1
|
Martínez-Heredia L, Canelo-Moreno JM, García-Fontana B, Muñoz-Torres M. Non-Classical Effects of FGF23: Molecular and Clinical Features. Int J Mol Sci 2024; 25:4875. [PMID: 38732094 PMCID: PMC11084844 DOI: 10.3390/ijms25094875] [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: 04/08/2024] [Revised: 04/21/2024] [Accepted: 04/26/2024] [Indexed: 05/13/2024] Open
Abstract
This article reviews the role of fibroblast growth factor 23 (FGF23) protein in phosphate metabolism, highlighting its regulation of vitamin D, parathyroid hormone, and bone metabolism. Although it was traditionally thought that phosphate-calcium homeostasis was controlled exclusively by parathyroid hormone (PTH) and calcitriol, pathophysiological studies revealed the influence of FGF23. This protein, expressed mainly in bone, inhibits the renal reabsorption of phosphate and calcitriol formation, mediated by the α-klotho co-receptor. In addition to its role in phosphate metabolism, FGF23 exhibits pleiotropic effects in non-renal systems such as the cardiovascular, immune, and metabolic systems, including the regulation of gene expression and cardiac fibrosis. Although it has been proposed as a biomarker and therapeutic target, the inhibition of FGF23 poses challenges due to its potential side effects. However, the approval of drugs such as burosumab represents a milestone in the treatment of FGF23-related diseases.
Collapse
Affiliation(s)
- Luis Martínez-Heredia
- Instituto de Investigación Biosanitaria de Granada, 18014 Granada, Spain;
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | | | - Beatriz García-Fontana
- Instituto de Investigación Biosanitaria de Granada, 18014 Granada, Spain;
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, 18016 Granada, Spain
- Department of Cell Biology, University of Granada, 18016 Granada, Spain
| | - Manuel Muñoz-Torres
- Instituto de Investigación Biosanitaria de Granada, 18014 Granada, Spain;
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, 18016 Granada, Spain
- Department of Medicine, University of Granada, 18016 Granada, Spain
| |
Collapse
|
2
|
Rivoira MA, Peralta López ME, Areco V, Díaz de Barboza G, Dionisi MP, Tolosa de Talamoni N. Emerging concepts on the FGF23 regulation and activity. Mol Cell Biochem 2024:10.1007/s11010-024-04982-6. [PMID: 38581553 DOI: 10.1007/s11010-024-04982-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 02/28/2024] [Indexed: 04/08/2024]
Abstract
Fibroblast growth factor 23 (FGF23) discovery has provided new insights into the regulation of Pi and Ca homeostasis. It is secreted by osteoblasts and osteocytes, and acts mainly in the kidney, parathyroid, heart, and bone. The aim of this review is to highlight the current knowledge on the factors modulating the synthesis of FGF23, the canonical and non-canonical signaling pathways of the hormone, the role of FGF23 in different pathophysiological conditions, and the anti-FGF23 therapy. This is a narrative review based on the search of PubMed database in the range of years 2000-2023 using the keywords local and systemic regulators of FGF23 synthesis, FGF23 receptors, canonical and non-canonical pathways, pathophysiological conditions and FGF23, and anti-FGF23 therapy, focusing the data on the molecular mechanisms. The regulation of FGF23 synthesis is complex and multifactorial. It is regulated by local factors and systemic regulators mainly involved in bone mineralization. The excessive FGF23 production is associated with different congenital diseases and with diseases occurring with a secondary high FGF23 production such as in chronic disease kidney and tumor-induced osteomalacia (TIO). The anti-FGF23 therapy appears to be useful to treat chromosome X-linked hypophosphatemia and TIO, but there are doubts about the handle of excessive FGF23 production in CKD. FGF23 biochemistry and pathophysiology are generating a plethora of knowledge to reduce FGF23 bioactivity at many levels that might be useful for future therapeutics of diseases associated with high-serum FGF23 levels.
Collapse
Affiliation(s)
- María Angélica Rivoira
- Laboratorio "Dr. Fernando Cañas", Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Pabellón Argentina, 2do, Piso, Ciudad Universitaria, 5000, Córdoba, Argentina
| | - María Elena Peralta López
- Laboratorio "Dr. Fernando Cañas", Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Pabellón Argentina, 2do, Piso, Ciudad Universitaria, 5000, Córdoba, Argentina
| | - Vanessa Areco
- Laboratorio "Dr. Fernando Cañas", Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Pabellón Argentina, 2do, Piso, Ciudad Universitaria, 5000, Córdoba, Argentina
- Instituto Multidisciplinario de Investigación y Transferencia Agroalimentaria y Biotecnológica (IMITAB, CONICET-UNVM), Córdoba, Argentina
| | - Gabriela Díaz de Barboza
- Laboratorio "Dr. Fernando Cañas", Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Pabellón Argentina, 2do, Piso, Ciudad Universitaria, 5000, Córdoba, Argentina
| | - María Paula Dionisi
- Cátedra de Clínica Médica II - UHMI Nº 2, Hospital San Roque, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Nori Tolosa de Talamoni
- Laboratorio "Dr. Fernando Cañas", Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Pabellón Argentina, 2do, Piso, Ciudad Universitaria, 5000, Córdoba, Argentina.
| |
Collapse
|
3
|
Hamid AK, Pastor Arroyo EM, Calvet C, Hewitson TD, Muscalu ML, Schnitzbauer U, Smith ER, Wagner CA, Egli-Spichtig D. Phosphate Restriction Prevents Metabolic Acidosis and Curbs Rise in FGF23 and Mortality in Murine Folic Acid-Induced AKI. J Am Soc Nephrol 2024; 35:261-280. [PMID: 38189228 PMCID: PMC10914210 DOI: 10.1681/asn.0000000000000291] [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: 08/14/2023] [Accepted: 12/02/2023] [Indexed: 01/09/2024] Open
Abstract
SIGNIFICANCE STATEMENT Patients with AKI suffer a staggering mortality rate of approximately 30%. Fibroblast growth factor 23 (FGF23) and phosphate (P i ) rise rapidly after the onset of AKI and have both been independently associated with ensuing morbidity and mortality. This study demonstrates that dietary P i restriction markedly diminished the early rise in plasma FGF23 and prevented the rise in plasma P i , parathyroid hormone, and calcitriol in mice with folic acid-induced AKI (FA-AKI). Furthermore, the study provides evidence for P i -sensitive osseous Fgf23 mRNA expression and reveals that P i restriction mitigated calciprotein particles (CPPs) formation, inflammation, acidosis, cardiac electrical disturbances, and mortality in mice with FA-AKI. These findings suggest that P i restriction may have a prophylactic potential in patients at risk for AKI. BACKGROUND In AKI, plasma FGF23 and P i rise rapidly and are independently associated with disease severity and outcome. METHODS The effects of normal (NP) and low (LP) dietary P i were investigated in mice with FA-AKI after 3, 24, and 48 hours and 14 days. RESULTS After 24 hours of AKI, the LP diet curbed the rise in plasma FGF23 and prevented that of parathyroid hormone and calcitriol as well as of osseous but not splenic or thymic Fgf23 mRNA expression. The absence of Pth prevented the rise in calcitriol and reduced the elevation of FGF23 in FA-AKI with the NP diet. Furthermore, the LP diet attenuated the rise in renal and plasma IL-6 and mitigated the decline in renal α -Klotho. After 48 hours, the LP diet further dampened renal IL-6 expression and resulted in lower urinary neutrophil gelatinase-associated lipocalin. In addition, the LP diet prevented the increased formation of CPPs. Fourteen days after AKI induction, the LP diet group maintained less elevated plasma FGF23 levels and had greater survival than the NP diet group. This was associated with prevention of metabolic acidosis, hypocalcemia, hyperkalemia, and cardiac electrical disturbances. CONCLUSIONS This study reveals P i -sensitive FGF23 expression in the bone but not in the thymus or spleen in FA-AKI and demonstrates that P i restriction mitigates CPP formation, inflammation, acidosis, and mortality in this model. These results suggest that dietary P i restriction could have prophylactic potential in patients at risk for AKI.
Collapse
Affiliation(s)
- Ahmad Kamal Hamid
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
| | - Eva Maria Pastor Arroyo
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
| | - Charlotte Calvet
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Zurich Integrative Rodent Physiology (ZIRP), University of Zurich, Zurich, Switzerland
| | - Timothy D. Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Australia
- Department of Medicine, University of Melbourne, Melbourne Australia
| | - Maria Lavinia Muscalu
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
| | - Udo Schnitzbauer
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Edward R. Smith
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Australia
- Department of Medicine, University of Melbourne, Melbourne Australia
| | - Carsten Alexander Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
| | - Daniela Egli-Spichtig
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
| |
Collapse
|
4
|
Hamid AK, Pastor Arroyo EM, Lee SS, Wagner CA, Egli-Spichtig D. A novel method for automated crystal visualization and quantification in murine folic acid-induced acute kidney injury. Am J Physiol Renal Physiol 2024; 326:F105-F117. [PMID: 37881875 PMCID: PMC11194050 DOI: 10.1152/ajprenal.00140.2023] [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: 05/23/2023] [Revised: 09/14/2023] [Accepted: 10/06/2023] [Indexed: 10/27/2023] Open
Abstract
Folic acid (FA)-induced acute kidney injury (FA-AKI) is an increasingly prevalent rodent disease model involving the injection of a high dose of FA that culminates in renal FA crystal deposition and injury. However, the literature characterizing the FA-AKI model is sparse and dated in part due to the absence of a well-described methodology for the visualization and quantification of renal FA crystals. Using widely available materials and tools, we developed a straightforward and crystal-preserving histological protocol that can be coupled with automated imaging for renal FA crystal visualization and generated an automated macro for downstream crystal content quantification. The applicability of the method was demonstrated by characterizing the model in male and female C57BL6/JRj mice after 3 and 30 h of FA treatment. Kidneys from both sexes and timepoints showed a bimodal distribution of FA crystal deposition in the cortical and medullary regions while, compared with males, females exhibited higher renal FA crystal content at the 30-h timepoint accompanied by greater kidney weight and higher plasma urea. Despite comparable plasma phosphate concentrations, FA-AKI resulted in a substantially more elevated plasma intact fibroblast growth factor 23 (FGF23) in females, reflected by a similar pattern in osseous Fgf23 mRNA expression. Therefore, the presented method constitutes a valuable tool for the quantification of renal FA crystals, which can aid the mechanistic characterization of the FA-AKI model and serves as a means to control for confounding changes in FA crystallization when using the model for investigating early and prophylactic AKI therapeutic interventions.NEW & NOTEWORTHY Here, we describe a novel method for the visualization and quantification of renal folic acid (FA) crystals in the rodent FA-induced acute kidney injury (FA-AKI) model. The protocol involves a straightforward histological approach followed by fully automated imaging and quantification steps. Applicability was confirmed by showing that the FA-AKI model is sex-dependent. The method can serve as a tool to aid in characterizing FA-AKI and to control for studies investigating prophylactic therapeutic avenues using FA-AKI.
Collapse
Affiliation(s)
- Ahmad Kamal Hamid
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Eva Maria Pastor Arroyo
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Sung Sik Lee
- Scientific Center for Optical and Electron Microscopy, ETH Zurich, Zurich, Switzerland
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Carsten Alexander Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - Daniela Egli-Spichtig
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| |
Collapse
|
5
|
Rostamzadeh F, Moosavi-Saeed Y, Yeganeh-Hajahmadi M. Interaction of Klotho and sirtuins. Exp Gerontol 2023; 182:112306. [PMID: 37804921 DOI: 10.1016/j.exger.2023.112306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 09/30/2023] [Accepted: 10/02/2023] [Indexed: 10/09/2023]
Abstract
OBJECTIVE In this article, we review the articles that have reported the interaction between Klotho and sirtuins. RECENT FINDINGS Sirtuins are a family of histone deacetylase enzymes that are considered to be the main regulators of biological processes. This family is one of the essential factors for postponing aging and increasing the life span of organisms. Sirtuins play a role in regulating the function of various cellular processes such as cellular metabolism, oxidative stress, apoptosis, and inflammation. It has also been shown that various diseases are related to these enzymes. Klotho is an anti-aging protein that exists as a membrane protein as well as a soluble circulating form. The membrane type of this protein acts as a co-receptor of the FGF endocrine family. It has been shown that the Klotho gene is related to age-related diseases, including osteoporosis, coronary artery, brain diseases, diabetes, etc. At the same time, it is difficult to separate the actions of Klotho and endocrine FGFs. Several studies have shown that Klotho and sirtuins interact with each other at different regulatory levels. However, it is necessary to carry out more in-vivo investigations to create new windows towards the treatment or prevention of various diseases.
Collapse
Affiliation(s)
- Farzaneh Rostamzadeh
- Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran
| | - Yasamin Moosavi-Saeed
- Endocrinology and Metabolism Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman University of Medical Sciences, Kerman, Iran
| | - Mahboobeh Yeganeh-Hajahmadi
- Cardiovascular Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman University of Medical Science, Kerman, Iran.
| |
Collapse
|
6
|
Egli-Spichtig D, Hamid AK, Arroyo EMP, Ketteler M, Wiecek A, Rosenkranz AR, Pasch A, Lorenz H, Hellmann B, Karus M, Ammer R, Rubio-Aliaga I, Wagner CA. Intact FGF23 predicts serum phosphate improvement after combined nicotinamide and phosphate binder treatment in hemodialysis patients. Clin Kidney J 2023; 16:1622-1633. [PMID: 37779856 PMCID: PMC10539220 DOI: 10.1093/ckj/sfad040] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Indexed: 10/03/2023] Open
Abstract
Background Hyperphosphatemia is associated with increased mortality and cardiovascular morbidity of end-stage kidney failure (ESKF) patients. Managing serum phosphate in ESKF patients is challenging and mostly based on limiting intestinal phosphate absorption with low phosphate diets and phosphate binders (PB). In a multi-centric, double-blinded, placebo-controlled study cohort of maintenance hemodialysis patients with hyperphosphatemia, we demonstrated the efficacy of nicotinamide modified release (NAMR) formulation treatment in addition to standard PB therapy in decreasing serum phosphate. Here we aimed to assess the relationship between phosphate, FGF23, inflammation and iron metabolism in this cohort. Methods We measured the plasma concentrations of intact fibroblast growth factor 23 (iFGF23) and selected proinflammatory cytokines at baseline and Week 12 after initiating treatment. Results We observed a strong correlation between iFGF23 and cFGF23 (C-terminal fragment plus iFGF23). We identified iFGF23 as a better predictor of changes in serum phosphate induced by NAMR and PB treatment compared with cFGF23. Recursive partitioning revealed at baseline and Week 12, that iFGF23 and cFGF23 together with T50 propensity were the most important predictors of serum phosphate, whereas intact parathyroid hormone (iPTH) played a minor role in this model. Furthermore, we found serum phosphate and iPTH as the best predictors of iFGF23 and cFGF23. Sex, age, body mass index, and markers of inflammation and iron metabolism had only a minor impact in predicting FGF23. Conclusion Lowering serum phosphate in ESKF patients may depend highly on iFGF23 which is correlated to cFGF23 levels. Serum phosphate was the most important predictor of plasma FGF23 in this ESKF cohort.
Collapse
Affiliation(s)
- Daniela Egli-Spichtig
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Ahmad Kamal Hamid
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Eva Maria Pastor Arroyo
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Markus Ketteler
- Robert Bosch Hospital, Department of General Internal Medicine and Nephrology, Stuttgart, Germany
| | - Andrzej Wiecek
- Department of Nephrology, Transplantation and Internal Medicine, Medical University of Silesia, Katowice, Poland
| | - Alexander R Rosenkranz
- Division of Nephrology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - Andreas Pasch
- Calciscon AG, 2503 Biel, Switzerland
- Department of Nephrology, Lindenhofspital, 3012 Bern, Switzerland
- Department of Physiology and Pathophysiology, Johannes Kepler University Linz, Linz, Austria
| | - Horst Lorenz
- Buero fuer Biometrie und Statistik, Neuberg, Germany
| | | | - Michael Karus
- MEDICE Arzneimittel Pütter GmbH & Co KG, Iserlohn, Germany
| | - Richard Ammer
- MEDICE Arzneimittel Pütter GmbH & Co KG, Iserlohn, Germany
- Department of Medicine D, Division of General Internal Medicine, Nephrology and Rheumatology, University Hospital of Münster, Münster, Germany
| | - Isabel Rubio-Aliaga
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland, and National Center of Competence in Research NCCR Kidney.CH
| |
Collapse
|
7
|
Li X, Lozovatsky L, Tommasini SM, Fretz J, Finberg KE. Bone marrow sinusoidal endothelial cells are a site of Fgf23 upregulation in a mouse model of iron deficiency anemia. Blood Adv 2023; 7:5156-5171. [PMID: 37417950 PMCID: PMC10480544 DOI: 10.1182/bloodadvances.2022009524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 06/16/2023] [Accepted: 07/05/2023] [Indexed: 07/08/2023] Open
Abstract
Iron deficiency is a potent stimulator of fibroblast growth factor 23 (FGF23), a hormonal regulator of phosphate and vitamin D metabolism, that is classically thought to be produced by bone-embedded osteocytes. Here, we show that iron-deficient transmembrane serine protease 6 knockout (Tmprss6-/-) mice exhibit elevated circulating FGF23 and Fgf23 messenger RNA (mRNA) upregulation in the bone marrow (BM) but not the cortical bone. To clarify sites of Fgf23 promoter activity in Tmprss6-/- mice, we introduced a heterozygous enhanced green fluorescent protein (eGFP) reporter allele at the endogenous Fgf23 locus. Heterozygous Fgf23 disruption did not alter the severity of systemic iron deficiency or anemia in the Tmprss6-/- mice. Tmprss6-/-Fgf23+/eGFP mice showed green fluorescence in the vascular regions of BM sections and showed a subset of BM endothelial cells that were GFPbright by flow cytometry. Mining of transcriptomic data sets from mice with normal iron balance revealed higher Fgf23 mRNA in BM sinusoidal endothelial cells (BM-SECs) than that in other BM endothelial cell populations. Anti-GFP immunohistochemistry of fixed BM sections from Tmprss6-/-Fgf23+/eGFP mice revealed GFP expression in BM-SECs, which was more intense than in nonanemic controls. In addition, in mice with intact Tmprss6 alleles, Fgf23-eGFP reporter expression increased in BM-SECs following large-volume phlebotomy and also following erythropoietin treatment both ex vivo and in vivo. Collectively, our results identified BM-SECs as a novel site for Fgf23 upregulation in both acute and chronic anemia. Given the elevated serum erythropoietin in both anemic models, our findings raise the possibility that erythropoietin may act directly on BM-SECs to promote FGF23 production during anemia.
Collapse
Affiliation(s)
- Xiuqi Li
- Department of Pathology, Yale School of Medicine, New Haven, CT
| | | | - Steven M. Tommasini
- Department of Orthopaedics & Rehabilitation, Yale School of Medicine, New Haven, CT
| | - Jackie Fretz
- Department of Orthopaedics & Rehabilitation, Yale School of Medicine, New Haven, CT
| | | |
Collapse
|
8
|
Myrou A, Aslanidis T, Makedou K, Mitsianis A, Thisiadou A, Karalazou P, Chatzopoulos G, Papadopoulos A, Kalis A, Giagkoulis D, Lezgidis F, Savopoulos C. Fibroblast Growth Factor 23 in COVID-19: An Observational Study. Cureus 2023; 15:e42561. [PMID: 37637614 PMCID: PMC10460241 DOI: 10.7759/cureus.42561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2023] [Indexed: 08/29/2023] Open
Abstract
INTRODUCTION Fibroblast growth factor 23 (FGF23) belongs structurally to the endocrine FGF protein family, which also includes FGF19 and FGF21. In the past decade, FGF23 has emerged as a possible diagnostic, prognostic biomarker, and therapeutic target in several conditions. Data about COVID-19 and FGF23 is still limited, yet they suggest interesting interactions. OBJECTIVE In the present study, the levels of FGF23 were investigated in COVID-19 patients. These levels were also correlated with other inflammatory markers. MATERIALS AND METHODS In our prospective observational study, blood samples were collected from 81 patients admitted with COVID-19 (31 males and 50 females). We analyzed the relation of serum FGF23 levels with biochemistry, total blood count, coagulation parameters, and demographic data. RESULTS The distribution of FGF23 serum levels according to sex and age (n28-40=8, n41-60=28, n65-75= 25, n75+=20) was similar. No significant correlation between FGF23 and any other biochemistry, total blood count, and coagulation parameter was revealed in the whole sample. Nevertheless, there was a variation in the results among different age groups. CONCLUSION FGF23 levels seem to vary in symptomatic COVID-19 infection, but well-organized studies with larger numbers of patients in each group are needed to determine any reliable correlation between FGF23 and other laboratory parameters.
Collapse
Affiliation(s)
- Athena Myrou
- Department of Internal Medicine, American Hellenic Educational Progressive Association (AHEPA) University Hospital, Thessaloniki, GRC
| | - Theodoros Aslanidis
- Department of Intensive Care Unit, St. Paul Agios Pavlos General Hospital, Thessaloniki, GRC
| | - Keli Makedou
- Department of Biochemistry, American Hellenic Educational Progressive Association (AHEPA) University Hospital, Thessaloniki, GRC
| | - Athanasios Mitsianis
- Department of Internal Medicine, Mpodosakeio General Prefecture Hospital, Ptolemaida, GRC
| | - Aikaterini Thisiadou
- Department of Internal Medicine, American Hellenic Educational Progressive Association (AHEPA) University Hospital, Thessaloniki, GRC
| | - Paraskevi Karalazou
- Department of Internal Medicine, American Hellenic Educational Progressive Association (AHEPA) University Hospital, Thessaloniki, GRC
| | - Georgios Chatzopoulos
- Department of Internal Medicine, American Hellenic Educational Progressive Association (AHEPA) University Hospital, Thessaloniki, GRC
| | - Anastasios Papadopoulos
- Department of Internal Medicine, American Hellenic Educational Progressive Association (AHEPA) University Hospital, Thessaloniki, GRC
| | - Antonios Kalis
- Department of Internal Medicine, Mpodosakeio General Prefecture Hospital, Ptolemaida, GRC
| | - Dimitrios Giagkoulis
- Department of Internal Medicine, Mpodosakeio General Prefecture Hospital, Ptolemaida, GRC
| | - Fotios Lezgidis
- Department of Internal Medicine, Mpodosakeio General Prefecture Hospital, Ptolemaida, GRC
| | - Christos Savopoulos
- Department of Internal Medicine, American Hellenic Educational Progressive Association (AHEPA) University Hospital, Thessaloniki, GRC
| |
Collapse
|
9
|
Clinkenbeard E. Fibroblast Growth Factor 23 Bone Regulation and Downstream Hormonal Activity. Calcif Tissue Int 2023; 113:4-20. [PMID: 37306735 DOI: 10.1007/s00223-023-01092-1] [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: 03/05/2023] [Accepted: 05/01/2023] [Indexed: 06/13/2023]
Abstract
Mineral homeostasis of calcium and phosphate levels is one critical component to the maintenance of bone mineral density (BMD) and strength. Diseases that disrupt calcium and phosphate balanced have highlighted not only the role these minerals play in overall bone homeostasis, but also the factors, hormones and downstream transporters, responsible for mineral metabolism. The key phosphaturic hormone elucidated from studying rare heritable disorders of hypophosphatemia is Fibroblast Growth Factor 23 (FGF23). FGF23 is predominantly secreted from bone cells in an effort to maintain phosphate balance by directly controlling renal reabsorption and indirectly affecting intestinal uptake of this mineral. Multiple factors have been shown to enhance bone mRNA expression; however, FGF23 can also undergo proteolytic cleavage to control secretion of the biologically active form of the hormone. The review focuses specifically on the regulation of FGF23 and its secretion from bone as well as its hormonal actions under physiological and disease conditions.
Collapse
Affiliation(s)
- Erica Clinkenbeard
- Department of Medical and Molecular Genetics, School of Medicine, Indiana University, 635 Barnhill Drive MS 5023, Indianapolis, IN, 46202, USA.
| |
Collapse
|
10
|
Pike JW, Lee SM, Meyer MB. Molecular insights into mineralotropic hormone inter-regulation. Front Endocrinol (Lausanne) 2023; 14:1213361. [PMID: 37441497 PMCID: PMC10334211 DOI: 10.3389/fendo.2023.1213361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 06/13/2023] [Indexed: 07/15/2023] Open
Abstract
The regulation of mineral homeostasis involves the three mineralotropic hormones PTH, FGF23 and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Early research efforts focused on PTH and 1,25(OH)2D3 and more recently on FGF23 have revealed that each of these hormones regulates the expression of the other two. Despite early suggestions of transcriptional processes, it has been only recently that research effort have begun to delineate the genomic mechanisms underpinning this regulation for 1,25(OH)2D3 and FGF23; the regulation of PTH by 1,25(OH)2D3, however, remains obscure. We review here our molecular understanding of how PTH induces Cyp27b1 expression, the gene encoding the enzyme responsible for the synthesis of 1,25(OH)2D3. FGF23 and 1,25(OH)2D3, on the other hand, function by suppressing production of 1,25(OH)2D3. PTH stimulates the PKA-induced recruitment of CREB and its coactivator CBP at CREB occupied sites within the kidney-specific regulatory regions of Cyp27b1. PKA activation also promotes the nuclear translocation of SIK bound coactivators such as CRTC2, where it similarly interacts with CREB occupied Cyp27b1 sites. The negative actions of both FGF23 and 1,25(OH)2D3 appear to suppress Cyp27b1 expression by opposing the recruitment of CREB coactivators at this gene. Reciprocal gene actions are seen at Cyp24a1, the gene encoding the enzyme that degrades 1,25(OH)2D3, thereby contributing to the overall regulation of blood levels of 1,25(OH)2D3. Relative to PTH regulation, we summarize what is known of how 1,25(OH)2D3 regulates PTH suppression. These studies suggest that it is not 1,25(OH)2D3 that controls PTH levels in healthy subjects, but rather calcium itself. Finally, we describe current progress using an in vivo approach that furthers our understanding of the regulation of Fgf23 expression by PTH and 1,25(OH)2D3 and provide the first evidence that P may act to induce Fgf23 expression via a complex transcriptional mechanism in bone. It is clear, however, that additional advances will need to be made to further our understanding of the inter-regulation of each of these hormonal genes.
Collapse
Affiliation(s)
- J. Wesley Pike
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, United States
| | - Seong Min Lee
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Mark B. Meyer
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, United States
| |
Collapse
|
11
|
Aobulikasimu A, Liu T, Piao J, Sato S, Ochi H, Okawa A, Tsuji K, Asou Y. SIRT6-PAI-1 axis is a promising therapeutic target in aging-related bone metabolic disruption. Sci Rep 2023; 13:7991. [PMID: 37198221 DOI: 10.1038/s41598-023-33297-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 04/11/2023] [Indexed: 05/19/2023] Open
Abstract
The mechanistic regulation of bone mass in aged animals is poorly understood. In this study, we examined the role of SIRT6, a longevity-associated factor, in osteocytes, using mice lacking Sirt6 in Dmp-1-expressing cells (cKO mice) and the MLO-Y4 osteocyte-like cell line. cKO mice exhibited increased osteocytic expression of Sost, Fgf23 and senescence inducing gene Pai-1 and the senescence markers p16 and Il-6, decreased serum phosphate levels, and low-turnover osteopenia. The cKO phenotype was reversed in mice that were a cross of PAI-1-null mice with cKO mice. Furthermore, senescence induction in MLO-Y4 cells increased the Fgf23 and Sost mRNA expression. Sirt6 knockout and senescence induction increased HIF-1α binding to the Fgf23 enhancer sequence. Bone mass and serum phosphate levels were higher in PAI-1-null aged mice than in wild-type mice. Therefore, SIRT6 agonists or PAI-1 inhibitors may be promising therapeutic options for aging-related bone metabolism disruptions.
Collapse
Affiliation(s)
- Alkebaier Aobulikasimu
- Department of Orthopedics Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo-Ku, Tokyo, 113-8519, Japan
| | - Tao Liu
- Department of Orthopedics Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo-Ku, Tokyo, 113-8519, Japan
| | - Jinying Piao
- Department of Orthopedics Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo-Ku, Tokyo, 113-8519, Japan
| | - Shingo Sato
- Department of Orthopedics Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo-Ku, Tokyo, 113-8519, Japan
| | - Hiroki Ochi
- Department of Rehabilitation for Movement Functions, Research Institute, National Rehabilitation Center for Persons With Disabilities, Tokorozawa-Shi, Saitama, Japan
| | - Atsushi Okawa
- Department of Orthopedics Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo-Ku, Tokyo, 113-8519, Japan
| | - Kunikazu Tsuji
- Department of Orthopedics Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo-Ku, Tokyo, 113-8519, Japan
| | - Yoshinori Asou
- Department of Orthopedics Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo-Ku, Tokyo, 113-8519, Japan.
| |
Collapse
|
12
|
Padhy B, Kapuganti RS, Hayat B, Mohanty PP, Alone DP. Wide-spread enhancer effect of SNP rs2279590 on regulating epoxide hydrolase-2 and protein tyrosine kinase 2-beta gene expression. Gene 2023; 854:147096. [PMID: 36470481 DOI: 10.1016/j.gene.2022.147096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 10/20/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022]
Abstract
Polymorphisms in the PTK2B-CLU locus have been associated with various neurodegenerative disorders including pseudoexfoliation glaucoma, Alzheimer's and Parkinson's. Many of these genomic variants are within enhancer elements and modulate genes associated with the disease pathogenesis. However, mechanisms by which they control the gene expression is unknown. Previously, we have shown that clusterin enhancer element surrounding rs2279590 intronic variant, a risk factor in the pathogenesis of pseudoexfoliation glaucoma modulates gene expression of clusterin (CLU), protein tyrosine kinase 2 beta (PTK2B) and epoxide hydrolase 2 (EPHX2). Here, we explored the mechanism by which rs2279590 enhancer regulates their gene expression through chromosome conformation capture assays. 3C assays revealed a strong enhancer-promoter chromatin interaction between rs2279590 enhancer and promoters of genes CLU, PTK2B and EPHX2 in the HEK293 wild type cells. Moreover, genomic knockout of rs2279590 element significantly decreases the chromatin-chromatin cross-linking frequency suggesting gene regulation at transcriptional level through formation of chromatin loop. In addition, molecular assays showed a significantly decreased expression of EPHX2 but not PTK2B at both mRNA and protein level in the lens capsule of pseudoexfoliation affected patients in comparison to control subjects implying a role of EPHX2 in the pathogenesis of pseudoexfoliation.
Collapse
Affiliation(s)
- Biswajit Padhy
- School of Biological Sciences, National Institute of Science Education and Research (NISER) Bhubaneswar, P.O. Bhimpur-Padanpur, Jatni, Khurda, Odisha 752050, India; Homi Bhabha National Institute (HBNI), Training School Complex, Anushaktinagar, Mumbai 400094, India
| | - Ramani Shyam Kapuganti
- School of Biological Sciences, National Institute of Science Education and Research (NISER) Bhubaneswar, P.O. Bhimpur-Padanpur, Jatni, Khurda, Odisha 752050, India; Homi Bhabha National Institute (HBNI), Training School Complex, Anushaktinagar, Mumbai 400094, India
| | - Bushra Hayat
- School of Biological Sciences, National Institute of Science Education and Research (NISER) Bhubaneswar, P.O. Bhimpur-Padanpur, Jatni, Khurda, Odisha 752050, India; Homi Bhabha National Institute (HBNI), Training School Complex, Anushaktinagar, Mumbai 400094, India
| | | | - Debasmita Pankaj Alone
- School of Biological Sciences, National Institute of Science Education and Research (NISER) Bhubaneswar, P.O. Bhimpur-Padanpur, Jatni, Khurda, Odisha 752050, India; Homi Bhabha National Institute (HBNI), Training School Complex, Anushaktinagar, Mumbai 400094, India.
| |
Collapse
|
13
|
Cassidy A, Onal M, Pelletier S. Novel methods for the generation of genetically engineered animal models. Bone 2023; 167:116612. [PMID: 36379415 PMCID: PMC9936561 DOI: 10.1016/j.bone.2022.116612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/08/2022] [Accepted: 11/09/2022] [Indexed: 11/15/2022]
Abstract
Genetically modified mouse models have shaped our understanding of biological systems in both physiological and pathological conditions. For decades, mouse genome engineering has relied on transgenesis and spontaneous gene replacement in embryonic stem (ES) cells. While these technologies provided a wealth of knowledge, they remain imprecise and expensive to use. Recent advances in genome editing technologies such as the development of targetable nucleases, the improvement of delivery systems, and the simplification of targeting strategies now allow for the rapid, precise manipulation of the mouse genome. In this review article, we discuss novel methods and targeting strategies for the generation of mouse models for the study of bone and skeletal muscle biology.
Collapse
Affiliation(s)
- Annelise Cassidy
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Melda Onal
- Department of Physiology and Cell Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Stephane Pelletier
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA.
| |
Collapse
|
14
|
Abstract
Hypophosphatemic rickets typically presents in infancy or early childhood with skeletal deformities and growth plate abnormalities. The most common causes are genetic (such as X-linked hypophosphatemia), and these typically will result in lifelong hypophosphatemia and osteomalacia. Knowledge of phosphate metabolism, including the effects of fibroblast growth factor 23 (FGF23) (an osteocyte produced hormone that downregulates renal phosphate reabsorption and 1,25-dihydroxyvitamin-D (1,25(OH)2D) production), is critical to determining the underlying genetic or acquired causes of hypophosphatemia and to facilitate appropriate treatment. Serum phosphorus should be measured in any child or adult with musculoskeletal complaints suggesting rickets or osteomalacia. Clinical evaluation incudes thorough history, physical examination, laboratory investigations, genetic analysis (especially in the absence of a guiding family history), and imaging to establish etiology and to monitor severity and treatment course. The treatment depends on the underlying cause, but often includes active forms of vitamin D combined with phosphate salts, or anti-FGF23 antibody treatment (burosumab) for X-linked hypophosphatemia. The purpose of this article is to explore the approach to evaluating hypophosphatemic rickets and its treatment options.
Collapse
Affiliation(s)
- Sarah A Ackah
- Department of Medicine, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Erik A Imel
- Department of Medicine, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| |
Collapse
|
15
|
Latic N, Erben RG. Interaction of Vitamin D with Peptide Hormones with Emphasis on Parathyroid Hormone, FGF23, and the Renin-Angiotensin-Aldosterone System. Nutrients 2022; 14:nu14235186. [PMID: 36501215 PMCID: PMC9736617 DOI: 10.3390/nu14235186] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/29/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022] Open
Abstract
The seminal discoveries that parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) are major endocrine regulators of vitamin D metabolism led to a significant improvement in our understanding of the pivotal roles of peptide hormones and small proteohormones in the crosstalk between different organs, regulating vitamin D metabolism. The interaction of vitamin D, FGF23 and PTH in the kidney is essential for maintaining mineral homeostasis. The proteohormone FGF23 is mainly secreted from osteoblasts and osteoclasts in the bone. FGF23 acts on proximal renal tubules to decrease production of the active form of vitamin D (1,25(OH)2D) by downregulating transcription of 1α-hydroxylase (CYP27B1), and by activating transcription of the key enzyme responsible for vitamin D degradation, 24-hydroxylase (CYP24A1). Conversely, the peptide hormone PTH stimulates 1,25(OH)2D renal production by upregulating the expression of 1α-hydroxylase and downregulating that of 24-hydroxylase. The circulating concentration of 1,25(OH)2D is a positive regulator of FGF23 secretion in the bone, and a negative regulator of PTH secretion from the parathyroid gland, forming feedback loops between kidney and bone, and between kidney and parathyroid gland, respectively. In recent years, it has become clear that vitamin D signaling has important functions beyond mineral metabolism. Observation of seasonal variations in blood pressure and the subsequent identification of vitamin D receptor (VDR) and 1α-hydroxylase in non-renal tissues such as cardiomyocytes, endothelial and smooth muscle cells, suggested that vitamin D may play a role in maintaining cardiovascular health. Indeed, observational studies in humans have found an association between vitamin D deficiency and hypertension, left ventricular hypertrophy and heart failure, and experimental studies provided strong evidence for a role of vitamin D signaling in the regulation of cardiovascular function. One of the proposed mechanisms of action of vitamin D is that it functions as a negative regulator of the renin-angiotensin-aldosterone system (RAAS). This finding established a novel link between vitamin D and RAAS that was unexplored until then. During recent years, major progress has been made towards a more complete understanding of the mechanisms by which FGF23, PTH, and RAAS regulate vitamin D metabolism, especially at the genomic level. However, there are still major gaps in our knowledge that need to be filled by future research. The purpose of this review is to highlight our current understanding of the molecular mechanisms underlying the interaction between vitamin D, FGF23, PTH, and RAAS, and to discuss the role of these mechanisms in physiology and pathophysiology.
Collapse
|
16
|
Portales-Castillo I, Simic P. PTH, FGF-23, Klotho and Vitamin D as regulators of calcium and phosphorus: Genetics, epigenetics and beyond. Front Endocrinol (Lausanne) 2022; 13:992666. [PMID: 36246903 PMCID: PMC9558279 DOI: 10.3389/fendo.2022.992666] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 09/12/2022] [Indexed: 11/30/2022] Open
Abstract
The actions of several bone-mineral ion regulators, namely PTH, FGF23, Klotho and 1,25(OH)2 vitamin D (1,25(OH)2D), control calcium and phosphate metabolism, and each of these molecules has additional biological effects related to cell signaling, metabolism and ultimately survival. Therefore, these factors are tightly regulated at various levels - genetic, epigenetic, protein secretion and cleavage. We review the main determinants of mineral homeostasis including well-established genetic and post-translational regulators and bring attention to the epigenetic mechanisms that affect the function of PTH, FGF23/Klotho and 1,25(OH)2D. Clinically relevant epigenetic mechanisms include methylation of cytosine at CpG-rich islands, histone deacetylation and micro-RNA interference. For example, sporadic pseudohypoparathyroidism type 1B (PHP1B), a disease characterized by resistance to PTH actions due to blunted intracellular cAMP signaling at the PTH/PTHrP receptor, is associated with abnormal methylation at the GNAS locus, thereby leading to reduced expression of the stimulatory G protein α-subunit (Gsα). Post-translational regulation is critical for the function of FGF-23 and such modifications include glycosylation and phosphorylation, which regulate the cleavage of FGF-23 and hence the proportion of available FGF-23 that is biologically active. While there is extensive data on how 1,25(OH)2D and the vitamin D receptor (VDR) regulate other genes, much more needs to be learned about their regulation. Reduced VDR expression or VDR mutations are the cause of rickets and are thought to contribute to different disorders. Epigenetic changes, such as increased methylation of the VDR resulting in decreased expression are associated with several cancers and infections. Genetic and epigenetic determinants play crucial roles in the function of mineral factors and their disorders lead to different diseases related to bone and beyond.
Collapse
Affiliation(s)
- Ignacio Portales-Castillo
- Department of Medicine, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Petra Simic
- Department of Medicine, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| |
Collapse
|
17
|
Abstract
Inorganic phosphate (Pi) in the mammalian body is balanced by its influx and efflux through the intestines, kidneys, bones, and soft tissues, at which several sodium/Pi co-transporters mediate its active transport. Pi homeostasis is achieved through the complex counter-regulatory feedback balance between fibroblast growth factor 23 (FGF23), 1,25-dihydroxyvitamin D (1,25(OH)2D), and parathyroid hormone. FGF23, which is mainly produced by osteocytes in bone, plays a central role in Pi homeostasis and exerts its effects by binding to the FGF receptor (FGFR) and αKlotho in distant target organs. In the kidneys, the main target, FGF23 promotes the excretion of Pi and suppresses the production of 1,25(OH)2D. Deficient and excess FGF23 result in hyperphosphatemia and hypophosphatemia, respectively. FGF23-related hypophosphatemic rickets/osteomalacia include tumor-induced osteomalacia and various genetic diseases, such as X-linked hypophosphatemic rickets. Coverage by the national health insurance system in Japan for the measurement of FGF23 and the approval of burosumab, an FGF23-neutralizing antibody, have had a significant impact on the diagnosis and treatment of FGF23-related hypophosphatemic rickets/osteomalacia. Some of the molecules responsible for genetic hypophosphatemic rickets/osteomalacia are highly expressed in osteocytes and function as local regulators of FGF23 production. A number of systemic factors also regulate FGF23 levels. Although the mechanisms responsible for Pi sensing in mammals have not yet been elucidated in detail, recent studies have suggested the involvement of FGFR1. The further clarification of the mechanisms by which osteocytes detect Pi levels and regulate FGF23 production will lead to the development of better strategies to treat hyperphosphatemic and hypophosphatemic conditions.
Collapse
Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka 594-1101, Japan
| |
Collapse
|
18
|
Hasan M, Oster M, Reyer H, Ponsuksili S, Murani E, Wolf P, Fischer DC, Wimmers K. Tissue-Wide Expression of Genes Related to Vitamin D Metabolism and FGF23 Signaling following Variable Phosphorus Intake in Pigs. Metabolites 2022; 12:metabo12080729. [PMID: 36005601 PMCID: PMC9413461 DOI: 10.3390/metabo12080729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/01/2022] [Accepted: 08/02/2022] [Indexed: 11/16/2022] Open
Abstract
Calcium (Ca) and phosphorus (P) homeostasis is maintained by several regulators, including vitamin D and fibroblast growth factor 23 (FGF23), and their tissue-specific activation and signaling cascades. In this study, the tissue-wide expression of key genes linked to vitamin D metabolism (CYP2R1, CYP27A1, CYP27B1, CYP24A1, GC, VDR) and FGF23 signaling (FGF23, FGFR1-4, KL) were investigated in pigs fed conventional (trial 1) and divergent P diets (trial 2). The tissue set comprised kidney, liver, bone, lung, aorta, and gastrointestinal tract sections. Expression patterns revealed that non-renal tissues and cells (NRTC) express genes to form active vitamin D [1,25(OH)2D3] according to site-specific requirements. A low P diet resulted in higher serum calcitriol and increased CYP24A1 expression in the small intestine, indicating local suppression of vitamin D signaling. A high P diet prompted increased mRNA abundances of CYP27B1 for local vitamin D synthesis, specifically in bone. For FGF23 signaling, analyses revealed ubiquitous expression of FGFR1-4, whereas KL was expressed in a tissue-specific manner. Dietary P supply did not affect skeletal FGF23; however, FGFR4 and KL showed increased expression in bone at high P supply, suggesting regulation to balance mineralization. Specific NRTC responses influence vitamin D metabolism and P homeostasis, which should be considered for a thrifty but healthy P supply.
Collapse
Affiliation(s)
- Maruf Hasan
- Research Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
| | - Michael Oster
- Research Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
| | - Henry Reyer
- Research Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
| | - Siriluck Ponsuksili
- Research Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
| | - Eduard Murani
- Research Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
| | - Petra Wolf
- Faculty of Agricultural and Environmental Sciences, University of Rostock, Justus-von-Liebig-Weg 6b, 18059 Rostock, Germany
| | - Dagmar-Christiane Fischer
- Department of Pediatrics, Rostock University Hospital, Ernst-Heydemann-Str. 8, 18057 Rostock, Germany
| | - Klaus Wimmers
- Research Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
- Faculty of Agricultural and Environmental Sciences, University of Rostock, Justus-von-Liebig-Weg 6b, 18059 Rostock, Germany
- Correspondence: ; Tel.: +49-38208-68600
| |
Collapse
|
19
|
Vervloet MG. Shedding Light on the Complex Regulation of FGF23. Metabolites 2022; 12:metabo12050401. [PMID: 35629904 PMCID: PMC9147863 DOI: 10.3390/metabo12050401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/23/2022] [Accepted: 04/26/2022] [Indexed: 12/10/2022] Open
Abstract
Early research has suggested a rather straightforward relation between phosphate exposure, increased serum FGF23 (Fibroblast Growth Factor 23) concentrations and clinical endpoints. Unsurprisingly, however, subsequent studies have revealed a much more complex interplay between autocrine and paracrine factors locally in bone like PHEX and DMP1, concentrations of minerals in particular calcium and phosphate, calciprotein particles, and endocrine systems like parathyroid hormone PTH and the vitamin D system. In addition to these physiological regulators, an expanding list of disease states are shown to influence FGF23 levels, usually increasing it, and as such increase the burden of disease. While some of these physiological or pathological factors, like inflammatory cytokines, may partially confound the association of FGF23 and clinical endpoints, others are in the same causal path, are targetable and hence hold the promise of future treatment options to alleviate FGF23-driven toxicity, for instance in chronic kidney disease, the FGF23-associated disease with the highest prevalence by far. These factors will be reviewed here and their relative importance described, thereby possibly opening potential means for future therapeutic strategies.
Collapse
Affiliation(s)
- Marc G. Vervloet
- Amsterdam UMC, Location Vrije Universiteit Amsterdam, Nephrology, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands; ; Tel.: +31-20-4442671
- Amsterdam Cardiovascular Sciences, Diabetes and Metabolism, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
| |
Collapse
|
20
|
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: 15] [Impact Index Per Article: 7.5] [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.
Collapse
|
21
|
Abstract
Apart from its phosphaturic action, the bone-derived hormone fibroblast growth factor-23 (FGF23) is also an essential regulator of vitamin D metabolism. The main target organ of FGF23 is the kidney, where FGF23 suppresses transcription of the key enzyme in vitamin D hormone (1,25(OH)2D) activation, 1α-hydroxylase, and activates transcription of the key enzyme responsible for vitamin D degradation, 24-hydroxylase, in proximal renal tubules. The circulating concentration of 1,25(OH)2D is a positive regulator of FGF23 secretion in bone, forming a feedback loop between kidney and bone. The importance of FGF23 as regulator of vitamin D metabolism is underscored by the fact that in the absence of FGF23 signaling, the tight control of renal 1α-hydroxylase fails, resulting in overproduction of 1,25(OH)2D in mice and men. During recent years, big strides have been made toward a more complete understanding of the mechanisms underlying the FGF23-mediated regulation of vitamin D metabolism, especially at the genomic level. However, there are still major gaps in our knowledge that need to be filled by future research. Importantly, the intracellular signaling cascades downstream of FGF receptors regulating transcription of 1α-hydroxylase and 24-hydroxylase in proximal renal tubules still remain unresolved. The purpose of this review is to highlight our current understanding of the molecular mechanisms underlying the regulation of vitamin D metabolism by FGF23, and to discuss the role of these mechanisms in physiology and pathophysiology. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Nejla Latic
- Department of Biomedical Sciences University of Veterinary Medicine Vienna Austria
| | - Reinhold G Erben
- Department of Biomedical Sciences University of Veterinary Medicine Vienna Austria
| |
Collapse
|
22
|
Inflammation: a putative link between phosphate metabolism and cardiovascular disease. Clin Sci (Lond) 2021; 135:201-227. [PMID: 33416083 PMCID: PMC7796315 DOI: 10.1042/cs20190895] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 12/11/2020] [Accepted: 12/15/2020] [Indexed: 02/06/2023]
Abstract
Dietary habits in the western world lead to increasing phosphate intake. Under physiological conditions, extraosseous precipitation of phosphate with calcium is prevented by a mineral buffering system composed of calcification inhibitors and tight control of serum phosphate levels. The coordinated hormonal regulation of serum phosphate involves fibroblast growth factor 23 (FGF23), αKlotho, parathyroid hormone (PTH) and calcitriol. A severe derangement of phosphate homeostasis is observed in patients with chronic kidney disease (CKD), a patient collective with extremely high risk of cardiovascular morbidity and mortality. Higher phosphate levels in serum have been associated with increased risk for cardiovascular disease (CVD) in CKD patients, but also in the general population. The causal connections between phosphate and CVD are currently incompletely understood. An assumed link between phosphate and cardiovascular risk is the development of medial vascular calcification, a process actively promoted and regulated by a complex mechanistic interplay involving activation of pro-inflammatory signalling. Emerging evidence indicates a link between disturbances in phosphate homeostasis and inflammation. The present review focuses on critical interactions of phosphate homeostasis, inflammation, vascular calcification and CVD. Especially, pro-inflammatory responses mediating hyperphosphatemia-related development of vascular calcification as well as FGF23 as a critical factor in the interplay between inflammation and cardiovascular alterations, beyond its phosphaturic effects, are addressed.
Collapse
|
23
|
Bayer J, Vaghela R, Drechsler S, Osuchowski MF, Erben RG, Andrukhova O. The bone is the major source of high circulating intact fibroblast growth factor-23 in acute murine polymicrobial sepsis induced by cecum ligation puncture. PLoS One 2021; 16:e0251317. [PMID: 33989306 PMCID: PMC8121358 DOI: 10.1371/journal.pone.0251317] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 04/23/2021] [Indexed: 12/20/2022] Open
Abstract
Fibroblast growth factor-23 (FGF23), a bone-produced hormone, plays a critical role in mineral homeostasis. Human diseases associated with excessive intact circulating FGF23 (iFGF23) result in hypophosphatemia and low vitamin D hormone in patients with normal kidney function. In addition, there is accumulating evidence linking FGF23 with inflammation. Based on these studies and the frequent observation of hypophosphatemia among septic patients, we sought to elucidate further the relationship between FGF23 and mineral homeostasis in a clinically relevant murine polymicrobial sepsis model. Medium-severity sepsis was induced by cecum ligation puncture (CLP) in adult CD-1 mice of both sexes. Healthy CD-1 mice (without CLP) were used as controls. Forty-eight hours post-CLP, spontaneous urine was collected, and serum, organs and bones were sampled at necropsy. Serum iFGF23 increased ~20-fold in CLP compared to control mice. FGF23 protein concentration was increased in the bones, but not in spleen or liver of CLP mice. Despite the ~20-fold iFGF23 increase, we did not observe any significant changes in mineral homeostasis or parathyroid hormone levels in the blood of CLP animals. Urinary excretion of phosphate, calcium, and sodium remained unchanged in male CLP mice, whereas female CLP mice exhibited lower urinary calcium excretion, relative to healthy controls. In line with renal FGF23 resistance, expression of phosphate-, calcium- and sodium-transporting proteins did not show consistent changes in the kidneys of male and female CLP mice. Renal expression of the co-receptor αKlotho was downregulated in female, but not in male CLP mice. In conclusion, our data demonstrate that the dramatic, sex-independent rise in serum iFGF23 post-CLP was mainly caused by an upregulation of FGF23 secretion in the bone. Surprisingly, the upsurge in circulating iFGF23 did not alter humoral mineral homeostasis in the acutely septic mice. Hence, the biological function of elevated FGF23 in sepsis remains unclear and warrants further studies.
Collapse
Affiliation(s)
- Jessica Bayer
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Ravikumar Vaghela
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Susanne Drechsler
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology in the AUVA Research Center, Vienna, Austria
| | - Marcin F. Osuchowski
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology in the AUVA Research Center, Vienna, Austria
| | - Reinhold G. Erben
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
- * E-mail:
| | - Olena Andrukhova
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna, Austria
| |
Collapse
|
24
|
Radhakrishnan K, Kim YH, Jung YS, Kim DK, Na SY, Lim D, Kim DH, Kim J, Kim HS, Choy HE, Cho SJ, Lee IK, Ayvaz Ş, Nittka S, Fliser D, Schunk SJ, Speer T, Dooley S, Lee CH, Choi HS. Orphan nuclear receptor ERR-γ regulates hepatic FGF23 production in acute kidney injury. Proc Natl Acad Sci U S A 2021; 118. [DOI: https:/doi.org/10.1073/pnas.2022841118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/18/2023] Open
Abstract
Significance
Bone is the main source of fibroblast growth factor 23 (FGF23), which is important for phosphate and vitamin D homeostasis. In acute kidney injury (AKI), high blood levels of FGF23 are positively correlated with disease progression and increased risk of mortality. Reducing adverse plasma FGF23 levels in AKI patients is favorable. We showed here that hepatocytes are the major source of circulating FGF23, and orphan nuclear receptor ERR-γ is a novel transcriptional regulator of hepatic FGF23 production in AKI. Liver-specific depletion of ERR-γ or ERR-γ inverse agonist, GSK5182, significantly reduced plasma levels of FGF23 in AKI. This study reveals liver is the source of FGF23 and a therapeutic strategy to control pathologically adverse plasma FGF23 levels in AKI.
Collapse
Affiliation(s)
- Kamalakannan Radhakrishnan
- School of Biological Sciences and Technology, Chonnam National University, 61186 Gwangju, Republic of Korea
| | - Yong-Hoon Kim
- Laboratory Animal Resource Center, Korea Research Institute of Bioscience and Biotechnology, 34141 Daejeon, Republic of Korea
- Department of Functional Genomics, Korea Research Institute of Biosciences and Biotechnology School of Bioscience, University of Science and Technology, 34141 Daejeon, Republic of Korea
| | - Yoon Seok Jung
- School of Biological Sciences and Technology, Chonnam National University, 61186 Gwangju, Republic of Korea
| | - Don-Kyu Kim
- Department of Molecular Biotechnology, Chonnam National University, 61186 Gwangju, Republic of Korea
| | - Soon-Young Na
- School of Biological Sciences and Technology, Chonnam National University, 61186 Gwangju, Republic of Korea
| | - Daejin Lim
- Department of Microbiology, Chonnam National University Medical School, 61468 Gwangju, Republic of Korea
| | - Dong Hun Kim
- Department of Biomedical Science, Graduate School, Kyungpook National University, 41404 Daegu, Republic of Korea
| | - Jina Kim
- New Drug Development Center, Daegu Gyeongbuk Medical Innovation Foundation, 41061 Daegu, Republic of Korea
| | - Hyung-Seok Kim
- Department of Forensic Medicine, Chonnam National University Medical School, 61468 Gwangju, Republic of Korea
| | - Hyon E. Choy
- Department of Microbiology, Chonnam National University Medical School, 61468 Gwangju, Republic of Korea
| | - Sung Jin Cho
- New Drug Development Center, Daegu Gyeongbuk Medical Innovation Foundation, 41061 Daegu, Republic of Korea
- Leading-edge Research Center for Drug Discovery and Development for Diabetes and Metabolic Disease, Kyungpook National University Hospital, 41404 Daegu, Republic of Korea
| | - In-Kyu Lee
- Leading-edge Research Center for Drug Discovery and Development for Diabetes and Metabolic Disease, Kyungpook National University Hospital, 41404 Daegu, Republic of Korea
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Kyungpook National University Hospital, 41944 Daegu, Republic of Korea
| | - Şamil Ayvaz
- Department of Medicine II, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Stefanie Nittka
- Institute for Clinical Chemistry, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Danilo Fliser
- Department of Internal Medicine IV, Nephrology and Hypertension, Saarland University, D-66421 Homburg/Saar, Germany
| | - Stefan J. Schunk
- Department of Internal Medicine IV, Nephrology and Hypertension, Saarland University, D-66421 Homburg/Saar, Germany
| | - Thimoteus Speer
- Department of Internal Medicine IV, Nephrology and Hypertension, Saarland University, D-66421 Homburg/Saar, Germany
| | - Steven Dooley
- Department of Medicine II, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Chul-Ho Lee
- Laboratory Animal Resource Center, Korea Research Institute of Bioscience and Biotechnology, 34141 Daejeon, Republic of Korea
- Department of Functional Genomics, Korea Research Institute of Biosciences and Biotechnology School of Bioscience, University of Science and Technology, 34141 Daejeon, Republic of Korea
| | - Hueng-Sik Choi
- School of Biological Sciences and Technology, Chonnam National University, 61186 Gwangju, Republic of Korea
| |
Collapse
|
25
|
Orphan nuclear receptor ERR-γ regulates hepatic FGF23 production in acute kidney injury. Proc Natl Acad Sci U S A 2021; 118:2022841118. [PMID: 33853949 DOI: 10.1073/pnas.2022841118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Fibroblast growth factor 23 (FGF23), a hormone generally derived from bone, is important in phosphate and vitamin D homeostasis. In acute kidney injury (AKI) patients, high-circulating FGF23 levels are associated with disease progression and mortality. However, the organ and cell type of FGF23 production in AKI and the molecular mechanism of its excessive production are still unidentified. For insight, we investigated folic acid (FA)-induced AKI in mice. Interestingly, simultaneous with FGF23, orphan nuclear receptor ERR-γ expression is increased in the liver of FA-treated mice, and ectopic overexpression of ERR-γ was sufficient to induce hepatic FGF23 production. In patients and in mice, AKI is accompanied by up-regulated systemic IL-6, which was previously identified as an upstream regulator of ERR-γ expression in the liver. Administration of IL-6 neutralizing antibody to FA-treated mice or of recombinant IL-6 to healthy mice confirms IL-6 as an upstream regulator of hepatic ERR-γ-mediated FGF23 production. A significant (P < 0.001) interconnection between high IL-6 and FGF23 levels as a predictor of AKI in patients that underwent cardiac surgery was also found, suggesting the clinical relevance of the finding. Finally, liver-specific depletion of ERR-γ or treatment with an inverse ERR-γ agonist decreased hepatic FGF23 expression and plasma FGF23 levels in mice with FA-induced AKI. Thus, inverse agonist of ERR-γ may represent a therapeutic strategy to reduce adverse plasma FGF23 levels in AKI.
Collapse
|
26
|
Haussler MR, Livingston S, Sabir ZL, Haussler CA, Jurutka PW. Vitamin D Receptor Mediates a Myriad of Biological Actions Dependent on Its 1,25-Dihydroxyvitamin D Ligand: Distinct Regulatory Themes Revealed by Induction of Klotho and Fibroblast Growth Factor-23. JBMR Plus 2021; 5:e10432. [PMID: 33553988 PMCID: PMC7839824 DOI: 10.1002/jbm4.10432] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 11/01/2020] [Indexed: 11/21/2022] Open
Abstract
The hormonal vitamin D metabolite, 1,25‐dihydroxyvitamin D [1,25(OH)2D], produced in kidney, acts in numerous end organs via the nuclear vitamin D receptor (VDR) to trigger molecular events that orchestrate bone mineral homeostasis. VDR is a ligand‐controlled transcription factor that obligatorily heterodimerizes with retinoid X receptor (RXR) to target vitamin D responsive elements (VDREs) in the vicinity of vitamin D‐regulated genes. Circulating 1,25(OH)2D concentrations are governed by PTH, an inducer of renal D‐hormone biosynthesis catalyzed by CYP27B1 that functions as the key player in a calcemic endocrine circuit, and by fibroblast growth factor‐23 (FGF23), a repressor of the CYP27B1 renal enzyme, creating a hypophosphatemic endocrine loop. 1,25(OH)2D/VDR–RXR acts in kidney to induce Klotho (a phosphaturic coreceptor for FGF23) to correct hyperphosphatemia, NPT2a/c to correct hypophosphatemia, and TRPV5 and CaBP28k to enhance calcium reabsorption. 1,25(OH)2D‐liganded VDR–RXR functions in osteoblasts/osteocytes by augmenting RANK‐ligand expression to paracrine signal osteoclastic bone resorption, while simultaneously inducing FGF23, SPP1, BGLP, LRP5, ANK1, ENPP1, and TNAP, and conversely repressing RUNX2 and PHEX expression, effecting localized control of mineralization to sculpt the skeleton. Herein, we document the history of 1,25(OH)2D/VDR and summarize recent advances in characterizing their physiology, biochemistry, and mechanism of action by highlighting two examples of 1,25(OH)2D/VDR molecular function. The first is VDR‐mediated primary induction of Klotho mRNA by 1,25(OH)2D in kidney via a mechanism initiated by the docking of liganded VDR–RXR on a VDRE at −35 kb in the mouse Klotho gene. In contrast, the secondary induction of FGF23 by 1,25(OH)2D in bone is proposed to involve rapid nongenomic action of 1,25(OH)2D/VDR to acutely activate PI3K, in turn signaling the induction of MZF1, a transcription factor that, in cooperation with c‐ets1‐P, binds to an enhancer element centered at −263 bp in the promoter‐proximal region of the mouse fgf23 gene. Chronically, 1,25(OH)2D‐induced osteopontin apparently potentiates MZF1. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Mark R Haussler
- Department of Basic Medical Sciences University of Arizona College of Medicine-Phoenix Phoenix AZ
| | - Sarah Livingston
- School of Mathematical and Natural Sciences Arizona State University Glendale AZ
| | - Zhela L Sabir
- School of Mathematical and Natural Sciences Arizona State University Glendale AZ
| | - Carol A Haussler
- Department of Basic Medical Sciences University of Arizona College of Medicine-Phoenix Phoenix AZ
| | - Peter W Jurutka
- Department of Basic Medical Sciences University of Arizona College of Medicine-Phoenix Phoenix AZ.,School of Mathematical and Natural Sciences Arizona State University Glendale AZ
| |
Collapse
|
27
|
Agoro R, Park MY, Le Henaff C, Jankauskas S, Gaias A, Chen G, Mohammadi M, Sitara D. C-FGF23 peptide alleviates hypoferremia during acute inflammation. Haematologica 2021; 106:391-403. [PMID: 32193252 PMCID: PMC7849576 DOI: 10.3324/haematol.2019.237040] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 03/13/2020] [Indexed: 12/22/2022] Open
Abstract
Hypoferremia results as an acute phase response to infection and inflammation aiming to reduce iron availability to pathogens. Activation of toll-like receptors (TLR), the key sensors of the innate immune system, induces hypoferremia mainly through the rise of the iron hormone hepcidin. Conversely, stimulation of erythropoiesis suppresses hepcidin expression via induction of the erythropoietin-responsive hormone erythroferrone. Iron deficiency stimulates transcription of the osteocyte- secreted protein FGF23. Here we hypothesized that induction of FGF23 in response to TLR4 activation is a potent contributor to hypoferremia and, thus, impairment of its activity may alleviate hypoferremia induced by lipopolysaccharide (LPS), a TLR 4 agonist. We used the C-terminal tail of FGF23 to impair endogenous full-length FGF23 signaling in wildtype mice, and investigated its impact on hypoferremia. Our data show that FGF23 is induced as early as pro-inflammatory cytokines in response to LPS, followed by upregulation of hepcidin and downregulation of erythropoietin (Epo) expression in addition to decreased serum iron and transferrin saturation. Further, LPS-induced hepatic and circulating hepcidin were significantly reduced by FGF23 signaling disruption. Accordingly, iron sequestration in liver and spleen caused by TLR4 activation was completely abrogated by FGF23 signaling inhibition, resulting in alleviation of serum iron and transferrin saturation deficit. Taken together, our studies highlight for the first time that inhibition of FGF23 signaling alleviates LPS-induced acute hypoferremia.
Collapse
Affiliation(s)
- Rafiou Agoro
- Basic Science and Craniofacial Biology, NYU College of Dentistry, New York, USA
| | - Min Young Park
- Basic Science and Craniofacial Biology, NYU College of Dentistry, New York, USA
| | - Carole Le Henaff
- Basic Science and Craniofacial Biology, NYU College of Dentistry, New York, USA
| | | | - Alina Gaias
- Basic Science and Craniofacial Biology, NYU College of Dentistry, New York, USA
| | - Gaozhi Chen
- Chemical Biology Research Center, Wenzhou Medical University, Wenzhou, China
| | - Moosa Mohammadi
- Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, USA
| | - Despina Sitara
- NYU College of Dentistry and NYU School of Medicine, New York, USA
| |
Collapse
|
28
|
Ratsma DMA, Zillikens MC, van der Eerden BCJ. Upstream Regulators of Fibroblast Growth Factor 23. Front Endocrinol (Lausanne) 2021; 12:588096. [PMID: 33716961 PMCID: PMC7952762 DOI: 10.3389/fendo.2021.588096] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 01/11/2021] [Indexed: 12/11/2022] Open
Abstract
Fibroblast growth factor 23 (FGF23) has been described as an important regulator of mineral homeostasis, but has lately also been linked to iron deficiency, inflammation, and erythropoiesis. FGF23 is essential for the maintenance of phosphate homeostasis in the body and activating mutations in the gene itself or inactivating mutations in its upstream regulators can result in severe chronic hypophosphatemia, where an unbalanced mineral homeostasis often leads to rickets in children and osteomalacia in adults. FGF23 can be regulated by changes in transcriptional activity or by changes at the post-translational level. The balance between O-glycosylation and phosphorylation is an important determinant of how much active intact or inactive cleaved FGF23 will be released in the circulation. In the past years, it has become evident that iron deficiency and inflammation regulate FGF23 in a way that is not associated with its classical role in mineral metabolism. These conditions will not only result in an upregulation of FGF23 transcription, but also in increased cleavage, leaving the levels of active intact FGF23 unchanged. The exact mechanisms behind and function of this process are still unclear. However, a deeper understanding of FGF23 regulation in both the classical and non-classical way is important to develop better treatment options for diseases associated with disturbed FGF23 biology. In this review, we describe how the currently known upstream regulators of FGF23 change FGF23 transcription and affect its post-translational modifications at the molecular level.
Collapse
|
29
|
McKnight Q, Jenkins S, Li X, Nelson T, Marlier A, Cantley LG, Finberg KE, Fretz JA. IL-1β Drives Production of FGF-23 at the Onset of Chronic Kidney Disease in Mice. J Bone Miner Res 2020; 35:1352-1362. [PMID: 32154933 PMCID: PMC7363582 DOI: 10.1002/jbmr.4003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 02/14/2020] [Accepted: 03/04/2020] [Indexed: 12/27/2022]
Abstract
FGF-23 has arisen as an early biomarker of renal dysfunction, but at the onset of chronic kidney disease (CKD), data suggest that FGF-23 may be produced independently of the parathyroid hormone (PTH), 1,25(OH)2 -vitamin D3 signaling axis. Iron status is inversely correlated to the level of circulating FGF-23, and improvement in iron bioavailability within patients correlates with a decrease in FGF-23. Alternately, recent evidence also supports a regulatory role of inflammatory cytokines in the modulation of FGF-23 expression. To determine the identity of the signal from the kidney-inducing upregulation of osteocytic FGF-23 at the onset of CKD, we utilized a mouse model of congenital CKD that fails to properly mature the glomerular capillary tuft. We profiled the sequential presentation of indicators of renal dysfunction, phosphate imbalance, and iron bioavailability and transport to identify the events that initiate osteocytic production of FGF-23 during the onset of CKD. We report here that elevations in circulating intact-FGF-23 coincide with the earliest indicators of renal dysfunction (P14), and precede changes in serum phosphate or iron homeostasis. Serum PTH was also not changed within the first month. Instead, production of the inflammatory protein IL-1β from the kidney and systemic elevation of it in the circulation matched the induction of FGF-23. IL-1β's ability to induce FGF-23 was confirmed on bone chips in culture and within mice in vivo. Furthermore, neutralizing antibody to IL-1β blocked FGF-23 expression in both our congenital model of CKD and a second nephrotoxic serum-mediated model. We conclude that early CKD resembles a situation of primary FGF-23 excess mediated by inflammation. These findings do not preclude that altered mineral availability or anemia can later modulate FGF-23 levels but find that in early CKD they are not the driving stimulus for the initial upregulation of FGF-23. © 2020 American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Quiana McKnight
- Department of Internal Medicine (Nephrology), Yale University School of Medicine, New Haven, CT, USA
| | - Sarah Jenkins
- Department of Internal Medicine (Nephrology), Yale University School of Medicine, New Haven, CT, USA
| | - Xiuqi Li
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Tracy Nelson
- Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT, USA
| | - Arnaud Marlier
- Department of Internal Medicine (Nephrology), Yale University School of Medicine, New Haven, CT, USA
| | - Lloyd G Cantley
- Department of Internal Medicine (Nephrology), Yale University School of Medicine, New Haven, CT, USA
| | - Karin E Finberg
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Jackie A Fretz
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA.,Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT, USA
| |
Collapse
|
30
|
Czaya B, Faul C. FGF23 and inflammation-a vicious coalition in CKD. Kidney Int 2020; 96:813-815. [PMID: 31543148 DOI: 10.1016/j.kint.2019.05.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 05/09/2019] [Accepted: 05/13/2019] [Indexed: 11/26/2022]
Abstract
High serum concentrations of the phosphaturic hormone, fibroblast growth factor 23 (FGF23), contribute to various tissue injuries. In chronic kidney disease, the sources of FGF23 and the stimuli that control FGF23 production differ from those in the physiologic scenario. Mediators of inflammation are intensively studied as potential factors that contribute to FGF23 elevations and thereby might function as drug targets to lower FGF23 levels. The present study focuses on tumor necrosis factor.
Collapse
Affiliation(s)
- Brian Czaya
- Division of Nephrology, Department of Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Christian Faul
- Division of Nephrology, Department of Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA.
| |
Collapse
|
31
|
Babitt JL, Sitara D. Crosstalk between fibroblast growth factor 23, iron, erythropoietin, and inflammation in kidney disease. Curr Opin Nephrol Hypertens 2020; 28:304-310. [PMID: 31145704 PMCID: PMC6693648 DOI: 10.1097/mnh.0000000000000514] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW Recent research has revealed that regulation of the bone-secreted hormone fibroblast growth factor 23 (FGF23) is not limited to classical mineral factors. Specifically, bidirectional relationships have been described between FGF23 production and anemia, iron status, and inflammation. Here, we will review the latest published articles on the crosstalk between FGF23 and the aforementioned nonclassical factors. RECENT FINDINGS It has been recently reported that erythropoietin, iron deficiency, and inflammation increase FGF23 production and metabolism. Moreover, FGF23 promotes anemia and regulates inflammatory responses. These findings are particularly important in the setting of chronic kidney disease which is characterized by elevated FGF23 levels and several associated comorbidities. SUMMARY Regulation of FGF23 is complex and involves many bone and renal factors. More recently, erythropoietin, iron deficiency, and inflammation have been also shown to affect FGF23 transcription and cleavage. Importantly, FGF23 has emerged as a regulator of erythropoiesis, iron metabolism, and inflammation. These findings provide novel and important insights into the pathophysiologic mechanisms of chronic kidney disease and may present new opportunities for therapeutic clinical interventions.
Collapse
Affiliation(s)
- Jodie L Babitt
- Department of Medicine, Division of Nephrology, Program in Membrane Biology, Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Despina Sitara
- Department of Basic Science and Craniofacial Biology, New York University College of Dentistry.,Department of Medicine, New York University School of Medicine, New York, New York, USA
| |
Collapse
|
32
|
Simic P, Kim W, Zhou W, Pierce KA, Chang W, Sykes DB, Aziz NB, Elmariah S, Ngo D, Pajevic PD, Govea N, Kestenbaum BR, de Boer IH, Cheng Z, Christov M, Chun J, Leaf DE, Waikar SS, Tager AM, Gerszten RE, Thadhani RI, Clish CB, Jüppner H, Wein MN, Rhee EP. Glycerol-3-phosphate is an FGF23 regulator derived from the injured kidney. J Clin Invest 2020; 130:1513-1526. [PMID: 32065590 PMCID: PMC7269595 DOI: 10.1172/jci131190] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 12/11/2019] [Indexed: 12/24/2022] Open
Abstract
Fibroblast growth factor 23 (FGF23) is a bone-derived hormone that controls blood phosphate levels by increasing renal phosphate excretion and reducing 1,25-dihydroxyvitamin D3 [1,25(OH)2D] production. Disorders of FGF23 homeostasis are associated with significant morbidity and mortality, but a fundamental understanding of what regulates FGF23 production is lacking. Because the kidney is the major end organ of FGF23 action, we hypothesized that it releases a factor that regulates FGF23 synthesis. Using aptamer-based proteomics and liquid chromatography-mass spectrometry-based (LC-MS-based) metabolomics, we profiled more than 1600 molecules in renal venous plasma obtained from human subjects. Renal vein glycerol-3-phosphate (G-3-P) had the strongest correlation with circulating FGF23. In mice, exogenous G-3-P stimulated bone and bone marrow FGF23 production through local G-3-P acyltransferase-mediated (GPAT-mediated) lysophosphatidic acid (LPA) synthesis. Further, the stimulatory effect of G-3-P and LPA on FGF23 required LPA receptor 1 (LPAR1). Acute kidney injury (AKI), which increases FGF23 levels, rapidly increased circulating G-3-P in humans and mice, and the effect of AKI on FGF23 was abrogated by GPAT inhibition or Lpar1 deletion. Together, our findings establish a role for kidney-derived G-3-P in mineral metabolism and outline potential targets to modulate FGF23 production during kidney injury.
Collapse
Affiliation(s)
- Petra Simic
- Nephrology Division and.,Endocrine Unit, Endocrinology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Wondong Kim
- Nephrology Division and.,Endocrine Unit, Endocrinology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Wen Zhou
- Nephrology Division and.,Endocrine Unit, Endocrinology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Kerry A Pierce
- Broad Institute, Massachusetts Institute of Technology and Harvard University, Cambridge, Massachusetts, USA
| | - Wenhan Chang
- Endocrine Research Unit, San Francisco Veterans Affairs Medical Center, UCSF, San Francisco, California, USA
| | | | | | - Sammy Elmariah
- Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Debby Ngo
- Cardiovascular Research Center, Division of Cardiovascular Medicine, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Paola Divieti Pajevic
- Department of Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Nicolas Govea
- Endocrine Unit, Endocrinology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Bryan R Kestenbaum
- Kidney Research Institute, University of Washington Medicine and Northwest Kidney Centers, Seattle, Washington, USA
| | - Ian H de Boer
- Kidney Research Institute, University of Washington Medicine and Northwest Kidney Centers, Seattle, Washington, USA
| | - Zhiqiang Cheng
- Endocrine Research Unit, San Francisco Veterans Affairs Medical Center, UCSF, San Francisco, California, USA
| | - Marta Christov
- Department of Medicine, New York Medical College, Touro College, Valhalla, New York, USA
| | - Jerold Chun
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - David E Leaf
- Division of Renal (Kidney) Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Sushrut S Waikar
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Andrew M Tager
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
| | - Robert E Gerszten
- Broad Institute, Massachusetts Institute of Technology and Harvard University, Cambridge, Massachusetts, USA.,Cardiovascular Research Center, Division of Cardiovascular Medicine, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | | | - Clary B Clish
- Broad Institute, Massachusetts Institute of Technology and Harvard University, Cambridge, Massachusetts, USA
| | - Harald Jüppner
- Endocrine Unit, Endocrinology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA.,Pediatric Nephrology and Hypertension Program, Mass General for Children, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Marc N Wein
- Endocrine Unit, Endocrinology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Eugene P Rhee
- Nephrology Division and.,Endocrine Unit, Endocrinology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA.,Broad Institute, Massachusetts Institute of Technology and Harvard University, Cambridge, Massachusetts, USA
| |
Collapse
|
33
|
Kristjansdottir HL, Lewerin C, Lerner UH, Herlitz H, Johansson P, Johansson H, Karlsson M, Lorentzon M, Ohlsson C, Ljunggren Ö, Mellström D. High Plasma Erythropoietin Predicts Incident Fractures in Elderly Men with Normal Renal Function: The MrOS Sweden Cohort. J Bone Miner Res 2020; 35:298-305. [PMID: 31626711 DOI: 10.1002/jbmr.3900] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 10/01/2019] [Accepted: 10/15/2019] [Indexed: 12/19/2022]
Abstract
Preclinical studies on the role of erythropoietin (EPO) in bone metabolism are contradictory. Regeneration models indicate an anabolic effect on bone healing, whereas models on physiologic bone remodeling indicate a catabolic effect on bone mass. No human studies on EPO and fracture risk are available. It is known that fibroblast growth factor 23 (FGF23) affects bone mineralization and that serum concentration of FGF23 is higher in men with decreased estimated glomerular filtration rate (eGFR). Recently, a direct association between EPO and FGF23 has been shown. We have explored the potential association between EPO and bone mineral density (BMD), fracture risk, and FGF23 in humans. Plasma levels of EPO were analyzed in 999 men (aged 69 to 81 years), participating in the Gothenburg part of the population-based Osteoporotic Fractures in Men (MrOS) study, MrOS Sweden. The mean ± SD EPO was 11.5 ± 9.0 IU/L. Results were stratified by eGFR 60 mL/min. For men with eGFR ≥60 mL/min (n = 728), EPO was associated with age (r = 0.13, p < 0.001), total hip BMD (r = 0.14, p < 0.001), intact (i)FGF23 (r = 0.11, p = 0.004), and osteocalcin (r = -0.09, p = 0.022). The association between total hip BMD and EPO was independent of age, body mass index (BMI), iFGF23, and hemoglobin (beta = 0.019, p < 0.001). During the 10-year follow-up, 164 men had an X-ray-verified fracture, including 117 major osteoporotic fractures (MOF), 39 hip fractures, and 64 vertebral fractures. High EPO was associated with higher risk for incident fractures (hazard ratio [HR] = 1.43 per tertile EPO, 95% confidence interval [CI] 1.35-1.63), MOF (HR = 1.40 per tertile EPO, 95% CI 1.08-1.82), and vertebral fractures (HR = 1.42 per tertile EPO, 95% CI 1.00-2.01) in a fully adjusted Cox regression model. In men with eGFR<60 mL/min, no association was found between EPO and BMD or fracture risk. We here demonstrate that high levels of EPO are associated with increased fracture risk and increased BMD in elderly men with normal renal function. © 2019 American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Hallgerdur Lind Kristjansdottir
- Department of Hematology and Coagulation, Sahlgrenska University Hospital and Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Catharina Lewerin
- Department of Hematology and Coagulation, Sahlgrenska University Hospital and Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ulf H Lerner
- Centre for Bone and Arthritis Research, Department of Internal Medicine and Clinical Nutrition, Institute for Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Hans Herlitz
- Department of Molecular and Clinical Medicine/Nephrology, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Peter Johansson
- Department of Hematology and Coagulation, Sahlgrenska University Hospital and Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Helena Johansson
- McKillop Health Institute, Australian Catholic University, Melbourne, Australia.,Department of Public Health and Community Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Magnus Karlsson
- Department of Orthopedics and Clinical Sciences, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Mattias Lorentzon
- McKillop Health Institute, Australian Catholic University, Melbourne, Australia.,Department of Geriatric Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden.,Geriatric Medicine, Department of Internal Medicine and Clinical Nutrition, Institute of Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Claes Ohlsson
- Centre for Bone and Arthritis Research, Department of Internal Medicine and Clinical Nutrition, Institute for Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Östen Ljunggren
- Department of Medical Sciences, University of Uppsala, Uppsala, Sweden
| | - Dan Mellström
- Centre for Bone and Arthritis Research, Department of Internal Medicine and Clinical Nutrition, Institute for Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Department of Geriatric Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden.,Geriatric Medicine, Department of Internal Medicine and Clinical Nutrition, Institute of Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
34
|
Agoro R, Ni P, Noonan ML, White KE. Osteocytic FGF23 and Its Kidney Function. Front Endocrinol (Lausanne) 2020; 11:592. [PMID: 32982979 PMCID: PMC7485387 DOI: 10.3389/fendo.2020.00592] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 07/20/2020] [Indexed: 12/16/2022] Open
Abstract
Osteocytes, which represent up to 95% of adult skeletal cells, are deeply embedded in bone. These cells exhibit important interactive abilities with other bone cells such as osteoblasts and osteoclasts to control skeletal formation and resorption. Beyond this local role, osteocytes can also influence the function of distant organs due to the presence of their sophisticated lacunocanalicular system, which connects osteocyte dendrites directly to the vasculature. Through these networks, osteocytes sense changes in circulating metabolites and respond by producing endocrine factors to control homeostasis. One critical function of osteocytes is to respond to increased blood phosphate and 1,25(OH)2 vitamin D (1,25D) by producing fibroblast growth factor-23 (FGF23). FGF23 acts on the kidneys through partner fibroblast growth factor receptors (FGFRs) and the co-receptor Klotho to promote phosphaturia via a downregulation of phosphate transporters, as well as the control of vitamin D metabolizing enzymes to reduce blood 1,25D. In the first part of this review, we will explore the signals involved in the positive and negative regulation of FGF23 in osteocytes. In the second portion, we will bridge bone responses with the review of current knowledge on FGF23 endocrine functions in the kidneys.
Collapse
Affiliation(s)
- Rafiou Agoro
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Pu Ni
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Megan L. Noonan
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Kenneth E. White
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States
- Medicine/Division of Nephrology, Indiana University School of Medicine, Indianapolis, IN, United States
- *Correspondence: Kenneth E. White
| |
Collapse
|
35
|
Lee SM, Carlson AH, Onal M, Benkusky NA, Meyer MB, Pike JW. A Control Region Near the Fibroblast Growth Factor 23 Gene Mediates Response to Phosphate, 1,25(OH)2D3, and LPS In Vivo. Endocrinology 2019; 160:2877-2891. [PMID: 31599948 PMCID: PMC6850268 DOI: 10.1210/en.2019-00622] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/04/2019] [Indexed: 12/21/2022]
Abstract
Fibroblast growth factor 23 (FGF23) is a bone-derived hormone involved in the control of phosphate (P) homeostasis and vitamin D metabolism. Despite advances, however, molecular details of this gene's regulation remain uncertain. In this report, we created mouse strains in which four epigenetically marked FGF23 regulatory regions were individually deleted from the mouse genome using CRISPR/Cas9 gene-editing technology, and the consequences of these mutations were then assessed on Fgf23 expression and regulation in vivo. An initial analysis confirmed that bone expression of Fgf23 and circulating intact FGF23 (iFGF23) were strongly influenced by both chronic dietary P treatment and acute injection of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. However, further analysis revealed that bone Fgf23 expression and iFGF23 could be rapidly upregulated by dietary P within 3 and 6 hours, respectively; this acute upregulation was lost in the FGF23-PKO mouse containing an Fgf23 proximal enhancer deletion but not in the additional enhancer-deleted mice. Of note, prolonged dietary P treatment over several days led to normalization of FGF23 levels in the FGF23-PKO mouse, suggesting added complexity associated with P regulation of FGF23. Treatment with 1,25(OH)2D3 also revealed a similar loss of Fgf23 induction and blood iFGF23 levels in this mouse. Finally, normal lipopolysaccharide (LPS) induction of Fgf23 expression was also compromised in the FGF23-PKO mouse, a result that, together with our previous report, indicates that the action of LPS on Fgf23 expression is mediated by both proximal and distal Fgf23 enhancers. These in vivo data provide key functional insight into the genomic enhancers through which Fgf23 expression is mediated.
Collapse
Affiliation(s)
- Seong Min Lee
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin
| | - Alex H Carlson
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin
| | - Melda Onal
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin
| | - Nancy A Benkusky
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin
| | - Mark B Meyer
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin
| | - J Wesley Pike
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin
- Correspondence: J. Wesley Pike, PhD, Department of Biochemistry, University of Wisconsin–Madison, Hector F. Deluca Laboratories, Room 543D, 433 Babcock Drive, Madison, Wisconsin 53706. E-mail:
| |
Collapse
|
36
|
Christakos S, Li S, De La Cruz J, Bikle DD. New developments in our understanding of vitamin metabolism, action and treatment. Metabolism 2019; 98:112-120. [PMID: 31226354 PMCID: PMC6814307 DOI: 10.1016/j.metabol.2019.06.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 06/07/2019] [Accepted: 06/14/2019] [Indexed: 12/14/2022]
Abstract
Although vitamin D has been reported to have pleiotropic effects including effects on the immune system and on cancer progression, the principal action of vitamin D is the maintenance of calcium and phosphate homeostasis. The importance of vitamin D in this process is emphasized by the consequences of vitamin D deficiency which includes rickets in children and osteomalacia in adults. Vitamin D deficiency has also been reported to increase the risk of falls and osteoporotic fractures. Although vitamin D fortification of foods (including dairy products) has contributed to a marked decrease in rickets in the Western world, vitamin D deficiency in children and adults is still prevalent world-wide. This review summarizes new developments in our understanding of vitamin D endocrine system and addresses clinical syndromes related to abnormalities in vitamin D metabolism and action. In addition, the current understanding of the evaluation of vitamin D deficiency and sufficiency and recommendations for achieving vitamin D sufficiency are discussed.
Collapse
Affiliation(s)
- Sylvia Christakos
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, the State University of New Jersey, New Jersey Medical School, Newark, NJ, USA.
| | - Shanshan Li
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, the State University of New Jersey, New Jersey Medical School, Newark, NJ, USA
| | - Jessica De La Cruz
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers, the State University of New Jersey, New Jersey Medical School, Newark, NJ, USA
| | - Daniel D Bikle
- Departments of Medicine and Dermatology, University of California and VA Medical Center, San Francisco, CA, USA
| |
Collapse
|
37
|
Czaya B, Faul C. The Role of Fibroblast Growth Factor 23 in Inflammation and Anemia. Int J Mol Sci 2019; 20:E4195. [PMID: 31461904 PMCID: PMC6747522 DOI: 10.3390/ijms20174195] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/22/2019] [Accepted: 08/23/2019] [Indexed: 02/07/2023] Open
Abstract
In patients with chronic kidney disease (CKD), adverse outcomes such as systemic inflammation and anemia are contributing pathologies which increase the risks for cardiovascular mortality. Amongst these complications, abnormalities in mineral metabolism and the metabolic milieu are associated with chronic inflammation and iron dysregulation, and fibroblast growth factor 23 (FGF23) is a risk factor in this context. FGF23 is a bone-derived hormone that is essential for regulating vitamin D and phosphate homeostasis. In the early stages of CKD, serum FGF23 levels rise 1000-fold above normal values in an attempt to maintain normal phosphate levels. Despite this compensatory action, clinical CKD studies have demonstrated powerful and dose-dependent associations between FGF23 levels and higher risks for mortality. A prospective pathomechanism coupling elevated serum FGF23 levels with CKD-associated anemia and cardiovascular injury is its strong association with chronic inflammation. In this review, we will examine the current experimental and clinical evidence regarding the role of FGF23 in renal physiology as well as in the pathophysiology of CKD with an emphasis on chronic inflammation and anemia.
Collapse
Affiliation(s)
- Brian Czaya
- Division of Nephrology, Department of Medicine, The University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Christian Faul
- Division of Nephrology, Department of Medicine, The University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| |
Collapse
|
38
|
Fibroblast growth factor 23 and α-Klotho co-dependent and independent functions. Curr Opin Nephrol Hypertens 2019; 28:16-25. [PMID: 30451736 DOI: 10.1097/mnh.0000000000000467] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
PURPOSE OF REVIEW The current review examines what is known about the FGF-23/α-Klotho co-dependent and independent pathophysiological effects, and whether FGF-23 and/or α-Klotho are potential therapeutic targets. RECENT FINDINGS FGF-23 is a hormone derived mainly from bone, and α-Klotho is a transmembrane protein. Together they form a trimeric signaling complex with FGFRs in target tissues to mediate the physiological functions of FGF-23. Local and systemic factors control FGF-23 release from osteoblast/osteocytes in bone, and circulating FGF-23 activates FGFR/α-Klotho complexes in kidney proximal and distal renal tubules to regulate renal phosphate excretion, 1,25 (OH)2D metabolism, sodium and calcium reabsorption, and ACE2 and α-Klotho expression. The resulting bone-renal-cardiac-immune networks provide a new understanding of bone and mineral homeostasis, as well as identify other biological effects FGF-23. Direct FGF-23 activation of FGFRs in the absence of α-Klotho is proposed to mediate cardiotoxic and adverse innate immune effects of excess FGF-23, particularly in chronic kidney disease, but this FGF-23, α-Klotho-independent signaling is controversial. In addition, circulating soluble Klotho (sKl) released from the distal tubule by ectodomain shedding is proposed to have beneficial health effects independent of FGF-23. SUMMARY Separation of FGF-23 and α-Klotho independent functions has been difficult in mammalian systems and understanding FGF-23/α-Klotho co-dependent and independent effects are incomplete. Antagonism of FGF-23 is important in treatment of hypophosphatemic disorders caused by excess FGF-23, but its role in chronic kidney disease is uncertain. Administration of recombinant sKl is an unproven therapeutic strategy that theoretically could improve the healt span and lifespan of patients with α-Klotho deficiency.
Collapse
|
39
|
Abstract
PURPOSE OF REVIEW An elevated level of pro-inflammatory cytokines in inflammatory conditions causes bone loss and disrupts vital organ function. Osteocytes comprise > 95% of the cellular component in bone tissue, produce a range of cytokines and signaling molecules, and influence bone and other organ function. In this review, we hypothesized that an elevated level of pro-inflammatory cytokines in inflammatory conditions affects osteocyte survival and function thereby possibly amplifying inflammation, and causing bone loss and non-bone clinical complications. RECENT FINDINGS Several studies have reported that the elevated level of pro-inflammatory cytokines in inflammatory conditions alters osteocyte mechanosensitivity, causes osteocyte apoptosis, and modulates osteocyte-derived production of various inflammatory cytokines and signaling molecules. Cytokines and signaling molecules released from osteocytes affect surrounding bone cells and distant organ function in a paracrine and endocrine fashion. Inflammatory diseases including diabetes, chronic kidney disease, rheumatoid arthritis, and periodontitis affect osteocyte survival and function, and upregulate osteocyte-derived expression of sclerostin, RANKL, TNFα, FGF23, DKK1, and other signaling molecules.
Collapse
Affiliation(s)
- Miao Zhou
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Affiliated Stomatology Hospital of Guangzhou Medical University, Huangsha Avenue 39, Guangzhou, 510140, China
| | - Shuyi Li
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Affiliated Stomatology Hospital of Guangzhou Medical University, Huangsha Avenue 39, Guangzhou, 510140, China
| | - Janak L Pathak
- Key Laboratory of Oral Medicine, Guangzhou Institute of Oral Disease, Affiliated Stomatology Hospital of Guangzhou Medical University, Huangsha Avenue 39, Guangzhou, 510140, China.
| |
Collapse
|
40
|
Egli-Spichtig D, Imenez Silva PH, Glaudemans B, Gehring N, Bettoni C, Zhang MYH, Pastor-Arroyo EM, Schönenberger D, Rajski M, Hoogewijs D, Knauf F, Misselwitz B, Frey-Wagner I, Rogler G, Ackermann D, Ponte B, Pruijm M, Leichtle A, Fiedler GM, Bochud M, Ballotta V, Hofmann S, Perwad F, Föller M, Lang F, Wenger RH, Frew I, Wagner CA. Tumor necrosis factor stimulates fibroblast growth factor 23 levels in chronic kidney disease and non-renal inflammation. Kidney Int 2019; 96:890-905. [PMID: 31301888 DOI: 10.1016/j.kint.2019.04.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 03/11/2019] [Accepted: 04/05/2019] [Indexed: 01/03/2023]
Abstract
Fibroblast growth factor 23 (FGF23) regulates phosphate homeostasis, and its early rise in patients with chronic kidney disease is independently associated with all-cause mortality. Since inflammation is characteristic of chronic kidney disease and associates with increased plasma FGF23 we examined whether inflammation directly stimulates FGF23. In a population-based cohort, plasma tumor necrosis factor (TNF) was the only inflammatory cytokine that independently and positively correlated with plasma FGF23. Mouse models of chronic kidney disease showed signs of renal inflammation, renal FGF23 expression and elevated systemic FGF23 levels. Renal FGF23 expression coincided with expression of the orphan nuclear receptor Nurr1 regulating FGF23 in other organs. Antibody-mediated neutralization of TNF normalized plasma FGF23 and suppressed ectopic renal Fgf23 expression. Conversely, TNF administration to control mice increased plasma FGF23 without altering plasma phosphate. Moreover, in Il10-deficient mice with inflammatory bowel disease and normal kidney function, plasma FGF23 was elevated and normalized upon TNF neutralization. Thus, the inflammatory cytokine TNF contributes to elevated systemic FGF23 levels and also triggers ectopic renal Fgf23 expression in animal models of chronic kidney disease.
Collapse
Affiliation(s)
- Daniela Egli-Spichtig
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland; Department of Pediatrics, Division of Nephrology, University of California, San Francisco, San Francisco, California, USA
| | - Pedro Henrique Imenez Silva
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland
| | - Bob Glaudemans
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland
| | - Nicole Gehring
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland
| | - Carla Bettoni
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland
| | - Martin Y H Zhang
- Department of Pediatrics, Division of Nephrology, University of California, San Francisco, San Francisco, California, USA
| | - Eva M Pastor-Arroyo
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland
| | - Désirée Schönenberger
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland
| | - Michal Rajski
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland
| | - David Hoogewijs
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland
| | - Felix Knauf
- Division of Nephrology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Benjamin Misselwitz
- University Hospital Zurich, Clinic for Gastroenterology and Hepatology, Zurich, Switzerland
| | - Isabelle Frey-Wagner
- University Hospital Zurich, Clinic for Gastroenterology and Hepatology, Zurich, Switzerland
| | - Gerhard Rogler
- University Hospital Zurich, Clinic for Gastroenterology and Hepatology, Zurich, Switzerland
| | - Daniel Ackermann
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Belen Ponte
- Department of Nephrology, University Hospital of Geneva (HUG), Geneva, Switzerland
| | - Menno Pruijm
- Department of Nephrology, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Alexander Leichtle
- Institute of Clinical Chemistry, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Georg-Martin Fiedler
- Institute of Clinical Chemistry, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Murielle Bochud
- Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland; Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Virginia Ballotta
- Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Sandra Hofmann
- Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Farzana Perwad
- Department of Pediatrics, Division of Nephrology, University of California, San Francisco, San Francisco, California, USA
| | - Michael Föller
- Institute of Physiology, University of Hohenheim, Stuttgart, Germany
| | - Florian Lang
- Institute of Physiology I, University of Tübingen, Tübingen, Germany
| | - Roland H Wenger
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland
| | - Ian Frew
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Swiss National Center of Competence in Research NCCR-Kidney.CH, University of Zurich, Zurich, Switzerland.
| |
Collapse
|
41
|
Abstract
PURPOSE OF REVIEW The phosphaturic hormone FGF23 is produced primarily in osteoblasts/osteocytes and is known to respond to increases in serum phosphate and 1,25(OH)2 vitamin D (1,25D). Novel regulators of FGF23 were recently identified, and may help explain the pathophysiologies of several diseases. This review will focus on recent studies examining the synthesis and actions of FGF23. RECENT FINDINGS The synthesis of FGF23 in response to 1,25D is similar to other steroid hormone targets, but the cellular responses to phosphate remain largely unknown. The activity of intracellular processing genes control FGF23 glycosylation and phosphorylation, providing critical functions in determining the serum levels of bioactive FGF23. The actions of FGF23 largely occur through its co-receptor αKlotho (KL) under normal circumstances, but FGF23 has KL-independent activity during situations of high concentrations. SUMMARY Recent work regarding FGF23 synthesis and bioactivity, as well as considerations for diseases of altered phosphate balance will be reviewed.
Collapse
Affiliation(s)
- Megan L Noonan
- Department of Medical & Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Kenneth E White
- Department of Medical & Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| |
Collapse
|
42
|
Renal ischemia-reperfusion injury impairs renal calcium, magnesium, and phosphate handling in mice. Pflugers Arch 2019; 471:901-914. [PMID: 30685787 DOI: 10.1007/s00424-019-02255-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/04/2019] [Accepted: 01/10/2019] [Indexed: 01/04/2023]
Abstract
Fibroblast growth factor 23 (FGF23) levels are elevated in patients with acute kidney injury (AKI). The consequences on renal Ca2+, Mg2+, and Pi regulatory mechanisms are unknown. We hypothesized that renal ischemia-reperfusion (I/R) injury alters the expression of important renal Ca2+, Mg2+, and Pi transport proteins. I/R injury was induced in male C57BL/6 mice by clamping both renal arteries for 27 min. Mice were investigated 18 h later. The mRNA and protein levels of renal Ca2+, Mg2+, and Pi transport proteins were measured by RT-qPCR and western blot analysis. I/R injury-induced hyperphosphatemia and hypermagnesemia were paralleled by a decrease in glomerular filtration rate and an increase in the fractional excretion of Ca2+, Mg2+, and Pi. I/R injury affected the fibroblast growth factor 23 (FGF23)-klotho-vitamin D axis by increasing plasma levels of FGF23 and downregulation of renal klotho expression. Plasma levels of PTH and 1,25-dihydroxyvitamin D3 were unchanged. Further, downregulation of key genes for paracellular reabsorption of Ca2+ and Mg2+ (claudin (Cldn)2, Cldn10b, Cldn16, Cldn19) and for active transcellular transport of Ca2+, Mg2+, and Pi (calbindin-D28K, Ncx1, Pmca4, Cnnm2, Trpm7, NaPi-2a, and NaPi-2c) was observed. However, renal expression of Trpv5 and Trpv6 was increased. In vitro studies support a direct effect of proinflammatory cytokines on the mRNA expression of Cldn16, Cldn19, and Trpv6. Our findings indicate that renal I/R injury increases FGF23 blood levels independent of PTH and 1,25-dihydroxyvitamin D3. This increase is associated with hypermagnesemia, hyperphosphatemia, and increased or decreased expression of specific renal Ca2+, Mg2+, and Pi transporters, respectively.
Collapse
|
43
|
Wheeler JA, Clinkenbeard EL. Regulation of Fibroblast Growth Factor 23 by Iron, EPO, and HIF. ACTA ACUST UNITED AC 2019; 5:8-17. [PMID: 31218207 DOI: 10.1007/s40610-019-0110-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Purpose of review Fibroblast growth factor-23 (FGF23) is the key hormone produced in bone critical for phosphate homeostasis. Elevated serum phosphorus and 1,25dihydroxyvitaminD stimulates FGF23 production to promote renal phosphate excretion and decrease 1,25dihydroxyvitaminD synthesis. Thus completing the feedback loop and suppressing FGF23. Unexpectedly, studies of common and rare heritable disorders of phosphate handling identified links between iron and FGF23 demonstrating novel regulation outside the phosphate pathway. Recent Findings Iron deficiency combined with an FGF23 cleavage mutation was found to induce the autosomal dominant hypophosphatemic rickets phenotype. Physiological responses to iron deficiency, such as erythropoietin production as well as hypoxia inducible factor activation, have been indicated in regulating FGF23. Additionally, specific iron formulations, used to treat iron deficiency, alter post-translational processing thereby shifting FGF23 protein secretion. Summary Molecular and clinical studies revealed that iron deficiency, through several mechanisms, alters FGF23 at the transcriptional and post-translational level. This review will focus upon the novel discoveries elucidated between iron, its regulators, and their influence on FGF23 bioactivity.
Collapse
Affiliation(s)
- Jonathan A Wheeler
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Erica L Clinkenbeard
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| |
Collapse
|
44
|
Meurer M, Höcherl K. Endotoxaemia differentially regulates the expression of renal Ca 2+ transport proteins in mice. Acta Physiol (Oxf) 2019; 225:e13175. [PMID: 30133162 DOI: 10.1111/apha.13175] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 08/17/2018] [Accepted: 08/18/2018] [Indexed: 12/16/2022]
Abstract
AIM Alterations in parathyroid hormone (PTH) and/or vitamin D signalling are frequently reported in patients with sepsis. The consequences on renal and intestinal Ca2+ and Pi regulatory mechanisms are still unclear. We hypothesized that endotoxaemia alters the expression of important renal and intestinal Ca2+ and Pi transport proteins. METHODS Male C57BL/6 mice were treated with lipopolysaccharide (LPS; 3 mg/kg; i.p.). The mRNA and protein levels of renal and intestinal Ca2+ and Pi transport proteins were measured by RT-qPCR, immunohistochemistry and western blot analysis. RESULTS Lipopolysaccharide-induced hypocalcaemia and hyperphosphataemia was paralleled by a decrease in glomerular filtration rate and urinary excretion of Ca2+ and Pi . Endotoxaemia augmented plasma levels of PTH and affected the fibroblast growth factor 23 (FGF23)-klotho-vitamin D axis by increasing plasma levels of FGF23 and downregulation of renal klotho expression. Renal expression of CYP27b1 and plasma levels of 1,25-dihydroxyvitamin D3 were increased in response to LPS. Endotoxaemia augmented the renal expression of TRPV5, TRPV6 and PiT1, whereas the renal expression of calbindin-D28K , NCX1, NaPi -2a and NaPi -2c were decreased. Incubation of primary distal tubule cells with LPS increased TRPV6 mRNA levels. Furthermore, LPS decreased the intestinal expression of TRPV6, calbindin-D9K and of NaPi -2b. CONCLUSION Our findings indicate that endotoxaemia is associated with hypocalcaemia and hyperphosphataemia and a disturbed FGF23-klotho-vitamin D signaling. Further, LPS-induced acute kidney injury was accompanied by an increased or decreased expression of specific renal and intestinal Ca2+ and Pi transporters respectively. It seems unlikely that LPS-induced hypocalcaemia is due to renal loss of Ca2+ .
Collapse
Affiliation(s)
- Manuel Meurer
- Institute of Experimental and Clinical Pharmacology and Toxicology; Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU); Erlangen Germany
| | - Klaus Höcherl
- Institute of Experimental and Clinical Pharmacology and Toxicology; Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU); Erlangen Germany
| |
Collapse
|
45
|
Abstract
Inorganic phosphate (Pi) is essential for signal transduction and cell metabolism, and is also an essential structural component of the extracellular matrix of the skeleton. Pi is sensed in bacteria and yeast at the plasma membrane, which activates intracellular signal transduction to control the expression of Pi transporters and other genes that control intracellular Pi levels. In multicellular organisms, Pi homeostasis must be maintained in the organism and at the cellular level, requiring an endocrine and metabolic Pi-sensing mechanism, about which little is currently known. This Review will discuss the metabolic effects of Pi, which are mediated by Pi transporters, inositol pyrophosphates and SYG1-Pho81-XPR1 (SPX)-domain proteins to maintain cellular phosphate homeostasis in the musculoskeletal system. In addition, we will discuss how Pi is sensed by the human body to regulate the production of fibroblast growth factor 23 (FGF23), parathyroid hormone and calcitriol to maintain serum levels of Pi in a narrow range. New findings on the crosstalk between iron and Pi homeostasis in the regulation of FGF23 expression will also be outlined. Mutations in components of these metabolic and endocrine phosphate sensors result in genetic disorders of phosphate homeostasis, cardiomyopathy and familial basal ganglial calcifications, highlighting the importance of this newly emerging area of research.
Collapse
Affiliation(s)
- Sampada Chande
- Section of Endocrinology and Metabolism, Yale University School of Medicine, New Haven, CT, USA
| | - Clemens Bergwitz
- Section of Endocrinology and Metabolism, Yale University School of Medicine, New Haven, CT, USA.
| |
Collapse
|
46
|
Fitzpatrick EA, Han X, Xiao Z, Quarles LD. Role of Fibroblast Growth Factor-23 in Innate Immune Responses. Front Endocrinol (Lausanne) 2018; 9:320. [PMID: 29946298 PMCID: PMC6005851 DOI: 10.3389/fendo.2018.00320] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 05/28/2018] [Indexed: 01/29/2023] Open
Abstract
Fibroblast growth factor-23 (FGF-23) is a bone-derived hormone that activates FGFR/α-Klotho binary complexes in the kidney renal tubules to regulate phosphate reabsorption and vitamin D metabolism. The objective of this review is to discuss the emerging data that show that FGF-23 has functions beyond regulation of mineral metabolism, including roles in innate immune and hemodynamic responses. Excess FGF-23 is associated with inflammation and adverse infectious outcomes, as well as increased morbidity and mortality, particularly in patients with chronic kidney disease. Enhancer elements in the FGF-23 promoter have been identified that mediate the effects of inflammatory cytokines to stimulate FGF-23 gene transcription in bone. In addition, inflammation induces ectopic expression of FGF-23 and α-Klotho in macrophages that do not normally express FGF-23 or its binary receptor complexes. These observations suggest that FGF-23 may play an important role in regulating innate immunity through multiple potential mechanisms. Circulating FGF-23 acts as a counter-regulatory hormone to suppress 1,25D production in the proximal tubule of the kidney. Since vitamin D deficiency may predispose infectious and cardiovascular diseases, FGF-23 effects on innate immune responses may be due to suppression of 1,25D production. Alternatively, systemic and locally produced FGF-23 may modulate immune functions through direct interactions with myeloid cells, including macrophages and polymorphonuclear leukocytes to impair immune cell functions. Short-acting small molecules that reversibly inhibit FGF-23 offer the potential to block pro-inflammatory and cardiotoxic effects of FGF-23 with less side effects compared with FGF-23 blocking antibodies that have the potential to cause hyperphosphatemia and soft tissue calcifications in animal models. In conclusion, there are several mechanisms by which FGF-23 impacts the innate immune system and further investigation is critical for the development of therapies to treat diseases associated with elevated FGF-23.
Collapse
Affiliation(s)
- Elizabeth A. Fitzpatrick
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Xiaobin Han
- Department of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Zhousheng Xiao
- Department of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
| | - L. Darryl Quarles
- Department of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
- *Correspondence: L. Darryl Quarles,
| |
Collapse
|