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Liu J, Miao M, Wei F. Angelicin Alleviates Maternal Isoflurane Exposure-Induced Offspring Cognitive Defects Through the Carbonic Anhydrase 4/Aquaporin-4 Pathway. Mol Biotechnol 2024; 66:34-43. [PMID: 36997697 DOI: 10.1007/s12033-023-00723-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 03/13/2023] [Indexed: 04/03/2023]
Abstract
An increasing number of studies reveal the deleterious effects of isoflurane (Iso) exposure during pregnancy on offspring cognition. However, no effective therapeutic strategy for Iso-induced deleterious effects has been well developed. Angelicin exerts an anti-inflammatory effect on neurons and glial cells. This study investigated the roles and mechanism of action of angelicin in Iso-induced neurotoxicity in vitro and in vivo. After exposing C57BL/6 J mice on embryonic day 15 (E15) to Iso for 3 and 6 h, respectively, neonatal mice on embryonic day 18 (E18) displayed obvious anesthetic neurotoxicity, which was revealed by the elevation of cerebral inflammatory factors and blood-brain barrier (BBB) permeability and cognitive dysfunction in mice. Angelicin treatment could not only significantly reduce the Iso-induced embryonic inflammation and BBB disruption but also improve the cognitive dysfunction of offspring mice. Iso exposure resulted in an increase of carbonic anhydrase (CA) 4 and aquaporin-4 (AQP4) expression at both mRNA and protein levels in vascular endothelial cells and mouse brain tissue collected from neonatal mice on E18. Remarkably, the Iso-induced upregulation of CA4 and AQP4 expression could be partially reversed by angelicin treatment. Moreover, GSK1016790A, an AQP4 agonist, was used to confirm the role of AQP4 in the protective effect of angelicin. Results showed that GSK1016790A abolished the therapeutic effect of angelicin on Iso-induced inflammation and BBB disruption in the embryonic brain and on the cognitive function of offspring mice. In conclusion, angelicin may serve as a potential therapeutic for Iso-induced neurotoxicity in neonatal mice by regulating the CA4/AQP4 pathway.
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Affiliation(s)
- Jingying Liu
- Department of Obstetrical, Yantaishan Hospital, Yantai, 264000, Shandong, China
| | - Meijuan Miao
- Department of Anesthesiology, Feicheng People's Hospital, Feicheng, 271600, Shandong, China
| | - Fujiang Wei
- Department of Anesthesiology, Yantaishan Hospital, No. 91 Jiefang Road, Zhifu District, Yantai, 264000, Shandong, China.
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Zannad F, Ferreira JP, Butler J, Filippatos G, Januzzi JL, Sumin M, Zwick M, Saadati M, Pocock SJ, Sattar N, Anker SD, Packer M. Effect of empagliflozin on circulating proteomics in heart failure: mechanistic insights into the EMPEROR programme. Eur Heart J 2022; 43:4991-5002. [PMID: 36017745 PMCID: PMC9769969 DOI: 10.1093/eurheartj/ehac495] [Citation(s) in RCA: 75] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/15/2022] [Accepted: 08/25/2022] [Indexed: 01/12/2023] Open
Abstract
AIMS Sodium-glucose co-transporter 2 (SGLT2) inhibitors improve cardiovascular outcomes in diverse patient populations, but their mechanism of action requires further study. The aim is to explore the effect of empagliflozin on the circulating levels of intracellular proteins in patients with heart failure, using large-scale proteomics. METHODS AND RESULTS Over 1250 circulating proteins were measured at baseline, Week 12, and Week 52 in 1134 patients from EMPEROR-Reduced and EMPEROR-Preserved, using the Olink® Explore 1536 platform. Statistical and bioinformatical analyses identified differentially expressed proteins (empagliflozin vs. placebo), which were then linked to demonstrated biological actions in the heart and kidneys. At Week 12, 32 of 1283 proteins fulfilled our threshold for being differentially expressed, i.e. their levels were changed by ≥10% with a false discovery rate <1% (empagliflozin vs. placebo). Among these, nine proteins demonstrated the largest treatment effect of empagliflozin: insulin-like growth factor-binding protein 1, transferrin receptor protein 1, carbonic anhydrase 2, erythropoietin, protein-glutamine gamma-glutamyltransferase 2, thymosin beta-10, U-type mitochondrial creatine kinase, insulin-like growth factor-binding protein 4, and adipocyte fatty acid-binding protein 4. The changes of the proteins from baseline to Week 52 were generally concordant with the changes from the baseline to Week 12, except empagliflozin reduced levels of kidney injury molecule-1 by ≥10% at Week 52, but not at Week 12. The most common biological action of differentially expressed proteins appeared to be the promotion of autophagic flux in the heart, kidney or endothelium, a feature of 6 proteins. Other effects of differentially expressed proteins on the heart included the reduction of oxidative stress, inhibition of inflammation and fibrosis, and the enhancement of mitochondrial health and energy, repair, and regenerative capacity. The actions of differentially expressed proteins in the kidney involved promotion of autophagy, integrity and regeneration, suppression of renal inflammation and fibrosis, and modulation of renal tubular sodium reabsorption. CONCLUSIONS Changes in circulating protein levels in patients with heart failure are consistent with the findings of experimental studies that have shown that the effects of SGLT2 inhibitors are likely related to actions on the heart and kidney to promote autophagic flux, nutrient deprivation signalling and transmembrane sodium transport.
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Affiliation(s)
- Faiez Zannad
- Corresponding author. Tel: +33 3 83 15 73 15, Fax: +33 3 83 15 73 24, Emails: ;
| | - João Pedro Ferreira
- Corresponding author. Tel: +33 3 83 15 73 15, Fax: +33 3 83 15 73 24, Emails: ;
| | - Javed Butler
- Heart and Vascular Research, Baylor Scott and White Research Institute, 34 Live Oak St Ste 501, Dallas, TX 75204, USA,University of Mississippi Medical Center, 2500 North State Street Jackson, MS 39216, USA
| | - Gerasimos Filippatos
- Heart Failure Unit, National and Kapodistrian University of Athens School of Medicine, Mikras Asias 75, Athina 115 27 Athens, Greece
| | - James L Januzzi
- Massachusetts General Hospital, Harvard Medical School, 55 Fruit St, Boston, MA 02114USA,The Baim Institute for Clinical Research, 930 Commonwealth Ave #3, Boston, MA 02215USA
| | - Mikhail Sumin
- Boehringer Ingelheim International GmbH, Binger Str. 173, 55218 Ingelheim am RheinGermany
| | - Matthias Zwick
- Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Str. 65, 88400 Biberach an der RissGermany
| | - Maral Saadati
- Elderbrook Solutions GmbH on behalf of Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Str. 65, 88400 Biberach an der Riss, Germany
| | - Stuart J Pocock
- London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HTUK
| | - Naveed Sattar
- BHF, UK School of Cardiovascular and Metabolic Health, University of Glasgow, 126 University Place, Glasgow G12 8TAUK
| | - Stefan D Anker
- Department of Cardiology (CVK) Berlin Institute of Health Center for Regenerative Therapies (BCRT) German Centre for Cardiovascular Research (DZHK) partner site Berlin, Charité Universitätsmedizin Berlin, Charité, Campus Virchow-Klinikum, Augustenburger Platz 1, D-13353 Berlin, Germany,Institute of Heart Diseases, Wroclaw Medical University, Borowska Street 213, 50-556 Warsaw, Poland
| | - Milton Packer
- Baylor Heart and Vascular Hospital, Baylor University Medical Center, 621 N Hall St, Dallas, TX 75226, USA,Imperial College, London, Exhibition Rd, South Kensington, London SW7 2BX, UK
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Dotsenko OI. The whole-cell kinetic metabolic model of the pH regulation mechanisms in human erythrocytes. REGULATORY MECHANISMS IN BIOSYSTEMS 2022. [DOI: 10.15421/022235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Mathematical modeling in recent years helped to obtain answers to questions that were difficult or even impossible to answer experimentally, to predict several unexpected connections in cell metabolism and to understand and importance of certain biochemical reactions. Due to the complexity and variety of processes underlying the mechanisms of intracellular pH (pHi) regulation, mathematical modeling and metabolome analysis are powerful tools for their analysis. In this regard, a mathematical metabolic model for human erythrocytes was created, which combines cellular metabolism with acid-base processes and gas exchange. The model consists of the main metabolic pathways, such as glycolysis, the pentose phosphate pathway, some membrane transport systems, and interactions between hemoglobin and metabolites. The Jacobs-Stewart cycle, which is fundamental in gas exchange and pH regulation, was included to these pathways. The model was created in the COPASI environment, consisted of 85 reactions, the rate of which is based on accurate kinetic equations. The time dependences of reaction flows and metabolite concentrations, as an outcome of calculations, allowed us to reproduce the behaviour of the metabolic system after its disturbance in vitro and to establish the recovery mechanisms or approximation to stationary states. The COPASI simulation environment provides model flexibility by reproducing any experimental design by optimizing direct quantitative comparisons between measured and predicted results. Thus, the procedure of parameters optimization (Parameter Estimation) followed by the solution of the model’s differential equations (Time Course procedure) was used to predict the behaviour of all measured and unmeasured variables over time. The initial intracellular concentrations of CO2, HCO3– in human erythrocytes used for incubation in a phosphate buffer medium were calculated. Changes in CO2, HCO3– content over time were shown. It was established that the regulation of pH in erythrocytes placed in a buffer medium takes place with the participation of two types of processes – fast (takes place in 1.3 s) and slow. It is shown that fast processes are aimed at restoring the intracellular balance between CO2 and HCO3–, slow processes are aimed at establishing the balance of H+ between the cell and the extracellular environment. The role of carbonic anhydrase (CA) and hemoglobin in the processes of pH stabilization is shown and analyzed. The physiological role of the metabolon between band 3 protein (AE1), CA, aquaporin and hemoglobin in maintaining pH homeostasis in the conditions of in vitro experiments are discussed.
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Takei Y. The digestive tract as an essential organ for water acquisition in marine teleosts: lessons from euryhaline eels. ZOOLOGICAL LETTERS 2021; 7:10. [PMID: 34154668 PMCID: PMC8215749 DOI: 10.1186/s40851-021-00175-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 04/16/2021] [Indexed: 05/17/2023]
Abstract
Adaptation to a hypertonic marine environment is one of the major topics in animal physiology research. Marine teleosts lose water osmotically from the gills and compensate for this loss by drinking surrounding seawater and absorbing water from the intestine. This situation is in contrast to that in mammals, which experience a net osmotic loss of water after drinking seawater. Water absorption in fishes is made possible by (1) removal of monovalent ions (desalinization) by the esophagus, (2) removal of divalent ions as carbonate (Mg/CaCO3) precipitates promoted by HCO3- secretion, and (3) facilitation of NaCl and water absorption from diluted seawater by the intestine using a suite of unique transporters. As a result, 70-85% of ingested seawater is absorbed during its passage through the digestive tract. Thus, the digestive tract is an essential organ for marine teleost survival in the hypertonic seawater environment. The eel is a species that has been frequently used for osmoregulation research in laboratories worldwide. The eel possesses many advantages as an experimental animal for osmoregulation studies, one of which is its outstanding euryhalinity, which enables researchers to examine changes in the structure and function of the digestive tract after direct transfer from freshwater to seawater. In recent years, the molecular mechanisms of ion and water transport across epithelial cells (the transcellular route) and through tight junctions (the paracellular route) have been elucidated for the esophagus and intestine. Thanks to the rapid progress in analytical methods for genome databases on teleosts, including the eel, the molecular identities of transporters, channels, pumps and junctional proteins have been clarified at the isoform level. As 10 y have passed since the previous reviews on this subject, it seems relevant and timely to summarize recent progress in research on the molecular mechanisms of water and ion transport in the digestive tract in eels and to compare the mechanisms with those of other teleosts and mammals from comparative and evolutionary viewpoints. We also propose future directions for this research field to achieve integrative understanding of the role of the digestive tract in adaptation to seawater with regard to pathways/mechanisms including the paracellular route, divalent ion absorption, metabolon formation and cellular trafficking of transporters. Notably, some of these have already attracted practical attention in laboratories.
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Affiliation(s)
- Yoshio Takei
- Laboratory of Physiology, Department of Marine Bioscience, Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8564, Japan.
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Kazokaitė-Adomaitienė J, Becker HM, Smirnovienė J, Dubois LJ, Matulis D. Experimental Approaches to Identify Selective Picomolar Inhibitors for Carbonic Anhydrase IX. Curr Med Chem 2021; 28:3361-3384. [PMID: 33138744 DOI: 10.2174/0929867327666201102112841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 08/14/2020] [Accepted: 08/16/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Carbonic anhydrases (CAs) regulate pH homeostasis via the reversible hydration of CO2, thereby emerging as essential enzymes for many vital functions. Among 12 catalytically active CA isoforms in humans, CA IX has become a relevant therapeutic target because of its role in cancer progression. Only two CA IX inhibitors have entered clinical trials, mostly due to low affinity and selectivity properties. OBJECTIVE The current review presents the design, development, and identification of the selective nano- to picomolar CA IX inhibitors VD11-4-2, VR16-09, and VD12-09. METHODS AND RESULTS Compounds were selected from our database, composed of over 400 benzensulfonamides, synthesized at our laboratory, and tested for their binding to 12 human CAs. Here we discuss the CA CO2 hydratase activity/inhibition assay and several biophysical techniques, such as fluorescent thermal shift assay and isothermal titration calorimetry, highlighting their contribution to the analysis of compound affinity and structure- activity relationships. To obtain sufficient amounts of recombinant CAs for inhibitor screening, several gene cloning and protein purification strategies are presented, including site-directed CA mutants, heterologous CAs from Xenopus oocytes, and native endogenous CAs. The cancer cell-based methods, such as clonogenicity, extracellular acidification, and mass spectrometric gas-analysis are reviewed, confirming nanomolar activities of lead inhibitors in intact cancer cells. CONCLUSIONS Novel CA IX inhibitors are promising derivatives for in vivo explorations. Furthermore, the simultaneous targeting of several proteins involved in proton flux upon tumor acidosis and the disruption of transport metabolons might improve cancer management.
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Affiliation(s)
- Justina Kazokaitė-Adomaitienė
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Holger M Becker
- Institute of Physiological Chemistry, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Joana Smirnovienė
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Ludwig J Dubois
- The M-Lab, Department of Precision Medicine, GROW - School for Oncology and Developmental Biology, Maastricht University, Netherlands
| | - Daumantas Matulis
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
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Patel S, McKeon D, Sao K, Yang C, Naranjo NM, Svitkina TM, Petrie RJ. Myosin II and Arp2/3 cross-talk governs intracellular hydraulic pressure and lamellipodia formation. Mol Biol Cell 2021; 32:579-589. [PMID: 33502904 PMCID: PMC8101460 DOI: 10.1091/mbc.e20-04-0227] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Human fibroblasts can switch between lamellipodia-dependent and -independent migration mechanisms on two-dimensional surfaces and in three-dimensional (3D) matrices. RhoA GTPase activity governs the switch from low-pressure lamellipodia to high-pressure lobopodia in response to the physical structure of the 3D matrix. Inhibiting actomyosin contractility in these cells reduces intracellular pressure and reverts lobopodia to lamellipodial protrusions via an unknown mechanism. To test the hypothesis that high pressure physically prevents lamellipodia formation, we manipulated pressure by activating RhoA or changing the osmolarity of the extracellular environment and imaged cell protrusions. We find RhoA activity inhibits Rac1-mediated lamellipodia formation through two distinct pathways. First, RhoA boosts intracellular pressure by increasing actomyosin contractility and water influx but acts upstream of Rac1 to inhibit lamellipodia formation. Increasing osmotic pressure revealed a second RhoA pathway, which acts through nonmuscle myosin II (NMII) to disrupt lamellipodia downstream from Rac1 and elevate pressure. Interestingly, Arp2/3 inhibition triggered a NMII-dependent increase in intracellular pressure, along with lamellipodia disruption. Together, these results suggest that actomyosin contractility and water influx are coordinated to increase intracellular pressure, and RhoA signaling can inhibit lamellipodia formation via two distinct pathways in high-pressure cells.
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Affiliation(s)
- Shivani Patel
- Department of Biology, Drexel University, Philadelphia, PA 19104
| | - Donna McKeon
- Department of Biology, Drexel University, Philadelphia, PA 19104
| | - Kimheak Sao
- Department of Biology, Drexel University, Philadelphia, PA 19104
| | - Changsong Yang
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104
| | - Nicole M Naranjo
- Department of Biology, Drexel University, Philadelphia, PA 19104
| | - Tatyana M Svitkina
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104
| | - Ryan J Petrie
- Department of Biology, Drexel University, Philadelphia, PA 19104
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Plain A, Pan W, O’Neill D, Ure M, Beggs MR, Farhan M, Dimke H, Cordat E, Alexander RT. Claudin-12 Knockout Mice Demonstrate Reduced Proximal Tubule Calcium Permeability. Int J Mol Sci 2020; 21:ijms21062074. [PMID: 32197346 PMCID: PMC7139911 DOI: 10.3390/ijms21062074] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/11/2020] [Accepted: 03/15/2020] [Indexed: 01/13/2023] Open
Abstract
The renal proximal tubule (PT) is responsible for the reabsorption of approximately 65% of filtered calcium, primarily via a paracellular pathway. However, which protein(s) contribute this paracellular calcium pore is not known. The claudin family of tight junction proteins confers permeability properties to an epithelium. Claudin-12 is expressed in the kidney and when overexpressed in cell culture contributes paracellular calcium permeability (PCa). We therefore examined claudin-12 renal localization and its contribution to tubular paracellular calcium permeability. Claudin-12 null mice (KO) were generated by replacing the single coding exon with β-galactosidase from Escherichia coli. X-gal staining revealed that claudin-12 promoter activity colocalized with aquaporin-1, consistent with the expression in the PT. PTs were microperfused ex vivo and PCa was measured. PCa in PTs from KO mice was significantly reduced compared with WT mice. However, urinary calcium excretion was not different between genotypes, including those on different calcium containing diets. To assess downstream compensation, we examined renal mRNA expression. Claudin-14 expression, a blocker of PCa in the thick ascending limb (TAL), was reduced in the kidney of KO animals. Thus, claudin-12 is expressed in the PT, where it confers paracellular calcium permeability. In the absence of claudin-12, reduced claudin-14 expression in the TAL may compensate for reduced PT calcium reabsorption.
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Affiliation(s)
- Allein Plain
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Wanling Pan
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Deborah O’Neill
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Megan Ure
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Megan R. Beggs
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
- The Women’s & Children’s Health Research Institute, 11405-87 Avenue, Edmonton, AB T6G 1C9 Canada;
| | - Maikel Farhan
- The Women’s & Children’s Health Research Institute, 11405-87 Avenue, Edmonton, AB T6G 1C9 Canada;
- Department of Pediatrics, The University of Alberta, Edmonton, AB T6J 2R7, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, 5230 Odense, Denmark;
- Department of Nephrology, Odense University Hospital, 5000 Odense, Denmark
| | - Emmanuelle Cordat
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - R. Todd Alexander
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
- The Women’s & Children’s Health Research Institute, 11405-87 Avenue, Edmonton, AB T6G 1C9 Canada;
- Department of Pediatrics, The University of Alberta, Edmonton, AB T6J 2R7, Canada
- Correspondence: ; Tel.: +1-(780)-248-5560
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Hsu K. Exploring the Potential Roles of Band 3 and Aquaporin-1 in Blood CO 2 Transport-Inspired by Comparative Studies of Glycophorin B-A-B Hybrid Protein GP.Mur. Front Physiol 2018; 9:733. [PMID: 29971013 PMCID: PMC6018491 DOI: 10.3389/fphys.2018.00733] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 05/25/2018] [Indexed: 12/15/2022] Open
Abstract
The Cl—/HCO3— exchanger band 3 is functionally relevant to blood CO2 transport. Band 3 is the most abundant membrane protein in human red blood cells (RBCs). Our understanding of its physiological functions mainly came from clinical cases associated with band 3 mutations. Severe reduction in band 3 expression affects blood HCO3—/CO2 metabolism. What could happen physiologically if band 3 expression is elevated instead? In some areas of Southeast Asia, about 1–10% of the populations express GP.Mur, a glycophorin B-A-B hybrid membrane protein important in the field of transfusion medicine. GP.Mur functions to promote band 3 expression, and GP.Mur red cells can be deemed as a naturally occurred model for higher band 3 expression. This review first compares the functional consequences of band 3 at different levels, and suggests a critical role of band 3 in postnatal CO2 respiration. The second part of the review explores the transport of water, which is the other substrate for intra-erythrocytic CO2/HCO3— conversion (an essential step in blood CO2 transport). Despite that water is considered unlimited physiologically, it is unclear whether water channel aquaporin-1 (AQP1) abundantly expressed in RBCs is functionally involved in CO2 transport. Research in this area is complicated by the fact that the H2O/CO2-transporting function of AQP1 is replaceable by other erythrocyte channels/transporters (e.g., UT-B/GLUT1 for H2O; RhAG for CO2). Recently, using carbonic anhydrase II (CAII)-filled erythrocyte vesicles, AQP1 has been demonstrated to transport water for the CAII-mediated reaction, CO2(g) + H2O ⇌ HCO3—(aq) + H+(aq). AQP1 is structurally associated with some population of band 3 complexes on the erythrocyte membrane in an osmotically responsive fashion. The current findings reveal transient interaction among components within the band 3-central, CO2-transport metabolon (AQP1, band 3, CAII and deoxygenated hemoglobin). Their dynamic interaction is envisioned to facilitate blood CO2 respiration, in the presence of constantly changing osmotic and hemodynamic stresses during circulation.
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Affiliation(s)
- Kate Hsu
- Transfusion Medicine and Immunogenetics Laboratories, MacKay Memorial Hospital, Tamsui, Taiwan
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Kourghi M, Pei JV, De Ieso ML, Nourmohammadi S, Chow PH, Yool AJ. Fundamental structural and functional properties of Aquaporin ion channels found across the kingdoms of life. Clin Exp Pharmacol Physiol 2018; 45:401-409. [PMID: 29193257 DOI: 10.1111/1440-1681.12900] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/06/2017] [Accepted: 11/16/2017] [Indexed: 01/09/2023]
Abstract
Aquaporin (AQP) channels in the major intrinsic protein (MIP) family are known to facilitate transmembrane water fluxes in prokaryotes and eukaryotes. Some classes of AQPs also conduct ions, glycerol, urea, CO2 , nitric oxide, and other small solutes. Ion channel activity has been demonstrated for mammalian AQPs 0, 1, 6, Drosophila Big Brain (BIB), soybean nodulin 26, and rockcress AtPIP2;1. More classes are likely to be discovered. Newly identified blockers are providing essential tools for establishing physiological roles of some of the AQP dual water and ion channels. For example, the arylsulfonamide AqB011 which selectively blocks the central ion pore of mammalian AQP1 has been shown to impair migration of HT29 colon cancer cells. Traditional herbal medicines are sources of selective AQP1 inhibitors that also slow cancer cell migration. The finding that plant AtPIP2;1 expressed in root epidermal cells mediates an ion conductance regulated by calcium and protons provided insight into molecular mechanisms of environmental stress responses. Expression of lens MIP (AQP0) is essential for maintaining the structure, integrity and transparency of the lens, and Drosophila BIB contributes to neurogenic signalling pathways to control the developmental fate of fly neuroblast cells; however, the ion channel roles remain to be defined for MIP and BIB. A broader portfolio of pharmacological agents is needed to investigate diverse AQP ion channel functions in situ. Understanding the dual water and ion channel roles of AQPs could inform the development of novel agents for rational interventions in diverse challenges from agriculture to human health.
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Affiliation(s)
- Mohamad Kourghi
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Jinxin V Pei
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Michael L De Ieso
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | | | - Pak Hin Chow
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Andrea J Yool
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
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Krishnan D, Pan W, Beggs MR, Trepiccione F, Chambrey R, Eladari D, Cordat E, Dimke H, Alexander RT. Deficiency of Carbonic Anhydrase II Results in a Urinary Concentrating Defect. Front Physiol 2018; 8:1108. [PMID: 29354070 PMCID: PMC5760551 DOI: 10.3389/fphys.2017.01108] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 12/14/2017] [Indexed: 01/23/2023] Open
Abstract
Carbonic anhydrase II (CAII) is expressed along the nephron where it interacts with a number of transport proteins augmenting their activity. Aquaporin-1 (AQP1) interacts with CAII to increase water flux through the water channel. Both CAII and aquaporin-1 are expressed in the thin descending limb (TDL); however, the physiological role of a CAII-AQP1 interaction in this nephron segment is not known. To determine if CAII was required for urinary concentration, we studied water handling in CAII-deficient mice. CAII-deficient mice demonstrate polyuria and polydipsia as well as an alkaline urine and bicarbonaturia, consistent with a type III renal tubular acidosis. Natriuresis and hypercalciuria cause polyuria, however, CAII-deficient mice did not have increased urinary sodium nor calcium excretion. Further examination revealed dilute urine in the CAII-deficient mice. Urinary concentration remained reduced in CAII-deficient mice relative to wild-type animals even after water deprivation. The renal expression and localization by light microscopy of NKCC2 and aquaporin-2 was not altered. However, CAII-deficient mice had increased renal AQP1 expression. CAII associates with and increases water flux through aquaporin-1. Water flux through aquaporin-1 in the TDL of the loop of Henle is essential to the concentration of urine, as this is required to generate a concentrated medullary interstitium. We therefore measured cortical and medullary interstitial concentration in wild-type and CAII-deficient mice. Mice lacking CAII had equivalent cortical interstitial osmolarity to wild-type mice: however, they had reduced medullary interstitial osmolarity. We propose therefore that reduced water flux through aquaporin-1 in the TDL in the absence of CAII prevents the generation of a maximally concentrated medullary interstitium. This, in turn, limits urinary concentration in CAII deficient mice.
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Affiliation(s)
- Devishree Krishnan
- Department of Physiology, University of Alberta, Edmonton, AB, Canada.,The Women's and Children's Health Research Institute, Edmonton, AB, Canada
| | - Wanling Pan
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, AB, Canada.,The Women's and Children's Health Research Institute, Edmonton, AB, Canada
| | - Francesco Trepiccione
- Department of Cardio-Thoracic and Respiratory Science, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Régine Chambrey
- Institut National de la Santé et de la Recherche Médicale Diabète athérothrombose Thérapies Réunion Océan Indien (DéTROI) Université de La Réunion, CYROI, La Réunion, France.,Centre National de la Recherche Scientifique, Délégation Paris Michel-Ange, Sainte-Clotilde, France
| | - Dominique Eladari
- Institut National de la Santé et de la Recherche Médicale Diabète athérothrombose Thérapies Réunion Océan Indien (DéTROI) Université de La Réunion, CYROI, La Réunion, France.,Service d'Explorations Fonctionnelles Rénales, Hôpital Felix Guyon, Centre Hospitalier Universitaire de la Réunion, La Réunion, France
| | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, AB, Canada.,The Women's and Children's Health Research Institute, Edmonton, AB, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB, Canada.,The Women's and Children's Health Research Institute, Edmonton, AB, Canada.,Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
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12
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Hsu K, Lee TY, Periasamy A, Kao FJ, Li LT, Lin CY, Lin HJ, Lin M. Adaptable interaction between aquaporin-1 and band 3 reveals a potential role of water channel in blood CO 2 transport. FASEB J 2017; 31:4256-4264. [PMID: 28596233 DOI: 10.1096/fj.201601282r] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 05/22/2017] [Indexed: 12/22/2022]
Abstract
Human CO2 respiration requires rapid conversion between CO2 and HCO3- Carbonic anhydrase II facilitates this reversible reaction inside red blood cells, and band 3 [anion exchanger 1 (AE1)] provides a passage for HCO3- flux across the cell membrane. These 2 proteins are core components of the CO2 transport metabolon. Intracellular H2O is necessary for CO2/HCO3- conversion. However, abundantly expressed aquaporin 1 (AQP1) in erythrocytes is thought not to be part of band 3 complexes or the CO2 transport metabolon. To solve this conundrum, we used Förster resonance energy transfer (FRET) measured by fluorescence lifetime imaging (FLIM-FRET) and identified interaction between aquaporin-1 and band 3 at a distance of 8 nm, within the range of dipole-dipole interaction. Notably, their interaction was adaptable to membrane tonicity changes. This suggests that the function of AQP1 in tonicity response could be coupled or correlated to its function in band 3-mediated CO2/HCO3- exchange. By demonstrating AQP1 as a mobile component of the CO2 transport metabolon, our results uncover a potential role of water channel in blood CO2 transport and respiration.-Hsu, K., Lee, T.-Y., Periasamy, A., Kao, F.-J., Li, L.-T., Lin, C.-Y., Lin, H.-J., Lin, M. Adaptable interaction between aquaporin-1 and band 3 reveals a potential role of water channel in blood CO2 transport.
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Affiliation(s)
- Kate Hsu
- Transfusion Medicine Laboratory, Mackay Memorial Hospital, Tamsui, Taiwan;
| | - Ting-Ying Lee
- Transfusion Medicine Laboratory, Mackay Memorial Hospital, Tamsui, Taiwan
| | - Ammasi Periasamy
- W. M. Keck Center for Cellular Imaging, University of Virginia, Charlottesville, Virginia, USA
| | - Fu-Jen Kao
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | - Li-Tzu Li
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Chuang-Yu Lin
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Hui-Ju Lin
- Transfusion Medicine Laboratory, Mackay Memorial Hospital, Tamsui, Taiwan
| | - Marie Lin
- Transfusion Medicine Laboratory, Mackay Memorial Hospital, Tamsui, Taiwan
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13
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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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14
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Genetet S, Desrames A, Chouali Y, Ripoche P, Lopez C, Mouro-Chanteloup I. Stomatin modulates the activity of the Anion Exchanger 1 (AE1, SLC4A1). Sci Rep 2017; 7:46170. [PMID: 28387307 PMCID: PMC5383999 DOI: 10.1038/srep46170] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 03/09/2017] [Indexed: 12/17/2022] Open
Abstract
Anion Exchanger 1 (AE1) and stomatin are integral proteins of the red blood cell (RBC) membrane. Erythroid and kidney AE1 play a major role in HCO3- and Cl- exchange. Stomatins down-regulate the activity of many channels and transporters. Biochemical studies suggested an interaction of erythroid AE1 with stomatin. Moreover, we previously reported normal AE1 expression level in stomatin-deficient RBCs. Here, the ability of stomatin to modulate AE1-dependent Cl-/HCO3- exchange was evaluated using stopped-flow methods. In HEK293 cells expressing recombinant AE1 and stomatin, the permeabilities associated with AE1 activity were 30% higher in cells overexpressing stomatin, compared to cells with only endogenous stomatin expression. Ghosts from stomatin-deficient RBCs and controls were resealed in the presence of pH- or chloride-sensitive fluorescent probes and submitted to inward HCO3- and outward Cl- gradients. From alkalinization rate constants, we deduced a 47% decreased permeability to HCO3- for stomatin-deficient patients. Similarly, kinetics of Cl- efflux, followed by the probe dequenching, revealed a significant 42% decrease in patients. In situ Proximity Ligation Assays confirmed an interaction of AE1 with stomatin, in both HEK recombinant cells and RBCs. Here we show that stomatin modulates the transport activity of AE1 through a direct protein-protein interaction.
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Affiliation(s)
- Sandrine Genetet
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, 75739 Paris Cedex 15, France
| | - Alexandra Desrames
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, 75739 Paris Cedex 15, France
| | - Youcef Chouali
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, 75739 Paris Cedex 15, France
| | - Pierre Ripoche
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, 75739 Paris Cedex 15, France
| | - Claude Lopez
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, 75739 Paris Cedex 15, France
| | - Isabelle Mouro-Chanteloup
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, 75739 Paris Cedex 15, France
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15
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Momayyezi M, Guy RD. Substantial role for carbonic anhydrase in latitudinal variation in mesophyll conductance of Populus trichocarpa Torr. & Gray. PLANT, CELL & ENVIRONMENT 2017; 40:138-149. [PMID: 27761902 DOI: 10.1111/pce.12851] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/14/2016] [Accepted: 10/16/2016] [Indexed: 06/06/2023]
Abstract
In Populus trichocarpa (black cottonwood), net photosynthesis (An ) varies with latitude and, in northern genotypes, is supported by higher stomatal conductance (gs ). We report here a parallel cline in mesophyll conductance (gm ) and link this variation to carbonic anhydrase (CA) activity. Using concurrent carbon isotope discrimination and chlorophyll fluorescence methods, we examined the effects of acetazolamide, an inhibitor of CA, on gm in six representative genotypes (three from either end of the north-south cline). Acetazolamide reduced CA activity, gm , gs , chloroplast CO2 concentration (Cc ) and An at normal CO2 (400 μmol mol-1 ), the latter being reversible at saturating CO2 . Absolute reductions in An , gm and CA activity were greater in northern genotypes than in southern genotypes (P < 0.025) but percent reductions were similar. In contrast, northern genotypes showed lower percent reduction in Cc compared to southern genotypes (P < 0.025). The northern genotypes had greater CA activity relative to both leaf area (two-fold) and mass (1.8-fold) (P < 0.016). The relationship between CA activity and gm was similar whether the variation was inherent or inhibitor induced. We suggest that greater CA activity contributes to higher gm in northern P. trichocarpa genotypes, but other diffusion pathway components may also be involved.
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Affiliation(s)
- Mina Momayyezi
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Forest Sciences Centre, 2424 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Robert D Guy
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Forest Sciences Centre, 2424 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada
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16
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Kengkoom K, Ampawong S. In Vitro Protective Effect of Phikud Navakot Extraction on Erythrocyte. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2016; 2016:1961327. [PMID: 28003847 PMCID: PMC5149699 DOI: 10.1155/2016/1961327] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 11/03/2016] [Indexed: 11/27/2022]
Abstract
Phikud Navakot (PN), Thai herbal remedy in National List of Essential Medicines, has been claimed to reduce many cardiovascular symptoms especially dizziness and fainting. Apart from blood supply, erythrocyte morphology, in both shape and size, is one of the main consideration factors in cardiovascular diseases and may be affected by vascular oxidative stress. However, little is known about antioxidative property of PN on erythrocyte to preserve red blood cell integrity. In this study, 1,000 μM hydrogen peroxide-induced oxidative stress was conducted on sheep erythrocyte. Three doses of PN (1, 0.5, and 0.25 mg/mL) and 10 μM of ascorbic acid were compared. The released hemoglobin absorbance was measured to demonstrate hemolysis. Electron microscopic and immunohistochemical studies were also performed to characterize dysmorphic erythrocyte and osmotic ability in relation to aquaporin- (AQP-) 1 expression, respectively. The results revealed that all doses of PN and ascorbic acid decreased the severity of dysmorphic erythrocyte, particularly echinocyte, acanthocyte, knizocyte, codocyte, clumping, and other malformations. However, the most effective was 0.5 mg/mL PN dosage. In addition, hydrostatic pressure may be increased in dysmorphic erythrocyte in association with AQP-1 upregulation. Our results demonstrated that PN composes antioxidative effect to maintain the integrity and osmotic ability on sheep erythrocyte.
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Affiliation(s)
- Kanchana Kengkoom
- Academic Services Office, National Laboratory Animal Center, Mahidol University, 999 Salaya, Puttamonthon, Nakorn Pathom 73170, Thailand
| | - Sumate Ampawong
- Department of Tropical Pathology, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok 10400, Thailand
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17
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Al-Haideri H, White MA, Kelly DJ. Major contribution of the type II beta carbonic anhydrase CanB (Cj0237) to the capnophilic growth phenotype ofCampylobacter jejuni. Environ Microbiol 2015; 18:721-35. [DOI: 10.1111/1462-2920.13092] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 10/11/2015] [Accepted: 10/12/2015] [Indexed: 11/28/2022]
Affiliation(s)
- Halah Al-Haideri
- Department of Molecular Biology and Biotechnology; The University of Sheffield; Firth Court, Western Bank Sheffield S10 2TN UK
| | - Michael A. White
- Department of Molecular Biology and Biotechnology; The University of Sheffield; Firth Court, Western Bank Sheffield S10 2TN UK
| | - David J. Kelly
- Department of Molecular Biology and Biotechnology; The University of Sheffield; Firth Court, Western Bank Sheffield S10 2TN UK
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18
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Swenson ER. Pharmacology of acute mountain sickness: old drugs and newer thinking. J Appl Physiol (1985) 2015; 120:204-15. [PMID: 26294748 DOI: 10.1152/japplphysiol.00443.2015] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 08/12/2015] [Indexed: 01/09/2023] Open
Abstract
Pharmacotherapy in acute mountain sickness (AMS) for the past half century has largely rested on the use of carbonic anhydrase (CA) inhibitors, such as acetazolamide, and corticosteroids, such as dexamethasone. The benefits of CA inhibitors are thought to arise from their known ventilatory stimulation and resultant greater arterial oxygenation from inhibition of renal CA and generation of a mild metabolic acidosis. The benefits of corticosteroids include their broad-based anti-inflammatory and anti-edemagenic effects. What has emerged from more recent work is the strong likelihood that drugs in both classes act on other pathways and signaling beyond their classical actions to prevent and treat AMS. For the CA inhibitors, these include reduction in aquaporin-mediated transmembrane water transport, anti-oxidant actions, vasodilation, and anti-inflammatory effects. In the case of corticosteroids, these include protection against increases in vascular endothelial and blood-brain barrier permeability, suppression of inflammatory cytokines and reactive oxygen species production, and sympatholysis. The loci of action of both classes of drug include the brain, but may also involve the lung as revealed by benefits that arise with selective administration to the lungs by inhalation. Greater understanding of their pluripotent actions and sites of action in AMS may help guide development of better drugs with more selective action and fewer side effects.
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Affiliation(s)
- Erik R Swenson
- Veterans Affairs Puget Sound Health Care System, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Washington, Seattle
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19
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Beitz E, Golldack A, Rothert M, von Bülow J. Challenges and achievements in the therapeutic modulation of aquaporin functionality. Pharmacol Ther 2015; 155:22-35. [PMID: 26277280 DOI: 10.1016/j.pharmthera.2015.08.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Aquaporin (AQP) water and solute channels have basic physiological functions throughout the human body. AQP-facilitated water permeability across cell membranes is required for rapid reabsorption of water from pre-urine in the kidneys and for sustained near isosmolar water fluxes e.g. in the brain, eyes, inner ear, and lungs. Cellular water permeability is further connected to cell motility. AQPs of the aquaglyceroporin subfamily are necessary for lipid degradation in adipocytes and glycerol uptake into the liver, as well as for skin moistening. Modulation of AQP function is desirable in several pathophysiological situations, such as nephrogenic diabetes insipidus, Sjögren's syndrome, Menière's disease, heart failure, or tumors to name a few. Attempts to design or to find effective small molecule AQP inhibitors have yielded only a few hits. Challenges reside in the high copy number of AQP proteins in the cell membranes, and spatial restrictions in the protein structure. This review gives an overview on selected physiological and pathophysiological conditions in which modulation of AQP functions appears beneficial and discusses first achievements in the search of drug-like AQP inhibitors.
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Affiliation(s)
- Eric Beitz
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany.
| | - André Golldack
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany
| | - Monja Rothert
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany
| | - Julia von Bülow
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany
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20
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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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