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Pasaoglu OT, Senelmis A, Helvaci O, Derici U, Pasaoglu H. FGF23, alpha-Klotho and vitamin D mediated calcium-phosphate metabolism in haemodialysis patients. J Med Biochem 2021; 40:160-166. [PMID: 33776565 PMCID: PMC7982292 DOI: 10.5937/jomb0-27408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 08/26/2020] [Indexed: 11/16/2022] Open
Abstract
Background Klotho is a prote˝in that acts as a co-receptor for FGF23. FGF23-Klotho axis has great importance regarding the regulation of mineral metabolism by kidneys. In this study, we analysed FGF23, Klotho, 1,25-dihydroxyvitamin D3, 25-hydroxyvitamin D, parathormone, Calcium and Phosphate levels of haemodialysis patients in order to investigate the nature of the mineral metabolism disruption in chronic kidney diseases. Methods Sixty haemodialysis patients and 34 healthy controls were included in the study. Serum iFGF, cFGF, and soluble Klotho were analysed using ELISA kits. Moreover, 1,25-dihydroxyvitamin D3 was determined using LCMS/MS. Calcium, phosphate, iPTH and 25-hydroxyvitamin D were measured using autoanalyzers. Results In haemodialysis patients, iFGF23, cFGF23, iPTH and P levels were significantly higher, and 1,25-dihydroxyvitamin D3, Klotho and Ca levels were significantly lower compared with the control group. There was no significant difference in the 25-hydroxyvitamin D levels. Conclusions Our study showed that lack of sufficient amounts of Klotho is crucial for mineral metabolism disruptions seen as a complication of chronic kidney diseases. Despite the high levels of the hormone, FGF23 is unable to accomplish its function properly, likely due to deteriorated kidney function in haemodialysis patients.
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Affiliation(s)
- Ozge Tugce Pasaoglu
- Gazi University, Faculty of Health Sciences, Department of Nutrition and Dietetics, Ankara, Turkey
| | - Ayse Senelmis
- Gazi University, Faculty of Medicine, Department of Medical Biochemistry, Ankara, Turkey
| | - Ozant Helvaci
- Gazi University, Faculty of Medicine, Department of Internal Medicine, Section of Nephrology, Ankara, Turkey
| | - Ulver Derici
- Gazi University, Faculty of Medicine, Department of Internal Medicine, Section of Nephrology, Ankara, Turkey
| | - Hatice Pasaoglu
- Gazi University, Faculty of Medicine, Department of Medical Biochemistry, Ankara, Turkey
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Uchida K, Tanaka Y, Ichikawa H, Watanabe M, Mitani S, Morita K, Fujii H, Ishikawa M, Yoshino G, Okinaga H, Nagae G, Aburatani H, Ikeda Y, Susa T, Tamamori-Adachi M, Fukusato T, Uozaki H, Okazaki T, Iizuka M. An Excess of CYP24A1, Lack of CaSR, and a Novel lncRNA Near the PTH Gene Characterize an Ectopic PTH-Producing Tumor. J Endocr Soc 2017; 1:691-711. [PMID: 29264523 PMCID: PMC5686629 DOI: 10.1210/js.2017-00063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 04/25/2017] [Indexed: 12/11/2022] Open
Abstract
Thus far, only 23 cases of the ectopic production of parathyroid hormone (PTH) have been reported. We have characterized the genome-wide transcription profile of an ectopic PTH-producing tumor originating from a retroperitoneal histiocytoma. We found that the calcium-sensing receptor (CaSR) was barely expressed in the tumor. Lack of CaSR, a crucial braking apparatus in the presence of both intraparathyroid and, probably, serendipitous PTH expression, might contribute strongly to the establishment and maintenance of the ectopic transcriptional activation of the PTH gene in nonparathyroid cells. Along with candidate drivers with a crucial frameshift mutation or copy number variation at specific chromosomal areas obtained from whole exome sequencing, we identified robust tumor-specific cytochrome P450 family 24 subfamily A member 1 (CYP24A1) overproduction, which was not observed in other non–PTH-expressing retroperitoneal histiocytoma and parathyroid adenoma samples. We then found a 2.5-kb noncoding RNA in the PTH 3′-downstream region that was exclusively present in the parathyroid adenoma and our tumor. Such a co-occurrence might act as another driver of ectopic PTH-producing tumorigenesis; both might release the control of PTH gene expression by shutting down the other branches of the safety system (e.g., CaSR and the vitamin D3–vitamin D receptor axis).
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Affiliation(s)
- Kosuke Uchida
- Department of Biochemistry, Teikyo University School of Medicine, Tokyo 173-0003, Japan.,Department of General Practice, National Defense Medical College, Saitama 359-0042, Japan
| | - Yuji Tanaka
- Department of General Practice, National Defense Medical College, Saitama 359-0042, Japan
| | - Hitoshi Ichikawa
- Genetics Division, National Cancer Center Research Institute, Tokyo 104-0045, Japan
| | - Masato Watanabe
- Department of Pathology, Teikyo University School of Medicine, Tokyo 173-0003, Japan
| | - Sachiyo Mitani
- Genetics Division, National Cancer Center Research Institute, Tokyo 104-0045, Japan
| | - Koji Morita
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-0003, Japan
| | - Hiroko Fujii
- Department of Biochemistry, Teikyo University School of Medicine, Tokyo 173-0003, Japan.,Department of Internal Medicine, Self-Defense Forces Central Hospital, Tokyo 154-8532, Japan
| | - Mayumi Ishikawa
- Diabetes and Arteriosclerosis, Nippon Medical School, Musashikosugi Hospital, Kanagawa 211-8533, Japan
| | - Gen Yoshino
- Center for Diabetes, Shinsuma General Hospital, Hyogo 654-0047, Japan
| | - Hiroko Okinaga
- Department of Internal Medicine, Teikyo University School of Medicine, Tokyo 173-0003, Japan
| | - Genta Nagae
- Genome Science Laboratory Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo 153-8904, Japan
| | - Hiroyuki Aburatani
- Genome Science Laboratory Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo 153-8904, Japan
| | - Yoshifumi Ikeda
- Department of Surgery, Teikyo University School of Medicine, Tokyo 173-0003, Japan
| | - Takao Susa
- Department of Biochemistry, Teikyo University School of Medicine, Tokyo 173-0003, Japan
| | - Mimi Tamamori-Adachi
- Department of Biochemistry, Teikyo University School of Medicine, Tokyo 173-0003, Japan
| | - Toshio Fukusato
- Department of Pathology, Teikyo University School of Medicine, Tokyo 173-0003, Japan
| | - Hiroshi Uozaki
- Department of Pathology, Teikyo University School of Medicine, Tokyo 173-0003, Japan
| | - Tomoki Okazaki
- Department of Biochemistry, Teikyo University School of Medicine, Tokyo 173-0003, Japan
| | - Masayoshi Iizuka
- Department of Biochemistry, Teikyo University School of Medicine, Tokyo 173-0003, Japan
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Andrukhova O, Streicher C, Zeitz U, Erben RG. Fgf23 and parathyroid hormone signaling interact in kidney and bone. Mol Cell Endocrinol 2016; 436:224-39. [PMID: 27498418 DOI: 10.1016/j.mce.2016.07.035] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 07/26/2016] [Accepted: 07/26/2016] [Indexed: 12/19/2022]
Abstract
Fibroblast growth factor-23 (FGF23) is a bone-derived hormone, suppressing renal phosphate reabsorption and vitamin D hormone synthesis in proximal tubules, and stimulating calcium reabsorption in distal tubules of the kidney. Here, we analyzed the long term sequelae of deficient Fgf23 signaling on bone and mineral metabolism in 9-month-old mice lacking both Fgf23 or Klotho and a functioning vitamin D receptor (VDR). To prevent hypocalcemia in VDR deficient mice, all mice were kept on a rescue diet enriched with calcium, phosphate, and lactose. VDR mutants were normocalcemic and normophosphatemic, and had normal tibial bone mineral density. Relative to VDR mutants, Fgf23/VDR and Klotho/VDR compound mutants were characterized by hypocalcemia, hyperphosphatemia, and very high serum parathyroid hormone (PTH). Despite ∼10-fold higher serum PTH levels in compound mutants, urinary excretion of phosphate and calcium as well as osteoclast numbers in bone remained unchanged relative to VDR mutants. The increase in plasma cAMP after hPTH(1-34) injection was similar in all genotypes. However, a 5-day infusion of hPTH(1-34) via osmotic minipumps resulted in reduced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) in bone and kidney of Fgf23/VDR and Klotho/VDR compound mutants, relative to VDR and WT controls. Similarly, the PTH-mediated ERK1/2 phosphorylation was reduced in primary osteoblasts isolated from Fgf23 and Klotho deficient mice, but was restored by concomitant treatment with recombinant FGF23. Collectively, our data indicate that the phosphaturic, calcium-conserving, and bone resorption-stimulating actions of PTH are blunted by Fgf23 or Klotho deficiency. Hence, FGF23 may be an important modulator of PTH signaling in bone and kidney.
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Affiliation(s)
- Olena Andrukhova
- Department of Biomedical Sciences, University of Veterinary Medicine, 1210, Vienna, Austria
| | - Carmen Streicher
- Department of Biomedical Sciences, University of Veterinary Medicine, 1210, Vienna, Austria
| | - Ute Zeitz
- Department of Biomedical Sciences, University of Veterinary Medicine, 1210, Vienna, Austria
| | - Reinhold G Erben
- Department of Biomedical Sciences, University of Veterinary Medicine, 1210, Vienna, Austria.
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Shilo V, Ben-Dov IZ, Nechama M, Silver J, Naveh-Many T. Parathyroid-specific deletion of dicer-dependent microRNAs abrogates the response of the parathyroid to acute and chronic hypocalcemia and uremia. FASEB J 2015; 29:3964-76. [PMID: 26054367 DOI: 10.1096/fj.15-274191] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 05/26/2015] [Indexed: 11/11/2022]
Abstract
MicroRNAs (miRNAs) down-regulate gene expression and have vital roles in biology but their functions in the parathyroid are unexplored. To study this, we generated parathyroid-specific Dicer1 knockout (PT-Dicer(-/-) ) mice where parathyroid miRNA maturation is blocked. Remarkably, the PT-Dicer(-/-) mice did not increase serum parathyroid hormone (PTH) in response to acute hypocalcemia compared with the >5-fold increase in controls. PT-Dicer(-/-) glands cultured in low-calcium medium secreted 5-fold less PTH at 1.5 h than controls. Chronic hypocalcemia increased serum PTH >4-fold less in PT-Dicer(-/-) mice compared with control mice with no increase in PTH mRNA levels and parathyroid cell proliferation compared with the 2- to 3-fold increase in hypocalcemic controls. Moreover, uremic PT-Dicer(-/-) mice increased serum PTH and FGF23 significantly less than uremic controls. Therefore, stimulation of the parathyroid by both hypocalcemia and uremia is dependent upon intact dicer function and miRNAs. In contrast, the PT-Dicer(-/-) mice responded normally to activation of the parathyroid calcium-sensing receptor (Casr) by both hypercalcemia and a calcimimetic that decreases PTH secretion, demonstrating that they are dicer-independent. Therefore, miRNAs are essential for the response of the parathyroid to both acute and chronic hypocalcemia and uremia, the major stimuli for PTH secretion.
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Affiliation(s)
- Vitali Shilo
- *Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah Hebrew University Medical Center, Jerusalem, Israel; and Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Iddo Z Ben-Dov
- *Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah Hebrew University Medical Center, Jerusalem, Israel; and Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Morris Nechama
- *Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah Hebrew University Medical Center, Jerusalem, Israel; and Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Justin Silver
- *Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah Hebrew University Medical Center, Jerusalem, Israel; and Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Tally Naveh-Many
- *Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah Hebrew University Medical Center, Jerusalem, Israel; and Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
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Nitta K, Nagano N, Tsuchiya K. Fibroblast growth factor 23/klotho axis in chronic kidney disease. Nephron Clin Pract 2014; 128:1-10. [PMID: 25402964 DOI: 10.1159/000365787] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 06/26/2014] [Indexed: 12/27/2022] Open
Abstract
Fibroblast growth factor-23 (FGF23) is a bone-derived hormone that regulates phosphate and 1,25-hydroxyvitamin D [1,25(OH)2D] metabolism. FGF23 binds to FGF receptor 1 with its coreceptor Klotho and maintains serum phosphate levels within the normal range by increasing renal phosphate excretion. In addition, FGF23 reduces the synthesis and accelerates the degradation of 1,25(OH)2D to reduce intestinal phosphate absorption. Moreover, FGF23 acts at the parathyroid gland to decrease parathyroid hormone synthesis and secretion. In chronic kidney disease (CKD), serum FGF23 levels rise exponentially as renal function declines long before a significant increase in serum phosphate concentration occurs. Although there is room for argument, FGF23 and Klotho are recently reported contributors to vascular calcification. Finally, prospective observational studies have shown that serum FGF23 concentrations predict mortality not only among dialysis patients but among predialysis CKD patients. In addition to being a coreceptor for FGF23, Klotho circulates as an endocrine substance and exerts a multitude of effects. This review describes recent advances in research on the FGF23-Klotho axis in CKD. © 2014 S. Karger AG, Basel.
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Affiliation(s)
- Kosaku Nitta
- Kidney Center, Department of Medicine, Tokyo Women's Medical University, Tokyo, Japan
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Abstract
The regulation of serum phosphate, an acknowledged risk factor for chronic kidney disease and cardiovascular mortality, is poorly understood. The discovery of fibroblast growth factor 23 (FGF23) as a key regulator of renal phosphate handling and activation of vitamin D has revolutionized our comprehension of phosphate homeostasis. Through as yet undetermined mechanisms, circulating and dietary phosphate appear to have a direct effect on FGF23 release by bone cells that, in turn, causes renal phosphate excretion and decreases intestinal phosphate absorption through a decrease in vitamin D production. Thus, the two major phosphaturic hormones, PTH and FGF23, have opposing effects on vitamin D production, placing vitamin D at the nexus of phosphate homeostasis. While our understanding of phosphate homeostasis has advanced, the factors determining regulation of serum phosphate level remain enigmatic. Diet, time of day, season, gender, age and genetics have all been identified as significant contributors to serum phosphate level. The effects of these factors on serum phosphate have major implications for what is understood as 'normal' and for studies of phosphate homeostasis and metabolism. Moreover, other hormonal mediators such as dopamine, insulin-like growth factor, and angiotensin II also affect renal handling of phosphate. How the major hormone effects on phosphate handling are regulated and how the effect of these other factors are integrated to yield the measurable serum phosphate are only now beginning to be studied.
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Affiliation(s)
- Eleanor Lederer
- Medical Services, Robley Rex VA Medical Center, Department of Medicine, University of Louisville School of Medicine, Louisville, KY, 40202, USA
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Silver J, Naveh-Many T. FGF-23 and secondary hyperparathyroidism in chronic kidney disease. Nat Rev Nephrol 2013; 9:641-9. [PMID: 23877588 DOI: 10.1038/nrneph.2013.147] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The metabolic changes that occur in patients with chronic kidney disease (CKD) have a profound influence on mineral and bone metabolism. CKD results in altered levels of serum phosphate, vitamin D, calcium, parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF-23); the increased levels of serum phosphate, PTH and FGF-23 contribute to the increased cardiovascular mortality in affected patients. FGF-23 is produced by osteocytes and osteoblasts and acts physiologically in the kidney to induce phosphaturia and inhibit the synthesis of 1,25-dihydroxyvitamin D3. PTH acts directly on osteocytes to increase FGF-23 expression. In addition, the high levels of PTH associated with CKD contribute to changes in bone remodelling that result in decreased levels of dentin matrix protein 1 and the release of low-molecular-weight fibroblast growth factors from the bone matrix, which stimulate FGF-23 transcription. A prolonged oral phosphorus load increases FGF-23 expression by a mechanism that includes local changes in the ratio of inorganic phosphate to pyrophosphate in bone. Other factors such as dietary vitamin D compounds, calcium, and metabolic acidosis all increase FGF-23 levels. This Review discusses the mechanisms by which secondary hyperparathyroidism associated with CKD stimulates bone cells to overexpress FGF-23 levels.
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Affiliation(s)
- Justin Silver
- Hadassah Hebrew University Medical Center, Minerva Center for Calcium and Bone Metabolism, Nephrology, Ein Karem, Jerusalem 91120, Israel
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Silver J, Naveh-Many T. FGF23 and the parathyroid. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 728:92-9. [PMID: 22396164 DOI: 10.1007/978-1-4614-0887-1_6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Klotho and fibroblast growth factor 1 (FGFR1) are expressed not only in FGF23's classical target organ, the kidney, but also in other organs such as the parathyroid. FGF23 acts on the parathyroid to decrease PTH mRNA and serum PTH levels. It does this by activating the MAPK pathway. In chronic kidney disease there are very high levels of serum FGF23 together with increased serum PTH levels, implying resistance of the parathyroid to the action of FGF23. This has been shown in parathyroid tissue surgically removed from dialysis patients as well as in experimental models of uremia to be due to down-regulation of klotho-FGFR1 expression in the parathyroid. Moreover, the parathyroids of rats with advanced uremia do not respond to administered FGF23 by activation of the MAPK pathway or inhibition of PTH secretion. Therefore, there is down-regulation of parathyroid klotho-FGFR1 in CKD which correlates with the resistance of the parathyroid to FGF23. A further subject of great interest in this field is the effect of PTH to directly increase FGF23 expression by osteoblast like cells in culture and the observations that parathyroidectomy prevents and corrects the increased serum FGF23 level of experimental CKD as well as decreases FGF23 in patients with CKD. There is therefore a negative feedback loop between bone and the parathyroid.
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Affiliation(s)
- Justin Silver
- Hadassah Hebrew University Medical Center, Jerusalem, Israel.
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Bergwitz C, Jüppner H. Phosphate sensing. Adv Chronic Kidney Dis 2011; 18:132-44. [PMID: 21406298 PMCID: PMC3059779 DOI: 10.1053/j.ackd.2011.01.004] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 01/10/2011] [Accepted: 01/17/2011] [Indexed: 02/07/2023]
Abstract
Human phosphate homeostasis is regulated at the level of intestinal absorption of phosphate from the diet, release of phosphate through bone resorption, and renal phosphate excretion, and involves the actions of parathyroid hormone, 1,25-dihydroxy-vitamin D, and fibroblast growth factor 23 to maintain circulating phosphate levels within a narrow normal range, which is essential for numerous cellular functions, for the growth of tissues and for bone mineralization. Prokaryotic and single cellular eukaryotic organisms such as bacteria and yeast "sense" ambient phosphate with a multi-protein complex located in their plasma membrane, which modulates the expression of genes important for phosphate uptake and metabolism (pho pathway). Database searches based on amino acid sequence conservation alone have been unable to identify metazoan orthologs of the bacterial and yeast phosphate sensors. Thus, little is known about how human and other metazoan cells sense inorganic phosphate to regulate the effects of phosphate on cell metabolism ("metabolic" sensing) or to regulate the levels of extracellular phosphate through feedback system(s) ("endocrine" sensing). Whether the "metabolic" and the "endocrine" sensor use the same or different signal transduction cascades is unknown. This article will review the bacterial and yeast phosphate sensors, and then discuss what is currently known about the metabolic and endocrine effects of phosphate in multicellular organisms and human beings.
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Affiliation(s)
- Clemens Bergwitz
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
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Nitta K. Relationship between Fibroblast Growth Factor-23 and Mineral Metabolism in Chronic Kidney Disease. Int J Nephrol 2010; 2010:167984. [PMID: 21234310 PMCID: PMC3018630 DOI: 10.4061/2010/167984] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 10/28/2010] [Indexed: 11/30/2022] Open
Abstract
Fibroblast growth factor- (FGF-)23 is a recently discovered regulator of calcium-phosphate metabolism. FGF-23 appears to decrease in synthesis and accelerated degradation of 1,25(OH)2D. Together with its cofactor Klotho, FGF-23 maintains serum phosphate levels within the normal range by increasing renal phosphate excretion. In chronic kidney disease (CKD), FGF-23 levels rise in parallel with the decline in renal function long before a significant increase in serum phosphate concentration occurs. Both Klotho and FGF-23, linked by a receptor mechanism, affect vitamin D synthesis and parathyroid hormone (PTH) secretion. Previous studies have shown a close association between reduced FGF-23 or Klotho activities and vascular calcification. The possible association of FGF-23 and left ventricular hypertrophy or vascular dysfunction has been proposed. Finally, prospective studies have shown that high serum FGF-23 concentrations predict more rapid disease progression in CKD patients who were not on dialysis and increased mortality in patients on maintenance hemodialysis. FGF-23 may therefore prove to be an important therapeutic target for the management of CKD.
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Affiliation(s)
- Kosaku Nitta
- Department of Medicine, Kidney Center, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
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FGF23 and the parathyroid glands. Pediatr Nephrol 2010; 25:2241-5. [PMID: 20526631 DOI: 10.1007/s00467-010-1565-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 05/04/2010] [Accepted: 05/05/2010] [Indexed: 01/26/2023]
Abstract
Fibroblast growth factor 23 (FGF23) is a phosphatonin that is secreted by osteocytes and osteoblasts in response to hyperphosphatemia and 1,25-dihydroxyvitamin D (1,25D). It acts on its receptor complex, Klotho-FGFR1c (fibroblast growth factor receptor 1 c-splicing form), in the distal convoluted tubule to repress renal phosphorus reabsorption in the proximal tubule and suppress the renal synthesis of 1,25D. Klotho-FGFR1c is also expressed in the parathyroid glands. FGF23 acts on the receptor complex in the parathyroid glands to decrease parathyroid hormone (PTH) gene expression and PTH secretion through activation of the MAPK pathway. In chronic kidney disease (CKD), both FGF23 and PTH are increased, implying resistance of the parathyroid glands to FGF23. There is a decrease in the Klotho-FGFR1c complex in the parathyroid glands in both experimental CKD and in patients with end-stage renal disease. In addition, in advanced experimental CKD, FGF23 has a decreased ability to inhibit PTH expression.
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Manghat P, Fraser WD, Wierzbicki AS, Fogelman I, Goldsmith DJ, Hampson G. Fibroblast growth factor-23 is associated with C-reactive protein, serum phosphate and bone mineral density in chronic kidney disease. Osteoporos Int 2010; 21:1853-61. [PMID: 20012018 DOI: 10.1007/s00198-009-1142-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 11/13/2009] [Indexed: 12/25/2022]
Abstract
UNLABELLED We investigated the association between fibroblast growth factor-23 (FGF-23) and (1) the biochemical parameters implicated in chronic kidney disorder (CKD)-bone and mineral disorder (CKD-MBD) and (2) bone mineral density (BMD) in patients with CKD 1-4. C-reactive protein (CRP) and serum phosphate correlated with FGF-23. A significant association was seen between FGF-23 and BMD at the hip. INTRODUCTION Circulating FGF-23 is elevated in CKD, although the primary stimulus remains unclear. Moreover, it is still unknown whether increase in FGF-23 has a biological effect on bone metabolism. The aim of the study was to investigate the association of FGF-23 with (1) the biochemical parameters linked with CKD-bone and mineral disorder (CKD-MBD) and (2) bone mineral density in CKD. METHODS We studied 145 patients (74 M, 71 F) aged (mean [SD]) 53 [14] years with CKD 1-4. Serum calcium, phosphate, parathyroid hormone, FGF-23, 25 (OH) vitamin D, 1, 25 (OH)(2) vitamin D, bone turnover markers, CRP were determined. BMD was measured at the lumbar spine, femoral neck (FN), forearm, and total hip (TH). Multivariate analysis was undertaken to explore the association between (1) the biochemical variables and FGF-23 and (2) FGF-23 and BMD. RESULTS Elevations in FGF-23 occurred in CKD stage 3 compared to CKD stage 1/2, although no significant differences in serum phosphate were observed. Serum phosphate (p<0.001), CRP (p<0.001) and diabetes mellitus (p<0.05) were associated with FGF-23. BMD Z-score was significantly lower at the TH and FN in CKD 4 (p<0.05). A significant association was seen between BMI, FGF-23, bone specific alkaline phosphatase and BMD at the TH (p<0.05). CONCLUSIONS The data suggest that FGF-23 may be associated with parameters implicated in the complications of CKD. Longitudinal studies are required for further clinical evaluation.
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Affiliation(s)
- P Manghat
- Department of Chemical Pathology, 5th Floor, North Wing, St Thomas' Hospital, Lambeth Palace Road, London, SE1 7EH, UK
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Lavi-Moshayoff V, Wasserman G, Meir T, Silver J, Naveh-Many T. PTH increases FGF23 gene expression and mediates the high-FGF23 levels of experimental kidney failure: a bone parathyroid feedback loop. Am J Physiol Renal Physiol 2010; 299:F882-9. [PMID: 20685823 DOI: 10.1152/ajprenal.00360.2010] [Citation(s) in RCA: 310] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) target the kidney to cause a phosphaturia. FGF23 also acts on the parathyroid to decrease PTH expression, but in chronic kidney disease (CKD) there are high-serum PTH and FGF23 levels and resistance of the parathyroid to FGF23. We now report that PTH acts on bone to increase FGF23 expression and characterize the signal transduction pathway whereby PTH increases FGF23 expression. Remarkably, we show that PTH is necessary for the high-FGF23 levels of early kidney failure due to an adenine high-phosphorus diet. Parathyroidectomy before the diet totally prevented the fivefold increase in FGF23 levels in kidney failure rats. Moreover, parathyroidectomy of early kidney failure rats corrected their high-FGF23 levels. Therefore, in early kidney failure, the high-FGF23 levels are dependent on the high-PTH levels. PTH infusion for 3 days to mice with normal renal function increased serum FGF23 and calvaria FGF23 mRNA levels. To demonstrate a direct effect of PTH on FGF23, we added PTH to rat osteoblast-like UMR106 cells. PTH increased FGF23 mRNA levels (4-fold) and this effect was mimicked by a PKA activator, forskolin. PTH also decreased SOST mRNA levels (3-fold). SOST codes for sclerostin, a Wnt pathway inhibitor, which is a PTH receptor (PTH1R) target. The effect of PTH was prevented by added sclerostin. Therefore, PTH increases FGF23 expression which involves the PKA and Wnt pathways. The effect of PTH on FGF23 completes a bone-parathyroid endocrine feedback loop. Importantly, secondary hyperparathyroidism is essential for the high-FGF23 levels in early CKD.
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Affiliation(s)
- Vardit Lavi-Moshayoff
- Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah Hebrew Univ. Medical Center, PO Box 12000, Jerusalem, Israel 91120
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McAteer ME, Niziolek PJ, Ellis SN, Alge DL, Robling AG. Mechanical stimulation and intermittent parathyroid hormone treatment induce disproportional osteogenic, geometric, and biomechanical effects in growing mouse bone. Calcif Tissue Int 2010; 86:389-96. [PMID: 20306026 PMCID: PMC3412136 DOI: 10.1007/s00223-010-9348-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 02/26/2010] [Indexed: 11/25/2022]
Abstract
Mechanical loading and intermittent parathyroid (iPTH) treatment are both osteoanabolic stimuli and are regulated by partially overlapping cellular signaling pathways. iPTH has been shown clinically to be effective in increasing bone mass and reducing fracture risk. Likewise, mechanical stimulation can significantly enhance bone apposition and prevent bone loss, but its clinical effects on fracture susceptibility are less certain. Many of the osteogenic effects of iPTH are localized to biomechanically suboptimal bone surfaces, whereas mechanical loading directs new bone formation to high-stress areas and not to strain-neutral areas. These differences in localization in new tissue, resulting from load-induced versus iPTH-induced bone accumulation, should affect the relation between bone mass and bone strength, or "tissue economy." We investigated the changes in bone mass and strength induced by 6 weeks of mechanical loading and compared them to changes induced by 6 weeks of iPTH treatment. Loading and iPTH both increased ulnar bone accrual, as measured by bone mineral density and content, and fluorochrome-derived bone formation. iPTH induced a significantly greater increase in bone mass than loading, but ulnar bone strength was increased approximately the same amount by both treatments. Mechanical loading during growth can spatially optimize new bone formation to improve structural integrity with a minimal increase in mass, thereby increasing tissue economy, i.e., the amount of strength returned per unit bone mass added. Furthermore, exercise studies in which only small changes in bone mass are detected might be more beneficial to bone health and fracture resistance than has commonly been presumed.
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Affiliation(s)
- Maureen E. McAteer
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Paul J. Niziolek
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Shana N. Ellis
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Daniel L. Alge
- Department of Biomedical Engineering, Indiana University–Purdue University at Indianapolis, Indianapolis, IN, USA
| | - Alexander G. Robling
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Biomedical Engineering, Indiana University–Purdue University at Indianapolis, Indianapolis, IN, USA
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