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Wagner CA. The basics of phosphate metabolism. Nephrol Dial Transplant 2024; 39:190-201. [PMID: 37660247 PMCID: PMC10828206 DOI: 10.1093/ndt/gfad188] [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: 07/14/2023] [Indexed: 09/04/2023] Open
Abstract
Phosphorus is an essential mineral that is, in the form of inorganic phosphate (Pi), required for building cell membranes, DNA and RNA molecules, energy metabolism, signal transduction and pH buffering. In bone, Pi is essential for bone stability in the form of apatite. Intestinal absorption of dietary Pi depends on its bioavailability and has two distinct modes of active transcellular and passive paracellular absorption. Active transport is transporter mediated and partly regulated, while passive absorption depends mostly on bioavailability. Renal excretion controls systemic Pi levels, depends on transporters in the proximal tubule and is highly regulated. Deposition and release of Pi into and from soft tissues and bone has to be tightly controlled. The endocrine network coordinating intestinal absorption, renal excretion and bone turnover integrates dietary intake and metabolic requirements with renal excretion and is critical for bone stability and cardiovascular health during states of hypophosphataemia or hyperphosphataemia as evident from inborn or acquired diseases. This review provides an integrated overview of the biology of phosphate and Pi in mammals.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
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2
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Abstract
Inorganic phosphate (Pi) is an essential component of many biologically important molecules such as DNA, RNA, ATP, phospholipids, or apatite. It is required for intracellular phosphorylation signaling events and acts as pH buffer in intra- and extracellular compartments. Intestinal absorption, uptake into cells, and renal reabsorption depend on a set of different phosphate transporters from the SLC20 (PiT transporters) and SLC34 (NaPi transporters) gene families. The physiological relevance of these transporters is evident from rare monogenic disorders in humans affecting SLC20A2 (Fahr's disease, basal ganglia calcification), SLC34A1 (idiopathic infantile hypercalcemia), SLC34A2 (pulmonary alveolar microlithiasis), and SLC34A3 (hereditary hypophosphatemic rickets with hypercalciuria). SLC34 transporters are inhibited by millimolar concentrations of phosphonoformic acid or arsenate while SLC20 are relatively resistant to these compounds. More recently, a series of more specific and potent drugs have been developed to target SLC34A2 to reduce intestinal Pi absorption and to inhibit SLC34A1 and/or SLC34A3 to increase renal Pi excretion in patients with renal disease and incipient hyperphosphatemia. Also, SLC20 inhibitors have been developed with the same intention. Some of these substances are currently undergoing preclinical and clinical testing. Tenapanor, a non-absorbable Na+/H+-exchanger isoform 3 inhibitor, reduces intestinal Pi absorption likely by indirectly acting on the paracellular pathway for Pi and has been tested in several phase III trials for reducing Pi overload in patients with renal insufficiency and dialysis.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.
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3
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Machado A, Pouzolles M, Gailhac S, Fritz V, Craveiro M, López-Sánchez U, Kondo T, Pala F, Bosticardo M, Notarangelo LD, Petit V, Taylor N, Zimmermann VS. Phosphate Transporter Profiles in Murine and Human Thymi Identify Thymocytes at Distinct Stages of Differentiation. Front Immunol 2020; 11:1562. [PMID: 32793218 PMCID: PMC7387685 DOI: 10.3389/fimmu.2020.01562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/15/2020] [Indexed: 12/22/2022] Open
Abstract
Thymocyte differentiation is dependent on the availability and transport of metabolites in the thymus niche. As expression of metabolite transporters is a rate-limiting step in nutrient utilization, cell surface transporter levels generally reflect the cell's metabolic state. The GLUT1 glucose transporter is upregulated on actively dividing thymocytes, identifying thymocytes with an increased metabolism. However, it is not clear whether transporters of essential elements such as phosphate are modulated during thymocyte differentiation. While PiT1 and PiT2 are both phosphate transporters in the SLC20 family, we show here that they exhibit distinct expression profiles on both murine and human thymocytes. PiT2 expression distinguishes thymocytes with high metabolic activity, identifying immature murine double negative (CD4−CD8−) DN3b and DN4 thymocyte blasts as well as immature single positive (ISP) CD8 thymocytes. Notably, the absence of PiT2 expression on RAG2-deficient thymocytes, blocked at the DN3a stage, strongly suggests that high PiT2 expression is restricted to thymocytes having undergone a productive TCRβ rearrangement at the DN3a/DN3b transition. Similarly, in the human thymus, PiT2 was upregulated on early post-β selection CD4+ISP and TCRαβ−CD4hiDP thymocytes co-expressing the CD71 transferrin receptor, a marker of metabolic activity. In marked contrast, expression of the PiT1 phosphate importer was detected on mature CD3+ murine and human thymocytes. Notably, PiT1 expression on CD3+DN thymocytes was identified as a biomarker of an aging thymus, increasing from 8.4 ± 1.5% to 42.4 ± 9.4% by 1 year of age (p < 0.0001). We identified these cells as TCRγδ and, most significantly, NKT, representing 77 ± 9% of PiT1+DN thymocytes by 1 year of age (p < 0.001). Thus, metabolic activity and thymic aging are associated with distinct expression profiles of the PiT1 and PiT2 phosphate transporters.
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Affiliation(s)
- Alice Machado
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health (NIH), Bethesda, MD, United States.,Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Marie Pouzolles
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health (NIH), Bethesda, MD, United States
| | - Sarah Gailhac
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Vanessa Fritz
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Marco Craveiro
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Uriel López-Sánchez
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Taisuke Kondo
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health (NIH), Bethesda, MD, United States
| | - Francesca Pala
- Laboratory of Clinical Immunology and Microbiology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, United States
| | - Marita Bosticardo
- Laboratory of Clinical Immunology and Microbiology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, United States
| | - Luigi D Notarangelo
- Laboratory of Clinical Immunology and Microbiology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, United States
| | | | - Naomi Taylor
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health (NIH), Bethesda, MD, United States.,Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Valérie S Zimmermann
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health (NIH), Bethesda, MD, United States.,Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
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4
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Abstract
Phosphate is an essential nutrient for life and is a critical component of bone formation, a major signaling molecule, and structural component of cell walls. Phosphate is also a component of high-energy compounds (i.e., AMP, ADP, and ATP) and essential for nucleic acid helical structure (i.e., RNA and DNA). Phosphate plays a central role in the process of mineralization, normal serum levels being associated with appropriate bone mineralization, while high and low serum levels are associated with soft tissue calcification. The serum concentration of phosphate and the total body content of phosphate are highly regulated, a process that is accomplished by the coordinated effort of two families of sodium-dependent transporter proteins. The three isoforms of the SLC34 family (SLC34A1-A3) show very restricted tissue expression and regulate intestinal absorption and renal excretion of phosphate. SLC34A2 also regulates the phosphate concentration in multiple lumen fluids including milk, saliva, pancreatic fluid, and surfactant. Both isoforms of the SLC20 family exhibit ubiquitous expression (with some variation as to which one or both are expressed), are regulated by ambient phosphate, and likely serve the phosphate needs of the individual cell. These proteins exhibit similarities to phosphate transporters in nonmammalian organisms. The proteins are nonredundant as mutations in each yield unique clinical presentations. Further research is essential to understand the function, regulation, and coordination of the various phosphate transporters, both the ones described in this review and the phosphate transporters involved in intracellular transport.
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Affiliation(s)
- Nati Hernando
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Kenneth Gagnon
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Eleanor Lederer
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
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5
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Zhang R, Saredy J, Shao Y, Yao T, Liu L, Saaoud F, Yang WY, Sun Y, Johnson C, Drummer C, Fu H, Lu Y, Xu K, Liu M, Wang J, Cutler E, Yu D, Jiang X, Li Y, Li R, Wang L, Choi ET, Wang H, Yang X. End-stage renal disease is different from chronic kidney disease in upregulating ROS-modulated proinflammatory secretome in PBMCs - A novel multiple-hit model for disease progression. Redox Biol 2020; 34:101460. [PMID: 32179051 PMCID: PMC7327976 DOI: 10.1016/j.redox.2020.101460] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/28/2020] [Accepted: 02/07/2020] [Indexed: 12/17/2022] Open
Abstract
Background The molecular mechanisms underlying chronic kidney disease (CKD) transition to end-stage renal disease (ESRD) and CKD acceleration of cardiovascular and other tissue inflammations remain poorly determined. Methods We conducted a comprehensive data analyses on 7 microarray datasets in peripheral blood mononuclear cells (PBMCs) from patients with CKD and ESRD from NCBI-GEO databases, where we examined the expressions of 2641 secretome genes (SG). Results 1) 86.7% middle class (molecular weight >500 Daltons) uremic toxins (UTs) were encoded by SGs; 2) Upregulation of SGs in PBMCs in patients with ESRD (121 SGs) were significantly higher than that of CKD (44 SGs); 3) Transcriptomic analyses of PBMC secretome had advantages to identify more comprehensive secretome than conventional secretomic analyses; 4) ESRD-induced SGs had strong proinflammatory pathways; 5) Proinflammatory cytokines-based UTs such as IL-1β and IL-18 promoted ESRD modulation of SGs; 6) ESRD-upregulated co-stimulation receptors CD48 and CD58 increased secretomic upregulation in the PBMCs, which were magnified enormously in tissues; 7) M1-, and M2-macrophage polarization signals contributed to ESRD- and CKD-upregulated SGs; 8) ESRD- and CKD-upregulated SGs contained senescence-promoting regulators by upregulating proinflammatory IGFBP7 and downregulating anti-inflammatory TGF-β1 and telomere stabilizer SERPINE1/PAI-1; 9) ROS pathways played bigger roles in mediating ESRD-upregulated SGs (11.6%) than that in CKD-upregulated SGs (6.8%), and half of ESRD-upregulated SGs were ROS-independent. Conclusions Our analysis suggests novel secretomic upregulation in PBMCs of patients with CKD and ESRD, act synergistically with uremic toxins, to promote inflammation and potential disease progression. Our findings have provided novel insights on PBMC secretome upregulation to promote disease progression and may lead to the identification of new therapeutic targets for novel regimens for CKD, ESRD and their accelerated cardiovascular disease, other inflammations and cancers. (Total words: 279).
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Affiliation(s)
- Ruijing Zhang
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA; Department of Nephrology, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, 030013, China; Department of Nephrology, The Affiliated People's Hospital of Shanxi Medical University, Taiyuan, Shanxi, 030012, China
| | - Jason Saredy
- Centers for Metabolic Disease Research, Cardiovascular Research, & Thrombosis Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Ying Shao
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Tian Yao
- Shanxi Medical University, Taiyuan, Shanxi Province, 030001, China
| | - Lu Liu
- Centers for Metabolic Disease Research, Cardiovascular Research, & Thrombosis Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Fatma Saaoud
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | | | - Yu Sun
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Candice Johnson
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Charles Drummer
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Hangfei Fu
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Yifan Lu
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Keman Xu
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Ming Liu
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA; Shanxi Medical University, Taiyuan, Shanxi Province, 030001, China
| | - Jirong Wang
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Elizabeth Cutler
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA; School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA
| | - Daohai Yu
- Department of Clinical Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Xiaohua Jiang
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Yafeng Li
- Department of Nephrology, The Affiliated People's Hospital of Shanxi Medical University, Taiyuan, Shanxi, 030012, China
| | - Rongshan Li
- Department of Nephrology, The Affiliated People's Hospital of Shanxi Medical University, Taiyuan, Shanxi, 030012, China
| | - Lihua Wang
- Department of Nephrology, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi, 030013, China
| | - Eric T Choi
- Division of Vascular and Endovascular Surgery, Department of Surgery, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA; Centers for Metabolic Disease Research, Cardiovascular Research, & Thrombosis Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA; Departments of Pharmacology, Microbiology and Immunology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Hong Wang
- Centers for Metabolic Disease Research, Cardiovascular Research, & Thrombosis Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA; Departments of Pharmacology, Microbiology and Immunology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Xiaofeng Yang
- Center for Inflammation, Translational & Clinical Lung Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA; Centers for Metabolic Disease Research, Cardiovascular Research, & Thrombosis Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA; Departments of Pharmacology, Microbiology and Immunology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA.
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6
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Couasnay G, Bon N, Devignes CS, Sourice S, Bianchi A, Véziers J, Weiss P, Elefteriou F, Provot S, Guicheux J, Beck-Cormier S, Beck L. PiT1/Slc20a1 Is Required for Endoplasmic Reticulum Homeostasis, Chondrocyte Survival, and Skeletal Development. J Bone Miner Res 2019; 34:387-398. [PMID: 30347511 DOI: 10.1002/jbmr.3609] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 09/26/2018] [Accepted: 10/22/2018] [Indexed: 01/09/2023]
Abstract
During skeletal mineralization, the sodium-phosphate co-transporter PiT1Slc20a1 is assumed to meet the phosphate requirements of bone-forming cells, although evidence is missing. Here, we used a conditional gene deletion approach to determine the role of PiT1 in growth plate chondrocytes. We show that PiT1 ablation shortly after birth generates a rapid and massive cell death in the center of the growth plate, together with an uncompensated endoplasmic reticulum (ER) stress, characterized by morphological changes and increased Chop, Atf4, and Bip expression. PiT1 expression in chondrocytes was not found at the cell membrane but co-localized with the ER marker ERp46, and was upregulated by the unfolded protein response cascade. In addition, we identified the protein disulfide isomerase (Pdi) ER chaperone as a PiT1 binding partner and showed that PiT1 ablation impaired Pdi reductase activity. The ER stress induced by PiT1 deficiency in chondrocytes was associated with intracellular retention of aggrecan and vascular endothelial growth factor A (Vegf-A), which was rescued by overexpressing a phosphate transport-deficient mutant of PiT1. Our data thus reveal a novel, Pi-transport independent function of PiT1, as a critical modulator of ER homeostasis and chondrocyte survival during endochondral ossification. © 2018 American Society for Bone and Mineral Research.
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Affiliation(s)
- Greig Couasnay
- INSERM, Unité mixte de Recherche (UMR) 1229, Regenerative Medicine and Skeleton (RMeS), Nantes-Atlantic National College of Veterinary Medicine, Food Science and Engineering, ONIRIS, Université de Nantes, Nantes, France.,Faculty of Dental Surgery of Nantes (UFR Odontologie), Université de Nantes, Nantes, France.,Department of Molecular and Human Genetics and Orthopedic Surgery, Baylor College of Medicine, Houston, TX, USA
| | - Nina Bon
- INSERM, Unité mixte de Recherche (UMR) 1229, Regenerative Medicine and Skeleton (RMeS), Nantes-Atlantic National College of Veterinary Medicine, Food Science and Engineering, ONIRIS, Université de Nantes, Nantes, France.,Faculty of Dental Surgery of Nantes (UFR Odontologie), Université de Nantes, Nantes, France
| | - Claire-Sophie Devignes
- INSERM, UMR 1132, Centre Viggo Petersen-Hôpital Lariboisière, Paris, France.,Université Paris Diderot, Sorbonne Paris-Cité, Paris, France
| | - Sophie Sourice
- INSERM, Unité mixte de Recherche (UMR) 1229, Regenerative Medicine and Skeleton (RMeS), Nantes-Atlantic National College of Veterinary Medicine, Food Science and Engineering, ONIRIS, Université de Nantes, Nantes, France.,Faculty of Dental Surgery of Nantes (UFR Odontologie), Université de Nantes, Nantes, France
| | - Arnaud Bianchi
- National Center for Scientific Research (CNRS), UMR 7365, IMoPA, Vandœuvre-lès-Nancy, France.,Faculté de Médecine, Université de Lorraine, Vandœuvre-lès-Nancy, France
| | - Joëlle Véziers
- INSERM, Unité mixte de Recherche (UMR) 1229, Regenerative Medicine and Skeleton (RMeS), Nantes-Atlantic National College of Veterinary Medicine, Food Science and Engineering, ONIRIS, Université de Nantes, Nantes, France.,Faculty of Dental Surgery of Nantes (UFR Odontologie), Université de Nantes, Nantes, France.,PHU 4 Odontologie, Neurochirurgie, Neurotraumatologie (OTONN), CHU de Nantes University Hospital Center, Nantes, France
| | - Pierre Weiss
- INSERM, Unité mixte de Recherche (UMR) 1229, Regenerative Medicine and Skeleton (RMeS), Nantes-Atlantic National College of Veterinary Medicine, Food Science and Engineering, ONIRIS, Université de Nantes, Nantes, France.,Faculty of Dental Surgery of Nantes (UFR Odontologie), Université de Nantes, Nantes, France.,PHU 4 Odontologie, Neurochirurgie, Neurotraumatologie (OTONN), CHU de Nantes University Hospital Center, Nantes, France
| | - Florent Elefteriou
- Department of Molecular and Human Genetics and Orthopedic Surgery, Baylor College of Medicine, Houston, TX, USA
| | - Sylvain Provot
- INSERM, UMR 1132, Centre Viggo Petersen-Hôpital Lariboisière, Paris, France.,Université Paris Diderot, Sorbonne Paris-Cité, Paris, France
| | - Jérôme Guicheux
- INSERM, Unité mixte de Recherche (UMR) 1229, Regenerative Medicine and Skeleton (RMeS), Nantes-Atlantic National College of Veterinary Medicine, Food Science and Engineering, ONIRIS, Université de Nantes, Nantes, France.,Faculty of Dental Surgery of Nantes (UFR Odontologie), Université de Nantes, Nantes, France.,PHU 4 Odontologie, Neurochirurgie, Neurotraumatologie (OTONN), CHU de Nantes University Hospital Center, Nantes, France
| | - Sarah Beck-Cormier
- INSERM, Unité mixte de Recherche (UMR) 1229, Regenerative Medicine and Skeleton (RMeS), Nantes-Atlantic National College of Veterinary Medicine, Food Science and Engineering, ONIRIS, Université de Nantes, Nantes, France.,Faculty of Dental Surgery of Nantes (UFR Odontologie), Université de Nantes, Nantes, France
| | - Laurent Beck
- INSERM, Unité mixte de Recherche (UMR) 1229, Regenerative Medicine and Skeleton (RMeS), Nantes-Atlantic National College of Veterinary Medicine, Food Science and Engineering, ONIRIS, Université de Nantes, Nantes, France.,Faculty of Dental Surgery of Nantes (UFR Odontologie), Université de Nantes, Nantes, France
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Michigami T, Kawai M, Yamazaki M, Ozono K. Phosphate as a Signaling Molecule and Its Sensing Mechanism. Physiol Rev 2018; 98:2317-2348. [DOI: 10.1152/physrev.00022.2017] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In mammals, phosphate balance is maintained by influx and efflux via the intestines, kidneys, bone, and soft tissue, which involves multiple sodium/phosphate (Na+/Pi) cotransporters, as well as regulation by several hormones. Alterations in the levels of extracellular phosphate exert effects on both skeletal and extra-skeletal tissues, and accumulating evidence has suggested that phosphate itself evokes signal transduction to regulate gene expression and cell behavior. Several in vitro studies have demonstrated that an elevation in extracellular Piactivates fibroblast growth factor receptor, Raf/MEK (mitogen-activated protein kinase/ERK kinase)/ERK (extracellular signal-regulated kinase) pathway and Akt pathway, which might involve the type III Na+/Picotransporter PiT-1. Excessive phosphate loading can lead to various harmful effects by accelerating ectopic calcification, enhancing oxidative stress, and dysregulating signal transduction. The responsiveness of mammalian cells to altered extracellular phosphate levels suggests that they may sense and adapt to phosphate availability, although the precise mechanism for phosphate sensing in mammals remains unclear. Unicellular organisms, such as bacteria and yeast, use some types of Pitransporters and other molecules, such as kinases, to sense the environmental Piavailability. Multicellular animals may need to integrate signals from various organs to sense the phosphate levels as a whole organism, similarly to higher plants. Clarification of the phosphate-sensing mechanism in humans may lead to the development of new therapeutic strategies to prevent and treat diseases caused by phosphate imbalance.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Masanobu Kawai
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Miwa Yamazaki
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Keiichi Ozono
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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8
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Bon N, Frangi G, Sourice S, Guicheux J, Beck-Cormier S, Beck L. Phosphate-dependent FGF23 secretion is modulated by PiT2/Slc20a2. Mol Metab 2018; 11:197-204. [PMID: 29551636 PMCID: PMC6001877 DOI: 10.1016/j.molmet.2018.02.007] [Citation(s) in RCA: 40] [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: 12/23/2017] [Revised: 02/12/2018] [Accepted: 02/15/2018] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE The canonical role of the bone-derived fibroblast growth factor 23 (Fgf23) is to regulate the serum inorganic phosphate (Pi) level. As part of a feedback loop, serum Pi levels control Fgf23 secretion through undefined mechanisms. We recently showed in vitro that the two high-affinity Na+-Pi co-transporters PiT1/Slc20a1 and PiT2/Slc20a2 were required for mediating Pi-dependent signaling. Here, we addressed the contribution of PiT1 and PiT2 to the regulation of Fgf23 secretion. METHODS To this aim, we used PiT2 KO and DMP1Cre; PiT1lox/lox fed Pi-modified diets, as well as ex vivo isolated long bone shafts. Fgf23 secretion and expression of Pi homeostasis-related genes were assessed. RESULTS In vivo, PiT2 KO mice responded inappropriately to low-Pi diets, displaying abnormally normal serum levels of intact Fgf23. Despite the high iFgf23 level, serum Pi levels remained unaffected, an effect that may relate to lower αKlotho expression in the kidney. Moreover, consistent with a role of PiT2 as a possible endocrine Pi sensor, the iFGF23/cFGF23 ratios were suppressed in PiT2 KO mice, irrespective of the Pi loads. While deletion of PiT1 in osteocytes using the DMP1-Cre mice was inefficient, adenovirus-mediated deletion of PiT1 in isolated long bone shafts suggested that PiT1 does not contribute to Pi-dependent regulation of Fgf23 secretion. In contrast, using isolated bone shafts from PiT2 KO mice, we showed that PiT2 was necessary for the appropriate Pi-dependent secretion of Fgf23, independently from possible endocrine regulatory loops. CONCLUSIONS Our data provide initial mechanistic insights underlying the Pi-dependent regulation of Fgf23 secretion in identifying PiT2 as a potential player in this process, at least in high Pi conditions. Targeting PiT2, therefore, could improve excess FGF23 in hyperphosphatemic conditions such as chronic kidney disease.
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Affiliation(s)
- Nina Bon
- Inserm, UMR 1229, RMeS, Regenerative Medicine and Skeleton, Université de Nantes, ONIRIS, Nantes, F-44042, France; Université de Nantes, UFR Odontologie, Nantes, F-44042, France
| | - Giulia Frangi
- Inserm, UMR 1229, RMeS, Regenerative Medicine and Skeleton, Université de Nantes, ONIRIS, Nantes, F-44042, France; Université de Nantes, UFR Odontologie, Nantes, F-44042, France
| | - Sophie Sourice
- Inserm, UMR 1229, RMeS, Regenerative Medicine and Skeleton, Université de Nantes, ONIRIS, Nantes, F-44042, France; Université de Nantes, UFR Odontologie, Nantes, F-44042, France
| | - Jérôme Guicheux
- Inserm, UMR 1229, RMeS, Regenerative Medicine and Skeleton, Université de Nantes, ONIRIS, Nantes, F-44042, France; Université de Nantes, UFR Odontologie, Nantes, F-44042, France; CHU Nantes, PHU 4 OTONN, Nantes, F-44042, France
| | - Sarah Beck-Cormier
- Inserm, UMR 1229, RMeS, Regenerative Medicine and Skeleton, Université de Nantes, ONIRIS, Nantes, F-44042, France; Université de Nantes, UFR Odontologie, Nantes, F-44042, France
| | - Laurent Beck
- Inserm, UMR 1229, RMeS, Regenerative Medicine and Skeleton, Université de Nantes, ONIRIS, Nantes, F-44042, France; Université de Nantes, UFR Odontologie, Nantes, F-44042, France.
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