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Xiao L, Clarke K, Hurley MM. Fibroblast Growth Factor 23 Neutralizing Antibody Ameliorates Abnormal Renal Phosphate Handling in Sickle Cell Disease Mice. Endocrinology 2023; 164:bqad173. [PMID: 37972265 PMCID: PMC11032245 DOI: 10.1210/endocr/bqad173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023]
Abstract
We assessed the involvement of fibroblast growth factor 23 (FGF23) in phosphaturia in sickle cell disease (SCD) mice. Control and SCD mice were treated with FGF23 neutralizing antibody (FGF23Ab) for 24 hours. Serum ferritin was significantly increased in SCD mice and was significantly reduced in female but not male SCD mice by FGF23Ab. FGF23Ab significantly reduced increased erythropoietin in SCD kidneys. Serum intact FGF23 was significantly increased in SCD female mice and was markedly increased in SCD male mice; however, FGF23Ab significantly reduced serum intact FGF23 in both genotypes and sexes. Serum carboxy-terminal-fragment FGF23 (cFGF23) was significantly reduced in SCD IgG male mice and was markedly but not significantly reduced in SCD IgG female mice. FGF23Ab significantly increased cFGF23 in both sexes and genotypes. Serum 1,25-dihydroxyvitamin D3 was significantly increased in SCD IgG and was further significantly increased by FGF23Ab in both sexes and genotypes. Significantly increased blood urea nitrogen in SCD was not reduced by FGF23Ab. The urine phosphate (Pi)/creatinine ratio was significantly increased in SCD in both sexes and was significantly reduced by FGF23Ab. Increased SCD kidney damage marker kidney injury molecule 1 was rescued, but sclerotic glomeruli, increased macrophages, and lymphocytes were not rescued by short-term FGF23Ab. FGF23Ab significantly reduced increased phospho-fibroblast growth factor receptor 1, αKlotho, phosphorylated extracellular signal-regulated kinase, phosphorylated serum/glucocorticoid-regulated kinase 1, phosphorylated sodium-hydrogen exchanger regulatory factor-1, phosphorylated janus kinase 3, and phosphorylated transducer and activator of transcription-3 in SCD kidneys. The type II sodium Pi cotransporter (NPT2a) and sodium-dependent Pi transporter PiT-2 proteins were significantly reduced in SCD kidneys and were increased by FGF23Ab. We conclude that increased FGF23/FGF receptor 1/αKlotho signaling promotes Pi wasting in SCD by downregulating NPT2a and PIT2 via modulation of multiple signaling pathways that could be rescued by FGF23Ab.
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Affiliation(s)
- Liping Xiao
- Department of Medicine, Division of Endocrinology and Metabolism, UConn Health School of Medicine, Farmington, CT, 06030, USA
| | - Kai Clarke
- Department of Medicine, Division of Endocrinology and Metabolism, UConn Health School of Medicine, Farmington, CT, 06030, USA
| | - Marja M Hurley
- Department of Medicine, Division of Endocrinology and Metabolism, UConn Health School of Medicine, Farmington, CT, 06030, USA
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Cernaro V, Longhitano E, Calabrese V, Casuscelli C, Di Carlo S, Spinella C, Gembillo G, Santoro D. Progress in pharmacotherapy for the treatment of hyperphosphatemia in renal failure. Expert Opin Pharmacother 2023; 24:1737-1746. [PMID: 37527180 DOI: 10.1080/14656566.2023.2243817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 07/26/2023] [Accepted: 07/31/2023] [Indexed: 08/03/2023]
Abstract
INTRODUCTION Among the clinical and metabolic complications of progressive chronic kidney disease (CKD), CKD-mineral bone disorder (CKD-MBD) significantly contributes to morbidity and mortality. While overt and persistent hyperphosphatemia is typical of advanced CKD and requires treatment, other abnormalities of calcium/phosphate metabolism begin to occur since the early stages of the disease. AREAS COVERED We searched on the PubMed database, without restrictions for language or time range, for randomized clinical trials and meta-analyses investigating phosphate-lowering therapies. The various phosphate binders show different safety profiles and diverse effects on calcium/phosphate metabolism and vascular calcification. The in-depth knowledge of the characteristics of these drugs is crucial to ensure adequate treatment to CKD patients. EXPERT OPINION A proper control of serum phosphate can be achieved using phosphate binders. These medications may induce side effects. Moreover, data on their impact on clinical outcomes are partly controversial or scarce, especially for the new generation drugs. Hyperphosphatemia favors cardiovascular disease and increases the risk for CKD progression. These effects are partially mediated by fibroblast growth factor 23 (FGF23), a phosphaturic hormone that raises to maintain normal serum phosphate. Since there are no data supporting the use of phosphate-lowering agents when phosphataemia is normal, a key role is played by reducing dietary phosphate intake with the aim to control serum phosphate and the compensatory FGF23 and parathyroid hormone (PTH) increase.
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Affiliation(s)
- Valeria Cernaro
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Elisa Longhitano
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Vincenzo Calabrese
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Chiara Casuscelli
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Silvia Di Carlo
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Claudia Spinella
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Guido Gembillo
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Domenico Santoro
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
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3
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Gehring N, Bettoni C, Wagner CA, Rubio-Aliaga I. Jak1/Stat3 Activation Alters Phosphate Metabolism Independently of Sex and Extracellular Phosphate Levels. Kidney Blood Press Res 2021; 46:714-722. [PMID: 34515136 DOI: 10.1159/000518488] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/12/2021] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Phosphate homeostasis is regulated by a complex network involving the parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and calcitriol acting on several organs including the kidney, intestine, bone, and parathyroid gland. Previously, we showed that activation of the Janus kinase 1 (Jak1)-signal transducer and activator of transcription 3 (Stat3) signaling pathway leads to altered mineral metabolism with higher FGF23 levels, lower PTH, and higher calcitriol levels. Here, we investigated if there are sex differences in the role of Jak1/Stat3 signaling pathway on phosphate metabolism and if this pathway is sensitive to extracellular phosphate alterations. METHODS We used a mouse model (Jak1S645P+/-) that resembles a constitutive activating mutation of the Jak1/Stat3 signaling pathway in humans and analyzed the impact of sex on mineral metabolism parameters. Furthermore, we challenged Jak1S645P+/- male and female mice with a high (1.2% w/w) and low (0.1% w/w) phosphate diet and a diet with phosphate with organic origin with lower bioavailability. RESULTS Female mice, as male mice, showed higher intact FGF23 levels but no phosphaturia, and higher calcitriol and lower PTH levels in plasma. A phosphate challenge did not alter the effect of Jak1/Stat3 activation on phosphate metabolism for both genders. However, under a low phosphate diet or a diet with lower phosphate availability, the animals showed a tendency to develop hypophosphatemia. Moreover, male and female mice showed similar phosphate metabolism parameters. The only exception was higher PTH levels in male mice than those in females. DISCUSSION/CONCLUSION Sex and extracellular phosphate levels do not affect the impact of Jak1/Stat3 activation on phosphate metabolism.
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Affiliation(s)
- Nicole Gehring
- Institute of Physiology, University of Zurich, National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Carla Bettoni
- Institute of Physiology, University of Zurich, National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zurich, National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
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4
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Fuente R, Gehring N, Bettoni C, Gil-Peña H, Alonso-Durán L, Michalke B, Santos F, Wagner CA, Rubio-Aliaga I. Systemic Jak1 activation causes extrarenal calcitriol production and skeletal alterations provoking stunted growth. FASEB J 2021; 35:e21721. [PMID: 34118090 DOI: 10.1096/fj.202100587r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/12/2021] [Accepted: 05/20/2021] [Indexed: 02/06/2023]
Abstract
Mineral homeostasis is regulated by a complex network involving endocrine actions by calcitriol, parathyroid hormone (PTH), and FGF23 on several organs including kidney, intestine, and bone. Alterations of mineral homeostasis are found in chronic kidney disease and other systemic disorders. The interplay between the immune system and the skeletal system is not fully understood, but cytokines play a major role in modulating calcitriol production and function. One of the main cellular signaling pathways mediating cytokine function is the Janus kinase (JAK)--signal transducer and activator of transcription (STAT) pathway. Here, we used a mouse model (Jak1S645P+/- ) that resembles a constitutive activating mutation of the Jak1/Stat3 signaling pathway in humans, and shows altered mineral metabolism, with higher fibroblast growth factor 23 (FGF23) levels, lower PTH levels, and higher calcitriol levels. The higher calcitriol levels are probably due to extrarenal calcitriol production. Furthermore, systemic Jak1/Stat3 activation led to growth impairment and skeletal alterations. The growth plate in long bones showed decreased chondrocyte proliferation rates and reduced height of terminal chondrocytes. Furthermore, we demonstrate that Jak1 is also involved in bone remodeling early in life. Jak1S645P+/- animals have decreased bone and cortical volume, imbalanced bone remodeling, reduced MAP kinase signaling, and local inflammation. In conclusion, Jak1 plays a major role in bone health probably both, directly and systemically by regulating mineral homeostasis. Understanding the role of this signaling pathway will contribute to a better knowledge in bone growth and in mineral physiology, and to the development of selective Jak inhibitors as osteoprotective agents.
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Affiliation(s)
- Rocío Fuente
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.,Division of Pediatrics, University of Oviedo, Oviedo, Spain
| | - Nicole Gehring
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Carla Bettoni
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | | | | | - Bernhard Michalke
- Department of Environmental Science, Research Unit Analytical, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Fernando Santos
- Division of Pediatrics, University of Oviedo, Oviedo, Spain.,Department of Pediatrics, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
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5
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Daryadel A, Ruiz PA, Gehring N, Stojanovic D, Ugrica M, Bettoni C, Sabrautzki S, Pastor‐Arroyo E, Frey‐Wagner I, Lorenz‐Depiereux B, Strom TM, Angelis MH, Rogler G, Wagner CA, Rubio‐Aliaga I. Systemic Jak1 activation provokes hepatic inflammation and imbalanced FGF23 production and cleavage. FASEB J 2021; 35:e21302. [DOI: 10.1096/fj.202002113r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 12/24/2022]
Affiliation(s)
- Arezoo Daryadel
- Institute of Physiology University of Zurich (UZH), and National Center of Competence in Research NCCR Kidney.CH Zurich Switzerland
| | - Pedro A. Ruiz
- Department of Gastroenterology and Hepatology University Hospital of Zurich, University of Zurich Zurich Switzerland
| | - Nicole Gehring
- Institute of Physiology University of Zurich (UZH), and National Center of Competence in Research NCCR Kidney.CH Zurich Switzerland
| | - Dragana Stojanovic
- Institute of Physiology University of Zurich (UZH), and National Center of Competence in Research NCCR Kidney.CH Zurich Switzerland
| | - Marko Ugrica
- Institute of Physiology University of Zurich (UZH), and National Center of Competence in Research NCCR Kidney.CH Zurich Switzerland
| | - Carla Bettoni
- Institute of Physiology University of Zurich (UZH), and National Center of Competence in Research NCCR Kidney.CH Zurich Switzerland
| | - Sibylle Sabrautzki
- Institute of Experimental Genetics German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH) Neuherberg85764Germany
| | - Eva‐Maria Pastor‐Arroyo
- Institute of Physiology University of Zurich (UZH), and National Center of Competence in Research NCCR Kidney.CH Zurich Switzerland
| | - Isabelle Frey‐Wagner
- Department of Gastroenterology and Hepatology University Hospital of Zurich, University of Zurich Zurich Switzerland
| | - Bettina Lorenz‐Depiereux
- Institute of Human Genetics, Helmholtz Zentrum München German Research Center for Environmental Health (GmbH) Neuherberg Germany
| | - Tim M. Strom
- Institut für Humangenetik Klinikum rechts der Isar der Technischen Universität München München Germany
| | - Martin Hrabě Angelis
- Institute of Experimental Genetics German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH) Neuherberg85764Germany
- Lehrstuhl für Experimentelle Genetik Technische Universität München Freising‐Weihenstephan Germany
- Member of German Center for Diabetes Research (DZD) Neuherberg Germany
| | - Gerhard Rogler
- Department of Gastroenterology and Hepatology University Hospital of Zurich, University of Zurich Zurich Switzerland
| | - Carsten A. Wagner
- Institute of Physiology University of Zurich (UZH), and National Center of Competence in Research NCCR Kidney.CH Zurich Switzerland
| | - Isabel Rubio‐Aliaga
- Institute of Physiology University of Zurich (UZH), and National Center of Competence in Research NCCR Kidney.CH Zurich Switzerland
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Li Y, Liu Y, Huang Y, Yang K, Xiao T, Xiong J, Wang K, Liu C, He T, Yu Y, Han W, Wang Y, Bi X, Zhang J, Huang Y, Zhang B, Zhao J. IRF-1 promotes renal fibrosis by downregulation of Klotho. FASEB J 2020; 34:4415-4429. [PMID: 31965641 DOI: 10.1096/fj.201902446r] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/29/2019] [Accepted: 01/13/2020] [Indexed: 01/06/2023]
Abstract
Although the key role of renal fibrosis in the progression of chronic kidney disease (CKD) is well known, the causes of renal fibrosis are not fully clarified. In this study, interferon regulatory factor 1 (IRF-1), a mammalian transcription factor, was highly expressed in fibrotic kidney of CKD patients. Concordantly, the expression level of IRF-1 was significantly elevated in the kidney of unilateral ureteral obstruction (UUO) and Adriamycin nephropathy (ADR) mice. In tubular epithelial cells, overexpression of IRF-1 could induce profibrotic markers expression, which accompanied by dramatic downregulation of Klotho, an important inhibitor of renal fibrosis. Luciferase reporter analysis and ChIP assay revealed that IRF-1 repressed Klotho expression by downregulation of C/EBP-β, which regulates Klotho gene transcription via directly binding to its promoter. Further investigation showed that tumor necrosis factor-alpha may be an important inducement for the increase of IRF-1 in tubular epithelial cells after UUO and genetic deletion of IRF-1 attenuated renal fibrosis in UUO mice. Hence, these findings demonstrate that IRF-1 contributes to the pathogenesis of renal fibrosis by downregulation of Klotho, and suppresses IRF-1 may be a potential therapeutic target for CKD.
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Affiliation(s)
- Yan Li
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Yong Liu
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Yinghui Huang
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Ke Yang
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Tangli Xiao
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Jiachuan Xiong
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Kailong Wang
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Chi Liu
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Ting He
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Yanlin Yu
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Wenhao Han
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Yue Wang
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Xianjin Bi
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Jingbo Zhang
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Yunjian Huang
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Bo Zhang
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Jinghong Zhao
- Department of Nephrology, The Key Laboratory for the Prevention and Treatment of Chronic Kidney Disease of Chongqing, Kidney Center of PLA, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
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7
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Erben RG, Andrukhova O. FGF23-Klotho signaling axis in the kidney. Bone 2017; 100:62-68. [PMID: 27622885 DOI: 10.1016/j.bone.2016.09.010] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Revised: 09/08/2016] [Accepted: 09/09/2016] [Indexed: 01/04/2023]
Abstract
Fibroblast growth factor-23 (FGF23) is a bone-derived hormone protecting against the potentially deleterious effects of hyperphosphatemia by suppression of phosphate reabsorption and of active vitamin D hormone synthesis in the kidney. The kidney is one of the main target organs of FGF23 signaling. The purpose of this review is to highlight the recent advances in the area of FGF23-Klotho signaling in the kidney. During recent years, it has become clear that FGF23 acts independently on proximal and distal tubular epithelium. In proximal renal tubules, FGF23 suppresses phosphate reabsorption by a Klotho dependent activation of extracellular signal-regulated kinase-1/2 (ERK1/2) and of serum/glucocorticoid-regulated kinase-1 (SGK1), leading to phosphorylation of the scaffolding protein Na+/H+ exchange regulatory cofactor (NHERF)-1 and subsequent internalization and degradation of sodium-phosphate cotransporters. In distal renal tubules, FGF23 augments calcium and sodium reabsorption by increasing the apical membrane expression of the epithelial calcium channel TRPV5 and of the sodium-chloride cotransporter NCC through a Klotho dependent activation of with-no-lysine kinase-4 (WNK4). In proximal and distal renal tubules, FGF receptor-1 is probably the dominant FGF receptor mediating the effects of FGF23 by forming a complex with membrane-bound Klotho in the basolateral membrane. The newly described sodium- and calcium-conserving functions of FGF23 may have major implications for the pathophysiology of diseases characterized by chronically increased circulating FGF23 concentrations such as chronic kidney disease.
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8
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Abstract
Fibroblast growth factor-23 (FGF23) is a bone-derived hormone known to suppress phosphate reabsorption and vitamin D hormone production in the kidney. Klotho was originally discovered as an anti-aging factor, but the functional role of Klotho is still a controversial issue. Three major functions have been proposed, a hormonal function of soluble Klotho, an enzymatic function as glycosidase, and the function as an obligatory co-receptor for FGF23 signaling. The purpose of this review is to highlight the recent advances in the area of FGF23 and Klotho signaling in the kidney, in the parathyroid gland, in the cardiovascular system, in bone, and in the central nervous system. During recent years, major new functions of FGF23 and Klotho have been discovered in these organ systems. Based on these novel findings, FGF23 has emerged as a pleiotropic endocrine and auto-/paracrine factor influencing not only mineral metabolism but also cardiovascular function.
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9
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Abstract
PURPOSE OF REVIEW Fibroblast growth factor-23 (FGF23) is a bone-derived hormone known to suppress phosphate reabsorption in the kidney. The purpose of this review was to highlight the recent advances in the area of FGF23-regulated solute transport in the kidney. RECENT FINDINGS Recent evidence suggests that FGF23 suppresses phosphate reabsorption in renal proximal tubular epithelium by a Klotho-dependent, FGF receptor (FGFR)-1 and FGFR4-mediated signaling mechanism that may also involve Janus kinase 3. Moreover, it was recently established that FGF23 signaling in the distal renal tubule targets with-no-lysine kinase-4 (WNK4), a key molecule in the regulation of solute transport in the distal nephron. By targeting WNK4, FGF23 has been shown to increase the membrane abundance of the epithelial calcium channel TRPV5 and of the sodium-chloride cotransporter NCC, resulting in augmented renal calcium and sodium reabsorption. SUMMARY Significant progress has been made in the further characterization of the signaling pathways involved in the FGF23-induced inhibition of phosphate transport in proximal tubular epithelium, and major new functions of FGF23 in solute transport have been discovered in distal renal tubules. The calcium- and sodium-conserving functions of FGF23 may have major implications for the pathophysiology of cardiovascular diseases. VIDEO ABSTRACT.
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10
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Sakai N, Wada T. T Helper 2 Cytokine Signaling in Bone Marrow-Derived Fibroblasts: A Target for Renal Fibrosis. J Am Soc Nephrol 2015; 26:2896-8. [PMID: 26032812 DOI: 10.1681/asn.2015040469] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- Norihiko Sakai
- Divisions of Blood Purification and Nephrology, Kanazawa University Hospital, Kanazawa, Japan; and
| | - Takashi Wada
- Nephrology, Kanazawa University Hospital, Kanazawa, Japan; and Department of Laboratory Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Faculty of Medicine, Kanazawa University, Kanazawa, Japan
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11
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White JH. JAK3 talks down to renal 25-hydroxyvitamin D 1α-hydroxylase. Kidney Int 2015; 87:678-9. [PMID: 25826541 DOI: 10.1038/ki.2014.380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
25-Hydroxyvitamin D 1α-hydroxylase CYP27B1 is expressed in several extrarenal tissues. In the immune system, and likely elsewhere, its expression is not regulated by calcium and phosphate homeostatic inputs. Umbach et al. provide evidence that inflammatory cytokine signaling may also control CYP27B1 expression in renal epithelia. Mice lacking JAK3, a kinase essential for immune homeostasis, displayed mild renal inflammation, elevated renal CYP27B1 expression, and altered phosphate metabolism, linking immune signaling to vitamin D metabolism in the kidney.
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Affiliation(s)
- John H White
- 1] Department of Physiology, McGill University, Montreal, Quebec, Canada [2] Department of Medicine, McGill University, Montreal, Quebec, Canada
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12
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Checkpoint kinase Chk2 controls renal Cyp27b1 expression, calcitriol formation, and calcium-phosphate metabolism. Pflugers Arch 2014; 467:1871-80. [PMID: 25319519 DOI: 10.1007/s00424-014-1625-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/29/2014] [Accepted: 10/01/2014] [Indexed: 02/08/2023]
Abstract
Checkpoint kinase 2 (Chk2) is the main effector kinase of ataxia telangiectasia mutated (ATM) and responsible for cell cycle regulation. ATM signaling has been shown to upregulate interferon-regulating factor-1 (IRF-1), a transcription factor also expressed in the kidney. Calcitriol (1,25 (OH)2D3), a major regulator of mineral metabolism, is generated by 25-hydroxyvitamin D 1α-hydroxylase in the kidney. Since 25-hydroxyvitamin D 1α-hydroxylase expression is enhanced by IRF-1, the present study explored the role of Chk2 for calcitriol formation and mineral metabolism. Chk2-deficient mice (chk2 (-/-)) were compared to wild-type mice (chk2 (+/+)). Transcript levels of renal 25-hydroxyvitamin D 1α-hydroxylase, Chk2, and IRF-1 were determined by RT-PCR; Klotho expression by Western blotting; bone density by μCT analysis; serum or plasma 1,25 (OH)2D3, PTH, and C-terminal FGF23 concentrations by immunoassays; and serum, fecal, and urinary calcium and phosphate concentrations by photometry. The renal expression of IRF-1 and 25-hydroxyvitamin D 1α-hydroxylase as well as serum 1,25 (OH)2D3 and FGF23 levels were significantly lower in chk2 (-/-) mice compared to chk2 (+/+) mice. Plasma PTH was not different between the genotypes. Renal calcium and phosphate excretion were significantly higher in chk2 (-/-) mice than in chk2 (+/+) mice despite hypophosphatemia and normocalcemia. Bone density was not different between the genotypes. We conclude that Chk2 regulates renal 25-hydroxyvitamin D 1α-hydroxylase expression thereby impacting on calcium and phosphate metabolism.
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