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Rivera A, Vandorpe DH, Shmukler BE, Andolfo I, Iolascon A, Archer NM, Shabani E, Auerbach M, Hamerschlak N, Morton J, Wohlgemuth JG, Brugnara C, Snyder LM, Alper SL. Erythrocyte ion content and dehydration modulate maximal Gardos channel activity in KCNN4 V282M/+ hereditary xerocytosis red cells. Am J Physiol Cell Physiol 2019; 317:C287-C302. [PMID: 31091145 DOI: 10.1152/ajpcell.00074.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hereditary xerocytosis (HX) is caused by missense mutations in either the mechanosensitive cation channel PIEZO1 or the Ca2+-activated K+ channel KCNN4. All HX-associated KCNN4 mutants studied to date have revealed increased current magnitude and red cell dehydration. Baseline KCNN4 activity was increased in HX red cells heterozygous for KCNN4 mutant V282M. However, HX red cells maximally stimulated by Ca2+ ionophore A23187 or by PMCA Ca2+-ATPase inhibitor orthovanadate displayed paradoxically reduced KCNN4 activity. This reduced Ca2+-stimulated mutant KCNN4 activity in HX red cells was associated with unchanged sensitivity to KCNN4 inhibitor senicapoc and KCNN4 activator Ca2+, with slightly elevated Ca2+ uptake and reduced PMCA activity, and with decreased KCNN4 activation by calpain inhibitor PD150606. The altered intracellular monovalent cation content of HX red cells prompted experimental nystatin manipulation of red cell Na and K contents. Nystatin-mediated reduction of intracellular K+ with corresponding increase in intracellular Na+ in wild-type cells to mimic conditions of HX greatly suppressed vanadate-stimulated and A23187-stimulated KCNN4 activity in those wild-type cells. However, conferral of wild-type cation contents on HX red cells failed to restore wild-type-stimulated KCNN4 activity to those HX cells. The phenotype of reduced, maximally stimulated KCNN4 activity was shared by HX erythrocytes expressing heterozygous PIEZO1 mutants R2488Q and V598M, but not by HX erythrocytes expressing heterozygous KCNN4 mutant R352H or PIEZO1 mutant R2456H. Our data suggest that chronic KCNN4-driven red cell dehydration and intracellular cation imbalance can lead to reduced KCNN4 activity in HX and wild-type red cells.
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Affiliation(s)
- Alicia Rivera
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - David H Vandorpe
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Boris E Shmukler
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Immacolata Andolfo
- Department of Molecular Medicine and Medical Biotechnologies, "Federico II" University of Naples, CEINGE Biotecnologie Avanzate, Naples, Italy
| | - Achille Iolascon
- Department of Molecular Medicine and Medical Biotechnologies, "Federico II" University of Naples, CEINGE Biotecnologie Avanzate, Naples, Italy
| | - Natasha M Archer
- Division of Hematology and Oncology, Boston Children's Hospital, Dana-Farber Cancer Center, Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
| | - Estela Shabani
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
| | | | - Nelson Hamerschlak
- Department of Hematology, Hospital Israelita Albert Einstein, Sao Paulo, Brazil
| | - James Morton
- Quest Diagnostics, San Juan Capistrano, California
| | | | - Carlo Brugnara
- Department of Laboratory Medicine, Boston Children's Hospital and Department of Pathology, Harvard Medical School, Boston, Massachusetts
| | - L Michael Snyder
- Quest Diagnostics, Marlborough, Massachusetts.,Departments of Medicine and Laboratory Medicine, University of Massachusetts Medical Center, Worcester, Massachusetts
| | - Seth L Alper
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts
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Stewart AK, Shmukler BE, Vandorpe DH, Rivera A, Heneghan JF, Li X, Hsu A, Karpatkin M, O'Neill AF, Bauer DE, Heeney MM, John K, Kuypers FA, Gallagher PG, Lux SE, Brugnara C, Westhoff CM, Alper SL. Loss-of-function and gain-of-function phenotypes of stomatocytosis mutant RhAG F65S. Am J Physiol Cell Physiol 2011; 301:C1325-43. [PMID: 21849667 PMCID: PMC3233792 DOI: 10.1152/ajpcell.00054.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Accepted: 08/11/2011] [Indexed: 11/22/2022]
Abstract
Four patients with overhydrated cation leak stomatocytosis (OHSt) exhibited the heterozygous RhAG missense mutation F65S. OHSt erythrocytes were osmotically fragile, with elevated Na and decreased K contents and increased cation channel-like activity. Xenopus oocytes expressing wild-type RhAG and RhAG F65S exhibited increased ouabain and bumetanide-resistant uptake of Li(+) and (86)Rb(+), with secondarily increased (86)Rb(+) influx sensitive to ouabain and to bumetanide. Increased RhAG-associated (14)C-methylammonium (MA) influx was severely reduced in RhAG F65S-expressing oocytes. RhAG-associated influxes of Li(+), (86)Rb(+), and (14)C-MA were pharmacologically distinct, and Li(+) uptakes associated with RhAG and RhAG F65S were differentially inhibited by NH(4)(+) and Gd(3+). RhAG-expressing oocytes were acidified and depolarized by 5 mM bath NH(3)/NH(4)(+), but alkalinized and depolarized by subsequent bath exposure to 5 mM methylammonium chloride (MA/MA(+)). RhAG F65S-expressing oocytes exhibited near-wild-type responses to NH(4)Cl, but MA/MA(+) elicited attenuated alkalinization and strong hyperpolarization. Expression of RhAG or RhAG F65S increased steady-state cation currents unaltered by bath Li(+) substitution or bath addition of 5 mM NH(4)Cl or MA/MA(+). These oocyte studies suggest that 1) RhAG expression increases oocyte transport of NH(3)/NH(4)(+) and MA/MA(+); 2) RhAG F65S exhibits gain-of-function phenotypes of increased cation conductance/permeability, and loss-of-function phenotypes of decreased and modified MA/MA(+) transport, and decreased NH(3)/NH(4)(+)-associated depolarization; and 3) RhAG transports NH(3)/NH(4)(+) and MA/MA(+) by distinct mechanisms, and/or the substrates elicit distinct cellular responses. Thus, RhAG F65S is a loss-of-function mutation for amine transport. The altered oocyte intracellular pH, membrane potential, and currents associated with RhAG or RhAG F65S expression may reflect distinct transport mechanisms.
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Affiliation(s)
- Andrew K Stewart
- Beth Israel Deaconess Medical Center, 330 Brookline Ave., Boston, MA 02215, USA
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Almomani EY, Chu CY, Cordat E. Mis-trafficking of bicarbonate transporters: implications to human diseasesThis paper is one of a selection of papers published in a Special Issue entitled CSBMCB 53rd Annual Meeting — Membrane Proteins in Health and Disease, and has undergone the Journal’s usual peer review process. Biochem Cell Biol 2011; 89:157-77. [DOI: 10.1139/o10-153] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Bicarbonate is a waste product of mitochondrial respiration and one of the main buffers in the human body. Thus, bicarbonate transporters play an essential role in maintaining acid-base balance but also during fetal development as they ensure tight regulation of cytosolic and extracellular environments. Bicarbonate transporters belong to two gene families, SLC4A and SLC26A. Proteins from these two families are widely expressed, and thus mutations in their genes result in various diseases that affect bones, pancreas, reproduction, brain, kidneys, eyes, heart, thyroid, red blood cells, and lungs. In this minireview, we discuss the current state of knowledge regarding the effect of SLC4A and SLC26A mutants, with a special emphasis on mutants that have been studied in mammalian cell lines and how they correlate with phenotypes observed in mice models.
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Affiliation(s)
- Ensaf Y. Almomani
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Carmen Y.S. Chu
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Emmanuelle Cordat
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
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Swietach P, Tiffert T, Mauritz JMA, Seear R, Esposito A, Kaminski CF, Lew VL, Vaughan-Jones RD. Hydrogen ion dynamics in human red blood cells. J Physiol 2010; 588:4995-5014. [PMID: 20962000 DOI: 10.1113/jphysiol.2010.197392] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Our understanding of pH regulation within red blood cells (RBCs) has been inferred mainly from indirect experiments rather than from in situ measurements of intracellular pH (pH(i)). The present work shows that carboxy-SNARF-1, a pH fluorophore, when used with confocal imaging or flow cytometry, reliably reports pH(i) in individual, human RBCs, provided intracellular fluorescence is calibrated using a 'null-point' procedure. Mean pH(i) was 7.25 in CO(2)/HCO(3)(-)-buffered medium and 7.15 in Hepes-buffered medium, and varied linearly with extracellular pH (slope of 0.77). Intrinsic (non-CO(2)/HCO(3)(-)-dependent) buffering power, estimated in the intact cell (85 mmol (l cell)(-1) (pH unit)(-1) at resting pH(i)), was somewhat higher than previous estimates from cell lysates (50-70 mmol (l cell)(-1) (pH unit)(-1)). Acute displacement of pH(i) (superfusion of weak acids/bases) triggered rapid pH(i) recovery. This was mediated via membrane Cl(-)/HCO(3)(-) exchange (the AE1 gene product), irrespective of whether recovery was from an intracellular acid or base load, and with no evident contribution from other transporters such as Na(+)/H(+) exchange. H(+)-equivalent flux through AE1 was a linear function of [H(+)](i) and reversed at resting pH(i), indicating that its activity is not allosterically regulated by pH(i), in contrast to other AE isoforms. By simultaneously monitoring pH(i) and markers of cell volume, a functional link between membrane ion transport, volume and pH(i) was demonstrated. RBC pH(i) is therefore tightly regulated via AE1 activity, but modulated during changes of cell volume. A comparable volume-pH(i) link may also be important in other cell types expressing anion exchangers. Direct measurement of pH(i) should be useful in future investigations of RBC physiology and pathology.
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Affiliation(s)
- Pawel Swietach
- Department of Physiology, Burdon Sanderson Cardiac Science Centre, Parks Road, Oxford OX1 3PT, UK.
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van den Akker E, Satchwell TJ, Williamson RC, Toye AM. Band 3 multiprotein complexes in the red cell membrane; of mice and men. Blood Cells Mol Dis 2010; 45:1-8. [DOI: 10.1016/j.bcmd.2010.02.019] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Accepted: 02/04/2010] [Indexed: 02/02/2023]
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Vandorpe DH, Xu C, Shmukler BE, Otterbein LE, Trudel M, Sachs F, Gottlieb PA, Brugnara C, Alper SL. Hypoxia activates a Ca2+-permeable cation conductance sensitive to carbon monoxide and to GsMTx-4 in human and mouse sickle erythrocytes. PLoS One 2010; 5:e8732. [PMID: 20090940 PMCID: PMC2806905 DOI: 10.1371/journal.pone.0008732] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 12/18/2009] [Indexed: 01/23/2023] Open
Abstract
Background Deoxygenation of sickle erythrocytes activates a cation permeability of unknown molecular identity (Psickle), leading to elevated intracellular [Ca2+] ([Ca2+]i) and subsequent activation of KCa 3.1. The resulting erythrocyte volume decrease elevates intracellular hemoglobin S (HbSS) concentration, accelerates deoxygenation-induced HbSS polymerization, and increases the likelihood of cell sickling. Deoxygenation-induced currents sharing some properties of Psickle have been recorded from sickle erythrocytes in whole cell configuration. Methodology/Principal Findings We now show by cell-attached and nystatin-permeabilized patch clamp recording from sickle erythrocytes of mouse and human that deoxygenation reversibly activates a Ca2+- and cation-permeable conductance sensitive to inhibition by Grammastola spatulata mechanotoxin-4 (GsMTx-4; 1 µM), dipyridamole (100 µM), DIDS (100 µM), and carbon monoxide (25 ppm pretreatment). Deoxygenation also elevates sickle erythrocyte [Ca2+]i, in a manner similarly inhibited by GsMTx-4 and by carbon monoxide. Normal human and mouse erythrocytes do not exhibit these responses to deoxygenation. Deoxygenation-induced elevation of [Ca2+]i in mouse sickle erythrocytes did not require KCa3.1 activity. Conclusions/Significance The electrophysiological and fluorimetric data provide compelling evidence in sickle erythrocytes of mouse and human for a deoxygenation-induced, reversible, Ca2+-permeable cation conductance blocked by inhibition of HbSS polymerization and by an inhibitor of strctch-activated cation channels. This cation permeability pathway is likely an important source of intracellular Ca2+ for pathologic activation of KCa3.1 in sickle erythrocytes. Blockade of this pathway represents a novel therapeutic approach for treatment of sickle disease.
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Affiliation(s)
- David H. Vandorpe
- Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Renal Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chang Xu
- Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Renal Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Boris E. Shmukler
- Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Renal Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Leo E. Otterbein
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Marie Trudel
- Institut de Recherches Cliniques de Montreal, Montreal, Quebec, Canada
| | - Frederick Sachs
- Department of Physiology and Biophysics, University of Buffalo, Buffalo, New York, United States of America
| | - Philip A. Gottlieb
- Department of Physiology and Biophysics, University of Buffalo, Buffalo, New York, United States of America
| | - Carlo Brugnara
- Department of Laboratory Medicine, Children's Hospital Boston Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Seth L. Alper
- Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Renal Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Acid-sensitive outwardly rectifying anion channels in human erythrocytes. J Membr Biol 2009; 230:1-10. [PMID: 19572091 DOI: 10.1007/s00232-009-9179-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 05/22/2009] [Indexed: 12/14/2022]
Abstract
Acid-sensitive outwardly rectifying anion channels (ASOR) have been described in several mammalian cell types. The present whole-cell patch-clamp study elucidated whether those channels are expressed in erythrocytes. To this end whole-cell recordings were made in human erythrocytes from healthy donors treated with low pH and high osmotic pressure. When the pipette solution had a reduced Cl(-) concentration, treatment of the cells with Cl(-)-containing normal and hyperosmotic (addition of sucrose and polyethelene glycol 1000 [PEG-1000] to the Ringer) media with low pH significantly increased the conductance of the cells at positive voltages. Channel activity was highest in the PEG-1000 media (95 and 300 mM PEG-1000, pH 4.5 and 4.3, respectively) where the current-voltage curves demonstrated strong outward rectification and reversed at -40 mV. Substitution of the Cl(-)-containing medium with Cl(-)-free medium resulted in a decrease of the conductance at hyperpolarizing voltages, a shift in reversal potential (to 0 mV) and loss of outward rectification. The chloride currents were inhibited by chloride channels blockers DIDS and NPPB (IC(50) for both was approximately 1 mM) but not with niflumic acid and amiloride. The observations reveal expression of ASOR in erythrocytes.
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Alper SL. Molecular physiology and genetics of Na+-independent SLC4 anion exchangers. J Exp Biol 2009; 212:1672-83. [PMID: 19448077 PMCID: PMC2683012 DOI: 10.1242/jeb.029454] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2009] [Indexed: 01/12/2023]
Abstract
Plasmalemmal Cl(-)/HCO(3)(-) exchangers are encoded by the SLC4 and SLC26 gene superfamilies, and function to regulate intracellular pH, [Cl(-)] and cell volume. The Cl(-)/HCO(3)(-) exchangers of polarized epithelial cells also contribute to transepithelial secretion and reabsorption of acid-base equivalents and Cl(-). This review focuses on Na(+)-independent electroneutral Cl(-)/HCO(3)(-) exchangers of the SLC4 family. Human SLC4A1/AE1 mutations cause the familial erythroid disorders of spherocytic anemia, stomatocytic anemia and ovalocytosis. A largely discrete set of AE1 mutations causes familial distal renal tubular acidosis. The Slc4a2/Ae2(-/-) mouse dies before weaning with achlorhydria and osteopetrosis. A hypomorphic Ae2(-/-) mouse survives to exhibit male infertility with defective spermatogenesis and a syndrome resembling primary biliary cirrhosis. A human SLC4A3/AE3 polymorphism is associated with seizure disorder, and the Ae3(-/-) mouse has increased seizure susceptibility. The transport mechanism of mammalian SLC4/AE polypeptides is that of electroneutral Cl(-)/anion exchange, but trout erythroid Ae1 also mediates Cl(-) conductance. Erythroid Ae1 may mediate the DIDS-sensitive Cl(-) conductance of mammalian erythrocytes, and, with a single missense mutation, can mediate electrogenic SO(4)(2-)/Cl(-) exchange. AE1 trafficking in polarized cells is regulated by phosphorylation and by interaction with other proteins. AE2 exhibits isoform-specific patterns of acute inhibition by acidic intracellular pH and independently by acidic extracellular pH. In contrast, AE2 is activated by hypertonicity and, in a pH-independent manner, by ammonium and by hypertonicity. A growing body of structure-function and interaction data, together with emerging information about physiological function and structure, is advancing our understanding of SLC4 anion exchangers.
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Affiliation(s)
- Seth L Alper
- Renal Division and Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
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