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Villanueva CE, Hagenbuch B. Palmitoylation of solute carriers. Biochem Pharmacol 2023; 215:115695. [PMID: 37481134 PMCID: PMC10530500 DOI: 10.1016/j.bcp.2023.115695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 07/05/2023] [Accepted: 07/12/2023] [Indexed: 07/24/2023]
Abstract
Post-translational modifications are an important mechanism in the regulation of protein expression, function, and degradation. Well-known post-translational modifications are phosphorylation, glycosylation, and ubiquitination. However, lipid modifications, including myristoylation, prenylation, and palmitoylation, are poorly studied. Since the early 2000s, researchers have become more interested in lipid modifications, especially palmitoylation. The number of articles in PubMed increased from about 350 between 2000 and 2005 to more than 600 annually during the past ten years. S-palmitoylation, where the 16-carbon saturated (C16:0) palmitic acid is added to free cysteine residues of proteins, is a reversible protein modification that can affect the expression, membrane localization, and function of the modified proteins. Various diseases like Huntington's and Alzheimer's disease have been linked to changes in protein palmitoylation. In humans, the addition of palmitic acid is mediated by 23 palmitoyl acyltransferases, also called DHHC proteins. The modification can be reversed by a few thioesterases or hydrolases. Numerous soluble and membrane-attached proteins are known to be palmitoylated, but among the approximately 400 solute carriers that are classified in 66 families, only 15 found in 8 families have so far been documented to be palmitoylated. Among the best-characterized transporters are the glucose transporters GLUT1 (SLC2A1) and GLUT4 (SLC2A4), the three monoamine transporters norepinephrine transporter (NET; SLC6A2), dopamine transporter (DAT; SLC6A3), and serotonin transporter (SERT; SLC6A4), and the sodium-calcium exchanger NCX1 (SLC8A1). While there is evidence from recent proteomics experiments that numerous solute carriers are palmitoylated, no details beyond the 15 transporters covered in this review are available.
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Affiliation(s)
- Cecilia E Villanueva
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS 66160, United States
| | - Bruno Hagenbuch
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS 66160, United States.
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2
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Bulatova L, Savenkova D, Nurgalieva A, Reshetnikova D, Timonina A, Skripova V, Bogdanov M, Kiyamova R. Toward a Topology-Based Therapeutic Design of Membrane Proteins: Validation of NaPi2b Topology in Live Ovarian Cancer Cells. Front Mol Biosci 2022; 9:895911. [PMID: 35911971 PMCID: PMC9335355 DOI: 10.3389/fmolb.2022.895911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 06/22/2022] [Indexed: 11/13/2022] Open
Abstract
NaPi2b is a sodium-dependent phosphate transporter that belongs to the SLC34 family of transporters which is mainly responsible for phosphate homeostasis in humans. Although NaPi2b is widely expressed in normal tissues, its overexpression has been demonstrated in ovarian, lung, and other cancers. A valuable set of antibodies, including L2 (20/3) and MX35, and its humanized versions react strongly with an antigen on the surface of ovarian and other carcinoma cells. Although the topology of NaPi2b was predicted in silico, no direct experimental data are available for the orientation of NaPi2b extracellular domains in cancer cells. The presented results of antibody mapping of untagged NaPi2b in live ovarian carcinoma cells OVCAR-4 provide a platform for current and future epitope-based cancer therapies and serological diagnostics.
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Affiliation(s)
- Leisan Bulatova
- Research Laboratory “Biomarker”, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
| | - Daria Savenkova
- Research Laboratory “Biomarker”, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
| | - Alsina Nurgalieva
- Research Laboratory “Biomarker”, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
| | - Daria Reshetnikova
- Research Laboratory “Biomarker”, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
| | - Arina Timonina
- Research Laboratory “Biomarker”, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
| | - Vera Skripova
- Research Laboratory “Biomarker”, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
| | - Mikhail Bogdanov
- Research Laboratory “Biomarker”, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
- Department of Biochemistry and Molecular Biology, McGovern Medical School, the University of Texas Health Science Center, Houston, TX, United States
- *Correspondence: Ramziya Kiyamova, ; Mikhail Bogdanov,
| | - Ramziya Kiyamova
- Research Laboratory “Biomarker”, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
- *Correspondence: Ramziya Kiyamova, ; Mikhail Bogdanov,
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3
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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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4
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Gorinski N, Wojciechowski D, Guseva D, Abdel Galil D, Mueller FE, Wirth A, Thiemann S, Zeug A, Schmidt S, Zareba-Kozioł M, Wlodarczyk J, Skryabin BV, Glage S, Fischer M, Al-Samir S, Kerkenberg N, Hohoff C, Zhang W, Endeward V, Ponimaskin E. DHHC7-mediated palmitoylation of the accessory protein barttin critically regulates the functions of ClC-K chloride channels. J Biol Chem 2020; 295:5970-5983. [PMID: 32184353 DOI: 10.1074/jbc.ra119.011049] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 03/13/2020] [Indexed: 12/21/2022] Open
Abstract
Barttin is the accessory subunit of the human ClC-K chloride channels, which are expressed in both the kidney and inner ear. Barttin promotes trafficking of the complex it forms with ClC-K to the plasma membrane and is involved in activating this channel. Barttin undergoes post-translational palmitoylation that is essential for its functions, but the enzyme(s) catalyzing this post-translational modification is unknown. Here, we identified zinc finger DHHC-type containing 7 (DHHC7) protein as an important barttin palmitoyl acyltransferase, whose depletion affected barttin palmitoylation and ClC-K-barttin channel activation. We investigated the functional role of barttin palmitoylation in vivo in Zdhhc7 -/- mice. Although palmitoylation of barttin in kidneys of Zdhhc7 -/- animals was significantly decreased, it did not pathologically alter kidney structure and functions under physiological conditions. However, when Zdhhc7 -/- mice were fed a low-salt diet, they developed hyponatremia and mild metabolic alkalosis, symptoms characteristic of human Bartter syndrome (BS) type IV. Of note, we also observed decreased palmitoylation of the disease-causing R8L barttin variant associated with human BS type IV. Our results indicate that dysregulated DHHC7-mediated barttin palmitoylation appears to play an important role in chloride channel dysfunction in certain BS variants, suggesting that targeting DHHC7 activity may offer a potential therapeutic strategy for reducing hypertension.
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Affiliation(s)
- Nataliya Gorinski
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | | | - Daria Guseva
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Dalia Abdel Galil
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Franziska E Mueller
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Alexander Wirth
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Stefan Thiemann
- Institute for Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Andre Zeug
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Silke Schmidt
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Monika Zareba-Kozioł
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Jakub Wlodarczyk
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Boris V Skryabin
- Department of Medicine, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), University of Münster, 48149 Münster, Germany
| | - Silke Glage
- Institute for Laboratory Animal Science, Hannover Medical School, 30625 Hannover, Germany
| | - Martin Fischer
- Institute for Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Samer Al-Samir
- Institute of Vegetative Physiology, Hannover Medical School, 30625 Hannover, Germany
| | - Nicole Kerkenberg
- Department of Psychiatry and Psychotherapy, Laboratory for Molecular Psychiatry, University of Münster, 48149 Münster, Germany; Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, 48149 Münster, Germany
| | - Christa Hohoff
- Department of Psychiatry and Psychotherapy, Laboratory for Molecular Psychiatry, University of Münster, 48149 Münster, Germany
| | - Weiqi Zhang
- Department of Psychiatry and Psychotherapy, Laboratory for Molecular Psychiatry, University of Münster, 48149 Münster, Germany; Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, 48149 Münster, Germany
| | - Volker Endeward
- Institute of Vegetative Physiology, Hannover Medical School, 30625 Hannover, Germany
| | - Evgeni Ponimaskin
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany.
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Hernando N, Wagner CA. Mechanisms and Regulation of Intestinal Phosphate Absorption. Compr Physiol 2018; 8:1065-1090. [PMID: 29978897 DOI: 10.1002/cphy.c170024] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
States of hypo- and hyperphosphatemia have deleterious consequences including rickets/osteomalacia and renal/cardiovascular disease, respectively. Therefore, the maintenance of appropriate plasma levels of phosphate is an essential requirement for health. This control is executed by the collaborative action of intestine and kidney whose capacities to (re)absorb phosphate are regulated by a number of hormonal and metabolic factors, among them parathyroid hormone, fibroblast growth factor 23, 1,25(OH)2 vitamin D3 , and dietary phosphate. The molecular mechanisms responsible for the transepithelial transport of phosphate across enterocytes are only partially understood. Indeed, whereas renal reabsorption entirely relies on well-characterized active transport mechanisms of phosphate across the renal proximal epithelia, intestinal absorption proceeds via active and passive mechanisms, with the molecular identity of the passive component still unknown. The active absorption of phosphate depends mostly on the activity and expression of the sodium-dependent phosphate cotransporter NaPi-IIb (SLC34A2), which is highly regulated by many of the factors, mentioned earlier. Physiologically, the contribution of NaPi-IIb to the maintenance of phosphate balance appears to be mostly relevant during periods of low phosphate availability. Therefore, its role in individuals living in industrialized societies with high phosphate intake is probably less relevant. Importantly, small increases in plasma phosphate, even within normal range, associate with higher risk of cardiovascular disease. Therefore, therapeutic approaches to treat hyperphosphatemia, including dietary phosphate restriction and phosphate binders, aim at reducing intestinal absorption. Here we review the current state of research in the field. © 2017 American Physiological Society. Compr Physiol 8:1065-1090, 2018.
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Affiliation(s)
- Nati Hernando
- National Center for Competence in Research NCCR Kidney.CH, Institute of Physiology, University Zurich-Irchel, Zurich, Switzerland
| | - Carsten A Wagner
- National Center for Competence in Research NCCR Kidney.CH, Institute of Physiology, University Zurich-Irchel, Zurich, Switzerland
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6
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Chen P, Huang Y, Bayir A, Wang C. Characterization of the isoforms of type IIb sodium-dependent phosphate cotransporter (Slc34a2) in yellow catfish, Pelteobagrus fulvidraco, and their vitamin D 3-regulated expression under low-phosphate conditions. FISH PHYSIOLOGY AND BIOCHEMISTRY 2017; 43:229-244. [PMID: 27620186 DOI: 10.1007/s10695-016-0282-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 08/27/2016] [Indexed: 06/06/2023]
Abstract
In this study, two isoforms slc34a2 genes (type IIb sodium-dependent phosphate cotransporter), slc34a2a2 and slc34a2b, were cloned from intestine and kidney of yellow catfish (Pelteobagrus fulvidraco), with rapid amplification of cDNA ends. The structure differences and the regulation effects of dietary VD3 under low phosphorus were compared among three isoforms of slc34a2 in yellow catfish. The predicted Slc34a2a2 and Slc34a2b proteins match 65 % and 53.8 % sequence identity, with Slc34a2a1, respectively. The membrane-spanning domains were different among these three isoforms. Intestinal Slc34a2a1 and Slc34a2a2 proteins had eight and eleven transmembrane domains, while renal Slc34a2b protein had nine. The tissue distribution study showed that same as slc34a2a1, slc34a2a2 mRNA was mainly distributed in intestine and slc34a2b mRNA in kidney. The effect of vitamin D3 (VD3) level on slc34a2 subfamily expression under low-phosphate conditions, induced by the addition of 0 (VD0), 324 (VD1), 1243 (VD2), 3621 (VD3), 8040 (VD4), or 22700 (VD5) IU VD3/kg feed, was assessed by qPCR. The dose-responsive expression of intestinal slc34a2a2 and high expression of intestinal slc34a2a2 in VD5 together with peak expression of kidney slc34a2b in VD3 coincided with the accumulation of body phosphate content. These data suggested that appropriate level of dietary VD3 up-regulated slc34a2a1, slc34a2a2, and slc34a2b mRNA levels, which increased phosphate retention. In conclusion, the current study provided another possible approach to improve dietary phosphate utilization by adding appropriate level of VD3 to a low-phosphate diet to regulate intestinal and renal slc34a2 gene expression and thus minimize the excretion of phosphorus in yellow catfish.
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Affiliation(s)
- Pei Chen
- The College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, 430070, People's Republic of China
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, People's Republic of China
| | - Yanqing Huang
- East China Sea Fisheries Research Institute, Chinese Academy of Fishery Science, Shanghai, 200090, People's Republic of China
| | - Abdulkadir Bayir
- Department of Aquaculture, Faculty of Fisheries, Atatürk University, 25240, Erzurum, Turkey
| | - Chunfang Wang
- The College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
- Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, 430070, People's Republic of China.
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, People's Republic of China.
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7
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Werner A, Patti M, Zinad HS, Fearn A, Laude A, Forster I. Molecular determinants of transport function in zebrafish Slc34a Na-phosphate transporters. Am J Physiol Regul Integr Comp Physiol 2016; 311:R1213-R1222. [PMID: 27784684 DOI: 10.1152/ajpregu.00020.2016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 10/14/2016] [Accepted: 10/14/2016] [Indexed: 11/22/2022]
Abstract
The epithelial Na+-coupled phosphate cotransporter family Slc34a (NaPi-II) is well conserved in vertebrates and plays an essential role in maintaining whole body levels of inorganic phosphate (Pi). A three-dimensional model of the transport protein has recently been proposed with defined substrate coordination sites. Zebrafish express two NaPi-II isoforms with high sequence identity but a 10-fold different apparent Km for Pi ([Formula: see text]). We took advantage of the two zebrafish isoforms to investigate the contribution of specific amino acids to Pi coordination and transport. Mutations were introduced to gradually transform the low-affinity isoform into a high-affinity transporter. The constructs were expressed in Xenopus laevis oocytes and functionally characterized. Becaue the cotransport of Pi and Na involves multiple steps that could all influence [Formula: see text], we performed a detailed functional analysis to characterize the impact of the mutations on particular steps of the transport cycle. We used varying concentrations of the substrates Pi and its slightly larger analog, arsenate, as well as the cosubstrate, Na+ Moreover, electrogenic kinetics were performed to assess intramolecular movements of the transporter. All of the mutations were found to affect multiple transport steps, which suggested that the altered amino acids induced subtle structural changes rather than coordinating Pi directly. The likely positions of the critical residues were mapped to the model of human Slc34a, and their localization in relation to the proposed substrate binding pockets concurs well with the observed functional data.
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Affiliation(s)
- Andreas Werner
- Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom;
| | - Monica Patti
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, Zürich, Switzerland; and
| | - Hany S Zinad
- Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
| | - Amy Fearn
- Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
| | - Alex Laude
- Bio-Imaging Unit, Medical School, University of Newcastle upon Tyne, United Kingdom
| | - Ian Forster
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, Zürich, Switzerland; and
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Fang R, Xiang Z, Cao M, He J. Different phosphate transport in the duodenum and jejunum of chicken response to dietary phosphate adaptation. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2014; 25:1457-65. [PMID: 25049503 PMCID: PMC4093023 DOI: 10.5713/ajas.2012.12187] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 06/24/2012] [Accepted: 06/02/2012] [Indexed: 12/29/2022]
Abstract
Intestinal phosphate (Pi) absorption across the apical membrane of small intestinal epithelial cells is mainly mediated by the type IIb Na-coupled phosphate co-transporter (NaPi-IIb), but its expression and regulation in the chicken remain unclear. In the present study, we investigated the mRNA and protein levels of NaPi-IIb in three regions of chicken small intestine, and related their expression levels to the rate of net phosphate absorption. Our results showed that maximal phosphate absorption occurs in the jejunum, however the highest expression levels of NaPi-IIb mRNA and protein occurs in the duodenum. In response to a low-Pi diet (TP 0.2%), there is an adaptive response restricted to the duodenum, with increased brush border membrane (BBM) Na-Pi transport activity and NaPi-IIb protein and mRNA abundance. However, when switched from a low- (TP 0.2%) to a normal diet (TP 0.6%) for 4 h, there is an increase in BBM NaPi-IIb protein abundance in the jejunum, but no changes in BBM NaPi-IIb mRNA. Therefore, our study indicates that Na-Pi transport activity and NaPi-IIb protein expression are differentially regulated in the duodenum vs the jejunum in the chicken.
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Affiliation(s)
- Rejun Fang
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan Province 453003, China
| | - Zhifeng Xiang
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan Province 453003, China
| | - Manhu Cao
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan Province 453003, China
| | - Jia He
- College of Animal Science, Henan Institute of Science and Technology, Xinxiang, Henan Province 453003, China
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10
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Sabbagh Y, Giral H, Caldas Y, Levi M, Schiavi SC. Intestinal phosphate transport. Adv Chronic Kidney Dis 2011; 18:85-90. [PMID: 21406292 PMCID: PMC3071860 DOI: 10.1053/j.ackd.2010.11.004] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 11/03/2010] [Accepted: 11/12/2010] [Indexed: 12/14/2022]
Abstract
Phosphate is absorbed in the small intestine by a minimum of 2 distinct mechanisms: paracellular phosphate transport which is dependent on passive diffusion, and active transport which occurs through the sodium-dependent phosphate cotransporters. Despite evidence emerging for other ions, regulation of the phosphate-specific paracellular pathways remains largely unexplored. In contrast, there is a growing body of evidence that active transport through the sodium-dependent phosphate cotransporter, Npt2b, is highly regulated by a diverse set of hormones and dietary conditions. Furthermore, conditional knockout of Npt2b suggests that it plays an important role in maintenance of phosphate homeostasis by coordinating intestinal phosphate absorption with renal phosphate reabsorption. The knockout mouse also suggests that Npt2b is responsible for the majority of sodium-dependent phosphate uptake. The type-III sodium-dependent phosphate transporters, Pit1 and Pit2, contribute to a minor role in total phosphate uptake. Despite coexpression along the apical membrane, differential responses of Pit1 and Npt2b regulation to chronic versus dietary changes illustrates another layer of phosphate transport control. Finally, a major problem in patients with CKD is management of hyperphosphatemia. The present evidence suggests that targeting key regulatory pathways of intestinal phosphate transport may provide novel therapeutic approaches for patients with CKD.
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Affiliation(s)
- Yves Sabbagh
- Endocrine and Renal Sciences, Genzyme Corporation, Framingham, MA, USA
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11
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Forster I, Hernando N, Sorribas V, Werner A. Phosphate transporters in renal, gastrointestinal, and other tissues. Adv Chronic Kidney Dis 2011; 18:63-76. [PMID: 21406290 DOI: 10.1053/j.ackd.2011.01.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 01/17/2011] [Accepted: 01/18/2011] [Indexed: 11/11/2022]
Abstract
Inorganic phosphate (Pi) is essential for all living organisms. Bound to organic molecules, Pi fulfills structural, metabolic, and signaling tasks. Therefore, cell growth and maintenance depends on efficient transport of Pi across cellular membranes into the intracellular space. Uptake of Pi requires energy because the substrate is transported against its electrochemical gradient. Till recently, 2 major families of physiologically relevant Pi-specific transporters have been identified: the solute carrier families Slc34 and Slc20. Interestingly, phylogenetic links can be detected between prokaryotic and eukaryotic transporters in both families. Because less complex model organisms are often instrumental in establishing paradigms for protein function in human beings, a brief assessment of Slc34 and Slc20 phylogeny is of interest.
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12
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Corbeil D, Marzesco AM, Fargeas CA, Huttner WB. Prominin-1: a distinct cholesterol-binding membrane protein and the organisation of the apical plasma membrane of epithelial cells. Subcell Biochem 2010; 51:399-423. [PMID: 20213552 DOI: 10.1007/978-90-481-8622-8_14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The apical plasma membrane of polarized epithelial cells is composed of distinct subdomains, that is, planar regions and protrusions (microvilli, primary cilium), each of which are constructed from specific membrane microdomains. Assemblies containing the pentaspan glycoprotein prominin-1 and certain membrane lipids, notably cholesterol, are characteristic features of these microdomains in apical membrane protrusions. Here we highlight the recent findings concerning the molecular architecture of the apical plasma membrane of epithelial cells and its dynamics. The latter is illustrated by the budding and fission of prominin-1-containing membrane vesicles from apical plasma membrane protrusions, which is controlled, at least in part, by the level of membrane cholesterol and the cholesterol-dependent organization of membrane microdomains.
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Affiliation(s)
- Denis Corbeil
- Tissue Engineering Laboratories, BIOTEC, Technische Universität Dresden, Tatzberg 47-49, 01307, Dresden, Germany.
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13
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Giral H, Caldas Y, Sutherland E, Wilson P, Breusegem S, Barry N, Blaine J, Jiang T, Wang XX, Levi M. Regulation of rat intestinal Na-dependent phosphate transporters by dietary phosphate. Am J Physiol Renal Physiol 2009; 297:F1466-75. [PMID: 19675183 PMCID: PMC2781338 DOI: 10.1152/ajprenal.00279.2009] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Accepted: 08/06/2009] [Indexed: 02/05/2023] Open
Abstract
Hyperphosphatemia associated with chronic kidney disease is one of the factors that can promote vascular calcification, and intestinal P(i) absorption is one of the pharmacological targets that prevents it. The type II Na-P(i) cotransporter NaPi-2b is the major transporter that mediates P(i) reabsorption in the intestine. The potential role and regulation of other Na-P(i) transporters remain unknown. We have identified expression of the type III Na-P(i) cotransporter PiT-1 in the apical membrane of enterocytes. Na-P(i) transport activity and NaPi-2b and PiT-1 proteins are mostly expressed in the duodenum and jejunum of rat small intestine; their expression is negligible in the ileum. In response to a chronic low-P(i) diet, there is an adaptive response restricted to the jejunum, with increased brush border membrane (BBM) Na-P(i) transport activity and NaPi-2b, but not PiT-1, protein and mRNA abundance. However, in rats acutely switched from a low- to a high-P(i) diet, there is an increase in BBM Na-P(i) transport activity in the duodenum that is associated with an increase in BBM NaPi-2b protein abundance. Acute adaptive upregulation is restricted to the duodenum and induces an increase in serum P(i) that produces a transient postprandial hyperphosphatemia. Our study, therefore, indicates that Na-P(i) transport activity and NaPi-2b protein expression are differentially regulated in the duodenum vs. the jejunum and that postprandial upregulation of NaPi-2b could be a potential target for treatment of hyperphosphatemia.
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MESH Headings
- Animals
- Blotting, Western
- Cell Membrane/metabolism
- Duodenum/drug effects
- Duodenum/metabolism
- Enterocytes/metabolism
- Intestine, Small/drug effects
- Intestine, Small/metabolism
- Jejunum/drug effects
- Jejunum/metabolism
- Male
- Microscopy, Fluorescence
- Microvilli/drug effects
- Microvilli/metabolism
- Phosphates/pharmacology
- Phosphorus, Dietary/pharmacology
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Rats
- Rats, Sprague-Dawley
- Sodium-Phosphate Cotransporter Proteins/biosynthesis
- Sodium-Phosphate Cotransporter Proteins, Type III/biosynthesis
- Sodium-Phosphate Cotransporter Proteins, Type III/genetics
- Sodium-Phosphate Cotransporter Proteins, Type IIb/biosynthesis
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Affiliation(s)
- Hector Giral
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, and Veterans Affairs Medical Center, Aurora, CO 80045, USA.
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