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Abstract
While the involvement of actin polymerization in cell migration is well-established, much less is known about the role of transmembrane water flow in cell motility. Here, we investigate the role of water influx in a prototypical migrating cell, the neutrophil, which undergoes rapid, directed movement to sites of injury, and infection. Chemoattractant exposure both increases cell volume and potentiates migration, but the causal link between these processes are not known. We combine single-cell volume measurements and a genome-wide CRISPR screen to identify the regulators of chemoattractant-induced neutrophil swelling, including NHE1, AE2, PI3K-gamma, and CA2. Through NHE1 inhibition in primary human neutrophils, we show that cell swelling is both necessary and sufficient for the potentiation of migration following chemoattractant stimulation. Our data demonstrate that chemoattractant-driven cell swelling complements cytoskeletal rearrangements to enhance migration speed.
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Affiliation(s)
- Tamas L Nagy
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Cardiovascular Research Institute, University of California, San FranciscoSan FranciscoUnited States
| | - Evelyn Strickland
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Cardiovascular Research Institute, University of California, San FranciscoSan FranciscoUnited States
| | - Orion D Weiner
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Cardiovascular Research Institute, University of California, San FranciscoSan FranciscoUnited States
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2
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Nagy TL, Strickland E, Weiner OD. Neutrophils actively swell to potentiate rapid migration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.15.540704. [PMID: 37292824 PMCID: PMC10245588 DOI: 10.1101/2023.05.15.540704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
While the involvement of actin polymerization in cell migration is well-established, much less is known about the role of transmembrane water flow in cell motility. Here, we investigate the role of water influx in a prototypical migrating cell, the neutrophil, which undergoes rapid, directed movement to sites of injury and infection. Chemoattractant exposure both increases cell volume and potentiates migration, but the causal link between these processes is not known. We combine single cell volume measurements and a genome-wide CRISPR screen to identify the regulators of chemoattractant-induced neutrophil swelling, including NHE1, AE2, PI3K-gamma, and CA2. Through NHE1 inhibition in primary human neutrophils, we show that cell swelling is both necessary and sufficient for the potentiation of migration following chemoattractant stimulation. Our data demonstrate that chemoattractant-driven cell swelling complements cytoskeletal rearrangements to enhance migration speed.
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Affiliation(s)
- Tamas L Nagy
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
| | - Evelyn Strickland
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
| | - Orion D Weiner
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
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3
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García-Llorca A, Carta F, Supuran CT, Eysteinsson T. Carbonic anhydrase, its inhibitors and vascular function. Front Mol Biosci 2024; 11:1338528. [PMID: 38348465 PMCID: PMC10859760 DOI: 10.3389/fmolb.2024.1338528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 01/03/2024] [Indexed: 02/15/2024] Open
Abstract
It has been known for some time that Carbonic Anhydrase (CA, EC 4.2.1.1) plays a complex role in vascular function, and in the regulation of vascular tone. Clinically employed CA inhibitors (CAIs) are used primarily to lower intraocular pressure in glaucoma, and also to affect retinal blood flow and oxygen saturation. CAIs have been shown to dilate vessels and increase blood flow in both the cerebral and ocular vasculature. Similar effects of CAIs on vascular function have been observed in the liver, brain and kidney, while vessels in abdominal muscle and the stomach are unaffected. Most of the studies on the vascular effects of CAIs have been focused on the cerebral and ocular vasculatures, and in particular the retinal vasculature, where vasodilation of its vessels, after intravenous infusion of sulfonamide-based CAIs can be easily observed and measured from the fundus of the eye. The mechanism by which CAIs exert their effects on the vasculature is still unclear, but the classic sulfonamide-based inhibitors have been found to directly dilate isolated vessel segments when applied to the extracellular fluid. Modification of the structure of CAI compounds affects their efficacy and potency as vasodilators. CAIs of the coumarin type, which generally are less effective in inhibiting the catalytically dominant isoform hCA II and unable to accept NO, have comparable vasodilatory effects as the primary sulfonamides on pre-contracted retinal arteriolar vessel segments, providing insights into which CA isoforms are involved. Alterations of the lipophilicity of CAI compounds affect their potency as vasodilators, and CAIs that are membrane impermeant do not act as vasodilators of isolated vessel segments. Experiments with CAIs, that shed light on the role of CA in the regulation of vascular tone of vessels, will be discussed in this review. The role of CA in vascular function will be discussed, with specific emphasis on findings with the effects of CA inhibitors (CAI).
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Affiliation(s)
- Andrea García-Llorca
- Department of Physiology, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - Fabrizio Carta
- NEUROFARBA Department, Section of Pharmaceutical and Nutraceutical Sciences, University of Florence, Florence, Italy
| | - Claudiu T. Supuran
- NEUROFARBA Department, Section of Pharmaceutical and Nutraceutical Sciences, University of Florence, Florence, Italy
| | - Thor Eysteinsson
- Department of Physiology, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
- Department of Ophthalmology, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
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4
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Huang X, Winter D, Glover DJ, Supuran CT, Donald WA. Effects of Phosphorylation on the Activity, Inhibition and Stability of Carbonic Anhydrases. Int J Mol Sci 2023; 24:ijms24119275. [PMID: 37298228 DOI: 10.3390/ijms24119275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 06/12/2023] Open
Abstract
Carbonic anhydrases (CAs) are a metalloenzyme family that have important roles in cellular processes including pH homeostasis and have been implicated in multiple pathological conditions. Small molecule inhibitors have been developed to target carbonic anhydrases, but the effects of post-translational modifications (PTMs) on the activity and inhibition profiles of these enzymes remain unclear. Here, we investigate the effects of phosphorylation, the most prevalent carbonic anhydrase PTM, on the activities and drug-binding affinities of human CAI and CAII, two heavily modified active isozymes. Using serine to glutamic acid (S > E) mutations to mimic the effect of phosphorylation, we demonstrate that phosphomimics at a single site can significantly increase or decrease the catalytic efficiencies of CAs, depending on both the position of the modification and the CA isoform. We also show that the S > E mutation at Ser50 of hCAII decreases the binding affinities of hCAII with well-characterized sulphonamide inhibitors including by over 800-fold for acetazolamide. Our findings suggest that CA phosphorylation may serve as a regulatory mechanism for enzymatic activity, and affect the binding affinity and specificity of small, drug and drug-like molecules. This work should motivate future studies examining the PTM-modification forms of CAs and their distributions, which should provide insights into CA physiopathological functions and facilitate the development of 'modform-specific' carbonic anhydrase inhibitors.
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Affiliation(s)
- Xiaojing Huang
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
| | - Daniel Winter
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
| | - Dominic J Glover
- School of Biotechnology & Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Claudiu T Supuran
- Neurofarba Department, Sezione di Scienze Farmaceutiche, Universita degli Studi di Firenze, Via Ugo Schiff 6, Sesto Fiorentino, 50019 Florence, Italy
| | - William A Donald
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
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5
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Zito F, Bonaventura R, Costa C, Russo R. Carbonic anhydrases in development: morphological observations and gene expression profiling in sea urchin embryos exposed to acetazolamide. Open Biol 2023; 13:220254. [PMID: 36597694 PMCID: PMC9811153 DOI: 10.1098/rsob.220254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Carbonic anhydrases (CANs) are conserved metalloenzymes catalysing the reversible hydration of carbon dioxide into protons and bicarbonate, with important roles in cells physiology. Some CAN-coding genes were found in sea urchin genome, although only one involved in embryonic skeletogenesis was described in Paracentrotus lividus. Here, we investigated gene expression patterns of P. lividus embryos cultured in the presence of acetazolamide (AZ), a CAN inhibitor, to combine morphological defects with their molecular underpinning. CAN inhibition blocked skeletogenesis, affected the spatial/temporal expression of some biomineralization-related genes, inhibited embryos swimming. A comparative analysis on the expression of 127 genes in control and 3 h/24 h AZ-treated embryos, using NanoString technology, showed the differential expression of genes encoding for structural/regulatory proteins, with different embryonic roles: biomineralization, transcriptional regulation, signalling, development and defence response. The study of the differentially expressed genes and the signalling pathways affected, besides in silico analyses and a speculative 'interactomic model', leads to predicting the presence of various CAN isoforms, possibly involved in different physiological processes/activities in sea urchin embryo, and their potential target genes/proteins. Our findings provide new valuable molecular data for further studies in several biological fields: developmental biology (biomineralization, axes patterning), cell differentiation (neural development) and drug toxicology (AZ effects on embryos/tissues).
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Affiliation(s)
- Francesca Zito
- Istituto per la Ricerca e l'Innovazione Biomedica, Consiglio Nazionale delle Ricerche, via Ugo La Malfa 153, Palermo 90146, Italy
| | - Rosa Bonaventura
- Istituto per la Ricerca e l'Innovazione Biomedica, Consiglio Nazionale delle Ricerche, via Ugo La Malfa 153, Palermo 90146, Italy
| | - Caterina Costa
- Istituto per la Ricerca e l'Innovazione Biomedica, Consiglio Nazionale delle Ricerche, via Ugo La Malfa 153, Palermo 90146, Italy
| | - Roberta Russo
- Istituto per la Ricerca e l'Innovazione Biomedica, Consiglio Nazionale delle Ricerche, via Ugo La Malfa 153, Palermo 90146, Italy
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6
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Li X, Buckley B, Stoletov K, Jing Y, Ranson M, Lewis JD, Kelso M, Fliegel L. Roles of the Na +/H + Exchanger Isoform 1 and Urokinase in Prostate Cancer Cell Migration and Invasion. Int J Mol Sci 2021; 22:ijms222413263. [PMID: 34948058 PMCID: PMC8705693 DOI: 10.3390/ijms222413263] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/02/2021] [Accepted: 12/06/2021] [Indexed: 01/06/2023] Open
Abstract
Prostate cancer is a leading cause of cancer-associated deaths in men over 60 years of age. Most patients are killed by tumor metastasis. Recent evidence has implicated a role of the tumor microenvironment and urokinase plasminogen activator (uPA) in cancer cell migration, invasion, and metastasis. Here, we examine the role of the Na+/H+ exchanger isoform 1 (NHE1) and uPA in DU 145 prostate cancer cell migration and colony formation. Knockout of NHE1 reduced cell migration. The effects of a series of novel NHE1/uPA hexamethylene-amiloride-based inhibitors with varying efficacy towards NHE1 and uPA were examined on prostate cancer cells. Inhibition of NHE1-alone, or with inhibitors combining NHE1 or uPA inhibition-generally did not prevent prostate cancer cell migration. However, uPA inhibition-but not NHE1 inhibition-prevented anchorage-dependent colony formation. Application of inhibitors at concentrations that only saturate uPA inhibition decreased tumor invasion in vivo. The results suggest that while knockout of NHE1 affects cell migration, these effects are not due to NHE1-dependent proton translocation. Additionally, while neither NHE1 nor uPA activity was critical in cell migration, only uPA activity appeared to be critical in anchorage-dependent colony formation of DU 145 prostate cancer cells and invasion in vivo.
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Affiliation(s)
- Xiuju Li
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada; (X.L.); (Y.J.)
| | - Benjamin Buckley
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (B.B.); (M.R.); (M.K.)
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Konstantin Stoletov
- Department of Oncology, University of Alberta, Edmonton, AB T6G 2H7, Canada; (K.S.); (J.D.L.)
| | - Yang Jing
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada; (X.L.); (Y.J.)
| | - Marie Ranson
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (B.B.); (M.R.); (M.K.)
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia
| | - John D. Lewis
- Department of Oncology, University of Alberta, Edmonton, AB T6G 2H7, Canada; (K.S.); (J.D.L.)
| | - Mike Kelso
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (B.B.); (M.R.); (M.K.)
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Larry Fliegel
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada; (X.L.); (Y.J.)
- Correspondence: ; Tel.: +1-780-492-1848
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7
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Amino Acids 785, 787 of the Na +/H + Exchanger Cytoplasmic Tail Modulate Protein Activity and Tail Conformation. Int J Mol Sci 2021; 22:ijms222111349. [PMID: 34768780 PMCID: PMC8583816 DOI: 10.3390/ijms222111349] [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: 09/20/2021] [Revised: 10/14/2021] [Accepted: 10/18/2021] [Indexed: 11/30/2022] Open
Abstract
The mammalian Na+/H+ exchanger isoform 1 (NHE1) is a plasma membrane protein ubiquitously present in humans. It regulates intracellular pH by removing an intracellular proton in exchange for an extracellular sodium. It consists of a 500 amino acid membrane domain plus a 315 amino acid, regulatory cytosolic tail. Here, we investigated the effect of mutation of two amino acids of the regulatory tail, Ser785 and Ser787, that were similar in location and context to two amino acids of the Arabidopsis Na+/H+ exchanger SOS1. Mutation of these two amino acids to either Ala or phosphomimetic Glu did not affect surface targeting but led to a slight reduction in the level of protein expressed. The activity of the NHE1 protein was reduced in the phosphomimetic mutations and the effect was due to a decrease in Vmax activity. The Ser to Glu mutations also caused a change in the apparent molecular weight of both the full-length protein and of the cytosolic tail of NHE1. A conformational change in this region was indicated by differential trypsin sensitivity. We also found that a peptide containing amino acids 783–790 bound to several more proximal regions of the NHE1 tail in in vitro protein interaction experiments. The results are the first characterization of these two amino acids and show that they have significant effects on enzyme kinetics and the structure of the NHE1 protein.
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8
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Nolly MB, Vargas LA, Correa MV, Lofeudo JM, Pinilla AO, Rueda JOV, Guerrero-Gimenez ME, Swenson ER, Damiani MT, Alvarez BV. Carbonic anhydrase IX and hypoxia-inducible factor 1 attenuate cardiac dysfunction after myocardial infarction. Pflugers Arch 2021; 473:1273-1285. [PMID: 34231059 DOI: 10.1007/s00424-021-02592-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/04/2021] [Accepted: 02/08/2021] [Indexed: 01/11/2023]
Abstract
Myocardial infarction (MI) is one of the leading causes of death worldwide. Prognosis and mortality rate are directly related to infarct size and post-infarction pathological heart remodeling, which can lead to heart failure. Hypoxic MI-affected areas increase the expression of hypoxia-inducible factor (HIF-1), inducing infarct size reduction and improving cardiac function. Hypoxia translocates HIF-1 to the nucleus, activating carbonic anhydrase IX (CAIX) transcription. CAIX regulates myocardial intracellular pH, critical for heart performance. Our objective was to investigate CAIX participation and relation with sodium bicarbonate transporters 1 (NBC1) and HIF-1 in cardiac remodeling after MI. We analyzed this pathway in an "in vivo" rat coronary artery ligation model and isolated cardiomyocytes maintained under hypoxia. Immunohistochemical studies revealed an increase in HIF-1 levels after 2 h of infarction. Similar results were observed in 2-h infarcted cardiac tissue (immunoblotting) and in hypoxic cardiomyocytes with a nuclear distribution (confocal microscopy). Immunohistochemical studies showed an increase CAIX in the infarcted area at 2 h, mainly distributed throughout the cell and localized in the plasma membrane at 24 h. Similar results were observed in 2 h in infarcted cardiac tissue (immunoblotting) and in hypoxic cardiomyocytes (confocal microscopy). NBC1 expression increased in cardiac tissue after 2 h of infarction (immunoblotting). CAIX and NBC1 interaction increases in cardiac tissue subjected to MI for 2h when CAIX is present (immunoprecipitation). These results suggest that CAIX interacts with NBC1 in our infarct model as a mechanism to prevent acidic damage in hypoxic tissue, making it a promising therapeutic target.
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Affiliation(s)
- Mariela Beatriz Nolly
- Laboratorio de Bioquímica e Inmunidad, IMBECU-CONICET-UNCuyo, Instituto de Bioquímica y Biotecnología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina.
| | - Lorena Alejandra Vargas
- Centro de Investigaciones Cardiovasculares, CIC-CONICET, Facultad de Medicina, Universidad Nacional de La Plata, La Plata, 1900, Buenos Aires, Argentina
| | - María Verónica Correa
- Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, CIC-PBA, La Plata, 1900, Buenos Aires, Argentina
| | - Juan Manuel Lofeudo
- Centro de Investigaciones Cardiovasculares, CIC-CONICET, Facultad de Medicina, Universidad Nacional de La Plata, La Plata, 1900, Buenos Aires, Argentina
| | - Andrés Oscar Pinilla
- Centro de Investigaciones Cardiovasculares, CIC-CONICET, Facultad de Medicina, Universidad Nacional de La Plata, La Plata, 1900, Buenos Aires, Argentina
| | - Jorge Omar Velez Rueda
- Centro de Investigaciones Cardiovasculares, CIC-CONICET, Facultad de Medicina, Universidad Nacional de La Plata, La Plata, 1900, Buenos Aires, Argentina
| | - Martin E Guerrero-Gimenez
- Laboratorio de Oncología, IMBECU-CONICET-UNCuyo, Instituto de Bioquímica y Biotecnología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina
| | - Erik Richard Swenson
- Medical Service, VA Puget Sound Health Care System, University of Washington, Seattle, WA, USA
| | - Maria Teresa Damiani
- Laboratorio de Bioquímica e Inmunidad, IMBECU-CONICET-UNCuyo, Instituto de Bioquímica y Biotecnología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina
| | - Bernardo Victor Alvarez
- Centro de Investigaciones Cardiovasculares, CIC-CONICET, Facultad de Medicina, Universidad Nacional de La Plata, La Plata, 1900, Buenos Aires, Argentina
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
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9
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Trampert DC, van de Graaf SFJ, Jongejan A, Oude Elferink RPJ, Beuers U. Hepatobiliary acid-base homeostasis: Insights from analogous secretory epithelia. J Hepatol 2021; 74:428-441. [PMID: 33342564 DOI: 10.1016/j.jhep.2020.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/03/2020] [Accepted: 10/19/2020] [Indexed: 12/14/2022]
Abstract
Many epithelia secrete bicarbonate-rich fluid to generate flow, alter viscosity, control pH and potentially protect luminal and intracellular structures from chemical stress. Bicarbonate is a key component of human bile and impaired biliary bicarbonate secretion is associated with liver damage. Major efforts have been undertaken to gain insight into acid-base homeostasis in cholangiocytes and more can be learned from analogous secretory epithelia. Extrahepatic examples include salivary and pancreatic duct cells, duodenocytes, airway and renal epithelial cells. The cellular machinery involved in acid-base homeostasis includes carbonic anhydrase enzymes, transporters of the solute carrier family, and intra- and extracellular pH sensors. This pH-regulatory system is orchestrated by protein-protein interactions, the establishment of an electrochemical gradient across the plasma membrane and bicarbonate sensing of the intra- and extracellular compartment. In this review, we discuss conserved principles identified in analogous secretory epithelia in the light of current knowledge on cholangiocyte physiology. We present a framework for cholangiocellular acid-base homeostasis supported by expression analysis of publicly available single-cell RNA sequencing datasets from human cholangiocytes, which provide insights into the molecular basis of pH homeostasis and dysregulation in the biliary system.
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Affiliation(s)
- David C Trampert
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands
| | - Stan F J van de Graaf
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands
| | - Aldo Jongejan
- Amsterdam UMC, University of Amsterdam, Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Meibergdreef 9, Amsterdam, the Netherlands
| | - Ronald P J Oude Elferink
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands
| | - Ulrich Beuers
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands.
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10
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Koltai T. Targeting the pH Paradigm at the Bedside: A Practical Approach. Int J Mol Sci 2020; 21:E9221. [PMID: 33287221 PMCID: PMC7730959 DOI: 10.3390/ijms21239221] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 11/27/2020] [Accepted: 11/28/2020] [Indexed: 02/07/2023] Open
Abstract
The inversion of the pH gradient in malignant tumors, known as the pH paradigm, is increasingly becoming accepted by the scientific community as a hallmark of cancer. Accumulated evidence shows that this is not simply a metabolic consequence of a dysregulated behavior, but rather an essential process in the physiopathology of accelerated proliferation and invasion. From the over-simplification of increased lactate production as the cause of the paradigm, as initially proposed, basic science researchers have arrived at highly complex and far-reaching knowledge, that substantially modified that initial belief. These new developments show that the paradigm entails a different regulation of membrane transporters, electrolyte exchangers, cellular and membrane enzymes, water trafficking, specialized membrane structures, transcription factors, and metabolic changes that go far beyond fermentative glycolysis. This complex world of dysregulations is still shuttered behind the walls of experimental laboratories and has not yet reached bedside medicine. However, there are many known pharmaceuticals and nutraceuticals that are capable of targeting the pH paradigm. Most of these products are well known, have low toxicity, and are also inexpensive. They need to be repurposed, and this would entail shorter clinical studies and enormous cost savings if we compare them with the time and expense required for the development of a new molecule. Will targeting the pH paradigm solve the "cancer problem"? Absolutely not. However, reversing the pH inversion would strongly enhance standard treatments, rendering them more efficient, and in some cases permitting lower doses of toxic drugs. This article's goal is to describe how to reverse the pH gradient inversion with existing drugs and nutraceuticals that can easily be used in bedside medicine, without adding toxicity to established treatments. It also aims at increasing awareness among practicing physicians that targeting the pH paradigm would be able to improve the results of standard therapies. Some clinical cases will be presented as well, showing how the pH gradient inversion can be treated at the bedside in a simple manner with repurposed drugs.
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Affiliation(s)
- Tomas Koltai
- Centro de Diagnostico y Tratamiento de la Obra Social del Personal de la Alimentacion, Talar de Pacheco, Buenos Aires 1617, Argentina
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11
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Moss FJ, Boron WF. Carbonic anhydrases enhance activity of endogenous Na-H exchangers and not the electrogenic Na/HCO 3 cotransporter NBCe1-A, expressed in Xenopus oocytes. J Physiol 2020; 598:5821-5856. [PMID: 32969493 PMCID: PMC7747792 DOI: 10.1113/jp280143] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 09/07/2020] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS According to the HCO 3 - metabolon hypothesis, direct association of cytosolic carbonic anhydrases (CAs) with the electrogenic Na/HCO3 cotransporter NBCe1-A speeds transport by regenerating/consuming HCO 3 - . The present work addresses published discrepancies as to whether cytosolic CAs stimulate NBCe1-A, heterologously expressed in Xenopus oocytes. We confirm the essential elements of the previous experimental observations, taken as support for the HCO 3 - metabolon hypothesis. However, using our own experimental protocols or those of others, we find that NBCe1-A function is unaffected by cytosolic CAs. Previous conclusions that cytosolic CAs do stimulate NBCe1-A can be explained by an unanticipated stimulatory effect of the CAs on an endogenous Na-H exchanger. Theoretical analyses show that, although CAs could stimulate non- HCO 3 - transporters (e.g. Na-H exchangers) by accelerating CO2 / HCO 3 - -mediated buffering of acid-base equivalents, they could not appreciably affect transport rates of NBCe1 or other transporters carrying HCO 3 - , CO 3 = , or NaCO 3 - ion pairs. ABSTRACT The HCO 3 - metabolon hypothesis predicts that cytosolic carbonic anhydrase (CA) binds to NBCe1-A, promotes HCO 3 - replenishment/consumption, and enhances transport. Using a short step-duration current-voltage (I-V) protocol with Xenopus oocytes expressing eGFP-tagged NBCe1-A, our group reported that neither injecting human CA II (hCA II) nor fusing hCA II to the NBCe1-A carboxy terminus affects background-subtracted NBCe1 slope conductance (GNBC ), which is a direct measure of NBCe1-A activity. Others - using bovine CA (bCA), untagged NBCe1-A, and protocols keeping holding potential (Vh ) far from NBCe1-A's reversal potential (Erev ) for prolonged periods - found that bCA increases total membrane current (ΔIm ), which apparently supports the metabolon hypothesis. We systematically investigated differences in the two protocols. In oocytes expressing untagged NBCe1-A, injected with bCA and clamped to -40 mV, CO2 / HCO 3 - exposures markedly decrease Erev , producing large transient outward currents persisting for >10 min and rapid increases in [Na+ ]i . Although the CA inhibitor ethoxzolamide (EZA) reduces both ΔIm and d[Na+ ]i /dt, it does not reduce GNBC . In oocytes not expressing NBCe1-A, CO2 / HCO 3 - triggers rapid increases in [Na+ ]i that both hCA II and bCA enhance in concentration-dependent manners. These d[Na+ ]i /dt increases are inhibited by EZA and blocked by EIPA, a Na-H exchanger (NHE) inhibitor. In oocytes expressing untagged NBCe1-A and injected with bCA, EIPA abolishes the EZA-dependent decreases in ΔIm and d[Na+ ]i /dt. Thus, CAs/EZA produce their ΔIm and d[Na+ ]i /dt effects not through NBCe1-A, but endogenous NHEs. Theoretical considerations argue against a CA stimulation of HCO 3 - transport, supporting the conclusion that an NBCe1-A- HCO 3 - metabolon does not exist in oocytes.
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Affiliation(s)
- Fraser J. Moss
- Department of Physiology and Biophysics, Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Walter F. Boron
- Department of Physiology and Biophysics, Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Department of Medicine and Department of Biochemistry Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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12
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Ghislat G, Rahman T, Ballester PJ. Identification and Validation of Carbonic Anhydrase II as the First Target of the Anti-Inflammatory Drug Actarit. Biomolecules 2020; 10:biom10111570. [PMID: 33227945 PMCID: PMC7699199 DOI: 10.3390/biom10111570] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/13/2020] [Accepted: 11/16/2020] [Indexed: 12/31/2022] Open
Abstract
Background and purpose: Identifying the macromolecular targets of drug molecules is a fundamental aspect of drug discovery and pharmacology. Several drugs remain without known targets (orphan) despite large-scale in silico and in vitro target prediction efforts. Ligand-centric chemical-similarity-based methods for in silico target prediction have been found to be particularly powerful, but the question remains of whether they are able to discover targets for target-orphan drugs. Experimental Approach: We used one of these in silico methods to carry out a target prediction analysis for two orphan drugs: actarit and malotilate. The top target predicted for each drug was carbonic anhydrase II (CAII). Each drug was therefore quantitatively evaluated for CAII inhibition to validate these two prospective predictions. Key Results: Actarit showed in vitro concentration-dependent inhibition of CAII activity with submicromolar potency (IC50 = 422 nM) whilst no consistent inhibition was observed for malotilate. Among the other 25 targets predicted for actarit, RORγ (RAR-related orphan receptor-gamma) is promising in that it is strongly related to actarit’s indication, rheumatoid arthritis (RA). Conclusion and Implications: This study is a proof-of-concept of the utility of MolTarPred for the fast and cost-effective identification of targets of orphan drugs. Furthermore, the mechanism of action of actarit as an anti-RA agent can now be re-examined from a CAII-inhibitor perspective, given existing relationships between this target and RA. Moreover, the confirmed CAII-actarit association supports investigating the repositioning of actarit on other CAII-linked indications (e.g., hypertension, epilepsy, migraine, anemia and bone, eye and cardiac disorders).
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Affiliation(s)
- Ghita Ghislat
- Centre d’Immunologie de Marseille-Luminy, Inserm, U1104, CNRS UMR7280, F-13288 Marseille, France
- Correspondence: (G.G.); (P.J.B.)
| | - Taufiq Rahman
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK;
| | - Pedro J. Ballester
- Centre de Recherche en Cancérologie de Marseille (CRCM), Inserm, U1068, F-13009 Marseille, France
- CNRS, UMR7258, F-13009 Marseille, France
- Institut Paoli-Calmettes, F-13009 Marseille, France
- Aix-Marseille University, UM 105, F-13284 Marseille, France
- Correspondence: (G.G.); (P.J.B.)
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13
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Role of Genetic Mutations of the Na +/H + Exchanger Isoform 1, in Human Disease and Protein Targeting and Activity. Mol Cell Biochem 2020; 476:1221-1232. [PMID: 33201382 DOI: 10.1007/s11010-020-03984-4] [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] [Received: 06/16/2020] [Accepted: 11/06/2020] [Indexed: 01/22/2023]
Abstract
The mammalian Na+/H+ exchanger isoform one (NHE1) is a plasma membrane protein that is ubiquitously present in human cells. It functions to regulate intracellular pH removing an intracellular proton in exchange for one extracellular sodium and is involved in heart disease and in promoting metastasis in cancer. It is made of a 500 amino acid membrane domain plus a 315 amino acid, regulatory cytosolic tail. The membrane domain is thought to have 12 transmembrane segments and a large membrane-associated extracellular loop. Early studies demonstrated that in mice, disruption of the NHE1 gene results in locomotor ataxia and a phenotype of slow-wave epilepsy. Defects included a progressive neuronal degeneration. Growth and reproductive ability were also reduced. Recent studies have identified human autosomal homozygous recessive mutations in the NHE1 gene (SLC9A1) that result in impaired development, ataxia and other severe defects, and explain the cause of the human disease Lichtenstein-Knorr syndrome. Other human mutations have been identified that are stop codon polymorphisms. These cause short non-functional NHE1 proteins, while other genetic polymorphisms in the NHE1 gene cause impaired expression of the NHE1 protein, reduced activity, enhanced protein degradation or altered kinetic activation of the protein. Since NHE1 plays a key role in many human physiological functions and in human disease, genetic polymorphisms of the protein that significantly alter its function and are likely play significant roles in varying human phenotypes and be involved in disease.
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14
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Role of pH Regulatory Proteins and Dysregulation of pH in Prostate Cancer. Rev Physiol Biochem Pharmacol 2020; 182:85-110. [PMID: 32776252 DOI: 10.1007/112_2020_18] [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: 12/12/2022]
Abstract
Prostate cancer is the fourth most commonly diagnosed cancer, and although it is often a slow-growing malignancy, it is the second leading cause of cancer-associated deaths in men and the first in Europe and North America. In many forms of cancer, when the disease is a solid tumor confined to one organ, it is often readily treated. However, when the cancer becomes an invasive metastatic carcinoma, it is more often fatal. It is therefore of great interest to identify mechanisms that contribute to the invasion of cells to identify possible targets for therapy. During prostate cancer progression, the epithelial cells undergo epithelial-mesenchymal transition that is characterized by morphological changes, a loss of cell-cell adhesion, and invasiveness. Dysregulation of pH has emerged as a hallmark of cancer with a reversed pH gradient and with a constitutively increased intracellular pH that is elevated above the extracellular pH. This phenomenon has been referred to as "a perfect storm" for cancer progression. Acid-extruding ion transporters include the Na+/H+ exchanger NHE1 (SLC9A1), the Na+HCO3- cotransporter NBCn1 (SLC4A7), anion exchangers, vacuolar-type adenosine triphosphatases, and the lactate-H+ cotransporters of the monocarboxylate family (MCT1 and MCT4 (SLC16A1 and 3)). Additionally, carbonic anhydrases contribute to acid transport. Of these, several have been shown to be upregulated in different human cancers including the NBCn1, MCTs, and NHE1. Here the role and contribution of acid-extruding transporters in prostate cancer growth and metastasis were examined. These proteins make significant contributions to prostate cancer progression.
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15
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Bagdonaite I, Pallesen EM, Ye Z, Vakhrushev SY, Marinova IN, Nielsen MI, Kramer SH, Pedersen SF, Joshi HJ, Bennett EP, Dabelsteen S, Wandall HH. O-glycan initiation directs distinct biological pathways and controls epithelial differentiation. EMBO Rep 2020; 21:e48885. [PMID: 32329196 PMCID: PMC7271655 DOI: 10.15252/embr.201948885] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 03/03/2020] [Accepted: 03/16/2020] [Indexed: 12/17/2022] Open
Abstract
Post-translational modifications (PTMs) greatly expand the function and potential for regulation of protein activity, and O-glycosylation is among the most abundant and diverse PTMs. Initiation of O-GalNAc glycosylation is regulated by 20 distinct GalNAc-transferases (GalNAc-Ts), and deficiencies in individual GalNAc-Ts are associated with human disease, causing subtle but distinct phenotypes in model organisms. Here, we generate a set of isogenic keratinocyte cell lines lacking either of the three dominant and differentially expressed GalNAc-Ts. Through the ability of keratinocytes to form epithelia, we investigate the phenotypic consequences of the loss of individual GalNAc-Ts. Moreover, we probe the cellular responses through global transcriptomic, differential glycoproteomic, and differential phosphoproteomic analyses. We demonstrate that loss of individual GalNAc-T isoforms causes distinct epithelial phenotypes through their effect on specific biological pathways; GalNAc-T1 targets are associated with components of the endomembrane system, GalNAc-T2 targets with cell-ECM adhesion, and GalNAc-T3 targets with epithelial differentiation. Thus, GalNAc-T isoforms serve specific roles during human epithelial tissue formation.
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Affiliation(s)
- Ieva Bagdonaite
- Copenhagen Center for Glycomics, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Emil Mh Pallesen
- Copenhagen Center for Glycomics, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Zilu Ye
- Copenhagen Center for Glycomics, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Sergey Y Vakhrushev
- Copenhagen Center for Glycomics, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Irina N Marinova
- Copenhagen Center for Glycomics, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Mathias I Nielsen
- Copenhagen Center for Glycomics, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Signe H Kramer
- Cell Biology and Physiology, Department of Science, University of Copenhagen, Copenhagen, Denmark
| | - Stine F Pedersen
- Cell Biology and Physiology, Department of Science, University of Copenhagen, Copenhagen, Denmark
| | - Hiren J Joshi
- Copenhagen Center for Glycomics, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Eric P Bennett
- Copenhagen Center for Glycomics, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark.,School of Dentistry, University of Copenhagen, Copenhagen, Denmark
| | - Sally Dabelsteen
- School of Dentistry, University of Copenhagen, Copenhagen, Denmark
| | - Hans H Wandall
- Copenhagen Center for Glycomics, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
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16
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Becker HM, Deitmer JW. Transport Metabolons and Acid/Base Balance in Tumor Cells. Cancers (Basel) 2020; 12:cancers12040899. [PMID: 32272695 PMCID: PMC7226098 DOI: 10.3390/cancers12040899] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/03/2020] [Accepted: 04/04/2020] [Indexed: 02/07/2023] Open
Abstract
Solid tumors are metabolically highly active tissues, which produce large amounts of acid. The acid/base balance in tumor cells is regulated by the concerted interplay between a variety of membrane transporters and carbonic anhydrases (CAs), which cooperate to produce an alkaline intracellular, and an acidic extracellular, environment, in which cancer cells can outcompete their adjacent host cells. Many acid/base transporters form a structural and functional complex with CAs, coined "transport metabolon". Transport metabolons with bicarbonate transporters require the binding of CA to the transporter and CA enzymatic activity. In cancer cells, these bicarbonate transport metabolons have been attributed a role in pH regulation and cell migration. Another type of transport metabolon is formed between CAs and monocarboxylate transporters, which mediate proton-coupled lactate transport across the cell membrane. In this complex, CAs function as "proton antenna" for the transporter, which mediate the rapid exchange of protons between the transporter and the surroundings. These transport metabolons do not require CA catalytic activity, and support the rapid efflux of lactate and protons from hypoxic cancer cells to allow sustained glycolytic activity and cell proliferation. Due to their prominent role in tumor acid/base regulation and metabolism, transport metabolons might be promising drug targets for new approaches in cancer therapy.
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Affiliation(s)
- Holger M. Becker
- Institute of Physiological Chemistry, University of Veterinary Medicine Hannover, D-30559 Hannover, Germany
- Correspondence:
| | - Joachim W. Deitmer
- Department of Biology, University of Kaiserslautern, D-67653 Kaiserslautern, Germany;
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17
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Becker HM. Carbonic anhydrase IX and acid transport in cancer. Br J Cancer 2020; 122:157-167. [PMID: 31819195 PMCID: PMC7051959 DOI: 10.1038/s41416-019-0642-z] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/29/2019] [Accepted: 10/22/2019] [Indexed: 02/07/2023] Open
Abstract
Alterations in tumour metabolism and acid/base regulation result in the formation of a hostile environment, which fosters tumour growth and metastasis. Acid/base homoeostasis in cancer cells is governed by the concerted interplay between carbonic anhydrases (CAs) and various transport proteins, which either mediate proton extrusion or the shuttling of acid/base equivalents, such as bicarbonate and lactate, across the cell membrane. Accumulating evidence suggests that some of these transporters interact both directly and functionally with CAIX to form a protein complex coined the 'transport metabolon'. Transport metabolons formed between bicarbonate transporters and CAIX require CA catalytic activity and have a function in cancer cell migration and invasion. Another type of transport metabolon is formed by CAIX and monocarboxylate transporters. In this complex, CAIX functions as a proton antenna for the transporter, which drives the export of lactate and protons from the cell. Since CAIX is almost exclusively expressed in cancer cells, these transport metabolons might serve as promising targets to interfere with tumour pH regulation and energy metabolism. This review provides an overview of the current state of research on the function of CAIX in tumour acid/base transport and discusses how CAIX transport metabolons could be exploited in modern cancer therapy.
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Affiliation(s)
- Holger M Becker
- Institute of Physiological Chemistry, University of Veterinary Medicine Hannover, D-30559, Hannover, Germany.
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18
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Jaquenod De Giusti C, Blanco PG, Lamas PA, Carrizo Velasquez F, Lofeudo JM, Portiansky EL, Alvarez BV. Carbonic anhydrase II/sodium-proton exchanger 1 metabolon complex in cardiomyopathy of ob -/- type 2 diabetic mice. J Mol Cell Cardiol 2019; 136:53-63. [PMID: 31518570 DOI: 10.1016/j.yjmcc.2019.09.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 07/17/2019] [Indexed: 10/26/2022]
Abstract
Heart failure is the leading cause of death among diabetic people. Cellular and molecular entities leading to diabetic cardiomyopathy are, however, poorly understood. Coupling of cardiac carbonic anhydrase II (CAII) and Na+/H+ exchanger 1 (NHE1) to form a transport metabolon was analyzed in obese type 2 diabetic mice (ob-/-) and control heterozygous littermates (ob+/-). Echocardiography showed elevated systolic interventricular septum thickness and systolic posterior wall thickness in ob-/- mice at 9 and 16 weeks. ob-/- mice showed increased left ventricular (LV) weight/tibia length ratio and increased cardiomyocyte cross sectional area as compared to controls, indicating cardiac hypertrophy. Immunoblot analysis showed increased CAII expression in LV samples of ob-/-vs. ob+/- mice, and augmented Ser703 phosphorylation on NHE1 in ob-/- hearts. Reciprocal co-immunoprecipitation analysis showed strong association of CAII and NHE1 in LV samples of ob-/- mice. NHE1-dependent rate of intracellular pH (pHi) normalization after transient acid loading of isolated cardiomyocytes was higher in ob-/- mice vs. ob+/-. NHE transport activity was also augmented in cultured H9C2 rat cardiomyoblasts treated with high glucose/high palmitate, and it was normalized after CA inhibition. We conclude that the NHE1/CAII metabolon complex is exacerbated in diabetic cardiomyopathy of ob-/- mice, which may lead to perturbation of pHi and [Na+] and [Ca2+] handling in these diseased hearts.
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Affiliation(s)
- Carolina Jaquenod De Giusti
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, 1900 La Plata, Argentina; Established Investigators of CONICET, Argentina
| | - Paula G Blanco
- Servicio de Cardiología, Facultad de Ciencias Veterinarias, UNLP, Argentina; Established Investigators of CONICET, Argentina
| | - Paula A Lamas
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, 1900 La Plata, Argentina
| | - Fernanda Carrizo Velasquez
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, 1900 La Plata, Argentina
| | - Juan M Lofeudo
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, 1900 La Plata, Argentina
| | - Enrique L Portiansky
- Laboratorio de Análisis de Imágenes, Facultad de Ciencias Veterinarias, UNLP, Argentina; Established Investigators of CONICET, Argentina
| | - Bernardo V Alvarez
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, 1900 La Plata, Argentina; Established Investigators of CONICET, Argentina.
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19
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Seidler U, Nikolovska K. Slc26 Family of Anion Transporters in the Gastrointestinal Tract: Expression, Function, Regulation, and Role in Disease. Compr Physiol 2019; 9:839-872. [DOI: 10.1002/cphy.c180027] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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20
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Wong KY, McKay R, Liu Y, Towle K, Elloumi Y, Li X, Quan S, Dutta D, Sykes BD, Fliegel L. Diverse residues of intracellular loop 5 of the Na +/H + exchanger modulate proton sensing, expression, activity and targeting. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:191-200. [PMID: 30071192 DOI: 10.1016/j.bbamem.2018.07.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 07/26/2018] [Accepted: 07/27/2018] [Indexed: 10/28/2022]
Abstract
The mammalian Na+/H+ exchanger isoform 1 (NHE1) is an integral membrane protein that regulates intracellular pH (pHi) by removing a single intracellular proton in exchange for one extracellular sodium ion. It is involved in cardiac hypertrophy and ischemia reperfusion damage to the heart and elevation of its activity is a trigger for breast cancer metastasis. NHE1 has an extensive 500 amino acid N-terminal membrane domain that mediates transport and consists of 12 transmembrane segments connected by intracellular and extracellular loops. Intracellular loops are hypothesized to modulate the sensitivity to pHi. In this study, we characterized the structure and function of intracellular loop 5 (IL5), specifically amino acids 431-443. Mutation of eleven residues to alanine caused partial or nearly complete inhibition of transport; notably, mutation of residues L432, T433, I436, N437, R440 and K443 demonstrated these residues had critical roles in NHE1 function independent of effects on targeting or expression. The nuclear magnetic resonance (NMR) solution spectra of the IL5 peptide in a membrane mimetic sodium dodecyl sulfate solution revealed that IL5 has a stable three-dimensional structure with substantial alpha helical character. NMR chemical shifts indicated that K438 was in close proximity with W434. Overall, our results show that IL5 is a critical, intracellular loop with a propensity to form an alpha helix, and many residues of this intracellular loop are critical to proton sensing and ion transport.
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Affiliation(s)
- Ka Yee Wong
- Dept of Biochemistry, University of Alberta, Canada
| | - Ryan McKay
- Dept of Chemistry, University of Alberta, Canada.
| | | | | | | | - Xiuju Li
- Dept of Biochemistry, University of Alberta, Canada
| | - Sicheng Quan
- Dept of Biochemistry, University of Alberta, Canada
| | | | | | - Larry Fliegel
- Dept of Biochemistry, University of Alberta, Canada.
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21
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Noor SI, Jamali S, Ames S, Langer S, Deitmer JW, Becker HM. A surface proton antenna in carbonic anhydrase II supports lactate transport in cancer cells. eLife 2018; 7:35176. [PMID: 29809145 PMCID: PMC5986270 DOI: 10.7554/elife.35176] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 05/17/2018] [Indexed: 01/08/2023] Open
Abstract
Many tumor cells produce vast amounts of lactate and acid, which have to be removed from the cell to prevent intracellular lactacidosis and suffocation of metabolism. In the present study, we show that proton-driven lactate flux is enhanced by the intracellular carbonic anhydrase CAII, which is colocalized with the monocarboxylate transporter MCT1 in MCF-7 breast cancer cells. Co-expression of MCTs with various CAII mutants in Xenopus oocytes demonstrated that CAII facilitates MCT transport activity in a process involving CAII-Glu69 and CAII-Asp72, which could function as surface proton antennae for the enzyme. CAII-Glu69 and CAII-Asp72 seem to mediate proton transfer between enzyme and transporter, but CAII-His64, the central residue of the enzyme's intramolecular proton shuttle, is not involved in proton shuttling between the two proteins. Instead, this residue mediates binding between MCT and CAII. Taken together, the results suggest that CAII features a moiety that exclusively mediates proton exchange with the MCT to facilitate transport activity.
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Affiliation(s)
- Sina Ibne Noor
- Division of General Zoology, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Somayeh Jamali
- Division of General Zoology, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Samantha Ames
- Division of General Zoology, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Silke Langer
- Division of General Zoology, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Joachim W Deitmer
- Division of General Zoology, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Holger M Becker
- Division of General Zoology, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany.,Institute of Physiological Chemistry, University of Veterinary Medicine Hannover, Hannover, Germany
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22
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Ciocci Pardo A, Díaz RG, González Arbeláez LF, Pérez NG, Swenson ER, Mosca SM, Alvarez BV. Benzolamide perpetuates acidic conditions during reperfusion and reduces myocardial ischemia-reperfusion injury. J Appl Physiol (1985) 2017; 125:340-352. [PMID: 29357509 DOI: 10.1152/japplphysiol.00957.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
During ischemia, increased anaerobic glycolysis results in intracellular acidosis. Activation of alkalinizing transport mechanisms associated with carbonic anhydrases (CAs) leads to myocardial intracellular Ca2+ increase. We characterize the effects of inhibition of CA with benzolamide (BZ) during cardiac ischemia-reperfusion (I/R). Langendorff-perfused isolated rat hearts were subjected to 30 min of global ischemia and 60 min of reperfusion. Other hearts were treated with BZ (5 μM) during the initial 10 min of reperfusion or perfused with acid solution (AR, pH 6.4) during the first 3 min of reperfusion. p38MAPK, a kinase linked to membrane transporters and involved in cardioprotection, was examined in hearts treated with BZ in presence of the p38MAPK inhibitor SB202190 (10 μM). Infarct size (IZ) and myocardial function were assessed, and phosphorylated forms of p38MAPK, Akt, and PKCε were evaluated by immunoblotting. We determined the rate of intracellular pH (pHi) normalization after transient acid loading in the absence and presence of BZ or BZ + SB202190 in heart papillary muscles (HPMs). Mitochondrial membrane potential (ΔΨm), Ca2+ retention capacity and Ca2+-mediated swelling after I/R were also measured. BZ, similarly to AR, reduced IZ, improved postischemic recovery of myocardial contractility, increased phosphorylation of Akt, PKCε, and p38MAPK, and normalized ΔΨm and Ca2+ homeostasis, effects abolished after p38MAPK inhibition. In HPMs, BZ slowed pHi recovery, an effect that was restored after p38MAPK inhibition. We conclude that prolongation of acidic conditions during reperfusion by BZ could be responsible for the cardioprotective benefits of reduced infarction and better myocontractile function, through p38MAPK-dependent pathways. NEW & NOTEWORTHY Carbonic anhydrase inhibition by benzolamide (BZ) maintains acidity, decreases infarct size, and improves postischemic myocardial dysfunction in ischemia-reperfusion (I/R) hearts. Protection afforded by BZ mimicked the beneficial effects elicited by an acidic solution (AR). Increased phosphorylation of p38MAPK occurs in I/R hearts reperfused with BZ or with AR. Mitochondria from I/R hearts possess abnormal Ca2+ handling and a more depolarized membrane potential compared with control hearts, and these changes were restored by treatment with BZ or AR.
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Affiliation(s)
- Alejandro Ciocci Pardo
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata , La Plata , Argentina
| | - Romina G Díaz
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata , La Plata , Argentina
| | - Luisa F González Arbeláez
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata , La Plata , Argentina
| | - Néstor G Pérez
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata , La Plata , Argentina
| | - Erik R Swenson
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Washington, Department of Veterans Affairs Puget Sound Health Care System , Seattle, Washington
| | - Susana M Mosca
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata , La Plata , Argentina
| | - Bernardo V Alvarez
- Centro de Investigaciones Cardiovasculares CIC-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de La Plata , La Plata , Argentina
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Matteucci E, Giampietro O. Electron Pathways through Erythrocyte Plasma Membrane in Human Physiology and Pathology: Potential Redox Biomarker? Biomark Insights 2017. [DOI: 10.1177/117727190700200026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Erythrocytes are involved in the transport of oxygen and carbon dioxide in the body. Since pH is the influential factor in the Bohr-Haldane effect, pHi is actively maintained via secondary active transports Na+/H+ exchange and HC3–/Cl– anion exchanger. Because of the redox properties of the iron, hemoglobin generates reactive oxygen species and thus, the human erythrocyte is constantly exposed to oxidative damage. Although the adult erythrocyte lacks protein synthesis and cannot restore damaged proteins, it is equipped with high activity of protective enzymes. Redox changes in the cell initiate various signalling pathways. Plasma membrane oxido-reductases (PMORs) are trans-membrane electron transport systems that have been found in the membranes of all cells and have been extensively characterized in the human erythrocyte. Erythrocyte PMORs transfer reducing equivalents from intracellular reductants to extracellular oxidants, thus their most important role seems to be to enable the cell respond to changes in intra- and extra-cellular redox environments. So far the activity of erythrocyte PMORs in disease states has not been systematically investigated. This review summarizes present knowledge on erythrocyte electron transfer activity in humans (health, type 1 diabetes, diabetic nephropathy, and chronic uremia) and hypothesizes an integrated model of the functional organization of erythrocyte plasma membrane where electron pathways work in parallel with transport metabolons to maintain redox homeostasis.
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Affiliation(s)
- Elena Matteucci
- Department of Internal Medicine, University of Pisa, Pisa, Italy
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24
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Protein mediated regulation of the NHE1 isoform of the Na + /H + exchanger in renal cells. A regulatory role of Hsp90 and AKT kinase. Cell Signal 2017; 36:145-153. [DOI: 10.1016/j.cellsig.2017.05.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 04/28/2017] [Accepted: 05/05/2017] [Indexed: 11/19/2022]
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25
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Asgharzadeh MR, Barar J, Pourseif MM, Eskandani M, Jafari Niya M, Mashayekhi MR, Omidi Y. Molecular machineries of pH dysregulation in tumor microenvironment: potential targets for cancer therapy. BIOIMPACTS : BI 2017; 7:115-133. [PMID: 28752076 PMCID: PMC5524986 DOI: 10.15171/bi.2017.15] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/28/2017] [Accepted: 06/06/2017] [Indexed: 12/30/2022]
Abstract
Introduction: Cancer is an intricate disorder/dysfunction of cells that can be defined as a genetic heterogeneity in human disease. Therefore, it is characterized by several adaptive complex hallmarks. Among them, the pH dysregulation appears as a symbol of aberrant functions within the tumor microenvironment (TME). In comparison with normal tissues, in the solid tumors, we face with an irregular acidification and alkalinization of the extracellular and intracellular fluids. Methods: In this study, we comprehensively discussed the most recent reports on the hallmarks of solid tumors to provide deep insights upon the molecular machineries involved in the pH dysregulation of solid tumors and their impacts on the initiation and progression of cancer. Results: The dysregulation of pH in solid tumors is fundamentally related to the Warburg effect and hypoxia, leading to expression of a number of molecular machineries, including: NHE1, H+ pump V-ATPase, CA-9, CA-12, MCT-1, GLUT-1. Activation of proton exchangers and transporters (PETs) gives rise to formation of TME. This condition favors the cancer cells to evade from the anoikis and apoptosis, granting them aggressive and metastasis phenotype, as well as resistance to chemotherapy and radiation therapy. This review aimed to discuss the key molecular changes of tumor cells in terms of bio-energetics and cancer metabolism in relation with pH dysregulation. During this phenomenon, the intra- and extracellular metabolites are altered and/or disrupted. Such molecular alterations provide molecular hallmarks for direct targeting of the PETs by potent relevant inhibitors in combination with conventional cancer therapies as ultimate therapy against solid tumors. Conclusion: Taken all, along with other treatment strategies, targeting the key molecular machineries related to intra- and extracellular metabolisms within the TME is proposed as a novel strategy to inhibit or block PETs that are involved in the pH dysregulation of solid tumors.
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Affiliation(s)
- Mohammad Reza Asgharzadeh
- Department of Biology, Fars Science and Research Branch, Islamic Azad University, Marvdasht, Iran
- Department of Biology, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran
| | - Jaleh Barar
- Research Center for Pharmaceutical Nanotechnology, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Pharmaceutics, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohammad M. Pourseif
- Research Center for Pharmaceutical Nanotechnology, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Morteza Eskandani
- Research Center for Pharmaceutical Nanotechnology, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mojtaba Jafari Niya
- Department of Biology, Fars Science and Research Branch, Islamic Azad University, Marvdasht, Iran
- Department of Biology, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran
| | | | - Yadollah Omidi
- Research Center for Pharmaceutical Nanotechnology, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Pharmaceutics, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
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26
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Groszmann M, Osborn HL, Evans JR. Carbon dioxide and water transport through plant aquaporins. PLANT, CELL & ENVIRONMENT 2017; 40:938-961. [PMID: 27739588 DOI: 10.1111/pce.12844] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 09/01/2016] [Accepted: 09/22/2016] [Indexed: 05/25/2023]
Abstract
Aquaporins are channel proteins that function to increase the permeability of biological membranes. In plants, aquaporins are encoded by multigene families that have undergone substantial diversification in land plants. The plasma membrane intrinsic proteins (PIPs) subfamily of aquaporins is of particular interest given their potential to improve plant water relations and photosynthesis. Flowering plants have between 7 and 28 PIP genes. Their expression varies with tissue and cell type, through development and in response to a variety of factors, contributing to the dynamic and tissue specific control of permeability. There are a growing number of PIPs shown to act as water channels, but those altering membrane permeability to CO2 are more limited. The structural basis for selective substrate specificities has not yet been resolved, although a few key amino acid positions have been identified. Several regions important for dimerization, gating and trafficking are also known. PIP aquaporins assemble as tetramers and their properties depend on the monomeric composition. PIPs control water flux into and out of veins and stomatal guard cells and also increase membrane permeability to CO2 in mesophyll and stomatal guard cells. The latter increases the effectiveness of Rubisco and can potentially influence transpiration efficiency.
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Affiliation(s)
- Michael Groszmann
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
| | - Hannah L Osborn
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
| | - John R Evans
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
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Hendus-Altenburger R, Lambrughi M, Terkelsen T, Pedersen SF, Papaleo E, Lindorff-Larsen K, Kragelund BB. A phosphorylation-motif for tuneable helix stabilisation in intrinsically disordered proteins - Lessons from the sodium proton exchanger 1 (NHE1). Cell Signal 2017; 37:40-51. [PMID: 28554535 DOI: 10.1016/j.cellsig.2017.05.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 05/24/2017] [Accepted: 05/25/2017] [Indexed: 11/26/2022]
Abstract
Intrinsically disordered proteins (IDPs) are involved in many pivotal cellular processes including phosphorylation and signalling. The structural and functional effects of phosphorylation of IDPs remain poorly understood and difficult to predict. Thus, a need exists to identify motifs that confer phosphorylation-dependent perturbation of the local preferences for forming e.g. helical structures as well as motifs that do not. The disordered distal tail of the Na+/H+ exchanger 1 (NHE1) is six-times phosphorylated (S693, S723, S726, S771, T779, S785) by the mitogen activated protein kinase 2 (MAPK1, ERK2). Using NMR spectroscopy, we found that two out of those six phosphorylation sites had a stabilizing effect on transient helices. One of these was further investigated by circular dichroism and NMR spectroscopy as well as by molecular dynamic simulations, which confirmed the stabilizing effect and resulted in the identification of a short linear motif for helix stabilisation: [S/T]-P-{3}-[R/K] where [S/T] is the phosphorylation-site. By analysing IDP and phosphorylation site databases we found that the motif is significantly enriched around known phosphorylation sites, supporting a potential wider-spread role in phosphorylation-mediated regulation of intrinsically disordered proteins. The identification of such motifs is important for understanding the molecular mechanism of cellular signalling, and is crucial for the development of predictors for the structural effect of phosphorylation; a tool of relevance for understanding disease-promoting mutations that for example interfere with signalling for instance through constitutive active and often cancer-promoting signalling.
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Affiliation(s)
- Ruth Hendus-Altenburger
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| | - Matteo Lambrughi
- Computational Biology Laboratory, Center for Autophagy, Recycling and Disease, Strandboulevarden 49, 2100 Copenhagen, Denmark.
| | - Thilde Terkelsen
- Computational Biology Laboratory, Center for Autophagy, Recycling and Disease, Strandboulevarden 49, 2100 Copenhagen, Denmark.
| | - Stine F Pedersen
- Cell Biology and Physiology, Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark.
| | - Elena Papaleo
- Computational Biology Laboratory, Center for Autophagy, Recycling and Disease, Strandboulevarden 49, 2100 Copenhagen, Denmark.
| | - Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory, Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
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28
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Noor SI, Pouyssegur J, Deitmer JW, Becker HM. Integration of a 'proton antenna' facilitates transport activity of the monocarboxylate transporter MCT4. FEBS J 2016; 284:149-162. [PMID: 27860283 DOI: 10.1111/febs.13964] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 09/20/2016] [Accepted: 11/11/2016] [Indexed: 12/22/2022]
Abstract
Monocarboxylate transporters (MCTs) mediate the proton-coupled transport of high-energy metabolites like lactate and pyruvate and are expressed in nearly every mammalian tissue. We have shown previously that transport activity of MCT4 is enhanced by carbonic anhydrase II (CAII), which has been suggested to function as a 'proton antenna' for the transporter. In the present study, we tested whether creation of an endogenous proton antenna by introduction of a cluster of histidine residues into the C-terminal tail of MCT4 (MCT4-6xHis) could facilitate MCT4 transport activity when heterologously expressed in Xenopus oocytes. Our results show that integration of six histidines into the C-terminal tail does indeed increase transport activity of MCT4 to the same extent as did coexpression of MCT4-WT with CAII. Transport activity of MCT4-6xHis could be further enhanced by coexpression with extracellular CAIV, but not with intracellular CAII. Injection of an antibody against the histidine cluster into MCT4-expressing oocytes decreased transport activity of MCT4-6xHis, while leaving activity of MCT4-WT unaltered. Taken together, these findings suggest that transport activity of the proton-coupled monocarboxylate transporter MCT4 can be facilitated by integration of an endogenous proton antenna into the transporter's C-terminal tail.
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Affiliation(s)
- Sina Ibne Noor
- Division of General Zoology, Department of Biology, University of Kaiserslautern, Germany
| | - Jacques Pouyssegur
- Centre Scientifique de Monaco (CSM), Monaco.,Institute for Research on Cancer & Aging (IRCAN), INSERM, Centre A. Lacassagne, CNRS, University of Nice-Sophia Antipolis, France
| | - Joachim W Deitmer
- Division of General Zoology, Department of Biology, University of Kaiserslautern, Germany
| | - Holger M Becker
- Division of General Zoology, Department of Biology, University of Kaiserslautern, Germany
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29
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Li X, Augustine A, Chen S, Fliegel L. Stop Codon Polymorphisms in the Human SLC9A1 Gene Disrupt or Compromise Na+/H+ Exchanger Function. PLoS One 2016; 11:e0162902. [PMID: 27636896 PMCID: PMC5026351 DOI: 10.1371/journal.pone.0162902] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 08/30/2016] [Indexed: 11/18/2022] Open
Abstract
The NHE1 isoform of the mammalian Na+/H+ exchanger is a ubiquitous plasma membrane protein that regulates intracellular pH in mammalian cells by removing one intracellular proton in exchange for one extracellular sodium. Deletion of the NHE1 gene (SLC9A1) affects the growth and motor ability of mice and humans but mutations and polymorphisms of the gene are only beginning to be characterized. NHE1 has a cytosolic C-terminal regulatory tail of approximately 315 amino acids and a 500 amino acid membrane domain. We examined the functional effects of three human stop codon mutations at amino acids 321, 449 and 735 in comparison with a mutant that had a shortened tail region (543 stop codon). The short mutants, 321, 449 and 543 stop codon mutant proteins, lost NHE1 activity and expression, and did not target to the plasma membrane. Protein for these short mutants was more rapidly degraded than the wild type and 735 ending proteins. The 735 terminating mutant, with the membrane domain and much of the cytosolic tail, had reduced protein expression and activity. The results demonstrate that early stop codon polymorphisms have significant and deleterious effects on the activity of the SLC9A1 protein product. The 735-NHE1 mutant, without the last 80 amino acids, had more minor defects. Surprisingly, retention of a proximal 43 amino acids adjacent to the membrane domain did little to maintain NHE1 expression, targeting and activity.
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Affiliation(s)
- Xiuju Li
- Department of Biochemistry, University Alberta, Edmonton, AB T6G 2H7, Canada
| | - Aruna Augustine
- Department of Biochemistry, University Alberta, Edmonton, AB T6G 2H7, Canada
| | - Shuo Chen
- Department of Biochemistry, University Alberta, Edmonton, AB T6G 2H7, Canada
| | - Larry Fliegel
- Department of Biochemistry, University Alberta, Edmonton, AB T6G 2H7, Canada
- * E-mail:
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30
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Li X, Augustine A, Sun D, Li L, Fliegel L. Activation of the Na +/H + exchanger in isolated cardiomyocytes through β-Raf dependent pathways. Role of Thr 653 of the cytosolic tail. J Mol Cell Cardiol 2016; 99:65-75. [PMID: 27555478 DOI: 10.1016/j.yjmcc.2016.08.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 08/04/2016] [Accepted: 08/19/2016] [Indexed: 10/21/2022]
Abstract
The mammalian Na+/H+ exchanger isoform 1 (NHE1) is a ubiquitous plasma membrane protein that is a key regulator of intracellular pH in isolated cardiomyocytes. A 500 amino acid membrane domain removes protons and is regulated by a 315 amino acid cytosolic domain. In the myocardium, aberrant regulation of NHE1 contributes to ischemia reperfusion damage and to heart hypertrophy. We examined mechanisms of regulation of NHE1 in the myocardium by endothelin and β-Raf. Endothelin stimulated NHE1 activity and activated Erk-dependent pathways. Inhibition of β-Raf reduced NHE1 activity and Erk-pathway activation. We demonstrated that myocardial β-Raf binds to the C-terminal 182 amino acids of the NHE1 protein and that β-Raf is associated with NHE1 in intact cardiomyocytes. NHE1 was phosphorylated in vivo and the protein kinase inhibitor sorafenib reduced NHE1 phosphorylation levels. Immunoprecipitates of β-Raf from cardiomyocytes phosphorylated the C-terminal 182 amino acids of NHE1 and mass spectrometry analysis showed that amino acid Thr653 was phosphorylated. Mutation of this amino acid to Ala resulted in defective activity while mutation to Asp restored the activity. The results demonstrate that Thr653 is an important regulatory amino acid of NHE1 that is activated through β-Raf dependent pathways by phosphorylation either directly or indirectly by β-Raf, and this affects NHE1 activity.
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Affiliation(s)
- Xiuju Li
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
| | - Aruna Augustine
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
| | - Difei Sun
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada.
| | - Liang Li
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada.
| | - Larry Fliegel
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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31
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Mohamed IA, Mraiche F. Targeting osteopontin, the silent partner of Na+/H+ exchanger isoform 1 in cardiac remodeling. J Cell Physiol 2015; 230:2006-18. [PMID: 25677682 DOI: 10.1002/jcp.24958] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 02/06/2015] [Indexed: 12/11/2022]
Abstract
Cardiac hypertrophy (CH), characterized by the enlargement of cardiomyocytes, fibrosis and apoptosis, contributes to cardiac remodeling, which if left unresolved results in heart failure. Understanding the signaling pathways underlying CH is necessary to identify potential therapeutic targets. The Na(+) /H(+) -exchanger isoform I (NHE1), a ubiquitously expressed glycoprotein and cardiac specific isoform, regulates intracellular pH. Recent studies have demonstrated that enhanced expression/activity of NHE1 contributes to cardiac remodeling and CH. Inhibition of NHE1 in both in vitro and in vivo models have suggested that inhibition of NHE1 protects against hypertrophy. However, clinical trials using NHE1 inhibitors have proven to be unsuccessful, suggesting that additional factors maybe contributing to cardiac remodeling. Recent studies have indicated that the upregulation of NHE1 is associated with enhanced levels of osteopontin (OPN) in the setting of CH. OPN has been demonstrated to be upregulated in left ventricular hypertrophy, dilated cardiomyopathy and in diabetic cardiomyopathy. The cellular interplay between OPN and NHE1 in the setting of CH remains unknown. This review focuses on the role of NHE1 and OPN in cardiac remodeling and emphasizes the signaling pathways implicating OPN in the NHE1-induced hypertrophic response.
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32
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Abstract
The H(+) concentration in human blood is kept within very narrow limits, ~40 nmol/L, despite the fact that dietary metabolism generates acid and base loads that are added to the systemic circulation throughout the life of mammals. One of the primary functions of the kidney is to maintain the constancy of systemic acid-base chemistry. The kidney has evolved the capacity to regulate blood acidity by performing three key functions: (i) reabsorb HCO3(-) that is filtered through the glomeruli to prevent its excretion in the urine; (ii) generate a sufficient quantity of new HCO3(-) to compensate for the loss of HCO3(-) resulting from dietary metabolic H(+) loads and loss of HCO3(-) in the urea cycle; and (iii) excrete HCO3(-) (or metabolizable organic anions) following a systemic base load. The ability of the kidney to perform these functions requires that various cell types throughout the nephron respond to changes in acid-base chemistry by modulating specific ion transport and/or metabolic processes in a coordinated fashion such that the urine and renal vein chemistry is altered appropriately. The purpose of the article is to provide the interested reader with a broad review of a field that began historically ~60 years ago with whole animal studies, and has evolved to where we are currently addressing questions related to kidney acid-base regulation at the single protein structure/function level.
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Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, Los Angeles, CA; Brain Research Institute, UCLA, Los Angeles, CA
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33
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Carre G, Ouedraogo M, Magaud C, Carreyre H, Becq F, Bois P, Supuran CT, Thibaudeau S, Vandebrouck C, Bescond J. Vasorelaxation induced by dodoneine is mediated by calcium channels blockade and carbonic anhydrase inhibition on vascular smooth muscle cells. JOURNAL OF ETHNOPHARMACOLOGY 2015; 169:8-17. [PMID: 25847623 DOI: 10.1016/j.jep.2015.03.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 03/05/2015] [Accepted: 03/12/2015] [Indexed: 06/04/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Dodoneine (Ddn) is one of the active compounds identified from Agelanthus dodoneifolius (DC.) Polhill and Wiens, a medicinal plant used in traditional medicine for the treatment of hypertension. This dihydropyranone exerts hypotensive and vasorelaxant effects on rats, and two molecular targets have been characterized: the carbonic anhydrase and the L-type calcium channel in cardiomyocytes with biochemical and electrophysiological techniques, respectively. To further evaluate the involvement of these two molecular targets in vasorelaxation, the effect of Ddn on rat vascular smooth muscle was investigated. MATERIAL AND METHODS The effects of Ddn on L-type calcium current and on resting membrane potential were characterized in A7r5 cell line using the whole-cell patch-clamp configuration. The molecular identities of carbonic anhydrase isozymes in smooth muscle cells were examined with RT-PCR. Vascular response was measured on rat aortic rings in an organ bath apparatus and the effect of Ddn on intracellular pH was determined by flow cytometry using the pH-sensitive fluorescent probe BCECF-AM [2,7-Bis-(2-Carboxyethyl)-5-(and-6)-Carboxyfluorescein, Acetoxymethyl Ester]. RESULTS 100µM Ddn reduced calcium current density of about 30%. In addition, carbonic anhydrase II, III, XIII and XIV were shown to be expressed in rat aorta and inhibited in smooth muscle cells by Ddn. This inhibition resulted in a rise in pHi of about 0.31, leading to KCa channel activation, thereby inducing membrane hyperpolarization and vasorelaxation. The results of vascular reactivity experiments obtained with pharmacological tools acting on the L-type calcium current and carbonic anhydrase suggest that Ddn produces its vasorelaxant effect via the inhibition of these two molecular targets. CONCLUSION This study demonstrates that Ddn induced vasorelaxation by targeting two proteins involved in the modulation of excitation-contraction coupling: L-type calcium channels and carbonic anhydrase.
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Affiliation(s)
- Grégoire Carre
- Signalisation et Transports Ioniques Membranaires, Université de Poitiers, CNRS ERL 7368; 1 rue Georges Bonnet F-86073 Poitiers Cedex 09, France
| | - Maurice Ouedraogo
- Laboratoire de Physiologie Animale, Université de Ouagadougou, 03 BP 7021, Ouagadougou 01, Burkina Faso
| | - Christophe Magaud
- Signalisation et Transports Ioniques Membranaires, Université de Poitiers, CNRS ERL 7368; 1 rue Georges Bonnet F-86073 Poitiers Cedex 09, France
| | - Hélène Carreyre
- Superacid group in "Organic Synthesis" team, Université de Poitiers, CNRS UMR 7285 IC2MP, 4 avenue Michel Brunet, Poitiers 86022 Cedex, France
| | - Frédéric Becq
- Signalisation et Transports Ioniques Membranaires, Université de Poitiers, CNRS ERL 7368; 1 rue Georges Bonnet F-86073 Poitiers Cedex 09, France
| | - Patrick Bois
- Signalisation et Transports Ioniques Membranaires, Université de Poitiers, CNRS ERL 7368; 1 rue Georges Bonnet F-86073 Poitiers Cedex 09, France
| | - Claudiu T Supuran
- Università degli Studi di Firenze, Laboratorio di Chimica Bioinorganica, Rm 188, Via della Lastruccia 3, I-50019 Sesto Fiorentino (Firenze), Italy
| | - Sébastien Thibaudeau
- Superacid group in "Organic Synthesis" team, Université de Poitiers, CNRS UMR 7285 IC2MP, 4 avenue Michel Brunet, Poitiers 86022 Cedex, France
| | - Clarisse Vandebrouck
- Signalisation et Transports Ioniques Membranaires, Université de Poitiers, CNRS ERL 7368; 1 rue Georges Bonnet F-86073 Poitiers Cedex 09, France
| | - Jocelyn Bescond
- Signalisation et Transports Ioniques Membranaires, Université de Poitiers, CNRS ERL 7368; 1 rue Georges Bonnet F-86073 Poitiers Cedex 09, France.
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Krishnan D, Liu L, Wiebe SA, Casey JR, Cordat E, Alexander RT. Carbonic anhydrase II binds to and increases the activity of the epithelial sodium-proton exchanger, NHE3. Am J Physiol Renal Physiol 2015; 309:F383-92. [PMID: 26041446 DOI: 10.1152/ajprenal.00464.2014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 05/20/2015] [Indexed: 02/08/2023] Open
Abstract
Two-thirds of sodium filtered by the renal glomerulus is reabsorbed from the proximal tubule via a sodium/proton exchanger isoform 3 (NHE3)-dependent mechanism. Since sodium and bicarbonate reabsorption are coupled, we postulated that the molecules involved in their reabsorption [NHE3 and carbonic anhydrase II (CAII)] might physically and functionally interact. Consistent with this, CAII and NHE3 were closely associated in a renal proximal tubular cell culture model as revealed by a proximity ligation assay. Direct physical interaction was confirmed in solid-phase binding assays with immobilized CAII and C-terminal NHE3 glutathione-S-transferase fusion constructs. To assess the effect of CAII on NHE3 function, we expressed NHE3 in a proximal tubule cell line and measured NHE3 activity as the rate of intracellular pH recovery, following an acid load. NHE3-expressing cells had a significantly greater rate of intracellular pH recovery than controls. Inhibition of endogenous CAII activity with acetazolamide significantly decreased NHE3 activity, indicating that CAII activates NHE3. To ascertain whether CAII binding per se activates NHE3, we expressed NHE3 with wild-type CAII, a catalytically inactive CAII mutant (CAII-V143Y), or a mutant unable to bind other transporters (CAII-HEX). NHE3 activity increased upon wild-type CAII coexpression, but not in the presence of the CAII V143Y or HEX mutant. Together these studies support an association between CAII and NHE3 that alters the transporter's activity.
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Affiliation(s)
- Devishree Krishnan
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada; and
| | - Lei Liu
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Shane A Wiebe
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada; and
| | - Joseph R Casey
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada; Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada; and
| | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada; and
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada; and Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
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35
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Zhou Y, Mokhtari RB, Pan J, Cutz E, Yeger H. Carbonic anhydrase II mediates malignant behavior of pulmonary neuroendocrine tumors. Am J Respir Cell Mol Biol 2015; 52:183-92. [PMID: 25019941 DOI: 10.1165/rcmb.2014-0054oc] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
In normal lung, the predominant cytoplasmic carbonic anhydrase (CA) isozyme (CAII) is highly expressed in amine- and peptide-producing pulmonary neuroendocrine cells where its role involves CO2 sensing. Here, we report robust cytoplasmic expression of CAII by immunohistochemistry in the tumor cells of different native neuroendocrine tumor (NET) types, including typical and atypical carcinoids and small-cell lung carcinomas, and in NET and non-NET tumor cell lines. Because, in both pulmonary neuroendocrine cell and related NETs, the hypercapnia-induced secretion of bioactive serotonin (5-hydroxytryptamine) is mediated by CAII, we investigated the role of CAII in the biological behavior of carcinoid cell line H727 and the type II cell-derived A549 using both in vitro clonogenicity and in vivo xenograft model. We show that short hairpin RNA-mediated down-regulation of CAII resulted in significant reduction in clonogenicity of H727 and A549 cells in vitro, and marked suppression of tumor growth in vivo. CAII-short hairpin RNA cell-derived xenografts showed significantly reduced mitosis (phosphohistone H3 marker) and proliferation associated antigen Ki-67 (Ki67 marker), and significantly increased apoptosis by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Using an apoptosis gene array, we found no association with caspases 3 and 8, but with a novel association of CAII-mediated apoptosis with specific mitochondrial apoptosis-associated proteins. Furthermore, these xenografts showed a significantly reduced vascularization (CD31 marker). Thus, CAII may play a critical role in NET lung tumor growth, angiogenesis, and survival, possibly via 5-hydroxytryptamine, known to drive autocrine tumor growth. As such, CAII is a potential therapeutic target for the difficult-to-treat lung NETs.
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Affiliation(s)
- Yuanxiang Zhou
- 1 Division of Pathology, Department of Paediatric Laboratory Medicine, and
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Vilas G, Krishnan D, Loganathan SK, Malhotra D, Liu L, Beggs MR, Gena P, Calamita G, Jung M, Zimmermann R, Tamma G, Casey JR, Alexander RT. Increased water flux induced by an aquaporin-1/carbonic anhydrase II interaction. Mol Biol Cell 2015; 26:1106-18. [PMID: 25609088 PMCID: PMC4357510 DOI: 10.1091/mbc.e14-03-0812] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Aquaporin-1 (AQP1) enables greatly enhanced water flux across plasma membranes. The cytosolic carboxy terminus of AQP1 has two acidic motifs homologous to known carbonic anhydrase II (CAII) binding sequences. CAII colocalizes with AQP1 in the renal proximal tubule. Expression of AQP1 with CAII in Xenopus oocytes or mammalian cells increased water flux relative to AQP1 expression alone. This required the amino-terminal sequence of CAII, a region that binds other transport proteins. Expression of catalytically inactive CAII failed to increase water flux through AQP1. Proximity ligation assays revealed close association of CAII and AQP1, an effect requiring the second acidic cluster of AQP1. This motif was also necessary for CAII to increase AQP1-mediated water flux. Red blood cell ghosts resealed with CAII demonstrated increased osmotic water permeability compared with ghosts resealed with albumin. Water flux across renal cortical membrane vesicles, measured by stopped-flow light scattering, was reduced in CAII-deficient mice compared with wild-type mice. These data are consistent with CAII increasing water conductance through AQP1 by a physical interaction between the two proteins.
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Affiliation(s)
- Gonzalo Vilas
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - Devishree Krishnan
- Department of Physiology, University of Alberta, Edmonton, AB T6G 1C9, Canada Membrane Protein Disease Research Group, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - Sampath Kumar Loganathan
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 1C9, Canada Membrane Protein Disease Research Group, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - Darpan Malhotra
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 1C9, Canada Membrane Protein Disease Research Group, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - Lei Liu
- Department of Physiology, University of Alberta, Edmonton, AB T6G 1C9, Canada Membrane Protein Disease Research Group, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - Megan Rachele Beggs
- Department of Physiology, University of Alberta, Edmonton, AB T6G 1C9, Canada Membrane Protein Disease Research Group, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - Patrizia Gena
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70121 Bari, Italy
| | - Giuseppe Calamita
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70121 Bari, Italy
| | - Martin Jung
- Department of Medical Biochemistry and Molecular Biology, Saarland University, D-66424 Homburg, Germany
| | - Richard Zimmermann
- Department of Medical Biochemistry and Molecular Biology, Saarland University, D-66424 Homburg, Germany
| | - Grazia Tamma
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70121 Bari, Italy
| | - Joseph Roman Casey
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 1C9, Canada Department of Physiology, University of Alberta, Edmonton, AB T6G 1C9, Canada Membrane Protein Disease Research Group, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - Robert Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB T6G 1C9, Canada Membrane Protein Disease Research Group, University of Alberta, Edmonton, AB T6G 1C9, Canada Department of Pediatrics, University of Alberta, Edmonton, AB T6G 1C9, Canada
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Noor SI, Dietz S, Heidtmann H, Boone CD, McKenna R, Deitmer JW, Becker HM. Analysis of the binding moiety mediating the interaction between monocarboxylate transporters and carbonic anhydrase II. J Biol Chem 2015; 290:4476-86. [PMID: 25561737 DOI: 10.1074/jbc.m114.624577] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proton-coupled monocarboxylate transporters (MCTs) mediate the exchange of high energy metabolites like lactate between different cells and tissues. We have reported previously that carbonic anhydrase II augments transport activity of MCT1 and MCT4 by a noncatalytic mechanism, while leaving transport activity of MCT2 unaltered. In the present study, we combined electrophysiological measurements in Xenopus oocytes and pulldown experiments to analyze the direct interaction between carbonic anhydrase II (CAII) and MCT1, MCT2, and MCT4, respectively. Transport activity of MCT2-WT, which lacks a putative CAII-binding site, is not augmented by CAII. However, introduction of a CAII-binding site into the C terminus of MCT2 resulted in CAII-mediated facilitation of MCT2 transport activity. Interestingly, introduction of three glutamic acid residues alone was not sufficient to establish a direct interaction between MCT2 and CAII, but the cluster had to be arranged in a fashion that allowed access to the binding moiety in CAII. We further demonstrate that functional interaction between MCT4 and CAII requires direct binding of the enzyme to the acidic cluster (431)EEE in the C terminus of MCT4 in a similar fashion as previously shown for binding of CAII to the cluster (489)EEE in the C terminus of MCT1. In CAII, binding to MCT1 and MCT4 is mediated by a histidine residue at position 64. Taken together, our results suggest that facilitation of MCT transport activity by CAII requires direct binding between histidine 64 in CAII and a cluster of glutamic acid residues in the C terminus of the transporter that has to be positioned in surroundings that allow access to CAII.
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Affiliation(s)
- Sina Ibne Noor
- From the Department of Biology, Division of Zoology/Membrane Transport and
| | - Steffen Dietz
- From the Department of Biology, Division of Zoology/Membrane Transport and
| | - Hella Heidtmann
- From the Department of Biology, Division of Zoology/Membrane Transport and the Department of Biology, Division of General Zoology, University of Kaiserslautern, D-67653 Kaiserslautern, Germany and
| | - Christopher D Boone
- the Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610
| | - Robert McKenna
- the Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610
| | - Joachim W Deitmer
- the Department of Biology, Division of General Zoology, University of Kaiserslautern, D-67653 Kaiserslautern, Germany and
| | - Holger M Becker
- From the Department of Biology, Division of Zoology/Membrane Transport and
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Li X, Ma Y, Fliegel L. Functional role of arginine 425 in the mammalian Na+/H+ exchanger. Biochem Cell Biol 2014; 92:541-6. [DOI: 10.1139/bcb-2014-0070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Na+/H+ exchanger isoform 1 (NHE1) is the principal plasma membrane Na+/H+ exchanger of mammalian cells and functions by exchanging one intracellular proton for one extracellular sodium ion. Critical transmembrane segments of Na+/H+ exchangers have discontinuous transmembrane helices, which result in a dipole within the membrane. Amino acid R425 has been suggested to play an important role in neutralizing one such helix dipole. To investigate this hypothesis, R425 was mutated to alanine, glutamine, histidine, or lysine and the mutant NHE1 proteins were expressed and characterized in NHE1-deficient cells. The R425A and R425E mutants exhibited complete loss of expression of mature, fully glycosylated NHE1, reduced expression overall, and greatly reduced cell surface targeting. The cell surface targeting, expression, and activity of the R425H and R425K mutant proteins were also impaired, though residual NHE1 activity remained. When reduced targeting and expression were accounted for, the R425H and R425K mutant proteins had activity similar to that of the wild-type protein. The results suggest that R425 is critical for NHE1 expression, targeting, and activity and that replacement with another basic residue can rescue activity. The findings are consistent with a role for R425 in both neutralizing a helix dipole and maintaining NHE1 structure and function.
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Affiliation(s)
- Xiuju Li
- Department of Biochemistry, University of Alberta, 347 Medical Sciences Building, Edmonton, AB T6G 2H7, Canada
| | - Yike Ma
- Department of Biochemistry, University of Alberta, 347 Medical Sciences Building, Edmonton, AB T6G 2H7, Canada
| | - Larry Fliegel
- Department of Biochemistry, University of Alberta, 347 Medical Sciences Building, Edmonton, AB T6G 2H7, Canada
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Odunewu-Aderibigbe A, Fliegel L. The Na+/H+exchanger and pH regulation in the heart. IUBMB Life 2014; 66:679-85. [DOI: 10.1002/iub.1323] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Accepted: 10/15/2014] [Indexed: 11/11/2022]
Affiliation(s)
| | - Larry Fliegel
- Department of Biochemistry; University of Alberta; Edmonton AB Canada
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Hulikova A, Aveyard N, Harris AL, Vaughan-Jones RD, Swietach P. Intracellular carbonic anhydrase activity sensitizes cancer cell pH signaling to dynamic changes in CO2 partial pressure. J Biol Chem 2014; 289:25418-30. [PMID: 25059669 PMCID: PMC4162147 DOI: 10.1074/jbc.m114.547844] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 07/21/2014] [Indexed: 12/11/2022] Open
Abstract
Carbonic anhydrase (CA) enzymes catalyze the chemical equilibration among CO2, HCO3(-) and H(+). Intracellular CA (CAi) isoforms are present in certain types of cancer, and growing evidence suggests that low levels correlate with disease severity. However, their physiological role remains unclear. Cancer cell CAi activity, measured as cytoplasmic CO2 hydration rate (kf), ranged from high in colorectal HCT116 (∼2 s(-1)), bladder RT112 and colorectal HT29, moderate in fibrosarcoma HT1080 to negligible (i.e. spontaneous kf = 0.18 s(-1)) in cervical HeLa and breast MDA-MB-468 cells. CAi activity in cells correlated with CAII immunoreactivity and enzymatic activity in membrane-free lysates, suggesting that soluble CAII is an important intracellular isoform. CAi catalysis was not obligatory for supporting acid extrusion by H(+) efflux or HCO3(-) influx, nor for maintaining intracellular pH (pHi) uniformity. However, in the absence of CAi activity, acid loading from a highly alkaline pHi was rate-limited by HCO3(-) supply from spontaneous CO2 hydration. In solid tumors, time-dependence of blood flow can result in fluctuations of CO2 partial pressure (pCO2) that disturb cytoplasmic CO2-HCO3(-)-H(+) equilibrium. In cancer cells with high CAi activity, extracellular pCO2 fluctuations evoked faster and larger pHi oscillations. Functionally, these resulted in larger pH-dependent intracellular [Ca(2+)] oscillations and stronger inhibition of the mTORC1 pathway reported by S6 kinase phosphorylation. In contrast, the pHi of cells with low CAi activity was less responsive to pCO2 fluctuations. Such low pass filtering would "buffer" cancer cell pHi from non-steady-state extracellular pCO2. Thus, CAi activity determines the coupling between pCO2 (a function of tumor perfusion) and pHi (a potent modulator of cancer cell physiology).
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Affiliation(s)
- Alzbeta Hulikova
- From the Department of Physiology, Anatomy and Genetics, Oxford University, Parks Road, Oxford OX1 3PT, United Kingdom and
| | - Nicholas Aveyard
- From the Department of Physiology, Anatomy and Genetics, Oxford University, Parks Road, Oxford OX1 3PT, United Kingdom and
| | - Adrian L Harris
- Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford University, Oxford OX3 9DS, United Kingdom
| | - Richard D Vaughan-Jones
- From the Department of Physiology, Anatomy and Genetics, Oxford University, Parks Road, Oxford OX1 3PT, United Kingdom and
| | - Pawel Swietach
- From the Department of Physiology, Anatomy and Genetics, Oxford University, Parks Road, Oxford OX1 3PT, United Kingdom and
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Sowah D, Brown BF, Quon A, Alvarez BV, Casey JR. Resistance to cardiomyocyte hypertrophy in ae3-/- mice, deficient in the AE3 Cl-/HCO3- exchanger. BMC Cardiovasc Disord 2014; 14:89. [PMID: 25047106 PMCID: PMC4120010 DOI: 10.1186/1471-2261-14-89] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 07/16/2014] [Indexed: 12/21/2022] Open
Abstract
Background Cardiac hypertrophy is central to the etiology of heart failure. Understanding the molecular pathways promoting cardiac hypertrophy may identify new targets for therapeutic intervention. Sodium-proton exchanger (NHE1) activity and expression levels in the heart are elevated in many models of hypertrophy through protein kinase C (PKC)/MAPK/ERK/p90RSK pathway stimulation. Sustained NHE1 activity, however, requires an acid-loading pathway. Evidence suggests that the Cl−/HCO3− exchanger, AE3, provides this acid load. Here we explored the role of AE3 in the hypertrophic growth cascade of cardiomyocytes. Methods AE3-deficient (ae3−/−) mice were compared to wildtype (WT) littermates to examine the role of AE3 protein in the development of cardiomyocyte hypertrophy. Mouse hearts were assessed by echocardiography. As well, responses of cultured cardiomyocytes to hypertrophic stimuli were measured. pH regulation capacity of ae3−/− and WT cardiomyocytes was assessed in cultured cells loaded with the pH-sensitive dye, BCECF-AM. Results ae3−/− mice were indistinguishable from wild type (WT) mice in terms of cardiovascular performance. Stimulation of ae3−/− cardiomyocytes with hypertrophic agonists did not increase cardiac growth or reactivate the fetal gene program. ae3−/− mice are thus protected from pro-hypertrophic stimulation. Steady state intracellular pH (pHi) in ae3−/− cardiomyocytes was not significantly different from WT, but the rate of recovery of pHi from imposed alkalosis was significantly slower in ae3−/− cardiomyocytes. Conclusions These data reveal the importance of AE3-mediated Cl−/HCO3− exchange in cardiovascular pH regulation and the development of cardiomyocyte hypertrophy. Pharmacological antagonism of AE3 is an attractive approach in the treatment of cardiac hypertrophy.
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Affiliation(s)
| | | | | | | | - Joseph R Casey
- Department of Biochemistry and Membrane Protein Disease Research Group, University of Alberta, Edmonton T6G 2H7, Canada.
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Reshkin SJ, Greco MR, Cardone RA. Role of pHi, and proton transporters in oncogene-driven neoplastic transformation. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130100. [PMID: 24493748 DOI: 10.1098/rstb.2013.0100] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The change of a normal, healthy cell to a transformed cell is the first step in the evolutionary arc of a cancer. While the role of oncogenes in this 'passage' is well known, the role of ion transporters in this critical step is less known and is fundamental to our understanding the early physiological processes of carcinogenesis. Cancer cells and tissues have an aberrant regulation of hydrogen ion dynamics leading to a reversal of the normal tissue intracellular to extracellular pH gradient (ΔpHi to ΔpHe). When this perturbation in pH dynamics occurs during carcinogenesis is less clear. Very early studies using the introduction of different oncogene proteins into cells observed a concordance between neoplastic transformation and a cytoplasmic alkalinization occurring concomitantly with a shift towards glycolysis in the presence of oxygen, i.e. 'Warburg metabolism'. These processes may instigate a vicious cycle that drives later progression towards fully developed cancer where the reversed pH gradient becomes ever more pronounced. This review presents our understanding of the role of pH and the NHE1 in driving transformation, in determining the first appearance of the cancer 'hallmark' characteristics and how the use of pharmacological approaches targeting pH/NHE1 may open up new avenues for efficient treatments even during the first steps of cancer development.
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Affiliation(s)
- Stephan Joel Reshkin
- Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, , Bari 70126, Italy
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Abstract
Carbonic anhydrases are ubiquitous enzymes that catalyze the reversible hydration of carbon dioxide. These enzymes are of ancient origin as they are found in the deepest of branches of the evolutionary tree. Of the five different classes of carbonic anhydrases, the alpha class has perhaps received the most attention because of its role in human pathology. This review focuses on the physiological function of this class of carbonic anhydrases organized by their cellular location.
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Affiliation(s)
- Susan C Frost
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA,
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Abstract
Carbonic anhydrases (CAs) have not only been identified as ubiquitous enzymes catalyzing the fast reversible hydration of carbon dioxide to generate or consume protons and bicarbonate, but also as intra- and extracellular proteins, which facilitate transport function of many acid/base transporting membrane proteins, coined 'transport metabolon'. Functional interaction between CAs and acid/base transporters, such as chloride/bicarbonate exchanger (AE), sodium-bicarbonate cotransporter (NBC) and sodium/hydrogen exchanger (NHE) has been shown to require both catalytic CA activity as well as direct binding of the enzyme to specific sites on the transporter. In contrast, functional interaction between different CA isoforms and lactate-proton-cotransporting monocarboxylate transporters (MCT) has been found to be isoform-specific and independent of CA catalytic activity, but seems to require an intramolecular proton shuttle within the enzyme. In this chapter, we review the various types of interactions between acid/base-coupled membrane carriers and different CA isoforms, as studied in vitro, in intact Xenopus oocytes, and in various mammalian cell types. Furthermore, we discuss recent findings that indicate the significance of these 'transport metabolons' for normal cell functions.
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Hendus-Altenburger R, Kragelund BB, Pedersen SF. Structural dynamics and regulation of the mammalian SLC9A family of Na⁺/H⁺ exchangers. CURRENT TOPICS IN MEMBRANES 2014; 73:69-148. [PMID: 24745981 DOI: 10.1016/b978-0-12-800223-0.00002-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mammalian Na⁺/H⁺ exchangers of the SLC9A family are widely expressed and involved in numerous essential physiological processes. Their primary function is to mediate the 1:1 exchange of Na⁺ for H⁺ across the membrane in which they reside, and they play central roles in regulation of body, cellular, and organellar pH. Their function is tightly regulated through mechanisms involving interactions with multiple protein and lipid-binding partners, phosphorylations, and other posttranslational modifications. Biochemical and mutational analyses indicate that the SLC9As have a short intracellular N-terminus, 12 transmembrane (TM) helices necessary and sufficient for ion transport, and a C-terminal cytoplasmic tail region with essential regulatory roles. No high-resolution structures of the SLC9As exist; however, models based on crystal structures of the bacterial NhaAs support the 12 TM organization and suggest that TMIV and XI may form a central part of the ion-translocation pathway, whereas pH sensing may involve TMII, TMIX, and several intracellular loops. Similar to most ion transporters studied, SLC9As likely exist as coupled dimers in the membrane, and this appears to be important for the well-studied cooperativity of H⁺ binding. The aim of this work is to summarize and critically discuss the currently available evidence on the structural dynamics, regulation, and binding partner interactions of SLC9As, focusing in particular on the most widely studied isoform, SLC9A1/NHE1. Further, novel bioinformatic and structural analyses are provided that to some extent challenge the existing paradigm on how ions are transported by mammalian SLC9As.
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Affiliation(s)
- Ruth Hendus-Altenburger
- Section for Biomolecular Sciences, Department of Biology, University of Copenhagen, Copenhagen, Denmark; Section for Cell and Developmental Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Birthe B Kragelund
- Section for Biomolecular Sciences, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Stine Falsig Pedersen
- Section for Cell and Developmental Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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Klier M, Andes FT, Deitmer JW, Becker HM. Intracellular and extracellular carbonic anhydrases cooperate non-enzymatically to enhance activity of monocarboxylate transporters. J Biol Chem 2013; 289:2765-75. [PMID: 24338019 DOI: 10.1074/jbc.m113.537043] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Proton-coupled monocarboxylate transporters (MCTs) are carriers of high-energy metabolites such as lactate, pyruvate, and ketone bodies and are expressed in most tissues. It has previously been shown that transport activity of MCT1 and MCT4 is enhanced by the cytosolic carbonic anhydrase II (CAII) independent of its catalytic activity. We have now studied the influence of the extracellular, membrane-bound CAIV on transport activity of MCT1/4, heterologously expressed in Xenopus oocytes. Coexpression of CAIV with MCT1 and MCT4 resulted in a significant increase in MCT transport activity, even in the nominal absence of CO2/HCO3(-). CAIV-mediated augmentation of MCT activity was independent of the CAIV catalytic function, since application of the CA-inhibitor ethoxyzolamide or coexpression of the catalytically inactive mutant CAIV-V165Y did not suppress CAIV-mediated augmentation of MCT transport activity. The interaction required CAIV at the extracellular surface, since injection of CAIV protein into the oocyte cytosol did not augment MCT transport function. The effects of cytosolic CAII (injected as protein) and extracellular CAIV (expressed) on MCT transport activity, were additive. Our results suggest that intra- and extracellular carbonic anhydrases can work in concert to ensure rapid shuttling of metabolites across the cell membrane.
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Affiliation(s)
- Michael Klier
- From the Division of General Zoology, Department of Biology, University of Kaiserslautern D-67653 Kaiserslautern, Germany and
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47
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Villafuerte FC, Swietach P, Youm JB, Ford K, Cardenas R, Supuran CT, Cobden PM, Rohling M, Vaughan-Jones RD. Facilitation by intracellular carbonic anhydrase of Na+ -HCO3- co-transport but not Na+ / H+ exchange activity in the mammalian ventricular myocyte. J Physiol 2013; 592:991-1007. [PMID: 24297849 PMCID: PMC3948559 DOI: 10.1113/jphysiol.2013.265439] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Carbonic anhydrase enzymes (CAs) catalyse the reversible hydration of CO2 to H+ and HCO3- ions. This catalysis is proposed to be harnessed by acid/base transporters, to facilitate their transmembrane flux activity, either through direct protein-protein binding (a 'transport metabolon') or local functional interaction. Flux facilitation has previously been investigated by heterologous co-expression of relevant proteins in host cell lines/oocytes. Here, we examine the influence of intrinsic CA activity on membrane HCO3- or H+ transport via the native acid-extruding proteins, Na+ -HCO3- cotransport (NBC) and Na+ / H+ exchange (NHE), expressed in enzymically isolated mammalian ventricular myocytes. Effects of intracellular and extracellular (exofacial) CA (CAi and CAe) are distinguished using membrane-permeant and -impermeant pharmacological CA inhibitors, while measuring transporter activity in the intact cell using pH and Na+ fluorophores. We find that NBC, but not NHE flux is enhanced by catalytic CA activity, with facilitation being confined to CAi activity alone. Results are quantitatively consistent with a model where CAi catalyses local H+ ion delivery to the NBC protein, assisting the subsequent (uncatalysed) protonation and removal of imported HCO3- ions. In well-superfused myocytes, exofacial CA activity is superfluous, most likely because extracellular CO2/HCO3- buffer is clamped at equilibrium. The CAi insensitivity of NHE flux suggests that, in the native cell, intrinsic mobile buffer-shuttles supply sufficient intracellular H+ ions to this transporter, while intrinsic buffer access to NBC proteins is restricted. Our results demonstrate a selective CA facilitation of acid/base transporters in the ventricular myocyte, implying a specific role for the intracellular enzyme in HCO3- transport, and hence pHi regulation in the heart.
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Affiliation(s)
- Francisco C Villafuerte
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK.
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Li X, Prins D, Michalak M, Fliegel L. Calmodulin-dependent binding to the NHE1 cytosolic tail mediates activation of the Na+/H+ exchanger by Ca2+ and endothelin. Am J Physiol Cell Physiol 2013; 305:C1161-9. [PMID: 24088894 DOI: 10.1152/ajpcell.00208.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The mammalian Na(+)/H(+) exchanger isoform 1 (NHE1) is a ubiquitous plasma membrane protein that regulates intracellular pH by removing a single proton (H(+)) in exchange for one extracellular Na(+). The human protein contains a ∼500-amino acid membrane domain and a regulatory, ∼315-amino acid cytosolic domain. NHE1 is activated by a number of hormones including endothelin (ET) and by Ca(2+). The regulatory tail possesses an inhibitory calmodulin (CaM)-binding domain, and inhibition of NHE1 is relieved by binding of a Ca(2+)-CaM complex. We examined the dynamics of ET-1 and Ca(2+) regulation of binding to NHE1 in vivo. CFP was linked to the NHE1 protein cytoplasmic COOH terminus. This was stably transfected into AP-1 cells that are devoid of their own NHE1 protein. The protein was expressed and targeted properly and retained NHE1 activity comparable to the wild-type protein. We examined the in vivo coupling of NHE1 to CaM by Förster resonance energy transfer using CaM linked to the fluorescent protein Venus. CaM interaction with NHE1 was dynamic. Removal of serum reduced CaM interaction with NHE1. Addition of the Ca(2+) ionophore ionomycin increased the interaction between CaM and NHE1. We expressed an ET receptor in AP-1 cells and also found a time-dependent association of NHE1 with CaM in vivo that was dependent on ET treatment. The results are the first demonstration of the in vivo association of NHE1 and CaM through ET-dependent signaling pathways.
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Affiliation(s)
- Xiuju Li
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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Vargas LA, Díaz RG, Swenson ER, Pérez NG, Álvarez BV. Inhibition of carbonic anhydrase prevents the Na(+)/H(+) exchanger 1-dependent slow force response to rat myocardial stretch. Am J Physiol Heart Circ Physiol 2013; 305:H228-37. [PMID: 23709596 DOI: 10.1152/ajpheart.00055.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Myocardial stretch is an established signal that leads to hypertrophy. Myocardial stretch induces a first immediate force increase followed by a slow force response (SFR), which is a consequence of an increased Ca(2+) transient that follows the NHE1 Na(+)/H(+) exchanger activation. Carbonic anhydrase II (CAII) binds to the extreme COOH terminus of NHE1 and regulates its transport activity. We aimed to test the role of CAII bound to NHE1 in the SFR. The SFR and changes in intracellular pH (pHi) were evaluated in rat papillary muscle bathed with CO2/HCO3(-) buffer and stretched from 92% to 98% of the muscle maximal force development length for 10 min in the presence of the CA inhibitor 6-ethoxzolamide (ETZ, 100 μM). SFR control was 120 ± 3% (n = 8) of the rapid initial phase and was fully blocked by ETZ (99 ± 4%, n = 6). The SFR corresponded to a maximal increase in pHi of 0.18 ± 0.02 pH units (n = 4), and pHi changes were blocked by ETZ (0.04 ± 0.04, n = 6), as monitored by epifluorescence. NHE1/CAII physical association was examined in the SFR by coimmunoprecipitation, using muscle lysates. CAII immunoprecipitated with an anti-NHE1 antibody and the CAII immunoprecipitated protein levels increased 58 ± 9% (n = 6) upon stretch of muscles, assessed by immunoblots. The p90(RSK) kinase inhibitor SL0101-1 (10 μM) blocked the SFR of heart muscles after stretch 102 ± 2% (n = 4) and reduced the binding of CAII to NHE1, suggesting that the stretch-induced phosphorylation of NHE1 increases its binding to CAII. CAII/NHE1 interaction constitutes a component of the SFR to heart muscle stretch, which potentiates NHE1-mediated H(+) transport in the myocardium.
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Affiliation(s)
- Lorena A Vargas
- Centro de Investigaciones Cardiovasculares, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
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Provost JJ, Wallert MA. Inside out: targeting NHE1 as an intracellular and extracellular regulator of cancer progression. Chem Biol Drug Des 2013; 81:85-101. [PMID: 23253131 DOI: 10.1111/cbdd.12035] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The sodium hydrogen exchanger isoform one is a critical regulator of intracellular pH, serves as an anchor for the formation of cytoplasmic signaling complexes, and modulates cytoskeletal organization. There is a growing interest in the potential for sodium hydrogen exchanger isoform one as a therapeutic target against cancer. Sodium hydrogen exchanger isoform one transport drives formation of membrane protrusions essential for cell migration and contributes to the establishment of a tumor microenvironment that leads to the rearrangement of the extracellular matrix further supporting tumor progression. Here, we focus on the potential impact that an inexpensive, $100 genome would have in identifying prospective therapeutic targets to treat tumors based upon changes in gene expression and variation of sodium hydrogen exchanger isoform one regulators. In particular, we will focus on the ezrin, radixin, moesin family proteins, calcineurin B homologous proteins, Ras/Raf/MEK/ERK signaling, and phosphoinositide signaling as they relate to the regulation of sodium hydrogen exchanger isoform one in cancer progression.
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Affiliation(s)
- Joseph J Provost
- Center for Biopharmaceutical Research and Production, North Dakota State University, Fargo, ND 58102, USA.
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