1
|
Wan L, Huo J, Huang Q, Ji X, Song L, Zhang Z, Pan L, Fu J, Abd Elhamid MA, Soaud SA, Heakel RMY, Gao J, Wei S, El-Sappah AH. Genetics and metabolic responses of Artemisia annua L to the lake of phosphorus under the sparingly soluble phosphorus fertilizer: evidence from transcriptomics analysis. Funct Integr Genomics 2024; 24:26. [PMID: 38329581 DOI: 10.1007/s10142-024-01301-6] [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: 08/02/2023] [Revised: 01/14/2024] [Accepted: 01/16/2024] [Indexed: 02/09/2024]
Abstract
The medicinal herb Artemisia annua L. is prized for its capacity to generate artemisinin, which is used to cure malaria. Potentially influencing the biomass and secondary metabolite synthesis of A. annua is plant nutrition, particularly phosphorus (P). However, most soil P exist as insoluble inorganic and organic phosphates, which results to low P availability limiting plant growth and development. Although plants have developed several adaptation strategies to low P levels, genetics and metabolic responses to P status remain largely unknown. In a controlled greenhouse experiment, the sparingly soluble P form, hydroxyapatite (Ca5OH(PO4)3/CaP) was used to simulate calcareous soils with low P availability. In contrast, the soluble P form KH2PO4/KP was used as a control. A. annua's morphological traits, growth, and artemisinin concentration were determined, and RNA sequencing was used to identify the differentially expressed genes (DEGs) under two different P forms. Total biomass, plant height, leaf number, and stem diameter, as well as leaf area, decreased by 64.83%, 27.49%, 30.47%, 38.70%, and 54.64% in CaP compared to KP; however, LC-MS tests showed an outstanding 37.97% rise in artemisinin content per unit biomass in CaP contrary to KP. Transcriptome analysis showed 2015 DEGs (1084 up-regulated and 931 down-regulated) between two P forms, including 39 transcription factor (TF) families. Further analysis showed that DEGs were mainly enriched in carbohydrate metabolism, secondary metabolites biosynthesis, enzyme catalytic activity, signal transduction, and so on, such as tricarboxylic acid (TCA) cycle, glycolysis, starch and sucrose metabolism, flavonoid biosynthesis, P metabolism, and plant hormone signal transduction. Meanwhile, several artemisinin biosynthesis genes were up-regulated, including DXS, GPPS, GGPS, MVD, and ALDH, potentially increasing artemisinin accumulation. Furthermore, 21 TF families, including WRKY, MYB, bHLH, and ERF, were up-regulated in reaction to CaP, confirming their importance in P absorption, internal P cycling, and artemisinin biosynthesis regulation. Our results will enable us to comprehend how low P availability impacts the parallel transcriptional control of plant development, growth, and artemisinin production in A. annua. This study could lay the groundwork for future research into the molecular mechanisms underlying A. annua's low P adaptation.
Collapse
Affiliation(s)
- Lingyun Wan
- Guangxi Key Laboratory of High-Quality Formation and Utilization of Dao-di Herbs, Guangxi Botanical Garden of Medicinal Plants, Nanning, China
| | - Juan Huo
- Guangxi Key Laboratory of High-Quality Formation and Utilization of Dao-di Herbs, Guangxi Botanical Garden of Medicinal Plants, Nanning, China
| | - Qiulan Huang
- Faculty of Agriculture, Forestry and Food Engineering, Yibin University, Yibin, China
| | - Xiaowen Ji
- Guangxi Key Laboratory of High-Quality Formation and Utilization of Dao-di Herbs, Guangxi Botanical Garden of Medicinal Plants, Nanning, China
| | - Lisha Song
- Guangxi Key Laboratory of High-Quality Formation and Utilization of Dao-di Herbs, Guangxi Botanical Garden of Medicinal Plants, Nanning, China
| | - Zhanjiang Zhang
- Guangxi Key Laboratory of High-Quality Formation and Utilization of Dao-di Herbs, Guangxi Botanical Garden of Medicinal Plants, Nanning, China
| | - Limei Pan
- Guangxi Key Laboratory of High-Quality Formation and Utilization of Dao-di Herbs, Guangxi Botanical Garden of Medicinal Plants, Nanning, China
| | - Jine Fu
- Guangxi Key Laboratory of High-Quality Formation and Utilization of Dao-di Herbs, Guangxi Botanical Garden of Medicinal Plants, Nanning, China
| | | | - Salma A Soaud
- Genetics Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
| | - Rania M Y Heakel
- Genetics Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt
| | - Jihai Gao
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Shugen Wei
- Guangxi Key Laboratory of High-Quality Formation and Utilization of Dao-di Herbs, Guangxi Botanical Garden of Medicinal Plants, Nanning, China.
| | - Ahmed H El-Sappah
- Faculty of Agriculture, Forestry and Food Engineering, Yibin University, Yibin, China.
- Genetics Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt.
| |
Collapse
|
2
|
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.
Collapse
Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.
| |
Collapse
|
3
|
Jennings ML. Role of transporters in regulating mammalian intracellular inorganic phosphate. Front Pharmacol 2023; 14:1163442. [PMID: 37063296 PMCID: PMC10097972 DOI: 10.3389/fphar.2023.1163442] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 03/17/2023] [Indexed: 03/31/2023] Open
Abstract
This review summarizes the current understanding of the role of plasma membrane transporters in regulating intracellular inorganic phosphate ([Pi]In) in mammals. Pi influx is mediated by SLC34 and SLC20 Na+-Pi cotransporters. In non-epithelial cells other than erythrocytes, Pi influx via SLC20 transporters PiT1 and/or PiT2 is balanced by efflux through XPR1 (xenotropic and polytropic retrovirus receptor 1). Two new pathways for mammalian Pi transport regulation have been described recently: 1) in the presence of adequate Pi, cells continuously internalize and degrade PiT1. Pi starvation causes recycling of PiT1 from early endosomes to the plasma membrane and thereby increases the capacity for Pi influx; and 2) binding of inositol pyrophosphate InsP8 to the SPX domain of XPR1 increases Pi efflux. InsP8 is degraded by a phosphatase that is strongly inhibited by Pi. Therefore, an increase in [Pi]In decreases InsP8 degradation, increases InsP8 binding to SPX, and increases Pi efflux, completing a feedback loop for [Pi]In homeostasis. Published data on [Pi]In by magnetic resonance spectroscopy indicate that the steady state [Pi]In of skeletal muscle, heart, and brain is normally in the range of 1–5 mM, but it is not yet known whether PiT1 recycling or XPR1 activation by InsP8 contributes to Pi homeostasis in these organs. Data on [Pi]In in cultured cells are variable and suggest that some cells can regulate [Pi] better than others, following a change in [Pi]Ex. More measurements of [Pi]In, influx, and efflux are needed to determine how closely, and how rapidly, mammalian [Pi]In is regulated during either hyper- or hypophosphatemia.
Collapse
|
4
|
Sun H, Xu X, Luo J, Ma T, Cui J, Liu M, Xiong B, Zhu S, Liu JY. Mechanisms of PiT2-loop7 Missense Mutations Induced Pi Dyshomeostasis. Neurosci Bull 2023; 39:57-68. [PMID: 35713844 PMCID: PMC9849530 DOI: 10.1007/s12264-022-00893-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 04/14/2022] [Indexed: 01/25/2023] Open
Abstract
PiT2 is an inorganic phosphate (Pi) transporter whose mutations are linked to primary familial brain calcification (PFBC). PiT2 mainly consists of two ProDom (PD) domains and a large intracellular loop region (loop7). The PD domains are crucial for the Pi transport, but the role of PiT2-loop7 remains unclear. In PFBC patients, mutations in PiT2-loop7 are mainly nonsense or frameshift mutations that probably cause PFBC due to C-PD1131 deletion. To date, six missense mutations have been identified in PiT2-loop7; however, the mechanisms by which these mutations cause PFBC are poorly understood. Here, we found that the p.T390A and p.S434W mutations in PiT2-loop7 decreased the Pi transport activity and cell surface levels of PiT2. Furthermore, we showed that these two mutations attenuated its membrane localization by affecting adenosine monophosphate-activated protein kinase (AMPK)- or protein kinase B (AKT)-mediated PiT2 phosphorylation. In contrast, the p.S121C and p.S601W mutations in the PD domains did not affect PiT2 phosphorylation but rather impaired its substrate-binding abilities. These results suggested that missense mutations in PiT2-loop7 can cause Pi dyshomeostasis by affecting the phosphorylation-regulated cell-surface localization of PiT2. This study helps understand the pathogenesis of PFBC caused by PiT2-loop7 missense mutations and indicates that increasing the phosphorylation levels of PiT2-loop7 could be a promising strategy for developing PFBC therapies.
Collapse
Affiliation(s)
- Hao Sun
- College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Xuan Xu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Junyu Luo
- College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Tingbin Ma
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Jiaming Cui
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Mugen Liu
- College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Bo Xiong
- Department of Forensic Medicine, Tongji Medical College, HUST, Wuhan, 430030, China
| | - Shujia Zhu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China.
| | - Jing-Yu Liu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China.
| |
Collapse
|
5
|
The Pathology of Primary Familial Brain Calcification: Implications for Treatment. Neurosci Bull 2022; 39:659-674. [PMID: 36469195 PMCID: PMC10073384 DOI: 10.1007/s12264-022-00980-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 07/10/2022] [Indexed: 12/08/2022] Open
Abstract
AbstractPrimary familial brain calcification (PFBC) is an inherited neurodegenerative disorder mainly characterized by progressive calcium deposition bilaterally in the brain, accompanied by various symptoms, such as dystonia, ataxia, parkinsonism, dementia, depression, headaches, and epilepsy. Currently, the etiology of PFBC is largely unknown, and no specific prevention or treatment is available. During the past 10 years, six causative genes (SLC20A2, PDGFRB, PDGFB, XPR1, MYORG, and JAM2) have been identified in PFBC. In this review, considering mechanistic studies of these genes at the cellular level and in animals, we summarize the pathogenesis and potential preventive and therapeutic strategies for PFBC patients. Our systematic analysis suggests a classification for PFBC genetic etiology based on several characteristics, provides a summary of the known composition of brain calcification, and identifies some potential therapeutic targets for PFBC.
Collapse
|
6
|
The Interplay between Uremic Toxins and Albumin, Membrane Transporters and Drug Interaction. Toxins (Basel) 2022; 14:toxins14030177. [PMID: 35324674 PMCID: PMC8949274 DOI: 10.3390/toxins14030177] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/21/2022] [Accepted: 02/24/2022] [Indexed: 01/10/2023] Open
Abstract
Uremic toxins are a heterogeneous group of molecules that accumulate in the body due to the progression of chronic kidney disease (CKD). These toxins are associated with kidney dysfunction and the development of comorbidities in patients with CKD, being only partially eliminated by dialysis therapies. Importantly, drugs used in clinical treatments may affect the levels of uremic toxins, their tissue disposition, and even their elimination through the interaction of both with proteins such as albumin and cell membrane transporters. In this context, protein-bound uremic toxins (PBUTs) are highlighted for their high affinity for albumin, the most abundant serum protein with multiple binding sites and an ability to interact with drugs. Membrane transporters mediate the cellular influx and efflux of various uremic toxins, which may also compete with drugs as substrates, and both may alter transporter activity or expression. Therefore, this review explores the interaction mechanisms between uremic toxins and albumin, as well as membrane transporters, considering their potential relationship with drugs used in clinical practice.
Collapse
|
7
|
Thomas NE, Feng W, Henzler-Wildman KA. A solid-supported membrane electrophysiology assay for efficient characterization of ion-coupled transport. J Biol Chem 2021; 297:101220. [PMID: 34562455 PMCID: PMC8517846 DOI: 10.1016/j.jbc.2021.101220] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 09/14/2021] [Accepted: 09/20/2021] [Indexed: 12/03/2022] Open
Abstract
Transport stoichiometry determination can provide great insight into the mechanism and function of ion-coupled transporters. Traditional reversal potential assays are a reliable, general method for determining the transport stoichiometry of ion-coupled transporters, but the time and material costs of this technique hinder investigations of transporter behavior under multiple experimental conditions. Solid-supported membrane electrophysiology (SSME) allows multiple recordings of liposomal or membrane samples adsorbed onto a sensor and is sensitive enough to detect transport currents from moderate-flux transporters that are inaccessible to traditional electrophysiology techniques. Here, we use SSME to develop a new method for measuring transport stoichiometry with greatly improved throughput. Using this technique, we were able to verify the recent report of a fixed 2:1 stoichiometry for the proton:guanidinium antiporter Gdx, reproduce the 1H+:2Cl- antiport stoichiometry of CLC-ec1, and confirm loose proton:nitrate coupling for CLC-ec1. Furthermore, we were able to demonstrate quantitative exchange of internal contents of liposomes adsorbed onto SSME sensors to allow multiple experimental conditions to be tested on a single sample. Our SSME method provides a fast, easy, general method for measuring transport stoichiometry, which will facilitate future mechanistic and functional studies of ion-coupled transporters.
Collapse
Affiliation(s)
- Nathan E Thomas
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Wei Feng
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, USA
| | | |
Collapse
|
8
|
Pizzagalli MD, Bensimon A, Superti‐Furga G. A guide to plasma membrane solute carrier proteins. FEBS J 2021; 288:2784-2835. [PMID: 32810346 PMCID: PMC8246967 DOI: 10.1111/febs.15531] [Citation(s) in RCA: 155] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/07/2020] [Accepted: 08/17/2020] [Indexed: 12/13/2022]
Abstract
This review aims to serve as an introduction to the solute carrier proteins (SLC) superfamily of transporter proteins and their roles in human cells. The SLC superfamily currently includes 458 transport proteins in 65 families that carry a wide variety of substances across cellular membranes. While members of this superfamily are found throughout cellular organelles, this review focuses on transporters expressed at the plasma membrane. At the cell surface, SLC proteins may be viewed as gatekeepers of the cellular milieu, dynamically responding to different metabolic states. With altered metabolism being one of the hallmarks of cancer, we also briefly review the roles that surface SLC proteins play in the development and progression of cancer through their influence on regulating metabolism and environmental conditions.
Collapse
Affiliation(s)
- Mattia D. Pizzagalli
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
| | - Ariel Bensimon
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
| | - Giulio Superti‐Furga
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
- Center for Physiology and PharmacologyMedical University of ViennaAustria
| |
Collapse
|
9
|
Ichida Y, Ohtomo S, Yamamoto T, Murao N, Tsuboi Y, Kawabe Y, Segawa H, Horiba N, Miyamoto KI, Floege J. Evidence of an intestinal phosphate transporter alternative to type IIb sodium-dependent phosphate transporter in rats with chronic kidney disease. Nephrol Dial Transplant 2021; 36:68-75. [PMID: 32879980 PMCID: PMC7771979 DOI: 10.1093/ndt/gfaa156] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Indexed: 12/14/2022] Open
Abstract
Background Phosphate is absorbed in the small intestine via passive flow and active transport.NaPi-IIb, a type II sodium-dependent phosphate transporter, is considered to mediate active phosphate transport in rodents. To study the regulation of intestinal phosphate transport in chronic kidney disease (CKD), we analyzed the expression levels of NaPi-IIb, pituitary-specific transcription factor 1 (PiT-1) and PiT-2 and the kinetics of intestinal phosphate transport using two CKD models. Methods CKD was induced in rats via adenine orThy1 antibody injection. Phosphate uptake by intestinal brush border membrane vesicles (BBMV) and the messenger RNA (mRNA) expression of NaPi-IIb, PiT-1 and PiT-2 were analyzed. The protein expression level of NaPi-IIb was measured by mass spectrometry (e.g. liquid chromatography tandem mass spectrometry). Results In normal rats, phosphate uptake into BBMV consisted of a single saturable component and its Michaelis constant (Km) was comparable to that of NaPi-IIb. The maximum velocity (Vmax) correlated with mRNA and protein levels of NaPi-IIb. In the CKD models, intestinal phosphate uptake consisted of two saturable components. The Vmax of the higher-affinity transport, which is thought to be responsible for NaPi-IIb, significantly decreased and the decrease correlated with reduced NaPi-IIb expression. The Km of the lower-affinity transport was comparable to that of PiT-1 and -2. PiT-1 mRNA expression was much higher than that of PiT-2, suggesting that PiT-1 was mostly responsible for phosphate transport. Conclusions This study suggests that the contribution of NaPi-IIb to intestinal phosphate absorption dramatically decreases in rats with CKD and that a low-affinity alternative to NaPi-IIb, in particular PiT-1, is upregulated in a compensatory manner in CKD.
Collapse
Affiliation(s)
- Yasuhiro Ichida
- Research Division, Chugai Pharmaceutical Co., Ltd, Shizuoka, Japan
| | - Shuichi Ohtomo
- Research Division, Chugai Pharmaceutical Co., Ltd, Shizuoka, Japan
| | - Tessai Yamamoto
- Translational Research Division, Chugai Pharmaceutical Co., Ltd, Shizuoka, Japan
| | - Naoaki Murao
- Translational Research Division, Chugai Pharmaceutical Co., Ltd, Shizuoka, Japan
| | - Yoshinori Tsuboi
- Research Division, Chugai Pharmaceutical Co., Ltd, Shizuoka, Japan
| | - Yoshiki Kawabe
- Research Division, Chugai Pharmaceutical Co., Ltd, Shizuoka, Japan
| | - Hiroko Segawa
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Naoshi Horiba
- Research Division, Chugai Pharmaceutical Co., Ltd, Shizuoka, Japan
| | - Ken-Ichi Miyamoto
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Jürgen Floege
- Division of Nephrology and Clinical Immunology, RWTH Aachen University Hospital, Aachen, Germany
| |
Collapse
|
10
|
Behrens JL, Schnepel N, Hansen K, Hustedt K, Burmester M, Klinger S, Breves G, Muscher-Banse AS. Modulation of Intestinal Phosphate Transport in Young Goats Fed a Low Phosphorus Diet. Int J Mol Sci 2021; 22:ijms22020866. [PMID: 33467106 PMCID: PMC7831023 DOI: 10.3390/ijms22020866] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 01/07/2021] [Accepted: 01/13/2021] [Indexed: 12/03/2022] Open
Abstract
The intestinal absorption of phosphate (Pi) takes place transcellularly through the active NaPi-cotransporters type IIb (NaPiIIb) and III (PiT1 and PiT2) and paracellularly by diffusion through tight junction (TJ) proteins. The localisation along the intestines and the regulation of Pi absorption differ between species and are not fully understood. It is known that 1,25-dihydroxy-vitamin D3 (1,25-(OH)2D3) and phosphorus (P) depletion modulate intestinal Pi absorption in vertebrates in different ways. In addition to the apical uptake into the enterocytes, there are uncertainties regarding the basolateral excretion of Pi. Functional ex vivo experiments in Ussing chambers and molecular studies of small intestinal epithelia were carried out on P-deficient goats in order to elucidate the transepithelial Pi route in the intestine as well as the underlying mechanisms of its regulation and the proteins, which may be involved. The dietary P reduction had no effect on the duodenal and ileal Pi transport rate in growing goats. The ileal PiT1 and PiT2 mRNA expressions increased significantly, while the ileal PiT1 protein expression, the mid jejunal claudin-2 mRNA expression and the serum 1,25-(OH)2D3 levels were significantly reduced. These results advance the state of knowledge concerning the complex mechanisms of the Pi homeostasis in vertebrates.
Collapse
|
11
|
Pastor‐Arroyo EM, Knöpfel T, Imenez Silva PH, Schnitzbauer U, Poncet N, Biber J, Wagner CA, Hernando N. Intestinal epithelial ablation of Pit-2/Slc20a2 in mice leads to sustained elevation of vitamin D 3 upon dietary restriction of phosphate. Acta Physiol (Oxf) 2020; 230:e13526. [PMID: 32564464 DOI: 10.1111/apha.13526] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/27/2020] [Accepted: 06/15/2020] [Indexed: 12/31/2022]
Abstract
AIM Several Na+ -dependent phosphate cotransporters, namely NaPi-IIb/SLC34A2, Pit-1/SLC20A1 and Pit-2/SLC20A2, are expressed at the apical membrane of enterocytes but their contribution to active absorption of phosphate is unclear. The aim of this study was to compare their pattern of mRNA expression along the small and large intestine and to analyse the effect of intestinal depletion of Pit-2 on phosphate homeostasis. METHODS Intestinal epithelial Pit-2-deficient mice were generated by crossing floxed Pit-2 with villin-Cre mice. Mice were fed 2 weeks standard or low phosphate diets. Stool, urine, plasma and intestinal and renal tissue were collected. Concentration of electrolytes and hormones, expression of mRNAs and proteins and intestinal transport of tracers were analysed. RESULTS Intestinal mRNA expression of NaPi-IIb and Pit-1 is segment-specific, whereas the abundance of Pit-2 mRNA is more homogeneous. In ileum, NaPi-IIb mRNA expression is restricted to enterocytes, whereas Pit-2 mRNA is found in epithelial and non-epithelial cells. Overall, their mRNA expression is not regulated by dietary phosphate. The absence of Pit-2 from intestinal epithelial cells does not affect systemic phosphate homeostasis under normal dietary conditions. However, in response to dietary phosphate restriction, Pit-2-deficient mice showed exacerbated hypercalciuria and sustained elevation of 1,25(OH)2 vitamin D3 . CONCLUSIONS In mice, the intestinal Na+ /phosphate cotransporters are not coexpressed in all segments. NaPi-IIb but not Pit-2 mRNA is restricted to epithelial cells. Intestinal epithelial Pit-2 does not contribute significantly to absorption of phosphate under normal dietary conditions. However, it may play a more significant role upon dietary phosphate restriction.
Collapse
Affiliation(s)
| | - Thomas Knöpfel
- Institute of Physiology University of Zürich Zürich Switzerland
| | | | | | - Nadège Poncet
- Institute of Physiology University of Zürich Zürich Switzerland
| | - Jürg Biber
- Institute of Physiology University of Zürich Zürich Switzerland
| | | | - Nati Hernando
- Institute of Physiology University of Zürich Zürich Switzerland
| |
Collapse
|
12
|
Serna J, Bergwitz C. Importance of Dietary Phosphorus for Bone Metabolism and Healthy Aging. Nutrients 2020; 12:E3001. [PMID: 33007883 PMCID: PMC7599912 DOI: 10.3390/nu12103001] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/25/2020] [Accepted: 09/26/2020] [Indexed: 12/13/2022] Open
Abstract
Inorganic phosphate (Pi) plays a critical function in many tissues of the body: for example, as part of the hydroxyapatite in the skeleton and as a substrate for ATP synthesis. Pi is the main source of dietary phosphorus. Reduced bioavailability of Pi or excessive losses in the urine causes rickets and osteomalacia. While critical for health in normal amounts, dietary phosphorus is plentiful in the Western diet and is often added to foods as a preservative. This abundance of phosphorus may reduce longevity due to metabolic changes and tissue calcifications. In this review, we examine how dietary phosphorus is absorbed in the gut, current knowledge about Pi sensing, and endocrine regulation of Pi levels. Moreover, we also examine the roles of Pi in different tissues, the consequences of low and high dietary phosphorus in these tissues, and the implications for healthy aging.
Collapse
Affiliation(s)
- Juan Serna
- Yale College, Yale University, New Haven, CT 06511, USA;
| | - Clemens Bergwitz
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06519, USA
| |
Collapse
|
13
|
Thomas L, Xue J, Tomilin VN, Pochynyuk OM, Dominguez Rieg JA, Rieg T. PF-06869206 is a selective inhibitor of renal P i transport: evidence from in vitro and in vivo studies. Am J Physiol Renal Physiol 2020; 319:F541-F551. [PMID: 32744087 DOI: 10.1152/ajprenal.00146.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Plasma phosphate (Pi) levels are tightly controlled, and elevated plasma Pi levels are associated with an increased risk of cardiovascular complications and death. Two renal transport proteins mediate the majority of Pi reabsorption: Na+-phosphate cotransporters Npt2a and Npt2c, with Npt2a accounting for 70-80% of Pi reabsorption. The aim of the present study was to determine the in vitro effects of a novel Npt2a inhibitor (PF-06869206) in opossum kidney (OK) cells as well as determine its selectivity in vivo in Npt2a knockout (Npt2a-/-) mice. In OK cells, Npt2a inhibitor caused dose-dependent reductions of Na+-dependent Pi uptake (IC50: ~1.4 μmol/L), whereas the unselective Npt2 inhibitor phosphonoformic acid (PFA) resulted in an ~20% stronger inhibition of Pi uptake. The dose-dependent inhibitory effects were present after 24 h of incubation with both low- and high-Pi media. Michaelis-Menten kinetics in OK cells identified an ~2.4-fold higher Km for Pi in response to Npt2a inhibition with no significant change in apparent Vmax. Higher parathyroid hormone concentrations decreased Pi uptake equivalent to the maximal inhibitory effect of Npt2a inhibitor. In vivo, the Npt2a inhibitor induced a dose-dependent increase in urinary Pi excretion in wild-type mice (ED50: ~23 mg/kg), which was completely absent in Npt2a-/- mice, alongside a lack of decrease in plasma Pi. Of note, the Npt2a inhibitor-induced dose-dependent increase in urinary Na+ excretion was still present in Npt2a-/- mice, a response possibly mediated by an off-target acute inhibitory effect of the Npt2a inhibitor on open probability of the epithelial Na+ channel in the cortical collecting duct.
Collapse
Affiliation(s)
- Linto Thomas
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
| | - Jianxiang Xue
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
| | - Viktor N Tomilin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas
| | - Oleh M Pochynyuk
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas
| | - Jessica A Dominguez Rieg
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
| | - Timo Rieg
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
| |
Collapse
|
14
|
Tsai JY, Chu CH, Lin MG, Chou YH, Hong RY, Yen CY, Hsiao CD, Sun YJ. Structure of the sodium-dependent phosphate transporter reveals insights into human solute carrier SLC20. SCIENCE ADVANCES 2020; 6:eabb4024. [PMID: 32821837 PMCID: PMC7413737 DOI: 10.1126/sciadv.abb4024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 06/26/2020] [Indexed: 05/14/2023]
Abstract
Inorganic phosphate (Pi) is a fundamental and essential element for nucleotide biosynthesis, energy supply, and cellular signaling in living organisms. Human phosphate transporter (hPiT) dysfunction causes numerous diseases, but the molecular mechanism underlying transporters remains elusive. We report the structure of the sodium-dependent phosphate transporter from Thermotoga maritima (TmPiT) in complex with sodium and phosphate (TmPiT-Na/Pi) at 2.3-angstrom resolution. We reveal that one phosphate and two sodium ions (Pi-2Na) are located at the core of TmPiT and that the third sodium ion (Nafore) is located near the inner membrane boundary. We propose an elevator-like mechanism for sodium and phosphate transport by TmPiT, with the TmPiT-Na/Pi complex adopting an inward occluded conformation. We found that disease-related hPiT variants carry mutations in the corresponding sodium- and phosphate-binding residues identified in TmPiT. Our three-dimensional structure of TmPiT provides a framework for understanding PiT dysfunction and for future structure-based drug design.
Collapse
Affiliation(s)
- Jia-Yin Tsai
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsinchu 30013, Taiwan (R.O.C.)
| | - Chen-Hsi Chu
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsinchu 30013, Taiwan (R.O.C.)
| | - Min-Guan Lin
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan (R.O.C.)
| | - Ying-Hsuan Chou
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsinchu 30013, Taiwan (R.O.C.)
| | - Ruei-Yi Hong
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsinchu 30013, Taiwan (R.O.C.)
| | - Cheng-Yi Yen
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsinchu 30013, Taiwan (R.O.C.)
| | - Chwan-Deng Hsiao
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan (R.O.C.)
- Corresponding author. (C.-D.H.); (Y.-J.S.)
| | - Yuh-Ju Sun
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsinchu 30013, Taiwan (R.O.C.)
- Corresponding author. (C.-D.H.); (Y.-J.S.)
| |
Collapse
|
15
|
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.
Collapse
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
| |
Collapse
|
16
|
Gushgari-Doyle S, Alvarez-Cohen L. Effects of Arsenic on Trichloroethene-Dechlorination Activities of Dehalococcoides mccartyi 195. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:1276-1285. [PMID: 31913608 PMCID: PMC7792829 DOI: 10.1021/acs.est.9b06527] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Arsenic and trichloroethene (TCE) are among the most prevalent groundwater contaminants in the United States. Co-contamination of these two compounds has been detected at 63% of current TCE-contaminated National Priorities List sites. When in situ TCE reductive dechlorination is stimulated by the addition of fermentable substrates to generate a reducing environment, the presence of arsenic can be problematic because of the potential for increased mobilization and toxicity caused by the reduction of arsenate [As(V)] to arsenite [As(III)]. This study assesses the effects of arsenic exposure on the TCE-dechlorinating activities of Dehalococcoides mccartyi strain 195. Our results indicate that 9.1 μM As(III) caused a 50% decrease in D. mccartyi cell growth. While As(V) concentrations up to 200 μM did not initially impact TCE dechlorination, inhibition was observed in cultures amended with 200 μM As(V) and 100 μM As(V) in 12 and 17 days, respectively, corresponding with the accumulation of As(III). Transcriptomic and metabolomic analyses were performed to evaluate cellular responses to both As(V) and As(III) stress. Amendment of amino acids enhanced arsenic tolerance of D. mccartyi. Results from this study improve our understanding of potential inhibitions of D. mccartyi metabolism caused by arsenic and can inform the design of bioremediation strategies at co-contaminated sites.
Collapse
Affiliation(s)
- Sara Gushgari-Doyle
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710
| | - Lisa Alvarez-Cohen
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710
- Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA
| |
Collapse
|
17
|
Hortells L, Guillén N, Sosa C, Sorribas V. Several phosphate transport processes are present in vascular smooth muscle cells. Am J Physiol Heart Circ Physiol 2019; 318:H448-H460. [PMID: 31886722 DOI: 10.1152/ajpheart.00433.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We have studied inorganic phosphate (Pi) handling in rat aortic vascular smooth muscle cells (VSMC) using 32P-radiotracer assays. Our results have revealed a complex set of mechanisms consisting of 1) well-known PiT1/PiT2-mediated sodium-dependent Pi transport; 2) Slc20-unrelated sodium-dependent Pi transport that is sensitive to the stilbene derivatives 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) and 4-acetamido-4-isothiocyanostilbene-2,2-disulfonate (SITS); 3) a sodium-independent Pi uptake system that is competitively inhibited by sulfate, bicarbonate, and arsenate and is weakly inhibited by DIDS, SITS, and phosphonoformate; and 4) an exit pathway from the cell that is partially chloride dependent and unrelated to the known anion-exchangers expressed in VSMC. The inhibitions of sodium-independent Pi transport by sulfate and of sodium-dependent transport by SITS were studied in greater detail. The maximal inhibition by sulfate was similar to that of Pi itself, with a very high inhibition constant (212 mM). SITS only partially inhibited sodium-dependent Pi transport, but the Ki was very low (14 µM). Nevertheless, SITS and DIDS did not inhibit Pi transport in Xenopus laevis oocytes expressing PiT1 or PiT2. Both the sodium-dependent and sodium-independent transport systems were highly dependent on VSMC confluence and on the differentiation state, but they were not modified by incubating VSMC for 7 days with 2 mM Pi under nonprecipitating conditions. This work not only shows that the Pi handling by cells is highly complex but also that the transport systems are shared with other ions such as bicarbonate or sulfate.NEW & NOTEWORTHY In addition to the inorganic phosphate (Pi) transporters PiT1 and PiT2, rat vascular smooth muscle cells show a sodium-dependent Pi transport system that is inhibited by DIDS and SITS. A sodium-independent Pi uptake system of high affinity is also expressed, which is inhibited by sulfate, bicarbonate, and arsenate. The exit of excess Pi is through an exchange with extracellular chloride. Whereas the metabolic effects of the inhibitors, if any, cannot be discarded, kinetic analysis during initial velocity suggests competitive inhibition.
Collapse
Affiliation(s)
- Luis Hortells
- Veterinary Faculty, Department of Toxicology, University of Zaragoza, Zaragoza, Spain
| | - Natalia Guillén
- Veterinary Faculty, Department of Toxicology, University of Zaragoza, Zaragoza, Spain
| | - Cecilia Sosa
- Veterinary Faculty, Department of Toxicology, University of Zaragoza, Zaragoza, Spain
| | - Víctor Sorribas
- Veterinary Faculty, Department of Toxicology, University of Zaragoza, Zaragoza, Spain
| |
Collapse
|
18
|
Shet D, Ghosh J, Ajith S, Awachat VB, Bhat KS, Gowda NKS, Pal D, Elangovan AV. Dietary phytase supplementation during peak egg laying cycle of White Leghorn hens on nutrient utilization and functional gene mRNA expression in duodenum and kidney. BIOL RHYTHM RES 2019. [DOI: 10.1080/09291016.2018.1499220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Divya Shet
- ICAR- National Institute of Animal Nutrition and Physiology, Bangalore, India
- Department of Biotechnology, Jain University, Bangalore, India
| | - Jyotirmoy Ghosh
- ICAR- National Institute of Animal Nutrition and Physiology, Bangalore, India
| | - Sreeja Ajith
- ICAR- National Institute of Animal Nutrition and Physiology, Bangalore, India
- Department of Microbiology, Jain University, Bangalore, India
| | | | | | | | - Dintaran Pal
- ICAR- National Institute of Animal Nutrition and Physiology, Bangalore, India
| | | |
Collapse
|
19
|
Li J, Dong W, Li Z, Wang H, Gao H, Zhang Y. Impact of SLC20A1 on the Wnt/β‑catenin signaling pathway in somatotroph adenomas. Mol Med Rep 2019; 20:3276-3284. [PMID: 31432167 PMCID: PMC6755178 DOI: 10.3892/mmr.2019.10555] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 07/12/2019] [Indexed: 12/26/2022] Open
Abstract
Studies have revealed that genetic and functional aberrations of oncogenes, tumor‑suppressor genes, signaling pathways and receptors are among the most prominent events in pituitary tumorigenesis, and a potent biomarker would be helpful for early diagnosis, subsequent treatment and disease control. The present study investigated the expression signatures of solute carrier family 20 member 1, also known as phosphate transporter 1 (SLC20A1) and the Wnt/β‑catenin signaling pathway in 52 patients with somatotroph adenomas. According to immunohistochemistry analysis, the H‑score of SLC20A1 was 222.6±15.2 in invasive tumor samples and 144.5±30.4 in non‑invasive tumor samples (P<0.01), while the H‑scores of β‑catenin were 210.1±21.4 and 134.9±32.7, respectively (P<0.05). The H‑scores of Wnt inhibitory factor 1 (Wif1) exhibited the opposite trend, with scores of 134.5±22.7 and 253.6±14.8, respectively (P<0.01). The H‑scores of SLC20A1 were negatively associated with those of Wif1 in somatotroph adenomas (correlation coefficient r=‑0.367). The mean progression‑free survival in the low SLC20A1 group was longer than that in the group with high SLC20A1 H‑scores (P=0.024). Reverse transcription‑quantitative PCR (RT‑qPCR) and western blotting confirmed the interference efficiency of the segments short hairpin (Sh)‑B‑SLC20A1 and Sh‑C‑SLC20A1. Cell proliferation experiments revealed that the cell viability of the Sh‑B‑SLC20A1 group was 76.3±4.5, 65.7±3.7 and 53.1±3.2% of that of control GH3 cells after 24, 48 and 72 h of transfection, respectively, while the cell viability of the Sh‑C‑SLC20A1 group was 86.4±5.7, 75.6±4.4 and 67.5±3.8%, respectively (P<0.05). ELISA analysis demonstrated the growth hormone (GH) levels in the Sh‑B‑SLC20A1 and Sh‑C‑SLC20A1 groups to be 34.7±10.4 and 54.6±14.4%, respectively, of that of control GH3 cells (P<0.05). The transmembrane invasion assay revealed that knocking down SLC20A1 significantly suppressed cell invasion in the Sh‑B‑SLC20A1 and Sh‑C‑SLC20A1 groups. RT‑qPCR and western blotting demonstrated that Sh‑B‑SLC20A1 and Sh‑C‑SLC20A1 evidently increased the levels of Wif1 and secreted frizzled‑related protein 4. The present data suggested that SLC20A1 levels are positively associated with tumor size, invasive behavior and tumor recurrence in somatotroph adenomas. Furthermore, SLC20A1 may be associated with the activation of the Wnt/β‑catenin signaling pathway.
Collapse
Affiliation(s)
- Jianhua Li
- Key Laboratory of Central Nervous System Injury Research, Beijing Neurosurgical Institute, Capital Medical University, Beijing 100070, P.R. China
| | - Wei Dong
- Department of Neurosurgery, Tangshan People's Hospital, Tangshan, Hebei 063001, P.R. China
| | - Zhenye Li
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, P.R. China
| | - Hongyun Wang
- Key Laboratory of Central Nervous System Injury Research, Beijing Neurosurgical Institute, Capital Medical University, Beijing 100070, P.R. China
| | - Hua Gao
- Key Laboratory of Central Nervous System Injury Research, Beijing Neurosurgical Institute, Capital Medical University, Beijing 100070, P.R. China
| | - Yazhuo Zhang
- Key Laboratory of Central Nervous System Injury Research, Beijing Neurosurgical Institute, Capital Medical University, Beijing 100070, P.R. China
| |
Collapse
|
20
|
Abstract
Calcium kidney stones are common worldwide. Most are idiopathic and composed of calcium oxalate. Calcium phosphate is present in around 80% and may initiate stone formation. Stone production is multifactorial with a polygenic genetic contribution. Phosphaturia is found frequently among stone formers but until recently received scant attention. This review examines possible mechanisms for the phosphaturia and its relevance to stone formation from a wide angle. There is a striking lack of clinical data. Phosphaturia is associated, but not correlated, with hypercalciuria, increased 1,25 dihydroxy-vitamin D [1,25 (OH)2D], and sometimes evidence of disturbances in proximal renal tubular function. Phosphate reabsorption in the proximal renal tubules requires tightly regulated interaction of many proteins. Paracellular flow through intercellular tight junctions is the major route of phosphate absorption from the intestine and can be reduced therapeutically in hyperphosphatemic patients. In monogenic defects stones develop when phosphaturia is associated with hypercalciuria, generally explained by increased 1,25 (OH)2D production in response to hypophosphatemia. Calcification does not occur in disorders with increased FGF23 when phosphaturia occurs in isolation and 1,25 (OH)2D is suppressed. Candidate gene studies have identified mutations in the phosphate transporters, but in few individuals. One genome-wide study identified a polymorphism of the phosphate transporter gene SLC34A4 associated with stones. Others did not find mutations obviously linked to phosphate reabsorption. Future genetic studies should have a wide trawl and should focus initially on groups of patients with clearly defined phenotypes. The global data should be pooled.
Collapse
Affiliation(s)
- Valerie Walker
- Department of Clinical Biochemistry, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom.
| |
Collapse
|
21
|
Jacquillet G, Unwin RJ. Physiological regulation of phosphate by vitamin D, parathyroid hormone (PTH) and phosphate (Pi). Pflugers Arch 2019; 471:83-98. [PMID: 30393837 PMCID: PMC6326012 DOI: 10.1007/s00424-018-2231-z] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/20/2018] [Accepted: 10/25/2018] [Indexed: 01/05/2023]
Abstract
Inorganic phosphate (Pi) is an abundant element in the body and is essential for a wide variety of key biological processes. It plays an essential role in cellular energy metabolism and cell signalling, e.g. adenosine and guanosine triphosphates (ATP, GTP), and in the composition of phospholipid membranes and bone, and is an integral part of DNA and RNA. It is an important buffer in blood and urine and contributes to normal acid-base balance. Given its widespread role in almost every molecular and cellular function, changes in serum Pi levels and balance can have important and untoward effects. Pi homoeostasis is maintained by a counterbalance between dietary Pi absorption by the gut, mobilisation from bone and renal excretion. Approximately 85% of total body Pi is present in bone and only 1% is present as free Pi in extracellular fluids. In humans, extracellular concentrations of inorganic Pi vary between 0.8 and 1.2 mM, and in plasma or serum Pi exists in both its monovalent and divalent forms (H2PO4- and HPO42-). In the intestine, approximately 30% of Pi absorption is vitamin D regulated and dependent. To help maintain Pi balance, reabsorption of filtered Pi along the renal proximal tubule (PT) is via the NaPi-IIa and NaPi-IIc Na+-coupled Pi cotransporters, with a smaller contribution from the PiT-2 transporters. Endocrine factors, including, vitamin D and parathyroid hormone (PTH), as well as newer factors such as fibroblast growth factor (FGF)-23 and its coreceptor α-klotho, are intimately involved in the control of Pi homeostasis. A tight regulation of Pi is critical, since hyperphosphataemia is associated with increased cardiovascular morbidity in chronic kidney disease (CKD) and hypophosphataemia with rickets and growth retardation. This short review considers the control of Pi balance by vitamin D, PTH and Pi itself, with an emphasis on the insights gained from human genetic disorders and genetically modified mouse models.
Collapse
Affiliation(s)
- Grégory Jacquillet
- Centre for Nephrology, University College London (UCL), Royal Free Campus, Rowland Hill Street, London, NW3 2PF, UK
| | - Robert J Unwin
- Centre for Nephrology, University College London (UCL), Royal Free Campus, Rowland Hill Street, London, NW3 2PF, UK.
- AstraZeneca IMED ECD CVRM R&D, Gothenburg, Sweden.
| |
Collapse
|
22
|
Sorribas V, Guillén N, Sosa C. Substrates and inhibitors of phosphate transporters: from experimental tools to pathophysiological relevance. Pflugers Arch 2018; 471:53-65. [DOI: 10.1007/s00424-018-2241-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 11/21/2018] [Accepted: 11/25/2018] [Indexed: 12/26/2022]
|
23
|
Potapenko E, Cordeiro CD, Huang G, Storey M, Wittwer C, Dutta AK, Jessen HJ, Starai VJ, Docampo R. 5-Diphosphoinositol pentakisphosphate (5-IP 7) regulates phosphate release from acidocalcisomes and yeast vacuoles. J Biol Chem 2018; 293:19101-19112. [PMID: 30315104 DOI: 10.1074/jbc.ra118.005884] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 10/10/2018] [Indexed: 12/21/2022] Open
Abstract
Acidocalcisomes of Trypanosoma brucei and the acidocalcisome-like vacuoles of Saccharomyces cerevisiae are acidic calcium compartments that store polyphosphate (polyP). Both organelles possess a phosphate-sodium symporter (TbPho91 and Pho91p in T. brucei and yeast, respectively), but the roles of these transporters in growth and orthophosphate (Pi) transport are unclear. We found here that Tbpho91 -/- trypanosomes have a lower growth rate under phosphate starvation and contain larger acidocalcisomes that have increased Pi content. Heterologous expression of TbPHO91 in Xenopus oocytes followed by two-electrode voltage clamp recordings disclosed that myo-inositol polyphosphates stimulate both sodium-dependent depolarization of the oocyte membrane potential and Pi conductance. Deletion of the SPX domain in TbPho91 abolished this stimulation. Inositol pyrophosphates such as 5-diphosphoinositol pentakisphosphate generated outward currents in Na+/Pi-loaded giant vacuoles prepared from WT or from TbPHO91-expressing pho91Δ strains but not from the pho91Δ yeast strains or from the pho91Δ strains expressing PHO91 or TbPHO91 with mutated SPX domains. Our results indicate that TbPho91 and Pho91p are responsible for vacuolar Pi and Na+ efflux and that myo-inositol polyphosphates stimulate the Na+/Pi symporter activities through their SPX domains.
Collapse
Affiliation(s)
- Evgeniy Potapenko
- From the Center for Tropical and Emerging Global Diseases and.,the Departments of Cellular Biology and
| | - Ciro D Cordeiro
- From the Center for Tropical and Emerging Global Diseases and.,the Departments of Cellular Biology and
| | - Guozhong Huang
- From the Center for Tropical and Emerging Global Diseases and
| | - Melissa Storey
- From the Center for Tropical and Emerging Global Diseases and
| | - Christopher Wittwer
- the Department of Chemistry and Pharmacy, University of Freiburg, 79098 Freiburg, Germany
| | - Amit K Dutta
- the Department of Chemistry and Pharmacy, University of Freiburg, 79098 Freiburg, Germany
| | - Henning J Jessen
- the Department of Chemistry and Pharmacy, University of Freiburg, 79098 Freiburg, Germany
| | - Vincent J Starai
- Microbiology and Infectious Diseases, University of Georgia, Athens, Georgia 30602 and
| | - Roberto Docampo
- From the Center for Tropical and Emerging Global Diseases and .,the Departments of Cellular Biology and
| |
Collapse
|
24
|
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.
Collapse
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
| |
Collapse
|
25
|
Forster IC. The molecular mechanism of SLC34 proteins: insights from two decades of transport assays and structure-function studies. Pflugers Arch 2018; 471:15-42. [PMID: 30244375 DOI: 10.1007/s00424-018-2207-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/06/2018] [Accepted: 09/11/2018] [Indexed: 01/08/2023]
Abstract
The expression cloning some 25 years ago of the first member of SLC34 solute carrier family, the renal sodium-coupled inorganic phosphate cotransporter (NaPi-IIa) from rat and human tissue, heralded a new era of research into renal phosphate handling by focussing on the carrier proteins that mediate phosphate transport. The cloning of NaPi-IIa was followed by that of the intestinal NaPi-IIb and renal NaPi-IIc isoforms. These three proteins constitute the main secondary-active Na+-driven pathways for apical entry of inorganic phosphate (Pi) across renal and intestinal epithelial, as well as other epithelial-like organs. The key role these proteins play in mammalian Pi homeostasis was revealed in the intervening decades by numerous in vitro and animal studies, including the development of knockout animals for each gene and the detection of naturally occurring mutations that can lead to Pi-handling dysfunction in humans. In addition to characterising their physiological regulation, research has also focused on understanding the underlying transport mechanism and identifying structure-function relationships. Over the past two decades, this research effort has used real-time electrophysiological and fluorometric assays together with novel computational biology strategies to develop a detailed, but still incomplete, understanding of the transport mechanism of SLC34 proteins at the molecular level. This review will focus on how our present understanding of their molecular mechanism has evolved in this period by highlighting the key experimental findings.
Collapse
Affiliation(s)
- Ian C Forster
- Ion Channels and Human Diseases Laboratory, Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia.
| |
Collapse
|
26
|
Hernando N, Wagner CA. Mechanisms and Regulation of Intestinal Phosphate Absorption. Compr Physiol 2018; 8:1065-1090. [PMID: 29978897 DOI: 10.1002/cphy.c170024] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
States of hypo- and hyperphosphatemia have deleterious consequences including rickets/osteomalacia and renal/cardiovascular disease, respectively. Therefore, the maintenance of appropriate plasma levels of phosphate is an essential requirement for health. This control is executed by the collaborative action of intestine and kidney whose capacities to (re)absorb phosphate are regulated by a number of hormonal and metabolic factors, among them parathyroid hormone, fibroblast growth factor 23, 1,25(OH)2 vitamin D3 , and dietary phosphate. The molecular mechanisms responsible for the transepithelial transport of phosphate across enterocytes are only partially understood. Indeed, whereas renal reabsorption entirely relies on well-characterized active transport mechanisms of phosphate across the renal proximal epithelia, intestinal absorption proceeds via active and passive mechanisms, with the molecular identity of the passive component still unknown. The active absorption of phosphate depends mostly on the activity and expression of the sodium-dependent phosphate cotransporter NaPi-IIb (SLC34A2), which is highly regulated by many of the factors, mentioned earlier. Physiologically, the contribution of NaPi-IIb to the maintenance of phosphate balance appears to be mostly relevant during periods of low phosphate availability. Therefore, its role in individuals living in industrialized societies with high phosphate intake is probably less relevant. Importantly, small increases in plasma phosphate, even within normal range, associate with higher risk of cardiovascular disease. Therefore, therapeutic approaches to treat hyperphosphatemia, including dietary phosphate restriction and phosphate binders, aim at reducing intestinal absorption. Here we review the current state of research in the field. © 2017 American Physiological Society. Compr Physiol 8:1065-1090, 2018.
Collapse
Affiliation(s)
- Nati Hernando
- National Center for Competence in Research NCCR Kidney.CH, Institute of Physiology, University Zurich-Irchel, Zurich, Switzerland
| | - Carsten A Wagner
- National Center for Competence in Research NCCR Kidney.CH, Institute of Physiology, University Zurich-Irchel, Zurich, Switzerland
| |
Collapse
|
27
|
Bon N, Couasnay G, Bourgine A, Sourice S, Beck-Cormier S, Guicheux J, Beck L. Phosphate (P i)-regulated heterodimerization of the high-affinity sodium-dependent P i transporters PiT1/Slc20a1 and PiT2/Slc20a2 underlies extracellular P i sensing independently of P i uptake. J Biol Chem 2017; 293:2102-2114. [PMID: 29233890 DOI: 10.1074/jbc.m117.807339] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 11/16/2017] [Indexed: 12/24/2022] Open
Abstract
Extracellular phosphate (Pi) can act as a signaling molecule that directly alters gene expression and cellular physiology. The ability of cells or organisms to detect changes in extracellular Pi levels implies the existence of a Pi-sensing mechanism that signals to the body or individual cell. However, unlike in prokaryotes, yeasts, and plants, the molecular players involved in Pi sensing in mammals remain unknown. In this study, we investigated the involvement of the high-affinity, sodium-dependent Pi transporters PiT1 and PiT2 in mediating Pi signaling in skeletal cells. We found that deletion of PiT1 or PiT2 blunted the Pi-dependent ERK1/2-mediated phosphorylation and subsequent gene up-regulation of the mineralization inhibitors matrix Gla protein and osteopontin. This result suggested that both PiTs are necessary for Pi signaling. Moreover, the ERK1/2 phosphorylation could be rescued by overexpressing Pi transport-deficient PiT mutants. Using cross-linking and bioluminescence resonance energy transfer approaches, we found that PiT1 and PiT2 form high-abundance homodimers and Pi-regulated low-abundance heterodimers. Interestingly, in the absence of sodium-dependent Pi transport activity, the PiT1-PiT2 heterodimerization was still regulated by extracellular Pi levels. Of note, when two putative Pi-binding residues, Ser-128 (in PiT1) and Ser-113 (in PiT2), were substituted with alanine, the PiT1-PiT2 heterodimerization was no longer regulated by extracellular Pi These observations suggested that Pi binding rather than Pi uptake may be the key factor in mediating Pi signaling through the PiT proteins. Taken together, these results demonstrate that Pi-regulated PiT1-PiT2 heterodimerization mediates Pi sensing independently of Pi uptake.
Collapse
Affiliation(s)
- Nina Bon
- From INSERM, U1229, RMeS "Regenerative Medicine and Skeleton," STEP team "Skeletal Physiopathology and Joint Regenerative Medicine," Nantes F-44042, France.,the Université de Nantes, UMR-S 1229, RMeS, UFR Odontologie, Nantes F-44042, France, and
| | - Greig Couasnay
- From INSERM, U1229, RMeS "Regenerative Medicine and Skeleton," STEP team "Skeletal Physiopathology and Joint Regenerative Medicine," Nantes F-44042, France.,the Université de Nantes, UMR-S 1229, RMeS, UFR Odontologie, Nantes F-44042, France, and
| | - Annabelle Bourgine
- From INSERM, U1229, RMeS "Regenerative Medicine and Skeleton," STEP team "Skeletal Physiopathology and Joint Regenerative Medicine," Nantes F-44042, France.,the Université de Nantes, UMR-S 1229, RMeS, UFR Odontologie, Nantes F-44042, France, and
| | - Sophie Sourice
- From INSERM, U1229, RMeS "Regenerative Medicine and Skeleton," STEP team "Skeletal Physiopathology and Joint Regenerative Medicine," Nantes F-44042, France.,the Université de Nantes, UMR-S 1229, RMeS, UFR Odontologie, Nantes F-44042, France, and
| | - Sarah Beck-Cormier
- From INSERM, U1229, RMeS "Regenerative Medicine and Skeleton," STEP team "Skeletal Physiopathology and Joint Regenerative Medicine," Nantes F-44042, France.,the Université de Nantes, UMR-S 1229, RMeS, UFR Odontologie, Nantes F-44042, France, and
| | - Jérôme Guicheux
- From INSERM, U1229, RMeS "Regenerative Medicine and Skeleton," STEP team "Skeletal Physiopathology and Joint Regenerative Medicine," Nantes F-44042, France.,the Université de Nantes, UMR-S 1229, RMeS, UFR Odontologie, Nantes F-44042, France, and.,CHU Nantes, PHU 4 OTONN, Nantes F-44042, France
| | - Laurent Beck
- From INSERM, U1229, RMeS "Regenerative Medicine and Skeleton," STEP team "Skeletal Physiopathology and Joint Regenerative Medicine," Nantes F-44042, France, .,the Université de Nantes, UMR-S 1229, RMeS, UFR Odontologie, Nantes F-44042, France, and
| |
Collapse
|
28
|
Candeal E, Caldas YA, Guillén N, Levi M, Sorribas V. Intestinal phosphate absorption is mediated by multiple transport systems in rats. Am J Physiol Gastrointest Liver Physiol 2017; 312:G355-G366. [PMID: 28232455 DOI: 10.1152/ajpgi.00244.2016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 01/30/2017] [Accepted: 02/04/2017] [Indexed: 01/31/2023]
Abstract
Apical inorganic phosphate (Pi) transport in the small intestine seems to be mainly mediated by the sodium/Pi cotransporter NaPi2b. To verify this role, we have studied the combined effects of pH, phosphonoformate, and Pi deprivation on intestinal Pi transport. Rats were fed, ad libitum, three fodders containing 1.2, 0.6, or 0.1% Pi for 1, 5, or 10 days. Pi deprivation (0.1%) increased both sodium-activated and sodium-independent Pi transport in brush-border membrane vesicles from the duodenum and jejunum for all three times. Alkaline pH inhibited Pi transport, despite the increasing concentration of [Formula: see text] (NaPi2b substrate), whereas acidity increased transport when the concentration of the PiT1/PiT2 substrate, [Formula: see text], was at its highest. The effect of Pi deprivation was maximal at acid pH, but both basal and upregulated transport were inhibited (70%) with phosphonoformate, an inhibitor of NaPi2b. PiT2 and NaPi2b protein abundance increased after 24 h of Pi deprivation in the duodenum, jejunum, and ileum, whereas PiT1 required 5-10 days in the duodenum and jejunum. Therefore, whereas transporter expressions are partially correlated with Pi transport adaptation, the pH effect precludes NaPi2b, and phosphonoformic acid precludes PiT1 and PiT2 as the main transporters. Transport and transporter expression were also inconsistent when feeding was limited to 4 h daily, because the 1.2% Pi diet paradoxically increased Pi transport in the duodenum and jejunum, but NaPi2b and PiT1 expressions only increased with the 0.1% diet. These findings suggest the presence of a major transporter that carries [Formula: see text] and is inhibited by phosphonoformate.NEW & NOTEWORTHY The combined effects of dietary inorganic phosphate (Pi) content, pH, and phosphonoformate inhibition suggest that the resulting apical Pi transport in the small intestine cannot be fully explained by the presence of NaPi2b, PiT1, or PiT2. We provide evidence of the presence of a new sodium-coupled Pi transporter that uses [Formula: see text] as the preferred substrate and is inhibited by phosphonoformate, and its expression correlates with Pi transport in all assayed conditions.
Collapse
Affiliation(s)
- Eduardo Candeal
- Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and
| | - Yupanqui A Caldas
- Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and.,Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Natalia Guillén
- Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and
| | - Moshe Levi
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Víctor Sorribas
- Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and
| |
Collapse
|
29
|
Zheng R, Wang J, Liu M, Duan G, Gao X, Bai S, Han Y. Molecular cloning and functional analysis of two phosphate transporter genes from Rhizopogon luteolus and Leucocortinarius bulbiger, two ectomycorrhizal fungi of Pinus tabulaeformis. MYCORRHIZA 2016; 26:633-44. [PMID: 27098350 DOI: 10.1007/s00572-016-0702-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Accepted: 04/14/2016] [Indexed: 05/23/2023]
Abstract
Inorganic phosphorus (Pi) is essential for plant growth, and phosphate (P) deficiency is a primary limiting factor in Pinus tabulaeformis development in northern China. P acquisition in mycorrhizal plants is highly dependent on the activities of phosphate transporters of their root-associated fungi. In the current study, two phosphate transporter genes, RlPT and LbPT, were isolated from Rhizopogon luteolus and Leucocortinarius bulbiger, respectively, two ectomycorrhizal fungi forming symbiotic interactions with the P. tabulaeformis. Phylogenetic analysis suggested that the sequence of the phosphate transporter of L. bulbiger is most closely related to a phosphate transporter of Hebeloma cylindrosporum, whereas the phosphate transporter of R. luteolus is most closely related to that of Piloderma croceum. The subcellular localization indicated that RlPT and LbPT were expressed in the plasma membrane. The complementation assay in yeast indicated that both RlPT and LbPT partially compensated for the absence of phosphate transporter activity in the MB192 yeast strain, with a K m value of 57.90 μmol/L Pi for RlPT and 35.87 μmol/L Pi for LbPT. qPCR analysis revealed that RlPT and LbPT were significantly up-regulated at lower P availability, which may enhance P uptake and transport under Pi starvation. Our results suggest that RlPT and LbPT presumably play a key role in Pi acquisition by P. tabulaeformis via ectomycorrhizal fungi.
Collapse
Affiliation(s)
- Rong Zheng
- College of Forestry, Inner Mongolia Agricultural University, Hohhot, 010019, Inner Mongolia, China
- College of Life Science and Technology, Inner Mongolia Normal University, Hohhot, 010020, Inner Mongolia, China
| | - Jugang Wang
- College of Forestry, Inner Mongolia Agricultural University, Hohhot, 010019, Inner Mongolia, China
- South Subtropical Crops Research Institute, Chinese Academy of Tropical Agricultural Science, Zhanjiang, 524091, Guangdong, China
| | - Min Liu
- College of Forestry, Inner Mongolia Agricultural University, Hohhot, 010019, Inner Mongolia, China
| | - Guozhen Duan
- College of Forestry, Inner Mongolia Agricultural University, Hohhot, 010019, Inner Mongolia, China
| | - Xiaomin Gao
- South Subtropical Crops Research Institute, Chinese Academy of Tropical Agricultural Science, Zhanjiang, 524091, Guangdong, China
| | - Shulan Bai
- College of Forestry, Inner Mongolia Agricultural University, Hohhot, 010019, Inner Mongolia, China.
| | - Yachao Han
- Fuyang Vocational and Technical College, Fuyang, 236031, Anhui, China
| |
Collapse
|
30
|
Zhang SF, Yuan CJ, Chen Y, Chen XH, Li DX, Liu JL, Lin L, Wang DZ. Comparative Transcriptomic Analysis Reveals Novel Insights into the Adaptive Response of Skeletonema costatum to Changing Ambient Phosphorus. Front Microbiol 2016; 7:1476. [PMID: 27703451 PMCID: PMC5028394 DOI: 10.3389/fmicb.2016.01476] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 09/05/2016] [Indexed: 12/11/2022] Open
Abstract
Phosphorus (P) is a limiting macronutrient for diatom growth and productivity in the ocean. Much effort has been devoted to the physiological response of marine diatoms to ambient P change, however, the whole-genome molecular mechanisms are poorly understood. Here, we utilized RNA-Seq to compare the global gene expression patterns of a marine diatom Skeletonema costatum grown in inorganic P-replete, P-deficient, and inorganic- and organic-P resupplied conditions. In total 34,942 unique genes were assembled and 20.8% of them altered significantly in abundance under different P conditions. Genes encoding key enzymes/proteins involved in P utilization, nucleotide metabolism, photosynthesis, glycolysis, and cell cycle regulation were significantly up-regulated in P-deficient cells. Genes participating in circadian rhythm regulation, such as circadian clock associated 1, were also up-regulated in P-deficient cells. The response of S. costatum to ambient P deficiency shows several similarities to the well-described responses of other marine diatom species, but also has its unique features. S. costatum has evolved the ability to re-program its circadian clock and intracellular biological processes in response to ambient P deficiency. This study provides new insights into the adaptive mechanisms to ambient P deficiency in marine diatoms.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Da-Zhi Wang
- State Key Laboratory of Marine Environmental Science, Department of Environmental Science and Engineering, College of the Environment and Ecology, Xiamen UniversityXiamen, China
| |
Collapse
|
31
|
Rozentryt P, Niedziela JT, Hudzik B, Lekston A, Doehner W, Jankowska EA, Nowak J, von Haehling S, Partyka R, Rywik T, Anker SD, Ponikowski P, Poloński L. Higher serum phosphorus is associated with catabolic/anabolic imbalance in heart failure. J Cachexia Sarcopenia Muscle 2015; 6:325-34. [PMID: 26672973 PMCID: PMC4670741 DOI: 10.1002/jcsm.12026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 11/06/2014] [Accepted: 02/20/2015] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND A higher serum phosphate level is associated with worse outcome. Energy-demanding intracellular transport of phosphate is needed to secure anion bioavailability. In heart failure (HF), energy starvation may modify intracellular and serum levels of phosphate. We analysed determinants of serum phosphates in HF and assessed if catabolic/anabolic balance (CAB) was associated with elevation of serum phosphate. METHODS We retrospectively reviewed data from 1029 stable patients with HF and have calculated negative (loss) and positive (gain) components of weight change from the onset of HF till index date. The algebraic sum of these components was taken as CAB. The univariate and multivariable predictors of serum phosphorus were calculated. In quintiles of CAB, we have estimated odds ratios for serum phosphorus above levels previously identified to increase risk of mortality. As a reference, we have selected a CAB quintile with similar loss and gain. RESULTS Apart from sex, age, and kidney function, we identified serum sodium, N-terminal fragment of pro-brain-type natriuretic peptide, and CAB as independent predictors of serum phosphorus. The odds for serum phosphorus above thresholds found in literature to increase risk were highest in more catabolic patients. In most catabolic quintile relative to neutral balance, the odds across selected phosphorus thresholds rose, gradually peaking at 1.30 mmol/L with a value of 3.29 (95% confidence interval: 2.00-5.40, P < 0.0001) in an unadjusted analysis and 2.55 (95% confidence interval: 1.38-2.72, P = 0.002) in a fully adjusted model. CONCLUSIONS Metabolic status is an independent determinant of serum phosphorus in HF. Higher catabolism is associated with serum phosphorus above mortality risk-increasing thresholds.
Collapse
Affiliation(s)
- Piotr Rozentryt
- Third Department of Cardiology, Silesian Centre for Heart Diseases, Medical University of Silesia Zabrze, Poland
| | - Jacek T Niedziela
- Third Department of Cardiology, Silesian Centre for Heart Diseases, Medical University of Silesia Zabrze, Poland
| | - Bartosz Hudzik
- Third Department of Cardiology, Silesian Centre for Heart Diseases, Medical University of Silesia Zabrze, Poland
| | - Andrzej Lekston
- Third Department of Cardiology, Silesian Centre for Heart Diseases, Medical University of Silesia Zabrze, Poland
| | - Wolfram Doehner
- Centre for Stroke Research Berlin, Charité Medical School Berlin, Germany
| | - Ewa A Jankowska
- Department of Heart Diseases, Wroclaw Medical University Wroclaw, Poland
| | - Jolanta Nowak
- Third Department of Cardiology, Silesian Centre for Heart Diseases, Medical University of Silesia Zabrze, Poland
| | - Stephan von Haehling
- Division of Innovative Clinical Trials, Department of Cardiology and Pneumology, University Medical Center Göttingen (UMG) Göttingen, Germany
| | - Robert Partyka
- Clinical Division of Anaesthesiology and Intensive Therapy of the Department of Anesthesiology, Intensive Treatment and Emergency Medicine, Medical University of Silesia Zabrze, Poland
| | - Tomasz Rywik
- Department of Heart Failure and Transplantology, Institute of Cardiology Warsaw, Poland
| | - Stefan D Anker
- Division of Innovative Clinical Trials, Department of Cardiology and Pneumology, University Medical Center Göttingen (UMG) Göttingen, Germany
| | - Piotr Ponikowski
- Department of Heart Diseases, Wroclaw Medical University Wroclaw, Poland
| | - Lech Poloński
- Third Department of Cardiology, Silesian Centre for Heart Diseases, Medical University of Silesia Zabrze, Poland
| |
Collapse
|
32
|
Jimenez V, Docampo R. TcPho91 is a contractile vacuole phosphate sodium symporter that regulates phosphate and polyphosphate metabolism in Trypanosoma cruzi. Mol Microbiol 2015; 97:911-25. [PMID: 26031800 DOI: 10.1111/mmi.13075] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2015] [Indexed: 02/03/2023]
Abstract
We have identified a phosphate transporter (TcPho91) localized to the bladder of the contractile vacuole complex (CVC) of Trypanosoma cruzi, the etiologic agent of Chagas disease. TcPho91 has 12 transmembrane domains, an N-terminal regulatory SPX (named after SYG1, Pho81 and XPR1) domain and an anion permease domain. Functional expression in Xenopus laevis oocytes followed by two-electrode voltage clamp showed that TcPho91 is a low-affinity transporter with a Km for Pi in the millimolar range, and sodium-dependency. Epimastigotes overexpressing TcPho91-green fluorescent protein have significantly higher levels of pyrophosphate (PPi ) and short-chain polyphosphate (polyP), suggesting accumulation of Pi in these cells. Moreover, when overexpressing parasites were maintained in a medium with low Pi , they grew at higher rates than control parasites. Only one allele of TcPho91 in the CL strain encodes for the complete open reading frame, while the other one is truncated encoding for only the N-terminal domain. Taking advantage of this characteristic, knockdown experiments were performed resulting in cells with reduced growth rate as well as a reduction in PPi and short-chain polyP levels. Our results indicate that TcPho91 is a phosphate sodium symporter involved in Pi homeostasis in T. cruzi.
Collapse
Affiliation(s)
- Veronica Jimenez
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, 30602, USA.,Department of Biological Science, California State University Fullerton, Fullerton, CA, 92831b, USA
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, Georgia, 30602, USA
| |
Collapse
|
33
|
Bobeck EA, Hellestad EM, Sand JM, Piccione ML, Bishop JW, Helvig C, Petkovich M, Cook ME. Oral peptide specific egg antibody to intestinal sodium-dependent phosphate co-transporter-2b is effective at altering phosphate transport in vitro and in vivo. Poult Sci 2015; 94:1128-37. [DOI: 10.3382/ps/pev085] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/10/2015] [Indexed: 11/20/2022] Open
|
34
|
Huber K, Zeller E, Rodehutscord M. Modulation of small intestinal phosphate transporter by dietary supplements of mineral phosphorus and phytase in broilers. Poult Sci 2015; 94:1009-17. [PMID: 25834252 DOI: 10.3382/ps/pev065] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/08/2015] [Indexed: 01/01/2023] Open
Abstract
Dietary phosphorus (P) is known as a main modulator of phosphate (Pi) transporter expression. The effect of supplemented mineral P with or without phytase on protein expression of two sodium-dependent Pi (NaPi) transporters and a calcium channel was studied in the small intestine of broilers. Thirty-six broilers were randomly assigned to six different diets at 15 days of age. Two levels of total P (tP, adjusted by monocalcium phosphate (MCP) supplementation), 0.39% (BD-) and 0.47% (BD+) were fed until day 25; and at each tP level, three levels of phytase were used with 0, 500, and 12,500 FTU/kg of an E. coli phytase. Mucosa samples from jejunum and ileum were taken and apical membranes were isolated by MgCl2 precipitation. Protein expression of NaPi IIb, NaPi type III (PiT1) and the calcium channel TRPV6 were semiquantitatively measured by Western blotting and jejunal mucosal phytase activity by measurement of Pi release. The jejunal NaPi IIb transporter was expressed with two distinct bands, which were modulated differently by diet. NaPi IIb Band1 increased (P < 0.05) and Band2 decreased (P < 0.05) with phytase supplementation but was not affected by MCP supplementation. This inverse modulation of Band1 and Band2 was significantly related to the amount of net absorbed P with higher expression of Band1 at higher amounts of net absorbed P. In addition, a second Pi transporter, PiT1, was detected in which ileal expression decreased (P < 0.05) in response to higher phytase supplementation. The expression of the calcium channel TRPV6 was increased in BD+ groups. A trend for an interaction between MCP and phytase supplementation on mucosal phytase activity was observed (P = 0.079) with a decrease in activity when BD+ with 12,500 FTU/kg phytase was fed. Chicken intestinal epithelial cells responded to dietary supplemented phytase and MCP by changing the Pi transporter expression in apical membranes. In conclusion, availability of Pi is most likely the key modulator of transporter protein expression. However, a contribution of lower inositol phosphates generated by phytases and other phosphatases may also be relevant.
Collapse
Affiliation(s)
- Korinna Huber
- Physiologisches Institut, Tierärztliche Hochschule, 30173 Hannover, Germany
| | - Ellen Zeller
- Institut für Tierernährung, Universität Hohenheim, 70599 Stuttgart, Germany
| | | |
Collapse
|
35
|
Abstract
Chronic kidney disease (CKD) is an important global health problem that affects 8-15% of the population according to epidemiological studies done in different countries. Essential to prevention is the knowledge of the environmental factors associated with this disease, and heavy metals such as lead and cadmium are clearly associated with kidney injury and CKD progression. Arsenic is one of the most abundant contaminants in water and soil, and many epidemiological studies have found an association between arsenic and type 2 diabetes mellitus, hypertension and cancer; however, there is a scarcity of epidemiological studies about its association with kidney disease, and the evidence linking urinary arsenic excretion with CKD, higher urinary excretion of low molecular proteins, albuminuria or other markers of renal in injury is still limited, and more studies are necessary to characterize the role of arsenic on renal injury and CKD progression. Global efforts to reduce arsenic exposure remain important and research is also needed to determine whether specific therapies are beneficial in susceptible populations.
Collapse
|
36
|
Chavkin NW, Chia JJ, Crouthamel MH, Giachelli CM. Phosphate uptake-independent signaling functions of the type III sodium-dependent phosphate transporter, PiT-1, in vascular smooth muscle cells. Exp Cell Res 2015; 333:39-48. [PMID: 25684711 DOI: 10.1016/j.yexcr.2015.02.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 01/06/2015] [Accepted: 02/06/2015] [Indexed: 12/26/2022]
Abstract
Vascular calcification (VC) is prevalent in chronic kidney disease and elevated serum inorganic phosphate (Pi) is a recognized risk factor. The type III sodium-dependent phosphate transporter, PiT-1, is required for elevated Pi-induced osteochondrogenic differentiation and matrix mineralization in vascular smooth muscle cells (VSMCs). However, the molecular mechanism(s) by which PiT-1 promotes these processes is unclear. In the present study, we confirmed that the Pi concentration required to induce osteochondrogenic differentiation and matrix mineralization of mouse VSMCs was well above that required for maximal Pi uptake, suggesting a signaling function of PiT-1 that was independent of Pi transport. Elevated Pi-induced signaling via ERK1/2 phosphorylation was abrogated in PiT-1 deficient VSMCs, but could be rescued by wild-type (WT) and a Pi transport-deficient PiT-1 mutant. Furthermore, both WT and transport-deficient PiT-1 mutants promoted osteochondrogenic differentiation as measured by decreased SM22α and increased osteopontin mRNA expression. Finally, compared to vector alone, expression of transport-deficient PiT-1 mutants promoted VSMC matrix mineralization, but not to the extent observed with PiT-1 WT. These data suggest that both Pi uptake-dependent and -independent functions of PiT-1 are important for VSMC processes mediating vascular calcification.
Collapse
Affiliation(s)
- Nicholas W Chavkin
- Department of Bioengineering, University of Washington, Box 355061, Foege Hall Seattle, WA 98195, USA
| | - Jia Jun Chia
- Department of Bioengineering, University of Washington, Box 355061, Foege Hall Seattle, WA 98195, USA
| | - Matthew H Crouthamel
- Department of Bioengineering, University of Washington, Box 355061, Foege Hall Seattle, WA 98195, USA
| | - Cecilia M Giachelli
- Department of Bioengineering, University of Washington, Box 355061, Foege Hall Seattle, WA 98195, USA.
| |
Collapse
|
37
|
Shao XM, Kao L, Kurtz I. A novel delta current method for transport stoichiometry estimation. BMC BIOPHYSICS 2015; 7:14. [PMID: 25558372 PMCID: PMC4274721 DOI: 10.1186/s13628-014-0014-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 11/19/2014] [Indexed: 11/23/2022]
Abstract
Background The ion transport stoichiometry (q) of electrogenic transporters is an important determinant of their function. q can be determined by the reversal potential (Erev) if the transporter under study is the only electrogenic transport mechanism or a specific inhibitor is available. An alternative approach is to calculate delta reversal potential (ΔErev) by altering the concentrations of the transported substrates. This approach is based on the hypothesis that the contributions of other channels and transporters on the membrane to Erev are additive. However, Erev is a complicated function of the sum of different conductances rather than being additive. Results We propose a new delta current (ΔI) method based on a simplified model for electrogenic secondary active transport by Heinz (Electrical Potentials in Biological Membrane Transport, 1981). ΔI is the difference between two currents obtained from altering the external concentration of a transported substrate thereby eliminating other currents without the need for a specific inhibitor. q is determined by the ratio of ΔI at two different membrane voltages (V1 and V2) where q = 2RT/(F(V2 –V1))ln(ΔI2/ΔI1) + 1. We tested this ΔI methodology in HEK-293 cells expressing the elctrogenic SLC4 sodium bicarbonate cotransporters NBCe2-C and NBCe1-A, the results were consistent with those obtained with the Erev inhibitor method. Furthermore, using computational simulations, we compared the estimates of q with the ΔErev and ΔI methods. The results showed that the ΔErev method introduces significant error when other channels or electrogenic transporters are present on the membrane and that the ΔI equation accurately calculates the stoichiometric ratio. Conclusions We developed a ΔI method for estimating transport stoichiometry of electrogenic transporters based on the Heinz model. This model reduces to the conventional reversal potential method when the transporter under study is the only electrogenic transport process in the membrane. When there are other electrogenic transport pathways, ΔI method eliminates their contribution in estimating q. Computational simulations demonstrated that the ΔErev method introduces significant error when other channels or electrogenic transporters are present and that the ΔI equation accurately calculates the stoichiometric ratio. This new ΔI method can be readily extended to the analysis of other electrogenic transporters in other tissues.
Collapse
Affiliation(s)
- Xuesi M Shao
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 USA
| | - Liyo Kao
- Division of Nephrology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 USA
| | - Ira Kurtz
- Division of Nephrology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 USA ; Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 USA
| |
Collapse
|
38
|
Blaine J, Chonchol M, Levi M. Renal control of calcium, phosphate, and magnesium homeostasis. Clin J Am Soc Nephrol 2014; 10:1257-72. [PMID: 25287933 DOI: 10.2215/cjn.09750913] [Citation(s) in RCA: 394] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Calcium, phosphate, and magnesium are multivalent cations that are important for many biologic and cellular functions. The kidneys play a central role in the homeostasis of these ions. Gastrointestinal absorption is balanced by renal excretion. When body stores of these ions decline significantly, gastrointestinal absorption, bone resorption, and renal tubular reabsorption increase to normalize their levels. Renal regulation of these ions occurs through glomerular filtration and tubular reabsorption and/or secretion and is therefore an important determinant of plasma ion concentration. Under physiologic conditions, the whole body balance of calcium, phosphate, and magnesium is maintained by fine adjustments of urinary excretion to equal the net intake. This review discusses how calcium, phosphate, and magnesium are handled by the kidneys.
Collapse
Affiliation(s)
- Judith Blaine
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Michel Chonchol
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Moshe Levi
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, Aurora, Colorado
| |
Collapse
|
39
|
Kongsfelt IB, Byskov K, Pedersen LE, Pedersen L. High levels of the type III inorganic phosphate transporter PiT1 (SLC20A1) can confer faster cell adhesion. Exp Cell Res 2014; 326:57-67. [PMID: 24880124 DOI: 10.1016/j.yexcr.2014.05.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Revised: 05/18/2014] [Accepted: 05/20/2014] [Indexed: 01/16/2023]
Abstract
The inorganic phosphate transporter PiT1 (SLC20A1) is ubiquitously expressed in mammalian cells. We recently showed that overexpression of human PiT1 was sufficient to increase proliferation of two strict density-inhibited cell lines, murine fibroblastic NIH3T3 and pre-osteoblastic MC3T3-E1 cells, and allowed the cultures to grow to higher cell densities. In addition, upon transformation NIH3T3 cells showed increased ability to form colonies in soft agar. The cellular regulation of PiT1 expression supports that cells utilize the PiT1 levels to control proliferation, with non-proliferating cells showing the lowest PiT1 mRNA levels. The mechanism behind the role of PiT1 in increased cell proliferation is not known. We, however, found that compared to control cells, cultures of NIH3T3 cells overexpressing PiT1 upon seeding showed increased cell number after 24h and had shifted more cells from G0/G1 to S+G2/M within 12h, suggesting that an early event may play a role. We here show that expression of human PiT1 in NIH3T3 cells led to faster cell adhesion; this effect was not cell type specific in that it was also observed when expressing human PiT1 in MC3T3-E1 cells. We also show for NIH3T3 that PiT1 overexpression led to faster cell spreading. The final total numbers of attached cells did, however, not differ between cultures of PiT1 overexpressing cells and control cells of neither cell type. We suggest that the PiT1-mediated fast adhesion potentials allow the cells to go faster out of G0/G1 and thereby contribute to their proliferative advantage within the first 24h after seeding.
Collapse
Affiliation(s)
| | - Kristina Byskov
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | - Lene Pedersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Hematology, Aarhus University Hospital, Aarhus, Denmark.
| |
Collapse
|
40
|
Guerreiro PM, Bataille AM, Parker SL, Renfro JL. Active removal of inorganic phosphate from cerebrospinal fluid by the choroid plexus. Am J Physiol Renal Physiol 2014; 306:F1275-84. [PMID: 24740787 DOI: 10.1152/ajprenal.00458.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The P(i) concentration of mammalian cerebrospinal fluid (CSF) is about one-half that of plasma, a phenomenon also shown here in the spiny dogfish, Squalus acanthias. The objective of the present study was to characterize the possible role of the choroid plexus (CP) in determining CSF P(i) concentration. The large sheet-like fourth CP of the shark was mounted in Ussing chambers where unidirectional (33)P(i) fluxes revealed potent active transport from CSF to the blood side under short-circuited conditions. The flux ratio was 8:1 with an average transepithelial resistance of 87 ± 17.9 Ω·cm(2) and electrical potential difference of +0.9 ± 0.17 mV (CSF side positive). Active P(i) absorption from CSF was inhibited by 10 mM arsenate, 0.2 mM ouabain, Na(+)-free medium, and increasing the K(+) concentration from 5 to 100 mM. Li(+) stimulated transport twofold compared with Na(+)-free medium. Phosphonoformic acid (1 mM) had no effect on active P(i) transport. RT-PCR revealed both P(i) transporter (PiT)1 and PiT2 (SLC20 family) gene expression, but no Na(+)-P(i) cotransporter II (SLC34 family) expression, in the shark CP. PiT2 immunoreactivity was shown by immunoblot analysis and localized by immunohistochemistry in (or near) the CP apical microvillar membranes of both the shark and rat. PiT1 appeared to be localized primarily to vascular endothelial cells. Taken together, these data indicate that the CP actively removes P(i) from CSF. This process has transport properties consistent with a PiT2, Na(+)-dependent transporter that is located in the apical region of the CP epithelium.
Collapse
Affiliation(s)
- Pedro M Guerreiro
- Centre of Marine Sciences, Universidade do Algarve, Faro, Portugal; Mount Desert Island Biological Laboratory, Salisbury Cove, Maine
| | - Amy M Bataille
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut; and
| | - Sonda L Parker
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut; and
| | - J Larry Renfro
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut; and Mount Desert Island Biological Laboratory, Salisbury Cove, Maine
| |
Collapse
|
41
|
Biber J, Murer H, Mohebbi N, Wagner C. Renal Handling of Phosphate and Sulfate. Compr Physiol 2014; 4:771-92. [DOI: 10.1002/cphy.c120031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
42
|
Molecular cloning and functional analysis of a H(+)-dependent phosphate transporter gene from the ectomycorrhizal fungus Boletus edulis in southwest China. Fungal Biol 2014; 118:453-61. [PMID: 24863474 DOI: 10.1016/j.funbio.2014.03.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 02/26/2014] [Accepted: 03/06/2014] [Indexed: 01/09/2023]
Abstract
Phosphate transporters (PTs), as entry points for phosphorus (P) in organisms, are involved in a number of P nutrition processes such as phosphate uptake, transport, and transfer. In the study, a PT gene 1632 bp long (named BePT) was cloned, identified, and functionally characterized from Boletus edulis. BePT was expected to encode a polypeptide with 543 amino acid residues. The BePT polypeptide belonged to the major facilitator superfamily and showed a high degree of sequence identity to the Pht1 family. A topology model revealed that BePT exhibited 12 transmembrane helices, divided into two halves, and connected by a large hydrophilic loop in the middle. A yeast mutant complementation analysis suggested that BePT was a functional PT which mediated orthophosphate uptake of yeast at micromolar concentrations. Green fluorescent protein-BePT fusion proteins expressed were extensively restricted to the plasma membrane in BePT transformed yeast, and its activity was dependent on electrochemical membrane potential. In vitro, quantitative PCR confirmed that the expression of BePT was significantly upregulated at lower phosphorus availability, which may enhance phosphate uptake and transport under phosphate starvation. Our results suggest that BePT plays a key role in phosphate acquisition in the ectomycorrhizal fungus B. edulis.
Collapse
|
43
|
Shobeiri N, Adams MA, Holden RM. Phosphate: an old bone molecule but new cardiovascular risk factor. Br J Clin Pharmacol 2014; 77:39-54. [PMID: 23506202 PMCID: PMC3895346 DOI: 10.1111/bcp.12117] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 02/21/2013] [Indexed: 12/24/2022] Open
Abstract
Phosphate handling in the body is complex and involves hormones produced by the bone, the parathyroid gland and the kidneys. Phosphate is mostly found in hydroxyapatite. however recent evidence suggests that phosphate is also a signalling molecule associated with bone formation. Phosphate balance requires careful regulation of gut and kidney phosphate transporters, SLC34 transporter family, but phosphate signalling in osteoblasts and vascular smooth muscle cells is likely mediated by the SLC20 transporter family (PiT1 and PiT2). If not properly regulated, phosphate imblanace could lead to mineral disorders as well as vascular calcification. In chronic kidney disease-mineral bone disorder, hyperphosphataemia has been consistently associated with extra-osseous calcification and cardiovascular disease. This review focuses on the physiological mechanisms involved in phosphate balance and cell signalling (i.e. osteoblasts and vascular smooth muscle cells) as well as pathological consequences of hyperphosphataemia. Finally, conventional as well as new and experimental therapeutics in the treatment of hyperphosphataemia are explored.
Collapse
Affiliation(s)
- Navid Shobeiri
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | | | | |
Collapse
|
44
|
Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: transporters. Br J Pharmacol 2013; 170:1706-96. [PMID: 24528242 PMCID: PMC3892292 DOI: 10.1111/bph.12450] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Transporters are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
Collapse
Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| |
Collapse
|
45
|
Crouthamel MH, Lau WL, Leaf EM, Chavkin NW, Wallingford MC, Peterson DF, Li X, Liu Y, Chin MT, Levi M, Giachelli CM. Sodium-dependent phosphate cotransporters and phosphate-induced calcification of vascular smooth muscle cells: redundant roles for PiT-1 and PiT-2. Arterioscler Thromb Vasc Biol 2013; 33:2625-32. [PMID: 23968976 DOI: 10.1161/atvbaha.113.302249] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Elevated serum phosphate has emerged as a major risk factor for vascular calcification. The sodium-dependent phosphate cotransporter, PiT-1, was previously shown to be required for phosphate-induced osteogenic differentiation and calcification of cultured human vascular smooth muscle cells (VSMCs), but its importance in vascular calcification in vivo and the potential role of its homologue, PiT-2, have not been determined. We investigated the in vivo requirement for PiT-1 in vascular calcification using a mouse model of chronic kidney disease and the potential compensatory role of PiT-2 using in vitro knockdown and overexpression strategies. APPROACH AND RESULTS Mice with targeted deletion of PiT-1 in VSMCs were generated (PiT-1(Δsm)). PiT-1 mRNA levels were undetectable, whereas PiT-2 mRNA levels were increased 2-fold in the vascular aortic media of PiT-1(Δsm) compared with PiT-1(flox/flox) control. When arterial medial calcification was induced in PiT-1(Δsm) and PiT-1(flox/flox) by chronic kidney disease followed by dietary phosphate loading, the degree of aortic calcification was not different between genotypes, suggesting compensation by PiT-2. Consistent with this possibility, VSMCs isolated from PiT-1(Δsm) mice had no PiT-1 mRNA expression, increased PiT-2 mRNA levels, and no difference in sodium-dependent phosphate uptake or phosphate-induced matrix calcification compared with PiT-1(flox/flox) VSMCs. Knockdown of PiT-2 decreased phosphate uptake and phosphate-induced calcification of PiT-1(Δsm) VSMCs. Furthermore, overexpression of PiT-2 restored these parameters in human PiT-1-deficient VSMCs. CONCLUSIONS PiT-2 can mediate phosphate uptake and calcification of VSMCs in the absence of PiT-1. Mechanistically, PiT-1 and PiT-2 seem to serve redundant roles in phosphate-induced calcification of VSMCs.
Collapse
Affiliation(s)
- Matthew H Crouthamel
- From the Departments of Bioengineering (M.H.C., E.M.L., N.W.C., M.C.W., D.F.P., X.L., C.M.G.), Nephrology (W.L.L.), and Cardiology (Y.L., M.T.C.), University of Washington, Seattle; and Department of Medicine, University of Colorado, Denver (M.L.)
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Bourgine A, Pilet P, Diouani S, Sourice S, Lesoeur J, Beck-Cormier S, Khoshniat S, Weiss P, Friedlander G, Guicheux J, Beck L. Mice with hypomorphic expression of the sodium-phosphate cotransporter PiT1/Slc20a1 have an unexpected normal bone mineralization. PLoS One 2013; 8:e65979. [PMID: 23785462 PMCID: PMC3681848 DOI: 10.1371/journal.pone.0065979] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 05/03/2013] [Indexed: 11/18/2022] Open
Abstract
The formation of hydroxyapatite crystals and their insertion into collagen fibrils of the matrix are essential steps for bone mineralization. As phosphate is a main structural component of apatite crystals, its uptake by skeletal cells is critical and must be controlled by specialized membrane proteins. In mammals, in vitro studies have suggested that the high-affinity sodium-phosphate cotransporter PiT1 could play this role. In vivo, PiT1 expression was detected in hypertrophic chondrocytes of murine metatarsals, but its implication in bone physiology is not yet deciphered. As the complete deletion of PiT1 results in embryonic lethality at E12.5, we took advantage of a mouse model bearing two copies of PiT1 hypomorphic alleles to study the effect of a low expression of PiT1 on bone mineralization in vivo. In this report, we show that a 85% down-regulation of PiT1 in long bones resulted in a slight (6%) but significant reduction of femur length in young mice (15- and 30-day-old). However, despite a defect in alcian blue / alizarin red S and Von Kossa staining of hypomorphic 1-day-old mice, using X-rays micro-computed tomography, energy dispersive X-ray spectroscopy and histological staining techniques we could not detect differences between hypomorphic and wild-type mice of 15- to 300-days old. Interestingly, the expression of PiT2, the paralog of PiT1, was increased 2-fold in bone of PiT1 hypomorphic mice accounting for a normal phosphate uptake in mutant cells. Whether this may contribute to the absence of bone mineralization defects remains to be further deciphered.
Collapse
Affiliation(s)
- Annabelle Bourgine
- Institut National de la Sante et de la recherche Medicale, U791, LIOAD, STEP group "Skeletal Tissue Engineering and Physiopathology”, Nantes, France
- Université de Nantes, UFR Odontologie, Nantes, France
| | - Paul Pilet
- Institut National de la Sante et de la recherche Medicale, U791, LIOAD, STEP group "Skeletal Tissue Engineering and Physiopathology”, Nantes, France
- Université de Nantes, UFR Odontologie, Nantes, France
| | - Sara Diouani
- Institut National de la Sante et de la recherche Medicale, U845, Centre de Recherche Croissance et Signalisation, Paris, France
- Université Paris Descartes, Paris, France
| | - Sophie Sourice
- Institut National de la Sante et de la recherche Medicale, U791, LIOAD, STEP group "Skeletal Tissue Engineering and Physiopathology”, Nantes, France
- Université de Nantes, UFR Odontologie, Nantes, France
| | - Julie Lesoeur
- Institut National de la Sante et de la recherche Medicale, U791, LIOAD, STEP group "Skeletal Tissue Engineering and Physiopathology”, Nantes, France
- Université de Nantes, UFR Odontologie, Nantes, France
| | - Sarah Beck-Cormier
- Institut National de la Sante et de la recherche Medicale, U791, LIOAD, STEP group "Skeletal Tissue Engineering and Physiopathology”, Nantes, France
- Université de Nantes, UFR Odontologie, Nantes, France
| | - Solmaz Khoshniat
- Institut National de la Sante et de la recherche Medicale, U791, LIOAD, STEP group "Skeletal Tissue Engineering and Physiopathology”, Nantes, France
- Université de Nantes, UFR Odontologie, Nantes, France
| | - Pierre Weiss
- Institut National de la Sante et de la recherche Medicale, U791, LIOAD, STEP group "Skeletal Tissue Engineering and Physiopathology”, Nantes, France
- Université de Nantes, UFR Odontologie, Nantes, France
| | - Gérard Friedlander
- Institut National de la Sante et de la recherche Medicale, U845, Centre de Recherche Croissance et Signalisation, Paris, France
- Université Paris Descartes, Paris, France
| | - Jérôme Guicheux
- Institut National de la Sante et de la recherche Medicale, U791, LIOAD, STEP group "Skeletal Tissue Engineering and Physiopathology”, Nantes, France
- Université de Nantes, UFR Odontologie, Nantes, France
| | - Laurent Beck
- Institut National de la Sante et de la recherche Medicale, U791, LIOAD, STEP group "Skeletal Tissue Engineering and Physiopathology”, Nantes, France
- Université de Nantes, UFR Odontologie, Nantes, France
- * E-mail:
| |
Collapse
|
47
|
The phosphate transporter NaPi-IIa determines the rapid renal adaptation to dietary phosphate intake in mouse irrespective of persistently high FGF23 levels. Pflugers Arch 2013; 465:1557-72. [PMID: 23708836 DOI: 10.1007/s00424-013-1298-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 05/03/2013] [Accepted: 05/13/2013] [Indexed: 01/13/2023]
Abstract
Renal reabsorption of inorganic phosphate (Pi) is mediated by the phosphate transporters NaPi-IIa, NaPi-IIc, and Pit-2 in the proximal tubule brush border membrane (BBM). Dietary Pi intake regulates these transporters; however, the contribution of the specific isoforms to the rapid and slow phase is not fully clarified. Moreover, the regulation of PTH and FGF23, two major phosphaturic hormones, during the adaptive phase has not been correlated. C57/BL6 and NaPi-IIa(-/-) mice received 5 days either 1.2 % (HPD) or 0.1 % (LPD) Pi-containing diets. Thereafter, some mice were acutely switched to LPD or HPD. Plasma Pi concentrations were similar under chronic diets, but lower when mice were acutely switched to LPD. Urinary Pi excretion was similar in C57/BL6 and NaPi-IIa(-/-) mice under HPD. During chronic LPD, NaPi-IIa(-/-) mice lost phosphate in urine compensated by higher intestinal Pi absorption. During the acute HPD-to-LPD switch, NaPi-IIa(-/-) mice exhibited a delayed decrease in urinary Pi excretion. PTH was acutely regulated by low dietary Pi intake. FGF23 did not respond to low Pi intake within 8 h whereas the phospho-adaptator protein FRS2α necessary for FGF-receptor cell signaling was downregulated. BBM Pi transport activity and NaPi-IIa but not NaPi-IIc and Pit-2 abundance acutely adapted to diets in C57/BL6 mice. In NaPi-IIa(-/-), Pi transport activity was low and did not adapt. Thus, NaPi-IIa mediates the fast adaptation to Pi intake and is upregulated during the adaptation to low Pi despite persistently high FGF23 levels. The sensitivity to FGF23 may be regulated by adapting FRS2α abundance and phosphorylation.
Collapse
|
48
|
Affiliation(s)
- Jürg Biber
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, CH-8057 Zurich, Switzerland; , ,
| | - Nati Hernando
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, CH-8057 Zurich, Switzerland; , ,
| | - Ian Forster
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, CH-8057 Zurich, Switzerland; , ,
| |
Collapse
|
49
|
Haller M, Amatschek S, Wilflingseder J, Kainz A, Bielesz B, Pavik I, Serra A, Mohebbi N, Biber J, Wagner CA, Oberbauer R. Sirolimus induced phosphaturia is not caused by inhibition of renal apical sodium phosphate cotransporters. PLoS One 2012; 7:e39229. [PMID: 22859939 PMCID: PMC3408497 DOI: 10.1371/journal.pone.0039229] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 05/17/2012] [Indexed: 12/01/2022] Open
Abstract
The vast majority of glomerular filtrated phosphate is reabsorbed in the proximal tubule. Posttransplant phosphaturia is common and aggravated by sirolimus immunosuppression. The cause of sirolimus induced phosphaturia however remains elusive. Male Wistar rats received sirolimus or vehicle for 2 or 7 days (1.5mg/kg). The urine phosphate/creatinine ratio was higher and serum phosphate was lower in sirolimus treated rats, fractional excretion of phosphate was elevated and renal tubular phosphate reabsorption was reduced suggesting a renal cause for hypophosphatemia. PTH was lower in sirolimus treated rats. FGF 23 levels were unchanged at day 2 but lower in sirolimus treated rats after 7 days. Brush border membrane vesicle phosphate uptake was not altered in sirolimus treated groups or by direct incubation with sirolimus. mRNA, protein abundance, and subcellular transporter distribution of NaPi-IIa, Pit-2 and NHE3 were not different between groups but NaPi-IIc mRNA expression was lower at day 7. Transcriptome analyses revealed candidate genes that could be involved in the phosphaturic response. Sirolimus caused a selective renal phosphate leakage, which was not mediated by NaPi-IIa or NaPi-IIc regulation or localization. We hypothesize that another mechanism such as a basolateral phosphate transporter may be responsible for the sirolimus induced phosphaturia.
Collapse
Affiliation(s)
- Maria Haller
- Department of Nephrology, Medical University of Vienna, Vienna, Austria
- Institute of Physiology, Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Department of Nephrology and Transplantation, KH Elisabethinen Linz, Linz, Austria
| | - Stefan Amatschek
- Department of Nephrology, Medical University of Vienna, Vienna, Austria
| | | | - Alexander Kainz
- Department of Nephrology, Medical University of Vienna, Vienna, Austria
| | - Bernd Bielesz
- Department of Nephrology, Medical University of Vienna, Vienna, Austria
| | - Ivana Pavik
- Institute of Physiology, Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Andreas Serra
- Institute of Physiology, Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Nilufar Mohebbi
- Institute of Physiology, Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Jürg Biber
- Institute of Physiology, Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Carsten A. Wagner
- Institute of Physiology, Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Rainer Oberbauer
- Department of Nephrology, Medical University of Vienna, Vienna, Austria
- Department of Nephrology and Transplantation, KH Elisabethinen Linz, Linz, Austria
- Austrian Dialysis and Transplant Registry, Linz, Austria
- * E-mail:
| |
Collapse
|
50
|
Schaffhauser DF, Patti M, Goda T, Miyahara Y, Forster IC, Dittrich PS. An integrated field-effect microdevice for monitoring membrane transport in Xenopus laevis oocytes via lateral proton diffusion. PLoS One 2012; 7:e39238. [PMID: 22792166 PMCID: PMC3390327 DOI: 10.1371/journal.pone.0039238] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 05/17/2012] [Indexed: 11/18/2022] Open
Abstract
An integrated microdevice for measuring proton-dependent membrane activity at the surface of Xenopus laevis oocytes is presented. By establishing a stable contact between the oocyte vitelline membrane and an ion-sensitive field-effect (ISFET) sensor inside a microperfusion channel, changes in surface pH that are hypothesized to result from facilitated proton lateral diffusion along the membrane were detected. The solute diffusion barrier created between the sensor and the active membrane area allowed detection of surface proton concentration free from interference of solutes in bulk solution. The proposed sensor mechanism was verified by heterologously expressing membrane transport proteins and recording changes in surface pH during application of the specific substrates. Experiments conducted on two families of phosphate-sodium cotransporters (SLC20 & SLC34) demonstrated that it is possible to detect phosphate transport for both electrogenic and electroneutral isoforms and distinguish between transport of different phosphate species. Furthermore, the transport activity of the proton/amino acid cotransporter PAT1 assayed using conventional whole cell electrophysiology correlated well with changes in surface pH, confirming the ability of the system to detect activity proportional to expression level.
Collapse
Affiliation(s)
| | - Monica Patti
- Institute for Physiology, University of Zurich, Zurich, Switzerland
| | - Tatsuro Goda
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yuji Miyahara
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
- * E-mail: (PSD); (ICF); (YM)
| | - Ian Cameron Forster
- Institute for Physiology, University of Zurich, Zurich, Switzerland
- * E-mail: (PSD); (ICF); (YM)
| | - Petra Stephanie Dittrich
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
- * E-mail: (PSD); (ICF); (YM)
| |
Collapse
|