University Magna Grecia, Catanzaro, Viale S. Venuta, 88100 Catanzaro, Italy.
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van Angelen AA, San-Cristobal P, Pulskens WP, Hoenderop JG, Bindels RJ. The impact of dietary magnesium restriction on magnesiotropic and calciotropic genes. Nephrol Dial Transplant 2013; 28:2983-93. [DOI: 10.1093/ndt/gft358] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Ye Z, Palazzo JP, Lin L, Lai Y, Guiles F, Myers RE, Han J, Xing J, Yang H. Postoperative hyperphosphatemia significantly associates with adverse survival in colorectal cancer patients. J Gastroenterol Hepatol 2013; 28:1469-75. [PMID: 23611210 PMCID: PMC3775915 DOI: 10.1111/jgh.12237] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/11/2013] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIM Hyperphosphatemia has been implicated in the development and treatment of various cancers. However, whether it can be used as a direct prognostic marker of colorectal cancer (CRC) has remained unexplored. Given new insights into the importance of hyperphosphatemia in CRC, we sought to evaluate the association of hyperphosphatemia with the clinical outcomes of this disease. METHODS In a retrospective analysis of a well-characterized clinic-based cohort with 1241 CRC patients, we assessed the association of postoperative hyperphosphatemia with patient overall survival. RESULTS Postoperative hyperphosphatemia measured within the first month after surgery was significantly associated with CRC survival. Compared to patients with a normal phosphate level, those with hyperphosphatemia exhibited a significant unfavorable overall survival with a hazard ratio (HR) of 1.84 (95% confidence interval [CI] 1.49-2.29, P = 2.6 × 10(-8) (log-rank P = 1.2 × 10(-7) ). Stratified analyses indicated the association was more pronounced in patients with colon (HR = 2.00, 95% CI 1.57-2.56, P = 3.17 × 10(-8) ) but not rectal cancer (HR = 0.96, 95% CI 0.58-1.59, P = 0.889) (P interaction = 0.023), as well as in those not receiving chemotherapy (HR = 2.15, 95% CI 1.59-2.90, P = 6.2 × 10(-7) ) but not in those receiving chemotherapy (HR = 1.30, 95% CI 0.92-1.82, P = 0.136) (P interaction = 0.012). Flexible parametric survival model demonstrated that the increased risk for death conferred by postoperative hyperphosphatemia persisted over 150 months after surgery. CONCLUSION Our data indicated that postoperative hyperphosphatemia might be used as a prognostic marker of CRC patients after surgery. Since phosphate level is routinely tested in clinics, it may be incorporated into clinical models to predict CRC survival.
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Affiliation(s)
- Zhong Ye
- Division of Population Science, Department of Medical Oncology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Juan P. Palazzo
- Department of Pathology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Liz Lin
- Division of Population Science, Department of Medical Oncology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Yinzhi Lai
- Division of Population Science, Department of Medical Oncology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Fran Guiles
- Oncology Data Service, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Ronald E. Myers
- Division of Population Science, Department of Medical Oncology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Jin Han
- Department of Pharmacy, Rush University Medical Center, Chicago, IL 60612
| | - Jinliang Xing
- Experimental Teaching Center, Fourth Military Medical University, Xi’an, 710032, China
| | - Hushan Yang
- Division of Population Science, Department of Medical Oncology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA,Correspondence to: Hushan Yang, PhD, Division of Population Science, Department of Medical Oncology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA. Tel: 215-503-6521; Fax: 267-336-0247;
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Wu-Wong JR, Nakane M, Chen YW, Mizobuchi M. Mechanistic analysis for time-dependent effects of cinacalcet on serum calcium, phosphorus, and parathyroid hormone levels in 5/6 nephrectomized rats. Physiol Rep 2013; 1:e00046. [PMID: 24303131 PMCID: PMC3835002 DOI: 10.1002/phy2.46] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 07/05/2013] [Accepted: 07/08/2013] [Indexed: 12/21/2022] Open
Abstract
This study investigates the time-dependent effects of cinacalcet on serum calcium, phosphorus, and parathyroid hormone (PTH) levels in 5/6 nephrectomized (NX) rats with experimental chronic renal insufficiency. In this study, 5/6 NX male, Sprague-Dawley rats were treated with vehicle or cinacalcet (10 mg/kg, oral, 1× daily). On Day 0 (before treatment), Day 12 and 13 after treatment (to approximate the clinical practice), and also at 0, 1, 4, 8, 16, and 24 hours after the last dosing, blood was collected for analysis. After 12 or 13 days of cinacalcet treatment, modest changes were observed in serum Ca and phosphorus (Pi), while PTH decreased by >45% to Sham levels (152 ± 15 pg/mL). Detailed mapping found that cinacalcet caused a significant time-dependent decrease in serum Ca following dosing, reaching a lowest point at 8 hours (decrease by 20% to 8.43 ± 0.37 mg/dL), and then returning to normal at 24 hours. Cinacalcet also caused a significant increase in serum Pi levels (by 18%). To investigate the potential mechanism of action, a broad approach was taken by testing cinacalcet in a panel of 77 protein-binding assays. Cinacalcet interacted with several channels, transporters, and neurotransmitter receptors, some of which are involved in brain and heart, and may impact Ca homeostasis. Cinacalcet dose-dependently increased brain natriuretic peptide (BNP) mRNA expression by 48% in cardiomyocytes, but had no significant effects on left ventricular hypertrophy and cardiac function. The results suggest that cinacalcet's hypocalcemic effect may be due to its nonspecific interaction with other receptors in brain and heart.
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Affiliation(s)
- J Ruth Wu-Wong
- Department of Pharmacy Practice, University of Illinois at Chicago Chicago, Illinois
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83
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Rievaj J, Pan W, Cordat E, Alexander RT. The Na⁺/H⁺ exchanger isoform 3 is required for active paracellular and transcellular Ca²⁺ transport across murine cecum. Am J Physiol Gastrointest Liver Physiol 2013; 305:G303-13. [PMID: 23764894 PMCID: PMC4959879 DOI: 10.1152/ajpgi.00490.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intestinal calcium (Ca²⁺) absorption occurs via paracellular and transcellular pathways. Although the transcellular route has been extensively studied, mechanisms mediating paracellular absorption are largely unexplored. Unlike passive diffusion, secondarily active paracellular Ca²⁺ uptake occurs against an electrochemical gradient with water flux providing the driving force. Water movement is dictated by concentration differences that are largely determined by Na⁺ fluxes. Consequently, we hypothesized that Na⁺ absorption mediates Ca²⁺ flux. NHE3 is central to intestinal Na⁺ absorption. NHE3 knockout mice (NHE3-/-) display impaired intestinal Na⁺, water, and Ca²⁺ absorption. However, the mechanism mediating this latter abnormality is not clear. To investigate this, we used Ussing chambers to measure net Ca²⁺ absorption across different segments of wild-type mouse intestine. The cecum was the only segment with net Ca²⁺ absorption. Quantitative RT-PCR measurements revealed cecal expression of all genes implicated in intestinal Ca²⁺ absorption, including NHE3. We therefore employed this segment for further studies. Inhibition of NHE3 with 100 μM 5-(N-ethyl-N-isopropyl) amiloride decreased luminal-to-serosal and increased serosal-to-luminal Ca²⁺ flux. NHE3-/- mice had a >60% decrease in luminal-to-serosal Ca²⁺ flux. Ussing chambers experiments under altered voltage clamps (-25, 0, +25 mV) showed decreased transcellular and secondarily active paracellular Ca²⁺ absorption in NHE3-/- mice relative to wild-type animals. Consistent with this, cecal Trpv6 expression was diminished in NHE3-/- mice. Together these results implicate NHE3 in intestinal Ca(2+) absorption and support the theory that this is, at least partially, due to the role of NHE3 in Na⁺ and water absorption.
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Affiliation(s)
- Juraj Rievaj
- Dept. of Pediatrics, 4-585 Edmonton Clinic Health Academy, 11405 87th Ave., Univ. of Alberta, Edmonton, Alberta, T6G 2R7, Canada.
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84
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Imai Y, Youn MY, Inoue K, Takada I, Kouzmenko A, Kato S. Nuclear receptors in bone physiology and diseases. Physiol Rev 2013; 93:481-523. [PMID: 23589826 PMCID: PMC3768103 DOI: 10.1152/physrev.00008.2012] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
During the last decade, our view on the skeleton as a mere solid physical support structure has been transformed, as bone emerged as a dynamic, constantly remodeling tissue with systemic regulatory functions including those of an endocrine organ. Reflecting this remarkable functional complexity, distinct classes of humoral and intracellular regulatory factors have been shown to control vital processes in the bone. Among these regulators, nuclear receptors (NRs) play fundamental roles in bone development, growth, and maintenance. NRs are DNA-binding transcription factors that act as intracellular transducers of the respective ligand signaling pathways through modulation of expression of specific sets of cognate target genes. Aberrant NR signaling caused by receptor or ligand deficiency may profoundly affect bone health and compromise skeletal functions. Ligand dependency of NR action underlies a major strategy of therapeutic intervention to correct aberrant NR signaling, and significant efforts have been made to design novel synthetic NR ligands with enhanced beneficial properties and reduced potential negative side effects. As an example, estrogen deficiency causes bone loss and leads to development of osteoporosis, the most prevalent skeletal disorder in postmenopausal women. Since administration of natural estrogens for the treatment of osteoporosis often associates with undesirable side effects, several synthetic estrogen receptor ligands have been developed with higher therapeutic efficacy and specificity. This review presents current progress in our understanding of the roles of various nuclear receptor-mediated signaling pathways in bone physiology and disease, and in development of advanced NR ligands for treatment of common skeletal disorders.
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Affiliation(s)
- Yuuki Imai
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan.
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85
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Abstract
The main physiological actions of the biologically most active metabolite of vitamin D, 1α,25-dihydroxyvitamin D(3) (1α,25(OH)(2)D(3)), are calcium and phosphorus uptake and transport and thereby controlling bone formation. Other emergent areas of 1α,25(OH)(2)D(3) action are in the control of immune functions, cellular growth and differentiation. All genomic actions of 1α,25(OH)(2)D(3) are mediated by the transcription factor vitamin D receptor (VDR) that has been the subject of intense study since the 1980's. Thus, vitamin D signaling primarily implies the molecular actions of the VDR. In this review, we present different perspectives on the VDR that incorporate its role as transcription factor and member of the nuclear receptor superfamily, its dynamic changes in genome-wide locations and DNA binding modes, its interaction with chromatin components and its primary protein-coding and non-protein coding target genes and finally how these aspects are united in regulatory networks. By comparing the actions of the VDR, a relatively well-understood and characterized protein, with those of other transcription factors, we aim to build a realistic positioning of vitamin D signaling in the context of other intracellular signaling systems.
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Affiliation(s)
- Carsten Carlberg
- School of Medicine, Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
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86
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Wolber FM, Beck KL, Conlon CA, Kruger MC. Kiwifruit and Mineral Nutrition. NUTRITIONAL BENEFITS OF KIWIFRUIT 2013; 68:233-56. [DOI: 10.1016/b978-0-12-394294-4.00013-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Wu-Wong JR, Nakane M, Chen YW. Mapping the time-dependent effects of paricalcitol on serum calcium, phosphorus and parathyroid hormone levels in 5/6 nephrectomized uremic rats. Life Sci 2012; 92:161-6. [PMID: 23261531 DOI: 10.1016/j.lfs.2012.11.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 10/24/2012] [Accepted: 11/20/2012] [Indexed: 01/20/2023]
Abstract
AIMS To investigate whether the frequency of monitoring paricalcitol's impact on serum calcium (Ca), phosphorus and PTH in current clinical practice is sufficient by mapping the time-dependent effects of paricalcitol on these parameters. MAIN METHODS The 5/6 nephrectomized (NX) male, Sprague-Dawley rats with established uremia were treated with vehicle or paricalcitol (0.16 μg/kg, i.p., 3×/week). On Day 0 (before treatment), Days 12 and 13 after treatment, and also at 0, 1, 4, 8, 16, 24 h after the last dosing, blood and small intestine samples were collected. KEY FINDINGS Serum creatinine and blood urea nitrogen levels were significantly elevated in 5/6 NX rats. Significant increases were observed in serum Ca while PTH decreased by >90% when the parameters were determined at 12 or 13 days after paricalcitol dosing. Paricalcitol caused a step-wise increase in serum Ca levels at 1-24 h following dosing, reduced serum PTH levels with PTH values ranging from 1.06±0.06 to 26.7±25.7 pg/ml (vs. 152±15 pg/ml in Sham rats), but did not affect serum phosphorus in a time-dependent manner. Consistent with the serum Ca data, paricalcitol significantly induced the intestinal expression of Calb3 and TRPV6, genes involved in intestinal Ca transport, and also significantly induced the intestinal calcium absorption. SIGNIFICANCE Our results suggest that the frequency of monitoring paricalcitol's effect on serum Ca, phosphorus and PTH in current clinical practice seems adequate. Additional clinical trials may be needed to resolve the inconsistent clinical observations about the impact of paricalcitol on serum Ca.
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Affiliation(s)
- J Ruth Wu-Wong
- Department of Pharmacy Practice, University of Illinois at Chicago, Chicago, IL 60612-7230, USA.
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88
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Yuan Q, Sato T, Densmore M, Saito H, Schüler C, Erben RG, Lanske B. Deletion of PTH rescues skeletal abnormalities and high osteopontin levels in Klotho-/- mice. PLoS Genet 2012; 8:e1002726. [PMID: 22615584 PMCID: PMC3355080 DOI: 10.1371/journal.pgen.1002726] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 04/05/2012] [Indexed: 01/16/2023] Open
Abstract
Maintenance of normal mineral ion homeostasis is crucial for many biological activities, including proper mineralization of the skeleton. Parathyroid hormone (PTH), Klotho, and FGF23 have been shown to act as key regulators of serum calcium and phosphate homeostasis through a complex feedback mechanism. The phenotypes of Fgf23−/− and Klotho−/− (Kl−/−) mice are very similar and include hypercalcemia, hyperphosphatemia, hypervitaminosis D, suppressed PTH levels, and severe osteomalacia/osteoidosis. We recently reported that complete ablation of PTH from Fgf23−/− mice ameliorated the phenotype in Fgf23−/−/PTH−/− mice by suppressing serum vitamin D and calcium levels. The severe osteomalacia in Fgf23−/− mice, however, persisted, suggesting that a different mechanism is responsible for this mineralization defect. In the current study, we demonstrate that deletion of PTH from Kl−/− (Kl−/−/PTH−/− or DKO) mice corrects the abnormal skeletal phenotype. Bone turnover markers are restored to wild-type levels; and, more importantly, the skeletal mineralization defect is completely rescued in Kl−/−/PTH−/− mice. Interestingly, the correction of the osteomalacia is accompanied by a reduction in the high levels of osteopontin (Opn) in bone and serum. Such a reduction in Opn levels could not be observed in Fgf23−/−/PTH−/− mice, and these mice showed sustained osteomalacia. This significant in vivo finding is corroborated by in vitro studies using calvarial osteoblast cultures that show normalized Opn expression and rescued mineralization in Kl−/−/PTH−/− mice. Moreover, continuous PTH infusion of Kl−/− mice significantly increased Opn levels and osteoid volume, and decreased trabecular bone volume. In summary, our results demonstrate for the first time that PTH directly impacts the mineralization disorders and skeletal deformities of Kl−/−, but not of Fgf23−/− mice, possibly by regulating Opn expression. These are significant new perceptions into the role of PTH in skeletal and disease processes and suggest FGF23-independent interactions of PTH with Klotho. Maintenance of normal mineral ion homeostasis is crucial for many biological activities, including proper mineralization of the skeleton. PTH, Klotho, and FGF23 are the key regulators of blood mineral ion homeostasis. Klotho is a type-I membrane protein and has been identified as cofactor required for FGF23 to bind and activate its receptor. Loss of either Klotho or Fgf23 activity results in a similar abnormal phenotype, including severe defects in skeletal mineralization and alterations in mineral ion balance. Here we describe a new mouse model in which we eliminated PTH from Kl−/− mice, and we can show that the skeletal mineralization defect was completely rescued in Kl−/−/PTH−/− mice and that this phenomenon was accompanied by a reduction in the high levels of osteopontin in bone and serum. We also present additional data showing that continuous infusion of Kl−/− mice with PTH results in an elevation in Opn levels and subsequently increased osteoid volume. Interestingly, this result differs from our previous report in which we describe that the osteomalacia and the high Opn levels in Fgf23−/−/PTH−/− mice persisted. Our finding suggests that PTH, possibly by regulating osteopontin, is responsible for the skeletal mineralization defect in Kl−/− mice, but not in Fgf23−/− mice.
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Affiliation(s)
- Quan Yuan
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China
| | - Tadatoshi Sato
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Michael Densmore
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Hiroaki Saito
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Christiane Schüler
- Institute of Physiology, Pathophysiology, and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Reinhold G. Erben
- Institute of Physiology, Pathophysiology, and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Beate Lanske
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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Viaene L, Meijers BKI, Vanrenterghem Y, Evenepoel P. Evidence in favor of a severely impaired net intestinal calcium absorption in patients with (early-stage) chronic kidney disease. Am J Nephrol 2012; 35:434-41. [PMID: 22538635 DOI: 10.1159/000338299] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 03/25/2012] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Calcium and phosphorus are essential to many vital physiological processes. Little is known about the net and fractional intestinal absorption of calcium and phosphorus in patients with chronic kidney disease (CKD) and their clinical and hormonal determinants. METHODS Blood and 24-hour urine samples were collected in 20 healthy volunteers (HV) and 72 stable CKD stage 1-4 patients and analyzed for parameters of mineral metabolism including calcidiol, calcitriol, and parathyroid hormone (PTH). Dietary intake was assessed by dietary history. RESULTS The 24-hour urinary calcium excretion, as opposed to the phosphorus excretion, showed a stepwise decrease across CKD stages (median of 219, 84, 40, and 22 mg/day in HV and patients with CKD stages 1-2, 3 and 4, respectively). Younger age, high serum calcitriol, and high estimated GFR were associated with a high 24-hour urinary calcium excretion. High serum calcitriol levels and dietary phosphorus intake were associated with a high 24-hour urinary phosphorus excretion. The fractional intestinal calcium absorption, as estimated by the urinary-to-ingested calcium ratio, decreased across CKD stages. CONCLUSIONS The 24-hour urinary excretion of calcium, as opposed to phosphorus, is markedly decreased in CKD, even in early-stage disease. This is partly explained by low calcitriol levels and older age. Assuming a neutral calcium balance at the time of urine collection, we infer that net intestinal calcium absorption may be severely impaired in CKD.
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Affiliation(s)
- L Viaene
- Division of Nephrology, Dialysis and Renal Transplantation, Department of Medicine, University Hospital Leuven, Leuven, Belgium
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90
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Khuituan P, Teerapornpuntakit J, Wongdee K, Suntornsaratoon P, Konthapakdee N, Sangsaksri J, Sripong C, Krishnamra N, Charoenphandhu N. Fibroblast growth factor-23 abolishes 1,25-dihydroxyvitamin D₃-enhanced duodenal calcium transport in male mice. Am J Physiol Endocrinol Metab 2012; 302:E903-13. [PMID: 22275752 DOI: 10.1152/ajpendo.00620.2011] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Despite being widely recognized as the important bone-derived phosphaturic hormone, whether fibroblast growth factor (FGF)-23 modulated intestinal calcium absorption remained elusive. Since FGF-23 could reduce the circulating level of 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃], FGF-23 probably compromised the 1,25(OH)₂D₃-induced intestinal calcium absorption. FGF-23 may also exert an inhibitory action directly through FGF receptors (FGFR) in the intestinal cells. Herein, we demonstrated by Ussing chamber technique that male mice administered 1 μg/kg 1,25(OH)₂D₃ sc daily for 3 days exhibited increased duodenal calcium absorption, which was abolished by concurrent intravenous injection of recombinant mouse FGF-23. This FGF-23 administration had no effect on the background epithelial electrical properties, i.e., short-circuit current, transepithelial potential difference, and resistance. Immunohistochemical evidence of protein expressions of FGFR isoforms 1-4 in mouse duodenal epithelial cells suggested a possible direct effect of FGF-23 on the intestine. This was supported by the findings that FGF-23 directly added to the serosal compartment of the Ussing chamber and completely abolished the 1,25(OH)₂D₃-induced calcium absorption in the duodenal tissues taken from the 1,25(OH)₂D₃-treated mice. However, direct FGF-23 exposure did not decrease the duodenal calcium absorption without 1,25(OH)₂D₃ preinjection. The observed FGF-23 action was mediated by MAPK/ERK, p38 MAPK, and PKC. Quantitative real-time PCR further showed that FGF-23 diminished the 1,25(OH)₂D₃-induced upregulation of TRPV5, TRPV6, and calbindin-D(9k), but not PMCA(1b) expression in the duodenal epithelial cells. In conclusion, besides being a phosphatonin, FGF-23 was shown to be a novel calcium-regulating hormone that acted directly on the mouse intestine, thereby compromising the 1,25(OH)₂D₃-induced calcium absorption.
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Affiliation(s)
- Pissared Khuituan
- Center of Calcium and Bone Research, Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
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91
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Carlberg C, Molnár F, Mouriño A. Vitamin D receptor ligands: the impact of crystal structures. Expert Opin Ther Pat 2012; 22:417-35. [PMID: 22449247 DOI: 10.1517/13543776.2012.673590] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION In the past years, the biologically active form of vitamin D(3), 1α,25-dihydroxyvitamin D(3) (1α,25(OH)(2)D(3)), has received large appreciation due to the broad physiological impact of the hormone and its nuclear receptor, the transcription factor vitamin D receptor (VDR). Recently, the understanding of VDR actions has progressed greatly, due to VDR crystal structures with various ligands. AREAS COVERED This review will present and discuss new synthetic agonistic and antagonistic 1α,25(OH)(2)D(3) analogs in the context of the recent insights provided by VDR crystal structures. EXPERT OPINION During the last 5 years, a large number of new 1α,25(OH)(2)D(3) analogs, many of which have an interesting functional profile, have been patented. Moreover, for a surprisingly high number of 1α,25(OH)(2)D(3) analogs, the crystal structure data of their complex with the VDR is available. This structural information provides important insight into the functional potential of the VDR ligands and explains their agonistic and antagonistic action. However, so far, only for a few VDR ligands, a rational design, based on crystal structure information, has been applied. The design of future analogs may also take the specificity of co-factor interaction into account, in order to create selective VDR modulators.
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Affiliation(s)
- Carsten Carlberg
- University of Eastern Finland, School of Medicine, Institute of Biomedicine, Kuopio, Finland.
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92
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Riccardi D, Kemp PJ. The Calcium-Sensing Receptor Beyond Extracellular Calcium Homeostasis: Conception, Development, Adult Physiology, and Disease. Annu Rev Physiol 2012; 74:271-97. [DOI: 10.1146/annurev-physiol-020911-153318] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Daniela Riccardi
- Division of Pathophysiology and Repair, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, United Kingdom; ,
| | - Paul J. Kemp
- Division of Pathophysiology and Repair, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, United Kingdom; ,
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Haussler MR, Whitfield GK, Kaneko I, Forster R, Saini R, Hsieh JC, Haussler CA, Jurutka PW. The role of vitamin D in the FGF23, klotho, and phosphate bone-kidney endocrine axis. Rev Endocr Metab Disord 2012; 13:57-69. [PMID: 21932165 PMCID: PMC3288475 DOI: 10.1007/s11154-011-9199-8] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
1,25-dihydroxyvitamin D (1,25D), through association with the nuclear vitamin D receptor (VDR), exerts control over a novel endocrine axis consisting of the bone-derived hormone FGF23, and the kidney-expressed klotho, CYP27B1, and CYP24A1 genes, which together prevent hyperphosphatemia/ectopic calcification and govern the levels of 1,25D to maintain bone mineral integrity while promoting optimal function of other vital tissues. When occupied by 1,25D, VDR interacts with RXR to form a heterodimer that binds to VDREs in the region of genes directly controlled by 1,25D (e.g., FGF23, klotho, Npt2c, CYP27B1 and CYP24A1). By recruiting complexes of comodulators, activated VDR initiates a series of events that induces or represses the transcription of genes encoding proteins such as: the osteocyte-derived hormone, FGF23; the renal anti-senescence factor and protein co-receptor for FGF23, klotho; other mediators of phosphate transport including Npt2a/c; and vitamin D hormone metabolic enzymes, CYP27B1 and CYP24A1. The mechanism whereby osteocytes are triggered to release FGF23 is yet to be fully defined, but 1,25D, phosphate, and leptin appear to play major roles. The kidney responds to FGF23 to elicit CYP24A1-catalyzed detoxification of the 1,25D hormone while also repressing both Npt2a/c to mediate phosphate elimination and CYP27B1 to limit de novo 1,25D synthesis. Comprehension of these skeletal and renal actions of 1,25D should facilitate the development of novel mimetics to prevent ectopic calcification, chronic renal and vascular disease, and promote healthful aging.
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Affiliation(s)
- Mark R Haussler
- Department of Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA.
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Pan W, Borovac J, Spicer Z, Hoenderop JG, Bindels RJ, Shull GE, Doschak MR, Cordat E, Alexander RT. The epithelial sodium/proton exchanger, NHE3, is necessary for renal and intestinal calcium (re)absorption. Am J Physiol Renal Physiol 2011; 302:F943-56. [PMID: 21937605 DOI: 10.1152/ajprenal.00504.2010] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Passive paracellular proximal tubular (PT) and intestinal calcium (Ca(2+)) fluxes have been linked to active sodium (re)absorption. Although the epithelial sodium/proton exchanger, NHE3, mediates apical sodium entry at both these sites, its role in Ca(2+) homeostasis remains unclear. We, therefore, set out to determine whether NHE3 is necessary for Ca(2+) (re)absorption from these epithelia by comparing Ca(2+) handling between wild-type and NHE3(-/-) mice. Serum Ca(2+) and plasma parathyroid hormone levels were not different between groups. However, NHE3(-/-) mice had increased serum 1,25-dihydroxyvitamin D(3). The fractional excretion of Ca(2+) was also elevated in NHE3(-/-) mice. Paracellular Ca(2+) flux across confluent monolayers of a PT cell culture model was increased by an osmotic gradient equivalent to that generated by NHE3 across the PT in vivo and by overexpression of NHE3.( 45)Ca(2+) uptake after oral gavage and flux studies in Ussing chambers across duodenum of wild-type and NHE3(-/-) mice confirmed decreased Ca(2+) absorption in NHE3(-/-) mice compared with wild-type mice. Consistent with this, intestinal calbindin-D(9K), claudin-2, and claudin-15 mRNA expression was decreased. Microcomputed tomography analysis revealed a perturbation in bone mineralization. NHE3(-/-) mice had both decreased cortical bone mineral density and trabecular bone mass. Our results demonstrate significant alterations of Ca(2+) homeostasis in NHE3(-/-) mice and provide a molecular link between Na(+) and Ca(2+) (re)absorption.
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Affiliation(s)
- Wanling Pan
- Division of Nephrology, Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
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95
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Shanahan CM, Crouthamel MH, Kapustin A, Giachelli CM. Arterial calcification in chronic kidney disease: key roles for calcium and phosphate. Circ Res 2011; 109:697-711. [PMID: 21885837 PMCID: PMC3249146 DOI: 10.1161/circresaha.110.234914] [Citation(s) in RCA: 671] [Impact Index Per Article: 51.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Vascular calcification contributes to the high risk of cardiovascular mortality in chronic kidney disease (CKD) patients. Dysregulation of calcium (Ca) and phosphate (P) metabolism is common in CKD patients and drives vascular calcification. In this article, we review the physiological regulatory mechanisms for Ca and P homeostasis and the basis for their dysregulation in CKD. In addition, we highlight recent findings indicating that elevated Ca and P have direct effects on vascular smooth muscle cells (VSMCs) that promote vascular calcification, including stimulation of osteogenic/chondrogenic differentiation, vesicle release, apoptosis, loss of inhibitors, and extracellular matrix degradation. These studies suggest a major role for elevated P in promoting osteogenic/chondrogenic differentiation of VSMC, whereas elevated Ca has a predominant role in promoting VSMC apoptosis and vesicle release. Furthermore, the effects of elevated Ca and P are synergistic, providing a major stimulus for vascular calcification in CKD. Unraveling the complex regulatory pathways that mediate the effects of both Ca and P on VSMCs will ultimately provide novel targets and therapies to limit the destructive effects of vascular calcification in CKD patients.
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Abstract
Tumor-induced osteomalacia (TIO) is a rare and fascinating paraneoplastic syndrome in which patients present with bone pain, fractures, and muscle weakness. The cause is high blood levels of the recently identified phosphate and vitamin D-regulating hormone, fibroblast growth factor 23 (FGF23). In TIO, FGF23 is secreted by mesenchymal tumors that are usually benign, but are typically very small and difficult to locate. FGF23 acts primarily at the renal tubule and impairs phosphate reabsorption and 1α-hydroxylation of 25-hydroxyvitamin D, leading to hypophosphatemia and low levels of 1,25-dihydroxy vitamin D. A step-wise approach utilizing functional imaging (F-18 fluorodeoxyglucose positron emission tomography and octreotide scintigraphy) followed by anatomical imaging (computed tomography and/or magnetic resonance imaging), and, if needed, selective venous sampling with measurement of FGF23 is usually successful in locating the tumors. For tumors that cannot be located, medical treatment with phosphate supplements and active vitamin D (calcitriol or alphacalcidiol) is usually successful; however, the medical regimen can be cumbersome and associated with complications. This review summarizes the current understanding of the pathophysiology of the disease and provides guidance in evaluating and treating these patients. Novel imaging modalities and medical treatments, which hold promise for the future, are also reviewed.
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Affiliation(s)
- William H Chong
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, Hatfield Clinical Research Center, National Institutes of Health, Bethesda, Maryland 20892, USA
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97
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Ghishan FK, Kiela PR. Advances in the understanding of mineral and bone metabolism in inflammatory bowel diseases. Am J Physiol Gastrointest Liver Physiol 2011; 300:G191-201. [PMID: 21088237 PMCID: PMC3043650 DOI: 10.1152/ajpgi.00496.2010] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 11/11/2010] [Indexed: 02/08/2023]
Abstract
Chronic inflammatory disorders such as inflammatory bowel diseases (IBDs) affect bone metabolism and are frequently associated with the presence of osteopenia, osteoporosis, and increased risk of fractures. Although several mechanisms may contribute to skeletal abnormalities in IBD patients, inflammation and inflammatory mediators such as TNF, IL-1β, and IL-6 may be the most critical. It is not clear whether the changes in bone metabolism leading to decreased mineral density are the result of decreased bone formation, increased bone resorption, or both, with varying results reported in experimental models of IBD and in pediatric and adult IBD patients. New data, including our own, challenge the conventional views, and contributes to the unraveling of an increasingly complex network of interactions leading to the inflammation-associated bone loss. Since nutritional interventions (dietary calcium and vitamin D supplementation) are of limited efficacy in IBD patients, understanding the pathophysiology of osteopenia and osteoporosis in Crohn's disease and ulcerative colitis is critical for the correct choice of available treatments or the development of new targeted therapies. In this review, we discuss current concepts explaining the effects of inflammation, inflammatory mediators and their signaling effectors on calcium and phosphate homeostasis, osteoblast and osteoclast function, and the potential limitations of vitamin D used as an immunomodulator and anabolic hormone in IBD.
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Affiliation(s)
- Fayez K Ghishan
- Dept. of Pediatrics, Steele Children's Research Center, Univ. of Arizona Health Sciences Center; 1501 N. Campbell Ave., Tucson, AZ 85724, USA
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98
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Khoshniat S, Bourgine A, Julien M, Weiss P, Guicheux J, Beck L. The emergence of phosphate as a specific signaling molecule in bone and other cell types in mammals. Cell Mol Life Sci 2011; 68:205-18. [PMID: 20848155 PMCID: PMC11114507 DOI: 10.1007/s00018-010-0527-z] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 08/02/2010] [Accepted: 08/31/2010] [Indexed: 02/07/2023]
Abstract
Although considerable advances in our understanding of the mechanisms of phosphate homeostasis and skeleton mineralization have recently been made, little is known about the initial events involving the detection of changes in the phosphate serum concentrations and the subsequent downstream regulation cascade. Recent data has strengthened a long-established hypothesis that a phosphate-sensing mechanism may be present in various organs. Such a phosphate sensor would detect changes in serum or local phosphate concentration and would inform the body, the local environment, or the individual cell. This suggests that phosphate in itself could represent a signal regulating multiple factors necessary for diverse biological processes such as bone or vascular calcification. This review summarizes findings supporting the possibility that phosphate represents a signaling molecule, particularly in bone and cartilage, but also in other tissues. The involvement of various signaling pathways (ERK1/2), transcription factors (Fra-1, Runx2) and phosphate transporters (PiT1, PiT2) is discussed.
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Affiliation(s)
- Solmaz Khoshniat
- Group STEP (Skeletal Tissue Engineering and Physiopathology), Centre for Osteoarticular and Dental Tissue Engineering (LIOAD), INSERM, U791, 44042 Nantes, France
- UFR Odontologie, Pres UNAM, 44042 Nantes, France
| | - Annabelle Bourgine
- Group STEP (Skeletal Tissue Engineering and Physiopathology), Centre for Osteoarticular and Dental Tissue Engineering (LIOAD), INSERM, U791, 44042 Nantes, France
- UFR Odontologie, Pres UNAM, 44042 Nantes, France
| | - Marion Julien
- Group STEP (Skeletal Tissue Engineering and Physiopathology), Centre for Osteoarticular and Dental Tissue Engineering (LIOAD), INSERM, U791, 44042 Nantes, France
- UFR Odontologie, Pres UNAM, 44042 Nantes, France
| | - Pierre Weiss
- Group STEP (Skeletal Tissue Engineering and Physiopathology), Centre for Osteoarticular and Dental Tissue Engineering (LIOAD), INSERM, U791, 44042 Nantes, France
- UFR Odontologie, Pres UNAM, 44042 Nantes, France
| | - Jérôme Guicheux
- Group STEP (Skeletal Tissue Engineering and Physiopathology), Centre for Osteoarticular and Dental Tissue Engineering (LIOAD), INSERM, U791, 44042 Nantes, France
- UFR Odontologie, Pres UNAM, 44042 Nantes, France
| | - Laurent Beck
- Growth and Signalling Research Center, INSERM, U845, 75015 Paris, France
- Faculté de Médecine, Centre de Recherche, INSERM U845, Université Paris Descartes, 156 Rue de Vaugirard, 75015 Paris, France
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99
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Affiliation(s)
- Kyle Brizendine
- Department of Internal Medicine, University of Alabama School of Medicine, Birmingham, Alabama 35294-3407, USA
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100
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Haussler MR, Haussler CA, Whitfield GK, Hsieh JC, Thompson PD, Barthel TK, Bartik L, Egan JB, Wu Y, Kubicek JL, Lowmiller CL, Moffet EW, Forster RE, Jurutka PW. The nuclear vitamin D receptor controls the expression of genes encoding factors which feed the "Fountain of Youth" to mediate healthful aging. J Steroid Biochem Mol Biol 2010; 121:88-97. [PMID: 20227497 PMCID: PMC2906618 DOI: 10.1016/j.jsbmb.2010.03.019] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Accepted: 03/08/2010] [Indexed: 12/13/2022]
Abstract
The nuclear vitamin D receptor (VDR) binds 1,25-dihydroxyvitamin D3 (1,25D), its high affinity renal endocrine ligand, to signal intestinal calcium and phosphate absorption plus bone remodeling, generating a mineralized skeleton free of rickets/osteomalacia with a reduced risk of osteoporotic fractures. 1,25D/VDR signaling regulates the expression of TRPV6, BGP, SPP1, LRP5, RANKL and OPG, while achieving feedback control of mineral ions to prevent age-related ectopic calcification by governing CYP24A1, PTH, FGF23, PHEX, and klotho transcription. Vitamin D also elicits numerous intracrine actions when circulating 25-hydroxyvitamin D3, the metabolite reflecting vitamin D status, is converted to 1,25D locally by extrarenal CYP27B1, and binds VDR to promote immunoregulation, antimicrobial defense, xenobiotic detoxification, anti-inflammatory/anticancer actions and cardiovascular benefits. VDR also affects Wnt signaling through direct interaction with beta-catenin, ligand-dependently blunting beta-catenin mediated transcription in colon cancer cells to attenuate growth, while potentiating beta-catenin signaling via VDR ligand-independent mechanisms in osteoblasts and keratinocytes to function osteogenically and as a pro-hair cycling receptor, respectively. Finally, VDR also drives the mammalian hair cycle in conjunction with the hairless corepressor by repressing SOSTDC1, S100A8/S100A9, and PTHrP. Hair provides a shield against UV-induced skin damage and cancer in terrestrial mammals, illuminating another function of VDR that facilitates healthful aging.
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Affiliation(s)
- Mark R Haussler
- Department of Basic Medical Sciences, The University of Arizona, College of Medicine-Phoenix in partnership with Arizona State University, Phoenix, AZ 85004-2157, United States.
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