151
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Kurosu H, Choi M, Ogawa Y, Dickson AS, Goetz R, Eliseenkova AV, Mohammadi M, Rosenblatt KP, Kliewer SA, Kuro-O M. Tissue-specific expression of betaKlotho and fibroblast growth factor (FGF) receptor isoforms determines metabolic activity of FGF19 and FGF21. J Biol Chem 2007; 282:26687-26695. [PMID: 17623664 PMCID: PMC2496965 DOI: 10.1074/jbc.m704165200] [Citation(s) in RCA: 592] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The fibroblast growth factor (FGF) 19 subfamily of ligands, FGF19, FGF21, and FGF23, function as hormones that regulate bile acid, fatty acid, glucose, and phosphate metabolism in target organs through activating FGF receptors (FGFR1-4). We demonstrated that Klotho and betaKlotho, homologous single-pass transmembrane proteins that bind to FGFRs, are required for metabolic activity of FGF23 and FGF21, respectively. Here we show that, like FGF21, FGF19 also requires betaKlotho. Both FGF19 and FGF21 can signal through FGFR1-3 bound by betaKlotho and increase glucose uptake in adipocytes expressing FGFR1. Additionally, both FGF19 and FGF21 bind to the betaKlotho-FGFR4 complex; however, only FGF19 signals efficiently through FGFR4. Accordingly, FGF19, but not FGF21, activates FGF signaling in hepatocytes that primarily express FGFR4 and reduces transcription of CYP7A1 that encodes the rate-limiting enzyme for bile acid synthesis. We conclude that the expression of betaKlotho, in combination with particular FGFR isoforms, determines the tissue-specific metabolic activities of FGF19 and FGF21.
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Affiliation(s)
- Hiroshi Kurosu
- Department of Pathology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Mihwa Choi
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Yasushi Ogawa
- Department of Pathology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Addie S Dickson
- Department of Pathology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Regina Goetz
- Department of Pharmacology, New York University School of Medicine, New York, New York 10016
| | - Anna V Eliseenkova
- Department of Pharmacology, New York University School of Medicine, New York, New York 10016
| | - Moosa Mohammadi
- Department of Pharmacology, New York University School of Medicine, New York, New York 10016
| | - Kevin P Rosenblatt
- Department of Pathology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Steven A Kliewer
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Makoto Kuro-O
- Department of Pathology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390.
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152
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The inorganic phosphate/inorganic pyrophosphate axis in the mineralization of cartilage and bone. ACTA ACUST UNITED AC 2007. [DOI: 10.1097/bco.0b013e328285dffc] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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153
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Six N, Septier D, Chaussain-Miller C, Blacher R, DenBesten P, Goldberg M. Dentonin, a MEPE fragment, initiates pulp-healing response to injury. J Dent Res 2007; 86:780-5. [PMID: 17652210 DOI: 10.1177/154405910708600818] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Phosphorylated extracellular matrix proteins, including matrix extracellular phosphoprotein (MEPE), are involved in the formation and mineralization of dental tissues. In this study, we evaluated the potential of Dentonin, a synthetic peptide derived from MEPE, to promote the formation of reparative dentin. Agarose beads, either soaked with Dentonin or unloaded, were implanted into the pulps of rat molars, and examined 8, 15, and 30 days after treatment. At day 8, Dentonin promoted the proliferation of pulp cells, as visualized by PCNA-labeling. RP59-positive osteoblast progenitors were located around the Dentonin-soaked beads. PCNA- and RP59-labeling were decreased at day 15, while osteopontin, weakly labeled at day 8, was increased at 15 days, but dentin sialoprotein was undetectable at any time. At 8 days, precocious reparative dentin formation occurred in pulps containing Dentonin-soaked beads, with formation slowing after 15 days. These results suggest that Dentonin affects primarily the initial cascade of events leading to pulp healing.
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Affiliation(s)
- N Six
- Laboratoire de Réparation et Remodelage des Tissus Orofaciaux, EA 2496, Groupe Matrices Extracellulaires et Biominéralisation, Faculté de Chirurgie Dentaire, Université Paris 5, 92120 Montrouge, France
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154
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155
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Ogawa Y, Kurosu H, Yamamoto M, Nandi A, Rosenblatt KP, Goetz R, Eliseenkova AV, Mohammadi M, Kuro-o M. BetaKlotho is required for metabolic activity of fibroblast growth factor 21. Proc Natl Acad Sci U S A 2007; 104:7432-7. [PMID: 17452648 PMCID: PMC1855074 DOI: 10.1073/pnas.0701600104] [Citation(s) in RCA: 477] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Indexed: 12/18/2022] Open
Abstract
Fibroblast growth factor 21 (FGF21) is a liver-derived endocrine factor that stimulates glucose uptake in adipocytes. Here, we show that FGF21 activity depends on betaKlotho, a single-pass transmembrane protein whose expression is induced during differentiation from preadipocytes to adipocytes. BetaKlotho physically interacts with FGF receptors 1c and 4, thereby increasing the ability of these FGF receptors to bind FGF21 and activate the MAP kinase cascade. Knockdown of betaKlotho expression by siRNA in adipocytes diminishes glucose uptake induced by FGF21. Importantly, administration of FGF21 into mice induces MAP kinase phosphorylation in white adipose tissue and not in tissues without betaKlotho expression. Thus, betaKlotho functions as a cofactor essential for FGF21 activity.
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Affiliation(s)
- Yasushi Ogawa
- *Department of Pathology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390; and
| | - Hiroshi Kurosu
- *Department of Pathology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390; and
| | - Masaya Yamamoto
- *Department of Pathology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390; and
| | - Animesh Nandi
- *Department of Pathology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390; and
| | - Kevin P. Rosenblatt
- *Department of Pathology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390; and
| | - Regina Goetz
- Department of Pharmacology, New York University School of Medicine, 550 First Avenue, MSB 425, New York, NY 10016
| | - Anna V. Eliseenkova
- Department of Pharmacology, New York University School of Medicine, 550 First Avenue, MSB 425, New York, NY 10016
| | - Moosa Mohammadi
- Department of Pharmacology, New York University School of Medicine, 550 First Avenue, MSB 425, New York, NY 10016
| | - Makoto Kuro-o
- *Department of Pathology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390; and
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156
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Roarke MC, Nguyen BD. PET/CT localization of phosphaturic mesenchymal neoplasm causing tumor-induced osteomalacia. Clin Nucl Med 2007; 32:300-1. [PMID: 17413579 DOI: 10.1097/01.rlu.0000257180.03964.51] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Michael C Roarke
- Department of Radiology, Mayo Clinic Scottsdale, Scottsdale, AZ 85259, USA.
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157
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Ariceta G, Langman CB. Growth in X-linked hypophosphatemic rickets. Eur J Pediatr 2007; 166:303-9. [PMID: 17171343 DOI: 10.1007/s00431-006-0357-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Accepted: 10/25/2006] [Indexed: 11/28/2022]
Abstract
Growth failure appears frequently in children with X-linked hypophosphatemic rickets (XLHR) due to hypophosphatemia, disease severity, body disproportion, and primary bone abnormality. Recombinant human growth hormone (rhGH) increases phosphate tubular reabsorption and phosphate level in blood and, thus, constitutes an attractive but controversial therapy in short children with XLHR, those efficacy was demonstrated in small uncontrolled series. Our aim was to report our experience regarding growth in XLHR. Twenty-seven children with XLHR--20 girls, seven boys--diagnosed at a median (md) of 1.46 years of age, (range 0.39-8.5 years), were studied at 10.12 years of age (1.58-18.56), md (range). All received oral treatment with phosphate and calcitriol. At the first visit, grouped Z-height was -1; (-4.58; 0.54) md (range). After 5 years' follow-up (0.92-15.6), Z-height was -0.91 (- 4.56; 0.17), not different from that at baseline (P = 0.465). In 16 children entirely controlled in our program upon presentation, a "catch up" phenomenon after the rickets had healed (P = 0.823) or throughout the long-term was not observed (P = 0.995). Eight patients had a Z-height </= -2SD at the last visit, and impaired linear growth was associated with age >2 years at diagnosis, male gender and non-adherence to treatment. Four children, all boys, received rhGH, and in two cases with sufficient follow up stature normalized. No rhGH side effects were observed, and phosphate and calcitriol doses remained stable. Linear growth failure appeared in a third of XLHR children. Efforts need to be made to reduce the age of diagnosis and to improve adherence to treatment. Treatment with rhGH should be considered early, after the rickets has been controlled, in those patients with impaired growth or delayed diagnosis.
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Affiliation(s)
- Gema Ariceta
- Division of Pediatric Kidney Diseases, Hospital Cruces, Vizcaya, Spain.
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158
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Julien M, Magne D, Masson M, Rolli-Derkinderen M, Chassande O, Cario-Toumaniantz C, Cherel Y, Weiss P, Guicheux J. Phosphate stimulates matrix Gla protein expression in chondrocytes through the extracellular signal regulated kinase signaling pathway. Endocrinology 2007; 148:530-7. [PMID: 17068135 PMCID: PMC2001233 DOI: 10.1210/en.2006-0763] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Whereas increasing evidence suggests that inorganic phosphate (Pi) may act as a signaling molecule in mineralization-competent cells, its mechanisms of action remain largely unknown. The aims of the present work were to determine whether Pi regulates expression of matrix Gla protein (MGP), a mineralization inhibitor, in growth plate chondrocytes and to identify the involved signaling pathways. Chondrogenic ATDC5 cells and primary growth plate chondrocytes were used. Messenger RNA and protein analyses were performed by quantitative PCR and Western blotting, respectively. The activation and role of MAPKs were, respectively, determined by Western blotting and the use of specific inhibitors. Immunohistological detection of ERK1/2 was performed in rib organ cultures from newborn mice. The results indicate that Pi markedly stimulates expression of MGP in ATDC5 cells and primary growth plate chondrocytes. Investigation of the involved intracellular signaling pathways reveals that Pi activates ERK1/2 in a cell-specific manner, because the stimulation was observed in ATDC5 and primary chondrocytes, MC3T3-E1 osteoblasts, and ST2 stromal cells, but not in L929 fibroblasts or C2C12 myogenic cells. Accordingly, immunohistological detection of ERK1/2 phosphorylation in rib growth plates revealed a marked signal in chondrocytes. Finally, a specific ERK1/2 inhibitor, UO126, blocks Pi-stimulated MGP expression in ATDC5 cells, indicating that ERK1/2 mediates, mainly, the effects of Pi. These data demonstrate, for the first time, that Pi regulates MGP expression in growth plate chondrocytes, thereby suggesting a key role for Pi and ERK1/2 in the regulation of bone formation.
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Affiliation(s)
- Marion Julien
- Laboratoire d'ingénierie ostéo-articulaire et dentaire
INSERM : U791 IFR26Université de NantesFaculté de Chirurgie Dentaire
1, Place Alexis Ricordeau
44042 NANTES CEDEX 1,FR
| | - David Magne
- Laboratoire de recherche sur les biomatériaux et les biotechnologies LR2B
INSERM : ERI2Université du Littoral Côte d'Opale62325 BOULOGNE SUR MER,FR
| | - Martial Masson
- Laboratoire d'ingénierie ostéo-articulaire et dentaire
INSERM : U791 IFR26Université de NantesFaculté de Chirurgie Dentaire
1, Place Alexis Ricordeau
44042 NANTES CEDEX 1,FR
| | - Malvyne Rolli-Derkinderen
- Physiopathologie et pharmacologie cellulaires et moléculaires
INSERM : U533 IFR26Université de NantesFaculté de Médecine (dpt Physiologie)
1, Rue Gaston Veil
44035 NANTES CEDEX 1,FR
| | - Olivier Chassande
- Biomatériaux et réparation tissulaire
INSERM : U443Université Victor Segalen - Bordeaux IIFR
| | - Chrystelle Cario-Toumaniantz
- Physiopathologie et pharmacologie cellulaires et moléculaires
INSERM : U533 IFR26Université de NantesFaculté de Médecine (dpt Physiologie)
1, Rue Gaston Veil
44035 NANTES CEDEX 1,FR
| | - Yan Cherel
- Développement et Pathologie du Tissu Musculaire
INRA : UMR703Ecole Nationale Vétérinaire de NantesFR
| | - Pierre Weiss
- Laboratoire d'ingénierie ostéo-articulaire et dentaire
INSERM : U791 IFR26Université de NantesFaculté de Chirurgie Dentaire
1, Place Alexis Ricordeau
44042 NANTES CEDEX 1,FR
| | - Jérôme Guicheux
- Laboratoire d'ingénierie ostéo-articulaire et dentaire
INSERM : U791 IFR26Université de NantesFaculté de Chirurgie Dentaire
1, Place Alexis Ricordeau
44042 NANTES CEDEX 1,FR
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159
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Foster BL, Popowics TE, Fong HK, Somerman MJ. Advances in defining regulators of cementum development and periodontal regeneration. Curr Top Dev Biol 2007; 78:47-126. [PMID: 17338915 DOI: 10.1016/s0070-2153(06)78003-6] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Substantial advancements have been made in defining the cells and molecular signals that guide tooth crown morphogenesis and development. As a result, very encouraging progress has been made in regenerating crown tissues by using dental stem cells and recombining epithelial and mesenchymal tissues of specific developmental ages. To date, attempts to regenerate a complete tooth, including the critical periodontal tissues of the tooth root, have not been successful. This may be in part due to a lesser degree of understanding of the events leading to the initiation and development of root and periodontal tissues. Controversies still exist regarding the formation of periodontal tissues, including the origins and contributions of cells, the cues that direct root development, and the potential of these factors to direct regeneration of periodontal tissues when they are lost to disease. In recent years, great strides have been made in beginning to identify and characterize factors contributing to formation of the root and surrounding tissues, that is, cementum, periodontal ligament, and alveolar bone. This review focuses on the most exciting and important developments over the last 5 years toward defining the regulators of tooth root and periodontal tissue development, with special focus on cementogenesis and the potential for applying this knowledge toward developing regenerative therapies. Cells, genes, and proteins regulating root development are reviewed in a question-answer format in order to highlight areas of progress as well as areas of remaining uncertainty that warrant further study.
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Affiliation(s)
- Brian L Foster
- Department of Periodontics, School of Dentistry, University of Washington, Seattle, Washington 98195, USA
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160
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GU G, KURATA K, CHEN Z, VÄÄNÄNEN KH. Osteocyte: a Cellular Basis for Mechanotransduction in Bone. ACTA ACUST UNITED AC 2007. [DOI: 10.1299/jbse.2.150] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Guoliang GU
- Institute of Biomedicine, Department of Anatomy, University of Turku
| | - Kosaku KURATA
- Department of Biorobotics, Faculty of Engineering, Kyushu Sangyo University
| | - Zhi CHEN
- Institute of Biomedicine, Department of Anatomy, University of Turku
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161
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Gal-Moscovici A, Sprague SM. Bone health in chronic kidney disease-mineral and bone disease. Adv Chronic Kidney Dis 2007; 14:27-36. [PMID: 17200041 DOI: 10.1053/j.ackd.2006.10.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Chronic kidney disease (CKD) is accompanied by disturbances in calcium, phosphate, vitamin D, and parathyroid hormone (PTH) homeostasis that play an important role in the pathophysiology of renal bone disease. The increased cardiovascular morbidity and mortality observed among patients with CKD has recently been recognized to be associated with these disturbances in mineral metabolism. Thus, disturbances in mineral metabolism observed in renal failure results in a multisystem disorder, making the development of a standardized definition of these disorders a top priority. Therefore, the Board of Directors of Kidney Disease: Improving Global Outcomes proposed to define the broader category of mineral disorders associated with CKD as CKD-mineral and bone disorder (CKD-MBD). This newly proposed definition will include the disorders of mineral metabolism, bone histology (renal osteodystrophy), and the extraskeletal manifestations such as vascular calcification. This new definition and stratification of disease should result in improvement not only in the clinical management of patients but also will facilitate the interpretation and translation of clinical research. Renal osteodystrophy is now considered as 1 component of this disorder and will be defined as a morphologic alteration only, based on unification of the histomorphometric definitions that will include parameters of turnover, mineralization, and volume. An internationally accepted classification system will enable the consensus for bone biopsy evaluation as well as for the role of biomarkers. This article will focus on the newly proposed definitions of bone disease as part of CKD-MBD, based on the complex pathophysiologic process underlying bone disease in CKD stages 2 to 5.
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Affiliation(s)
- Anca Gal-Moscovici
- Evanston Northwestern Healthcare, Northwestern University Feinberg School of Medicine, Evanston, IL 60201, USA
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162
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Ferrari S. Single gene mutations and variations affecting bone turnover and strength: a selective 2006 update. ACTA ACUST UNITED AC 2006. [DOI: 10.1138/20060240] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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163
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Kuro-o M. Klotho as a regulator of fibroblast growth factor signaling and phosphate/calcium metabolism. Curr Opin Nephrol Hypertens 2006; 15:437-41. [PMID: 16775459 DOI: 10.1097/01.mnh.0000232885.81142.83] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
PURPOSE OF REVIEW This review summarizes the most recent findings on Klotho in the regulation of fibroblast growth factor-23 (FGF23) signaling and phosphate/calcium homeostasis. RECENT FINDINGS The klotho gene encodes a single-pass transmembrane protein and functions as an aging-suppressor gene, which extends life span when overexpressed and accelerates the development of aging-like phenotypes when disrupted in mice. FGF23 is a hormone that suppresses phosphate reabsorption in renal proximal tubules. Recent studies have shown that Klotho mice and Fgf23 mice exhibit identical phenotypes including hyperphosphatemia and hypercalcemia in addition to the aging-like syndrome. This may be explained by the fact that Klotho binds to multiple FGF receptors and increases their affinity to FGF23. Another Klotho protein function is to activate transient receptor potential vanilloid-5 - a calcium channel involved in calcium reabsorption in the kidney. Klotho protein can modify sugar chains on transient receptor potential vanilloid-5 through its activity as a beta-glucuronidase, preventing the calcium channel from internalization and inactivation. SUMMARY Klotho protein binds to fibroblast growth factor receptors and functions as a regulator of FGF23 signaling. It also functions as an enzyme that modifies sugar chains of transient receptor potential vanilloid-5 and regulates its activity. Klotho is a multi-functional protein that regulates phosphate/calcium metabolism as well as aging.
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Affiliation(s)
- Makoto Kuro-o
- Department of Pathology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9072, USA.
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164
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Ozono K, Michigami T, Namba N, Nakajima S, Yamamoto T. Molecular bases of diseases characterized by hypophosphatemia and phosphaturia: new understanding. Clin Pediatr Endocrinol 2006; 15:129-35. [PMID: 24790333 PMCID: PMC4004864 DOI: 10.1297/cpe.15.129] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Accepted: 06/05/2006] [Indexed: 12/13/2022] Open
Abstract
Serum phosphate levels are regulated in both calcium-dependent and -independent fashions. Active vitamin D increases while PTH decreases serum phosphate levels in association with the elevation of serum calcium. On the other hand, a calcium-independent phosphaturic factor, historically called phosphatonin is believed to exert a physiological function based on findings in hereditary and tumor-induced diseases characterized by hypophosphatemia with normocalcemia. Among them, autosomal dominant hypophosphatemic rickets (ADHR) has contributed greatly to its elucidation because the gene responsible for ADHR encodes fibroblast growth factor 23 (FGF23) that has been found to have a phosphaturic effect. In addition, FGF23 has been proved to be involved in most cases of oncogenic osteomalacia and X-linked hypophosphatemic rickets that are also characterized by hypophosphatemia and normocalcemia. Moreover, familial tumoral calcinosis, which represents the metabolic mirror image of hypophosphatemic conditions, is caused by a loss-of-function mutation in the FGF23 gene in some patients. Very recently, hereditary hypophosphatemic rickets with hypercalciuria has been found to be caused by mutations in the SLC34A1 gene which encodes a type of sodium phosphate cotransporter. These findings may provide new strategies for treating patients with abnormal phosphate metabolism.
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Affiliation(s)
- Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Toshimi Michigami
- Department of Environmental Medicine, Osaka Medical Center and Institute for Maternal and Child Health, Osaka, Japan
| | - Noriyuki Namba
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan ; First Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Shigeo Nakajima
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
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165
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Masuda S, Jones G. Promise of vitamin D analogues in the treatment of hyperproliferative conditions. Mol Cancer Ther 2006; 5:797-808. [PMID: 16648549 DOI: 10.1158/1535-7163.mct-05-0539] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
1Alpha,25-dihydroxyvitamin D3 [1alpha,25-(OH)2D3; calcitriol] is best known as a hormone involved in calcium homeostasis but is also a potent antiproliferative agent in many cell types, particularly epithelial cells. 1Alpha,25(OH)2D3 mediates its actions through a classic steroid hormone-like transcriptional mechanism by influencing the expression of hundreds of genes. Effects of 1alpha,25(OH)2D3 have been observed on expression of cell cycle regulators, growth factors and their receptors, apoptotic machinery, metastatic potential, and angiogenesis; all of which have some effect on hyperproliferative conditions. This minireview focuses on the anticancer potential of 1alpha,25(OH)2D3 and its analogues by summarizing the promising data from animal and human trials of 1alpha,25(OH)2D3 and some of the more interesting synthetic vitamin D analogues in the treatment of a variety of different animal cancer models and in human patients with advanced cancer. Optimal administration of vitamin D analogues is only just being achieved with high-dose intermittent administration overcoming bioavailability and hypercalcemia problems and combination therapy with cytotoxic agents (taxols and cisplatins), antiresorptive agents (bisphosphonates), or cytochrome P450 inhibitors being attempted. Although the potential of vitamin D as an antiproliferative drug has been realized in the treatment of psoriasis and in parathyroid cell hyperplasia associated with secondary hyperparathyroidism, the search for an anticancer treatment incorporating a vitamin D analogue remains elusive.
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Affiliation(s)
- Sonoko Masuda
- Department of Biochemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6
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166
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Bhan I, Shah A, Holmes J, Isakova T, Gutierrez O, Burnett SM, Jüppner H, Wolf M. Post-transplant hypophosphatemia: Tertiary 'Hyper-Phosphatoninism'? Kidney Int 2006; 70:1486-94. [PMID: 16941023 DOI: 10.1038/sj.ki.5001788] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hypophosphatemia is a common complication of kidney transplantation. Tertiary hyperparathyroidism has long been thought to be the etiology, but hypophosphatemia can occur despite low parathyroid hormone (PTH) levels and can persist after high PTH levels normalize. Furthermore, even in the setting of normal allograft function, hypophosphatemia, and hyperparathyroidism, calcitriol levels remain inappropriately low following transplantation, suggesting that mechanisms other than PTH contribute. Fibroblast growth factor-23 (FGF-23) induces phosphaturia, inhibits calcitriol synthesis, and accumulates in chronic kidney disease. We performed a prospective, longitudinal study of 27 living donor transplant recipients to test the hypotheses that excessive FGF-23 accounts for hypophosphatemia and decreased calcitriol levels following kidney transplantation. Hypophosphatemia <2.5 mg/dl developed in 85% of subjects, including one who had previously undergone parathyroidectomy; 37% developed phosphate < or =1.5 mg/dl. The mean pre-transplant FGF-23 level was 1,218+/-542 RU/ml. Within the first week following transplantation, mean levels decreased to 557+/-579 RU/ml, which were still above normal. FGF-23 was independently associated with serum phosphate (P < 0.01), urinary excretion of phosphate (P < 0.01), and calcitriol levels (P < 0.01); PTH was not independently associated with any of these parameters. We calculated area under the curve for FGF-23 and PTH between the pre- and first post-transplant levels as a summary measure of early exposure to these phosphaturic hormones. An area under the FGF-23 curve greater than the median was associated with a relative risk of developing hypophosphatemia < or =1.5 mg/dl of 5.3 (P = 0.02) compared with lower levels. Increased area under the PTH curve was not associated with greater risk of hypophosphatemia. Excessive FGF-23 exposure in the early post-transplant period appears to be more strongly associated with post-transplant hypophosphatemia than PTH.
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Affiliation(s)
- I Bhan
- Renal Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
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167
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Abstract
BACKGROUND The study of a distinct group of renal phosphate wasting disorders with bone disease which comprise X-linked hypophosphatemic rickets (XLH), autosomal dominant hypophosphatemic rickets (ADHR) and tumour-induced osteomalacia (TIO) gave rise to the identification of different hormone-like peptides, also known as phosphatonins. These factors are responsible for the major disease features that characterize XLH, ADHR and TIO. Recent reports on one of these phosphatonins, fibroblast growth factor-23 (FGF-23), point to a general role of this factor in mineral ion metabolism. OBJECTIVES The main focus regards recent evidence implicating FGF-23 in normal and disordered mineral homeostasis with special emphasis on chronic kidney disease. The interactions of FGF-23 with phosphate, parathyroid hormone and vitamin D are discussed in detail. SUMMARY The FGF-23 has been shown to increase urinary phosphate excretion, inhibit bone mineralization and suppress 1,25-dihydroxy vitamin D(3)[1,25(OH)(2)D(3)], the main characteristics that XLH, ADHR and TIO have in common. Apart from its role in these phosphate wasting disorders serum FGF-23 is elevated in hypoparathyroidism and humoral hypercalcaemia of malignancy and responds to altered dietary phosphate and calcium supply in healthy subjects. The FGF-23 is also variably elevated in chronic kidney disease and associated secondary hyperparathyroidism where it correlates positively with serum phosphate and parathyroid hormone and negatively with 1,25(OH)(2)D(3). Such relationships, along with data from experimental studies, raise the question of whether FGF-23 contributes to the pathophysiology of chronic kidney disease.
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Affiliation(s)
- B Bielesz
- Institute of Physiology, Zurich, Switzerland.
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168
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Stewart I, Roddie C, Gill A, Clarkson A, Mirams M, Coyle L, Ward C, Clifton-Bligh P, Robinson BG, Mason RS, Clifton-Bligh RJ. Elevated serum FGF23 concentrations in plasma cell dyscrasias. Bone 2006; 39:369-76. [PMID: 16644301 DOI: 10.1016/j.bone.2006.01.163] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Accepted: 01/30/2006] [Indexed: 02/01/2023]
Abstract
Fibroblast growth factor 23 (FGF23) is now recognized as a key regulator of phosphate metabolism. Numerous reports have found elevated serum FGF23 concentrations in oncogenic osteomalacia associated with mesenchymal tumors. Hypophosphatemic osteomalacia more rarely occurs in non-mesenchymal tumors. We identified elevated serum FGF23 levels in one patient with chronic lymphatic leukemia (CLL) and hypophosphatemia, prompting us to examine FGF23 concentrations in other patients with B-cell neoplasms. FGF23 levels were elevated in several patients with myeloma and monoclonal gammopathy of undetermined significance (MGUS), and were significantly associated with serum paraprotein and beta-2 microglobulin concentrations in these patients. Hypophosphatemia was not observed even in those patients with elevated FGF23, and a weak positive correlation was noted between serum FGF23 and phosphate concentrations. Malignant plasma cells in bone marrow trephines from patients with myeloma showed cytoplasmic expression of FGF23, similar to the cytoplasmic localization of FGF23 already described in mesenchymal tumors associated with oncogenic osteomalacia. Our findings contribute to an expanding literature regarding abnormal FGF/FGF receptor-signaling in myeloma. The absence of hypophosphatemia in these cases suggests either that FGF23 produced by clonal B-cells lacks systemic bioactivity or that other factors contribute to maintain serum phosphate. We suggest that the relationship between FGF23 and skeletal disease associated with plasma cell dyscrasias deserves further study.
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Affiliation(s)
- Inge Stewart
- Cancer Genetics Department, Kolling Institute of Medical Research, Royal North Shore Hospital, St Leonards, NSW 2065, Australia
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169
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Abstract
The idiom renal osteodystrophy (ROD) represents a heterogeneous pattern of bone disturbances caused by chronic renal insufficiency and concomitant diseases. For the clinical decision of therapy it is most important to differentiate between high and low or adynamic turnover ROD because the therapeutically consequences of these two ends of the ROD spectrum are fundamentally different. Bone histology remains the gold standard for the exact classification of ROD. Serological markers of bone metabolism are not suited for the accurate nomenclature of ROD but are useful for the sequential follow up of ROD after a clear diagnosis has been made. Similarly, radiological diagnosis of ROD using dual energy X-ray absorptiometry (DEXA) or quantitative computer tomography scan (q-CT) is inaccurate and thus more suited for the routine follow up of established disease. Besides mineralization, bone strength and the rate of fractures are strongly determined by the architecture of the bone matrix. This information, however, is also only available on bone biopsy sections and cannot be estimated by non-invasive diagnostic methods. In summary, bone biopsy should be used more liberally for correct classification of bone disease. The sequential follow up and guidance of therapy success can be performed by non-invasive procedures such as biochemical bone marker determination in blood. X-ray imaging and densitometry is suitable only for sequential evaluation of osteoporosis.
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Affiliation(s)
- C Schwarz
- Medical University of Vienna, Vienna, Austria
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170
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Hecht J, Seitz V, Urban M, Wagner F, Robinson PN, Stiege A, Dieterich C, Kornak U, Wilkening U, Brieske N, Zwingman C, Kidess A, Stricker S, Mundlos S. Detection of novel skeletogenesis target genes by comprehensive analysis of a Runx2(-/-) mouse model. Gene Expr Patterns 2006; 7:102-12. [PMID: 16829211 DOI: 10.1016/j.modgep.2006.05.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Revised: 05/26/2006] [Accepted: 05/29/2006] [Indexed: 01/06/2023]
Abstract
Runx2 is an essential factor for skeletogenesis and heterozygous loss causes cleidocranial dysplasia in humans and a corresponding phenotype in the mouse. Homozygous Runx2-deficient mice lack hypertrophic cartilage and bone. We compared the expression profiles of E14.5 wildtype and Runx2(-/-) murine embryonal humeri to identify new transcripts potentially involved in cartilage and bone development. Seventy-one differentially expressed genes were identified by two independent oligonucleotide-microarray hybridizations and quantitative RT-PCR experiments. Gene Ontology analysis demonstrated an enrichment of the differentially regulated genes in annotations to terms such as extracellular, skeletal development, and ossification. In situ hybridization on E15.5 limb sections was performed for all 71 differentially regulated genes. For 54 genes conclusive in situ hybridization results were obtained and all of them showed skeletal expression. Co-expression with Runx2 was demonstrated for 44 genes. While 41 of the 71 differentially expressed genes have a known role in bone and cartilage, we identified 21 known genes that have not yet been implicated in skeletal development and 9 entirely new transcripts. Expression in the developing skeleton was demonstrated for 21 of these genes.
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Affiliation(s)
- J Hecht
- Max Planck Institute for Molecular Genetics, Ihnestr. 73, 14195 Berlin,Germany
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171
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Orimo H, Shimada T. Effects of phosphates on the expression of tissue-nonspecific alkaline phosphatase gene and phosphate-regulating genes in short-term cultures of human osteosarcoma cell lines. Mol Cell Biochem 2006; 282:101-8. [PMID: 16317517 DOI: 10.1007/s11010-006-1520-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2005] [Accepted: 08/01/2005] [Indexed: 10/25/2022]
Abstract
We studied the effects of phosphates on the expression of the human tissue-nonspecific alkaline phosphatase (TNSALP) gene and phosphate-regulating genes in short-term cultures of human osteoblastic osteosarcoma cell lines. When human osteosarcoma cell lines, SaOS-2, MG-63, and U(2)OS were cultured with 10 mM inorganic sodium dihydrogenphosphate, 10 mM beta-glycerophosphate, 250 microM pyridoxal phosphate, or 100 microM inorganic pyrophosphate, enzymatic activity of alkaline phosphatase began to increase at 72 h after addition of sodium dihydrogenphosphate and beta-glycerophosphate in SaOS-2 cells. Pyridoxal phosphate and pyrophosphate did not induce alkaline phosphatase activity. U(2)OS cells slightly reacted to beta-glycerophosphate, but MG-63 cells did not react on exposure to phosphates. In SaOS-2 cells, TNSALP mRNA measured by real-time RT-PCR reached a peak level at 72 h after the addition of beta-glycerophosphate. PHEX and MEPE mRNAs were also induced by beta-glycerophosphate. These results suggest that TNSALP, PHEX and MEPE were concordantly induced by beta-glycerophosphate on mineralisation.
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Affiliation(s)
- Hideo Orimo
- Department of Biochemistry and Molecular Biology, Nippon Medical School, 1-1-5 Sendagi, Tokyo 113-8602, Japan.
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172
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Parsonage MJ, Wilkins EGL, Snowden N, Issa BG, Savage MW. The development of hypophosphataemic osteomalacia with myopathy in two patients with HIV infection receiving tenofovir therapy. HIV Med 2006; 6:341-6. [PMID: 16156882 DOI: 10.1111/j.1468-1293.2005.00318.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report two cases in which osteomalacia developed in patients on tenofovir-containing highly active antiretroviral therapy (HAART) in the context of Fanconi syndrome with hypophosphataemia. Bone pain was the presenting feature and myopathy followed in one case. Disability was reversed with withdrawal of the drug and with mineral supplementation. The cases highlight the importance of considering the diagnosis of osteomalacia in patients treated with tenofovir. A possible association with incipient acute renal failure, particularly during nonsteroidal anti-inflammatory drug (NSAID) use, needs further investigation.
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Affiliation(s)
- M J Parsonage
- Department of Infectious Diseases and Tropical Medicine, North Manchester General Hospital, Crumpsall, Manchester, UK
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173
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Rendina D, Mossetti G, De Filippo G, Cioffi M, Strazzullo P. Fibroblast growth factor 23 is increased in calcium nephrolithiasis with hypophosphatemia and renal phosphate leak. J Clin Endocrinol Metab 2006; 91:959-63. [PMID: 16352682 DOI: 10.1210/jc.2005-1606] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT Nephrolithiasis affects about 10% of the population in industrialized countries, with calcium salts composing more than 80% of renal stones. A significant percentage of patients with calcium nephrolithiasis and normal parathyroid function show hypophosphatemia and reduced renal phosphate reabsorption (i.e. a renal phosphate leak). OBJECTIVES The objective of the study was to compare serum levels of fibroblast growth factor 23 (FGF23), a regulator of phosphate homeostasis, in 110 recurrent stone formers with or without renal phosphate leak, six patients affected by X-linked hypophosphatemic rickets, five patients affected by oncogenic osteomalacia, and 60 unrelated healthy controls. DESIGN This was a prospective interventional study. METHODS Renal phosphate leak was identified based on the occurrence of idiopathic hypophosphatemia [serum phosphate concentration < 2.50 mg/dl (<0.80 mmol/liter)] and reduced renal threshold phosphate concentration [<2.2 mg/liter (<0.70 mmol/liter)]. RESULTS In 22 stone formers with renal phosphate leak, serum FGF23 concentration was significantly higher as compared with 88 stone formers without renal phosphate leak and with controls [83.3 (65.6-101.1) vs. 32.1 (26.8-37.4) and 24.5 (19.8-29.1) reference units (RU)/ml, respectively]. Stone formers with renal phosphate leak showed lower FGF23, compared with patients with oncogenic osteomalacia and X-linked hypophosphatemic rickets [572.3 (235.9-908.7) RU/ml]. Among stone formers and controls, serum FGF23 concentration displayed a strong inverse association with serum phosphate (r = -0.784, P = 0.009) and the rate of tubular phosphate reabsorption (r = -0.791, P = 0.008). CONCLUSIONS In our study population, renal phosphate leak affected 20% of stone formers and was strongly associated with increased serum FGF23 concentration.
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Affiliation(s)
- Domenico Rendina
- Department of Clinical and Experimental Medicine, Università Federico II, Via S. Pansini, 5-80131 Naples, Italy
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174
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Vaisbich MH, Koch VH. Hypophosphatemic rickets: results of a long-term follow-up. Pediatr Nephrol 2006; 21:230-4. [PMID: 16252097 DOI: 10.1007/s00467-005-2077-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Revised: 06/28/2005] [Accepted: 07/07/2005] [Indexed: 01/31/2023]
Abstract
This study reports the benefits and side effects of conventional treatment, phosphate and calcitriol supplementation in patients with heritable hypophosphatemic rickets and a long-term follow-up, median of 60.9 months. The group is composed of 17 patients (ten girls). Sixteen patients presented with bone pain and/or deformities, and in one patient the diagnosis was radiological. All the patients had increased alkaline phosphatase, hypophosphatemia, decreased fractional phosphate tubular reabsorption (TRP) and maximum tubular phosphate reabsorption/glomerular filtration rate ratio (TPO4/GFR). Ten of 17 patients had metabolic acidosis, which was corrected only with the conventional treatment. Potassium citrate was prescribed to the patients who developed hypercalciuria. Excluding one patient with pulmonary dysfunction, the remaining 16 patients were divided into two groups according to the age at treatment onset (T0): group I (GI) > or =4 years (n =9) and GII <4 years (n =7). GI and GII had similar follow-up periods and treatment protocols. Seven out of nine GI patients underwent orthopedic surgery, in contrast to none of GII. Anthropometric data results showed that within each group there is no difference in weight and stature z -score at T0 and at the end of the observation (Tf), but, when both groups are compared, GII shows higher z-score for stature at T0 (p <0.05) and at Tf (p <0.05). Nephrocalcinosis developed in three cases and correlated with hypercalciuria (p <0.001) and dose of calcitriol (p =0.03). In conclusion, higher stature z-score is associated with early treatment. A careful protocol is recommended to detect such complications as nephrocalcinosis. We suggest potassium citrate for patients with hypercalciuria to avoid calcium precipitation.
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Affiliation(s)
- Maria Helena Vaisbich
- Pediatric Nephrology Unit, Instituto da Crianca Hospital das Clinicas, Faculdade de Medicina da Universidade de Sao Paulo, 04105-001 Sao Paulo, Brazil.
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175
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Kurosu H, Ogawa Y, Miyoshi M, Yamamoto M, Nandi A, Rosenblatt KP, Baum MG, Schiavi S, Hu MC, Moe OW, Kuro-o M. Regulation of fibroblast growth factor-23 signaling by klotho. J Biol Chem 2006; 281:6120-3. [PMID: 16436388 PMCID: PMC2637204 DOI: 10.1074/jbc.c500457200] [Citation(s) in RCA: 1006] [Impact Index Per Article: 55.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The aging suppressor gene Klotho encodes a single-pass transmembrane protein. Klotho-deficient mice exhibit a variety of aging-like phenotypes, many of which are similar to those observed in fibroblast growth factor-23 (FGF23)-deficient mice. To test the possibility that Klotho and FGF23 may function in a common signal transduction pathway(s), we investigated whether Klotho is involved in FGF signaling. Here we show that Klotho protein directly binds to multiple FGF receptors (FGFRs). The Klotho-FGFR complex binds to FGF23 with higher affinity than FGFR or Klotho alone. In addition, Klotho significantly enhanced the ability of FGF23 to induce phosphorylation of FGF receptor substrate and ERK in various types of cells. Thus, Klotho functions as a cofactor essential for activation of FGF signaling by FGF23.
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Affiliation(s)
- Hiroshi Kurosu
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Yasushi Ogawa
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Masayoshi Miyoshi
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Masaya Yamamoto
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Animesh Nandi
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Kevin P. Rosenblatt
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Michel G. Baum
- Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Susan Schiavi
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Ming-Chang Hu
- Applied Genomics, Genzyme Corporation, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Orson W. Moe
- Applied Genomics, Genzyme Corporation, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Makoto Kuro-o
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
- To whom correspondence should be addressed: Dept. of Pathology, University of Texas Southwestern Medical Center at Dallas, 6000 Harry Hines Blvd., Dallas, TX 75390-9072. Tel.: 214-648-4018; Fax: 214-648-4070; E-mail:
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176
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Razzaque MS, Sitara D, Taguchi T, St-Arnaud R, Lanske B. Premature aging-like phenotype in fibroblast growth factor 23 null mice is a vitamin D-mediated process. FASEB J 2006; 20:720-2. [PMID: 16436465 PMCID: PMC2899884 DOI: 10.1096/fj.05-5432fje] [Citation(s) in RCA: 251] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Fibroblast growth factor 23 null mice (Fgf-23-/-) have a short lifespan and show numerous biochemical and morphological features consistent with premature aging-like phenotypes, including kyphosis, severe muscle wasting, hypogonadism, osteopenia, emphysema, uncoordinated movement, T cell dysregulation, and atrophy of the intestinal villi, skin, thymus, and spleen. Furthermore, increased vitamin D activities in homozygous mutants are associated with severe atherosclerosis and widespread soft tissue calcifications; ablation of vitamin D activity from Fgf-23-/- mice, by genetically deleting the 1alpha(OH)ase gene, eliminates atherosclerosis and ectopic calcifications and significantly rescues premature aging-like features of Fgf-23-/- mice, resulting in prolonged survival of Fgf-23-/-/1alpha(OH)ase-/- double mutants. Our results indicate a novel role of Fgf-23 in developing premature aging-like features through regulating vitamin D homeostasis. Finally, our data support a new model of interactions among Fgf-23, vitamin D, and klotho, a gene described as being associated with premature aging process.
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Affiliation(s)
- Mohammed S. Razzaque
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts
| | - Despina Sitara
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts
| | - Takashi Taguchi
- Department of Pathology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | | | - Beate Lanske
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts
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177
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Kazama JJ, Gejyo F, Shigematsu T, Fukagawa M. Role of circulating fibroblast growth factor 23 in the development of secondary hyperparathyroidism. Ther Apher Dial 2005; 9:328-30. [PMID: 16076376 DOI: 10.1111/j.1744-9987.2005.00291.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It would be useful to predict the future development of hyperparathyroidism before treatment with active vitamin D agents. Fibroblast growth factor 23 (FGF23) is a newly identified humoral phosphaturic factor. Positive correlation was found between parathyroid function and serum FGF23 levels in dialysis patients. Interestingly, FGF23 levels showed even better correlation with intact parathyroid hormone (iPTH) levels 2 years after the sample collection for the FGF23 measurement. In long-term dialysis patients with mild secondary hyperparathyroidism, serum FGF23 level was the best screening test to discriminate patients with future advanced secondary hyperparathyroidism within 2 years. In dialysis patients with advanced secondary hyperparathyroidism, the pretreatment FGF23 levels, as well as iPTH levels, significantly affected the outcome of calcitriol therapy. Thus, the measurement of serum FGF23 level is a promising laboratory examination to predict the future development of secondary hyperparathyroidism. The mechanism of this phenomenon, however, remains to be revealed.
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Affiliation(s)
- Junichiro J Kazama
- Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
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178
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Abstract
Hereditary hypophosphatemic rickets groups together X-linked hypophosphatemic rickets (XLH), autosomal dominant hypophosphatemic rickets (ADHR) and hereditary hypophosphatemic rickets with hypercalciuria (HHRH, autosomal recessive). Clinical and biological characteristics and treatment depend on specific etiology. Mutations causing hereditary hypophosphatemic rickets involve PHEX located on Xp11.22 for XLH and FGF-23 located on 12p13 for ADHR. The gene involved in HHRH remains unknown: candidates may encode proteins that modulate phosphate transporter expression or activity. Others forms of rickets must be ruled out: acquired hypophosphatemia due to oncogenic osteomalacia, X-linked recessive hypophosphatemic rickets or Dent's disease, and hereditary 1, 25-dihydroxyvitamin D-resistant rickets with a defect either in the 1-alpha-hydroxylase gene (pseudo-vitamin D deficiency rickets, PDDR) or in the vitamin D receptor (hereditary vitamin D-resistant rickets, HVDRR).
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Affiliation(s)
- F-L Vélayoudom-Céphise
- Service d'endocrinologie et métabolisme, Clinique Marc Linquette, CHRU de Lille (59). flvelayoudom@ tiscali.fr
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179
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Kolek OI, Hines ER, Jones MD, LeSueur LK, Lipko MA, Kiela PR, Collins JF, Haussler MR, Ghishan FK. 1alpha,25-Dihydroxyvitamin D3 upregulates FGF23 gene expression in bone: the final link in a renal-gastrointestinal-skeletal axis that controls phosphate transport. Am J Physiol Gastrointest Liver Physiol 2005; 289:G1036-42. [PMID: 16020653 DOI: 10.1152/ajpgi.00243.2005] [Citation(s) in RCA: 290] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Fibroblast growth factor (FGF)23 is a phosphaturic hormone that decreases circulating 1alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] and elicits hypophosphatemia, both of which contribute to rickets/osteomalacia. It has been shown recently that serum FGF23 increases after treatment with renal 1,25(OH)(2)D(3) hormone, suggesting that 1,25(OH)(2)D(3) negatively feedback controls its levels by inducing FGF23. To establish the tissue of origin and the molecular mechanism by which 1,25(OH)(2)D(3) increases circulating FGF23, we administered 1,25(OH)(2)D(3) to C57BL/6 mice. Within 24 h, these mice displayed a dramatic elevation in serum immunoreactive FGF23, and the expression of FGF23 mRNA in bone was significantly upregulated by 1,25(OH)(2)D(3), but there was no effect in several other tissues. Furthermore, we treated rat UMR-106 osteoblast-like cells with 1,25(OH)(2)D(3), and real-time PCR analysis revealed a dose- and time-dependent stimulation of FGF23 mRNA concentrations. The maximum increase in FGF23 mRNA was 1,024-fold at 10(-7) M 1,25(OH)(2)D(3) after 24-h treatment, but statistically significant differences were observed as early as 4 h after 1,25(OH)(2)D(3) treatment. In addition, using cotreatment with actinomycin D or cycloheximide, we observed that 1,25(OH)(2)D(3) regulation of FGF23 gene expression occurs at the transcriptional level, likely via the nuclear vitamin D receptor, and is dependent on synthesis of an intermediary transfactor. These results indicate that bone is a major site of FGF23 expression and source of circulating FGF23 after 1,25(OH)(2)D(3) administration or physiological upregulation. Our data also establish FGF23 induction by 1,25(OH)(2)D(3) in osteoblasts as a feedback loop between these two hormones that completes a kidney-intestine-bone axis that mediates phosphate homeostasis.
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Affiliation(s)
- Olga I Kolek
- Dept. of Pediatrics, Steele Children's Research Center, University of Arizona Health Sciences Center, Tucson, AZ 85724, USA
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180
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Abstract
Phosphate plays a key role in several biological processes. In recent years, new insights have been obtained into the regulation of the phosphate metabolism, including a growing amount of evidence suggesting that factors other than parathyroid hormone (PTH) and vitamin D are involved in maintaining the phosphate balance. A new class of phosphate-regulating factors, the so-called "phosphatonins," have been shown to be important in phosphate-wasting diseases. However, the role of the phosphatonins in the normal human homeostasis remains to be established. The incidence of hypophosphatemia in selected patient series can be more than 20%, with clinical sequelae ranging from mild to life threatening. Only when combined with phosphate depletion does hypophosphatemia become clinically significant. The factors that are involved in the phosphate homeostasis, the pathophysiology, the relevance in patient care, the clinical manifestations, and an appropriate management of phosphate depletion are discussed in this review.
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Affiliation(s)
- André Gaasbeek
- Department of General Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands.
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181
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Inagaki T, Choi M, Moschetta A, Peng L, Cummins CL, McDonald JG, Luo G, Jones SA, Goodwin B, Richardson JA, Gerard RD, Repa JJ, Mangelsdorf DJ, Kliewer SA. Fibroblast growth factor 15 functions as an enterohepatic signal to regulate bile acid homeostasis. Cell Metab 2005; 2:217-25. [PMID: 16213224 DOI: 10.1016/j.cmet.2005.09.001] [Citation(s) in RCA: 1348] [Impact Index Per Article: 70.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Revised: 08/01/2005] [Accepted: 09/01/2005] [Indexed: 02/06/2023]
Abstract
The liver and intestine play crucial roles in maintaining bile acid homeostasis. Here, we demonstrate that fibroblast growth factor 15 (FGF15) signals from intestine to liver to repress the gene encoding cholesterol 7alpha-hydroxylase (CYP7A1), which catalyzes the first and rate-limiting step in the classical bile acid synthetic pathway. FGF15 expression is stimulated in the small intestine by the nuclear bile acid receptor FXR and represses Cyp7a1 in liver through a mechanism that involves FGF receptor 4 (FGFR4) and the orphan nuclear receptor SHP. Mice lacking FGF15 have increased hepatic CYP7A1 mRNA and protein levels and corresponding increases in CYP7A1 enzyme activity and fecal bile acid excretion. These studies define FGF15 and FGFR4 as components of a gut-liver signaling pathway that synergizes with SHP to regulate bile acid synthesis.
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Affiliation(s)
- Takeshi Inagaki
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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182
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Biber J, Gisler SM, Hernando N, Murer H. Protein/protein interactions (PDZ) in proximal tubules. J Membr Biol 2005; 203:111-8. [PMID: 15986090 DOI: 10.1007/s00232-005-0738-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2004] [Revised: 02/10/2005] [Indexed: 11/29/2022]
Affiliation(s)
- J Biber
- Institute of Physiology, University of Zurich, Switzerland.
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183
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Inoue Y, Segawa H, Kaneko I, Yamanaka S, Kusano K, Kawakami E, Furutani J, Ito M, Kuwahata M, Saito H, Fukushima N, Kato S, Kanayama HO, Miyamoto KI. Role of the vitamin D receptor in FGF23 action on phosphate metabolism. Biochem J 2005; 390:325-31. [PMID: 15885032 PMCID: PMC1184586 DOI: 10.1042/bj20041799] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Revised: 04/25/2005] [Accepted: 05/10/2005] [Indexed: 11/17/2022]
Abstract
FGF23 (fibroblast growth factor 23) is a novel phosphaturic factor that influences vitamin D metabolism and renal re-absorption of Pi. The goal of the present study was to characterize the role of the VDR (vitamin D receptor) in FGF23 action using VDR(-/-) (VDR null) mice. Injection of FGF23M (naked DNA encoding the R179Q mutant of human FGF23) into VDR(-/-) and wildtype VDR(+/+) mice resulted in an elevation in serum FGF23 levels, but had no effect on serum calcium or parathyroid hormone levels. In contrast, injection of FGF23M resulted in significant decreases in serum Pi levels, renal Na/Pi co-transport activity and type II transporter protein levels in both groups when compared with controls injected with mock vector or with FGFWT (naked DNA encoding wild-type human FGF23). Injection of FGF23M resulted in a decrease in 25-hydroxyvitamin D 1a-hydroxylase mRNA levels in VDR(-/-) and VDR(+/+) mice, while 25-hydroxyvitamin D 24-hydroxylase mRNA levels were significantly increased in FGF23M-treated animals compared with mock vector control- or FGF23WT-treated animals. The degree of 24-hydroxylase induction by FGF23M was dependent on the VDR, since FGF23M significantly reduced the levels of serum 1,25(OH)2D3 [1,25-hydroxyvitamin D3] in VDR(+/+) mice, but not in VDR(-/-) mice. We conclude that FGF23 reduces renal Pi transport and 25-hydroxyvitamin D 1a-hydroxylase levels by a mechanism that is independent of the VDR. In contrast, the induction of 25-hydroxyvitamin D 24-hydroxylase and the reduction of serum 1,25(OH)2D3 levels induced by FGF23 are dependent on the VDR.
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Key Words
- fibroblast growth factor 23
- kidney
- phosphate transport
- vitamin d receptor
- adhr, autosomal dominant hypophosphataemic rickets
- bbmv, brush-border membrane vesicle
- fgf, fibroblast growth factor
- fgf23m, naked dna encoding the r179q mutant of human fgf23
- fgf23wt, naked dna encoding wild-type human fgf23
- gapdh, glyceraldehyde-3-phosphate dehydrogenase
- 1α(oh)ase, 25-hydroxyvitamin d3 1α-hydroxylase
- 24(oh)ase, 25-hydroxyvitamin d 24-hydroxylase
- 1,25(oh)2d3, 1,25-dihydroxyvitamin d3
- pth, parathyroid hormone
- rt-pcr, reverse transcription–pcr
- vdr, vitamin d receptor
- xlh, x-linked hypophosphataemia
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Affiliation(s)
- Yoshio Inoue
- *Department of Molecular Nutrition, Institute of Health Bioscience, The University of Tokushima Graduate School, Kuramoto-cho 3, Tokushima 770-8503, Japan
- †Department of Urology, The University of Tokushima School of Medicine, 3-18-15, Kuramoto-Cho, Tokushima 770-8503, Japan
| | - Hiroko Segawa
- *Department of Molecular Nutrition, Institute of Health Bioscience, The University of Tokushima Graduate School, Kuramoto-cho 3, Tokushima 770-8503, Japan
| | - Ichiro Kaneko
- *Department of Molecular Nutrition, Institute of Health Bioscience, The University of Tokushima Graduate School, Kuramoto-cho 3, Tokushima 770-8503, Japan
| | - Setsuko Yamanaka
- *Department of Molecular Nutrition, Institute of Health Bioscience, The University of Tokushima Graduate School, Kuramoto-cho 3, Tokushima 770-8503, Japan
| | | | - Eri Kawakami
- *Department of Molecular Nutrition, Institute of Health Bioscience, The University of Tokushima Graduate School, Kuramoto-cho 3, Tokushima 770-8503, Japan
| | - Junya Furutani
- *Department of Molecular Nutrition, Institute of Health Bioscience, The University of Tokushima Graduate School, Kuramoto-cho 3, Tokushima 770-8503, Japan
| | - Mikiko Ito
- *Department of Molecular Nutrition, Institute of Health Bioscience, The University of Tokushima Graduate School, Kuramoto-cho 3, Tokushima 770-8503, Japan
| | - Masashi Kuwahata
- *Department of Molecular Nutrition, Institute of Health Bioscience, The University of Tokushima Graduate School, Kuramoto-cho 3, Tokushima 770-8503, Japan
| | - Hitoshi Saito
- ‡Chugai Pharmaceutical Co. Ltd., Gotenba 412-8513, Japan
| | | | - Shigeaki Kato
- §Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Hiro-omi Kanayama
- †Department of Urology, The University of Tokushima School of Medicine, 3-18-15, Kuramoto-Cho, Tokushima 770-8503, Japan
| | - Ken-ichi Miyamoto
- *Department of Molecular Nutrition, Institute of Health Bioscience, The University of Tokushima Graduate School, Kuramoto-cho 3, Tokushima 770-8503, Japan
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184
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Cho HY, Lee BH, Kang JH, Ha IS, Cheong HI, Choi Y. A clinical and molecular genetic study of hypophosphatemic rickets in children. Pediatr Res 2005; 58:329-33. [PMID: 16055933 DOI: 10.1203/01.pdr.0000169983.40758.7b] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
X-linked hypophosphatemic rickets (XLH), autosomal dominant hypophosphatemic rickets, hereditary hypophosphatemic rickets with hypercalciuria, and tumor-induced osteomalacia share clinical and biochemical features, and are collectively referred to as hypophosphatemic rickets (HR). Recently, the molecular bases of HR were elucidated. A review of medical records and mutational analyses of the PHEX and FGF23 genes were performed on 17 unrelated Korean children with HR. The male-to-female ratio was 3:14, and 5 patients were familial. Initial laboratory tests revealed typical features of HR. Seven different PHEX mutations were detected in 8 patients: 2 missense mutations, 2 nonsense mutations, and 3 short deletions. No functional FGF23 mutation was detected in any patient. Patients with the PHEX mutation tended to have more severe skeletal disease than those without. Of the patients with this mutation, no genotype-phenotype correlation and no gene dosage effect were noted. Treatment with vitamin D and phosphate resulted in only a partial growth improvement in most cases, and was frequently complicated by hypercalciuria, hypercalcemia, nephrocalcinosis, or hyperparathyroidism. Renal glycosuria was detected in six cases and was associated with more severe skeletal disease. We conclude that current HR treatment is not fully safe or effective, and that close monitoring of treatment effectiveness and for complications should be performed during long-term treatment. No genotype-phenotype correlation in XLH was detected in this study, but a large-scaled study on this topic is warranted. The large proportion of patients with a normal genetic study suggests the possibility of other causative gene(s).
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Affiliation(s)
- Hee Y Cho
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul 110-744, Korea
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185
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Razzaque MS, St-Arnaud R, Taguchi T, Lanske B. FGF-23, vitamin D and calcification: the unholy triad. Nephrol Dial Transplant 2005; 20:2032-5. [PMID: 16030043 DOI: 10.1093/ndt/gfh991] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Mohammed S Razzaque
- Department of Oral and Developmental Biology, Research and Educational Building, Room 312, Harvard School of Dental of Medicine, 190 Longwood Ave, Boston, MA 02115, USA.
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186
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Matsumoto N, Jo OD, Shih RNJ, Yanagawa N. Altered cathepsin D metabolism in PHEX antisense human osteoblast cells. Biochem Biophys Res Commun 2005; 332:248-53. [PMID: 15896324 DOI: 10.1016/j.bbrc.2005.04.116] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2005] [Accepted: 04/17/2005] [Indexed: 11/16/2022]
Abstract
X-linked hypophosphatemia (XLH), the most common form of hereditary rickets, is caused by loss-of-function mutations of PHEX gene in osteoblast cells, leading to rachitic bone disease and hypophosphatemia. Available evidence today indicates that the bone defect in XLH is caused not only by hypophosphatemia and altered vitamin D metabolism, but also by locally released osteoblastic mineralization inhibitory factor(s), referred to as minhibin. In our present study, we found that suppression of PHEX expression by PHEX antisense in human osteoblast cells caused an increase in cathepsin D expression at protein, but not mRNA, levels. This was associated with a decrease in cathepsin D degradation and an increased cathepsin D release into culture media. Our results also showed that lowering cathepsin D activity in antisense cell conditioned media abolished their inhibitory effect on osteoblast cell calcification, suggesting the involvement of cathepsin D in mediating the minhibin activity of the antisense cell conditioned media.
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Affiliation(s)
- Naoko Matsumoto
- Medical and Research Services, GLAVAHS at Sepulveda, Sepulveda, CA 91343, USA
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187
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Matsumoto N, Jo OD, Shih RNJ, Brochmann EJ, Murray SS, Hong V, Yanagawa J, Yanagawa N. Increased cathepsin D release by Hyp mouse osteoblast cells. Am J Physiol Endocrinol Metab 2005; 289:E123-32. [PMID: 15958652 DOI: 10.1152/ajpendo.00562.2004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The X-linked hypophosphatemia (XLH), the most common form of hereditary rickets, is caused by loss-of-function mutations of PHEX (phosphate-regulating gene with homology to endopeptidases on the X chromosome) leading to rachitic bone disease and hypophosphatemia. Available evidence today indicates that the bone defect in XLH is caused not only by hypophosphatemia and altered vitamin D metabolism but also by factor(s) locally released by osteoblast cells (ObCs). The identity of these ObC-derived pathogenic factors remains unclear. In our present study, we report our finding of a prominent protein in the culture media derived from ObC of the hypophosphatemic (Hyp) mice, a murine homolog of human XLH, which was identified as the murine procathepsin D (Cat D). By metabolic labeling studies, we further confirmed that Hyp mouse ObCs released greater amount of Cat D into culture media. This increased Cat D release by Hyp mouse ObCs was unlikely to be due to nonspecific cell damage or heterogeneous cell population and was found to be associated with an increased Cat D expression at the protein level, possibly due to a reduced Cat D degradation. However, we were not able to detect a direct effect of PHEX protein on Cat D cleavage. In support of the involvement of Cat D in mediating the inhibitory effect of Hyp mouse ObC-conditioned media on ObC calcification, we found that exposure to Cat D inhibited ObC (45)Ca incorporation and that inhibition of Cat D abolished the inhibitory effect of Hyp mouse-conditioned media on ObC calcification. In conclusion, results from our present study showed that Hyp mouse ObCs release a greater amount of Cat D, which may contribute to the inhibitory effect of Hyp mouse ObC-conditioned media on ObC mineralization.
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Affiliation(s)
- Naoko Matsumoto
- Medical and Research Services, Greater Los Angeles Veterans Affairs Healthcare System at Sepulveda, CA, USA
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188
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Erben RG, Mayer D, Weber K, Jonsson K, Jüppner H, Lanske B. Overexpression of human PHEX under the human beta-actin promoter does not fully rescue the Hyp mouse phenotype. J Bone Miner Res 2005; 20:1149-60. [PMID: 15940367 DOI: 10.1359/jbmr.050212] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2004] [Revised: 01/29/2005] [Accepted: 02/18/2005] [Indexed: 12/13/2022]
Abstract
UNLABELLED XLH in humans and the Hyp phenotype in mice are caused by inactivating Phex mutations. Overexpression of human PHEX under the human beta-actin promoter in Hyp mice rescued the bone phenotype almost completely, but did not affect phosphate homeostasis, suggesting that different, possibly independent, pathophysiological mechanisms contribute to hyperphosphaturia and bone abnormalities in XLH. INTRODUCTION Mutations in PHEX, a phosphate-regulating gene with homologies to endopeptidases on the X chromosome, are responsible for X-linked hypophosphatemia (XLH) in humans, and its mouse homologs, Hyp, Phex(Hyp-2J), Phex(Hyp-Duk), Gy, and Ska1. PHEX is thought to inactivate a phosphaturic factor, which may be fibroblast growth factor 23 (FGF)-23. Consistent with this hypothesis, FGF-23 levels were shown to be elevated in most patients with XLH and in Hyp mice. The aim of this study was, therefore, to examine whether transgenic overexpression of PHEX under the human beta-actin promoter would rescue the Hyp phenotype. MATERIALS AND METHODS We tested this hypothesis by generating two mouse lines expressing human PHEX under the control of a human beta-actin promoter (PHEX-tg). With the exception of brain, RT-PCR analyses showed transgene expression in all tissues examined. PHEX protein, however, was only detected in bone, muscle, lung, skin, and heart. To assess the role of the mutant PHEX, we crossed female heterozygous Hyp mice with male heterozygous PHEX-tg mice to obtain wildtype (WT), PHEX-tg, Hyp, and Hyp/PHEX-tg offspring, which were examined at 3 months of age. RESULTS PHEX-tg mice exhibited normal bone and mineral ion homeostasis. Hyp mice showed the known phenotype with reduced body weight, hypophosphatemia, hyperphosphaturia, and rickets. Hyp/PHEX-tg mice had almost normal body weight relative to WT controls, showed a dramatic improvement in femoral BMD, almost normal growth plate width, and, despite remaining disturbances in bone mineralization, almost normal bone architecture and pronounced improvements of osteoidosis and of halo formation compared with Hyp mice. However, Hyp and Hyp/PHEX-tg mice had comparable reductions in tubular reabsorption of phosphate and were hypophosphatemic relative to WT controls. CONCLUSION Our data suggest that different, possibly independent, pathophysiological mechanisms contribute to renal phosphate wasting and bone abnormalities in Hyp and XLH.
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Affiliation(s)
- Reinhold G Erben
- Institute of Physiology, Physiological Chemistry and Animal Nutrition, Ludwig Maximilians University, Munich, Germany
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189
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Beraud G, Perimenis P, Velayoudom FL, Wemeau JL, Vantyghem MC. [Genetic hypophosphatemia: recent advances in physiopathogenic concept]. ANNALES D'ENDOCRINOLOGIE 2005; 66:109-16. [PMID: 15959411 DOI: 10.1016/s0003-4266(05)81707-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Renal proximal tubular reabsorption of phosphate and intestinal absorption both regulate phosphate homeostasis. Brush-border membrane Npt2a cotransporter is the key element in proximal tubular P (i) reabsorption. Inactivating mutations of Npt2a cause bone demineralisation and urolithiasis. An excess of a phosphaturic factor, called "Phosphatonin", could modulate phosphate reabsorption by inhibition on Npt2a. Inactivating mutation of PHEX, an endopeptidase-membrane coding gene, is responsible for X-linked Hypophosphatemia (XLH), because of an impaired degradation of phosphatonine by PHEX product. Autosomic Dominant Hypophosphatemic Rickets (ADHR) is explained by a mutation preventing FGF23 (one of the best identified phosphatonines) from cleavage. According recent data, FGF23, MEPE (Matrix Extracellular Phosphoglycoprotein) et FRP4 (frizzled related protein-4) are 3 putative "phosphatonines".
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Affiliation(s)
- G Beraud
- Service d'Endocrinologie et Métabolisme, 6, rue du Pr. Laguesse, Centre hospitalo-universitaire, 59037 Lille Cedex, France
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190
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Ito M, Sakai Y, Furumoto M, Segawa H, Haito S, Yamanaka S, Nakamura R, Kuwahata M, Miyamoto KI. Vitamin D and phosphate regulate fibroblast growth factor-23 in K-562 cells. Am J Physiol Endocrinol Metab 2005; 288:E1101-9. [PMID: 15671080 DOI: 10.1152/ajpendo.00502.2004] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Fibroblast growth factor-23 (FGF-23) has been recently identified as playing an important pathophysiological role in phosphate homeostasis and vitamin D metabolism. To elucidate the precise physiological regulation of FGF-23, we characterized the mouse FGF-23 5'-flanking region and analyzed its promoter activity. The 5'-flanking region of the mouse FGF-23 gene contained a TFIID site (TATA box) and several putative transcription factor binding sites, including MZF1, GATA-1 and c-Ets-1 motifs, but it did not contain the typical sequences of the vitamin D response element. Plasmids encoding 554-bp (pGL/-0.6), 364-bp (pGL/-0.4) and 200-bp (pGL/-0.13) promoter regions containing the TFIID element and +1-bp fragments drove the downstream expression of a luciferase reporter gene in transfection assays. We also found that FGF-23 mRNA was expressed in K-562 erythroleukemia cell lines but not in MC3T3-E1, Raji, or Hep G2 human carcinoma cells. Treatment with 1,25-dihydroxyvitamin D3 in the presence of high phosphate markedly stimulated pGL/-0.6 activity, but calcium had no effect. In addition, the plasma FGF-23 levels were affected by the dietary and plasma inorganic phosphate concentrations. Finally, the levels of plasma FGF-23 in vitamin D receptor-null mice were significantly lower than in wild-type mice. The presents study demonstrated that vitamin D and the plasma phosphate level are important regulators of the transcription of the mouse FGF-23 gene.
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Affiliation(s)
- Mikiko Ito
- Department of Molecular Nutrition, Institute of Health Biosciences, The Univ. of Tokushima Graduate School, Kuramoto-cho 3-18-15, Tokushima, Japan
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191
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Tebben PJ, Kalli KR, Cliby WA, Hartmann LC, Grande JP, Singh RJ, Kumar R. Elevated fibroblast growth factor 23 in women with malignant ovarian tumors. Mayo Clin Proc 2005; 80:745-51. [PMID: 15948297 DOI: 10.1016/s0025-6196(11)61528-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE To determine whether fibroblast growth factor 23 (FGF23) concentrations are altered in women with ovarian cancers in which FGF physiology is known to be abnormal. PATIENTS AND METHODS Between May 2002 and September 2003 at the Mayo Clinic in Rochester, Minn, plasma or serum FGF23 concentrations were measured in 39 healthy women and in 14 with benign ovarian tumors, 14 with early-stage ovarian cancer, and 13 with advanced-stage ovarian cancer. Immunohistochemistry using anti-human FGF23 antibodies was performed on tissue from benign masses and advanced-stage tumors. RESULTS Serum or plasma FGF23 concentrations were significantly higher in women with advanced-stage ovarian cancer compared with concentrations in women with early-stage ovarian cancer or benign disease or in healthy women. A significant positive correlation was seen between serum iFGF23 and cFGF23 concentrations and stage of disease. Serum iFGF23 and cFGF23 concentrations were positively correlated with serum phosphorus among women with ovarian cancer. No patients with elevated iFGF23 or cFGF23 concentrations had hypophosphatemia. Immunohistochemistry detected FGF23 tissue staining in malignant ovarian cancer cells. CONCLUSION Serum or plasma FGF23 concentrations are elevated in patients with advanced-stage epithellal ovarian cancer without reductions in serum phosphate concentrations. The presence of elevated FGF23 concentrations in patients with an ovarian mass should suggest advanced-stage disease.
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Affiliation(s)
- Peter J Tebben
- Department of Pediatric and Adolescent Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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192
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193
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Gutierrez O, Isakova T, Rhee E, Shah A, Holmes J, Collerone G, Jüppner H, Wolf M. Fibroblast growth factor-23 mitigates hyperphosphatemia but accentuates calcitriol deficiency in chronic kidney disease. J Am Soc Nephrol 2005; 16:2205-15. [PMID: 15917335 DOI: 10.1681/asn.2005010052] [Citation(s) in RCA: 693] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Hyperphosphatemia, calcitriol deficiency, and secondary hyperparathyroidism (SHPT) are common complications of chronic kidney disease (CKD). Fibroblast growth factor-23 (FGF-23) is a novel phosphaturic hormone that also inhibits renal 1alpha-hydroxylase activity and thus may be involved in the pathogenesis of SHPT. Several hypotheses were tested: that FGF-23 increases as renal function declines; is linearly associated with serum phosphate levels; is associated with increased phosphaturia independent of parathyroid hormone (PTH); and is associated with decreased calcitriol levels independent of renal function, hyperphosphatemia, and vitamin D stores. FGF-23, PTH, 25(OH)D3, calcitriol, calcium, phosphate, and urinary fractional excretion of phosphate (Fe(PO4)) were measured in 80 CKD patients. Multiple linear regression was used to test the hypotheses. FGF-23 and PTH were inversely associated with estimated GFR (eGFR), whereas calcitriol levels were linearly associated with eGFR. Hyperphosphatemia and hypocalcemia were present in only 12 and 6% of patients, respectively, all of whose eGFR was <30. Increased Fe(PO4) was associated with decreased eGFR, and both increased FGF-23 and PTH were independently associated with increased Fe(PO4). Increased FGF-23 and decreased 25(OH)D3 were independent predictors of decreased calcitriol, but the effects on calcitriol levels of renal function itself and hyperphosphatemia were completely extinguished by adjusting for FGF-23. It is concluded that FGF-23 levels increase early in CKD before the development of serum mineral abnormalities and are independently associated with serum phosphate, Fe(PO4), and calcitriol deficiency. Increased FGF-23 may contribute to maintaining normal serum phosphate levels in the face of advancing CKD but may worsen calcitriol deficiency and thus may be a central factor in the early pathogenesis of SHPT.
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Affiliation(s)
- Orlando Gutierrez
- Department of Medicine Internal Medicine Residency Training Program, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
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194
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Sitara D, Razzaque MS, Hesse M, Yoganathan S, Taguchi T, Erben RG, Jüppner H, Lanske B. Homozygous ablation of fibroblast growth factor-23 results in hyperphosphatemia and impaired skeletogenesis, and reverses hypophosphatemia in Phex-deficient mice. Matrix Biol 2005; 23:421-32. [PMID: 15579309 PMCID: PMC2894977 DOI: 10.1016/j.matbio.2004.09.007] [Citation(s) in RCA: 363] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2004] [Revised: 09/24/2004] [Accepted: 09/24/2004] [Indexed: 11/16/2022]
Abstract
Fibroblast growth factor-23 (FGF-23), a recently identified molecule that is mutated in patients with autosomal dominant hypophosphatemic rickets (ADHR), appears to be involved in the regulation of phosphate homeostasis. Although increased levels of circulating FGF-23 were detected in patients with different phosphate-wasting disorders such as oncogenic osteomalacia (OOM) and X-linked hypophosphatemia (XLH), it is not yet clear whether FGF-23 is directly responsible for the abnormal regulation of mineral ion homeostasis and consequently bone development. To address some of these unresolved questions, we generated a mouse model, in which the entire Fgf-23 gene was replaced with the lacZ gene. Fgf-23 null (Fgf-23-/-) mice showed signs of growth retardation by day 17, developed severe hyperphosphatemia with elevated serum 1,25(OH)2D3 levels, and died by 13 weeks of age. Hyperphosphatemia in Fgf-23-/- mice was accompanied by skeletal abnormalities, as demonstrated by histological, molecular, and various other morphometric analyses. Fgf-23-/-) mice had increased total-body bone mineral content (BMC) but decreased bone mineral density (BMD) of the limbs. Overall, Fgf-23-/- mice exhibited increased mineralization, but also accumulation of unmineralized osteoid leading to marked limb deformities. Moreover, Fgf-23-/- mice showed excessive mineralization in soft tissues, including heart and kidney. To further expand our understanding regarding the role of Fgf-23 in phosphate homeostasis and skeletal mineralization, we crossed Fgf-23-/- animals with Hyp mice, the murine equivalent of XLH. Interestingly, Hyp males lacking both Fgf-23 alleles were indistinguishable from Fgf-23/-/ mice, both in terms of serum phosphate levels and skeletal changes, suggesting that Fgf-23 is upstream of the phosphate regulating gene with homologies to endopeptidases on the X chromosome (Phex) and that the increased plasma Fgf-23 levels in Hyp mice (and in XLH patients) may be at least partially responsible for the phosphate imbalance in this disorder.
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Affiliation(s)
- Despina Sitara
- Department of Oral and Developmental Biology, The Forsyth Institute, Harvard School of Dental Medicine, 140 The Fenway, Boston, MA, 02115, USA
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195
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David JP, Mehic D, Bakiri L, Schilling AF, Mandic V, Priemel M, Idarraga MH, Reschke MO, Hoffmann O, Amling M, Wagner EF. Essential role of RSK2 in c-Fos-dependent osteosarcoma development. J Clin Invest 2005; 115:664-72. [PMID: 15719069 PMCID: PMC548699 DOI: 10.1172/jci22877] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2004] [Accepted: 01/04/2005] [Indexed: 12/19/2022] Open
Abstract
Inactivation of the growth factor-regulated S6 kinase RSK2 causes Coffin-Lowry syndrome in humans, an X-linked mental retardation condition associated with progressive skeletal abnormalities. Here we show that mice lacking RSK2 develop a progressive skeletal disease, osteopenia due to impaired osteoblast function and normal osteoclast differentiation. The phenotype is associated with decreased expression of Phex, an endopeptidase regulating bone mineralization. This defect is probably not mediated by RSK2-dependent phosphorylation of c-Fos on serine 362 in the C-terminus. However, in the absence of RSK2, c-Fos-dependent osteosarcoma formation is impaired. The lack of c-Fos phosphorylation leads to reduced c-Fos protein levels, which are thought to be responsible for decreased proliferation and increased apoptosis of transformed osteoblasts. Therefore, RSK2-dependent stabilization of c-Fos is essential for osteosarcoma formation in mice and may also be important for human osteosarcomas.
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196
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Nakashima M, Iohara K, Ishikawa M, Ito M, Tomokiyo A, Tanaka T, Akamine A. Stimulation of reparative dentin formation by ex vivo gene therapy using dental pulp stem cells electrotransfected with growth/differentiation factor 11 (Gdf11). Hum Gene Ther 2005; 15:1045-53. [PMID: 15610605 DOI: 10.1089/hum.2004.15.1045] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Dental pulp progenitor/stem cells have the capacity to differentiate into odontoblasts and they provide a potential for dentin repair and regeneration by gene therapy. To develop a successful ex vivo gene therapy to induce reparative dentin formation rapidly and effectively after treatment of caries, we developed a three-dimensional pellet culture system of pulp cells electrotransfected with growth/differentiation factor 11 (Gdf11). The viability after electrotransfection was more than 85%, and the efficiency was about 70% as determined by flow cytometry. After 10 days of culture, the total amount of type I and type III collagen was 3-fold higher in the pEGFP-Gdf11-transfected pellet than in the control. Real-time RT-PCR analysis demonstrated that the expression of markers of odontoblast differentiation (alkaline phosphatase, dentin matrix protein 1 [Dmp1], dentin sialophosphoprotein [Dspp], enamelysin, and phosphate-regulating gene with homologies to endopeptidases on X-chromosome [Phex]) was increased in the pEGFP-Gdf11-transfected pellet compared with the control on day 14. On the basis of this in vitro evaluation, an in vivo investigation in the dog was performed. Autogenous transplantation of Gdf11-transfected cells cultured as a pellet on amputated pulp stimulated reparative dentin formation. Thus, Gdf11 gene therapy may be potentially used in endodontic treatment in dentistry.
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Affiliation(s)
- Misako Nakashima
- Division of Oral Rehabilitation, Department of Clinical Oral Molecular Biology, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
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197
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Abstract
Disturbances in calcium and phosphorus metabolism are almost invariable consequences of chronic kidney disease (CKD). Because the capacity to regulate calcium and phosphorus metabolism becomes compromised progressively as kidney function declines, calcium and phosphorus homeostasis is disrupted and serum calcium or phosphorus levels are perturbed in many patients with CKD. The level of interest in, and concerns about, abnormalities in calcium and phosphorus metabolism among patients with CKD has increased substantially in recent years. Strategies for clinical management are being revised, and recent recommendations differ substantially from those used previously with a renewed emphasis on safety.
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Affiliation(s)
- William G Goodman
- Division of Nephrology, Department of Medicine, David Geffen School of Medicine at the University of California at Los Angeles, University of California at Los Angeles Medical Center, CA 90095, USA.
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198
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Dailey L, Ambrosetti D, Mansukhani A, Basilico C. Mechanisms underlying differential responses to FGF signaling. Cytokine Growth Factor Rev 2005; 16:233-47. [PMID: 15863038 DOI: 10.1016/j.cytogfr.2005.01.007] [Citation(s) in RCA: 482] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Fibroblast growth factors (FGFs) are key regulators of several developmental processes in which cell fate and differentiation to various tissue lineages are determined. The importance of the proper spatial and temporal regulation of FGF signals is evident from human and mouse genetic studies which show that mutations leading to the dysregulation of FGF signals cause a variety of developmental disorders including dominant skeletal diseases and cancer. The FGF ligands signal via a family of receptor tyrosine kinases and, depending on the cell type or stage of maturation, produce diverse biological responses that include proliferation, growth arrest, differentiation or apoptosis. A central issue in FGF biology is to understand how these diverse cellular responses are determined and how similar signaling inputs can generate distinct patterns of gene expression that govern the specificity of the cellular response. In this review we draw upon studies from the past fifteen years and attempt to construct a molecular picture of the different levels of regulation by which such specific cellular responses could be achieved by FGF signals. We discuss whether specificity could lie in the nature of the ligand, the particular receptor, the signal transduction pathways utilized, or the transcriptional regulation of specific genes. Finally, we also discuss how the interplay of FGF signals with other signaling systems could contribute to the cellular response. In particular we focus on the interaction with the Wnt pathway since FGF/Wnt cross-talk is emerging as an important nexus in regulating a variety of biological processes.
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Affiliation(s)
- Lisa Dailey
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
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199
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Kazama JJ, Sato F, Omori K, Hama H, Yamamoto S, Maruyama H, Narita I, Gejyo F, Yamashita T, Fukumoto S, Fukagawa M. Pretreatment serum FGF-23 levels predict the efficacy of calcitriol therapy in dialysis patients. Kidney Int 2005; 67:1120-5. [PMID: 15698453 DOI: 10.1111/j.1523-1755.2005.00178.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND The predictor for the result of calcitriol therapy would be useful in the clinical practice of secondary hyperparathyroidism. Fibroblast growth factor-23 (FGF-23) is a newly found circulating phosphaturic factor. Its circulating level is elevated in uremia. METHODS Dialysis patients with plasma intact parathyroid hormone (iPTH) levels greater than 300 pg/mL were included in the study. Calcitriol was intravenously injected three times a week. The patients whose plasma iPTH levels dropped below 300 pg/mL within 24 weeks were defined as those who had been successfully treated. A sandwich enzyme-linked immunosorbent assay (ELISA) system that detects human FGF-23 was applied. RESULTS Sixty-two patients were analyzed. The pretreatment FGF-23 levels were related to the iPTH levels, calcium x phosphate product levels, and history of active vitamin D therapy. The pretreatment FGF-23, iPTH, and calcium levels were lower in the patients who would be successfully treated with calcitriol. A logistic regression study revealed that the pretreatment iPTH and FGF-23 levels significantly affected the therapy results. Analyses using a receiver-operated curve revealed that FGF-23 was the best screening test for identifying patients with future refractory response to calcitriol therapy. The treatment would be successful in 88.2% of those with FGF-23 </=9860 ng/L and iPTH </=591 pg/mL, while it would be successful in only 4.2% of those with FGF-23 >9860 ng/L and iPTH >591 pg/mL. CONCLUSION Pretreatment serum FGF-23 levels were a good indicator in predicting the response to calcitriol therapy. The measurement of serum FGF-23 levels, especially in combination with iPTH levels, is a promising laboratory examination for the clinical practice of secondary hyperparathyroidism.
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Affiliation(s)
- Junichiro J Kazama
- Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
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200
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Ferrari SL, Bonjour JP, Rizzoli R. Fibroblast growth factor-23 relationship to dietary phosphate and renal phosphate handling in healthy young men. J Clin Endocrinol Metab 2005; 90:1519-24. [PMID: 15613425 DOI: 10.1210/jc.2004-1039] [Citation(s) in RCA: 375] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The renal handling of inorganic phosphate (Pi) is controlled not only by PTH, but also by hitherto undetermined mechanisms dependent on phosphate intake. Recently, fibroblast growth factor (FGF)-23 was identified as a novel phosphaturic factor in tumor-induced osteomalacia and autosomal-dominant hypophosphatemic rickets. We hypothesized that phosphate intake could influence FGF-23 concomitantly to the changes in renal Pi handling. Twenty-nine healthy males were subjected to a 5-d low-phosphate diet and a phosphate binder, followed by a high-phosphate diet including supplements. Concomitant modifications in calcium intake allowed minimizing PTH changes in response to dietary phosphate. Serum FGF-23 levels significantly decreased on the low-phosphate diet, then increased with the oral phosphate load. Changes in FGF-23 were positively correlated with changes in 24-h urinary Pi excretion and negatively correlated with changes in the maximal tubular reabsorption of Pi and 1,25(OH)(2)D(3) (calcitriol), whereas PTH was not. In multivariate analysis, changes in FGF-23 remained the most significantly correlated to changes in 1,25(OH)(2)D(3) and maximal tubular reabsorption of Pi. Moreover, FGF-23 was positively correlated to serum osteocalcin, a marker of osteoblastic activity. In summary, FGF-23 was inversely related to renal Pi transport and serum calcitriol levels in healthy young men. These data suggest that FGF-23 may be implicated in the physiological regulation of Pi homeostasis in response to dietary phosphate changes, independent of PTH.
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Affiliation(s)
- Serge L Ferrari
- Service of Bone Diseases, Geneva University Hospital, 24 rue Micheli-du-Crest, Geneva 1211, Switzerland.
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