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Verlinden L, Li S, Veldurthy V, Carmeliet G, Christakos S. Relationship of the bone phenotype of the Klotho mutant mouse model of accelerated aging to changes in skeletal architecture that occur with chronological aging. Front Endocrinol (Lausanne) 2024; 15:1310466. [PMID: 38352710 PMCID: PMC10861770 DOI: 10.3389/fendo.2024.1310466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 01/09/2024] [Indexed: 02/16/2024] Open
Abstract
Introduction Due to the relatively long life span of rodent models, in order to expediate the identification of novel therapeutics of age related diseases, mouse models of accelerated aging have been developed. In this study we examined skeletal changes in the male and female Klotho mutant (kl/kl) mice and in male and female chronically aged mice to determine whether the accelerated aging bone phenotype of the kl/kl mouse reflects changes in skeletal architecture that occur with chronological aging. Methods 2, 6 and 20-23 month old C57BL/6 mice were obtained from the National Institute of Aging aged rodent colony and wildtype and kl/kl mice were generated as previously described by M. Kuro-o. Microcomputed tomography analysis was performed ex vivo to examine trabecular and cortical parameters from the proximal metaphyseal and mid-diaphyseal areas, respectively. Serum calcium and phosphate were analyzed using a colorimetric assay. The expression of duodenal Trpv6, which codes for TRPV6, a vitamin D regulated epithelial calcium channel whose expression reflects intestinal calcium absorptive efficiency, was analyzed by quantitative real-time PCR. Results and discussion Trabecular bone volume (BV/TV) and trabecular number decreased continuously with age in males and females. In contrast to aging mice, an increase in trabecular bone volume and trabecular number was observed in both male and female kl/kl mice. Cortical thickness decreased with advancing age and also decreased in male and female kl/kl mice. Serum calcium and phosphate levels were significantly increased in kl/kl mice but did not change with age. Aging resulted in a decline in Trpv6 expression. In the kl/kl mice duodenal Trpv6 was significantly increased. Our findings reflect differences in bone architecture as well as differences in calcium and phosphate homeostasis and expression of Trpv6 between the kl/kl mutant mouse model of accelerated aging and chronological aging. Although the Klotho deficient mouse has provided a new understanding of the regulation of mineral homeostasis and bone metabolism, our findings suggest that changes in bone architecture in the kl/kl mouse reflect in part systemic disturbances that differ from pathophysiological changes that occur with age including dysregulation of calcium homeostasis that contributes to age related bone loss.
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Affiliation(s)
- Lieve Verlinden
- Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Shanshan Li
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers, the State University of New Jersey, Newark, NJ, United States
| | - Vaishali Veldurthy
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers, the State University of New Jersey, Newark, NJ, United States
| | - Geert Carmeliet
- Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Sylvia Christakos
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers, the State University of New Jersey, Newark, NJ, United States
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Hilma RF, Widaty S, Marissa M, Ilyas M. Association between serum level of vitamin D (25-hydroxyvitamin D) and plasma level of vitamin D receptor with bacteriological index in leprosy patients. Dermatol Reports 2023; 15:9705. [PMID: 38327594 PMCID: PMC10848641 DOI: 10.4081/dr.2023.9705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 04/23/2023] [Indexed: 02/09/2024] Open
Abstract
Macrophages respond against Mycobacterium leprae infection through interacting with vitamin D and vitamin D receptor (VDR). There has been no study analyzing the association between vitamin D and VDR with bacteriological index (BI) in leprosy patients in Indonesia. To analyze the serum level of 25- hydroxyvitamin D (25(OH)D) and plasma level of VDR as well as their association with BI in leprosy patients in Indonesia. This is a cross-sectional study. Serum level of 25(OH)D was assessed with in vitro chemiluminescent immunoassay. Plasma level of VDR was assessed with enzyme linked immunosorbent assay method. Median serum level of 25(OH)D was 12.68 ng/mL. There was no correlation between serum level of 25(OH)D and BI (r=0.033; p=0.869). Median plasma level of VDR was 1.36 ng/mL. There was no correlation between plasma level of VDR and BI (r=- 0.063; p=0.749) and no significant association between BI and serum level of 25(OH) and plasma level of VDR (R2=0.055). There was no association between serum level of 25(OH)D and plasma level of VDR with BI in leprosy patients.
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Affiliation(s)
- Rizka Farah Hilma
- Department of Dermatology and Venereology, Faculty of Medicine Universitas Indonesia, Dr. Cipto Mangunkusumo National Hospital, Jakarta
| | - Sandra Widaty
- Department of Dermatology and Venereology, Faculty of Medicine Universitas Indonesia, Dr. Cipto Mangunkusumo National Hospital, Jakarta
| | - Melani Marissa
- Department of Dermatology and Venereology, Faculty of Medicine Universitas Indonesia, Dr. Cipto Mangunkusumo National Hospital, Jakarta
| | - Muhammad Ilyas
- Department of Community Medical Science, Faculty of Medicine Universitas Indonesia, Jakarta, Indonesia
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Harahap IA, Kuligowski M, Schmidt M, Kołodziejski PA, Suliburska J. Effects of isoflavone and probiotic intake on calcium transport and bone metabolism biomarkers in female rats. Food Sci Nutr 2023; 11:6324-6335. [PMID: 37823105 PMCID: PMC10563734 DOI: 10.1002/fsn3.3571] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/15/2023] [Accepted: 07/09/2023] [Indexed: 10/13/2023] Open
Abstract
Calcium is essential for maintaining bone health as it contributes to bone formation, remodeling, strength, and density. This study investigated the effect of isoflavones and probiotics on calcium transporters' gene expression, serum calcium levels, and bone metabolism biomarkers in healthy female rats. Forty-eight female Wistar rats were classified into six groups. Bone metabolism biomarkers (pyridinoline, deoxypyridinoline, parathyroid hormone, and osteocalcin) and serum calcium levels were measured by enzyme-linked immunosorbent assay (ELISA) and atomic absorption spectroscopy (AAS), respectively. Gene expression of calcium transporters (Trpv5 and Trpv6) was evaluated in duodenum and jejunum tissue samples using quantitative polymerase chain reaction (qPCR). Trpv5 and Trpv6, epithelial calcium channels, play a crucial role in calcium transport and homeostasis in the body. The study consisted of a1-week adaptation period for the rats to adjust to the controlled conditions, followed by an 8-week intervention phase. The daidzein and genistein group showed a significant increase in the gene expression of the Trpv6 transporter in the duodenum and a marked decrease in serum pyridinoline levels compared to the control group. The tempeh and soybean groups showed a significant decrease in the gene expression of the Trpv5 calcium transporter in the jejunum. However, no significant influence of the Lactobacillus acidophilus diet on calcium transport and bone metabolism biomarkers was observed in the L. acidophilus group. The correlation analysis showed a significant positive relationship between serum calcium, bone metabolism biomarkers, and calcium transporters. In conclusion, our study demonstrates that the daidzein and genistein diet improves calcium transport in the duodenum and reduces pyridinoline serum concentrations, while tempeh and soybean diets reduce calcium transport in the jejunum. However, the combination of daidzein, genistein, and L. acidophilus did not demonstrate a synergistic effect on calcium transport and bone metabolism, suggesting that further investigations are needed to elucidate their potential interactions.
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Affiliation(s)
- Iskandar Azmy Harahap
- Department of Human Nutrition and Dietetics, Faculty of Food Science and NutritionPoznan University of Life SciencesPoznanPoland
| | - Maciej Kuligowski
- Department of Food Technology of Plant Origin, Faculty of Food Science and NutritionPoznan University of Life SciencesPoznanPoland
| | - Marcin Schmidt
- Department of Biotechnology and Food Microbiology, Faculty of Food Science and NutritionPoznan University of Life SciencesPoznanPoland
| | - Paweł A. Kołodziejski
- Department of Animal Physiology, Biochemistry and Biostructure, Faculty of Veterinary Medicine and Animal SciencePoznań University of Life SciencesPoznanPoland
| | - Joanna Suliburska
- Department of Human Nutrition and Dietetics, Faculty of Food Science and NutritionPoznan University of Life SciencesPoznanPoland
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Jiang H, Chanpaisaeng K, Christakos S, Fleet JC. Intestinal Vitamin D Receptor Is Dispensable for Maintaining Adult Bone Mass in Mice With Adequate Calcium Intake. Endocrinology 2023; 164:bqad051. [PMID: 36960562 PMCID: PMC10282920 DOI: 10.1210/endocr/bqad051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 03/03/2023] [Accepted: 03/22/2023] [Indexed: 03/25/2023]
Abstract
1,25-Dihydroxyvitamin D3 (1,25(OH)2D3)-mediated intestinal calcium (Ca) absorption supplies Ca for proper bone mineralization during growth. We tested whether vitamin D receptor (VDR)-mediated 1,25(OH)2D3 signaling is critical for adult Ca absorption and bone by using mice with inducible Vdr gene knockout in the whole intestine (villin-CreERT2+/- × Vdrf/f, WIK) or in the large intestine (Cdx2-CreERT2+/- ×Vdrf/f, LIK). At 4-month-old, Vdr alleles were recombined (0.05 mg tamoxifen/g BW, intraperitoneally [i.p.], 5 days) and mice were fed diets with either 0.5% (adequate) or 0.2% (low) Ca. Ca absorption was examined after 2 weeks while serum 1,25(OH)2D3, bone mass, and bone microarchitecture were examined after 16 weeks. Intestinal and renal gene expression was measured at both time points (n = 12/genotype/diet/time point). On the 0.5% Ca diet, all phenotypes in WIK and LIK mice were similar to the controls. Control mice adapted to the 0.2% low-Ca diet by increasing renal Cyp27b1 mRNA (3-fold), serum 1,25(OH)2D3 level (1.9-fold), and Ca absorption in the duodenum (Dd, + 131%) and proximal colon (PCo, + 28.9%), which prevented bone loss. In WIK mice, low-Ca diet increased serum 1,25(OH)2D3 (4.4-fold) but Ca absorption remained unaltered in the Dd and PCo. Consequently, significant bone loss occurred in WIK mice (e.g., cortical thickness, Ct.Th, -33.7%). LIK mice adapted to the low-Ca diet in the Dd but not the PCo, and the effect on bone phenotypes was milder (e.g., Ct.Th, -13.1%). Our data suggest intestinal VDR in adult mice prevents bone loss under low Ca intake but is dispensable under adequate calcium intake.
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Affiliation(s)
- Heng Jiang
- Department of Nutritional Sciences, Dell Pediatric Research Institute, University of Texas, Austin, TX 78723, USA
| | - Krittikan Chanpaisaeng
- Functional Ingredients and Food Innovation Research Group, National Center for Genetic Engineering and Biotechnology, Pathum Thani 12120, Thailand
| | - Sylvia Christakos
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
| | - James C Fleet
- Department of Nutritional Sciences, Dell Pediatric Research Institute, University of Texas, Austin, TX 78723, USA
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Suzuki K, Tsujiguchi H, Hara A, Miyagi S, Nguyen TTT, Kambayashi Y, Shimizu Y, Suzuki F, Takazawa C, Nakamura M, Tsuboi H, Kannon T, Tajima A, Nakamura H. Bone Strength of the Calcaneus Is Associated with Dietary Calcium Intake in Older Japanese Men, but Not Women. Nutrients 2022; 14:nu14245225. [PMID: 36558384 PMCID: PMC9781445 DOI: 10.3390/nu14245225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 11/25/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
The relationship between calcium intake and bone strength in older Asian individuals, including Japanese, is controversial; therefore, we herein investigated this relationship in older Japanese populations. We performed a cross-sectional analysis of 314 participants older than 65 years who voluntarily participated in a medical examination and responded to questionnaires. The osteo-sono assessment index (OSI) measured at the right calcaneus using a quantitative ultrasonic device was used as an indicator of bone strength. The daily dietary intake of calcium was assessed using a brief-type self-administered diet history questionnaire. A two-way analysis of covariance revealed a significant interaction between sex and calcium intake on the OSI (p < 0.01). A multiple regression analysis showed a positive correlation between calcium intake and the OSI in males (p < 0.01), but not females (p = 0.27). In females, grip strength divided by body weight positively correlated with the OSI (p = 0.04). The present results suggest that a higher calcium intake contributes to bone strength in older Japanese males. Although a higher grip strength may contribute to bone strength in females, the potential of estrogen as a confounding factor needs to be considered.
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Affiliation(s)
- Keita Suzuki
- Department of Hygiene and Public Health, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
- Correspondence: ; Tel.: +81-76-265-2218
| | - Hiromasa Tsujiguchi
- Department of Hygiene and Public Health, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
- Department of Public Health, Graduate School of Advanced Preventive Medical Sciences, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
- Kanazawa University Advanced Preventive Medical Sciences Research Center, Kanazawa 920-8640, Ishikawa, Japan
| | - Akinori Hara
- Department of Hygiene and Public Health, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
- Department of Public Health, Graduate School of Advanced Preventive Medical Sciences, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
- Kanazawa University Advanced Preventive Medical Sciences Research Center, Kanazawa 920-8640, Ishikawa, Japan
| | - Sakae Miyagi
- Kanazawa University Advanced Preventive Medical Sciences Research Center, Kanazawa 920-8640, Ishikawa, Japan
- Innovative Clinical Research Center, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
| | - Thao Thi Thu Nguyen
- Department of Epidemiology, Faculty of Public Health, Haiphong University of Medicine and Pharmacy, Hai Phong 04000-05000, Vietnam
| | - Yasuhiro Kambayashi
- Department of Public Health, Faculty of Veterinary Medicine, Okayama University of Science, Imabari 794-0085, Ehime, Japan
| | - Yukari Shimizu
- Department of Nursing, Faculty of Health Sciences, Komatsu University, Komatsu 923-8511, Ishikawa, Japan
| | - Fumihiko Suzuki
- Department of Hygiene and Public Health, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
- Community Medicine Support Dentistry, Ohu University Hospital, Koriyama 963-8611, Fukushima, Japan
| | - Chie Takazawa
- Department of Hygiene and Public Health, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
| | - Masaharu Nakamura
- Department of Hygiene and Public Health, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
| | - Hirohito Tsuboi
- Graduate School of Human Nursing, The University of Shiga Prefecture, Hikone 522-8533, Shiga, Japan
| | - Takayuki Kannon
- Department of Biomedical Data Science, School of Medicine, Fujita Health University, Toyoake 470-1101, Aichi, Japan
| | - Atsushi Tajima
- Department of Bioinformatics and Genomics, Graduate School of Advanced Preventive Medical Sciences, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
| | - Hiroyuki Nakamura
- Department of Hygiene and Public Health, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
- Department of Public Health, Graduate School of Advanced Preventive Medical Sciences, Kanazawa University, Kanazawa 920-8640, Ishikawa, Japan
- Kanazawa University Advanced Preventive Medical Sciences Research Center, Kanazawa 920-8640, Ishikawa, Japan
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6
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Vitamin D-Mediated Regulation of Intestinal Calcium Absorption. Nutrients 2022; 14:nu14163351. [PMID: 36014856 PMCID: PMC9416674 DOI: 10.3390/nu14163351] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 11/27/2022] Open
Abstract
Vitamin D is a critical regulator of calcium and bone homeostasis. While vitamin D has multiple effects on bone and calcium metabolism, the regulation of intestinal calcium (Ca) absorption efficiency is a critical function for vitamin D. This is necessary for optimal bone mineralization during growth, the protection of bone in adults, and the prevention of osteoporosis. Intestinal Ca absorption is regulated by 1,25 dihydroxyvitamin D (1,25(OH)2 D), a hormone that activates gene transcription following binding to the intestinal vitamin D receptor (VDR). When dietary Ca intake is low, Ca absorption follows a vitamin-D-regulated, saturable pathway, but when dietary Ca intake is high, Ca absorption is predominately through a paracellular diffusion pathway. Deletion of genes that mediate vitamin D action (i.e., VDR) or production (CYP27B1) eliminates basal Ca absorption and prevents the adaptation of mice to low-Ca diets. Various physiologic or disease states modify vitamin-D-regulated intestinal absorption of Ca (enhanced during late pregnancy, reduced due to menopause and aging).
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Aita R, Aldea D, Hassan S, Hur J, Pellon-Cardenas O, Cohen E, Chen L, Shroyer N, Christakos S, Verzi MP, Fleet JC. Genomic analysis of 1,25-dihydroxyvitamin D 3 action in mouse intestine reveals compartment and segment-specific gene regulatory effects. J Biol Chem 2022; 298:102213. [PMID: 35779631 PMCID: PMC9358460 DOI: 10.1016/j.jbc.2022.102213] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 06/24/2022] [Accepted: 06/25/2022] [Indexed: 01/01/2023] Open
Abstract
1,25-dihydroxyvitamin D (VD) regulates intestinal calcium absorption in the small intestine (SI) and also reduces risk of colonic inflammation and cancer. However, the intestine compartment-specific target genes of VD signaling are unknown. Here, we examined VD action across three functional compartments of the intestine using RNA-seq to measure VD-induced changes in gene expression and Chromatin Immunoprecipitation with next generation sequencing to measure vitamin D receptor (VDR) genomic binding. We found that VD regulated the expression of 55 shared transcripts in the SI crypt, SI villi, and in the colon, including Cyp24a1, S100g, Trpv6, and Slc30a10. Other VD-regulated transcripts were unique to the SI crypt (162 up, 210 down), villi (199 up, 63 down), or colon (102 up, 28 down), but this did not correlate with mRNA levels of the VDR. Furthermore, bioinformatic analysis identified unique VD-regulated biological functions in each compartment. VDR-binding sites were found in 70% of upregulated genes from the colon and SI villi but were less common in upregulated genes from the SI crypt and among downregulated genes, suggesting some transcript-level VD effects are likely indirect. Consistent with this, we show that VD regulated the expression of other transcription factors and their downstream targets. Finally, we demonstrate that compartment-specific VD-mediated gene expression was associated with compartment-specific VDR-binding sites (<30% of targets) and enrichment of intestinal transcription factor-binding motifs within VDR-binding peaks. Taken together, our data reveal unique spatial patterns of VD action in the intestine and suggest novel mechanisms that could account for compartment-specific functions of this hormone.
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Affiliation(s)
- Rohit Aita
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers Cancer Institute of New Jersey, Institute of Food, Nutrition, and Health, EOHSI, Rutgers University, New Jersey, USA
| | - Dennis Aldea
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers Cancer Institute of New Jersey, Institute of Food, Nutrition, and Health, EOHSI, Rutgers University, New Jersey, USA
| | - Sohaib Hassan
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers Cancer Institute of New Jersey, Institute of Food, Nutrition, and Health, EOHSI, Rutgers University, New Jersey, USA
| | - Joseph Hur
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers Cancer Institute of New Jersey, Institute of Food, Nutrition, and Health, EOHSI, Rutgers University, New Jersey, USA
| | - Oscar Pellon-Cardenas
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers Cancer Institute of New Jersey, Institute of Food, Nutrition, and Health, EOHSI, Rutgers University, New Jersey, USA
| | - Evan Cohen
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers Cancer Institute of New Jersey, Institute of Food, Nutrition, and Health, EOHSI, Rutgers University, New Jersey, USA
| | - Lei Chen
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers Cancer Institute of New Jersey, Institute of Food, Nutrition, and Health, EOHSI, Rutgers University, New Jersey, USA
| | - Noah Shroyer
- Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, Texas, USA
| | - Sylvia Christakos
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, New Jersey, USA.
| | - Michael P Verzi
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers Cancer Institute of New Jersey, Institute of Food, Nutrition, and Health, EOHSI, Rutgers University, New Jersey, USA.
| | - James C Fleet
- Department of Nutritional Science, University of Texas, Austin, Texas, USA.
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Regulatory domains controlling high intestinal vitamin D receptor gene expression are conserved in mouse and human. J Biol Chem 2022; 298:101616. [PMID: 35065959 PMCID: PMC8891975 DOI: 10.1016/j.jbc.2022.101616] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 12/14/2022] Open
Abstract
Vitamin D receptor (VDR) levels are highest in the intestine where it mediates 1,25 dihydroxyvitamin D-induced gene expression. However, the mechanisms controlling high intestinal VDR gene expression are unknown. Here, we used Assay for Transposase-Accessible Chromatin using Sequencing (ATAC-Seq) to identify the regulatory sites controlling intestine-specific Vdr gene expression in the small intestine (villi and crypts) and colon of developing, adult, and aged mice. We identified 17 ATAC peaks in a 125 kb region from intron 3 to −55.8 kb from exon 1 of the Vdr gene. Interestingly, many of these peaks were missing/reduced in the developing intestine. Chromatin ImmunoPrecipitation-Sequencing (ChIP-Seq) peaks for intestinal transcription factors (TFs) were present within the ATAC peaks and at HiChIP looping attachments that connected the ATAC/TF ChIP peaks to the transcription start site and CCCTF-binding factor sites at the borders of the Vdr gene regulatory domain. Intestine-specific regulatory sites were identified by comparing ATAC peaks to DNAse-Seq data from other tissues that revealed tissue-specific, evolutionary conserved, and species-specific peaks. Bioinformatics analysis of human DNAse-Seq peaks revealed polymorphisms that disrupt TF-binding sites. Our analysis shows that mouse intestinal Vdr gene regulation requires a complex interaction of multiple distal regulatory regions and is controlled by a combination of intestinal TFs. These intestinal regulatory sites are well conserved in humans suggesting that they may be key components of VDR regulation in both mouse and human intestines.
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Matsuura Y, Morishita T, Sato M, Sumida N, Katayama T, Tsutsumi R, Sakaue H, Taketani Y, Sairyo K, Kawaura A, Takeda E. Effects of daily 1,000-IU vitamin D-fortified milk intake on skeletal muscle mass, power, physical function and nutrition status in Japanese. THE JOURNAL OF MEDICAL INVESTIGATION 2021; 68:249-255. [PMID: 34759139 DOI: 10.2152/jmi.68.249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
An intervention study was conducted to investigate the effects of daily 1,000-IU vitamin D-fortified milk intake on skeletal muscle mass, power, physical function and nutrition status in 26 healthy people and 8 older adults living in a nursing home. The serum 25-hydroxyvitamin D [25(OH)D] level was 13.4 ± 0.8 ng / mL and it markedly increased to 29.6 ± 0.9 ng / mL after daily 1000-IU vitamin D-fortified milk intake for 6 months. Handgrip strength (kg) also significantly increased in the 21-50 years and total groups, and male subjects, and the timed up and go test significantly improved in the 21-50 years and total groups, and female subjects after 6-month vitamin D intake. However, there were no significant differences between baseline and post-treatment in the Barthel Index (BI), walking speed (m / sec) or skeletal muscle mass (kg, % of BW, kg / m2). Therefore, the present study suggested that vitamin D-fortified milk intake is effective at improving muscle strength and physical function in Japanese, although further studies are needed, particularly for older adults. J. Med. Invest. 68 : 249-255, August, 2021.
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Affiliation(s)
- Yasushi Matsuura
- Kenshokai Gakuen College for Health and Welfare, Tokushima, Japan
| | | | - Michiko Sato
- Kenshokai Gakuen College for Health and Welfare, Tokushima, Japan
| | - Nami Sumida
- Kenshokai Gakuen College for Health and Welfare, Tokushima, Japan
| | - Takafumi Katayama
- Department of Statistics and Computer Science, College of Nursing Art and Science, University of Hyogo, Akashi, Japan
| | - Rie Tsutsumi
- Department of Nutrition and Metabolism, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Hiroshi Sakaue
- Department of Nutrition and Metabolism, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Yutaka Taketani
- Department of Clinical Nutrition and Food Management, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Koichi Sairyo
- Department of Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Akihiko Kawaura
- Kenshokai Gakuen College for Health and Welfare, Tokushima, Japan
| | - Eiji Takeda
- Kenshokai Gakuen College for Health and Welfare, Tokushima, Japan
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10
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Lu X, Chen Z, Watsky MA. Effects of 1,25 and 24,25 Vitamin D on Corneal Fibroblast VDR and Vitamin D Metabolizing and Catabolizing Enzymes. Curr Eye Res 2021; 46:1271-1282. [PMID: 33535006 DOI: 10.1080/02713683.2021.1884726] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Purpose: To investigate the effects of 1,25-Vit D3 and 24,25-Vit D3 on corneal fibroblast expression of the vitamin D-associated enzymes CYP27B1 and CYP24A1 and the roles of the vitamin D receptor (VDR) and protein disulfide isomerase, family A, member 3 (Pdia3) in these cells.Methods: CYP24A1, CYP27B1, VDR, and Pdia3 expression in corneas was detected using immunohistochemistry. Western blotting was used to measure protein expression in human and mouse fibroblasts, including VDR KO mouse cells, treated with 1,25-Vit D3 (20 nM) and 24,25-Vit D3 (100 nM). The Pdia3 inhibitor LOC14 was used to explore the role of Pdia3 as a Vit D3 receptor in these cells.Results: CYP24A1, CYP27B1, VDR, and Pdia3 were all expressed in mouse and human corneal fibroblasts. 1,25-Vit D3 significantly increased VDR expression in human and mouse fibroblasts. 1,25-Vit D3 and 24,25-VitD3 significantly increased CYP24A1 and CYP27B1 expression level in human, VDR WT mouse, and VDR KO mouse corneal fibroblasts. CYP24A1 and CYP27B1 expression was unchanged in VDR KO mouse fibroblasts treated with 1,25-Vit D3 or 24,25-Vit D3 plus LOC14. Human fibroblast VDR, CYP24A1, and CYP27B1 expression were unaffected by LOC14.Conclusions: Vitamin D metabolic enzymes, VDR, and Pdia3 are all expressed in mouse and human corneal fibroblasts. 1,25-Vit D3 modulates fibroblast vitamin D enzymes through both the VDR and Pdia3 pathways in a species-dependent manner. 24,25-Vit D3 can increase expression of fibroblast CYP24A1 and CYP27B1 in the absence of VDR and is likely involved in fibroblast regulation independent of 1,25-Vit D3 or VDR.
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Affiliation(s)
- Xiaowen Lu
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Zhong Chen
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Mitchell A Watsky
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
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Bikle DD. Vitamin D: Newer Concepts of Its Metabolism and Function at the Basic and Clinical Level. J Endocr Soc 2020; 4:bvz038. [PMID: 32051922 PMCID: PMC7007804 DOI: 10.1210/jendso/bvz038] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/06/2020] [Indexed: 02/08/2023] Open
Abstract
The interest in vitamin D continues unabated with thousands of publications contributing to a vast and growing literature each year. It is widely recognized that the vitamin D receptor (VDR) and the enzymes that metabolize vitamin D are found in many cells, not just those involved with calcium and phosphate homeostasis. In this mini review I have focused primarily on recent studies that provide new insights into vitamin D metabolism, mechanisms of action, and clinical applications. In particular, I examine how mutations in vitamin D metabolizing enzymes-and new information on their regulation-links vitamin D metabolism into areas such as metabolism and diseases outside that of the musculoskeletal system. New information regarding the mechanisms governing the function of the VDR elucidates how this molecule can be so multifunctional in a cell-specific fashion. Clinically, the difficulty in determining vitamin D sufficiency for all groups is addressed, including a discussion of whether the standard measure of vitamin D sufficiency, total 25OHD (25 hydroxyvitamin) levels, may not be the best measure-at least by itself. Finally, several recent large clinical trials exploring the role of vitamin D supplementation in nonskeletal diseases are briefly reviewed, with an eye toward what questions they answered and what new questions they raised.
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Affiliation(s)
- Daniel D Bikle
- Department of Medicine and Endocrine Research Unit, Veterans Affairs Medical Center and University of California, San Francisco, California
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12
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Genetic, environmental and biomarker considerations delineating the regulatory effects of vitamin D on central nervous system function. Br J Nutr 2020; 123:41-58. [PMID: 31640823 DOI: 10.1017/s000711451900268x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Studies show that vitamin D (vit-D) (25(OH)D), the bioactive metabolite (1,25(OH)2D3) and vit-D receptors (vit-D receptor; protein disulphide isomerase, family A member 3) are expressed throughout the brain, particularly in regions pivotal to learning and memory. This has led to the paradigm that avoiding vit-D deficiency is important to preserve cognitive function. However, presently, it is not clear if the common clinical measure of serum 25(OH)D serves as a robust surrogate marker for central nervous system (CNS) homeostasis or function. Indeed, recent studies report CNS biosynthesis of endogenous 25(OH)D, the CNS expression of the CYP group of enzymes which catalyse conversion to 1,25(OH)2D3 and thereafter, deactivation. Moreover, in the periphery, there is significant ethnic/genetic heterogeneity in vit-D conversion to 1,25(OH)2D3 and there is a paucity of studies which have actually investigated vit-D kinetics across the cerebrovasculature. Compared with peripheral organs, the CNS also has differential expression of receptors that trigger cellular response to 1,25(OH)2D3 metabolites. To holistically consider the putative association of peripheral (blood) abundance of 25(OH)D on cognitive function, herein, we have reviewed population and genetic studies, pre-clinical and clinical intervention studies and moreover have considered potential confounders of vit-D analysis.
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13
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Fleet JC. The role of vitamin D in the endocrinology controlling calcium homeostasis. Mol Cell Endocrinol 2017; 453:36-45. [PMID: 28400273 PMCID: PMC5529228 DOI: 10.1016/j.mce.2017.04.008] [Citation(s) in RCA: 153] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 04/07/2017] [Accepted: 04/08/2017] [Indexed: 12/14/2022]
Abstract
Vitamin D and its' metabolites are a crucial part of the endocrine system that controls whole body calcium homeostasis. The goal of this hormonal control is to regulate serum calcium levels so that they are maintained within a very narrow range. To achieve this goal, regulatory events occur in coordination at multiple tissues, e.g. the intestine, kidney, bone, and parathyroid gland. Production of the vitamin D endocrine hormone, 1,25 dihydroxyvitamin D (1,25(OH)2 D) is regulated by habitual dietary calcium intake and physiologic states like growth, aging, and the menopause. The molecular actions of 1,25(OH)2 D on calcium regulating target tissues are mediated predominantly by transcription controlled by the vitamin D receptor. A primary role for 1,25(OH)2 D during growth is to increase intestinal calcium absorption so that sufficient calcium is available for bone mineralization. However, vitamin D also has specific actions on kidney and bone.
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Affiliation(s)
- James C Fleet
- Department of Nutrition Science, Room G1B Stone Hall, Purdue University, West Lafayette, IN 47907-2059, United States.
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14
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de Jongh RT, van Schoor NM, Lips P. Changes in vitamin D endocrinology during aging in adults. Mol Cell Endocrinol 2017; 453:144-150. [PMID: 28602863 DOI: 10.1016/j.mce.2017.06.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 06/04/2017] [Accepted: 06/05/2017] [Indexed: 12/11/2022]
Abstract
Worldwide, vitamin D deficiency is a common finding. Within individuals 25-hydroxyvitamin D (25OH)D) concentrations remain fairly stable over time although large differences in individual longitudinal changes exist. During aging vitamin D metabolism and activity changes in several different ways. Intestinal resistance to 1,25(OH)2D develops which hampers intestinal calcium uptake. Vitamin D receptor number decreases with aging in several organs involved in calcium metabolism and 1alpha-hydroxylase activity decreases mainly due to a decrease in renal function reducing vitamin D activation. Effects of 1,25(OH)2D on cell proliferation and differentiation may influence potential anti-cancer effects whereas regulation of telomere length may result in longevity. In older individuals, vitamin D supplementation has positive effects on fracture risk, number of falls and physical function. Supplementation in older populations warrants specific attention. Effects on "non-classical" outcomes may be revealed by ongoing large randomized clinical trials with high doses of vitamin D.
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Affiliation(s)
- Renate T de Jongh
- Department of Internal Medicine and Endocrinology, VU University Medical Center, P.O. Box 7057, 1007 MB, Amsterdam, The Netherlands.
| | - Natasja M van Schoor
- Amsterdam Public Health Research Institute, Department of Epidemiology and Biostatistics, VU University Medical Center, P.O. Box 7057, 1007 MB, Amsterdam, The Netherlands.
| | - Paul Lips
- Department of Internal Medicine and Endocrinology, VU University Medical Center, P.O. Box 7057, 1007 MB, Amsterdam, The Netherlands; Amsterdam Public Health Research Institute, Department of Epidemiology and Biostatistics, VU University Medical Center, P.O. Box 7057, 1007 MB, Amsterdam, The Netherlands.
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15
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Li J, Yuan J, Miao Z, Guo Y. Effects of age on intestinal phosphate transport and biochemical values of broiler chickens. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2017; 30:221-228. [PMID: 27703131 PMCID: PMC5205610 DOI: 10.5713/ajas.16.0540] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 09/05/2016] [Accepted: 09/21/2016] [Indexed: 01/12/2023]
Abstract
OBJECTIVE The objective of this experiment was to characterize the mRNA expression profile of type IIb sodium-inorganic phosphate cotransporter (NaPi-IIb) and the biochemical values of serum alkaline phosphatase (AKP), calcium, inorganic phosphorus, tibial ash and minerals of broiler chickens with aging. METHODS A total of 56 one-day-old Arbor Acres male broiler chickens were used. Broiler chickens were weighed and samples were collected weekly from day 1. RESULTS The result showed that before the growth inflection point, ash, calcium, and phosphorus content in the tibia of broiler chickens increased with growth (before 3 weeks of age), although there were no significant differences in chicks at different ages in the later period of the experiment and weight gain rate was relatively slow at this stage (4 to 6 weeks). NaPi-IIb gene expression in the small intestine in the early growth stage was higher than that in the later growth stage. Expression of calbindin and the vitamin D receptor protein in the intestinal mucosa increased with age in the duodenum and jejunum. Serum AKP activity first increased and subsequently decreased after peaking at 1 week of age, but there was no significant difference after 3 weeks of age. CONCLUSION These results show that compared with the early growth stage, the weight-gain rate of broiler chickens in the late growth stage gradually decreased with gradual tibia maturation, along with weaker positive transport of phosphorus in the intestine and reinforced re-absorption of phosphorus in the kidney, which might be the reason that phosphorus requirement in the late growth stage was decreased.
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Affiliation(s)
- Jianhui Li
- College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Shanxi 030801,
China
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193,
China
| | - Jianmin Yuan
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193,
China
| | - Zhiqiang Miao
- College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Shanxi 030801,
China
| | - Yuming Guo
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193,
China
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Christakos S, Veldurthy V, Patel N, Wei R. Intestinal Regulation of Calcium: Vitamin D and Bone Physiology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1033:3-12. [PMID: 29101648 DOI: 10.1007/978-3-319-66653-2_1] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The principal function of vitamin D in the maintenance of calcium homeostasis is to increase intestinal calcium absorption. This conclusion was made from studies in vitamin D receptor (VDR) null mice which showed that rickets and osteomalacia were prevented when VDR null mice were fed a rescue diet that included high calcium, indicating that the skeletal abnormalities of the VDR null mice are primarily the result of impaired intestinal calcium absorption. Although vitamin D is critical for controlling intestinal calcium absorption, the mechanisms involved have remained incomplete. This chapter reviews studies, including studies in genetically modified mice, that have provided new insight and have challenged the traditional model of VDR-mediated calcium absorption.
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Affiliation(s)
- Sylvia Christakos
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers the State University of New Jersey, New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103, USA.
| | - Vaishali Veldurthy
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers the State University of New Jersey, New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103, USA
| | - Nishant Patel
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers the State University of New Jersey, New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103, USA
| | - Ran Wei
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers the State University of New Jersey, New Jersey Medical School, 185 South Orange Ave, Newark, NJ, 07103, USA
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17
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Vitamin D, calcium homeostasis and aging. Bone Res 2016; 4:16041. [PMID: 27790378 PMCID: PMC5068478 DOI: 10.1038/boneres.2016.41] [Citation(s) in RCA: 198] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 08/31/2016] [Accepted: 09/04/2016] [Indexed: 12/15/2022] Open
Abstract
Osteoporosis is characterized by low bone mass and microarchitecture deterioration of bone tissue, leading to enhanced bone fragility and consequent increase in fracture risk. Evidence is accumulating for an important role of calcium deficiency as the process of aging is associated with disturbed calcium balance. Vitamin D is the principal factor that maintains calcium homeostasis. Increasing evidence indicates that the reason for disturbed calcium balance with age is inadequate vitamin D levels in the elderly. In this article, an overview of our current understanding of vitamin D, its metabolism, and mechanisms involved in vitamin D-mediated maintenance of calcium homeostasis is presented. In addition, mechanisms involved in age-related dysregulation of 1,25(OH)2D3 action, recommended daily doses of vitamin D and calcium, and the use of vitamin D analogs for the treatment of osteoporosis (which remains controversial) are reviewed. Elucidation of the molecular pathways of vitamin D action and modifications that occur with aging will be an active area of future research that has the potential to reveal new therapeutic strategies to maintain calcium balance.
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18
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Granjon D, Bonny O, Edwards A. A model of calcium homeostasis in the rat. Am J Physiol Renal Physiol 2016; 311:F1047-F1062. [PMID: 27358053 DOI: 10.1152/ajprenal.00230.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 06/27/2016] [Indexed: 12/14/2022] Open
Abstract
We developed a model of calcium homeostasis in the rat to better understand the impact of dysfunctions such as primary hyperparathyroidism and vitamin D deficiency on calcium balance. The model accounts for the regulation of calcium intestinal uptake, bone resorption, and renal reabsorption by parathyroid hormone (PTH), vitamin D3, and Ca2+ itself. It is the first such model to incorporate recent findings regarding the role of the calcium-sensing receptor (CaSR) in the kidney, the presence of a rapidly exchangeable pool in bone, and the delayed response of vitamin D3 synthesis. Accounting for two (fast and slow) calcium storage compartments in bone allows the model to properly predict the effects of bisphophonates on the plasma levels of Ca2+ ([Ca2+]p), PTH, and vitamin D3 Our model also suggests that Ca2+ exchange rates between plasma and the fast pool vary with both sex and age, allowing [Ca2+]p to remain constant in spite of sex- and age-based hormonal and other differences. Our results suggest that the inconstant hypercalciuria that is observed in primary hyperparathyroidism can be attributed in part to counterbalancing effects of PTH and CaSR in the kidney. Our model also correctly predicts that calcimimetic agents such as cinacalcet bring down [Ca2+]p to within its normal range in primary hyperparathyroidism. In addition, the model provides a simulation of CYP24A1 inactivation that leads to a situation reminiscent of infantile hypercalcemia. In summary, our model of calcium handling can be used to decipher the complex regulation of calcium homeostasis.
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Affiliation(s)
- David Granjon
- Sorbonne Universités, UPMC Univ Paris 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France; and.,Department of Pharmacology and Toxicology, University of Lausanne, and Service of Nephrology, Lausanne University Hospital, Lausanne, Switzerland
| | - Olivier Bonny
- Department of Pharmacology and Toxicology, University of Lausanne, and Service of Nephrology, Lausanne University Hospital, Lausanne, Switzerland
| | - Aurélie Edwards
- Sorbonne Universités, UPMC Univ Paris 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France; and
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Christakos S, Dhawan P, Verstuyf A, Verlinden L, Carmeliet G. Vitamin D: Metabolism, Molecular Mechanism of Action, and Pleiotropic Effects. Physiol Rev 2016; 96:365-408. [PMID: 26681795 PMCID: PMC4839493 DOI: 10.1152/physrev.00014.2015] [Citation(s) in RCA: 1075] [Impact Index Per Article: 134.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
1,25-Dihydroxvitamin D3 [1,25(OH)2D3] is the hormonally active form of vitamin D. The genomic mechanism of 1,25(OH)2D3 action involves the direct binding of the 1,25(OH)2D3 activated vitamin D receptor/retinoic X receptor (VDR/RXR) heterodimeric complex to specific DNA sequences. Numerous VDR co-regulatory proteins have been identified, and genome-wide studies have shown that the actions of 1,25(OH)2D3 involve regulation of gene activity at a range of locations many kilobases from the transcription start site. The structure of the liganded VDR/RXR complex was recently characterized using cryoelectron microscopy, X-ray scattering, and hydrogen deuterium exchange. These recent technological advances will result in a more complete understanding of VDR coactivator interactions, thus facilitating cell and gene specific clinical applications. Although the identification of mechanisms mediating VDR-regulated transcription has been one focus of recent research in the field, other topics of fundamental importance include the identification and functional significance of proteins involved in the metabolism of vitamin D. CYP2R1 has been identified as the most important 25-hydroxylase, and a critical role for CYP24A1 in humans was noted in studies showing that inactivating mutations in CYP24A1 are a probable cause of idiopathic infantile hypercalcemia. In addition, studies using knockout and transgenic mice have provided new insight on the physiological role of vitamin D in classical target tissues as well as evidence of extraskeletal effects of 1,25(OH)2D3 including inhibition of cancer progression, effects on the cardiovascular system, and immunomodulatory effects in certain autoimmune diseases. Some of the mechanistic findings in mouse models have also been observed in humans. The identification of similar pathways in humans could lead to the development of new therapies to prevent and treat disease.
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Affiliation(s)
- Sylvia Christakos
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, New Jersey; and Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Puneet Dhawan
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, New Jersey; and Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Annemieke Verstuyf
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, New Jersey; and Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Lieve Verlinden
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, New Jersey; and Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Geert Carmeliet
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, The State University of New Jersey, New Jersey Medical School, Newark, New Jersey; and Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
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Abstract
For humans and rodents, duodenum is a very important site of calcium absorption since it is exposed to ionized calcium released from dietary complexes by gastric acid. Calcium traverses the duodenal epithelium via both transcellular and paracellular pathways in a vitamin D-dependent manner. After binding to the nuclear vitamin D receptor, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] upregulates the expression of several calcium transporter genes, e.g., TRPV5/6, calbindin-D9k, plasma membrane Ca(2+)-ATPase1b, and NCX1, thereby enhancing the transcellular calcium transport. This action has been reported to be under the regulation of parathyroid-kidney-intestinal and bone-kidney-intestinal axes, in which the plasma calcium and fibroblast growth factor-23 act as negative feedback regulators, respectively. 1,25(OH)2D3 also modulates the expression of tight junction-related genes and convective water flow, presumably to increase the paracellular calcium permeability and solvent drag-induced calcium transport. However, vitamin D-independent calcium absorption does exist and plays an important role in calcium homeostasis under certain conditions, particularly in neonatal period, pregnancy, and lactation as well as in naturally vitamin D-impoverished subterranean mammals.
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Effects of high phosphorus diet on bone metabolism-related gene expression in young and aged mice. J Nutr Metab 2014; 2014:575932. [PMID: 25505982 PMCID: PMC4253706 DOI: 10.1155/2014/575932] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 11/09/2014] [Indexed: 01/01/2023] Open
Abstract
In this study, the effects of high phosphorus (P) diet on bone metabolism-related gene expression were investigated in young and aged mice. Twelve- and 80-week-old ddY male mice were divided into two groups, respectively, and fed a control diet containing 0.3% P or a high P diet containing 1.2% P. After 4 weeks of treatment, serum parathyroid hormone (PTH) concentration was significantly higher in the high P groups than in the control groups in both young and aged mice and was significantly higher in aged mice than in young mice fed the high P diet. High P diet significantly increased receptor activator of NF-κB ligand (RANKL) mRNA in the femur of both young and aged mice and significantly increased the RANKL/osteoprotegerin (OPG) mRNA ratio only in aged mice. High P diet significantly increased mRNA expression of transient receptor potential vanilloid type 6, calbindin-D9k, and plasma membrane Ca(2+)-ATPase 1b in the duodenum of both young and aged mice. These results suggest that high P diet increased RANKL mRNA expression in the femur and calcium absorption-related gene expression in the duodenum regardless of age. Furthermore, the high P diet-induced increase in PTH secretion might increase the RANKL/OPG mRNA ratio in aged mice.
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Abstract
The majority of clinical complaints derive from disorders of calcium metabolism and are associated with a wide variety of clinical symptoms caused by numerous diseases with entirely different types of pathophysiology. The prognosis varies from favorable to fatal depending on the pathophysiology of the underlying disorder of calcium metabolism; therefore, the diagnostic work-up aims to quickly identify the underlying disease causing the disturbance in calcium homeostasis. Every clinical situation with a diminished state of calcium absorption is treated with calcium and vitamin D in varying doses whereas every disorder with an increased calcium absorptive or resorptive state is treated with improved diuresis in addition to antiresorptive drugs, such as bisphosphonates. In many situations the management of a disturbed calcium balance requires an interdisciplinary approach in order to treat the underlying disease in parallel with correction of the calcium homeostasis.
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23
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Douard V, Patel C, Lee J, Tharabenjasin P, Williams E, Fritton JC, Sabbagh Y, Ferraris RP. Chronic high fructose intake reduces serum 1,25 (OH)2D3 levels in calcium-sufficient rodents. PLoS One 2014; 9:e93611. [PMID: 24718641 PMCID: PMC3981704 DOI: 10.1371/journal.pone.0093611] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 03/05/2014] [Indexed: 12/14/2022] Open
Abstract
Excessive fructose consumption inhibits adaptive increases in intestinal Ca2+ transport in lactating and weanling rats with increased Ca2+ requirements by preventing the increase in serum levels of 1,25(OH)2D3. Here we tested the hypothesis that chronic fructose intake decreases 1,25(OH)2D3 levels independent of increases in Ca2+ requirements. Adult mice fed for five wk a high glucose-low Ca2+ diet displayed expected compensatory increases in intestinal and renal Ca2+ transporter expression and activity, in renal CYP27B1 (coding for 1α-hydroxylase) expression as well as in serum 1,25(OH)2D3 levels, compared with mice fed isocaloric glucose- or fructose-normal Ca2+ diets. Replacing glucose with fructose prevented these increases in Ca2+ transporter, CYP27B1, and 1,25(OH)2D3 levels induced by a low Ca2+ diet. In adult mice fed for three mo a normal Ca2+ diet, renal expression of CYP27B1 and of CYP24A1 (24-hydroxylase) decreased and increased, respectively, when the carbohydrate source was fructose instead of glucose or starch. Intestinal and renal Ca2+ transporter activity and expression did not vary with dietary carbohydrate. To determine the time course of fructose effects, a high fructose or glucose diet with normal Ca2+ levels was fed to adult rats for three mo. Serum levels of 1,25(OH)2D3 decreased and of FGF23 increased significantly over time. Renal expression of CYP27B1 and serum levels of 1,25(OH)2D3 still decreased in fructose- compared to those in glucose-fed rats after three mo. Serum parathyroid hormone, Ca2+ and phosphate levels were normal and independent of dietary sugar as well as time of feeding. Thus, chronically high fructose intakes can decrease serum levels of 1,25(OH)2D3 in adult rodents experiencing no Ca2+ stress and fed sufficient levels of dietary Ca2+. This finding is highly significant because fructose constitutes a substantial portion of the average diet of Americans already deficient in vitamin D.
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Affiliation(s)
- Veronique Douard
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers Biomedical and Health Sciences (RBHS), Newark, New Jersey, United States of America
- * E-mail:
| | - Chirag Patel
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers Biomedical and Health Sciences (RBHS), Newark, New Jersey, United States of America
| | - Jacklyn Lee
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers Biomedical and Health Sciences (RBHS), Newark, New Jersey, United States of America
| | - Phuntila Tharabenjasin
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers Biomedical and Health Sciences (RBHS), Newark, New Jersey, United States of America
| | - Edek Williams
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey, United States of America
| | - J. Christopher Fritton
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey, United States of America
- Department of Orthopaedics, New Jersey Medical School, RBHS, Newark, New Jersey, United States of America
| | - Yves Sabbagh
- Tissue Protection and Repair, Sanofi-Genzyme R&D Center, Genzyme, a Sanofi Company, Framingham, Massachusetts, United States of America
| | - Ronaldo P. Ferraris
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers Biomedical and Health Sciences (RBHS), Newark, New Jersey, United States of America
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Gallagher JC, Jindal PS, Smith LM. Vitamin D does not increase calcium absorption in young women: a randomized clinical trial. J Bone Miner Res 2014; 29:1081-7. [PMID: 24166866 DOI: 10.1002/jbmr.2121] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 09/27/2013] [Accepted: 10/14/2013] [Indexed: 11/11/2022]
Abstract
It is commonly said that vitamin D should be used to increase calcium absorption. We tested this statement in a dose-response study of vitamin D on calcium absorption. A total of 198 white and African American women, aged 25 to 45 years, with vitamin D insufficiency, serum 25-hydroxyvitamin D (25OHD) <20 ng/mL, were randomized in a double-blind study to vitamin D3 400, 800, 1600, 2400 IU, or placebo. A calcium supplement was given to increase mean calcium intake at baseline from 706 mg/d to 1031 mg/d. Calcium absorption was measured at baseline and after 12 months using a single isotope method with radiocalcium45 and 100 mg of calcium. Mean baseline serum 25OHD was 13.4 ng/mL (33.5 nmol/L) and increased to 40 ng/mL (100 nmol/L) on the highest dose of 2400 IU. Using a multivariate regression analysis with significant predictors, baseline absorption, calcium intake, and weight, there was no increase in 12-month calcium absorption compared with baseline on any dose of vitamin D in either whites or African Americans. There was no significant relationship between 12-month calcium absorption and final serum 25OHD. In an analysis of calcium absorption and serum 25OHD at baseline, serum 25OHD levels were divided into groups: 0 to 5, 6 to 10, 11 to 15, or 16 to 20 ng/mL. There was no evidence of a threshold decrease in calcium absorption or serum 1,25 dihydroxyvitamin D (1,25(OH)2 D) amongst the lowest groups. Vitamin D doses up to 2400 IU daily did not increase calcium absorption. No threshold level of serum 25OHD for calcium absorption was found at baseline or in the longitudinal study, suggesting that active transport of calcium is saturated at very low serum 25OHD levels <5 ng/mL. There is no need to recommend vitamin D for increasing calcium absorption in normal subjects. Very efficient calcium absorption at very low levels of serum 25OHD explains why people do not develop osteomalacia provided that dietary intakes of calcium and phosphorus are adequate.
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Fedeli D, Carloni M, Nasuti C, Gambini A, Scocco V, Gabbianelli R. Early life permethrin exposure leads to hypervitaminosis D, nitric oxide and catecholamines impairment. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2013; 107:93-7. [PMID: 25149241 DOI: 10.1016/j.pestbp.2013.05.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 04/12/2013] [Accepted: 05/13/2013] [Indexed: 05/25/2023]
Abstract
The aim of this study is to gain more knowledge on the impact of early life pesticide exposure on premature aging. The effect of a low dose of the insecticide permethrin administered to rats during early life (1/50 LD50, from 6th to 21st day of life) was analyzed by measuring some metabolites in plasma and urine of 500-day-old animals. Significant differences in early life treated rats compared to the control group were found in the plasma levels of Ca(++), Na(+), 25-hydroxy-vitamin D, adrenaline, noradrenaline, nitric oxide, cholesterol and urea while in urine only Na(+) content was different. These results add information on the impact of permethrin during the neonatal period, supporting the evidence that early life environmental exposure to xenobiotics has long-term effects, inducing modifications in adulthood that can be revealed by the analysis of some macroelements, metabolites and catecholamines in plasma, when rats are 500 days old.
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Affiliation(s)
| | | | | | - Anna Gambini
- Azienda Ospedaliera Universitaria, Ospedali Riuniti Umberto I, Lancisi, Salesi, Ancona, Italy
| | - Vitangelo Scocco
- Azienda Ospedaliera Universitaria, Ospedali Riuniti Umberto I, Lancisi, Salesi, Ancona, Italy
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Gonzalez Pardo V, Russo de Boland A. Age-related changes in the response of intestinal cells to 1α,25(OH)2-vitamin D3. Ageing Res Rev 2013; 12:76-89. [PMID: 22706185 DOI: 10.1016/j.arr.2012.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 06/01/2012] [Accepted: 06/06/2012] [Indexed: 12/14/2022]
Abstract
The hormonally active form of vitamin D(3), 1α,25(OH)(2)-vitamin D(3), acts in intestine, its major target tissue, where its actions are of regulatory and developmental importance: regulation of intracellular calcium through modulation of second messengers and activation of mitogenic cascades leading to cell proliferation. Several causes have been postulated to modify the hormone response in intestinal cells with ageing, among them, alterations of vitamin D receptor (VDR) levels and binding sites, reduced expression of G-proteins and hormone signal transduction changes. The current review summarizes the actual knowledge regarding the molecular and biochemical basis of age-impaired 1α,25(OH)(2)-vitamin D(3) receptor-mediated signaling in intestinal cells. A fundamental understanding why the hormone functions are impaired with age will enhance our knowledge of its importance in intestinal cell physiology.
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Affiliation(s)
- Verónica Gonzalez Pardo
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Argentina
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Shapses SA, Sukumar D, Schneider SH, Schlussel Y, Brolin RE, Taich L. Hormonal and dietary influences on true fractional calcium absorption in women: role of obesity. Osteoporos Int 2012; 23:2607-14. [PMID: 22282301 PMCID: PMC4016952 DOI: 10.1007/s00198-012-1901-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 11/18/2011] [Indexed: 10/14/2022]
Abstract
UNLABELLED The goal in this study was to examine the hormonal and dietary predictors of true fractional Ca absorption (TFCA) in adult women and to determine whether TFCA differs due to body weight. Results showed that TFCA is higher in obese individuals and dietary fat, estradiol, and 1,25-dihydroxy vitamin D are the most significant positive predictors of TFCA in adult women. INTRODUCTION Calcium absorption is an important determinant of calcium balance and is influenced by several factors. Previous studies have identified that age, intake of protein, fat and fiber, and hormones such as 1, 25-dihyroxyvitamin D (1,25(OH)(2)D(3)) influence absorption. The determinants of TFCA using the double isotope method, the gold standard estimate of absorption, have not been examined previously in adult women nor has the role of obesity been addressed. METHODS In this study, we examined the hormonal and dietary predictors of TFCA in adult women with a wide range of age, body weights, and nutrient intake. TFCA was measured using dual stable isotope ((42)Ca and (43)Ca) technique. Serum was analyzed for bone-regulating hormones, and dietary information was obtained through food records. The independent dietary factors and hormonal predictors (25-hydroxyvitamin D, 1,25(OH)(2)D(3), parathyroid hormone, and estradiol) of TFCA were analyzed using multiple regression analysis. RESULTS Two hundred twenty-nine women aged 54 ± 11 years old (24-75 years) and with BMI of 31 ± 7.0 kg/m(2) were eligible and were categorized into tertiles of body mass index (BMI) into leaner, overweight, and obese. In the entire group of women, total fat intake, estradiol, and 1,25(OH)(2)D(3) are significant positive predictors (p < 0.05). As expected, age is a significant negative predictor of TFCA (R (2) = 26%). TFCA is higher in obese women compared to non-obese women (p < 0.05). CONCLUSION Together, these data show that dietary fat is the most significant positive predictor of TFCA which may have implications for dietary intake for non-obese individuals who are more likely to have lower and potentially compromised Ca absorption.
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Affiliation(s)
- S A Shapses
- Department of Nutritional Sciences, Rutgers University, 96 Lipman Drive, New Brunswick, NJ 08901-8525, USA.
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1,25-Dihydroxyvitamin D fluctuations in cardiac surgery are related to age and clinical outcome*. Crit Care Med 2012; 40:2073-81. [PMID: 22584760 DOI: 10.1097/ccm.0b013e31824e8c42] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
OBJECTIVE To investigate the interrelationship between cardiac surgery, age, circulating concentrations of the vitamin D hormone 1,25-dihydroxyvitamin D, and clinical outcome. DESIGN Prospective, monocentric, two-arm parallel study. SETTING Tertiary Heart and Diabetes Center in the Federal State of North Rhine-Westphalia, Germany. PATIENTS Twenty-nine cardiac surgical patients aged ≤ 65 yrs and 30 patients ≥ 75 yrs. MEASUREMENTS We assessed 1,25-dihydroxyvitamin D and other biochemical parameters of mineral metabolism (calcium, phosphate, 25-hydroxyvitamin D, and parathyroid hormone), various inflammatory markers (C-reactive protein, interleukin-6 and 8), and different immunological parameters (CD4 and CD8 cells, monocyte HLA-DR expression). We collected blood samples preoperatively, immediately after surgery, and on postoperative days 1, 5, and 30. In addition, we assessed adverse outcome until discharge as a composite of myocardial infarction, low cardiac output syndrome, infection, stroke, or in-hospital death. RESULTS There were significant transient cardiac surgery-related fluctuations in 1,25-dihydroxyvitamin D and the aforementioned parameters of mineral metabolism, inflammation, and immune status. Compared to younger patients, older patients had consistently lower 1,25-dihydroxyvitamin D and phosphate levels (p = .013 and p = .036, respectively) and significantly higher interleukin 6 and 8 levels (p = .008 and p < .001, respectively). Circulating 1,25-dihydroxyvitamin D was directly related to glomerular filtration rate (R(2) = .227; p < .001) and inversely related to interleukin 6 (R(2) = .105; p = .012). The rate of adverse outcome tended to be higher in older than in younger patients (20.0% vs. 3.5%; p = .081). In risk score-adjusted logistic regression analysis, adverse outcome risk decreased by 7.7% (SE: 3.7%) for each pmol/L increment in 1,25-dihydroxyvitamin D (p = .037). CONCLUSIONS Circulating 1,25-dihydroxyvitamin D levels fluctuate in relation to cardiac surgery. Low 1,25-dihydroxyvitamin D levels are associated with inflammatory processes and age-related differences in clinical outcome. Future studies should determine whether therapies aimed at treating low 1,25-dihydroxyvitamin D levels can improve the outcome in older cardiac surgery patients.
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Christakos S. Recent advances in our understanding of 1,25-dihydroxyvitamin D(3) regulation of intestinal calcium absorption. Arch Biochem Biophys 2012; 523:73-6. [PMID: 22230327 DOI: 10.1016/j.abb.2011.12.020] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 12/23/2011] [Accepted: 12/26/2011] [Indexed: 02/07/2023]
Abstract
Calcium is required for many cellular processes including muscle contraction, nerve pulse transmission, stimulus secretion coupling and bone formation. The principal source of new calcium to meet these essential functions is from the diet. Intestinal absorption of calcium occurs by an active transcellular path and by a non-saturable paracellular path. The major factor influencing intestinal calcium absorption is vitamin D and more specifically the hormonally active form of vitamin D, 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)). This article emphasizes studies that have provided new insight related to the mechanisms involved in the intestinal actions of 1,25(OH)(2)D(3). The following are discussed: recent studies, including those using knock out mice, that suggest that 1,25(OH)(2)D(3) mediated calcium absorption is more complex than the traditional transcellular model; evidence for 1,25(OH)(2)D(3) mediated active transport of calcium by distal as well as proximal segments of the intestine; 1,25(OH)(2)D(3) regulation of paracellular calcium transport and the role of 1,25(OH)(2)D(3) in protection against mucosal injury.
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Affiliation(s)
- Sylvia Christakos
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, NJ 07103, USA.
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Christakos S, Dhawan P, Porta A, Mady LJ, Seth T. Vitamin D and intestinal calcium absorption. Mol Cell Endocrinol 2011; 347:25-9. [PMID: 21664413 PMCID: PMC3405161 DOI: 10.1016/j.mce.2011.05.038] [Citation(s) in RCA: 193] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 05/23/2011] [Accepted: 05/25/2011] [Indexed: 12/14/2022]
Abstract
The principal function of vitamin D in calcium homeostasis is to increase calcium absorption from the intestine. Calcium is absorbed by both an active transcellular pathway, which is energy dependent, and by a passive paracellular pathway through tight junctions. 1,25Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) the hormonally active form of vitamin D, through its genomic actions, is the major stimulator of active intestinal calcium absorption which involves calcium influx, translocation of calcium through the interior of the enterocyte and basolateral extrusion of calcium by the intestinal plasma membrane pump. This article reviews recent studies that have challenged the traditional model of vitamin D mediated transcellular calcium absorption and the crucial role of specific calcium transport proteins in intestinal calcium absorption. There is also increasing evidence that 1,25(OH)(2)D(3) can enhance paracellular calcium diffusion. The influence of estrogen, prolactin, glucocorticoids and aging on intestinal calcium absorption and the role of the distal intestine in vitamin D mediated intestinal calcium absorption are also discussed.
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Affiliation(s)
- Sylvia Christakos
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School and Graduate School of Biomedical Sciences, Newark, NJ 07103, USA.
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Nordin BEC. Evolution of the calcium paradigm: the relation between vitamin D, serum calcium and calcium absorption. Nutrients 2010; 2:997-1004. [PMID: 22254068 PMCID: PMC3257716 DOI: 10.3390/nu2090997] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 08/18/2010] [Accepted: 08/24/2010] [Indexed: 11/16/2022] Open
Abstract
Osteoporosis is the index disease for calcium deficiency, just as rickets/osteomalacia is the index disease for vitamin D deficiency, but there is considerable overlap between them. The common explanation for this overlap is that hypovitaminosis D causes malabsorption of calcium which then causes secondary hyperparathyroidism and is effectively the same thing as calcium deficiency. This paradigm is incorrect. Hypovitaminosis D causes secondary hyperparathyroidism at serum calcidiol levels lower than 60 nmol/L long before it causes malabsorption of calcium because serum calcitriol (which controls calcium absorption) is maintained until serum calcidiol falls below 20 nmol/L. This secondary hyperparathyroidism, probably due to loss of a "calcaemic" action of vitamin D on bone first described in 1957, destroys bone and explains why vitamin D insufficiency is a risk factor for osteoporosis. Vitamin D thus plays a central role in the maintenance of the serum (ionised) calcium, which is more important to the organism than the preservation of the skeleton. Bone is sacrificed when absorbed dietary calcium does not match excretion through the skin, kidneys and bowel which is why calcium deficiency causes osteoporosis in experimental animals and, by implication, in humans.
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Wong MSK, Delansorne R, Man RYK, Svenningsen P, Vanhoutte PM. Chronic treatment with vitamin D lowers arterial blood pressure and reduces endothelium-dependent contractions in the aorta of the spontaneously hypertensive rat. Am J Physiol Heart Circ Physiol 2010; 299:H1226-34. [PMID: 20693391 DOI: 10.1152/ajpheart.00288.2010] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Vitamin D has cardiovascular protective effects besides regulating calcium homeostasis. To examine the chronic in vivo effect of a physiological dose of 1,25-dihydroxyvitamin D(3) on the occurrence of endothelium-dependent contractions, spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) were treated with the vitamin D derivative for 6 wk. The serum 1,25-dihydroxyvitamin D(3) level of both treated WKY and SHR was significantly higher than in untreated rats while the mean arterial blood pressure of the treated SHR was significantly lower than that of control SHR. Aortic rings with or without endothelium were studied in conventional organ chambers for isometric force measurement. Confocal microscopy was used to measure the cytosolic free calcium concentration (with the fluorescent dye fluo 4) and reactive oxygen species (ROS; with dichlorodihydrofluorescein diacetate). Reverse transcription PCR and Western blotting were used to determine the mRNA and protein expression level of cyclooxygenase-1 (COX-1), prostacyclin synthase, and thromboxane synthase. The endothelium-dependent concentration-contraction curves to both acetylcholine- and A-23187-induced contractions were shifted to the right in aortas from treated SHR but not from treated WKY. The chronic treatment normalized the relaxations of contracted preparations to acetylcholine. There were no significant differences in the increases in cytosolic free calcium concentration evoked by acetylcholine and A-23187 between control and treated groups. The endothelial ROS level was higher in SHR than WKY aortas and reduced by the chronic treatment. The gene and protein expression studies indicated that the overexpression of COX-1 observed in SHR aorta was reduced by the chronic treatment. These results demonstrate that chronic treatment with 1,25-dihydroxyvitamin D(3) modulates vascular tone and this modulation is accompanied by a lowered blood pressure, reduced expression of COX-1 mRNA and protein, and reduced ROS level in SHR. The reduction in endothelium-dependent contractions does not involve the surge in endothelial cytosolic calcium concentration that initiates the contractions.
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Affiliation(s)
- Michael S K Wong
- Department of Pharmacology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong
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Ikeda R, Mizoguchi K. Hachimijiogan (Ba-Wei-Di-Huang-Wan), a herbal medicine, improves unbalance of calcium metabolism in aged rats. JOURNAL OF ETHNOPHARMACOLOGY 2009; 124:176-181. [PMID: 19409475 DOI: 10.1016/j.jep.2009.04.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 04/20/2009] [Indexed: 05/27/2023]
Abstract
AIM OF THE STUDY Aged animals as well as elderly humans commonly exhibit calcium (Ca) shortage because of increased Ca excretion into urine and decreased intestinal Ca absorption, which induce elevation of serum PTH levels to maintain serum Ca levels between a normal physiological range. The most important organ that regulates this Ca homeostasis is the kidney. Hachimijiogan (HJG), a traditional herbal medicine in Japan and China, has been used for treating clinical diseases associated with kidney dysfunctions in elderly humans. However, the mechanisms of its pharmacological actions remain to be understood poorly. The present study was designed to examine whether HJG improves age-related unbalance of Ca metabolism at the systemic level using aged rats. MATERIALS AND METHODS HJG was administered to 21-month-old aged rats for 3 months, and several parameters associated with Ca metabolism in serum and urine were measured. RESULTS Although HJG as well as aging itself did not affect serum Ca levels compared to young (11-week-old) rats, HJG improved increase in urinary Ca excretion and elevation of serum parathyroid hormone (PTH) levels in aged rats. However, HJG did not improve marked reduction of intestinal Ca absorption in aged rats. CONCLUSION HJG showed regulating action for age-related unbalance of Ca metabolism at the systemic level. This finding would provide useful information for treating age-related several disorders associated with Ca unbalance.
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Affiliation(s)
- Ryuji Ikeda
- Section of Oriental Medicine, Department of Geriatric Medicine, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology (NCGG), 36-3 Gengo, Morioka-cho, Obu, Aichi 474-8522, Japan
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Nordin BEC, Morris HA, Horowitz M, Coates PS, O'Loughlin PD, Need AG. Calcium malabsorption does not cause secondary hyperparathyroidism. Calcif Tissue Int 2009; 85:31-6. [PMID: 19488668 DOI: 10.1007/s00223-009-9258-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Accepted: 05/04/2009] [Indexed: 02/07/2023]
Abstract
We challenge the widespread assumption that malabsorption of calcium per se causes secondary hyperparathyroidism. Serum parathyroid hormone (PTH) does not rise at the menopause despite the fall in calcium absorption, nor is it raised in osteoporotic women with vertebral fractures despite their low calcium absorption. The age-related rise in serum PTH can be accounted for by the age-related fall in serum 25(OH)D and/or decline in renal function with consequent loss of the calcemic action of vitamin D on bone. The reference interval for serum PTH is established in the fasting state when it is at the top of its diurnal cycle and is maintaining serum ionized calcium at the expense of bone to meet the calcium being lost through skin, bowel, and kidneys. There is no evidence that the fasting PTH is influenced by the previous day's intake or absorption of calcium, although it can be lowered by a large evening calcium supplement. Malabsorption of calcium-like dietary calcium deficiency-is a risk factor for osteoporosis because it reduces or prevents the normal food-related daytime fall in PTH and bone resorption, not because it causes secondary hyperparathyroidism.
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Xue Y, Fleet JC. Intestinal vitamin D receptor is required for normal calcium and bone metabolism in mice. Gastroenterology 2009; 136:1317-27, e1-2. [PMID: 19254681 PMCID: PMC2695717 DOI: 10.1053/j.gastro.2008.12.051] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 11/25/2008] [Accepted: 12/11/2008] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS Vitamin D receptor (VDR)-knockout mice develop severe hypocalcemia and rickets, accompanied by disruption of active intestinal calcium absorption. To specifically study the effects of VDR in intestinal calcium absorption, we investigated whether restoration of intestinal VDR is sufficient to recover the phenotype of VDR-knockout mice. METHODS We generated mice with intestine-specific transgenic expression of human VDR and crossed them to VDR knockout mice. The intestine, kidney, and bone phenotypes of the VDR- knockout mice with intestine-specific expression of human VDR (knockout/transgenic [KO/TG]) were analyzed. RESULTS Transgenic expression of VDR in the intestine of VDR-knockout mice normalized duodenal vitamin D-regulated calcium absorption as well as vitamin D-regulated calcium binding protein D9k and TRPV6 gene expression in the duodenum and proximal colon. As a result, animal growth and the serum levels of calcium and parathyroid hormone were normalized in KO/TG mice. Other phenotypes were revealed when calcium metabolism was normalized in KO/TG mice: serum 1,25 dihydroxyvitamin D levels were higher in KO/TG mice than normal mice owing to reduced renal expression of the vitamin D-degrading enzyme CYP24, urinary calcium excretion was higher and associated with lower renal calcium binding protein D9k and calcium binding protein D28k than normal mice, and bone density and volume increased in KO/TG compared with normal mice owing to increased mineral apposition rate and osteoblast number. CONCLUSIONS Intestinal VDR and vitamin D-regulated intestinal calcium absorption are critical for controlling whole-body calcium metabolism in growing mice. Normalizing intestinal calcium absorption and metabolism reveals essential roles for VDR in control of bone formation and renal control of serum 1,25(OH)2D and urinary calcium excretion.
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Affiliation(s)
- Yingben Xue
- Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47907-2059
| | - James C. Fleet
- Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47907-2059,Center for Gene-Environment Interactions, Purdue University, West Lafayette, IN 47907-2059,Corresponding author: James C. Fleet, Ph.D., Purdue University, 700 West State St., West Lafayette, IN 47906-2059, (O) 1-765-494-0302, (F) 1-765-494-0906, E-mail address:
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Murphy EF, Hooiveld GJ, Müller M, Calogero RA, Cashman KD. The effect of trans-10, cis-12 conjugated linoleic acid on gene expression profiles related to lipid metabolism in human intestinal-like Caco-2 cells. GENES AND NUTRITION 2009; 4:103-12. [PMID: 19283423 DOI: 10.1007/s12263-009-0116-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Accepted: 02/16/2009] [Indexed: 11/29/2022]
Abstract
We conducted an in-depth investigation of the effects of conjugated linoleic acid (CLA) on the expression of key metabolic genes and genes of known importance in intestinal lipid metabolism using the Caco-2 cell model. Cells were treated with 80 mumol/L of linoleic acid (control), trans-10, cis-12 CLA or cis-9, trans-11 CLA. RNA was isolated from the cells, labelled and hybridized to the Affymetrix U133 2.0 Plus arrays (n = 3). Data and functional analysis were preformed using Bioconductor. Gene ontology analysis (GO) revealed a significant enrichment (P < 0.0001) for the GO term lipid metabolism with genes up-regulated by trans-10, cis-12 CLA. Trans-10, cis-12 CLA, but not cis-9, trans-11 CLA, altered the expression of a number of genes involved in lipid transport, fatty acid metabolism, lipolysis, beta-oxidation, steroid metabolism, cholesterol biosynthesis, membrane lipid metabolism, gluconeogenesis and the citrate cycle. These observations warrant further investigation to understand their potential role in the metabolic syndrome.
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Affiliation(s)
- Eileen F Murphy
- Department of Food and Nutritional Sciences, University College Cork, Cork, Ireland,
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Heat shock protein 90beta: a novel mediator of vitamin D action. Biochem Biophys Res Commun 2008; 367:578-83. [PMID: 18182164 DOI: 10.1016/j.bbrc.2007.12.179] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Accepted: 12/30/2007] [Indexed: 12/30/2022]
Abstract
We investigated the role of Heat shock protein 90 (Hsp90) in vitamin D action in Caco-2 cells using geldanamycin (GA) to block Hsp90 function and RNA interference to reduce Hsp90beta expression. When cells were exposed to GA, vitamin D-mediated gene expression and transcriptional activity were inhibited by 69% and 54%, respectively. Gel shift analysis indicated that GA reduced vitamin D-mediated DNA binding activity of the vitamin D receptor (VDR). We tested the specific role of Hsp90beta by knocking down its expression with stably expressed short hairpin RNA. Vitamin D-induced gene expression and transcriptional activity were reduced by 90% and 80%, respectively, in Hsp90beta-deficient cells. Nuclear protein for VDR and RXRalpha, its heterodimer partner, were not reduced in Hsp90beta-deficient cells. These findings indicate that Hsp90beta is needed for optimal vitamin D responsiveness in the enterocyte and demonstrate a specific role for Hsp90beta in VDR signaling.
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Riner K, Boos A, Hässig M, Liesegang A. Vitamin D receptor distribution in intestines of domesticated sheepOvis ammon f. aries. J Morphol 2008; 269:144-52. [DOI: 10.1002/jmor.10574] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Boos A, Riner K, Hässig M, Liesegang A. Immunohistochemical Demonstration of Vitamin D Receptor Distribution in Goat Intestines. Cells Tissues Organs 2007; 186:121-8. [PMID: 17489022 DOI: 10.1159/000102540] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Indexed: 02/05/2023] Open
Abstract
Vitamin D (VD) plays an important role in calcium homeostasis. 1,25-Dihydroxycholecalciferol or calcitriol modulates gene transcription via nuclear VD receptors (VDR). In the intestines, VD promotes calcium resorption via VDR. VDR has not been systematically assessed within the intestine in any species. We therefore present a semiquantitative immunohistochemical study of the distribution patterns of VDR in goat intestines. Intestinal tissue probes were collected from 5 lambs and 5 non-lactating non-pregnant dams, fixed in formalin, embedded in paraffin and assessed for VDR. Nuclear VDR immunoreaction was scored semiquantitatively. VDR exhibited a segment-specific distribution pattern. Goblet cells were always devoid of VDR. Enterocytes within the surface epithelium and the superficial crypts generally demonstrated only a weak immunoreaction along the length of the intestine, while basally and/or intermediately located crypt epithelial cells exhibited strong VDR immunoreactions in the duodenum, jejunum and colon descendens. The difference in VDR staining between deep and superficial locations was most prominent in the duodenum and less evident in the jejunum, ileum and colon descendens. Results demonstrate that VDR distribution exhibits cell type-, segment- and location-specific patterns in the goat. Data may serve as a basis for future experiments on the role of VDR in Ca metabolism.
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Affiliation(s)
- Alois Boos
- Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zürich, Zürich, Switzerland.
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Song Y, Fleet JC. Intestinal resistance to 1,25 dihydroxyvitamin D in mice heterozygous for the vitamin D receptor knockout allele. Endocrinology 2007; 148:1396-402. [PMID: 17110426 PMCID: PMC2617756 DOI: 10.1210/en.2006-1109] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We tested the hypothesis that low vitamin D receptor (VDR) level causes intestinal vitamin D resistance and intestinal calcium (Ca) malabsorption. To do so, we examined vitamin D regulated duodenal Ca absorption and gene expression [transient receptor potential channel, vallinoid subfamily member 6 (TRPV6), 24-hydroxylase, calbindin D(9k) (CaBP) mRNA, and CaBP protein] in wild-type mice and mice with reduced tissue VDR levels [i.e. heterozygotes for the VDR gene knockout (HT)]. Induction of 24-hydroxylase mRNA levels by 1,25 dihydroxyvitamin D(3) [1,25(OH)(2) D(3)] injection was significantly reduced in the duodenum and kidney of HT mice in both time-course and dose-response experiments. TRPV6 and CaBP mRNA levels in duodenum were significantly induced after 1,25(OH)(2) D(3) injection, but there was no difference in response between wild-type and HT mice. Feeding a low-calcium diet for 1 wk increased plasma PTH, renal 1alpha-hydroxylase (CYP27B1) mRNA level, and plasma 1,25(OH)(2) D(3), and this response was greater in HT mice (by 88, 55, and 37% higher, respectively). In contrast, duodenal TRPV6 and CaBP mRNA were not higher in HT mice fed the low-calcium diet. However, the response of duodenal Ca absorption and CaBP protein to increasing 1,25(OH)(2) D(3) levels was blunted by 40% in HT mice. Our data show that low VDR levels lead to resistance of intestinal Ca absorption to 1,25(OH)(2) D(3), and this resistance may be due to a role for the VDR (and VDR level) in the translation of CaBP.
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Affiliation(s)
- Yurong Song
- Interdepartmental Nutrition Program and Department of Foods and Nutrition, Purdue University, 700 West State Street, West Lafayette, IN 47906-2059, USA
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Akhter S, Kutuzova GD, Christakos S, DeLuca HF. Calbindin D9k is not required for 1,25-dihydroxyvitamin D3-mediated Ca2+ absorption in small intestine. Arch Biochem Biophys 2006; 460:227-32. [PMID: 17224126 DOI: 10.1016/j.abb.2006.12.005] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 12/05/2006] [Accepted: 12/05/2006] [Indexed: 12/20/2022]
Abstract
The exact role of calbindin D9k in vitamin D-mediated calcium absorption has been debated but remains unsettled. In 129/OlaHsd mice, calbindin D9k was found highest in duodenum (36-50%) and kidney (24-34%) followed by stomach, lung and uterus. Age does not affect the relative distribution of calbindin D9k but it does decline with age in duodenum of both male and female 129/Ola mice. Recently, we produced a null calbindin D9k mutant 129/OlaHsd mouse; this mouse proved to be indistinguishable from the wild-type in phenotype and in a serum calcium level regardless of age or gender. We have now examined directly whether the mutant mouse can absorb calcium from the intestine in response to the active form of vitamin D. The calbindin D9k null mutant mouse is fully able to absorb calcium from the intestine in response to 1,25-dihydroxyvitamin D3. It is, therefore, clear that calbindin D9k is not required for vitamin D-induced intestinal calcium absorption.
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Affiliation(s)
- Shirin Akhter
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706-1544, USA
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Abstract
Backgrounds underlying age-related bone loss can be classified into two categories: systemic abnormality and osteoblast dysfunction. The former includes insufficiency of vitamin D or estrogen, causing a negative balance of calcium metabolism. We propose the contribution of an aging-suppressing gene, klotho, as a novel systemic factor, as a mouse deficient in the klotho gene exhibits multiple aging phenotypes including osteopenia with a low bone turnover. As a factor intrinsic to osteoblasts, we investigated the role of PPARgamma, a key regulator of adipocyte differentiation, based on the facts that osteoblasts and adipocytes share a common progenitor. Heterozygous PPARgamma-deficient mice exhibited high bone mass by stimulating osteoblastogenesis from bone marrow progenitors, and this effect became prominent with aging, indicating involvement of PPARgamma-dependent bone formation in the pathophysiology of age-related bone loss. The local environment of osteoblasts is mainly controlled by cytokines/growth factors, among which insulin-like growth factor-I (IGF-I) is the most possible candidate whose production and activity are decreased with aging. Bone phenotypes of deficient mice of insulin receptor substrates (IRS-1 and IRS-2), essential molecules for intracellular signaling of IGF-I, revealed that IRS-1 is essential to maintain bone turnover by up-regulating anabolic and catabolic functions of osteoblasts, while IRS-2 is needed to keep the predominance of the anabolic function over the catabolic function. A next task ahead of us will be to elucidate the network system of these factors underlying age-related osteoporosis.
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Affiliation(s)
- Hiroshi Kawaguchi
- Department of Sensory and Motor System Medicine, Faculty of Medicine, University of Tokyo, Tokyo, 113-8655, Japan.
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Brown AJ, Krits I, Armbrecht HJ. Effect of age, vitamin D, and calcium on the regulation of rat intestinal epithelial calcium channels. Arch Biochem Biophys 2005; 437:51-8. [PMID: 15820216 DOI: 10.1016/j.abb.2005.02.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Revised: 02/02/2005] [Indexed: 01/30/2023]
Abstract
Transepithelial transport of calcium involves uptake at the apical membrane, movement across the cell, and extrusion at the basolateral membrane. Active vitamin D metabolites regulate the latter two processes by induction of calbindin D and the plasma membrane ATPase (calcium pump), respectively. The expression of calbindin D and the calcium pump declines with age in parallel with transepithelial calcium transport. The apical uptake of calcium is thought to be mediated by the recently cloned calcium channels-CaT1 (or ECaC2, TRPV6) and CaT2 (or ECaC1, TRPV5). The purpose of these studies was to determine whether there were age-related changes in intestinal calcium channel regulation and to identify the dietary factors responsible for their regulation. Young (2 months) and adult (12 months) rats were fed either a high calcium or low calcium diet for 4 weeks. The low calcium diet significantly increased duodenal CaT1 and CaT2 mRNA levels in both age groups, but the levels in the adult were less than half that of the young. The changes in calcium channel expression with age and diet were significantly correlated with duodenal calcium transport and with calbindin D levels. To elucidate the relative roles of serum 1,25(OH)2D3 and calcium in the regulation of calcium channel expression, young rats were fed diets containing varying amounts of calcium and vitamin D. Dietary vitamin D or exogenous 1,25(OH)2D3 more than doubled CaT1 mRNA levels, and this regulation was independent of dietary or serum calcium. These findings suggest that the apical calcium channels, along with calbindin and the calcium pump, may play a role in intestinal calcium transport and its modulation by age, dietary calcium, and 1,25(OH)2D3.
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Affiliation(s)
- Alex J Brown
- Renal Division, Washington University School of Medicine, St. Louis, MO 63110, USA
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Russo de Boland A. Age-related changes in the response of intestinal cells to parathyroid hormone. Mech Ageing Dev 2004; 125:877-88. [PMID: 15563934 DOI: 10.1016/j.mad.2004.05.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The concept of the role(s) of parathyroid hormone (PTH), has expanded from that on acting on the classical target tissues, bone and kidney, to the intestine where its actions are of regulatory and developmental importance: regulation of intracellular calcium through modulation of second messengers and, activation of mitogenic cascades leading to cell proliferation. Several causes have been postulated to modify the hormone response in intestinal cells with ageing, among them, alterations of PTH receptor (PTHR1) binding sites, reduced expression of G proteins and hormone signal transduction changes. The current review summarizes the actual knowledge regarding the molecular and biochemical basis of age-impaired PTH receptor-mediated signaling in intestinal cells. A fundamental understanding of why PTH functions are impaired with age will enhance our understanding of its importance in intestinal cell physiology.
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Affiliation(s)
- Ana Russo de Boland
- Dpto. Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, 8000 Bahía Blanca, Argentina.
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Nordin BEC, Need AG, Morris HA, O'Loughlin PD, Horowitz M. Effect of age on calcium absorption in postmenopausal women. Am J Clin Nutr 2004; 80:998-1002. [PMID: 15447911 DOI: 10.1093/ajcn/80.4.998] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND It is assumed that calcium absorption decreases with age, but this is not well documented. We report a study that addresses this issue. OBJECTIVE The aim was to establish the extent and timing of any age-related change in calcium absorption in postmenopausal women. DESIGN We measured radiocalcium absorption (alpha) in 262 healthy postmenopausal women aged 40-87 y. We also measured the serum vitamin D metabolites, parathyroid hormone (PTH), and other biochemical variables. RESULTS Radiocalcium absorption decreased with age (P = 0.018); it was 28% lower in the 25 women aged >75 y than in the rest (P < 0.001). It was significantly related to serum 1,25-dihydroxyvitamin D [1,25(OH)(2)D] in the whole set and in both the younger and older subsets, but it was not related to either 25-dihydroxyvitamin D [25(OH)D] or PTH or to any other measured variable. No decrease in 1,25(OH)(2)D was seen with age to account for the decrease in calcium absorption, so radiocalcium absorption corrected for serum 1,25(OH)(2)D decreased significantly after age 75 y. On multivariate analysis, the serum 1,25(OH)(2)D concentration was a positive function of 25(OH)D (P < 0.001), albumin (P = 0.010), and PTH (P = 0.012) and a negative function of serum creatinine (P = 0.003). PTH was a negative function of calculated ionized calcium (P = 0.004) and 25(OH)D (P = 0.009) and a positive function of weight (P = 0.011) and age (P = 0.028). CONCLUSIONS A late age-related decrease in calcium absorption is seen in postmenopausal women in addition to the decline that occurs at menopause. This decrease could be due to a decline in either the active calcium transport or diffusion component of the calcium absorption system.
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Affiliation(s)
- B E Christopher Nordin
- Division of Clinical Biochemistry, Institute of Medical and Veterinary Science, Adelaide, Australia.
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Larsson B, Nemere I. Effect of growth and maturation on membrane-initiated actions of 1,25-dihydroxyvitamin D3?II: Calcium transport, receptor kinetics, and signal transduction in intestine of female chickens. J Cell Biochem 2003; 90:901-13. [PMID: 14624450 DOI: 10.1002/jcb.10696] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We recently reported (Larsson and Nemere [2003]: Endocrinology 144:1726) the effects of growth and maturation on 1,25(OH)2D3-membrane initiated effects in the intestine of male chickens. Here we extend our observations to studies on females with two stages of high calcium demand: growth (7-14 weeks) and egg laying (28-58 weeks). The rapid stimulatory effect of 130 pM 1,25(OH)2D3 on calcium transport was assessed as a physiological response in perfused duodena of 7-, 14-, 28-, and 58-week-old chickens, and determined to be 308%, 184%, 170%, and 153%, respectively, of corresponding controls after 40 min. Saturation analyses of [3H]1,25(OH)2D3 binding to nuclear vitamin D receptor (VDR) indicated an absence of cooperative binding, no changes in dissociation constant (Kd) with age, and an increase in maximum binding capacity (Bmax) between 7-week birds and older age groups. Analyses of saturable binding of [3H]1,25(OH)2D3 to the membrane associated rapid response steroid binding protein (1,25D3-MARRS bp) in basal lateral membranes (BLM), indicated cooperative binding, and an increase in both Bmax and Kd with age. No changes in the age-related expression of 1,25D3-MARRS bp were found, as judged by Western analyses, suggesting that a shift in ligand binding to lower affinity membrane components accounted for the increase in calculated Bmax. Basal levels of protein kinase C (PKC) activity decreased with age, as did hormone enhancement of activity. Basal levels of protein kinase A (PKA) activity remained constant with age, while the magnitude of hormone stimulation increased. Comparison of dose-response curves for ion transport and kinase activities in 7-week chicks suggested that PKC mediates phosphate transport while PKA mediates calcium transport. Thus, the age-related loss of calcium transport is most likely related to loss of PKC-mediated phosphate transport.
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Affiliation(s)
- Birgitta Larsson
- Utah State University, Department of Nutrition and Food Sciences and the Biotechnology and Genomics Research Center, Logan, Utah 84322-8700, USA
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Martini L, Wood RJ. Relative bioavailability of calcium-rich dietary sources in the elderly. Am J Clin Nutr 2002; 76:1345-50. [PMID: 12450902 DOI: 10.1093/ajcn/76.6.1345] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The recent increase in the dietary calcium recommendation from 800 to 1200 mg/d for persons aged > 51 y has made it important to identify alternative high-calcium dietary sources that the elderly can use in meeting their calcium requirement. OBJECTIVE We determined the bioavailability of calcium from 3 different sources: orange juice fortified with calcium-citrate malate, skim milk, and a calcium carbonate supplement. DESIGN Twelve subjects [9 women and 3 men with a mean (+/- SEM) age of 70 +/- 3 and 76 +/- 6 y, respectively] consumed low-calcium (300 mg/d) and high-calcium (1300 mg/d) diets for three 1-wk periods each during a 6-wk crossover study. The acute biochemical response to calcium from each of the 3 sources was assessed during a 4-h period after the initial breakfast meal of the high-calcium diet. RESULTS Postprandial suppression of serum parathyroid hormone did not differ significantly between the test meals containing calcium-fortified orange juice, the calcium carbonate supplement, and milk. This finding suggests that the calcium bioavailability from the 3 sources was equivalent. During the 1-wk high-calcium diet periods, fasting serum calcium increased by 3% (P < 0.0001), serum 1,25-dihydroxyvitamin D decreased by 20% (P < 0.0001), and a biomarker of bone resorption (serum N-telopeptide collagen cross-links) decreased by 14% (P < 0.02) compared with the low-calcium diet period. However, no differences among the supplemental calcium sources were found in these calcium-responsive measures or fasting serum parathyroid hormone concentration. CONCLUSIONS In elderly subjects, the calcium bioavailability of the 3 high-calcium dietary sources tested was equivalent, during both the acute postprandial and longer-term periods.
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Affiliation(s)
- Ligia Martini
- Mineral Bioavailability Laboratory, Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston
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Yamagishi N, Yukawa YA, Ishiguro N, Soeta S, Lee IH, Oboshi K, Yamada H. Expression of calbindin-D9k messenger ribonucleic acid in the gastrointestinal tract of dairy cattle. JOURNAL OF VETERINARY MEDICINE. A, PHYSIOLOGY, PATHOLOGY, CLINICAL MEDICINE 2002; 49:461-5. [PMID: 12489868 DOI: 10.1046/j.1439-0442.2002.00483.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The calcium demands of pregnancy and lactation are known to up-regulate expression of Calbindin-D9k (CaBP-9k) mRNA in the intestines. The gastrointestinal CaBP-9k mRNA expressions has not been studied in dairy cows, which are bound to experience several pregnancies and lactation stages. In this study, the CaBP-9k mRNA expression were examined in the gastrointestinal tract of Holstein dairy cattle by Northern blot analysis. Detectable expression of CaBP-9k mRNA was localized in the proximal portion of the small intestines. These expressions were higher at the most proximal region of the duodenum and gradually decreased distally. The duodenal CaBP-9k mRNA was detected in all dairy cattle from 0.4 to 83.4 months old, but was not detectable in foetuses. There were no significant correlations between the age and the levels of CaBP-9k mRNA expression or between the plasma 1,25-(OH)2D3 concentrations and the levels of CaBP-9k mRNA expression.
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Affiliation(s)
- N Yamagishi
- Department of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.
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Fleet JC, Eksir F, Hance KW, Wood RJ. Vitamin D-inducible calcium transport and gene expression in three Caco-2 cell lines. Am J Physiol Gastrointest Liver Physiol 2002; 283:G618-25. [PMID: 12181175 DOI: 10.1152/ajpgi.00269.2001] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The parental cell line (P) of Caco-2 cells and two clones, BBe and TC7, were studied at 11 days postconfluence to test the facilitated diffusion model of vitamin D-mediated intestinal calcium absorption (CaTx). Nuclear vitamin D receptor (nVDR) and calbindin D(9k) (CaBP) were measured by Western blot; 1,25-hydroxyvitamin D(3) 24-hydroxylase (CYP24), CaBP, plasma membrane Ca-ATPase (PMCA), and Ca transport channel (CaT1) mRNA levels were examined by RT-PCR; and net apical-to-basolateral CaTx was examined after treating cells with vehicle or 10 nM calcitriol for 8 (mRNA levels) or 48 h (protein, CaBP mRNA, CaTx). nVDR level was lowest in BBe (38% P value) and directly related to CYP24 induction (TC7 = P, which were 1.56 times greater than BBe). nVDR was inversely related to the vitamin D-induced levels of CaT1 mRNA, CaBP mRNA, PMCA mRNA, and net CaTx, with the highest induction seen in BBe. Basal CaBP mRNA (86 times greater than P) and protein levels were highest in TC7 cells and were not associated with higher net CaTx, suggesting CaBP may not be rate limiting for CaTx in these cells.
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Affiliation(s)
- James C Fleet
- Department of Foods and Nutrition, Purdue University, West Lafayette, Indiana 47906, USA.
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Van Cromphaut SJ, Dewerchin M, Hoenderop JG, Stockmans I, Van Herck E, Kato S, Bindels RJ, Collen D, Carmeliet P, Bouillon R, Carmeliet G. Duodenal calcium absorption in vitamin D receptor-knockout mice: functional and molecular aspects. Proc Natl Acad Sci U S A 2001; 98:13324-9. [PMID: 11687634 PMCID: PMC60869 DOI: 10.1073/pnas.231474698] [Citation(s) in RCA: 395] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Rickets and hyperparathyroidism caused by a defective vitamin D receptor (VDR) can be prevented in humans and animals by high calcium intake, suggesting that intestinal calcium absorption is critical for 1,25(OH)(2) vitamin D [1,25(OH)(2)D(3)] action on calcium homeostasis. We assessed the rate of serum (45)Ca accumulation within 10 min of oral gavage in two strains of VDR-knockout (KO) mice (Leuven and Tokyo KO) and observed a 3-fold lower area under the curve in both KO strains. Moreover, we evaluated the expression of intestinal candidate genes involved in transcellular calcium transport. The calcium transport protein1 (CaT1) was more abundantly expressed at mRNA level than the epithelial calcium channel (ECaC) in duodenum, but both were considerably reduced (CaT1>90%, ECaC>60%) in the two VDR-KO strains on a normal calcium diet. Calbindin-D(9K) expression was decreased only in the Tokyo KO, whereas plasma membrane calcium ATPase (PMCA(1b)) expression was normal in both VDR-KOs. In Leuven wild-type mice, a high calcium diet inhibited (>90%) and 1,25(OH)(2)D(3) injection or low calcium diet induced (6-fold) duodenal CaT1 expression and, to a lesser degree, ECaC and calbindin-D(9K) expression. In Leuven KO mice, however, high or low calcium intake decreased calbindin-D(9K) and PMCA(1b) expression, whereas CaT1 and ECaC expression remained consistently low on any diet. These results suggest that the expression of the novel duodenal epithelial calcium channels (in particular CaT1) is strongly vitamin D-dependent, and that calcium influx, probably interacting with calbindin-D(9K), should be considered as a rate-limiting step in the process of vitamin D-dependent active calcium absorption.
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Affiliation(s)
- S J Van Cromphaut
- Laboratory of Experimental Medicine and Endocrinology, Katholieke Universiteit Leuven, Leuven, B-3000 Belgium
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