1
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Poulsen SB, Murali SK, Thomas L, Assmus A, Rosenbæk LL, Nielsen R, Dimke H, Rieg T, Fenton RA. Genetic deletion of the kidney sodium/proton exchanger-3 (NHE3) does not alter calcium and phosphate balance due to compensatory responses. Kidney Int 2025; 107:280-295. [PMID: 39089578 DOI: 10.1016/j.kint.2024.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 06/10/2024] [Accepted: 07/02/2024] [Indexed: 08/04/2024]
Abstract
The sodium/proton exchanger-3 (NHE3) plays a major role in acid-base and extracellular volume regulation and is also implicated in calcium homeostasis. As calcium and phosphate balances are closely linked, we hypothesized that there was a functional link between kidney NHE3 activity, calcium, and phosphate balance. Therefore, we examined calcium and phosphate homeostasis in kidney tubule-specific NHE3 knockout mice (NHE3loxloxPax8 mice). Compared to controls, these knockout mice were normocalcemic with no significant difference in urinary calcium excretion or parathyroid hormone levels. Thiazide-induced hypocalciuria was less pronounced in the knockout mice, in line with impaired proximal tubule calcium transport. Knockout mice had greater furosemide-induced calciuresis and distal tubule calcium transport pathways were enhanced. Despite lower levels of the sodium/phosphate cotransporters (NaPi)-2a and -2c, knockout mice had normal plasma phosphate, sodium-dependent 32Phosphate uptake in proximal tubule membrane vesicles and urinary phosphate excretion. Intestinal phosphate uptake was unchanged. Low dietary phosphate reduced parathyroid hormone levels and increased NaPi-2a and -2c abundances in both genotypes, but NaPi-2c levels remained lower in the knockout mice. Gene expression profiling suggested proximal tubule remodeling in the knockout mice. Acutely, indirect NHE3 inhibition using the SGLT2 inhibitor empagliflozin did not affect urinary calcium and phosphate excretion. No differences in femoral bone density or architecture were detectable in the knockout mice. Thus, a role for kidney NHE3 in calcium homeostasis can be unraveled by diuretics, but NHE3 deletion in the kidneys has no major effects on overall calcium and phosphate homeostasis due, at least in part, to compensating mechanisms.
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Affiliation(s)
- Søren B Poulsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Sathish K Murali
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Linto Thomas
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida, USA
| | - Adrienne Assmus
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Lena L Rosenbæk
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Rikke Nielsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark; Department of Nephrology, Odense University Hospital, Odense, Denmark
| | - Timo Rieg
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida, USA; James A. Haley Veterans' Hospital, Tampa, Florida, USA.
| | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
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2
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Walker V. The Intricacies of Renal Phosphate Reabsorption-An Overview. Int J Mol Sci 2024; 25:4684. [PMID: 38731904 PMCID: PMC11083860 DOI: 10.3390/ijms25094684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2024] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 05/13/2024] Open
Abstract
To maintain an optimal body content of phosphorus throughout postnatal life, variable phosphate absorption from food must be finely matched with urinary excretion. This amazing feat is accomplished through synchronised phosphate transport by myriads of ciliated cells lining the renal proximal tubules. These respond in real time to changes in phosphate and composition of the renal filtrate and to hormonal instructions. How they do this has stimulated decades of research. New analytical techniques, coupled with incredible advances in computer technology, have opened new avenues for investigation at a sub-cellular level. There has been a surge of research into different aspects of the process. These have verified long-held beliefs and are also dramatically extending our vision of the intense, integrated, intracellular activity which mediates phosphate absorption. Already, some have indicated new approaches for pharmacological intervention to regulate phosphate in common conditions, including chronic renal failure and osteoporosis, as well as rare inherited biochemical disorders. It is a rapidly evolving field. The aim here is to provide an overview of our current knowledge, to show where it is leading, and where there are uncertainties. Hopefully, this will raise questions and stimulate new ideas for further research.
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Affiliation(s)
- Valerie Walker
- Department of Clinical Biochemistry, University Hospital Southampton NHS Foundation Trust, Southampton General Hospital, Southampton S016 6YD, UK
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3
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Lucea S, Chopo-Escuin G, Guillén N, Sosa C, Sorribas V. Intestinal and Renal Adaptations to Changes of Dietary Phosphate Concentrations in Rat. FUNCTION 2023; 5:zqad063. [PMID: 38033458 PMCID: PMC10686248 DOI: 10.1093/function/zqad063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 11/05/2023] [Accepted: 11/07/2023] [Indexed: 12/02/2023] Open
Abstract
We have studied the role of the intestine, kidney, and several hormones when adapting to changes in dietary P concentration. Normal and parathyroidectomized (PTX) rats were fed pH-matched diets containing 0.1%, 0.6%, and 1.2% P concentrations. 32Pi uptake was determined in the jejunum and kidney cortex brush border membrane vesicles. Several hormone and ion concentrations were determined in the blood and urine of rats. Both jejunum and kidney cortex Pi transport was regulated with 5 d of chronic feeding of P diets in normal rats. Acute adaptation was determined by switching foods on day 6, which was only clearly observed in the kidney cortex of normal rats, with more statistical variability in the jejunum. However, no paradoxical increase of Pi uptake in the jejunum was reproduced after the acute switch to the 1.2% P diet. Pi uptake in the jejunum was parathyroid hormone (PTH)-independent, but in the kidney, the chronic adaptation was reduced, and no acute dietary adaptations were observed. The NaPi2a protein was more abundant in the PTX than the sham kidneys, but contrary to the modest or absent changes in Pi uptake adaptation, the transporter was similarly regulated by dietary P, as in the sham rats. PTH and fibroblast growth factor 23 (FGF23) were the only hormones regulated by all diet changes, even in fasting animals, which exhibited regulated Pi transport despite similar phosphatemia. Evidence of Pi appetite effects was also observed. In brief, our results show new characteristics of Pi adaptations, including a lack of correlation between Pi transport, NaPi2a expression, and PTH/FGF23 concentrations.
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Affiliation(s)
- Susana Lucea
- Laboratory of Molecular Toxicology, Department of Biochemistry and Cell and Molecular Biology, University of Zaragoza, E50013 Zaragoza, Spain
| | - Gema Chopo-Escuin
- Laboratory of Molecular Toxicology, Department of Biochemistry and Cell and Molecular Biology, University of Zaragoza, E50013 Zaragoza, Spain
| | - Natalia Guillén
- Laboratory of Molecular Toxicology, Department of Biochemistry and Cell and Molecular Biology, University of Zaragoza, E50013 Zaragoza, Spain
| | - Cecilia Sosa
- Laboratory of Molecular Toxicology, Department of Biochemistry and Cell and Molecular Biology, University of Zaragoza, E50013 Zaragoza, Spain
| | - Víctor Sorribas
- Laboratory of Molecular Toxicology, Department of Biochemistry and Cell and Molecular Biology, University of Zaragoza, E50013 Zaragoza, Spain
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4
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Schönauer R, Scherer L, Nemitz-Kliemchen M, Hagemann T, Hantmann E, Seidel A, Müller L, Kehr S, Voigt C, Stolzenburg JU, Halbritter J. Systematic assessment of monogenic etiology in adult-onset kidney stone formers undergoing urological intervention-evidence for genetic pretest probability. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2022; 190:279-288. [PMID: 35923129 DOI: 10.1002/ajmg.c.31991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 06/08/2022] [Accepted: 07/14/2022] [Indexed: 01/29/2023]
Abstract
Kidney stone disease (KSD) is a prevalent condition associated with high morbidity, frequent recurrence, and progression to chronic kidney disease (CKD). The etiology is multifactorial, depending on environmental and genetic factors. Although monogenic KSD is frequent in children, unbiased prevalence data of heritable forms in adults is scarce. Within 2 years of recruitment, all patients hospitalized for urological kidney stone intervention at our center were consecutively enrolled for targeted next generation sequencing (tNGS). Additionally, clinical and metabolic assessments were performed for genotype-phenotype analyses. The cohort comprised 155 (66%) males and 81 (34%) females, with a mean age at first stone of 47 years (4-86). The diagnostic yield of tNGS was 6.8% (16/236), with cystinuria (SLC3A1, SLC7A9), distal renal tubular acidosis (SLC4A1), and renal phosphate wasting (SLC34A1, SLC9A3R1) as underlying hereditary disorders. While metabolic syndrome traits were associated with late-onset KSD, hereditary KSD was associated with increased disease severity in terms of early-onset, frequent recurrence, mildly impaired kidney function, and common bilateral affection. By employing systematic genetic analysis to a less biased cohort of common adult kidney stone formers, we demonstrate its diagnostic value for establishing the underlying disorder in a distinct proportion. Factors determining pretest probability include age at first stone (<40 years), frequent recurrence, mild CKD, and bilateral KSD.
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Affiliation(s)
- Ria Schönauer
- Department of Nephrology, Charité Universitätsmedizin Berlin, Berlin, Germany.,Division of Nephrology, University of Leipzig Medical Center, Leipzig, Germany
| | - Lotte Scherer
- Division of Nephrology, University of Leipzig Medical Center, Leipzig, Germany
| | - Melanie Nemitz-Kliemchen
- Department of Nephrology, Charité Universitätsmedizin Berlin, Berlin, Germany.,Division of Nephrology, University of Leipzig Medical Center, Leipzig, Germany
| | - Tobias Hagemann
- Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Helmholtz-Institut für Metabolismus-Adipositas-und Gefäßforschung (HI-MAG), Leipzig, Germany.,Interdisziplinäres Zentrum für Bioinformatik (IZBI), University of Leipzig, Leipzig, Germany
| | - Elena Hantmann
- Department of Nephrology, Charité Universitätsmedizin Berlin, Berlin, Germany.,Division of Nephrology, University of Leipzig Medical Center, Leipzig, Germany
| | - Anna Seidel
- Division of Nephrology, University of Leipzig Medical Center, Leipzig, Germany
| | - Luise Müller
- Division of Nephrology, University of Leipzig Medical Center, Leipzig, Germany
| | - Stephanie Kehr
- Interdisziplinäres Zentrum für Bioinformatik (IZBI), University of Leipzig, Leipzig, Germany
| | - Cornelia Voigt
- Department of Urology, University of Leipzig Medical Center, Leipzig, Germany
| | | | - Jan Halbritter
- Department of Nephrology, Charité Universitätsmedizin Berlin, Berlin, Germany.,Division of Nephrology, University of Leipzig Medical Center, Leipzig, Germany
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5
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Guaglianone G, Torrado B, Lin YF, Watkins MC, Wysocki VH, Gratton E, Nowick JS. Elucidating the Oligomerization and Cellular Interactions of a Trimer Derived from Aβ through Fluorescence and Mass Spectrometric Studies. ACS Chem Neurosci 2022; 13:2473-2482. [PMID: 35892278 PMCID: PMC9389591 DOI: 10.1021/acschemneuro.2c00313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/15/2022] [Indexed: 01/20/2023] Open
Abstract
Aβ oligomers play a central role in the neurodegeneration observed with Alzheimer's disease. Our laboratory has developed covalently stabilized trimers derived from residues 17-36 of Aβ as model systems for studying Aβ oligomers. In the current study, we apply the emerging techniques of fluorescence lifetime imaging microscopy (FLIM) and native mass spectrometry (native MS) to better understand the assembly and interactions of the oligomer model system 2AT-L in aqueous solutions and with cells. 2AT-L and fluorescently labeled 2AT-L analogues assemble in the membrane-like environment of SDS-PAGE, showing diffuse bands of oligomers in equilibrium. Native ion mobility-mass spectrometry (native IM-MS) of 2AT-L allows for the identification of discrete oligomers in solution and shows similar patterns of oligomer formation between 2AT-L and fluorescently labeled analogues. Fluorescence microscopy with SH-SY5Y cells reveals that fluorescently labeled 2AT-L analogues colocalize within lysosomes. FLIM studies with phasor analysis further elucidate the assembly of 2AT-L within cells and establish the occurrence of FRET, indicating the presence of oligomers within cells. Collectively, these multiple complementary techniques help better understand the complex behavior of the 2AT-L model system.
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Affiliation(s)
- Gretchen Guaglianone
- Department
of Chemistry, University of California,
Irvine, Irvine, California 92697, United States
| | - Belén Torrado
- Laboratory
for Fluorescence Dynamics, Biomedical Engineering, University of California, Irvine, California 92697, United States
| | - Yu-Fu Lin
- Resource
for Native MS Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
- Department
of Chemistry and Biochemistry, The Ohio
State University, Columbus, Ohio 43210, United States
| | - Matthew C. Watkins
- Department
of Chemistry, University of California,
Irvine, Irvine, California 92697, United States
| | - Vicki H. Wysocki
- Resource
for Native MS Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
- Department
of Chemistry and Biochemistry, The Ohio
State University, Columbus, Ohio 43210, United States
| | - Enrico Gratton
- Laboratory
for Fluorescence Dynamics, Biomedical Engineering, University of California, Irvine, California 92697, United States
| | - James S. Nowick
- Department
of Chemistry, University of California,
Irvine, Irvine, California 92697, United States
- Department
of Pharmaceutical Sciences, University of
California, Irvine, Irvine, California 92697, United States
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6
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Miyazaki-Anzai S, Keenan AL, Blaine J, Miyazaki M. Targeted Disruption of a Proximal Tubule-Specific TMEM174 Gene in Mice Causes Hyperphosphatemia and Vascular Calcification. J Am Soc Nephrol 2022; 33:1477-1486. [PMID: 35459732 PMCID: PMC9342641 DOI: 10.1681/asn.2021121578] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 04/07/2022] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The proximal tubules play a critical role in phosphate (Pi) homeostasis by reabsorbing Pi via sodium-dependent Pi cotransporters. NPT2A is a major proximal-specific Pi cotransporter, whose expression is regulated by circulating hormones, such as parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23). In this study, we aimed to find a novel regulator in Pi homeostasis. METHODS Using RNA-seq and RT-qPCR analysis, we identified proximal tubule cell-enriched genes. We next used RNAi screening of the identified proximal tubular cell-enriched genes to identify a novel proximal tubule-specific gene that contributes to FGF23- and PTH-mediated inhibition of Pi uptake and NPT2 reduction. We created mice lacking this novel regulator of Pi homeostasis to examine whether the novel regulator contributes to Pi homeostasis in vivo. RESULTS We identified 54 kidney-enriched genes, 19 of which are expressed in renal primary proximal tubule cells. One of the proximal tubule-specific genes, TMEM174, interacted with NPT2A, and its knockdown blocked the reduction of NPT2A protein by FGF23 and PTH treatments in human and opossum proximal tubule cells. TMEM174 KO mice had significantly increased levels of serum Pi, FGF23, and PTH, resulting in vascular calcification. CONCLUSIONS TMEM174 is a novel regulator of Pi homeostasis that interacts with NPT2A.
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Affiliation(s)
- Shinobu Miyazaki-Anzai
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Audrey L. Keenan
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Judith Blaine
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Makoto Miyazaki
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
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7
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D'Amico M, Di Franco E, Cerutti E, Barresi V, Condorelli D, Diaspro A, Lanzanò L. A phasor-based approach to improve optical sectioning in any confocal microscope with a tunable pinhole. Microsc Res Tech 2022; 85:3207-3216. [PMID: 35686877 PMCID: PMC9542401 DOI: 10.1002/jemt.24178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/26/2022] [Accepted: 05/29/2022] [Indexed: 01/20/2023]
Abstract
Confocal fluorescence microscopy is a well‐established imaging technique capable of generating thin optical sections of biological specimens. Optical sectioning in confocal microscopy is mainly determined by the size of the pinhole, a small aperture placed in front of a point detector. In principle, imaging with a closed pinhole provides the highest degree of optical sectioning. In practice, the dramatic reduction of signal‐to‐noise ratio (SNR) at smaller pinhole sizes makes challenging the use of pinhole sizes significantly smaller than 1 Airy Unit (AU). Here, we introduce a simple method to “virtually” perform confocal imaging at smaller pinhole sizes without the dramatic reduction of SNR. The method is based on the sequential acquisition of multiple confocal images acquired at different pinhole aperture sizes and image processing based on a phasor analysis. The implementation is conceptually similar to separation of photons by lifetime tuning (SPLIT), a technique that exploits the phasor analysis to achieve super‐resolution, and for this reason we call this method SPLIT‐pinhole (SPLIT‐PIN). We show with simulated data that the SPLIT‐PIN image can provide improved optical sectioning (i.e., virtually smaller pinhole size) but better SNR with respect to an image obtained with closed pinhole. For instance, two images acquired at 2 and 1 AU can be combined to obtain a SPLIT‐PIN image with a virtual pinhole size of 0.2 AU but with better SNR. As an example of application to biological imaging, we show that SPLIT‐PIN improves confocal imaging of the apical membrane in an in vitro model of the intestinal epithelium.
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Affiliation(s)
- Morgana D'Amico
- Department of Physics and Astronomy "Ettore Majorana", University of Catania, Catania, Italy
| | - Elisabetta Di Franco
- Department of Physics and Astronomy "Ettore Majorana", University of Catania, Catania, Italy
| | - Elena Cerutti
- Department of Physics and Astronomy "Ettore Majorana", University of Catania, Catania, Italy.,Nanoscopy, CHT Erzelli, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Vincenza Barresi
- Department of Biomedical and Biotechnological Sciences, Section of Medical Biochemistry, University of Catania, Catania, Italy
| | - Daniele Condorelli
- Department of Biomedical and Biotechnological Sciences, Section of Medical Biochemistry, University of Catania, Catania, Italy
| | - Alberto Diaspro
- Nanoscopy, CHT Erzelli, Istituto Italiano di Tecnologia, Genoa, Italy.,DIFILAB, Department of Physics, University of Genoa, Genoa, Italy
| | - Luca Lanzanò
- Department of Physics and Astronomy "Ettore Majorana", University of Catania, Catania, Italy.,Nanoscopy, CHT Erzelli, Istituto Italiano di Tecnologia, Genoa, Italy
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8
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Sasaki S, Shiozaki Y, Hanazaki A, Koike M, Tanifuji K, Uga M, Kawahara K, Kaneko I, Kawamoto Y, Wiriyasermkul P, Hasegawa T, Amizuka N, Miyamoto KI, Nagamori S, Kanai Y, Segawa H. Tmem174, a regulator of phosphate transporter prevents hyperphosphatemia. Sci Rep 2022; 12:6353. [PMID: 35428804 PMCID: PMC9012787 DOI: 10.1038/s41598-022-10409-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 04/05/2022] [Indexed: 11/23/2022] Open
Abstract
Renal type II sodium-dependent inorganic phosphate (Pi) transporters NaPi2a and NaPi2c cooperate with other organs to strictly regulate the plasma Pi concentration. A high Pi load induces expression and secretion of the phosphaturic hormones parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) that enhance urinary Pi excretion and prevent the onset of hyperphosphatemia. How FGF23 secretion from bone is increased by a high Pi load and the setpoint of the plasma Pi concentration, however, are unclear. Here, we investigated the role of Transmembrane protein 174 (Tmem174) and observed evidence for gene co-expression networks in NaPi2a and NaPi2c function. Tmem174 is localized in the renal proximal tubules and interacts with NaPi2a, but not NaPi2c. In Tmem174-knockout (KO) mice, the serum FGF23 concentration was markedly increased but increased Pi excretion and hypophosphatemia were not observed. In addition, Tmem174-KO mice exhibit reduced NaPi2a responsiveness to FGF23 and PTH administration. Furthermore, a dietary Pi load causes marked hyperphosphatemia and abnormal NaPi2a regulation in Tmem174-KO mice. Thus, Tmem174 is thought to be associated with FGF23 induction in bones and the regulation of NaPi2a to prevent an increase in the plasma Pi concentration due to a high Pi load and kidney injury.
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Affiliation(s)
- Sumire Sasaki
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Yuji Shiozaki
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Ai Hanazaki
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Megumi Koike
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Kazuya Tanifuji
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Minori Uga
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Kota Kawahara
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Ichiro Kaneko
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Yasuharu Kawamoto
- Department of Bio-System Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Pattama Wiriyasermkul
- Department of Laboratory Medicine, The Jikei University School of Medicine, Tokyo, Japan
| | - Tomoka Hasegawa
- Developmental Biology of Hard Tissue, Faculty of Dental Medicine, Hokkaido University, Sapporo, Japan
| | - Norio Amizuka
- Developmental Biology of Hard Tissue, Faculty of Dental Medicine, Hokkaido University, Sapporo, Japan
| | - Ken-Ichi Miyamoto
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan.,Graduate School of Agriculture, Ryukoku University, Ohtsu, Japan
| | - Shushi Nagamori
- Department of Laboratory Medicine, The Jikei University School of Medicine, Tokyo, Japan.
| | - Yoshikatsu Kanai
- Department of Bio-System Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan.
| | - Hiroko Segawa
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan.
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9
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Linear Combination Properties of the Phasor Space in Fluorescence Imaging. SENSORS 2022; 22:s22030999. [PMID: 35161742 PMCID: PMC8840623 DOI: 10.3390/s22030999] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 01/15/2022] [Accepted: 01/20/2022] [Indexed: 12/16/2022]
Abstract
The phasor approach to fluorescence lifetime imaging, and more recently hyperspectral fluorescence imaging, has increased the use of these techniques, and improved the ease and intuitiveness of the data analysis. The fit-free nature of the phasor plots increases the speed of the analysis and reduces the dimensionality, optimization of data handling and storage. The reciprocity principle between the real and imaginary space-where the phasor and the pixel that the phasor originated from are linked and can be converted from one another-has helped the expansion of this method. The phasor coordinates calculated from a pixel, where multiple fluorescent species are present, depends on the phasor positions of those components. The relative positions are governed by the linear combination properties of the phasor space. According to this principle, the phasor position of a pixel with multiple components lies inside the polygon whose vertices are occupied by the phasor positions of these individual components and the distance between the image phasor to any of the vertices is inversely proportional to the fractional intensity contribution of that component to the total fluorescence from that image pixel. The higher the fractional intensity contribution of a vertex, the closer is the resultant phasor. The linear additivity in the phasor space can be exploited to obtain the fractional intensity contribution from multiple species and quantify their contribution. This review details the various mathematical models that can be used to obtain two/three/four components from phasor space with known phasor signatures and then how to obtain both the fractional intensities and phasor positions without any prior knowledge of either, assuming they are mono-exponential in nature. We note that other than for blind components, there are no restrictions on the type of the decay or their phasor positions for linear combinations to be valid-and they are applicable to complicated fluorescence lifetime decays from components with intensity decays described by multi-exponentials.
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10
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Agarwal S, Sudhini YR, Polat OK, Reiser J, Altintas MM. Renal cell markers: lighthouses for managing renal diseases. Am J Physiol Renal Physiol 2021; 321:F715-F739. [PMID: 34632812 DOI: 10.1152/ajprenal.00182.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Kidneys, one of the vital organs in our body, are responsible for maintaining whole body homeostasis. The complexity of renal function (e.g., filtration, reabsorption, fluid and electrolyte regulation, and urine production) demands diversity not only at the level of cell types but also in their overall distribution and structural framework within the kidney. To gain an in depth molecular-level understanding of the renal system, it is imperative to discern the components of kidney and the types of cells residing in each of the subregions. Recent developments in labeling, tracing, and imaging techniques have enabled us to mark, monitor, and identify these cells in vivo with high efficiency in a minimally invasive manner. In this review, we summarize different cell types, specific markers that are uniquely associated with those cell types, and their distribution in the kidney, which altogether make kidneys so special and different. Cellular sorting based on the presence of certain proteins on the cell surface allowed for the assignment of multiple markers for each cell type. However, different studies using different techniques have found contradictions in cell type-specific markers. Thus, the term "cell marker" might be imprecise and suboptimal, leading to uncertainty when interpreting the data. Therefore, we strongly believe that there is an unmet need to define the best cell markers for a cell type. Although the compendium of renal-selective marker proteins presented in this review is a resource that may be useful to researchers, we acknowledge that the list may not be necessarily exhaustive.
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Affiliation(s)
- Shivangi Agarwal
- Department of Internal Medicine, Rush University, Chicago, Illinois
| | | | - Onur K Polat
- Department of Internal Medicine, Rush University, Chicago, Illinois
| | - Jochen Reiser
- Department of Internal Medicine, Rush University, Chicago, Illinois
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11
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Takemon Y, Chick JM, Gerdes Gyuricza I, Skelly DA, Devuyst O, Gygi SP, Churchill GA, Korstanje R. Proteomic and transcriptomic profiling reveal different aspects of aging in the kidney. eLife 2021; 10:e62585. [PMID: 33687326 PMCID: PMC8096428 DOI: 10.7554/elife.62585] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 03/06/2021] [Indexed: 01/10/2023] Open
Abstract
Little is known about the molecular changes that take place in the kidney during the aging process. In order to better understand these changes, we measured mRNA and protein levels in genetically diverse mice at different ages. We observed distinctive change in mRNA and protein levels as a function of age. Changes in both mRNA and protein are associated with increased immune infiltration and decreases in mitochondrial function. Proteins show a greater extent of change and reveal changes in a wide array of biological processes including unique, organ-specific features of aging in kidney. Most importantly, we observed functionally important age-related changes in protein that occur in the absence of corresponding changes in mRNA. Our findings suggest that mRNA profiling alone provides an incomplete picture of molecular aging in the kidney and that examination of changes in proteins is essential to understand aging processes that are not transcriptionally regulated.
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Affiliation(s)
| | - Joel M Chick
- Harvard Medical SchoolBostonUnited States
- VividionTherapeuticsSan DiegoUnited States
| | | | | | - Olivier Devuyst
- Institute of Physiology, University of ZurichZurichSwitzerland
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Ranjit S, Lanzanò L, Libby AE, Gratton E, Levi M. Advances in fluorescence microscopy techniques to study kidney function. Nat Rev Nephrol 2020; 17:128-144. [PMID: 32948857 DOI: 10.1038/s41581-020-00337-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2020] [Indexed: 02/07/2023]
Abstract
Fluorescence microscopy, in particular immunofluorescence microscopy, has been used extensively for the assessment of kidney function and pathology for both research and diagnostic purposes. The development of confocal microscopy in the 1950s enabled imaging of live cells and intravital imaging of the kidney; however, confocal microscopy is limited by its maximal spatial resolution and depth. More recent advances in fluorescence microscopy techniques have enabled increasingly detailed assessment of kidney structure and provided extraordinary insights into kidney function. For example, nanoscale precise imaging by rapid beam oscillation (nSPIRO) is a super-resolution microscopy technique that was originally developed for functional imaging of kidney microvilli and enables detection of dynamic physiological events in the kidney. A variety of techniques such as fluorescence recovery after photobleaching (FRAP), fluorescence correlation spectroscopy (FCS) and Förster resonance energy transfer (FRET) enable assessment of interaction between proteins. The emergence of other super-resolution techniques, including super-resolution stimulated emission depletion (STED), photoactivated localization microscopy (PALM), stochastic optical reconstruction microscopy (STORM) and structured illumination microscopy (SIM), has enabled functional imaging of cellular and subcellular organelles at ≤50 nm resolution. The deep imaging via emission recovery (DIVER) detector allows deep, label-free and high-sensitivity imaging of second harmonics, enabling assessment of processes such as fibrosis, whereas fluorescence lifetime imaging microscopy (FLIM) enables assessment of metabolic processes.
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Affiliation(s)
- Suman Ranjit
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC, USA. .,Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, USA.
| | - Luca Lanzanò
- Nanoscopy and NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy.,Department of Physics and Astronomy "Ettore Majorana", University of Catania, Catania, Italy
| | - Andrew E Libby
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC, USA
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, USA.
| | - Moshe Levi
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC, USA.
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13
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Abstract
Phosphate is an essential nutrient for life and is a critical component of bone formation, a major signaling molecule, and structural component of cell walls. Phosphate is also a component of high-energy compounds (i.e., AMP, ADP, and ATP) and essential for nucleic acid helical structure (i.e., RNA and DNA). Phosphate plays a central role in the process of mineralization, normal serum levels being associated with appropriate bone mineralization, while high and low serum levels are associated with soft tissue calcification. The serum concentration of phosphate and the total body content of phosphate are highly regulated, a process that is accomplished by the coordinated effort of two families of sodium-dependent transporter proteins. The three isoforms of the SLC34 family (SLC34A1-A3) show very restricted tissue expression and regulate intestinal absorption and renal excretion of phosphate. SLC34A2 also regulates the phosphate concentration in multiple lumen fluids including milk, saliva, pancreatic fluid, and surfactant. Both isoforms of the SLC20 family exhibit ubiquitous expression (with some variation as to which one or both are expressed), are regulated by ambient phosphate, and likely serve the phosphate needs of the individual cell. These proteins exhibit similarities to phosphate transporters in nonmammalian organisms. The proteins are nonredundant as mutations in each yield unique clinical presentations. Further research is essential to understand the function, regulation, and coordination of the various phosphate transporters, both the ones described in this review and the phosphate transporters involved in intracellular transport.
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Affiliation(s)
- Nati Hernando
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Kenneth Gagnon
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Eleanor Lederer
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
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14
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Abstract
Over the past 25 years, successive cloning of SLC34A1, SLC34A2 and SLC34A3, which encode the sodium-dependent inorganic phosphate (Pi) cotransport proteins 2a-2c, has facilitated the identification of molecular mechanisms that underlie the regulation of renal and intestinal Pi transport. Pi and various hormones, including parathyroid hormone and phosphatonins, such as fibroblast growth factor 23, regulate the activity of these Pi transporters through transcriptional, translational and post-translational mechanisms involving interactions with PDZ domain-containing proteins, lipid microdomains and acute trafficking of the transporters via endocytosis and exocytosis. In humans and rodents, mutations in any of the three transporters lead to dysregulation of epithelial Pi transport with effects on serum Pi levels and can cause cardiovascular and musculoskeletal damage, illustrating the importance of these transporters in the maintenance of local and systemic Pi homeostasis. Functional and structural studies have provided insights into the mechanism by which these proteins transport Pi, whereas in vivo and ex vivo cell culture studies have identified several small molecules that can modify their transport function. These small molecules represent potential new drugs to help maintain Pi homeostasis in patients with chronic kidney disease - a condition that is associated with hyperphosphataemia and severe cardiovascular and skeletal consequences.
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15
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Oneto M, Scipioni L, Sarmento MJ, Cainero I, Pelicci S, Furia L, Pelicci PG, Dellino GI, Bianchini P, Faretta M, Gratton E, Diaspro A, Lanzanò L. Nanoscale Distribution of Nuclear Sites by Super-Resolved Image Cross-Correlation Spectroscopy. Biophys J 2019; 117:2054-2065. [PMID: 31732142 PMCID: PMC6895719 DOI: 10.1016/j.bpj.2019.10.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/21/2019] [Accepted: 10/29/2019] [Indexed: 02/07/2023] Open
Abstract
Deciphering the spatiotemporal coordination between nuclear functions is important to understand its role in the maintenance of human genome. In this context, super-resolution microscopy has gained considerable interest because it can be used to probe the spatial organization of functional sites in intact single-cell nuclei in the 20-250 nm range. Among the methods that quantify colocalization from multicolor images, image cross-correlation spectroscopy (ICCS) offers several advantages, namely it does not require a presegmentation of the image into objects and can be used to detect dynamic interactions. However, the combination of ICCS with super-resolution microscopy has not been explored yet. Here, we combine dual-color stimulated emission depletion (STED) nanoscopy with ICCS (STED-ICCS) to quantify the nanoscale distribution of functional nuclear sites. We show that super-resolved ICCS provides not only a value of the colocalized fraction but also the characteristic distances associated to correlated nuclear sites. As a validation, we quantify the nanoscale spatial distribution of three different pairs of functional nuclear sites in MCF10A cells. As expected, transcription foci and a transcriptionally repressive histone marker (H3K9me3) are not correlated. Conversely, nascent DNA replication foci and the proliferating cell nuclear antigen(PCNA) protein have a high level of proximity and are correlated at a nanometer distance scale that is close to the limit of our experimental approach. Finally, transcription foci are found at a distance of 130 nm from replication foci, indicating a spatial segregation at the nanoscale. Overall, our data demonstrate that STED-ICCS can be a powerful tool for the analysis of the nanoscale distribution of functional sites in the nucleus.
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Affiliation(s)
- Michele Oneto
- Nanoscopy and NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Lorenzo Scipioni
- Nanoscopy and NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy; Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California
| | - Maria J Sarmento
- Nanoscopy and NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Isotta Cainero
- Nanoscopy and NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy; Department of Physics, University of Genoa, Genoa, Italy
| | - Simone Pelicci
- Nanoscopy and NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy; Department of Physics, University of Genoa, Genoa, Italy
| | - Laura Furia
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, Milan, Italy
| | - Pier G Pelicci
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, Milan, Italy; Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy
| | - Gaetano I Dellino
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, Milan, Italy; Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy
| | - Paolo Bianchini
- Nanoscopy and NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Mario Faretta
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, Milan, Italy
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, California
| | - Alberto Diaspro
- Nanoscopy and NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy; Department of Physics, University of Genoa, Genoa, Italy.
| | - Luca Lanzanò
- Nanoscopy and NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy.
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Pelicci S, Diaspro A, Lanzanò L. Chromatin nanoscale compaction in live cells visualized by acceptor-to-donor ratio corrected Förster resonance energy transfer between DNA dyes. JOURNAL OF BIOPHOTONICS 2019; 12:e201900164. [PMID: 31365191 PMCID: PMC7065635 DOI: 10.1002/jbio.201900164] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 07/14/2019] [Accepted: 07/29/2019] [Indexed: 05/04/2023]
Abstract
@Chromatin nanoscale architecture in live cells can be studied by Förster resonance energy transfer (FRET) between fluorescently labeled chromatin components, such as histones. A higher degree of nanoscale compaction is detected as a higher FRET level, since this corresponds to a higher degree of proximity between donor and acceptor molecules. However, in such a system, the stoichiometry of the donors and acceptors engaged in the FRET process is not well defined and, in principle, FRET variations could be caused by variations in the acceptor-to-donor ratio rather than distance. Here, to get a FRET level independent of the acceptor-to-donor ratio, we combine fluorescence lifetime imaging detection of FRET with a normalization of the FRET level to a pixel-wise estimation of the acceptor-to-donor ratio. We use this method to study FRET between two DNA binding dyes staining the nuclei of live cells. We show that this acceptor-to-donor ratio corrected FRET imaging reveals variations of nanoscale compaction in different chromatin environments. As an application, we monitor the rearrangement of chromatin in response to laser-induced microirradiation and reveal that DNA is rapidly decompacted, at the nanoscale, in response to DNA damage induction.
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Affiliation(s)
- Simone Pelicci
- Nanoscopy and Nikon Imaging Center, Istituto Italiano di TecnologiaGenoaItaly
- Department of PhysicsUniversity of GenoaGenoaItaly
| | - Alberto Diaspro
- Nanoscopy and Nikon Imaging Center, Istituto Italiano di TecnologiaGenoaItaly
- Department of PhysicsUniversity of GenoaGenoaItaly
| | - Luca Lanzanò
- Nanoscopy and Nikon Imaging Center, Istituto Italiano di TecnologiaGenoaItaly
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17
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Levi M, Gratton E. Visualizing the regulation of SLC34 proteins at the apical membrane. Pflugers Arch 2019; 471:533-542. [PMID: 30613865 PMCID: PMC6436987 DOI: 10.1007/s00424-018-02249-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 10/27/2022]
Abstract
The cloning of the renal NaPi-2a (SLC34A1) and NaPi-2c (SLC34A3) phosphate transporters has made it possible to characterize the molecular and biophysical regulation of renal proximal tubular reabsorption of inorganic phosphate (Pi). Dietary factors, such as Pi and K, and several hormones and phosphatonins, including parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and glucocorticoids, regulate the transporters through various transcriptional, translational, and post-translational mechanisms that involve acute trafficking via endocytosis or exocytosis, interactions with PDZ domain proteins, lipid microdomains, and diffusion and clustering in the apical brush border membrane. The visualization of these trafficking events by means of novel microscopy techniques that includes fluorescence lifetime imaging microscopy (FLIM), Förster resonance energy transfer (FRET), fluctuation correlation spectroscopy (FCS), and modulation tracking (MT), is the primary focus of this review.
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Affiliation(s)
- Moshe Levi
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University, Washington, DC, USA.
| | - Enrico Gratton
- Department of Biomedical Engineering, Laboratory for Fluorescence Dynamics, University of California at Irvine, Irvine, CA, USA
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18
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Ferreira C, Hagen P, Stern M, Hussner J, Zimmermann U, Grube M, Meyer zu Schwabedissen HE. The scaffold protein PDZK1 modulates expression and function of the organic anion transporting polypeptide 2B1. Eur J Pharm Sci 2018; 120:181-190. [DOI: 10.1016/j.ejps.2018.05.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 05/08/2018] [Indexed: 11/25/2022]
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19
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Bergsland KJ, Coe FL, Parks JH, Asplin JR, Worcester EM. Evidence for a role of PDZ domain-containing proteins to mediate hypophosphatemia in calcium stone formers. Nephrol Dial Transplant 2018; 33:759-770. [PMID: 29126251 DOI: 10.1093/ndt/gfx284] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 08/29/2017] [Indexed: 01/26/2023] Open
Abstract
Background Hypophosphatemia (HYP) is common among calcium stone formers (SFs) and in rare cases is associated with mutations in sodium-phosphate cotransporters or in Na+/H+ exchanger regulatory factor 1 (NHERF1), but the majority of cases are unexplained. We hypothesized that reduced sodium-phosphate cotransporter activity mediated via NHERF1 or a similar PDZ domain-containing protein, causes HYP. If so, other transport activities controlled by NHERF1, such as NHE3 and URAT1, might be reduced in HYP. Methods To test this idea, we analyzed two large but separate sets of 24-h urine samples and paired serums of 2700 SFs from the University of Chicago and 11 073 SFs from Litholink, a national laboratory. Patients were divided into quintiles based on serum phosphate. Results Males were more common in the lowest phosphate tiles in both datasets. Phosphate excretion did not vary across the quintiles, excluding diet as a cause of HYP. Tubule maximum (Tm) phosphate per unit glomerular filtration rate decreased and fractional excretion increased with decreasing phosphate quintiles, indicating reduced tubule phosphate reabsorption was responsible for HYP. Urine pH and serum chloride increased with decreasing serum phosphate, suggesting a coordinate change in NHE3 activity. Serum uric acid and Tm uric acid decreased significantly with decreasing serum phosphate, while uric acid excretion did not vary. Conclusion. HYP in SFs results from decreased tubule phosphate reabsorption and, being associated with related changes in other proximal tubule transporters, may arise from alterations in or signaling to PDZ-containing proteins.
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Affiliation(s)
| | - Fredric L Coe
- Department of Medicine, University of Chicago, Chicago, IL, USA
| | - Joan H Parks
- Department of Medicine, University of Chicago, Chicago, IL, USA
| | - John R Asplin
- Litholink Corporation, Laboratory Corporation of America Holdings, Chicago, IL, USA
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20
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Scipioni L, Gratton E, Diaspro A, Lanzanò L. Phasor Analysis of Local ICS Detects Heterogeneity in Size and Number of Intracellular Vesicles. Biophys J 2017; 111:619-629. [PMID: 27508445 PMCID: PMC4982927 DOI: 10.1016/j.bpj.2016.06.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 06/09/2016] [Accepted: 06/22/2016] [Indexed: 01/28/2023] Open
Abstract
Organelles represent the scale of organization immediately below that of the cell itself, and their composition, size, and number are tailored to their function. Monitoring the size and number of organelles in live cells is relevant for many applications but can be challenging due to their highly heterogeneous properties. Image correlation spectroscopy is a well-established analysis method capable of extracting the average size and number of particles in images. However, when image correlation spectroscopy is applied to a highly heterogeneous system, it can fail to retrieve, from a single correlation function, the characteristic size and the relative amount associated to each subspecies. Here, we describe a fast, unbiased, and fit-free algorithm based on the phasor analysis of multiple local image correlation functions, capable of mapping the sizes of elements contained in a heterogeneous system. The method correctly provides the size and number of separate subspecies, which otherwise would be hidden in the average properties of a single correlation function. We apply the method to quantify the spatial and temporal heterogeneity in the size and number of intracellular vesicles formed after endocytosis in live cells.
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Affiliation(s)
- Lorenzo Scipioni
- Nanoscopy, Nanophysics, Istituto Italiano di Tecnologia, Genoa, Italy; Department of Computer Science, Bioengineering, Robotics and Systems Engineering, University of Genoa, Genoa, Italy
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, Irvine, California
| | - Alberto Diaspro
- Nanoscopy, Nanophysics, Istituto Italiano di Tecnologia, Genoa, Italy; Nikon Imaging Center, Istituto Italiano di Tecnologia, Genoa, Italy; Department of Physics, University of Genoa, Genoa, Italy
| | - Luca Lanzanò
- Nanoscopy, Nanophysics, Istituto Italiano di Tecnologia, Genoa, Italy.
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Fenton RA, Poulsen SB, de la Mora Chavez S, Soleimani M, Dominguez Rieg JA, Rieg T. Renal tubular NHE3 is required in the maintenance of water and sodium chloride homeostasis. Kidney Int 2017; 92:397-414. [PMID: 28385297 DOI: 10.1016/j.kint.2017.02.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 01/25/2017] [Accepted: 02/02/2017] [Indexed: 11/30/2022]
Abstract
The sodium/proton exchanger isoform 3 (NHE3) is expressed in the intestine and the kidney, where it facilitates sodium (re)absorption and proton secretion. The importance of NHE3 in the kidney for sodium chloride homeostasis, relative to the intestine, is unknown. Constitutive tubule-specific NHE3 knockout mice (NHE3loxloxCre) did not show significant differences compared to control mice in body weight, blood pH or bicarbonate and plasma sodium, potassium, or aldosterone levels. Fluid intake, urinary flow rate, urinary sodium/creatinine, and pH were significantly elevated in NHE3loxloxCre mice, while urine osmolality and GFR were significantly lower. Water deprivation revealed a small urinary concentrating defect in NHE3loxloxCre mice on a control diet, exaggerated on low sodium chloride. Ten days of low or high sodium chloride diet did not affect plasma sodium in control mice; however, NHE3loxloxCre mice were susceptible to low sodium chloride (about -4 mM) or high sodium chloride intake (about +2 mM) versus baseline, effects without differences in plasma aldosterone between groups. Blood pressure was significantly lower in NHE3loxloxCre mice and was sodium chloride sensitive. In control mice, the expression of the sodium/phosphate co-transporter Npt2c was sodium chloride sensitive. However, lack of tubular NHE3 blunted Npt2c expression. Alterations in the abundances of sodium/chloride cotransporter and its phosphorylation at threonine 58 as well as the abundances of the α-subunit of the epithelial sodium channel, and its cleaved form, were also apparent in NHE3loxloxCre mice. Thus, renal NHE3 is required to maintain blood pressure and steady-state plasma sodium levels when dietary sodium chloride intake is modified.
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Affiliation(s)
- Robert A Fenton
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Søren B Poulsen
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark; VA San Diego Healthcare System, San Diego, California, USA
| | | | - Manoocher Soleimani
- Department of Medicine, University of Cincinnati, Cincinnati, Ohio, USA; Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio, USA
| | - Jessica A Dominguez Rieg
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida, USA
| | - Timo Rieg
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida, USA.
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Venot Q, Delaunay JL, Fouassier L, Delautier D, Falguières T, Housset C, Maurice M, Aït-Slimane T. A PDZ-Like Motif in the Biliary Transporter ABCB4 Interacts with the Scaffold Protein EBP50 and Regulates ABCB4 Cell Surface Expression. PLoS One 2016; 11:e0146962. [PMID: 26789121 PMCID: PMC4720445 DOI: 10.1371/journal.pone.0146962] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 12/23/2015] [Indexed: 12/11/2022] Open
Abstract
ABCB4/MDR3, a member of the ABC superfamily, is an ATP-dependent phosphatidylcholine translocator expressed at the canalicular membrane of hepatocytes. Defects in the ABCB4 gene are associated with rare biliary diseases. It is essential to understand the mechanisms of its canalicular membrane expression in particular for the development of new therapies. The stability of several ABC transporters is regulated through their binding to PDZ (PSD95/DglA/ZO-1) domain-containing proteins. ABCB4 protein ends by the sequence glutamine-asparagine-leucine (QNL), which shows some similarity to PDZ-binding motifs. The aim of our study was to assess the potential role of the QNL motif on the surface expression of ABCB4 and to determine if PDZ domain-containing proteins are involved. We found that truncation of the QNL motif decreased the stability of ABCB4 in HepG2-transfected cells. The deleted mutant ABCB4-ΔQNL also displayed accelerated endocytosis. EBP50, a PDZ protein highly expressed in the liver, strongly colocalized and coimmunoprecipitated with ABCB4, and this interaction required the QNL motif. Down-regulation of EBP50 by siRNA or by expression of an EBP50 dominant-negative mutant caused a significant decrease in the level of ABCB4 protein expression, and in the amount of ABCB4 localized at the canalicular membrane. Interaction of ABCB4 with EBP50 through its PDZ-like motif plays a critical role in the regulation of ABCB4 expression and stability at the canalicular plasma membrane.
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Affiliation(s)
- Quitterie Venot
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Jean-Louis Delaunay
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Laura Fouassier
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Danièle Delautier
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Thomas Falguières
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Chantal Housset
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Antoine, Centre de Référence Maladies Rares Maladies Inflammatoires des Voies Biliaires & Service d’Hépatologie, Paris, France
| | - Michèle Maurice
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
| | - Tounsia Aït-Slimane
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France
- * E-mail:
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Tatsumi S, Miyagawa A, Kaneko I, Shiozaki Y, Segawa H, Miyamoto KI. Regulation of renal phosphate handling: inter-organ communication in health and disease. J Bone Miner Metab 2016; 34:1-10. [PMID: 26296817 DOI: 10.1007/s00774-015-0705-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 07/16/2015] [Indexed: 01/18/2023]
Abstract
In this review, we focus on the interconnection of inorganic phosphate (Pi) homeostasis in the network of the bone-kidney, parathyroid-kidney, intestine-kidney, and liver-kidney axes. Such a network of organ communication is important for body Pi homeostasis. Normalization of serum Pi levels is a clinical target in patients with chronic kidney disease (CKD). Particularly, disorders of the fibroblast growth factor 23/klotho system are observed in early CKD. Identification of phosphaturic factors from the intestine and liver may enhance our understanding of body Pi homeostasis and Pi metabolism disturbances in CKD patients.
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Affiliation(s)
- Sawako Tatsumi
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Atsumi Miyagawa
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Ichiro Kaneko
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Yuji Shiozaki
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Hiroko Segawa
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Ken-Ichi Miyamoto
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan.
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Walsh DR, Nolin TD, Friedman PA. Drug Transporters and Na+/H+ Exchange Regulatory Factor PSD-95/Drosophila Discs Large/ZO-1 Proteins. Pharmacol Rev 2015; 67:656-80. [PMID: 26092975 PMCID: PMC4485015 DOI: 10.1124/pr.115.010728] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Drug transporters govern the absorption, distribution, and elimination of pharmacologically active compounds. Members of the solute carrier and ATP binding-cassette drug transporter family mediate cellular drug uptake and efflux processes, thereby coordinating the vectorial movement of drugs across epithelial barriers. To exert their physiologic and pharmacological function in polarized epithelia, drug transporters must be targeted and stabilized to appropriate regions of the cell membrane (i.e., apical versus basolateral). Despite the critical importance of drug transporter membrane targeting, the mechanisms that underlie these processes are largely unknown. Several clinically significant drug transporters possess a recognition sequence that binds to PSD-95/Drosophila discs large/ZO-1 (PDZ) proteins. PDZ proteins, such as the Na(+)/H(+) exchanger regulatory factor (NHERF) family, act to stabilize and organize membrane targeting of multiple transmembrane proteins, including many clinically relevant drug transporters. These PDZ proteins are normally abundant at apical membranes, where they tether membrane-delimited transporters. NHERF expression is particularly high at the apical membrane in polarized tissue such as intestinal, hepatic, and renal epithelia, tissues important to drug disposition. Several recent studies have highlighted NHERF proteins as determinants of drug transporter function secondary to their role in controlling membrane abundance and localization. Mounting evidence strongly suggests that NHERF proteins may have clinically significant roles in pharmacokinetics and pharmacodynamics of several pharmacologically active compounds and may affect drug action in cancer and chronic kidney disease. For these reasons, NHERF proteins represent a novel class of post-translational mediators of drug transport and novel targets for new drug development.
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Affiliation(s)
- Dustin R Walsh
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, and Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania (P.A.F.); and Center for Clinical Pharmaceutical Sciences, Department of Pharmacy and Therapeutics, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania (D.R.W., T.D.N.)
| | - Thomas D Nolin
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, and Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania (P.A.F.); and Center for Clinical Pharmaceutical Sciences, Department of Pharmacy and Therapeutics, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania (D.R.W., T.D.N.)
| | - Peter A Friedman
- Laboratory for G Protein-Coupled Receptor Biology, Department of Pharmacology and Chemical Biology, and Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania (P.A.F.); and Center for Clinical Pharmaceutical Sciences, Department of Pharmacy and Therapeutics, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania (D.R.W., T.D.N.)
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Fenton RA, Poulsen SB, de la Mora Chavez S, Soleimani M, Busslinger M, Dominguez Rieg JA, Rieg T. Caffeine-induced diuresis and natriuresis is independent of renal tubular NHE3. Am J Physiol Renal Physiol 2015; 308:F1409-20. [PMID: 25925253 DOI: 10.1152/ajprenal.00129.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 04/18/2015] [Indexed: 01/15/2023] Open
Abstract
Caffeine is one of the most widely consumed behavioral substances. We have previously shown that caffeine- and theophylline-induced inhibition of renal reabsorption causes diuresis and natriuresis, an effect that requires functional adenosine A1 receptors. In this study, we tested the hypothesis that blocking the Gi protein-coupled adenosine A1 receptor via the nonselective adenosine receptor antagonist caffeine changes Na(+)/H(+) exchanger isoform 3 (NHE3) localization and phosphorylation, resulting in diuresis and natriuresis. We generated tubulus-specific NHE3 knockout mice (Pax8-Cre), where NHE3 abundance in the S1, S2, and S3 segments of the proximal tubule was completely absent or severely reduced (>85%) in the thick ascending limb. Consumption of fluid and food, as well as glomerular filtration rate, were comparable in control or tubulus-specific NHE3 knockout mice under basal conditions, while urinary pH was significantly more alkaline without evidence for metabolic acidosis. Caffeine self-administration increased total fluid and food intake comparably between genotypes, without significant differences in consumption of caffeinated solution. Acute caffeine application via oral gavage elicited a diuresis and natriuresis that was comparable between control and tubulus-specific NHE3 knockout mice. The diuretic and natriuretic response was independent of changes in total NHE3 expression, phosphorylation of serine-552 and serine-605, or apical plasma membrane NHE3 localization. Although caffeine had no clear effect on localization of the basolateral Na(+)/bicarbonate cotransporter NBCe1, pretreatment with DIDS inhibited caffeine-induced diuresis and natriuresis. In summary, NHE3 is not required for caffeine-induced diuresis and natriuresis.
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Affiliation(s)
- Robert A Fenton
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Søren B Poulsen
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Manoocher Soleimani
- Department of Medicine, University of Cincinnati, Cincinnati, Ohio; Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio
| | | | - Jessica A Dominguez Rieg
- VA San Diego Healthcare System, San Diego, California; Bastyr University California, San Diego, California; and
| | - Timo Rieg
- VA San Diego Healthcare System, San Diego, California; Department of Medicine, University of California, San Diego, La Jolla, California
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Fenton RA, Murray F, Dominguez Rieg JA, Tang T, Levi M, Rieg T. Renal phosphate wasting in the absence of adenylyl cyclase 6. J Am Soc Nephrol 2014; 25:2822-34. [PMID: 24854272 PMCID: PMC4243352 DOI: 10.1681/asn.2013101102] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 03/31/2014] [Indexed: 11/03/2022] Open
Abstract
Parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF-23) enhance phosphate excretion by the proximal tubule of the kidney by retrieval of the sodium-dependent phosphate transporters (Npt2a and Npt2c) from the apical plasma membrane. PTH activates adenylyl cyclase (AC) through PTH 1 receptors and stimulates the cAMP/PKA signaling pathway. However, the precise role and isoform(s) of AC in phosphate homeostasis are not known. We report here that mice lacking AC6 (AC6(-/-)) have increased plasma PTH and FGF-23 levels compared with wild-type (WT) mice but comparable plasma phosphate concentrations. Acute activation of the calcium-sensing receptor or feeding a zero phosphate diet almost completely suppressed plasma PTH levels in both AC6(-/-) and WT mice, indicating a secondary cause for hyperparathyroidism. Pharmacologic blockade of FGF receptors resulted in a comparable increase in plasma phosphate between genotypes, whereas urinary phosphate remained significantly higher in AC6(-/-) mice. Compared with WT mice, AC6(-/-) mice had reduced renal Npt2a and Npt2c protein abundance, with approximately 80% of Npt2a residing in lysosomes. WT mice responded to exogenous PTH with redistribution of Npt2a from proximal tubule microvilli to intracellular compartments and lysosomes alongside a PTH-induced dose-response relationship for fractional phosphate excretion and urinary cAMP excretion. These responses were absent in AC6(-/-) mice. In conclusion, AC6 in the proximal tubule modulates cAMP formation, Npt2a trafficking, and urinary phosphate excretion, which are highlighted by renal phosphate wasting in AC6(-/-) mice.
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Affiliation(s)
- Robert A Fenton
- Interactions of Proteins in Epithelial Transport Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Fiona Murray
- Department of Medicine, University of California San Diego, La Jolla, California
| | | | - Tong Tang
- Veterans Affairs San Diego Healthcare System, San Diego, California; and
| | - Moshe Levi
- Department of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Timo Rieg
- Department of Medicine, University of California San Diego, La Jolla, California; Veterans Affairs San Diego Healthcare System, San Diego, California; and
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Lanzanò L, Gratton E. Orbital Single Particle Tracking on a commercial confocal microscope using piezoelectric stage feedback. Methods Appl Fluoresc 2014; 2. [PMID: 25419461 DOI: 10.1088/2050-6120/2/2/024010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Single Particle Tracking (SPT) is a technique used to locate fluorescent particles with nanometer precision. In the orbital tracking method the position of a particle is obtained analyzing the distribution of intensity along a circular orbit scanned around the particle. In combination with an active feedback this method allows tracking of particles in 2D and 3D with millisecond temporal resolution. Here we describe a SPT setup based on a feedback approach implemented with minimal modification of a commercially available confocal laser scanning microscope, the Zeiss LSM 510, in combination with an external piezoelectric stage scanner. The commercial microscope offers the advantage of a user-friendly software interface and pre-calibrated hardware components. The use of an external piezo-scanner allows the addition of feedback into the system but also represents a limitation in terms of its mechanical response. We describe in detail this implementation of the orbital tracking method and discuss advantages and limitations. As an example of application to live cell experiments we perform the 3D tracking of acidic vesicles in live polarized epithelial cells.
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Affiliation(s)
- Luca Lanzanò
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA 92697, United States
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA 92697, United States
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28
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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: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Park J, Kwak JO, Riederer B, Seidler U, Cole SPC, Lee HJ, Lee MG. Na⁺/H⁺ exchanger regulatory factor 3 is critical for multidrug resistance protein 4-mediated drug efflux in the kidney. J Am Soc Nephrol 2014; 25:726-36. [PMID: 24436471 DOI: 10.1681/asn.2013040438] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Na(+)/H(+) exchanger regulatory factor 3 (NHERF3) is a PSD-95/discs large/ZO-1 (PDZ)-based adaptor protein that regulates several membrane-transporting proteins in epithelia. However, the in vivo physiologic role of NHERF3 in transepithelial transport remains poorly understood. Multidrug resistance protein 4 (MRP4) is an ATP binding cassette transporter that mediates the efflux of organic molecules, such as nucleoside analogs, in the gastrointestinal and renal epithelia. Here, we report that Nherf3 knockout (Nherf3(-/-)) mice exhibit profound reductions in Mrp4 expression and Mrp4-mediated drug transport in the kidney. A search for the binding partners of the COOH-terminal PDZ binding motif of MRP4 among several epithelial PDZ proteins indicated that MRP4 associated most strongly with NHERF3. When expressed in HEK293 cells, NHERF3 increased membrane expression of MRP4 by reducing internalization of cell surface MRP4 and consequently, augmented MRP4-mediated efflux of adefovir, a nucleoside-based antiviral agent and well known substrate of MRP4. Examination of wild-type and Nherf3(-/-) mice revealed that Nherf3 is most abundantly expressed in the kidney and has a prominent role in modulating Mrp4 levels. Deletion of Nherf3 in mice caused a profound reduction in Mrp4 expression at the apical membrane of renal proximal tubules and evoked a significant increase in the plasma and kidney concentrations of adefovir, with a corresponding decrease in the systemic clearance of this drug. These results suggest that NHERF3 is a key regulator of organic transport in the kidney, particularly MRP4-mediated clearance of drug molecules.
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Affiliation(s)
- Joonhee Park
- Department of Pharmacology and Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
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30
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Cutrale F, Salih A, Gratton E. Spectral Phasor approach for fingerprinting of photo-activatable fluorescent proteins Dronpa, Kaede and KikGR. Methods Appl Fluoresc 2013; 1:035001. [PMID: 24040513 DOI: 10.1088/2050-6120/1/3/035001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The phasor global analysis algorithm is common for fluorescence lifetime applications, but has only been recently proposed for spectral analysis. Here the phasor representation and fingerprinting is exploited in its second harmonic to determine the number and spectra of photo-activated states as well as their conversion dynamics. We follow the sequence of photo-activation of proteins over time by rapidly collecting multiple spectral images. The phasor representation of the cumulative images provides easy identification of the spectral signatures of each photo-activatable protein.
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31
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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; , ,
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Dobrinskikh E, Lanzano L, Rachelson J, Cranston D, Moldovan R, Lei T, Gratton E, Doctor RB. Shank2 contributes to the apical retention and intracellular redistribution of NaPiIIa in OK cells. Am J Physiol Cell Physiol 2013; 304:C561-73. [PMID: 23325414 DOI: 10.1152/ajpcell.00189.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In renal proximal tubule (PT) cells, sodium-phosphate cotransporter IIa (NaPiIIa) is normally concentrated within the apical membrane where it reabsorbs ∼70% of luminal phosphate (Pi). NaPiIIa activity is acutely regulated by moderating its abundance within the apical membrane. Under low-Pi conditions, NaPiIIa is retained within the apical membrane. Under high-Pi conditions, NaPiIIa is retrieved from the apical membrane and trafficked to the lysosomes for degradation. The present study investigates the role of Shank2 in regulating the distribution of NaPiIIa. In opossum kidney cells, a PT cell model, knockdown of Shank2 in cells maintained in low-Pi media resulted in a marked decrease in NaPiIIa abundance. After being transferred into high-Pi media, live-cell imaging showed that mRFP-Shank2E and GFP-NaPiIIa underwent endocytosis and trafficked together through the subapical domain. Fluorescence cross-correlation spectroscopy demonstrated that GFP-NaPiIIa and mRFP-Shank2 have indistinguishable diffusion coefficients and migrated through the subapical domain in temporal synchrony. Raster image cross-correlation spectroscopy demonstrated these two proteins course through the subapical domain in temporal-spatial synchrony. In the microvilli of cells under low-Pi conditions and in the subapical domain of cells under high-Pi conditions, fluorescence lifetime imaging microscopy-Forster resonance energy transfer analysis of Cer-NaPiIIa and EYFP-Shank2E found these fluors reside within 10 nm of each other. Demonstrating a complexity of functions, in cells maintained under low-Pi conditions, Shank2 plays an essential role in the apical retention of NaPiIIa while under high-Pi conditions Shank2 remains associated with NaPiIIa and escorts NaPiIIa through the cell interior.
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Affiliation(s)
- Evgenia Dobrinskikh
- Department of Medicine, University of Colorado, Denver, 12700 E. 19th Ave., RC2 10121, Aurora, CO 80045, USA
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33
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Giral H, Cranston D, Lanzano L, Caldas Y, Sutherland E, Rachelson J, Dobrinskikh E, Weinman EJ, Doctor RB, Gratton E, Levi M. NHE3 regulatory factor 1 (NHERF1) modulates intestinal sodium-dependent phosphate transporter (NaPi-2b) expression in apical microvilli. J Biol Chem 2012; 287:35047-35056. [PMID: 22904329 DOI: 10.1074/jbc.m112.392415] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
P(i) uptake in the small intestine occurs predominantly through the NaPi-2b (SLC34a2) co-transporter. NaPi-2b is regulated by changes in dietary P(i) but the mechanisms underlying this regulation are largely undetermined. Sequence analyses show NaPi-2b has a PDZ binding motif at its C terminus. Immunofluorescence imaging shows NaPi-2b and two PDZ domain containing proteins, NHERF1 and PDZK1, are expressed in the apical microvillar domain of rat small intestine enterocytes. Co-immunoprecipitation studies in rat enterocytes show that NHERF1 associates with NaPi-2b but not PDZK1. In HEK co-expression studies, GFP-NaPi-2b co-precipitates with FLAG-NHERF1. This interaction is markedly diminished when the C-terminal four amino acids are truncated from NaPi-2b. FLIM-FRET analyses using tagged proteins in CACO-2(BBE) cells show a distinct phasor shift between NaPi-2b and NHERF1 but not between NaPi-2b and the PDZK1 pair. This shift demonstrates that NaPi-2b and NHERF1 reside within 10 nm of each other. NHERF1(-/-) mice, but not PDZK1(-/-) mice, had a diminished adaptation of NaPi-2b expression in response to a low P(i) diet. Together these studies demonstrate that NHERF1 associates with NaPi-2b in enterocytes and regulates NaPi-2b adaptation.
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Affiliation(s)
- Hector Giral
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - DeeAnn Cranston
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Luca Lanzano
- Department of Biomedical Engineering, Laboratory for Fluorescence Dynamics, University of California, Irvine, California 92697
| | - Yupanqui Caldas
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Eileen Sutherland
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Joanna Rachelson
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Evgenia Dobrinskikh
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Edward J Weinman
- Department of Medicine and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - R Brian Doctor
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Enrico Gratton
- Department of Biomedical Engineering, Laboratory for Fluorescence Dynamics, University of California, Irvine, California 92697
| | - Moshe Levi
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045.
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Yu Y, Sanderson S, Reyes M, Sharma A, Dunbar N, Srivastava T, Jüppner H, Bergwitz C. Novel NaPi-IIc mutations causing HHRH and idiopathic hypercalciuria in several unrelated families: long-term follow-up in one kindred. Bone 2012; 50:1100-6. [PMID: 22387237 PMCID: PMC3322249 DOI: 10.1016/j.bone.2012.02.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 02/09/2012] [Accepted: 02/15/2012] [Indexed: 02/06/2023]
Abstract
Homozygous and compound heterozygous mutations in SLC34A3, the gene encoding the sodium-dependent co-transporter NaPi-IIc, cause hereditary hypophosphatemic rickets with hypercalciuria (HHRH), a disorder characterized by renal phosphate-wasting resulting in hypophosphatemia, elevated 1,25(OH)(2) vitamin D levels, hypercalciuria, rickets/osteomalacia, and frequently kidney stones or nephrocalcinosis. Similar albeit less severe biochemical changes are also observed in heterozygous carriers, which are furthermore indistinguishable from those encountered in idiopathic hypercalciuria (IH). We now searched for SLC34A3 mutations (exons and introns) in two previously not reported HHRH kindreds, which resulted in the identification of three novel mutations. The affected members of kindred A were compound heterozygous for two different mutations, c.1046_47del and the intronic mutation c.560+23_561-42del, while the index case in kindred B was homozygous for the nonsense SLC34A3 mutation c.1764C>G (p.Y588X). The patient in kindred C was diagnosed with IH because of bilateral medullary nephrocalcinosis, suppressed PTH levels, and hypercalciuria; she was found to have a novel heterozygous c.1571_1880del mutation. The HHRH patients in kindred A were treated for up to 7years with oral phosphate, which led to reversal of hypophosphatemia, hypercalciuria, and prevention or healing of the mild bone abnormalities. PTH levels were normal throughout the observation period, while 1,25(OH)(2) vitamin D levels remained elevated and may thus be helpful for assessing treatment efficacy and patient compliance in HHRH.
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Affiliation(s)
- Y. Yu
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - S.R. Sanderson
- Pediatric Endocrinology, Horizon Health Network, Saint John, New Brunswick E2L 4L2, Canada
| | - M. Reyes
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - A. Sharma
- Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - N. Dunbar
- Pediatric Endocrinology, Baystate Medical Center, Springfield, MA 01199, USA
| | - T. Srivastava
- Bone and Mineral Disorder Clinic, Section of Pediatric Nephrology, The Children’s Mercy Hospital and Clinics, University of Missouri at Kansas City, Kansas City, MO 64108, USA
| | - H. Jüppner
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
- Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - C. Bergwitz
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
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Haito-Sugino S, Ito M, Ohi A, Shiozaki Y, Kangawa N, Nishiyama T, Aranami F, Sasaki S, Mori A, Kido S, Tatsumi S, Segawa H, Miyamoto KI. Processing and stability of type IIc sodium-dependent phosphate cotransporter mutations in patients with hereditary hypophosphatemic rickets with hypercalciuria. Am J Physiol Cell Physiol 2011; 302:C1316-30. [PMID: 22159077 DOI: 10.1152/ajpcell.00314.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mutations in the apically located Na(+)-dependent phosphate (NaPi) cotransporter, SLC34A3 (NaPi-IIc), are a cause of hereditary hypophosphatemic rickets with hypercalciuria (HHRH). We have characterized the impact of several HHRH mutations on the processing and stability of human NaPi-IIc. Mutations S138F, G196R, R468W, R564C, and c.228delC in human NaPi-IIc significantly decreased the levels of NaPi cotransport activities in Xenopus oocytes. In S138F and R564C mutant proteins, this reduction is a result of a decrease in the V(max) for P(i), but not the K(m). G196R, R468W, and c.228delC mutants were not localized to oocyte membranes. In opossum kidney (OK) cells, cell surface labeling, microscopic confocal imaging, and pulse-chase experiments showed that G196R and R468W mutations resulted in an absence of cell surface expression owing to endoplasmic reticulum (ER) retention. G196R and R468W mutants could be partially stabilized by low temperature. In blue native-polyacrylamide gel electrophoresis analysis, G196R and R468W mutants were either denatured or present in an aggregation complex. In contrast, S138F and R564C mutants were trafficked to the cell surface, but more rapidly degraded than WT protein. The c.228delC mutant did not affect endogenous NaPi uptake in OK cells. Thus, G196R and R468W mutations cause ER retention, while S138F and R564C mutations stimulate degradation of human NaPi-IIc in renal epithelial cells. Together, these data suggest that the NaPi-IIc mutants in HHRH show defective processing and stability.
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Affiliation(s)
- Sakiko Haito-Sugino
- Department of Molecular Nutrition, University of Tokushima Graduate School, Tokushima, Japan
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Ardura JA, Friedman PA. Regulation of G protein-coupled receptor function by Na+/H+ exchange regulatory factors. Pharmacol Rev 2011; 63:882-900. [PMID: 21873413 PMCID: PMC3186079 DOI: 10.1124/pr.110.004176] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Many G protein-coupled receptors (GPCR) exert patterns of cell-specific signaling and function. Mounting evidence now supports the view that cytoplasmic adapter proteins contribute critically to this behavior. Adapter proteins recognize highly conserved motifs such as those for Src homology 3 (SH3), phosphotyrosine-binding (PTB), and postsynaptic density 95/discs-large/zona occludens (PDZ) docking sequences in candidate GPCRs. Here we review the behavior of the Na+/H+ exchange regulatory factor (NHERF) family of PDZ adapter proteins on GPCR signalling, trafficking, and function. Structural determinants of NHERF proteins that allow them to recognize targeted GPCRs are considered. NHERF1 and NHERF2 are capable also of modifying the assembled complex of accessory proteins such as β-arrestins, which have been implicated in regulating GPCR signaling. In addition, NHERF1 and NHERF2 modulate GPCR signaling by altering the G protein to which the receptor binds or affect other regulatory proteins that affect GTPase activity, protein kinase A, phospholipase C, or modify downstream signaling events. Small molecules targeting the site of NHERF1-GPCR interaction are being developed and may become important and selective drug candidates.
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Affiliation(s)
- Juan A Ardura
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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37
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Lanzano L, Lei T, Okamura K, Giral H, Caldas Y, Masihzadeh O, Gratton E, Levi M, Blaine J. Differential modulation of the molecular dynamics of the type IIa and IIc sodium phosphate cotransporters by parathyroid hormone. Am J Physiol Cell Physiol 2011; 301:C850-61. [PMID: 21593452 DOI: 10.1152/ajpcell.00412.2010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The kidney is a key regulator of phosphate homeostasis. There are two predominant renal sodium phosphate cotransporters, NaPi2a and NaPi2c. Both are regulated by parathyroid hormone (PTH), which decreases the abundance of the NaPi cotransporters in the apical membrane of renal proximal tubule cells. The time course of PTH-induced removal of the two cotransporters from the apical membrane, however, is markedly different for NaPi2a compared with NaPi2c. In animals and in cell culture, PTH treatment results in almost complete removal of NaPi2a from the brush border (BB) within 1 h whereas for NaPi2c this process in not complete until 4 to 8 h after PTH treatment. The reason for this is poorly understood. We have previously shown that the unconventional myosin motor myosin VI is required for PTH-induced removal of NaPi2a from the proximal tubule BB. Here we demonstrate that myosin VI is also necessary for PTH-induced removal of NaPi2c from the apical membrane. In addition, we show that, while at baseline the two cotransporters have similar diffusion coefficients within the membrane, after PTH addition the diffusion coefficient for NaPi2a initially exceeds that for NaPi2c. Thus NaPi2c appears to remain "tethered" in the apical membrane for longer periods of time after PTH treatment, accounting, at least in part, for the difference in response times to PTH of NaPi2a versus NaPi2c.
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Affiliation(s)
- Luca Lanzano
- Laboratory for Fluorescence Dynamics, University of California, Irvine, USA
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