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Friedman P, Mamonova T. The molecular sociology of NHERF1 PDZ proteins controlling renal hormone-regulated phosphate transport. Biosci Rep 2024; 44:BSR20231380. [PMID: 38465463 PMCID: PMC10987488 DOI: 10.1042/bsr20231380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 03/07/2024] [Accepted: 03/08/2024] [Indexed: 03/12/2024] Open
Abstract
Parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF23) control extracellular phosphate levels by regulating renal NPT2A-mediated phosphate transport by a process requiring the PDZ scaffold protein NHERF1. NHERF1 possesses two PDZ domains, PDZ1 and PDZ2, with identical core-binding GYGF motifs explicitly recognizing distinct binding partners that play different and specific roles in hormone-regulated phosphate transport. The interaction of PDZ1 and the carboxy-terminal PDZ-binding motif of NPT2A (C-TRL) is required for basal phosphate transport. PDZ2 is a regulatory domain that scaffolds multiple biological targets, including kinases and phosphatases involved in FGF23 and PTH signaling. FGF23 and PTH trigger disassembly of the NHERF1-NPT2A complex through reversible hormone-stimulated phosphorylation with ensuing NPT2A sequestration, down-regulation, and cessation of phosphate absorption. In the absence of NHERF1-NPT2A interaction, inhibition of FGF23 or PTH signaling results in disordered phosphate homeostasis and phosphate wasting. Additional studies are crucial to elucidate how NHERF1 spatiotemporally coordinates cellular partners to regulate extracellular phosphate levels.
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Affiliation(s)
- Peter A. Friedman
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, U.S.A
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, U.S.A
| | - Tatyana Mamonova
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, U.S.A
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Sasaki S, Shiozaki Y, Hanazaki A, Koike M, Tanifuji K, Uga M, Kawahara K, Kaneko I, Kawamoto Y, Wiriyasermkul P, Hasegawa T, Amizuka N, Miyamoto KI, Nagamori S, Kanai Y, Segawa H. Tmem174, a regulator of phosphate transporter prevents hyperphosphatemia. Sci Rep 2022; 12:6353. [PMID: 35428804 PMCID: PMC9012787 DOI: 10.1038/s41598-022-10409-3] [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: 12/01/2021] [Accepted: 04/05/2022] [Indexed: 11/23/2022] Open
Abstract
Renal type II sodium-dependent inorganic phosphate (Pi) transporters NaPi2a and NaPi2c cooperate with other organs to strictly regulate the plasma Pi concentration. A high Pi load induces expression and secretion of the phosphaturic hormones parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) that enhance urinary Pi excretion and prevent the onset of hyperphosphatemia. How FGF23 secretion from bone is increased by a high Pi load and the setpoint of the plasma Pi concentration, however, are unclear. Here, we investigated the role of Transmembrane protein 174 (Tmem174) and observed evidence for gene co-expression networks in NaPi2a and NaPi2c function. Tmem174 is localized in the renal proximal tubules and interacts with NaPi2a, but not NaPi2c. In Tmem174-knockout (KO) mice, the serum FGF23 concentration was markedly increased but increased Pi excretion and hypophosphatemia were not observed. In addition, Tmem174-KO mice exhibit reduced NaPi2a responsiveness to FGF23 and PTH administration. Furthermore, a dietary Pi load causes marked hyperphosphatemia and abnormal NaPi2a regulation in Tmem174-KO mice. Thus, Tmem174 is thought to be associated with FGF23 induction in bones and the regulation of NaPi2a to prevent an increase in the plasma Pi concentration due to a high Pi load and kidney injury.
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Affiliation(s)
- Sumire Sasaki
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Yuji Shiozaki
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Ai Hanazaki
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Megumi Koike
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Kazuya Tanifuji
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Minori Uga
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Kota Kawahara
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Ichiro Kaneko
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Yasuharu Kawamoto
- Department of Bio-System Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Pattama Wiriyasermkul
- Department of Laboratory Medicine, The Jikei University School of Medicine, Tokyo, Japan
| | - Tomoka Hasegawa
- Developmental Biology of Hard Tissue, Faculty of Dental Medicine, Hokkaido University, Sapporo, Japan
| | - Norio Amizuka
- Developmental Biology of Hard Tissue, Faculty of Dental Medicine, Hokkaido University, Sapporo, Japan
| | - Ken-Ichi Miyamoto
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan.,Graduate School of Agriculture, Ryukoku University, Ohtsu, Japan
| | - Shushi Nagamori
- Department of Laboratory Medicine, The Jikei University School of Medicine, Tokyo, Japan.
| | - Yoshikatsu Kanai
- Department of Bio-System Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan.
| | - Hiroko Segawa
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan.
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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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Abstract
Over the past 25 years, successive cloning of SLC34A1, SLC34A2 and SLC34A3, which encode the sodium-dependent inorganic phosphate (Pi) cotransport proteins 2a-2c, has facilitated the identification of molecular mechanisms that underlie the regulation of renal and intestinal Pi transport. Pi and various hormones, including parathyroid hormone and phosphatonins, such as fibroblast growth factor 23, regulate the activity of these Pi transporters through transcriptional, translational and post-translational mechanisms involving interactions with PDZ domain-containing proteins, lipid microdomains and acute trafficking of the transporters via endocytosis and exocytosis. In humans and rodents, mutations in any of the three transporters lead to dysregulation of epithelial Pi transport with effects on serum Pi levels and can cause cardiovascular and musculoskeletal damage, illustrating the importance of these transporters in the maintenance of local and systemic Pi homeostasis. Functional and structural studies have provided insights into the mechanism by which these proteins transport Pi, whereas in vivo and ex vivo cell culture studies have identified several small molecules that can modify their transport function. These small molecules represent potential new drugs to help maintain Pi homeostasis in patients with chronic kidney disease - a condition that is associated with hyperphosphataemia and severe cardiovascular and skeletal consequences.
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Håglin LM, Törnkvist B, Bäckman LO. High serum phosphate and triglyceride levels in smoking women and men with CVD risk and type 2 diabetes. Diabetol Metab Syndr 2014; 6:39. [PMID: 24636522 PMCID: PMC3995531 DOI: 10.1186/1758-5996-6-39] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 03/07/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Both low and high serum phosphate levels may be associated with morbidity and mortality from cardiovascular disease. As smoking increases risk for type 2 diabetes (as shown by dyslipidemia and hyperglycemia), we wanted to study whether smoking and type 2 diabetes were associated with serum phosphate and triglyceride levels independently from other CVD risk factors. METHODS Upon admittance to the Vindeln Health Education Centre (VHE-centre) for a four-week comprehensive lifestyle intervention, the participants (1408 women and 1096 men) completed a questionnaire that included their smoking habits - current smoker or non-smoker. We used multiple linear regression analyses to investigate the association between smoking and other CVD risk factors with S-P and S-TG levels. RESULTS In the non-type 2 diabetes populations, the smokers, compared to the non-smokers, had higher S-P and higher serum triglycerides (S-TG). In women, serum-TG in smokers with type 2 diabetes was higher than in smokers with non-type 2 diabetes. Non-type 2 diabetes patients exhibited an inverse relation between S-Glucose (S-Glu) and S-P and a positive association with S-TG. For men only, an association was seen between age (-) and S-Crea (-) and S-P. For women only, an association was seen between BMI (-) and S-Cholesterol (+) (S-Chol) and S-P. CONCLUSIONS Compared to non-smokers, smoking women with non-type 2 diabetes and smoking men with type 2 diabetes had a higher level of S-P and S-TG. The association between smoking and S-P and S-TG levels still existed after adjusting for age and CVD risk factors in the multiple linear regression analyses. TRIAL REGISTRATION The study has been registered as a sub-study to the Lifestyle Intervention Trial no. ISRCTN79355192.
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Affiliation(s)
- Lena M Håglin
- Department of Public Health and Clinical Medicine, Family Medicine, Umeå University, UMEÅ SE-901 87, Sweden
| | | | - Lennart O Bäckman
- Department of Public Health and Clinical Medicine, Family Medicine, Umeå University, UMEÅ SE-901 87, Sweden
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Wang B, Yang Y, Liu L, Blair HC, Friedman PA. NHERF1 regulation of PTH-dependent bimodal Pi transport in osteoblasts. Bone 2013; 52:268-77. [PMID: 23046970 PMCID: PMC3513631 DOI: 10.1016/j.bone.2012.10.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 09/18/2012] [Accepted: 10/01/2012] [Indexed: 02/01/2023]
Abstract
Control of systemic inorganic phosphate (Pi) levels is crucial for osteoid mineralization. Parathyroid hormone (PTH) mediates actions on phosphate homeostasis mostly by regulating the activity of the type 2 sodium-phosphate cotransporter (Npt2), and this action requires the PDZ protein NHERF1. Osteoblasts express Npt2 and in response to PTH enhance osteogenesis by increasing mineralized matrix. The regulation of Pi transport in osteoblasts is poorly understood. To address this gap we characterized PTH-dependent Pi transport and the role of NHERF1 in primary mouse calvarial osteoblasts. Under proliferating conditions osteoblasts express Npt2a, Npt2b, PTH receptor, and NHERF1. Npt2a mRNA expression was lower in calvarial osteoblasts from NHERF1-null mice. Under basal conditions Pi uptake in osteoblasts from wild-type mice was greater than that of knockout mice. PTH inhibited Pi uptake in proliferating osteoblasts from wild-type mice, but not in cells from knockout mice. In vitro induction of mineralization enhanced osteoblast differentiation and increased osterix and osteocalcin expression. Contrary to the results with proliferating osteoblasts, PTH increased Pi uptake and ATP secretion in differentiated osteoblasts from wild-type mice. PTH had no effect on Pi uptake or ATP release in differentiated osteoblasts from knockout mice. NHERF1 regulation of PTH-sensitive Pi uptake in proliferating osteoblasts is mediated by cAMP/PKA and PLC/PKC, while modulation of Pi uptake in differentiated osteoblasts depends only on cAMP/PKA signaling. The results suggest that NHERF1 cooperates with PTH in differentiated osteoblasts to increase matrix mineralization. We conclude that NHERF1 regulates PTH that differentially affects Na-dependent Pi transport at distinct stages of osteoblast proliferation and maturation.
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Affiliation(s)
- Bin Wang
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology & Chemical Biology, Pittsburgh, PA, USA
| | - Yanmei Yang
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology & Chemical Biology, Pittsburgh, PA, USA
| | - Li Liu
- Pittsburgh Veterans Affairs Medical Center and Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Harry C. Blair
- Pittsburgh Veterans Affairs Medical Center and Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Peter A. Friedman
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology & Chemical Biology, Pittsburgh, PA, USA
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Soundararajan R, Ziera T, Koo E, Ling K, Wang J, Borden SA, Pearce D. Scaffold protein connector enhancer of kinase suppressor of Ras isoform 3 (CNK3) coordinates assembly of a multiprotein epithelial sodium channel (ENaC)-regulatory complex. J Biol Chem 2012; 287:33014-25. [PMID: 22851176 DOI: 10.1074/jbc.m112.389148] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hormone regulation of ion transport in the kidney tubules is essential for fluid and electrolyte homeostasis in vertebrates. A large body of evidence has suggested that transporters and channels exist in multiprotein regulatory complexes; however, relatively little is known about the composition of these complexes or their assembly. The epithelial sodium channel (ENaC) in particular is tightly regulated by the salt-regulatory hormone aldosterone, which acts at least in part by increasing expression of the serine-threonine kinase SGK1. Here we show that aldosterone induces the formation of a 1.0-1.2-MDa plasma membrane complex, which includes ENaC, SGK1, and the ENaC inhibitor Nedd4-2, a key target of SGK1. We further show that this complex contains the PDZ domain-containing protein connector enhancer of kinase suppressor of Ras isoform 3 (CNK3). CNK3 physically interacts with ENaC, Nedd4-2, and SGK1; enhances the interactions among them; and stimulates ENaC function in a PDZ domain-dependent, aldosterone-induced manner. These results strongly suggest that CNK3 is a molecular scaffold, which coordinates the assembly of a multiprotein ENaC-regulatory complex and hence plays a central role in Na(+) homeostasis.
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Affiliation(s)
- Rama Soundararajan
- Division of Nephrology, Department of Medicine, University of California, San Francisco, California 94143, USA
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