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Jung HJ, Pham TD, Su XT, Grigore TV, Hoenderop JG, Olauson H, Wall SM, Ellison DH, Welling PA, Al-Qusairi L. Klotho is highly expressed in the chief sites of regulated potassium secretion, and it is stimulated by potassium intake. Sci Rep 2024; 14:10740. [PMID: 38729987 PMCID: PMC11087591 DOI: 10.1038/s41598-024-61481-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 05/06/2024] [Indexed: 05/12/2024] Open
Abstract
Klotho regulates many pathways in the aging process, but it remains unclear how it is physiologically regulated. Because Klotho is synthesized, cleaved, and released from the kidney; activates the chief urinary K+ secretion channel (ROMK) and stimulates urinary K+ secretion, we explored if Klotho protein is regulated by dietary K+ and the potassium-regulatory hormone, Aldosterone. Klotho protein along the nephron was evaluated in humans and in wild-type (WT) mice; and in mice lacking components of Aldosterone signaling, including the Aldosterone-Synthase KO (AS-KO) and the Mineralocorticoid-Receptor KO (MR-KO) mice. We found the specific cells of the distal nephron in humans and mice that are chief sites of regulated K+ secretion have the highest Klotho protein expression along the nephron. WT mice fed K+-rich diets increased Klotho expression in these cells. AS-KO mice exhibit normal Klotho under basal conditions but could not upregulate Klotho in response to high-K+ intake in the K+-secreting cells. Similarly, MR-KO mice exhibit decreased Klotho protein expression. Together, i) Klotho is highly expressed in the key sites of regulated K+ secretion in humans and mice, ii) In mice, K+-rich diets increase Klotho expression specifically in the potassium secretory cells of the distal nephron, iii) Aldosterone signaling is required for Klotho response to high K+ intake.
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Affiliation(s)
- Hyun Jun Jung
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Truyen D Pham
- Department of Nephrology, Emory University School of Medicine, Atlanta, GA, USA
| | - Xiao-Tong Su
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, USA
| | - Teodora Veronica Grigore
- Department of Medical BioSciences, Radboud Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G Hoenderop
- Department of Medical BioSciences, Radboud Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hannes Olauson
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Susan M Wall
- Department of Nephrology, Emory University School of Medicine, Atlanta, GA, USA
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, USA
| | - Paul A Welling
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lama Al-Qusairi
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Daryadel A, Tang C, Xie Y, Peitzsch M, Fisi V, Hantel C, Loffing-Cueni D, Breault DT, Penton D, Loffing J, Beuschlein F. Zona Glomerulosa-Derived Klotho Modulates Aldosterone Synthase Expression in Young Female Mice. Endocrinology 2024; 165:bqae040. [PMID: 38573585 PMCID: PMC11002783 DOI: 10.1210/endocr/bqae040] [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: 12/14/2023] [Revised: 03/12/2024] [Accepted: 03/22/2024] [Indexed: 04/05/2024]
Abstract
Klotho plays a critical role in the regulation of ion and fluid homeostasis. A previous study reported that haplo-insufficiency of Klotho in mice results in increased aldosterone synthase (CYP11B2) expression, elevated plasma aldosterone, and high blood pressure. This phenotype was presumed to be the result of diminished Klotho expression in zona glomerulosa (zG) cells of the adrenal cortex; however, systemic effects on adrenal aldosterone production could not be ruled out. To examine whether Klotho expressed in the zG is indeed a critical regulator of aldosterone synthesis, we generated a tamoxifen-inducible, zG-specific mouse model of Klotho deficiency by crossing Klotho-flox mice with Cyp11b2-CreERT mice (zG-Kl-KO). Tamoxifen-treated Cyp11b2-CreERT animals (zG-Cre) served as controls. Rosa26-mTmG reporter mice were used for Cre-dependent lineage-marking. Two weeks after tamoxifen induction, the specificity of the zG-Cre line was verified using immunofluorescence analysis to show that GFP expression was restricted to the zG. RNA in situ hybridization revealed a 65% downregulation of Klotho messenger RNA expression in the zG of zG-Kl-KO female mice at age 12 weeks compared to control mice. Despite this significant decrease, zG-Kl-KO mice exhibited no difference in plasma aldosterone levels. However, adrenal CYP11B2 expression and the CYP11B2 promotor regulatory transcription factors, NGFIB and Nurr1, were enhanced. Together with in vitro experiments, these results suggest that zG-derived Klotho modulates Cyp11b2 but does not evoke a systemic phenotype in young adult mice on a normal diet. Further studies are required to investigate the role of adrenal Klotho on aldosterone synthesis in aged animals.
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Affiliation(s)
- Arezoo Daryadel
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Zürich (USZ) and University of Zürich (UZH), 8091 Zurich, Switzerland
| | - Cong Tang
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Zürich (USZ) and University of Zürich (UZH), 8091 Zurich, Switzerland
| | - Ye Xie
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Zürich (USZ) and University of Zürich (UZH), 8091 Zurich, Switzerland
| | - Mirko Peitzsch
- Institute of Clinical Chemistry and Laboratory Medicine, University Hospital and Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Viktoria Fisi
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Zürich (USZ) and University of Zürich (UZH), 8091 Zurich, Switzerland
| | - Constanze Hantel
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Zürich (USZ) and University of Zürich (UZH), 8091 Zurich, Switzerland
| | | | - David T Breault
- Division of Endocrinology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - David Penton
- Electrophysiology Facility, University of Zurich, 8057 Zürich, Switzerland
| | - Johannes Loffing
- Institute of Anatomy, University of Zürich, 8057 Zurich, Switzerland
| | - Felix Beuschlein
- Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital of Zürich (USZ) and University of Zürich (UZH), 8091 Zurich, Switzerland
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, Ludwig-Maximilians-Universität, 81377 Munich, Germany
- The LOOP Zurich Medical Research Center, 8044 Zurich, Switzerland
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3
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Radvanyi Z, Yoo EJ, Kandasamy P, Salas-Bastos A, Monnerat S, Refardt J, Christ-Crain M, Hayashi H, Kondo Y, Jantsch J, Rubio-Aliaga I, Sommer L, Wagner CA, Hediger MA, Kwon HM, Loffing J, Pathare G. Extracellular sodium regulates fibroblast growth factor 23 (FGF23) formation. J Biol Chem 2024; 300:105480. [PMID: 37992803 PMCID: PMC10770535 DOI: 10.1016/j.jbc.2023.105480] [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: 07/04/2023] [Revised: 10/30/2023] [Accepted: 11/16/2023] [Indexed: 11/24/2023] Open
Abstract
The bone-derived hormone fibroblast growth factor-23 (FGF23) has recently received much attention due to its association with chronic kidney disease and cardiovascular disease progression. Extracellular sodium concentration ([Na+]) plays a significant role in bone metabolism. Hyponatremia (lower serum [Na+]) has recently been shown to be independently associated with FGF23 levels in patients with chronic systolic heart failure. However, nothing is known about the direct impact of [Na+] on FGF23 production. Here, we show that an elevated [Na+] (+20 mM) suppressed FGF23 formation, whereas low [Na+] (-20 mM) increased FGF23 synthesis in the osteoblast-like cell lines UMR-106 and MC3T3-E1. Similar bidirectional changes in FGF23 abundance were observed when osmolality was altered by mannitol but not by urea, suggesting a role of tonicity in FGF23 formation. Moreover, these changes in FGF23 were inversely proportional to the expression of NFAT5 (nuclear factor of activated T cells-5), a transcription factor responsible for tonicity-mediated cellular adaptations. Furthermore, arginine vasopressin, which is often responsible for hyponatremia, did not affect FGF23 production. Next, we performed a comprehensive and unbiased RNA-seq analysis of UMR-106 cells exposed to low versus high [Na+], which revealed several novel genes involved in cellular adaptation to altered tonicity. Additional analysis of cells with Crisp-Cas9-mediated NFAT5 deletion indicated that NFAT5 controls numerous genes associated with FGF23 synthesis, thereby confirming its role in [Na+]-mediated FGF23 regulation. In line with these in vitro observations, we found that hyponatremia patients have higher FGF23 levels. Our results suggest that [Na+] is a critical regulator of FGF23 synthesis.
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Affiliation(s)
- Zsuzsa Radvanyi
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; Swiss National Centre of Competence in Research "Kidney Control of Homeostasis", Zurich, Switzerland
| | - Eun Jin Yoo
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Palanivel Kandasamy
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Bern, Switzerland
| | | | - Sophie Monnerat
- Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland; Department of Clinical Research, University of Basel, Basel, Switzerland
| | - Julie Refardt
- Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland; Department of Clinical Research, University of Basel, Basel, Switzerland
| | - Mirjam Christ-Crain
- Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland; Department of Clinical Research, University of Basel, Basel, Switzerland
| | - Himeka Hayashi
- Department of Animal Sciences, Teikyo University of Science, Yamanashi, Japan
| | - Yasuhiko Kondo
- Department of Animal Sciences, Teikyo University of Science, Yamanashi, Japan
| | - Jonathan Jantsch
- Institute of Clinical Microbiology and Hygiene, University Hospital of Regensburg and University of Regensburg, Regensburg, Germany; Institute for Medical Microbiology, Immunology, and Hygiene, and Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Isabel Rubio-Aliaga
- Swiss National Centre of Competence in Research "Kidney Control of Homeostasis", Zurich, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Lukas Sommer
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Carsten A Wagner
- Swiss National Centre of Competence in Research "Kidney Control of Homeostasis", Zurich, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Matthias A Hediger
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Bern, Switzerland
| | - Hyug Moo Kwon
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Johannes Loffing
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; Swiss National Centre of Competence in Research "Kidney Control of Homeostasis", Zurich, Switzerland
| | - Ganesh Pathare
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; Swiss National Centre of Competence in Research "Kidney Control of Homeostasis", Zurich, Switzerland.
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Kanbay M, Copur S, Tanriover C, Yavuz F, Galassi A, Ciceri P, Cozzolino M. The pathophysiology and management of vascular calcification in chronic kidney disease patients. Expert Rev Cardiovasc Ther 2023; 21:75-85. [PMID: 36716079 DOI: 10.1080/14779072.2023.2174525] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
INTRODUCTION Vascular calcification (VC) which is the pathological mineral deposition in the vascular system, predominantly at the intimal and medial layer of the vessel wall, is an important comorbidity in patients with chronic kidney disease (CKD) leading to significant morbidity and mortality while necessitating appropriate treatment. Our review aims to provide an in-depth analysis of the current understanding of VC. AREAS COVERED In this review, we first discuss the pathophysiology of VC in CKD patients, then we explain the methods to predict and assess VC. Afterwards, we provide the currently available as well as the potential therapeutic approaches of VC. We finally discuss our understanding regarding the current situation surrounding VC in our expert opinion section. EXPERT OPINION Predicting, assessing and treating VC is crucial and the future advances in the field of research surrounding VC will potentially occur in one or more of these three areas of clinical management. There is a current lack of evidence and consensus regarding specific therapeutic options for alleviating VC and this situation may not necessitate VC to be determined, detected, and documented before the available options are implemented. Regardless, the prediction and assessment of VC is still important and requires further improvement together with the developments in therapeutic alternatives. The future has the potential to bring better research which would guide and improve the management of this patient group. A more specialized approach consisting of targeted therapies and more tailored management plans for patients with CKD and VC is on the horizon.
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Affiliation(s)
- Mehmet Kanbay
- Department of Medicine, Division of Nephrology, Koc University School of Medicine, Istanbul, Turkey.,Department of Health Sciences, Renal Division, University of Milan, ASST Santi Paolo e Carlo, 20142 Milan, Italy
| | - Sidar Copur
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Cem Tanriover
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Furkan Yavuz
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Andrea Galassi
- Department of Health Sciences, Renal Division, University of Milan, ASST Santi Paolo e Carlo, 20142 Milan, Italy
| | - Paola Ciceri
- Department of Health Sciences, Renal Division, University of Milan, ASST Santi Paolo e Carlo, 20142 Milan, Italy
| | - Mario Cozzolino
- Department of Health Sciences, Renal Division, University of Milan, ASST Santi Paolo e Carlo, 20142 Milan, Italy
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The regulation of FGF23 under physiological and pathophysiological conditions. Pflugers Arch 2022; 474:281-292. [PMID: 35084563 PMCID: PMC8837506 DOI: 10.1007/s00424-022-02668-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 12/18/2022]
Abstract
Fibroblast growth factor 23 (FGF23) is an important bone hormone that regulates phosphate homeostasis in the kidney along with active vitamin D (1,25(OH)2D3) and parathyroid hormone (PTH). Endocrine effects of FGF23 depend, at least in part, on αKlotho functioning as a co-receptor whereas further paracrine effects in other tissues are αKlotho-independent. Regulation of FGF23 production is complex under both, physiological and pathophysiological conditions. Physiological regulators of FGF23 include, but are not limited to, 1,25(OH)2D3, PTH, dietary phosphorus intake, and further intracellular and extracellular factors, kinases, cytokines, and hormones. Moreover, several acute and chronic diseases including chronic kidney disease (CKD) or further cardiovascular disorders are characterized by early rises in the plasma FGF23 level pointing to further mechanisms effective in the regulation of FGF23 under pathophysiological conditions. Therefore, FGF23 also serves as a prognostic marker in several diseases. Our review aims to comprehensively summarize the regulation of FGF23 in health and disease.
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Tsilosani A, Gao C, Zhang W. Aldosterone-Regulated Sodium Transport and Blood Pressure. Front Physiol 2022; 13:770375. [PMID: 35197862 PMCID: PMC8859437 DOI: 10.3389/fphys.2022.770375] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 01/06/2022] [Indexed: 11/13/2022] Open
Abstract
Aldosterone is a major mineralocorticoid steroid hormone secreted by glomerulosa cells in the adrenal cortex. It regulates a variety of physiological responses including those to oxidative stress, inflammation, fluid disruption, and abnormal blood pressure through its actions on various tissues including the kidney, heart, and the central nervous system. Aldosterone synthesis is primarily regulated by angiotensin II, K+ concentration, and adrenocorticotrophic hormone. Elevated serum aldosterone levels increase blood pressure largely by increasing Na+ re-absorption in the kidney through regulating transcription and activity of the epithelial sodium channel (ENaC). This review focuses on the signaling pathways involved in aldosterone synthesis and its effects on Na+ reabsorption through ENaC.
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Affiliation(s)
- Akaki Tsilosani
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
| | - Chao Gao
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
| | - Wenzheng Zhang
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
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Cantero-Navarro E, Fernández-Fernández B, Ramos AM, Rayego-Mateos S, Rodrigues-Diez RR, Sánchez-Niño MD, Sanz AB, Ruiz-Ortega M, Ortiz A. Renin-angiotensin system and inflammation update. Mol Cell Endocrinol 2021; 529:111254. [PMID: 33798633 DOI: 10.1016/j.mce.2021.111254] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 02/05/2021] [Accepted: 03/18/2021] [Indexed: 12/12/2022]
Abstract
The most classical view of the renin-angiotensin system (RAS) emphasizes its role as an endocrine regulator of sodium balance and blood pressure. However, it has long become clear that the RAS has pleiotropic actions that contribute to organ damage, including modulation of inflammation. Angiotensin II (Ang II) activates angiotensin type 1 receptors (AT1R) to promote an inflammatory response and organ damage. This represents the pathophysiological basis for the successful use of RAS blockers to prevent and treat kidney and heart disease. However, other RAS components could have a built-in capacity to brake proinflammatory responses. Angiotensin type 2 receptor (AT2R) activation can oppose AT1R actions, such as vasodilatation, but its involvement in modulation of inflammation has not been conclusively proven. Angiotensin-converting enzyme 2 (ACE2) can process Ang II to generate angiotensin-(1-7) (Ang-(1-7)), that activates the Mas receptor to exert predominantly anti-inflammatory responses depending on the context. We now review recent advances in the understanding of the interaction of the RAS with inflammation. Specific topics in which novel information became available recently include intracellular angiotensin receptors; AT1R posttranslational modifications by tissue transglutaminase (TG2) and anti-AT1R autoimmunity; RAS modulation of lymphoid vessels and T lymphocyte responses, especially of Th17 and Treg responses; interactions with toll-like receptors (TLRs), programmed necrosis, and regulation of epigenetic modulators (e.g. microRNAs and bromodomain and extraterminal domain (BET) proteins). We additionally discuss an often overlooked effect of the RAS on inflammation which is the downregulation of anti-inflammatory factors such as klotho, peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α), transient receptor potential ankyrin 1 (TRPA1), SNF-related serine/threonine-protein kinase (SNRK), serine/threonine-protein phosphatase 6 catalytic subunit (Ppp6C) and n-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP). Both transcription factors, such as nuclear factor κB (NF-κB), and epigenetic regulators, such as miRNAs are involved in downmodulation of anti-inflammatory responses. A detailed analysis of pathways and targets for downmodulation of anti-inflammatory responses constitutes a novel frontier in RAS research.
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Affiliation(s)
- Elena Cantero-Navarro
- Molecular and Cellular Biology in Renal and Vascular Pathology. IIS-Fundación Jiménez Díaz-Universidad Autónoma, Madrid, Spain; Red de Investigación Renal (REDINREN), Spain
| | - Beatriz Fernández-Fernández
- Red de Investigación Renal (REDINREN), Spain; Unidad de Diálisis. IIS-Fundación Jiménez Díaz-Universidad Autónoma, Madrid, Spain
| | - Adrian M Ramos
- Red de Investigación Renal (REDINREN), Spain; Unidad de Diálisis. IIS-Fundación Jiménez Díaz-Universidad Autónoma, Madrid, Spain
| | - Sandra Rayego-Mateos
- Molecular and Cellular Biology in Renal and Vascular Pathology. IIS-Fundación Jiménez Díaz-Universidad Autónoma, Madrid, Spain; Red de Investigación Renal (REDINREN), Spain
| | - Raúl R Rodrigues-Diez
- Molecular and Cellular Biology in Renal and Vascular Pathology. IIS-Fundación Jiménez Díaz-Universidad Autónoma, Madrid, Spain; Red de Investigación Renal (REDINREN), Spain
| | - María Dolores Sánchez-Niño
- Red de Investigación Renal (REDINREN), Spain; Unidad de Diálisis. IIS-Fundación Jiménez Díaz-Universidad Autónoma, Madrid, Spain
| | - Ana B Sanz
- Red de Investigación Renal (REDINREN), Spain; Unidad de Diálisis. IIS-Fundación Jiménez Díaz-Universidad Autónoma, Madrid, Spain
| | - Marta Ruiz-Ortega
- Molecular and Cellular Biology in Renal and Vascular Pathology. IIS-Fundación Jiménez Díaz-Universidad Autónoma, Madrid, Spain; Red de Investigación Renal (REDINREN), Spain.
| | - Alberto Ortiz
- Red de Investigación Renal (REDINREN), Spain; Unidad de Diálisis. IIS-Fundación Jiménez Díaz-Universidad Autónoma, Madrid, Spain.
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Kanbay M, Demiray A, Afsar B, Covic A, Tapoi L, Ureche C, Ortiz A. Role of Klotho in the Development of Essential Hypertension. Hypertension 2021; 77:740-750. [PMID: 33423524 DOI: 10.1161/hypertensionaha.120.16635] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Klotho has antiaging properties, and serum levels decrease with physiological aging and aging-related diseases, such as hypertension, cardiovascular, and chronic kidney disease. Klotho deficiency in mice results in accelerated aging and cardiovascular injury, whereas Klotho supplementation slows down the progression of aging-related diseases. The pleiotropic functions of Klotho include, but are not limited to, inhibition of insulin/IGF-1 (insulin-like growth factor 1) and WNT (wingless-related integration site) signaling pathways, suppression of oxidative stress and aldosterone secretion, regulation of calcium-phosphate homeostasis, and modulation of autophagy with inhibition of apoptosis, fibrosis, and cell senescence. Accumulating evidence shows an interconnection between Klotho deficiency and hypertension, and Klotho gene polymorphisms are associated with hypertension in humans. In this review, we critically review the current understanding of the role of Klotho in the development of essential hypertension and the most important underlying pathways involved, such as the FGF23 (fibroblast growth factor 23)/Klotho axis, aldosterone, Wnt5a/RhoA, and SIRT1 (Sirtuin1). Based on this critical review, we suggest avenues for further research.
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Affiliation(s)
- Mehmet Kanbay
- From the Division of Nephrology, Department of Medicine (M.K.), Koc University School of Medicine, Istanbul, Turkey
| | - Atalay Demiray
- Department of Medicine (A.D.), Koc University School of Medicine, Istanbul, Turkey
| | - Baris Afsar
- Division of Nephrology, Department of Internal Medicine, Suleyman Demirel University School of Medicine, Isparta Turkey (B.A.)
| | - Adrian Covic
- Department of Nephrology, Grigore T. Popa University of Medicine, Iasi, Romania (A.C., L.T., C.U.)
| | - Laura Tapoi
- Department of Nephrology, Grigore T. Popa University of Medicine, Iasi, Romania (A.C., L.T., C.U.)
| | - Carina Ureche
- Department of Nephrology, Grigore T. Popa University of Medicine, Iasi, Romania (A.C., L.T., C.U.)
| | - Alberto Ortiz
- Cardiovascular Diseases Institute, Grigore T. Popa University of Medicine and Pharmacy, Iasi, Romania (A.O.)
- IIS-Fundacion Jimenez Diaz, Department of Medicine, School of Medicine, Universidad Autonoma de Madrid, Spain (A.O.)
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Düsing P, Zietzer A, Goody PR, Hosen MR, Kurts C, Nickenig G, Jansen F. Vascular pathologies in chronic kidney disease: pathophysiological mechanisms and novel therapeutic approaches. J Mol Med (Berl) 2021; 99:335-348. [PMID: 33481059 PMCID: PMC7900031 DOI: 10.1007/s00109-021-02037-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 12/14/2020] [Accepted: 01/05/2021] [Indexed: 12/13/2022]
Abstract
Cardiovascular disease (CVD) is a major cause of death in patients with chronic kidney disease (CKD). Both conditions are rising in incidence as well as prevalence, creating poor outcomes for patients and high healthcare costs. Recent data suggests CKD to be an independent risk factor for CVD. Accumulation of uremic toxins, chronic inflammation, and oxidative stress have been identified to act as CKD-specific alterations that increase cardiovascular risk. The association between CKD and cardiovascular mortality is markedly influenced through vascular alterations, in particular atherosclerosis and vascular calcification (VC). While numerous risk factors promote atherosclerosis by inducing endothelial dysfunction and its progress to vascular structural damage, CKD affects the medial layer of blood vessels primarily through VC. Ongoing research has identified VC to be a multifactorial, cell-mediated process in which numerous abnormalities like mineral dysregulation and especially hyperphosphatemia induce a phenotype switch of vascular smooth muscle cells to osteoblast-like cells. A combination of pro-calcifying stimuli and an impairment of inhibiting mechanisms like fetuin A and vitamin K-dependent proteins like matrix Gla protein and Gla-rich protein leads to mineralization of the extracellular matrix. In view of recent studies, intercellular communication pathways via extracellular vesicles and microRNAs represent key mechanisms in VC and thereby a promising field to a deeper understanding of the involved pathomechanisms. In this review, we provide an overview about pathophysiological mechanisms connecting CKD and CVD. Special emphasis is laid on vascular alterations and more recently discovered molecular pathways which present possible new therapeutic targets.
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Affiliation(s)
- Philip Düsing
- Heart Center, Department of Medicine II, University Hospital Bonn, University of Bonn, Venusberg-Campus 1, 53127, Bonn, Germany
| | - Andreas Zietzer
- Heart Center, Department of Medicine II, University Hospital Bonn, University of Bonn, Venusberg-Campus 1, 53127, Bonn, Germany
| | - Philip Roger Goody
- Heart Center, Department of Medicine II, University Hospital Bonn, University of Bonn, Venusberg-Campus 1, 53127, Bonn, Germany
| | - Mohammed Rabiul Hosen
- Heart Center, Department of Medicine II, University Hospital Bonn, University of Bonn, Venusberg-Campus 1, 53127, Bonn, Germany
| | - Christian Kurts
- Institute of Experimental Immunology, University Hospital Bonn, University of Bonn, Venusberg-Campus 1, Bonn, 53127, Germany
| | - Georg Nickenig
- Heart Center, Department of Medicine II, University Hospital Bonn, University of Bonn, Venusberg-Campus 1, 53127, Bonn, Germany
| | - Felix Jansen
- Heart Center, Department of Medicine II, University Hospital Bonn, University of Bonn, Venusberg-Campus 1, 53127, Bonn, Germany.
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Mencke R, Umbach AT, Wiggenhauser LM, Voelkl J, Olauson H, Harms G, Bulthuis M, Krenning G, Quintanilla-Martinez L, van Goor H, Lang F, Hillebrands JL. Klotho Deficiency Induces Arteriolar Hyalinosis in a Trade-Off with Vascular Calcification. THE AMERICAN JOURNAL OF PATHOLOGY 2019; 189:2503-2515. [DOI: 10.1016/j.ajpath.2019.08.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 08/11/2019] [Accepted: 08/19/2019] [Indexed: 02/07/2023]
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11
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Gueiros APS, Gueiros JEDB, Nóbrega KT, Calado EB, da Matta MC, Torres LC, Souza ASR, Casarini DE, de Carvalho AB. Effect of spironolactone on the progression of coronary calcification in peritoneal dialysis patients: a pilot study. J Bras Nefrol 2019; 41:345-355. [PMID: 31419271 PMCID: PMC6788848 DOI: 10.1590/2175-8239-jbn-2019-0009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/21/2019] [Indexed: 12/27/2022] Open
Abstract
INTRODUCTION There is evidence that aldosterone plays a role in the pathogenesis of vascular calcification. The aim of this study was to evaluate the effect of spironolactone, a mineralocorticoid receptor antagonist, on the progression of coronary calcification (CC) in peritoneal dialysis patients and to identify the factors involved in this progression. METHODS Thirty-three patients with a coronary calcium score (CCS) ≥ 30, detected through multi-detector computed tomography (MDCT) and expressed in Agatston units, were randomly assigned to a group receiving 25mg spironolactone per day for 12 months (spironolactone group) and a control group not receiving this drug. The primary outcome was a percentage change in CCS from baseline to end of the study (relative progression), when a further MDCT was conducted. Patients who had progression of CC were compared with those who did not progress. RESULTS Sixteen patients, seven in the spironolactone group and nine in the control group, concluded the study. The relative progression of the CCS was similar in both groups, 17.2% and 27.5% in the spironolactone and control groups respectively. Fifty-seven percent of the treated patients and 67% of those in the control group presented progression in the CC scores (p = 0.697). Progressor patients differed from non-progressors because they presented higher levels of calcium and low-density lipoprotein cholesterol and lower levels of albumin. CONCLUSION In peritoneal dialysis patients, spironolactone did not attenuate the progression of CC. However, large-scale studies are needed to confirm this observation. Disorders of mineral metabolism and dyslipidemia are involved in the progression of CC.
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Affiliation(s)
- Ana Paula Santana Gueiros
- Instituto de Medicina Integral Professor
Fernando FigueiraServiço de NefrologiaRecifePEBrasilInstituto de Medicina Integral Professor
Fernando Figueira, Serviço de Nefrologia, Recife, PE, Brasil.
| | - José Edevanilson de Barros Gueiros
- Instituto de Medicina Integral Professor
Fernando FigueiraServiço de NefrologiaRecifePEBrasilInstituto de Medicina Integral Professor
Fernando Figueira, Serviço de Nefrologia, Recife, PE, Brasil.
| | - Karina Tavares Nóbrega
- Instituto de Medicina Integral Professor
Fernando FigueiraServiço de RadiologiaRecifePEBrasilInstituto de Medicina Integral Professor
Fernando Figueira, Serviço de Radiologia, Recife, PE, Brasil.
| | - Eveline Barros Calado
- Instituto de Medicina Integral Professor
Fernando FigueiraServiço de RadiologiaRecifePEBrasilInstituto de Medicina Integral Professor
Fernando Figueira, Serviço de Radiologia, Recife, PE, Brasil.
| | - Marina Cadena da Matta
- Instituto de Medicina Integral Professor
Fernando FigueiraDepartamento de Pesquisa ClínicaRecifePEBrasilInstituto de Medicina Integral Professor
Fernando Figueira, Departamento de Pesquisa Clínica, Recife, PE,
Brasil.
| | - Leuridan Cavalcante Torres
- Instituto de Medicina Integral Professor
Fernando FigueiraDepartamento de Pesquisa ClínicaRecifePEBrasilInstituto de Medicina Integral Professor
Fernando Figueira, Departamento de Pesquisa Clínica, Recife, PE,
Brasil.
| | - Alex Sandro Rolland Souza
- Instituto de Medicina Integral Professor
Fernando FigueiraDepartamento de Pesquisa ClínicaRecifePEBrasilInstituto de Medicina Integral Professor
Fernando Figueira, Departamento de Pesquisa Clínica, Recife, PE,
Brasil.
| | - Dulce Elena Casarini
- Universidade Federal de São PauloSão PauloSPBrasilUniversidade Federal de São Paulo, Disciplina
de Nefrologia, São Paulo, SP, Brasil.
| | - Aluizio Barbosa de Carvalho
- Universidade Federal de São PauloSão PauloSPBrasilUniversidade Federal de São Paulo, Disciplina
de Nefrologia, São Paulo, SP, Brasil.
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12
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Takashi Y, Fukumoto S. FGF23 beyond Phosphotropic Hormone. Trends Endocrinol Metab 2018; 29:755-767. [PMID: 30217676 DOI: 10.1016/j.tem.2018.08.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 08/13/2018] [Accepted: 08/14/2018] [Indexed: 12/14/2022]
Abstract
Fibroblast growth factor (FGF) 23 is a bone-derived phosphotropic hormone that regulates phosphate and vitamin D metabolism. FGF23 mainly affects kidney function via the FGF receptor (FGFR)/α-Klotho complex. The physiological roles of FGF23 and α-Klotho in the regulation of mineral homeostasis have been well established. In addition, recent studies have reported that FGF23 has various effects on many other tissues, sometimes in an α-Klotho-independent manner, especially under pathological conditions. However, how FGF23 works in these tissues without α-Klotho is not entirely clear. Here we review the recent reports concerning the actions of FGF23 on various tissues and discuss the remaining questions about FGF23.
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Affiliation(s)
- Yuichi Takashi
- Diabetes Therapeutics and Research Center, Institute of Advanced Medical Sciences, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima, Tokushima 7708503, Japan; Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima, Tokushima 7708503, Japan
| | - Seiji Fukumoto
- Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima, Tokushima 7708503, Japan.
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13
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Mytych J, Romerowicz-Misielak M, Koziorowski M. Klotho protects human monocytes from LPS-induced immune impairment associated with immunosenescent-like phenotype. Mol Cell Endocrinol 2018; 470:1-13. [PMID: 28478304 DOI: 10.1016/j.mce.2017.05.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 04/30/2017] [Accepted: 05/02/2017] [Indexed: 12/01/2022]
Abstract
In this study, we provide a new evidence on immunosenescent-like phenotype induction in low density monocytes due to the long-term treatment with lipopolysaccharide (LPS). We show that LPS caused oxidative and nitrosative stress through zinc downregulation and calcium accumulation. In turn, increased amounts of ROS/RNS and pro-inflammatory cytokines TNFα, IL-1β, IL-6 led to the irreversible DNA damage, persistent DDR activation, proliferation inhibition, reduction in cell growth and immune impairment. Furthermore, we provide evidence that klotho reduced levels of ROS/RNS and pro-inflammatory cytokines as well as upregulated secretion of anti-inflammatory IL-10 in LPS-treated monocytes, thus the observed DNA damage was less severe, promptly and properly fixed and cells quickly resumed normal proliferation and maintained their immune functionality. Therefore, klotho protein could be considered as a protective factor against immunosenescent-like phenotype in monocytes an issue relevant to many immune disorders.
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Affiliation(s)
- Jennifer Mytych
- Institute of Applied Biotechnology and Basic Sciences, University of Rzeszow, Werynia 502, 36-100 Kolbuszowa, Poland; Centre of Applied Biotechnology and Basic Sciences, University of Rzeszow, Werynia 502, 36-100 Kolbuszowa, Poland.
| | - Maria Romerowicz-Misielak
- Institute of Applied Biotechnology and Basic Sciences, University of Rzeszow, Werynia 502, 36-100 Kolbuszowa, Poland; Centre of Applied Biotechnology and Basic Sciences, University of Rzeszow, Werynia 502, 36-100 Kolbuszowa, Poland
| | - Marek Koziorowski
- Institute of Applied Biotechnology and Basic Sciences, University of Rzeszow, Werynia 502, 36-100 Kolbuszowa, Poland; Centre of Applied Biotechnology and Basic Sciences, University of Rzeszow, Werynia 502, 36-100 Kolbuszowa, Poland
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14
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Rossaint J, Unruh M, Zarbock A. Fibroblast growth factor 23 actions in inflammation: a key factor in CKD outcomes. Nephrol Dial Transplant 2018; 32:1448-1453. [PMID: 27659127 DOI: 10.1093/ndt/gfw331] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 08/01/2016] [Indexed: 02/07/2023] Open
Abstract
During chronic kidney disease (CKD), bone mineral metabolism is disturbed owing in part to the endogenous hormone fibroblast growth factor 23 (FGF23). Elevated FGF23 levels are seen in CKD patients. Current research has demonstrated that FGF23 directly modulates the immune response and host defense to bacterial infections. FGF23 also impairs the activation and recruitment of neutrophils, which are the main immune effector cells required for host defense against bacterial infections. In addition, while FGF23 levels reduce leukocyte recruitment and functions, inflammatory conditions may also-in a reverse fashion-contribute to elevated FGF23 levels in the circulation. In this context, altered hypoxia inducible factor 1α signaling and iron metabolism may contribute to intact FGF23 (iFGF23) production. This review examines evidence on the role of FGF23 in inflammation, immune cell function and recruitment as well as the regulation of FGF23 during inflammation and the clinical implications of this process for the immune system in individuals with CKD. Clinical observations and laboratory investigations indicate an important role of FGF23 in directly modulating leukocyte activation and recruitment behavior with consequences on host defense against bacterial infections. This novel observation may in part explain the increased infectious risk among patients with CKD. However, studies of FGF23 neutralization also revealed increased mortality after sustained administration over several weeks in rats. Thus, therapeutic interventions targeting FGF23 must be carefully evaluated.
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Affiliation(s)
- Jan Rossaint
- Department of Anaesthesiology, Intensive Care and Pain Medicine, University Hospital Münster, Münster, Germany
| | - Mark Unruh
- Division of Nephrology, Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA.,Section of Neprology, New Mexico Veteran Affairs Hospital, Albuquerque, NM, USA
| | - Alexander Zarbock
- Department of Anaesthesiology, Intensive Care and Pain Medicine, University Hospital Münster, Münster, Germany
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15
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Kamr AM, Dembek KA, Hildreth BE, Morresey PR, Rathgeber RA, Burns TA, Zaghawa AA, Toribio RE. The FGF-23/klotho axis and its relationship with phosphorus, calcium, vitamin D, PTH, aldosterone, severity of disease, and outcome in hospitalised foals. Equine Vet J 2018; 50:739-746. [PMID: 29660161 DOI: 10.1111/evj.12946] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 03/30/2018] [Indexed: 01/12/2023]
Abstract
BACKGROUND Fibroblast growth factor-23 (FGF-23) and klotho are key regulators of vitamin D and parathyroid hormone (PTH) synthesis as well as phosphorus and calcium homeostasis; however, information on the FGF-23/klotho axis in healthy and hospitalised foals is lacking. OBJECTIVES The aims of this study were to measure serum FGF-23 and klotho concentrations and determine their association with serum phosphorus, total calcium (TCa), vitamin D metabolite [25(OH)D, 1,25(OH)2 D], PTH, and aldosterone concentrations, disease severity, and mortality in hospitalised foals. STUDY DESIGN Prospective, multicentre, cross-sectional study. METHODS A total of 91 foals ≤72 h old were classified as hospitalised (n = 81; 58 septic; 23 sick non-septic [SNS]) and healthy (n = 10). Blood samples were collected on admission. Hormone concentrations were determined by immunoassays. RESULTS Serum FGF-23, PTH, phosphorus, and aldosterone concentrations were higher while klotho, 25(OH)D, 1,25(OH)2 D, and TCa concentrations were lower in septic and SNS compared to healthy foals (P<0.05). In hospitalised and septic foals, increased FGF-23 and aldosterone concentrations were associated with high phosphorus and PTH but not with TCa and vitamin D metabolite concentrations. Hospitalised foals with the highest FGF-23 and lowest klotho concentrations were more likely to die (odds ratio (OR): 3.3; 95% confidence interval (CI): 1.1-10.3 and OR: 3.1; CI: 1.1-8.0, respectively). MAIN LIMITATIONS Blood gas, ionised calcium, blood culture information not being available for many foals, and use of the sepsis score to classify hospitalised foals. CONCLUSIONS Imbalances in the FGF-23/klotho axis may contribute to mineral dyshomeostasis and disease progression in critically ill foals. Elevated FGF-23 and reduced klotho, together with high phosphorus and PTH concentrations suggests FGF-23 resistance. FGF-23 and klotho are good markers of disease severity and likelihood of mortality in hospitalised foals. Aldosterone may influence phosphorus and PTH dynamics in hospitalised foals. Routine measurement of phosphorus concentrations in sick foals is recommended.
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Affiliation(s)
- A M Kamr
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA.,Faculty of Veterinary Medicine, University of Sadat City, Sadat City, Egypt
| | - K A Dembek
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA
| | - B E Hildreth
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA
| | - P R Morresey
- Rood and Riddle Equine Hospital, Lexington, Kentucky, USA
| | - R A Rathgeber
- Hagyard Equine Medical Institute, Lexington, Kentucky, USA
| | - T A Burns
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA
| | - A A Zaghawa
- Faculty of Veterinary Medicine, University of Sadat City, Sadat City, Egypt
| | - R E Toribio
- Faculty of Veterinary Medicine, University of Sadat City, Sadat City, Egypt
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16
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Coelho FO, Jorge LB, de Bragança Viciana AC, Sanches TR, Dos Santos F, Helou CMB, Irigoyen MC, Kuro-O M, Andrade L. Chronic nicotine exposure reduces klotho expression and triggers different renal and hemodynamic responses in klotho-haploinsufficient mice. Am J Physiol Renal Physiol 2018; 314:F992-F998. [PMID: 29363324 DOI: 10.1152/ajprenal.00442.2016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The klotho gene, which encodes a single-pass transmembrane protein and a secreted protein, is expressed predominantly by the distal renal tubules and is related to calcium phosphorus metabolism, ion channel regulation, intracellular signaling pathways, and longevity. Klotho deficiency aggravates acute kidney injury and renal fibrosis. Exposure to nicotine also worsens kidney injury. Here, we investigated renal Klotho protein expression in a mouse model of chronic (28-day) nicotine exposure, in which mice received nicotine or vehicle (saccharine) in drinking water, comparing wild-type (WT) mice, klotho-haploinsufficient ( kl/+) mice, and their respective controls, in terms of the effects of that exposure. Nicotine exposure was associated with a significant decline in renal Klotho expression in WT and kl/+ mice as well as a reduction in the glomerular filtration rate in WT mice. Although plasma electrolytes were similar among the groups, fractional excretion of sodium was reduced in both nicotine-exposed groups. The nicotine-WT mice presented augmented baroreflex sensitivity to nitroprusside and augmented sympathetic cardiac modulation. However, nicotine- kl/+ mice presented higher plasma levels of urea and aldosterone together with a higher α-index (spontaneous baroreflex) and higher peripheral sympathetic modulation, as evaluated by spectral analysis. We can conclude that nicotine downregulates Klotho expression as well as that renal and autonomic responses to nicotine exposure are modified in kl/+ mice.
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Affiliation(s)
| | | | | | - Talita R Sanches
- Division of Nephrology, University of São Paulo School of Medicine , São Paulo , Brazil
| | - Fernando Dos Santos
- Hypertension Unit, Heart Institute, University of São Paulo , São Paulo , Brazil
| | - Claudia M B Helou
- Division of Nephrology, University of São Paulo School of Medicine , São Paulo , Brazil
| | | | - Makoto Kuro-O
- Molecular Medicine Department, Jichi Medical University , Tochigi , Japan
| | - Lucia Andrade
- Division of Nephrology, University of São Paulo School of Medicine , São Paulo , Brazil
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17
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Lang F, Leibrock C, Pelzl L, Gawaz M, Pieske B, Alesutan I, Voelkl J. Therapeutic Interference With Vascular Calcification-Lessons From Klotho-Hypomorphic Mice and Beyond. Front Endocrinol (Lausanne) 2018; 9:207. [PMID: 29780355 PMCID: PMC5945862 DOI: 10.3389/fendo.2018.00207] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 04/13/2018] [Indexed: 12/13/2022] Open
Abstract
Medial vascular calcification, a major pathophysiological process associated with cardiovascular disease and mortality, involves osteo-/chondrogenic transdifferentiation of vascular smooth muscle cells (VSMCs). In chronic kidney disease (CKD), osteo-/chondrogenic transdifferentiation of VSMCs and, thus, vascular calcification is mainly driven by hyperphosphatemia, resulting from impaired elimination of phosphate by the diseased kidneys. Hyperphosphatemia with subsequent vascular calcification is a hallmark of klotho-hypomorphic mice, which are characterized by rapid development of multiple age-related disorders and early death. In those animals, hyperphosphatemia results from unrestrained formation of 1,25(OH)2D3 with subsequent retention of calcium and phosphate. Analysis of klotho-hypomorphic mice and mice with vitamin D3 overload uncovered several pathophysiological mechanisms participating in the orchestration of vascular calcification and several therapeutic opportunities to delay or even halt vascular calcification. The present brief review addresses the beneficial effects of bicarbonate, carbonic anhydrase inhibition, magnesium supplementation, mineralocorticoid receptor (MR) blockage, and ammonium salts. The case is made that bicarbonate is mainly effective by decreasing intestinal phosphate absorption, and that carbonic anhydrase inhibition leads to metabolic acidosis, which counteracts calcium-phosphate precipitation and VSMC transdifferentiation. Magnesium supplementation, MR blockage and ammonium salts are mainly effective by interference with osteo-/chondrogenic signaling in VSMCs. It should be pointed out that the, by far, most efficient substances are ammonium salts, which may virtually prevent vascular calcification. Future research will probably uncover further therapeutic options and, most importantly, reveal whether these observations in mice can be translated into treatment of patients suffering from vascular calcification, such as patients with CKD.
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Affiliation(s)
- Florian Lang
- Department of Physiology I, Eberhard Karls-University, Tübingen, Germany
- *Correspondence: Florian Lang,
| | - Christina Leibrock
- Department of Physiology I, Eberhard Karls-University, Tübingen, Germany
- Fresenius Kabi Deutschland GmbH, Bad Homburg, Germany
| | - Lisann Pelzl
- Department of Physiology I, Eberhard Karls-University, Tübingen, Germany
| | - Meinrad Gawaz
- Department of Internal Medicine III, Eberhard Karls-University, Tübingen, Germany
| | - Burkert Pieske
- Department of Internal Medicine and Cardiology, Charité-Universität Medizin Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
- Partner Site Berlin, German Centre for Cardiovascular Research (DZHK), Berlin, Germany
| | - Ioana Alesutan
- Department of Internal Medicine and Cardiology, Charité-Universität Medizin Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
- Partner Site Berlin, German Centre for Cardiovascular Research (DZHK), Berlin, Germany
| | - Jakob Voelkl
- Department of Internal Medicine and Cardiology, Charité-Universität Medizin Berlin, Berlin, Germany
- Partner Site Berlin, German Centre for Cardiovascular Research (DZHK), Berlin, Germany
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18
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Alesutan I, Voelkl J, Feger M, Kratschmar DV, Castor T, Mia S, Sacherer M, Viereck R, Borst O, Leibrock C, Gawaz M, Kuro-O M, Pilz S, Tomaschitz A, Odermatt A, Pieske B, Wagner CA, Lang F. Involvement Of Vascular Aldosterone Synthase In Phosphate-Induced Osteogenic Transformation Of Vascular Smooth Muscle Cells. Sci Rep 2017; 7:2059. [PMID: 28515448 PMCID: PMC5435689 DOI: 10.1038/s41598-017-01882-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 04/04/2017] [Indexed: 02/07/2023] Open
Abstract
Vascular calcification resulting from hyperphosphatemia is a major determinant of mortality in chronic kidney disease (CKD). Vascular calcification is driven by aldosterone-sensitive osteogenic transformation of vascular smooth muscle cells (VSMCs). We show that even in absence of exogenous aldosterone, silencing and pharmacological inhibition (spironolactone, eplerenone) of the mineralocorticoid receptor (MR) ameliorated phosphate-induced osteo-/chondrogenic transformation of primary human aortic smooth muscle cells (HAoSMCs). High phosphate concentrations up-regulated aldosterone synthase (CYP11B2) expression in HAoSMCs. Silencing and deficiency of CYP11B2 in VSMCs ameliorated phosphate-induced osteogenic reprogramming and calcification. Phosphate treatment was followed by nuclear export of APEX1, a CYP11B2 transcriptional repressor. APEX1 silencing up-regulated CYP11B2 expression and stimulated osteo-/chondrogenic transformation. APEX1 overexpression blunted the phosphate-induced osteo-/chondrogenic transformation and calcification of HAoSMCs. Cyp11b2 expression was higher in aortic tissue of hyperphosphatemic klotho-hypomorphic (kl/kl) mice than in wild-type mice. In adrenalectomized kl/kl mice, spironolactone treatment still significantly ameliorated aortic osteoinductive reprogramming. Our findings suggest that VSMCs express aldosterone synthase, which is up-regulated by phosphate-induced disruption of APEX1-dependent gene suppression. Vascular CYP11B2 may contribute to stimulation of VSMCs osteo-/chondrogenic transformation during hyperphosphatemia.
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Affiliation(s)
- Ioana Alesutan
- Department of Physiology, University of Tübingen, Tübingen, Germany
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Jakob Voelkl
- Department of Physiology, University of Tübingen, Tübingen, Germany
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Berlin, Germany
| | - Martina Feger
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Denise V Kratschmar
- Department of Pharmaceutical Sciences, and the National Center for Excellence in Research NCCR Kidney.CH, University of Basel, Basel, Switzerland
| | - Tatsiana Castor
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Sobuj Mia
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Michael Sacherer
- Div. of Cardiology, Medical University of Graz and Ludwig Boltzmann Institute for Translational Heart Failure Research, Graz, Austria
| | - Robert Viereck
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Oliver Borst
- Department of Physiology, University of Tübingen, Tübingen, Germany
- Department of Cardiology and Cardiovascular Medicine, University of Tübingen, Tübingen, Germany
| | | | - Meinrad Gawaz
- Department of Cardiology and Cardiovascular Medicine, University of Tübingen, Tübingen, Germany
| | - Makoto Kuro-O
- Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Stefan Pilz
- Department of Internal Medicine, Division of Endocrinology and Metabolism, Medical University of Graz, Graz, Austria
| | - Andreas Tomaschitz
- Div. of Cardiology, Medical University of Graz and Ludwig Boltzmann Institute for Translational Heart Failure Research, Graz, Austria
- Bad Gleichenberg Clinic, Bad Gleichenberg, Austria
| | - Alex Odermatt
- Department of Pharmaceutical Sciences, and the National Center for Excellence in Research NCCR Kidney.CH, University of Basel, Basel, Switzerland
| | - Burkert Pieske
- Department of Internal Medicine and Cardiology, Charité University Medicine, Campus Virchow-Klinikum, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
- Department of Cardiology, University of Graz, Graz, Austria; Department of Internal Medicine and Cardiology, German Heart Center Berlin (DHZB), Berlin, Germany
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, and the National Center for Excellence in Research NCCR Kidney, Zurich, Switzerland
| | - Florian Lang
- Department of Physiology, University of Tübingen, Tübingen, Germany.
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Mencke R, Hillebrands JL. The role of the anti-ageing protein Klotho in vascular physiology and pathophysiology. Ageing Res Rev 2017; 35:124-146. [PMID: 27693241 DOI: 10.1016/j.arr.2016.09.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/23/2016] [Indexed: 02/08/2023]
Abstract
Klotho is an anti-ageing protein that functions in many pathways that govern ageing, like regulation of phosphate homeostasis, insulin signaling, and Wnt signaling. Klotho expression levels and levels in blood decline during ageing. The vascular phenotype of Klotho deficiency features medial calcification, intima hyperplasia, endothelial dysfunction, arterial stiffening, hypertension, and impaired angiogenesis and vasculogenesis, with characteristics similar to aged human arteries. Klotho-deficient phenotypes can be prevented and rescued by Klotho gene expression or protein supplementation. High phosphate levels are likely to be directly pathogenic and are a prerequisite for medial calcification, but more important determinants are pathways that regulate cellular senescence, suggesting that deficiency of Klotho renders cells susceptible to phosphate toxicity. Overexpression of Klotho is shown to ameliorate medial calcification, endothelial dysfunction, and hypertension. Endogenous vascular Klotho expression is a controversial subject and, currently, no compelling evidence exists that supports the existence of vascular membrane-bound Klotho expression, as expressed in kidney. In vitro, Klotho has been shown to decrease oxidative stress and apoptosis in both SMCs and ECs, to reduce SMC calcification, to maintain the contractile SMC phenotype, and to prevent μ-calpain overactivation in ECs. Klotho has many protective effects with regard to the vasculature and constitutes a very promising therapeutic target. The purpose of this review is to explore the etiology of the vascular phenotype of Klotho deficiency and the therapeutic potential of Klotho in vascular disease.
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20
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Alesutan I, Feger M, Tuffaha R, Castor T, Musculus K, Buehling SS, Heine CL, Kuro-O M, Pieske B, Schmidt K, Tomaschitz A, Maerz W, Pilz S, Meinitzer A, Voelkl J, Lang F. Augmentation of phosphate-induced osteo-/chondrogenic transformation of vascular smooth muscle cells by homoarginine. Cardiovasc Res 2016; 110:408-418. [DOI: 10.1093/cvr/cvw062] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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21
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Gao J, Zhang K, Chen J, Wang MH, Wang J, Liu P, Huang H. Roles of aldosterone in vascular calcification: An update. Eur J Pharmacol 2016; 786:186-193. [PMID: 27238972 DOI: 10.1016/j.ejphar.2016.05.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 05/20/2016] [Accepted: 05/25/2016] [Indexed: 10/21/2022]
Abstract
Both clinical and experimental studies have demonstrated that vascular calcification (VC) is a common pathology shared in many chronic diseases such as chronic kidney disease (CKD) and diabetes. It's an independent risk factor for cardiovascular events. Since the pathogenesis of VC is complicated, current therapies have limited effects on the regression of VC. Therefore, it is urgent to investigate the potential mechanisms and find new targets for the treatment of VC. Aldosterone (Aldo), a mineralocorticoid hormone, is the metabolite of renin-angiotensin-aldosterone system (RAAS) activation, which can exert genomic and non-genomic effects on the cardiovascular system. Recent data suggests that Aldo can promote VC. Here, we summarized the roles of Aldo in the process of VC and a series of findings indicated that Aldo could act as a potentially therapeutic target for treating VC.
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Affiliation(s)
- Jingwei Gao
- Department of Cardiology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou 510120 China; Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou 510120, China
| | - Kun Zhang
- Department of Cardiology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou 510120 China; Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou 510120, China
| | - Jie Chen
- Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou 510120, China; Department of Radiation Oncology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou 510120, China
| | - Mong-Heng Wang
- Department of Physiology, Georgia Regents University, Augusta, GA 30912, United States
| | - Jingfeng Wang
- Department of Cardiology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou 510120 China; Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou 510120, China
| | - Pinming Liu
- Department of Cardiology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou 510120 China; Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou 510120, China
| | - Hui Huang
- Department of Cardiology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou 510120 China; Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou 510120, China.
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Leibrock CB, Voelkl J, Kuro-O M, Lang F, Lang UE. 1,25(OH)2D3 dependent overt hyperactivity phenotype in klotho-hypomorphic mice. Sci Rep 2016; 6:24879. [PMID: 27109615 PMCID: PMC4843009 DOI: 10.1038/srep24879] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/05/2016] [Indexed: 02/06/2023] Open
Abstract
Klotho, a protein mainly expressed in kidney and cerebral choroid plexus, is a powerful regulator of 1,25(OH)2D3 formation. Klotho-deficient mice (kl/kl) suffer from excessive plasma 1,25(OH)2D3-, Ca2+- and phosphate-concentrations, leading to severe soft tissue calcification and accelerated aging. NH4Cl treatment prevents tissue calcification and premature ageing without affecting 1,25(OH)2D3-formation. The present study explored the impact of excessive 1,25(OH)2D3 formation in NH4Cl-treated kl/kl-mice on behavior. To this end kl/kl-mice and wild-type mice were treated with NH4Cl and either control diet or vitamin D deficient diet (LVD). As a result, plasma 1,25(OH)2D3-, Ca2+- and phosphate-concentrations were significantly higher in untreated and in NH4Cl-treated kl/kl-mice than in wild-type mice, a difference abrogated by LVD. In each, open field, dark-light box, and O-maze NH4Cl-treated kl/kl-mice showed significantly higher exploratory behavior than untreated wild-type mice, a difference abrogated by LVD. The time of floating in the forced swimming test was significantly shorter in NH4Cl treated kl/kl-mice compared to untreated wild-type mice and to kl/kl-mice on LVD. In wild-type animals, NH4Cl treatment did not significantly alter 1,25(OH)2D3, calcium and phosphate concentrations or exploratory behavior. In conclusion, the excessive 1,25(OH)2D3 formation in klotho-hypomorphic mice has a profound effect on murine behavior.
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Affiliation(s)
- Christina B Leibrock
- Department of Physiology, Cardiology &Vascular Medicine, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany
| | - Jakob Voelkl
- Department of Physiology, Cardiology &Vascular Medicine, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany
| | - Makoto Kuro-O
- Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
| | - Florian Lang
- Department of Physiology, Cardiology &Vascular Medicine, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany
| | - Undine E Lang
- Department of Psychiatry, University of Basel, Wilhelm Klein-Strasse 27, CH-4012 Basel, Switzerland
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Dounousi E, Torino C, Pizzini P, Cutrupi S, Panuccio V, D'Arrigo G, Abd ElHafeez S, Tripepi G, Mallamaci F, Zoccali C. Intact FGF23 and α-Klotho during acute inflammation/sepsis in CKD patients. Eur J Clin Invest 2016; 46:234-41. [PMID: 26728476 DOI: 10.1111/eci.12588] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 12/30/2015] [Indexed: 12/17/2022]
Abstract
BACKGROUND High FGF23 and low α-Klotho levels associate with systemic inflammation and reduced nitric oxide (NO) bioavailability, but the dynamics of this relationship in patients with CKD has not been investigated. METHODS We sequentially measured serum intact FGF23 and carboxyl-terminal (iFGF23, cFGF23), the iFGF23/cFGF23 ratio, αKlotho, biomarkers of inflammation (hs-CRP, IL-6 and TNF-α) and sepsis (procalcitonin), nitrotyrosine (reflecting NO synthesis and oxidative stress), serum iron and ferritin and CKD-MBD biomarkers, PTH, 25(OH)VD, 1,25(OH)2 VD at peak of intercurrent sepsis and after complete resolution in a series of 17 patients with CKD. RESULTS At peak infection, biomarkers of inflammation/sepsis, ferritin and nitrotyrosine were all very high (all P < 0·01) and declined towards the normal range thereafter (P < 0·01). iFGF23 was 191 ± 10 pg/ml (geometric mean, SD) and doubled to 371 ± 8 pg/ml (P = 0·003) after the resolution of infection, while cFGF23 did not change (246 ± 5 pg/mL vs. 248 ± 5 pg/mL, P = 0·50). As a consequence, the iFGF23/cFGF23 ratio, an indicator of the proteolytic cleavage of the FGF23 molecule, was 0·78 ± 3·87 at peak infection and increased to 1·49 ± 3·00 after resolution of infection (P < 0·001). In contrast, serum α-Klotho levels were upregulated at peak infection (peak infection: 526 ± 4 pg/ml, postinfection: 447 ± 4 pg/ml, P = 0·001). The eGFR, PTH and vitamin D did not change significantly throughout. CONCLUSIONS Acute inflammation/sepsis suppresses the active form of FGF23 and activates α-Klotho, the latter effect being likely attributable to enhance proteolysis of FGF23 molecule. iFGF23 downregulation and α-Klotho upregulation during acute sepsis may participate into the counter-regulatory response to severe inflammation in CKD patients with sepsis.
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Affiliation(s)
- Evangelia Dounousi
- Department of Nephrology, Medical School, University of Ioannina, Ioannina, Greece
| | - Claudia Torino
- Clinical Epidemiology and Physiopathology of Renal Diseases and Hypertension, CNR-IFC, Reggio Calabria, Italy
| | - Patrizia Pizzini
- Clinical Epidemiology and Physiopathology of Renal Diseases and Hypertension, CNR-IFC, Reggio Calabria, Italy
| | - Sebastiano Cutrupi
- Clinical Epidemiology and Physiopathology of Renal Diseases and Hypertension, CNR-IFC, Reggio Calabria, Italy
| | - Vincenzo Panuccio
- Clinical Epidemiology and Physiopathology of Renal Diseases and Hypertension, CNR-IFC, Reggio Calabria, Italy.,Renal Unit, Reggio Calabria, Italy
| | - Graziella D'Arrigo
- Clinical Epidemiology and Physiopathology of Renal Diseases and Hypertension, CNR-IFC, Reggio Calabria, Italy
| | | | - Giovanni Tripepi
- Clinical Epidemiology and Physiopathology of Renal Diseases and Hypertension, CNR-IFC, Reggio Calabria, Italy
| | - Francesca Mallamaci
- Clinical Epidemiology and Physiopathology of Renal Diseases and Hypertension, CNR-IFC, Reggio Calabria, Italy.,Renal Unit, Reggio Calabria, Italy
| | - Carmine Zoccali
- Clinical Epidemiology and Physiopathology of Renal Diseases and Hypertension, CNR-IFC, Reggio Calabria, Italy
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Leibrock CB, Voelkl J, Kohlhofer U, Quintanilla-Martinez L, Kuro-O M, Lang F. Bicarbonate-sensitive calcification and lifespan of klotho-deficient mice. Am J Physiol Renal Physiol 2015; 310:F102-8. [PMID: 26538435 DOI: 10.1152/ajprenal.00037.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 11/02/2015] [Indexed: 01/03/2023] Open
Abstract
Klotho, a protein counteracting aging, is a powerful inhibitor of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] formation and regulator of mineral metabolism. In klotho hypomorphic (kl/kl) mice, excessive 1,25(OH)2D3 formation leads to hypercalcemia, hyperphosphatemia and vascular calcification, severe growth deficits, accelerated aging and early death. Kl/kl mice further suffer from extracellular volume depletion and hypotension, leading to the stimulation of antidiuretic hormone and aldosterone release. A vitamin D-deficient diet, restriction of dietary phosphate, inhibition of mineralocorticoid receptors with spironolactone, and dietary NaCl all extend the lifespan of kl/kl mice. Kl/kl mice suffer from acidosis. The present study explored whether replacement of tap drinking water by 150 mM NaHCO3 affects the growth, tissue calcification, and lifespan of kl/kl mice. As a result, NaHCO3 administration to kl/kl mice did not reverse the growth deficit but substantially decreased tissue calcification and significantly increased the average lifespan from 78 to 127 days. NaHCO3 did not significantly affect plasma concentrations of 1,25(OH)2D3 and Ca(2+) but significantly decreased plasma phosphate concentration and plasma aldosterone concentration. The present study reveals a novel effect of bicarbonate, i.e., a favorable influence on vascular calcification and early death of klotho-deficient mice.
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Affiliation(s)
| | - Jakob Voelkl
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Ursula Kohlhofer
- Department of Pathology, University of Tübingen, Tübingen, Germany; and
| | | | - Makoto Kuro-O
- Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Florian Lang
- Department of Physiology, University of Tübingen, Tübingen, Germany;
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25
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Zhou X, Chen K, Wang Y, Schuman M, Lei H, Sun Z. Antiaging Gene Klotho Regulates Adrenal CYP11B2 Expression and Aldosterone Synthesis. J Am Soc Nephrol 2015; 27:1765-76. [PMID: 26471128 DOI: 10.1681/asn.2015010093] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 08/27/2015] [Indexed: 12/11/2022] Open
Abstract
Deficiency of the antiaging gene Klotho (KL) induces renal damage and hypertension through unknown mechanisms. In this study, we assessed whether KL regulates expression of CYP11B2, a key rate-limiting enzyme in aldosterone synthesis, in adrenal glands. We found that haplodeficiency of KL(+/-) in mice increased the plasma level of aldosterone by 16 weeks of age, which coincided with spontaneous and persistent elevation of BP. Blockade of aldosterone actions by eplerenone reversed KL deficiency-induced hypertension and attenuated the kidney damage. Protein expression of CYP11B2 was upregulated in adrenal cortex of KL(+/-) mice. KL and CYP11B2 proteins colocalized in adrenal zona glomerulosa cells. Silencing of KL upregulated and overexpression of KL downregulated CYP11B2 expression in human adrenocortical cells. Notably, silencing of KL decreased expression of SF-1, a negative transcription factor of CYP11B2, but increased phosphorylation of ATF2, a positive transcription factor of CYP11B2, which may contribute to upregulation of CYP11B2 expression. Therefore, these results show that KL regulates adrenal CYP11B2 expression. KL deficiency-induced spontaneous hypertension and kidney damage may be partially attributed to the upregulation of CYP11B2 expression and aldosterone synthesis.
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Affiliation(s)
- Xiaoli Zhou
- Department of Cardiology, First Affiliated Hospital, Chongqing Medical University, Chongqing, China; and Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Kai Chen
- Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Yongjun Wang
- Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Mariano Schuman
- Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Han Lei
- Department of Cardiology, First Affiliated Hospital, Chongqing Medical University, Chongqing, China; and
| | - Zhongjie Sun
- Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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26
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Chen K, Zhou X, Sun Z. Haplodeficiency of Klotho Gene Causes Arterial Stiffening via Upregulation of Scleraxis Expression and Induction of Autophagy. Hypertension 2015; 66:1006-13. [PMID: 26324504 DOI: 10.1161/hypertensionaha.115.06033] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 08/09/2015] [Indexed: 12/11/2022]
Abstract
The prevalence of arterial stiffness increases with age, whereas the level of the aging-suppressor protein klotho decreases with age. The objective of this study is to assess whether haplodeficiency of klotho gene causes arterial stiffness and to investigate the underlying mechanism. Pulse wave velocity, a direct measure of arterial stiffness, was increased significantly in klotho heterozygous (klotho(+/-)) mice versus their age-matched wild-type (WT) littermates, suggesting that haplodeficiency of klotho causes arterial stiffening. Notably, plasma aldosterone levels were elevated significantly in klotho(+/-) mice. Treatment with eplerenone (6 mg/kg per day IP), an aldosterone receptor blocker, abolished klotho deficiency-induced arterial stiffening in klotho(+/-) mice. Klotho deficiency was associated with increased collagen and decreased elastin contents in the media of aortas. In addition, arterial matrix metalloproteinase-2, matrix metalloproteinase-9, and transforming growth factor-β1 expression and myofibroblast differentiation were increased in klotho(+/-) mice. These klotho deficiency-related changes can be blocked by eplerenone. Protein expression of scleraxis, a transcription factor for collagen synthesis, and LC3-II/LC3-I, an index of autophagy, were upregulated in aortas of klotho(+/-) mice, which can be abolished by eplerenone. In cultured mouse aortic smooth muscle cells, aldosterone increased collagen-1 expression that can be completely eliminated by small interfering RNA knockdown of scleraxis. Interestingly, aldosterone decreased elastin levels in smooth muscle cells, which can be abolished by small interfering RNA knockdown of Beclin-1, an autophagy-related gene. In conclusion, this study demonstrated for the first time that klotho deficiency-induced arterial stiffening may involve aldosterone-mediated upregulation of scleraxis and induction of autophagy, which led to increased collagen-1 expression and decreased elastin levels, respectively.
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Affiliation(s)
- Kai Chen
- From the Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (K.C., X.Z., Z.S.); and Department of Cardiology, the First Affiliated Hospital, Chongqing Medical University, Chongqing, China (X.Z.)
| | - Xiaoli Zhou
- From the Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (K.C., X.Z., Z.S.); and Department of Cardiology, the First Affiliated Hospital, Chongqing Medical University, Chongqing, China (X.Z.)
| | - Zhongjie Sun
- From the Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City (K.C., X.Z., Z.S.); and Department of Cardiology, the First Affiliated Hospital, Chongqing Medical University, Chongqing, China (X.Z.).
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27
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Acetazolamide sensitive tissue calcification and aging of klotho-hypomorphic mice. J Mol Med (Berl) 2015; 94:95-106. [PMID: 26307633 DOI: 10.1007/s00109-015-1331-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 07/07/2015] [Accepted: 07/31/2015] [Indexed: 12/25/2022]
Abstract
UNLABELLED Klotho, a protein expressed mainly in the kidney, is required for the inhibitory effect of FGF23 on renal 1,25(OH)2D3 formation. Klotho counteracts vascular calcification and diverse age-related disorders. Klotho-hypomorphic mice (kl/kl) suffer from severe vascular calcification and rapid aging. The calcification is at least in part caused by excessive 1,25(OH)2D3, Ca(2+), and phosphate concentrations in blood, which trigger osteogenic signaling including upregulation of alkaline phosphatase (Alpl). As precipitation of calcium and phosphate is fostered by alkaline pH, extracellular acidosis could counteract tissue calcification. In order to induce acidosis, acetazolamide was added to drinking water (0.8 g/l) of kl/kl and wild-type mice. As a result, acetazolamide treatment of kl/kl mice partially reversed the growth deficit, tripled the life span, almost completely reversed the calcifications in trachea, lung, kidney, stomach, intestine, and vascular tissues, the excessive aortic alkaline phosphatase mRNA levels and the plasma concentrations of osteoprotegerin, osteopontin as well as fetuin-A, without significantly decreasing FGF23, 1,25(OH)2D3, Ca(2+), and phosphate plasma concentrations. In primary human aortic smooth muscle cells, acidotic environment prevented phosphate-induced alkaline phosphatase mRNA expression. The present study reveals a completely novel effect of acetazolamide, i.e., interference with osteoinductive signaling and tissue calcification in kl/kl mice. KEY MESSAGES Klotho deficient (kl/kl) mice suffer from hyperphosphatemia with dramatic tissue calcification. Acetazolamide (ACM) treatment partially reversed the growth deficit of kl/kl mice. In kl/kl mice, ACM reversed tissue calcification despite continued hyperphosphatemia. ACM tripled the life span of kl/kl mice. In human aortic smooth muscle cells, low extracellular pH prevented osteogenic signaling.
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28
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Abstract
Aging is an inevitable and progressive biological process involving dysfunction and eventually destruction of every tissue and organ. This process is driven by a tightly regulated and complex interplay between genetic and acquired factors. Klotho is an antiaging gene encoding a single-pass transmembrane protein, klotho, which serves as an aging suppressor through a wide variety of mechanisms, such as antioxidation, antisenescence, antiautophagy, and modulation of many signaling pathways, including insulin-like growth factor and Wnt. Klotho deficiency activates Wnt expression and activity contributing to senescence and depletion of stem cells, which consequently triggers tissue atrophy and fibrosis. In contrast, the klotho protein was shown to suppress Wnt-signaling transduction, and inhibit cell senescence and preserve stem cells. A better understanding of the potential effects of klotho on stem cells could offer novel insights into the cellular and molecular mechanisms of klotho deficiency-related aging and disease. The klotho protein may be a promising therapeutic agent for aging and aging-related disorders.
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Affiliation(s)
- Ao Bian
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA ; Department of Nephrology, First Affiliated Hospital of Nanjing Medical University, Nanjing, People's Republic of China
| | - Javier A Neyra
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, USA
| | - Ming Zhan
- Methodist Hospital Research Institute, Weill Cornell Medical College, Houston, TX, USA
| | - Ming Chang Hu
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA ; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, USA
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Santoro D, Caccamo D, Lucisano S, Buemi M, Sebekova K, Teta D, De Nicola L. Interplay of vitamin D, erythropoiesis, and the renin-angiotensin system. BIOMED RESEARCH INTERNATIONAL 2015; 2015:145828. [PMID: 26000281 PMCID: PMC4427087 DOI: 10.1155/2015/145828] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 01/30/2015] [Accepted: 02/04/2015] [Indexed: 12/20/2022]
Abstract
For many years deficiency of vitamin D was merely identified and assimilated to the presence of bone rickets. It is now clear that suboptimal vitamin D status may be correlated with several disorders and that the expression of 1-α-hydroxylase in tissues other than the kidney is widespread and of clinical relevance. Recently, evidence has been collected to suggest that, beyond the traditional involvement in mineral metabolism, vitamin D may interact with other kidney hormones such as renin and erythropoietin. This interaction would be responsible for some of the systemic and renal effects evoked for the therapy with vitamin D. The administration of analogues of vitamin D has been associated with an improvement of anaemia and reduction in ESA requirements. Moreover, vitamin D deficiency could contribute to an inappropriately activated or unsuppressed RAS, as a mechanism for progression of CKD and/or cardiovascular disease. Experimental data on the anti-RAS and anti-inflammatory effects treatment with active vitamin D analogues suggest a therapeutic option particularly in proteinuric CKD patients. This option should be considered for those subjects that are intolerant to anti-RAS agents or, as add-on therapy, in those already treated with anti-RAS but not reaching the safe threshold level of proteinuria.
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Affiliation(s)
- Domenico Santoro
- Department of Clinical and Experimental Medicine, University of Messina, Via Faranda, 2-98123 Messina, Italy
| | - Daniela Caccamo
- Department of Biomedical Sciences and Morphological and Functional Imaging, University of Messina, Italy
| | - Silvia Lucisano
- Department of Clinical and Experimental Medicine, University of Messina, Via Faranda, 2-98123 Messina, Italy
| | - Michele Buemi
- Department of Clinical and Experimental Medicine, University of Messina, Via Faranda, 2-98123 Messina, Italy
| | | | - Daniel Teta
- University Hospital (CHUV), Lausanne, Switzerland
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Tamma G, Goswami N, Reichmuth J, De Santo NG, Valenti G. Aquaporins, vasopressin, and aging: current perspectives. Endocrinology 2015; 156:777-88. [PMID: 25514088 DOI: 10.1210/en.2014-1812] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Functioning of the hypothalamic-neurohypophyseal-vasopressin axis is altered in aging, and the pathway may represent a plausible target to slow the process of aging. Arginine vasopressin, a nine-amino acid peptide that is secreted from the posterior pituitary in response to high plasma osmolality and hypotension, is central in this pathway. Vasopressin has important roles in circulatory and water homoeostasis mediated by vasopressin receptor subtypes V1a (vascular), V1b (pituitary), and V2 (vascular, renal). A dysfunction in this pathway as a result of aging can result in multiple abnormalities in several physiological systems. In addition, vasopressin plasma concentration is significantly higher in males than in females and vasopressin-mediated effects on renal and vascular targets are more pronounced in males than in females. These findings may be caused by sex differences in vasopressin secretion and action, making men more susceptible than females to diseases like hypertension, cardiovascular and chronic kidney diseases, and urolithiasis. Recently the availability of new, potent, orally active vasopressin receptor antagonists, the vaptans, has strongly increased the interest on vasopressin and its receptors as a new target for prevention of age-related diseases associated with its receptor-altered signaling. This review summarizes the recent literature in the field of vasopressin signaling in age-dependent abnormalities in kidney, cardiovascular function, and bone function.
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Affiliation(s)
- Grazia Tamma
- Department of Biosciences, Biotechnologies, and Biopharmaceutics (G.T., G.V.), University of Bari, 70125 Bari, Italy; Istituto Nazionale di Biostrutture e Biosistemi (G.T., G.V.), 00136 Roma, Italy; Gravitational Physiology and Medicine Research Unit (N.G., J.R.), Institute of Physiology, Medical University of Graz, 8036 Graz, Austria; Department of Medicine (N.G.D.S.), Second University of Naples, 80138 Naples, Italy; and Centro di Eccellenza di Genomica (G.V.) Campo Biomedico Ed Agrario, University of Bari, 70126 Bari, Italy
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31
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Leibrock CB, Alesutan I, Voelkl J, Pakladok T, Michael D, Schleicher E, Kamyabi-Moghaddam Z, Quintanilla-Martinez L, Kuro-o M, Lang F. NH4Cl Treatment Prevents Tissue Calcification in Klotho Deficiency. J Am Soc Nephrol 2015; 26:2423-33. [PMID: 25644113 DOI: 10.1681/asn.2014030230] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 11/30/2014] [Indexed: 11/03/2022] Open
Abstract
Klotho, a cofactor in suppressing 1,25(OH)2D3 formation, is a powerful regulator of mineral metabolism. Klotho-hypomorphic mice (kl/kl) exhibit excessive plasma 1,25(OH)2D3, Ca(2+), and phosphate concentrations, severe tissue calcification, volume depletion with hyperaldosteronism, and early death. Calcification is paralleled by overexpression of osteoinductive transcription factor Runx2/Cbfa1, Alpl, and senescence-associated molecules Tgfb1, Pai-1, p21, and Glb1. Here, we show that NH4Cl treatment in drinking water (0.28 M) prevented soft tissue and vascular calcification and increased the life span of kl/kl mice >12-fold in males and >4-fold in females without significantly affecting extracellular pH or plasma concentrations of 1,25(OH)2D3, Ca(2+), and phosphate. NH4Cl treatment significantly decreased plasma aldosterone and antidiuretic hormone concentrations and reversed the increase of Runx2/Cbfa1, Alpl, Tgfb1, Pai-1, p21, and Glb1 expression in aorta of kl/kl mice. Similarly, in primary human aortic smooth muscle cells (HAoSMCs), NH4Cl treatment reduced phosphate-induced mRNA expression of RUNX2/CBFA1, ALPL, and senescence-associated molecules. In both kl/kl mice and phosphate-treated HAoSMCs, levels of osmosensitive transcription factor NFAT5 and NFAT5-downstream mediator SOX9 were higher than in controls and decreased after NH4Cl treatment. Overexpression of NFAT5 in HAoSMCs mimicked the effect of phosphate and abrogated the effect of NH4Cl on SOX9, RUNX2/CBFA1, and ALPL mRNA expression. TGFB1 treatment of HAoSMCs upregulated NFAT5 expression and prevented the decrease of phosphate-induced NFAT5 expression after NH4Cl treatment. In conclusion, NH4Cl treatment prevents tissue calcification, reduces vascular senescence, and extends survival of klotho-hypomorphic mice. The effects of NH4Cl on vascular osteoinduction involve decrease of TGFB1 and inhibition of NFAT5-dependent osteochondrogenic signaling.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Makoto Kuro-o
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, Texas
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32
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Lang F, Ritz E, Alesutan I, Voelkl J. Impact of aldosterone on osteoinductive signaling and vascular calcification. Nephron Clin Pract 2014; 128:40-5. [PMID: 25377380 DOI: 10.1159/000368268] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Vascular calcification is frequently found already in early stages of chronic kidney disease (CKD) patients and is associated with high cardiovascular risk. The process of vascular calcification is not considered a passive phenomenon but involves, at least in part, phenotypical transformation of vascular smooth muscle cells (VSMCs). Following exposure to excessive extracellular phosphate concentrations, VSMCs undergo a reprogramming into osteo-/chondroblast-like cells. Such 'vascular osteoinduction' is characterized by expression of osteogenic transcription factors and triggered by increased phosphate concentrations. A key role in this process is assigned to cellular phosphate transporters, most notably the type III sodium-dependent phosphate transporter Pit1. Pit1 expression is stimulated by mineralocorticoid receptor activation. Therefore, aldosterone participates in the phenotypical transformation of VSMCs. In preclinical models, aldosterone antagonism reduces vascular osteoinduction. Patients with CKD suffer from hyperphosphatemia predisposing to vascular osteogenic transformation, potentially further fostered by concomitant hyperaldosteronism. Clearly, additional research is required to define the role of aldosterone in the regulation of osteogenic signaling and the consecutive vascular calcification in CKD, but more generally also other diseases associated with excessive vascular calcification and even in individuals without overt disease.
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Affiliation(s)
- Florian Lang
- Department of Physiology, University of Tübingen, Tübingen, Germany
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33
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Abstract
Chronic kidney disease (CKD) is becoming a worldwide epidemic, driven largely by the dramatic rise in the prevalence of diabetes and obesity. Novel targets and treatments for CKD are, therefore, desperately needed-to both mitigate the burden of this disease in the general population and reduce the necessity for renal replacement therapy in individual patients. This Review highlights new insights into the mechanisms that contribute to CKD, and approaches that might facilitate the development of disease-arresting therapies for CKD. Particular focus is given to therapeutic approaches using antifibrotic agents that target the transforming growth factor β superfamily. In addition, we discuss new insights regarding the roles of vascular calcification, the NADPH oxidase family, and inflammation in the pathogenesis of CKD. We also highlight a new understanding regarding kidney energy sensing pathways (AMPK, sirtuins, and mTOR) in a variety of kidney diseases and how they are linked to inflammation and fibrosis. Finally, exciting new insights have been made into the role of mitochondrial function and mitochondrial biogenesis in relation to progressive kidney disease. Prospective therapeutics based on these findings will hopefully renew hope for clinicians and patients in the near future.
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Affiliation(s)
- Anne-Emilie Declèves
- Laboratory of Experimental Nephrology, Faculty of Medicine, Université Libre de Bruxelles (ULB), CP603, 808 Route de Lennik, 1070 Brussels, Belgium
| | - Kumar Sharma
- Center for Renal Translational Medicine, University of California, San Diego and Veterans Affairs San Diego Healthcare System, Stein Clinical Research Building, 4th Floor, 9500 Gilman Drive, La Jolla, CA 92093-0711, USA
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Borst O, Münzer P, Schmid E, Schmidt E, Russo A, Walker B, Yang W, Leibrock C, Szteyn K, Schmidt S, Elvers M, Faggio C, Shumilina E, Kuro‐o M, Gawaz M, Lang F. 1,25(OH)
2
vitamin D
3
‐dependent inhibition of platelet Ca
2+
signaling and thrombus formation in klotho‐deficient mice. FASEB J 2014; 28:2108-2119. [DOI: 10.1096/fj.13-239277] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Affiliation(s)
- Oliver Borst
- Department of Cardiology and Cardiovascular MedicineUniversity of TübingenTübingenGermany
- Department of PhysiologyUniversity of TübingenTübingenGermany
| | - Patrick Münzer
- Department of PhysiologyUniversity of TübingenTübingenGermany
| | - Evi Schmid
- Department of PhysiologyUniversity of TübingenTübingenGermany
| | - Eva‐Maria Schmidt
- Department of PhysiologyUniversity of TübingenTübingenGermany
- Department of Behavioral NeurobiologyUniversity of TübingenTübingenGermany
| | - Antonella Russo
- Department of PhysiologyUniversity of TübingenTübingenGermany
- Department of Biological and Environmental SciencesUniversity of MessinaSant'Agata‐MessinaItaly
| | - Britta Walker
- Department of PhysiologyUniversity of TübingenTübingenGermany
| | - Wenting Yang
- Department of PhysiologyUniversity of TübingenTübingenGermany
| | | | - Kalina Szteyn
- Department of PhysiologyUniversity of TübingenTübingenGermany
| | | | - Margitta Elvers
- Department of Cardiology and Cardiovascular MedicineUniversity of TübingenTübingenGermany
- Department of Clinical and Experimental HemostasisUniversity of DüsseldorfDüsseldorfGermany
| | - Caterina Faggio
- Department of Behavioral NeurobiologyUniversity of TübingenTübingenGermany
| | | | - Makoto Kuro‐o
- Department of PathologyUniversity of TexasDallasTexasUSA
| | - Meinrad Gawaz
- Department of Cardiology and Cardiovascular MedicineUniversity of TübingenTübingenGermany
| | - Florian Lang
- Department of PhysiologyUniversity of TübingenTübingenGermany
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PAI-1-regulated extracellular proteolysis governs senescence and survival in Klotho mice. Proc Natl Acad Sci U S A 2014; 111:7090-5. [PMID: 24778222 DOI: 10.1073/pnas.1321942111] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cellular senescence restricts the proliferative capacity of cells and is accompanied by the production of several proteins, collectively termed the "senescence-messaging secretome" (SMS). As senescent cells accumulate in tissue, local effects of the SMS have been hypothesized to disrupt tissue regenerative capacity. Klotho functions as an aging-suppressor gene, and Klotho-deficient (kl/kl) mice exhibit an accelerated aging-like phenotype that includes a truncated lifespan, arteriosclerosis, and emphysema. Because plasminogen activator inhibitor-1 (PAI-1), a serine protease inhibitor (SERPIN), is elevated in kl/kl mice and is a critical determinant of replicative senescence in vitro, we hypothesized that a reduction in extracellular proteolytic activity contributes to the accelerated aging-like phenotype of kl/kl mice. Here we show that PAI-1 deficiency retards the development of senescence and protects organ structure and function while prolonging the lifespan of kl/kl mice. These findings indicate that a SERPIN-regulated cell-nonautonomous proteolytic cascade is a critical determinant of senescence in vivo.
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Andrukhova O, Slavic S, Smorodchenko A, Zeitz U, Shalhoub V, Lanske B, Pohl EE, Erben RG. FGF23 regulates renal sodium handling and blood pressure. EMBO Mol Med 2014; 6:744-59. [PMID: 24797667 PMCID: PMC4203353 DOI: 10.1002/emmm.201303716] [Citation(s) in RCA: 239] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Fibroblast growth factor-23 (FGF23) is a bone-derived hormone regulating renal phosphate reabsorption and vitamin D synthesis in renal proximal tubules. Here, we show that FGF23 directly regulates the membrane abundance of the Na(+):Cl(-) co-transporter NCC in distal renal tubules by a signaling mechanism involving the FGF receptor/αKlotho complex, extracellular signal-regulated kinase 1/2 (ERK1/2), serum/glucocorticoid-regulated kinase 1 (SGK1), and with-no lysine kinase-4 (WNK4). Renal sodium (Na(+)) reabsorption and distal tubular membrane expression of NCC are reduced in mouse models of Fgf23 and αKlotho deficiency. Conversely, gain of FGF23 function by injection of wild-type mice with recombinant FGF23 or by elevated circulating levels of endogenous Fgf23 in Hyp mice increases distal tubular Na(+) uptake and membrane abundance of NCC, leading to volume expansion, hypertension, and heart hypertrophy in a αKlotho and dietary Na(+)-dependent fashion. The NCC inhibitor chlorothiazide abrogates FGF23-induced volume expansion and heart hypertrophy. Our findings suggest that FGF23 is a key regulator of renal Na(+) reabsorption and plasma volume, and may explain the association of FGF23 with cardiovascular risk in chronic kidney disease patients.
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Affiliation(s)
| | | | | | - Ute Zeitz
- University of Veterinary Medicine Vienna, Vienna, Austria
| | | | - Beate Lanske
- Harvard School of Dental Medicine, Boston, MA, USA
| | - Elena E Pohl
- University of Veterinary Medicine Vienna, Vienna, Austria
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Andrukhova O, Smorodchenko A, Egerbacher M, Streicher C, Zeitz U, Goetz R, Shalhoub V, Mohammadi M, Pohl EE, Lanske B, Erben RG. FGF23 promotes renal calcium reabsorption through the TRPV5 channel. EMBO J 2014; 33:229-46. [PMID: 24434184 PMCID: PMC3983685 DOI: 10.1002/embj.201284188] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
αKlotho is thought to activate the epithelial calcium channel Transient Receptor Potential Vanilloid-5 (TRPV5) in distal renal tubules through its putative glucuronidase/sialidase activity, thereby preventing renal calcium loss. However, αKlotho also functions as the obligatory co-receptor for fibroblast growth factor-23 (FGF23), a bone-derived phosphaturic hormone. Here, we show that renal calcium reabsorption and renal membrane abundance of TRPV5 are reduced in Fgf23 knockout mice, similar to what is seen in αKlotho knockout mice. We further demonstrate that αKlotho neither co-localizes with TRPV5 nor is regulated by FGF23. Rather, apical membrane abundance of TRPV5 in renal distal tubules and thus renal calcium reabsorption are regulated by FGF23, which binds the FGF receptor-αKlotho complex and activates a signaling cascade involving ERK1/2, SGK1, and WNK4. Our data thereby identify FGF23, not αKlotho, as a calcium-conserving hormone in the kidney.
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38
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Tomaschitz A, Ritz E, Pieske B, Rus-Machan J, Kienreich K, Verheyen N, Gaksch M, Grübler M, Fahrleitner-Pammer A, Mrak P, Toplak H, Kraigher-Krainer E, März W, Pilz S. Aldosterone and parathyroid hormone interactions as mediators of metabolic and cardiovascular disease. Metabolism 2014; 63:20-31. [PMID: 24095631 DOI: 10.1016/j.metabol.2013.08.016] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 08/26/2013] [Accepted: 08/28/2013] [Indexed: 01/09/2023]
Abstract
Inappropriate aldosterone and parathyroid hormone (PTH) secretion is strongly linked with development and progression of cardiovascular (CV) disease. Accumulating evidence suggests a bidirectional interplay between parathyroid hormone and aldosterone. This interaction may lead to a disproportionally increased risk of CV damage, metabolic and bone diseases. This review focuses on mechanisms underlying the mutual interplay between aldosterone and PTH as well as their potential impact on CV, metabolic and bone health. PTH stimulates aldosterone secretion by increasing the calcium concentration in the cells of the adrenal zona glomerulosa as a result of binding to the PTH/PTH-rP receptor and indirectly by potentiating angiotensin 2 induced effects. This may explain why after parathyroidectomy lower aldosterone levels are seen in parallel with improved cardiovascular outcomes. Aldosterone mediated effects are inappropriately pronounced in conditions such as chronic heart failure, excess dietary salt intake (relative aldosterone excess) and primary aldosteronism. PTH is increased as a result of (1) the MR (mineralocorticoid receptor) mediated calciuretic and magnesiuretic effects with a trend of hypocalcemia and hypomagnesemia; the resulting secondary hyperparathyroidism causes myocardial fibrosis and disturbed bone metabolism; and (2) direct effects of aldosterone on parathyroid cells via binding to the MR. This adverse sequence is interrupted by mineralocorticoid receptor blockade and adrenalectomy. Hyperaldosteronism due to klotho deficiency results in vascular calcification, which can be mitigated by spironolactone treatment. In view of the documented reciprocal interaction between aldosterone and PTH as well as the potentially ensuing target organ damage, studies are needed to evaluate diagnostic and therapeutic strategies to address this increasingly recognized pathophysiological phenomenon.
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Affiliation(s)
- Andreas Tomaschitz
- Department of Cardiology, Medical University of Graz, Graz, Austria; Specialist Clinic for Rehabilitation PV Bad Aussee, Bad Aussee, Austria.
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Lucisano S, Buemi M, Passantino A, Aloisi C, Cernaro V, Santoro D. New Insights on the Role of Vitamin D in the Progression of Renal Damage. Kidney Blood Press Res 2013; 37:667-78. [DOI: 10.1159/000355747] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2013] [Indexed: 11/19/2022] Open
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40
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Ritz E, Tomaschitz A. Aldosterone and the kidney: a rapidly moving frontier (an update). Nephrol Dial Transplant 2013; 29:2012-9. [PMID: 24194611 DOI: 10.1093/ndt/gft035] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Beyond the classical effect of aldosterone on sodium reabsorption in the distal nephron, the spectrum of aldosterone-induced effects on the kidney (and the cardiovascular system) continues to expand at a rapid pace. Blockade of this system has become an attractive target for intervention. Major contributions have been reported in the past 2-3 years. By necessity this brief summary addresses only some of the emerging issues of nephrological relevance. In this fast moving field, we try to give a concise discussion of papers with potential nephrological relevance in the past 2-3 years.
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Affiliation(s)
- Eberhard Ritz
- Nierenzentrum, Im Neuenheimer Feld 162, Heidelberg, Germany
| | - Andreas Tomaschitz
- Department of Cardiology, Medical University Graz, Graz, Austria Specialist Clinic for Rehabilitation PV Bad Aussee, Bad Aussee, Austria
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41
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Brown JM, Williams JS, Luther JM, Garg R, Garza AE, Pojoga LH, Ruan DT, Williams GH, Adler GK, Vaidya A. Human interventions to characterize novel relationships between the renin-angiotensin-aldosterone system and parathyroid hormone. Hypertension 2013; 63:273-80. [PMID: 24191286 DOI: 10.1161/hypertensionaha.113.01910] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Observational studies in primary hyperaldosteronism suggest a positive relationship between aldosterone and parathyroid hormone (PTH); however, interventions to better characterize the physiological relationship between the renin-angiotensin-aldosterone system (RAAS) and PTH are needed. We evaluated the effect of individual RAAS components on PTH using 4 interventions in humans without primary hyperaldosteronism. PTH was measured before and after study (1) low-dose angiotensin II (Ang II) infusion (1 ng/kg per minute) and captopril administration (25 mg×1); study (2) high-dose Ang II infusion (3 ng/kg per minute); study (3) blinded crossover randomization to aldosterone infusion (0.7 µg/kg per hour) and vehicle; and study (4) blinded randomization to spironolactone (50 mg/daily) or placebo for 6 weeks. Infusion of Ang II at 1 ng/kg per minute acutely increased aldosterone (+148%) and PTH (+10.3%), whereas Ang II at 3 ng/kg per minute induced larger incremental changes in aldosterone (+241%) and PTH (+36%; P<0.01). Captopril acutely decreased aldosterone (-12%) and PTH (-9.7%; P<0.01). In contrast, aldosterone infusion robustly raised serum aldosterone (+892%) without modifying PTH. However, spironolactone therapy during 6 weeks modestly lowered PTH when compared with placebo (P<0.05). In vitro studies revealed the presence of Ang II type I and mineralocorticoid receptor mRNA and protein expression in normal and adenomatous human parathyroid tissues. We observed novel pleiotropic relationships between RAAS components and the regulation of PTH in individuals without primary hyperaldosteronism: the acute modulation of PTH by the RAAS seems to be mediated by Ang II, whereas the long-term influence of the RAAS on PTH may involve aldosterone. Future studies to evaluate the impact of RAAS inhibitors in treating PTH-mediated disorders are warranted.
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Affiliation(s)
- Jenifer M Brown
- Center for Adrenal Disorders, Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Ave, RFB, Boston, MA 02115.
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Shumilina E, Nurbaeva MK, Yang W, Schmid E, Szteyn K, Russo A, Heise N, Leibrock C, Xuan NT, Faggio C, Kuro-o M, Lang F. Altered regulation of cytosolic Ca²⁺ concentration in dendritic cells from klotho hypomorphic mice. Am J Physiol Cell Physiol 2013; 305:C70-7. [PMID: 23596175 DOI: 10.1152/ajpcell.00355.2012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The function of dendritic cells (DCs), antigen-presenting cells regulating naïve T-cells, is regulated by cytosolic Ca²⁺ concentration ([Ca²⁺]i). [Ca²⁺]i is increased by store-operated Ca²⁺ entry and decreased by K⁺-independent (NCX) and K⁺-dependent (NCKX) Na⁺/Ca²⁺ exchangers. NCKX exchangers are stimulated by immunosuppressive 1,25-dihydroxyvitamin D3 [1,25(OH)₂D₃], the biologically active form of vitamin D. Formation of 1,25(OH)₂D₃ is inhibited by the antiaging protein Klotho. Thus 1,25(OH)₂D₃ plasma levels are excessive in Klotho-deficient mice (klothohm). The present study explored whether Klotho deficiency modifies [Ca²⁺]i regulation in DCs. DCs were isolated from the bone marrow of klothohm mice and wild-type mice (klotho+/+) and cultured for 7-9 days with granulocyte-macrophage colony-stimulating factor. According to major histocompatibility complex II (MHC II) and CD86 expression, differentiation and lipopolysaccharide (LPS)-induced maturation were similar in klothohm DCs and klotho+/+ DCs. However, NCKX1 membrane abundance and NCX/NCKX-activity were significantly enhanced in klothohm DCs. The [Ca²⁺]i increase upon acute application of LPS (1 μg/ml) was significantly lower in klothohm DCs than in klotho+/+ DCs, a difference reversed by the NCKX blocker 3',4'-dichlorobenzamyl (DBZ; 10 μM). CCL21-dependent migration was significantly less in klothohm DCs than in klotho+/+ DCs but could be restored by DBZ. NCKX activity was enhanced by pretreatment of klotho+/+ DC precursors with 1,25(OH)₂D₃ the first 2 days after isolation from bone marrow. Feeding klothohm mice a vitamin D-deficient diet decreased NCKX activity, augmented LPS-induced increase of [Ca²⁺]i, and enhanced migration of klothohm DCs, thus dissipating the differences between klothohm DCs and klotho+/+ DCs. In conclusion, Klotho deficiency upregulates NCKX1 membrane abundance and Na⁺/Ca²⁺-exchange activity, thus blunting the increase of [Ca²⁺]i following LPS exposure and CCL21-mediated migration. The effects are in large part due to excessive 1,25(OH)₂D₃ formation.
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Lang F, Ritz E, Voelkl J, Alesutan I. Vascular calcification--is aldosterone a culprit? Nephrol Dial Transplant 2013; 28:1080-4. [PMID: 23476041 DOI: 10.1093/ndt/gft041] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
In chronic kidney disease (CKD), increased plasma phosphate concentrations cause vascular calcification which substantially contribute to cardiovascular events and increased mortality of CKD patients. Similar to CKD patients, klotho-hypomorphic mice (kl/kl) also suffer from excessive vascular calcification leading to growth deficit, rapid ageing and early death. The hyperphosphataemia of kl/kl mice results from excessive formation of 1,25(OH)2D3 causing excessive intestinal phosphate absorption. Further, kl/kl mice further suffer from hyperaldosteronism and compelling evidence points to an active role of mineralocorticoids in triggering osteoinductive programmes in the vasculature, thus further contributing to the development of vascular calcification. Conversely, in kl/kl mice, the mineralocorticoid receptor antagonist spironolactone decreased the vascular osteoinductive processes and reversed the excessive expression of osteogenic programmes, i.e. type III sodium-dependent phosphate transporter Pit1, tumour necrosis factor α (Tnfα), transcription factors Msx2, Cbfa1/Runx2 and osterix as well as alkaline phosphatase (Alp). In human aortic vascular smooth muscle cells (HAoSMCs), aldosterone alone similarly triggered an 'osteogenic' programme, thus increasing PIT1, TNFα, MSX2, CBFA1/RUNX2 and ALP expression as well as ALP activity and potentiated the effects of phosphate treatment. These effects were again reversed by spironolactone and in addition by PIT1 silencing. The above observations reveal that the severe vascular calcification is not only the result of high plasma phosphate concentrations, but also promoted by aldosterone-driven osteoinductive signalling. Future studies in CKD patients will be required to define the role of aldosterone and the potential impact of its inhibition by spironolactone in the pathophysiology of vascular calcification.
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Affiliation(s)
- Florian Lang
- Department of Physiology, University of Tübingen, Tübingen, Germany.
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Voelkl J, Alesutan I, Leibrock CB, Quintanilla-Martinez L, Kuhn V, Feger M, Mia S, Ahmed MSE, Rosenblatt KP, Kuro-O M, Lang F. Spironolactone ameliorates PIT1-dependent vascular osteoinduction in klotho-hypomorphic mice. J Clin Invest 2013; 123:812-22. [PMID: 23298834 DOI: 10.1172/jci64093] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 11/01/2012] [Indexed: 12/21/2022] Open
Abstract
Klotho is a potent regulator of 1,25-hydroxyvitamin D3 [1,25(OH)2D3] formation and calcium-phosphate metabolism. Klotho-hypomorphic mice (kl/kl mice) suffer from severe growth deficits, rapid aging, hyperphosphatemia, hyperaldosteronism, and extensive vascular and soft tissue calcification. Sequelae of klotho deficiency are similar to those of end-stage renal disease. We show here that the mineralocorticoid receptor antagonist spironolactone reduced vascular and soft tissue calcification and increased the life span of kl/kl mice, without significant effects on 1,25(OH)2D3, FGF23, calcium, and phosphate plasma concentrations. Spironolactone also reduced the expression of osteoinductive Pit1 and Tnfa mRNA, osteogenic transcription factors, and alkaline phosphatase (Alpl) in calcified tissues of kl/kl mice. In human aortic smooth muscle cells (HAoSMCs), aldosterone dose-dependently increased PIT1 mRNA expression, an effect paralleled by increased expression of osteogenic transcription factors and enhanced ALP activity. The effects of aldosterone were reversed by both spironolactone treatment and PIT1 silencing and were mitigated by FGF23 cotreatment in HAoSMCs. In conclusion, aldosterone contributes to vascular and soft tissue calcification, an effect due, at least in part, to stimulation of spironolactone-sensitive, PIT1-dependent osteoinductive signaling.
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Affiliation(s)
- Jakob Voelkl
- Department of Physiology, University of Tübingen, Tübingen, Germany
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45
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Vanholder R. The ultimate salt war? Uraemic toxins are all that count in dialysis patients. Nephrol Dial Transplant 2012; 27:62-6. [DOI: 10.1093/ndt/gfr637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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46
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de Borst MH, Vervloet MG, ter Wee PM, Navis G. Cross talk between the renin-angiotensin-aldosterone system and vitamin D-FGF-23-klotho in chronic kidney disease. J Am Soc Nephrol 2011; 22:1603-9. [PMID: 21852584 PMCID: PMC3171931 DOI: 10.1681/asn.2010121251] [Citation(s) in RCA: 202] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
There is increasingly evidence that the interactions between vitamin D, fibroblast growth factor 23 (FGF-23), and klotho form an endocrine axis for calcium and phosphate metabolism, and derangement of this axis contributes to the progression of renal disease. Several recent studies also demonstrate negative regulation of the renin gene by vitamin D. In chronic kidney disease (CKD), low levels of calcitriol, due to the loss of 1-alpha hydroxylase, increase renal renin production. Activation of the renin-angiotensin-aldosterone system (RAAS), in turn, reduces renal expression of klotho, a crucial factor for proper FGF-23 signaling. The resulting high FGF-23 levels suppress 1-alpha hydroxylase, further lowering calcitriol. This feedback loop results in vitamin D deficiency, RAAS activation, high FGF-23 levels, and renal klotho deficiency, all of which associate with progression of renal damage. Here we examine current evidence for an interaction between the RAAS and the vitamin D-FGF-23-klotho axis as well as its possible implications for progression of CKD.
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Affiliation(s)
- Martin H de Borst
- Department of Internal Medicine, Division of Nephrology, University Medical Center Groningen and University of Groningen, P.O. Box 30.001, 9700 RB Groningen, The Netherlands.
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Dërmaku-Sopjani M, Sopjani M, Saxena A, Shojaiefard M, Bogatikov E, Alesutan I, Eichenmüller M, Lang F. Downregulation of NaPi-IIa and NaPi-IIb Na-coupled phosphate transporters by coexpression of Klotho. Cell Physiol Biochem 2011; 28:251-8. [PMID: 21865732 DOI: 10.1159/000331737] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2011] [Indexed: 12/25/2022] Open
Abstract
Klotho, a transmembrane protein, protease and hormone has been shown to exert a profound effect on phosphate metabolism. Klotho overexpression lowers and Klotho deficiency increases the plasma phosphate concentration, effects in part attributed to an inhibitory effect of Klotho on the formation of 1,25-dihydroxycholecalciferol (1,25(OH) (2)D(3)), the active form of Vitamin D. Beyond that Klotho has been shown to decrease renal tubular phosphate transport more directly. The influence of Klotho on the plasma phosphate concentration contributes to the profound effect of Klotho on ageing and life span. The present study explored whether Klotho influences the major renal tubular (NaPi-IIa) and the major intestinal (NaPi-IIb) phosphate transporters. For functional analysis NaPi-IIa or NaPi-IIb were expressed in Xenopus oocytes both, without or with additional coexpression of Klotho and electrogenic phosphate transport was estimated from the phosphate-induced current (Ip). According to RT-PCR Klotho is expressed in the murine kidney and intestine. Coexpression of Klotho decreased Ip in both NaPi-IIa- and NaPi-IIb-expressing oocytes. Klotho decreased the maximal Ip without appreciably affecting the concentration required for halfmaximal Ip. Treatment of NaPi-IIa- or NaPi-IIb-expressing oocytes with Klotho protein similarly decreased Ip. In conclusion, Klotho down regulates both, renal (NaPi-IIa) and intestinal (NaPi-IIb) phosphate transporters.
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Zacchia M, Capasso G. Dehydration: a new modulator of klotho expression. Am J Physiol Renal Physiol 2011; 301:F743-4. [PMID: 21835769 DOI: 10.1152/ajprenal.00412.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Tang C, Pathare G, Michael D, Fajol A, Eichenmüller M, Lang F. Downregulation of Klotho expression by dehydration. Am J Physiol Renal Physiol 2011; 301:F745-50. [PMID: 21734097 DOI: 10.1152/ajprenal.00037.2011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Klotho, a transmembrane protein, protease, and hormone mainly expressed in renal tissue counteracts aging. Overexpression of Klotho substantially prolongs the life span. Klotho deficiency leads to excessive formation of 1,25(OH)(2)D(3), growth deficit, accelerated aging, and early death. Aging is frequently paralleled by dehydration, which is considered to accelerate the development of age-related disorders. The present study explored the possibility that dehydration influences Klotho expression. Klotho transcript levels were determined by RT-PCR, and Klotho protein abundance was detected by Western blotting in renal tissue from hydrated and 36-h-dehydrated mice as well as in human embryonic kidney (HEK293) cells. Dehydration was followed by a significant decline of renal Klotho transcript levels and protein abundance, accompanied by an increase in plasma osmolarity as well as plasma ADH, aldosterone, and 1,25(OH)(2)D(3) levels. Antidiuretic hormone (ADH; 50 nM) and aldosterone (1 μM) significantly decreased Klotho transcription and protein expression in HEK293 cells. In conclusion, the present observations disclose a powerful effect of dehydration on Klotho expression, an effect at least partially mediated by enhanced release of ADH and aldosterone.
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Bacchetta J, Cochat P, Salusky IB. [FGF23 and Klotho: the new cornerstones of phosphate/calcium metabolism]. Arch Pediatr 2011; 18:686-95. [PMID: 21497493 PMCID: PMC4292917 DOI: 10.1016/j.arcped.2011.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 01/21/2011] [Accepted: 03/08/2011] [Indexed: 12/18/2022]
Abstract
Since its first description as a phosphaturic agent in the early 2000s, fibroblast growth factor 23 (FGF23) has rapidly become the third key player of phosphate/calcium metabolism after PTH and vitamin D. FGF23 is a protein synthesized by osteocytes that acts mainly as a phosphaturic factor and a suppressor of 1α hydroxylase activity in the kidney. It inhibits the expression of type IIa and IIc sodium-phosphate cotransporters on the apical membrane of proximal tubular cells, thus leading to inhibition of phosphate reabsorption. Moreover, it also inhibits 1α hydroxylase activity. These two renal pathways account together for the hypophosphatemic effect of FGF23, but FGF23 has also been recently described as an inhibiting factor for PTH synthesis. Its exact role in bone remains to be defined. A transmembrane protein, Klotho, is an essential cofactor for FGF23 biological activity, but it can also act by itself for calcium and PTH regulation. This paper gives an overview of these recent data of phosphate/calcium physiology, as well as a description of clinical conditions associated with FGF23 deregulation (genetic diseases and chronic kidney disease). As a conclusion, future therapeutic consequences of the FGF23/Klotho axis are discussed.
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Affiliation(s)
- J Bacchetta
- Centre de référence des maladies rénales rares, hôpital Femme-Mère-Enfant, boulevard Pinel, 69677 Bron cedex, France
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