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Peña-Münzenmayer G, George AT, Llontop N, Mazola Y, Apablaza N, Spichiger C, Brauchi S, Sarmiento J, Zúñiga L, González W, Catalán MA. K +-Driven Cl -/HCO 3- Exchange Mediated by Slc4a8 and Slc4a10. Int J Mol Sci 2024; 25:4575. [PMID: 38674160 PMCID: PMC11050268 DOI: 10.3390/ijms25084575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 04/11/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
Slc4a genes encode various types of transporters, including Na+-HCO3- cotransporters, Cl-/HCO3- exchangers, or Na+-driven Cl-/HCO3- exchangers. Previous research has revealed that Slc4a9 (Ae4) functions as a Cl-/HCO3- exchanger, which can be driven by either Na+ or K+, prompting investigation into whether other Slc4a members facilitate cation-dependent anion transport. In the present study, we show that either Na+ or K+ drive Cl-/HCO3- exchanger activity in cells overexpressing Slc4a8 or Slc4a10. Further characterization of cation-driven Cl-/HCO3- exchange demonstrated that Slc4a8 and Slc4a10 also mediate Cl- and HCO3--dependent K+ transport. Full-atom molecular dynamics simulation on the recently solved structure of Slc4a8 supports the coordination of K+ at the Na+ binding site in S1. Sequence analysis shows that the critical residues coordinating monovalent cations are conserved among mouse Slc4a8 and Slc4a10 proteins. Together, our results suggest that Slc4a8 and Slc4a10 might transport K+ in the same direction as HCO3- ions in a similar fashion to that described for Na+ transport in the rat Slc4a8 structure.
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Affiliation(s)
- Gaspar Peña-Münzenmayer
- Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Valdivia 5090000, Chile; (G.P.-M.); (N.A.); (C.S.)
- Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Valdivia 5090000, Chile
| | - Alvin T. George
- Secretory Mechanisms and Dysfunction Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Nuria Llontop
- Instituto de Fisiología, Facultad de Medicina, Universidad Austral de Chile, Valdivia 5090000, Chile; (N.L.); (J.S.)
| | - Yuliet Mazola
- Center for Bioinformatics and Molecular Simulations (CBSM), Universidad de Talca, Talca 3460000, Chile (W.G.)
| | - Natalia Apablaza
- Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Valdivia 5090000, Chile; (G.P.-M.); (N.A.); (C.S.)
| | - Carlos Spichiger
- Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Valdivia 5090000, Chile; (G.P.-M.); (N.A.); (C.S.)
| | - Sebastián Brauchi
- Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Valdivia 5090000, Chile
- Instituto de Fisiología, Facultad de Medicina, Universidad Austral de Chile, Valdivia 5090000, Chile; (N.L.); (J.S.)
| | - José Sarmiento
- Instituto de Fisiología, Facultad de Medicina, Universidad Austral de Chile, Valdivia 5090000, Chile; (N.L.); (J.S.)
| | - Leandro Zúñiga
- Centro de Nanomedicina, Diagnóstico y Desarrollo de Fármacos (ND3), Laboratorio de Fisiología Molecular, Escuela de Medicina, Universidad de Talca, Casilla, Talca 3460000, Chile;
| | - Wendy González
- Center for Bioinformatics and Molecular Simulations (CBSM), Universidad de Talca, Talca 3460000, Chile (W.G.)
- Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Talca 3460000, Chile
| | - Marcelo A. Catalán
- Instituto de Fisiología, Facultad de Medicina, Universidad Austral de Chile, Valdivia 5090000, Chile; (N.L.); (J.S.)
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2
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Axelsen TV, Olesen C, Khan D, Mohammadi A, Bouzinova EV, Nielsen CJF, Mele M, Hauerslev KR, Pedersen HL, Balling E, Vahl P, Tramm T, Christiansen PM, Boedtkjer E. Antibodies toward Na +,HCO 3--cotransporter NBCn1/SLC4A7 block net acid extrusion and cause pH-dependent growth inhibition and apoptosis in breast cancer. Br J Cancer 2024; 130:1206-1220. [PMID: 38310186 PMCID: PMC10991555 DOI: 10.1038/s41416-024-02591-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 01/09/2024] [Accepted: 01/17/2024] [Indexed: 02/05/2024] Open
Abstract
BACKGROUND Na+,HCO3--cotransporter NBCn1/Slc4a7 accelerates murine breast carcinogenesis. Lack of specific pharmacological tools previously restricted therapeutic targeting of NBCn1 and identification of NBCn1-dependent functions in human breast cancer. METHODS We develop extracellularly-targeted anti-NBCn1 antibodies, screen for functional activity on cells, and evaluate (a) mechanisms of intracellular pH regulation in human primary breast carcinomas, (b) proliferation, cell death, and tumor growth consequences of NBCn1 in triple-negative breast cancer, and (c) association of NBCn1-mediated Na+,HCO3--cotransport with human breast cancer metastasis. RESULTS We identify high-affinity (KD ≈ 0.14 nM) anti-NBCn1 antibodies that block human NBCn1-mediated Na+,HCO3--cotransport in cells, without cross-reactivity towards human NBCe1 or murine NBCn1. These anti-NBCn1 antibodies abolish Na+,HCO3--cotransport activity in freshly isolated primary organoids from human breast carcinomas and lower net acid extrusion effectively in primary breast cancer tissue from patients with macrometastases in axillary lymph nodes. Inhibitory anti-NBCn1 antibodies decelerate tumor growth in vivo by ~50% in a patient-derived xenograft model of triple-negative breast cancer and pH-dependently reduce colony formation, cause G2/M-phase cell cycle accumulation, and increase apoptosis of metastatic triple-negative breast cancer cells in vitro. CONCLUSIONS Inhibitory anti-NBCn1 antibodies block net acid extrusion in human breast cancer tissue, particularly from patients with disseminated disease, and pH-dependently limit triple-negative breast cancer growth.
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Affiliation(s)
- Trine V Axelsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Claus Olesen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Danish Khan
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Ali Mohammadi
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | | | - Marco Mele
- Department of Surgery, Randers Regional Hospital, Randers, Denmark
| | - Katrine R Hauerslev
- Department of Plastic and Breast Surgery, Aarhus University Hospital, Aarhus, Denmark
| | - Helene L Pedersen
- Department of Pathology, Randers Regional Hospital, Randers, Denmark
| | - Eva Balling
- Department of Surgery, Randers Regional Hospital, Randers, Denmark
| | - Pernille Vahl
- Department of Pathology, Aarhus University Hospital, Aarhus, Denmark
| | - Trine Tramm
- Department of Pathology, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Peer M Christiansen
- Department of Surgery, Randers Regional Hospital, Randers, Denmark
- Department of Plastic and Breast Surgery, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Ebbe Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
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3
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Holmberg SR, Sakamoto Y, Kato A, Romero MF. The role of Na +-coupled bicarbonate transporters (NCBT) in health and disease. Pflugers Arch 2024; 476:479-503. [PMID: 38536494 DOI: 10.1007/s00424-024-02937-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 04/11/2024]
Abstract
Cellular and organism survival depends upon the regulation of pH, which is regulated by highly specialized cell membrane transporters, the solute carriers (SLC) (For a comprehensive list of the solute carrier family members, see: https://www.bioparadigms.org/slc/ ). The SLC4 family of bicarbonate (HCO3-) transporters consists of ten members, sorted by their coupling to either sodium (NBCe1, NBCe2, NBCn1, NBCn2, NDCBE), chloride (AE1, AE2, AE3), or borate (BTR1). The ionic coupling of SLC4A9 (AE4) remains controversial. These SLC4 bicarbonate transporters may be controlled by cellular ionic gradients, cellular membrane voltage, and signaling molecules to maintain critical cellular and systemic pH (acid-base) balance. There are profound consequences when blood pH deviates even a small amount outside the normal range (7.35-7.45). Chiefly, Na+-coupled bicarbonate transporters (NCBT) control intracellular pH in nearly every living cell, maintaining the biological pH required for life. Additionally, NCBTs have important roles to regulate cell volume and maintain salt balance as well as absorption and secretion of acid-base equivalents. Due to their varied tissue expression, NCBTs have roles in pathophysiology, which become apparent in physiologic responses when their expression is reduced or genetically deleted. Variations in physiological pH are seen in a wide variety of conditions, from canonically acid-base related conditions to pathologies not necessarily associated with acid-base dysfunction such as cancer, glaucoma, or various neurological diseases. The membranous location of the SLC4 transporters as well as recent advances in discovering their structural biology makes them accessible and attractive as a druggable target in a disease context. The role of sodium-coupled bicarbonate transporters in such a large array of conditions illustrates the potential of treating a wide range of disease states by modifying function of these transporters, whether that be through inhibition or enhancement.
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Affiliation(s)
- Shannon R Holmberg
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN 55905, USA
- Biochemistry & Molecular Biology, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN, USA
| | - Yohei Sakamoto
- School of Life Science and Technology, Tokyo Institute of Technology, Midori-Ku, Yokohama, 226-8501, Japan
| | - Akira Kato
- School of Life Science and Technology, Tokyo Institute of Technology, Midori-Ku, Yokohama, 226-8501, Japan
| | - Michael F Romero
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN 55905, USA.
- Nephrology & Hypertension, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN, USA.
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4
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Fringuello AR, Colbourn R, Goodman JH, Michelson HB, Ling DSF, Hrabetova S. Rapid volume pulsations of the extracellular space accompany epileptiform activity in trauma-injured neocortex and depend on the sodium-bicarbonate cotransporter NBCe1. Epilepsy Res 2024; 201:107337. [PMID: 38461594 DOI: 10.1016/j.eplepsyres.2024.107337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 02/19/2024] [Accepted: 02/29/2024] [Indexed: 03/12/2024]
Abstract
Post traumatic epilepsy (PTE) is a treatment-resistant consequence of traumatic brain injury (TBI). Recently, it has been revealed that epileptiform activity in acute chemoconvulsant seizure models is accompanied by transient shrinkages of extracellular space (ECS) called rapid volume pulsations (RVPs). Shrinkage of the ECS surrounding neurons and glia may contribute to ictogenic hyperexcitability and hypersynchrony during the chronic phase of TBI. Here, we identify the phenomenon of RVPs occurring spontaneously in rat neocortex at ≥ 3 weeks after injury in the controlled cortical impact (CCI) model for PTE. We further report that blocking the electrogenic action of the astrocytic cotransporter NBCe1 with 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) eliminates both RVPs and epileptiform activity in ex-vivo CCI neocortical brain slices. We conclude that NBCe1-mediated extracellular volume shrinkage may represent a new target for therapeutic intervention in PTE.
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Affiliation(s)
- Anthony R Fringuello
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; Neural and Behavioral Science Graduate Program, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Robert Colbourn
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; Neural and Behavioral Science Graduate Program, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; Present address: Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Jeffrey H Goodman
- Department of Developmental Neurobiology, The New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA; Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Hillary B Michelson
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Douglas S F Ling
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Sabina Hrabetova
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Health Sciences University, Brooklyn, NY, USA.
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5
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Everaerts K, Thapaliya P, Pape N, Durry S, Eitelmann S, Roussa E, Ullah G, Rose CR. Inward Operation of Sodium-Bicarbonate Cotransporter 1 Promotes Astrocytic Na + Loading and Loss of ATP in Mouse Neocortex during Brief Chemical Ischemia. Cells 2023; 12:2675. [PMID: 38067105 PMCID: PMC10705779 DOI: 10.3390/cells12232675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 11/14/2023] [Accepted: 11/16/2023] [Indexed: 12/18/2023] Open
Abstract
Ischemic conditions cause an increase in the sodium concentration of astrocytes, driving the breakdown of ionic homeostasis and exacerbating cellular damage. Astrocytes express high levels of the electrogenic sodium-bicarbonate cotransporter1 (NBCe1), which couples intracellular Na+ homeostasis to regulation of pH and operates close to its reversal potential under physiological conditions. Here, we analyzed its mode of operation during transient energy deprivation via imaging astrocytic pH, Na+, and ATP in organotypic slice cultures of the mouse neocortex, complemented with patch-clamp and ion-selective microelectrode recordings and computational modeling. We found that a 2 min period of metabolic failure resulted in a transient acidosis accompanied by a Na+ increase in astrocytes. Inhibition of NBCe1 increased the acidosis while decreasing the Na+ load. Similar results were obtained when comparing ion changes in wild-type and Nbce1-deficient mice. Mathematical modeling replicated these findings and further predicted that NBCe1 activation contributes to the loss of cellular ATP under ischemic conditions, a result confirmed experimentally using FRET-based imaging of ATP. Altogether, our data demonstrate that transient energy failure stimulates the inward operation of NBCe1 in astrocytes. This causes a significant amelioration of ischemia-induced astrocytic acidification, albeit at the expense of increased Na+ influx and a decline in cellular ATP.
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Affiliation(s)
- Katharina Everaerts
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany; (K.E.); (N.P.); (S.D.); (S.E.)
| | - Pawan Thapaliya
- Department of Physics, University of South Florida, Tampa, FL 33620, USA; (P.T.); (G.U.)
| | - Nils Pape
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany; (K.E.); (N.P.); (S.D.); (S.E.)
| | - Simone Durry
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany; (K.E.); (N.P.); (S.D.); (S.E.)
| | - Sara Eitelmann
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany; (K.E.); (N.P.); (S.D.); (S.E.)
| | - Eleni Roussa
- Institute of Anatomy and Cell Biology, Department of Molecular Embryology, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Albertstrasse 17, D-79104 Freiburg, Germany;
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL 33620, USA; (P.T.); (G.U.)
| | - Christine R. Rose
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany; (K.E.); (N.P.); (S.D.); (S.E.)
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6
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Fasham J, Huebner AK, Liebmann L, Khalaf-Nazzal R, Maroofian R, Kryeziu N, Wortmann SB, Leslie JS, Ubeyratna N, Mancini GMS, van Slegtenhorst M, Wilke M, Haack TB, Shamseldin HE, Gleeson JG, Almuhaizea M, Dweikat I, Abu-Libdeh B, Daana M, Zaki MS, Wakeling MN, McGavin L, Turnpenny PD, Alkuraya FS, Houlden H, Schlattmann P, Kaila K, Crosby AH, Baple EL, Hübner CA. SLC4A10 mutation causes a neurological disorder associated with impaired GABAergic transmission. Brain 2023; 146:4547-4561. [PMID: 37459438 PMCID: PMC10629776 DOI: 10.1093/brain/awad235] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/19/2023] [Accepted: 06/06/2023] [Indexed: 11/09/2023] Open
Abstract
SLC4A10 is a plasma-membrane bound transporter that utilizes the Na+ gradient to drive cellular HCO3- uptake, thus mediating acid extrusion. In the mammalian brain, SLC4A10 is expressed in principal neurons and interneurons, as well as in epithelial cells of the choroid plexus, the organ regulating the production of CSF. Using next generation sequencing on samples from five unrelated families encompassing nine affected individuals, we show that biallelic SLC4A10 loss-of-function variants cause a clinically recognizable neurodevelopmental disorder in humans. The cardinal clinical features of the condition include hypotonia in infancy, delayed psychomotor development across all domains and intellectual impairment. Affected individuals commonly display traits associated with autistic spectrum disorder including anxiety, hyperactivity and stereotyped movements. In two cases isolated episodes of seizures were reported in the first few years of life, and a further affected child displayed bitemporal epileptogenic discharges on EEG without overt clinical seizures. While occipitofrontal circumference was reported to be normal at birth, progressive postnatal microcephaly evolved in 7 out of 10 affected individuals. Neuroradiological features included a relative preservation of brain volume compared to occipitofrontal circumference, characteristic narrow sometimes 'slit-like' lateral ventricles and corpus callosum abnormalities. Slc4a10 -/- mice, deficient for SLC4A10, also display small lateral brain ventricles and mild behavioural abnormalities including delayed habituation and alterations in the two-object novel object recognition task. Collapsed brain ventricles in both Slc4a10-/- mice and affected individuals suggest an important role of SLC4A10 in the production of the CSF. However, it is notable that despite diverse roles of the CSF in the developing and adult brain, the cortex of Slc4a10-/- mice appears grossly intact. Co-staining with synaptic markers revealed that in neurons, SLC4A10 localizes to inhibitory, but not excitatory, presynapses. These findings are supported by our functional studies, which show the release of the inhibitory neurotransmitter GABA is compromised in Slc4a10-/- mice, while the release of the excitatory neurotransmitter glutamate is preserved. Manipulation of intracellular pH partially rescues GABA release. Together our studies define a novel neurodevelopmental disorder associated with biallelic pathogenic variants in SLC4A10 and highlight the importance of further analyses of the consequences of SLC4A10 loss-of-function for brain development, synaptic transmission and network properties.
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Affiliation(s)
- James Fasham
- RILD Wellcome Wolfson Centre, University of Exeter Medical School, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX2 5DW, UK
- Peninsula Clinical Genetics Service, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX2 5DW, UK
| | - Antje K Huebner
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller Universität, 07747 Jena, Germany
| | - Lutz Liebmann
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller Universität, 07747 Jena, Germany
| | - Reham Khalaf-Nazzal
- Department of Biomedical Sciences, Faculty of Medicine, Arab American University of Palestine, Jenin, P227, Palestine
| | - Reza Maroofian
- Molecular and Clinical Sciences Institute, St. George’s University of London, London SW17 0RE, UK
| | - Nderim Kryeziu
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller Universität, 07747 Jena, Germany
| | - Saskia B Wortmann
- University Children’s Hospital, Salzburger Landeskliniken (SALK) and Paracelsus Medical University (PMU), 5020 Salzburg, Austria
- Amalia Children’s Hospital, Radboudumc, 6525 GA Nijmegen, The Netherlands
- Institute of Human Genetics, Technische Universität München, 80333 Munich, Germany
| | - Joseph S Leslie
- RILD Wellcome Wolfson Centre, University of Exeter Medical School, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX2 5DW, UK
| | - Nishanka Ubeyratna
- RILD Wellcome Wolfson Centre, University of Exeter Medical School, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX2 5DW, UK
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus Medical Center, 3015 GD Rotterdam, The Netherlands
| | | | - Martina Wilke
- Department of Clinical Genetics, Erasmus Medical Center, 3015 GD Rotterdam, The Netherlands
| | - Tobias B Haack
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, 72076 Tübingen, Germany
| | - Hanan E Shamseldin
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh 11564, Saudi Arabia
| | - Joseph G Gleeson
- Rady Children’s Institute for Genomic Medicine, San Diego, CA 92123, USA
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Mohamed Almuhaizea
- Department of Neuroscience, King Faisal Specialist Hospital and Research Center, Riyadh 11564, Saudi Arabia
| | - Imad Dweikat
- Department of Biomedical Sciences, Faculty of Medicine, Arab American University of Palestine, Jenin, P227, Palestine
| | - Bassam Abu-Libdeh
- Department of Pediatrics and Genetics, Makassed Hospital and Al-Quds University, East Jerusalem, 95908, Palestine
| | - Muhannad Daana
- Department of Pediatrics, Arab Women’s Union Hospital, Nablus, P400, Palestine
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Dokki, Cairo 12622, Egypt
| | - Matthew N Wakeling
- RILD Wellcome Wolfson Centre, University of Exeter Medical School, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX2 5DW, UK
| | - Lucy McGavin
- Department of Radiology, Derriford Hospital, Plymouth PL6 8DH, UK
| | - Peter D Turnpenny
- RILD Wellcome Wolfson Centre, University of Exeter Medical School, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX2 5DW, UK
- Peninsula Clinical Genetics Service, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX2 5DW, UK
| | - Fowzan S Alkuraya
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh 11564, Saudi Arabia
| | - Henry Houlden
- Molecular and Clinical Sciences Institute, St. George’s University of London, London SW17 0RE, UK
| | - Peter Schlattmann
- Institute for Medical Statistics, Computer Science and Data Science, Jena University Hospital, 07747 Jena, Germany
| | - Kai Kaila
- Molecular and Integrative Biosciences, University of Helsinki, 00014 Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, 00014 Helsinki, Finland
| | - Andrew H Crosby
- RILD Wellcome Wolfson Centre, University of Exeter Medical School, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX2 5DW, UK
| | - Emma L Baple
- RILD Wellcome Wolfson Centre, University of Exeter Medical School, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX2 5DW, UK
- Peninsula Clinical Genetics Service, Royal Devon University Healthcare NHS Foundation Trust, Exeter EX2 5DW, UK
| | - Christian A Hübner
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller Universität, 07747 Jena, Germany
- Center for Rare Diseases, Jena University Hospital, Friedrich Schiller Universität, 07747 Jena, Germany
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7
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Li K, Gonye EC, Stornetta RL, Bayliss CB, Yi G, Stornetta DS, Baca SM, Abbott SB, Guyenet PG, Bayliss DA. The astrocytic Na + -HCO 3 - cotransporter, NBCe1, is dispensable for respiratory chemosensitivity. J Physiol 2023; 601:3667-3686. [PMID: 37384821 PMCID: PMC10528273 DOI: 10.1113/jp284960] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 06/02/2023] [Indexed: 07/01/2023] Open
Abstract
The interoceptive homeostatic mechanism that controls breathing, blood gases and acid-base balance in response to changes in CO2 /H+ is exquisitely sensitive, with convergent roles proposed for chemosensory brainstem neurons in the retrotrapezoid nucleus (RTN) and their supporting glial cells. For astrocytes, a central role for NBCe1, a Na+ -HCO3 - cotransporter encoded by Slc4a4, has been envisaged in multiple mechanistic models (i.e. underlying enhanced CO2 -induced local extracellular acidification or purinergic signalling). We tested these NBCe1-centric models by using conditional knockout mice in which Slc4a4 was deleted from astrocytes. In GFAP-Cre;Slc4a4fl/fl mice we found diminished expression of Slc4a4 in RTN astrocytes by comparison to control littermates, and a concomitant reduction in NBCe1-mediated current. Despite disrupted NBCe1 function in RTN-adjacent astrocytes from these conditional knockout mice, CO2 -induced activation of RTN neurons or astrocytes in vitro and in vivo, and CO2 -stimulated breathing, were indistinguishable from NBCe1-intact littermates; hypoxia-stimulated breathing and sighs were likewise unaffected. We obtained a more widespread deletion of NBCe1 in brainstem astrocytes by using tamoxifen-treated Aldh1l1-Cre/ERT2;Slc4a4fl/fl mice. Again, there was no difference in effects of CO2 or hypoxia on breathing or on neuron/astrocyte activation in NBCe1-deleted mice. These data indicate that astrocytic NBCe1 is not required for the respiratory responses to these chemoreceptor stimuli in mice, and that any physiologically relevant astrocytic contributions must involve NBCe1-independent mechanisms. KEY POINTS: The electrogenic NBCe1 transporter is proposed to mediate local astrocytic CO2 /H+ sensing that enables excitatory modulation of nearby retrotrapezoid nucleus (RTN) neurons to support chemosensory control of breathing. We used two different Cre mouse lines for cell-specific and/or temporally regulated deletion of the NBCe1 gene (Slc4a4) in astrocytes to test this hypothesis. In both mouse lines, Slc4a4 was depleted from RTN-associated astrocytes but CO2 -induced Fos expression (i.e. cell activation) in RTN neurons and local astrocytes was intact. Likewise, respiratory chemoreflexes evoked by changes in CO2 or O2 were unaffected by loss of astrocytic Slc4a4. These data do not support the previously proposed role for NBCe1 in respiratory chemosensitivity mediated by astrocytes.
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Affiliation(s)
- Keyong Li
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Elizabeth C. Gonye
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Ruth L. Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | | | - Grace Yi
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Daniel S. Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Serapio M. Baca
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Stephen B.G. Abbott
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Patrice G. Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
| | - Douglas A. Bayliss
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA, 22908
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8
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Lee SK, Occhipinti R, Moss FJ, Parker MD, Grichtchenko II, Boron WF. Distinguishing among HCO 3- , CO 3= , and H + as Substrates of Proteins That Appear To Be "Bicarbonate" Transporters. J Am Soc Nephrol 2023; 34:40-54. [PMID: 36288904 PMCID: PMC10103014 DOI: 10.1681/asn.2022030289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 07/23/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Differentiating among HCO 3- , CO 3= , and H + movements across membranes has long seemed impossible. We now seek to discriminate unambiguously among three alternate mechanisms: the inward flux of 2 HCO 3- (mechanism 1), the inward flux of 1 CO 3= (mechanism 2), and the CO 2 /HCO 3- -stimulated outward flux of 2 H + (mechanism 3). METHODS As a test case, we use electrophysiology and heterologous expression in Xenopus oocytes to examine SLC4 family members that appear to transport "bicarbonate" ("HCO 3- "). RESULTS First, we note that cell-surface carbonic anhydrase should catalyze the forward reaction CO 2 +OH - →HCO 3- if HCO 3- is the substrate; if it is not, the reverse reaction should occur. Monitoring changes in cell-surface pH ( Δ pH S ) with or without cell-surface carbonic anhydrase, we find that the presumed Cl-"HCO 3 " exchanger AE1 (SLC4A1) does indeed transport HCO 3- (mechanism 1) as long supposed, whereas the electrogenic Na/"HCO 3 " cotransporter NBCe1 (SLC4A4) and the electroneutral Na + -driven Cl-"HCO 3 " exchanger NDCBE (SLC4A8) do not. Second, we use mathematical simulations to show that each of the three mechanisms generates unique quantities of H + at the cell surface (measured as Δ pH S ) per charge transported (measured as change in membrane current, ΔIm ). Calibrating ΔpH S /Δ Im in oocytes expressing the H + channel H V 1, we find that our NBCe1 data align closely with predictions of CO 3= transport (mechanism 2), while ruling out HCO 3- (mechanism 1) and CO 2 /HCO 3- -stimulated H + transport (mechanism 3). CONCLUSIONS Our surface chemistry approach makes it possible for the first time to distinguish among HCO 3- , CO 3= , and H + fluxes, thereby providing insight into molecular actions of clinically relevant acid-base transporters and carbonic-anhydrase inhibitors.
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Affiliation(s)
- Seong-Ki Lee
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Rossana Occhipinti
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Fraser J. Moss
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Mark D. Parker
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
- Department of Physiology and Biophysics, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York
| | | | - Walter F. Boron
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio
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9
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Verlander JW, Lee HW, Wall SM, Harris AN, Weiner ID. The proximal tubule through an NBCe1-dependent mechanism regulates collecting duct phenotypic and remodeling responses to acidosis. Am J Physiol Renal Physiol 2023; 324:F12-F29. [PMID: 36264886 PMCID: PMC9762982 DOI: 10.1152/ajprenal.00175.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/12/2022] [Accepted: 10/13/2022] [Indexed: 02/04/2023] Open
Abstract
The renal response to acid-base disturbances involves phenotypic and remodeling changes in the collecting duct. This study examines whether the proximal tubule controls these responses. We examined mice with genetic deletion of proteins present only in the proximal tubule, either the A variant or both A and B variants of isoform 1 of the electrogenic Na+-bicarbonate cotransporter (NBCe1). Both knockout (KO) mice have spontaneous metabolic acidosis. We then determined the collecting duct phenotypic responses to this acidosis and the remodeling responses to exogenous acid loading. Despite the spontaneous acidosis in NBCe1-A KO mice, type A intercalated cells in the inner stripe of the outer medullary collecting duct (OMCDis) exhibited decreased height and reduced expression of H+-ATPase, anion exchanger 1, Rhesus B glycoprotein, and Rhesus C glycoprotein. Combined kidney-specific NBCe1-A/B deletion induced similar changes. Ultrastructural imaging showed decreased apical plasma membrane and increased vesicular H+-ATPase in OMCDis type A intercalated cell in NBCe1-A KO mice. Next, we examined the collecting duct remodeling response to acidosis. In wild-type mice, acid loading increased the proportion of type A intercalated cells in the connecting tubule (CNT) and OMCDis, and it decreased the proportion of non-A, non-B intercalated cells in the connecting tubule, and type B intercalated cells in the cortical collecting duct (CCD). These changes were absent in NBCe1-A KO mice. We conclude that the collecting duct phenotypic and remodeling responses depend on proximal tubule-dependent signaling mechanisms blocked by constitutive deletion of proximal tubule NBCe1 proteins.NEW & NOTEWORTHY This study shows that the proximal tubule regulates collecting duct phenotypic and remodeling responses to acidosis.
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Affiliation(s)
- Jill W Verlander
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Susan M Wall
- Renal Division, Emory University, Atlanta, Georgia
| | - Autumn N Harris
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
- Deparment of Small Animal Clinical Science, University of Florida College of Veterinary Medicine, Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
- Nephrology and Hypertension Section, Gainesville Veterans Administration Medical Center, Gainesville, Florida
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10
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Wilson AD, Richards MA, Curtis MK, Gunadasa-Rohling M, Monterisi S, Loonat AA, Miller JJ, Ball V, Lewis A, Tyler DJ, Moshnikova A, Andreev OA, Reshetnyak YK, Carr C, Swietach P. Acidic environments trigger intracellular H+-sensing FAK proteins to re-balance sarcolemmal acid-base transporters and auto-regulate cardiomyocyte pH. Cardiovasc Res 2022; 118:2946-2959. [PMID: 34897412 PMCID: PMC9648823 DOI: 10.1093/cvr/cvab364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 12/08/2021] [Indexed: 11/12/2022] Open
Abstract
AIMS In cardiomyocytes, acute disturbances to intracellular pH (pHi) are promptly corrected by a system of finely tuned sarcolemmal acid-base transporters. However, these fluxes become thermodynamically re-balanced in acidic environments, which inadvertently causes their set-point pHi to fall outside the physiological range. It is unclear whether an adaptive mechanism exists to correct this thermodynamic challenge, and return pHi to normal. METHODS AND RESULTS Following left ventricle cryo-damage, a diffuse pattern of low extracellular pH (pHe) was detected by acid-sensing pHLIP. Despite this, pHi measured in the beating heart (13C NMR) was normal. Myocytes had adapted to their acidic environment by reducing Cl-/HCO3- exchange (CBE)-dependent acid-loading and increasing Na+/H+ exchange (NHE1)-dependent acid-extrusion, as measured by fluorescence (cSNARF1). The outcome of this adaptation on pHi is revealed as a cytoplasmic alkalinization when cells are superfused at physiological pHe. Conversely, mice given oral bicarbonate (to improve systemic buffering) had reduced myocardial NHE1 expression, consistent with a needs-dependent expression of pHi-regulatory transporters. The response to sustained acidity could be replicated in vitro using neonatal ventricular myocytes incubated at low pHe for 48 h. The adaptive increase in NHE1 and decrease in CBE activities was linked to Slc9a1 (NHE1) up-regulation and Slc4a2 (AE2) down-regulation. This response was triggered by intracellular H+ ions because it persisted in the absence of CO2/HCO3- and became ablated when acidic incubation media had lower chloride, a solution manoeuvre that reduces the extent of pHi-decrease. Pharmacological inhibition of FAK-family non-receptor kinases, previously characterized as pH-sensors, ablated this pHi autoregulation. In support of a pHi-sensing role, FAK protein Pyk2 (auto)phosphorylation was reduced within minutes of exposure to acidity, ahead of adaptive changes to pHi control. CONCLUSIONS Cardiomyocytes fine-tune the expression of pHi-regulators so that pHi is at least 7.0. This autoregulatory feedback mechanism defines physiological pHi and protects it during pHe vulnerabilities.
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Affiliation(s)
- Abigail D Wilson
- Department of Physiology, Anatomy & Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Mark A Richards
- Department of Physiology, Anatomy & Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - M Kate Curtis
- Department of Physiology, Anatomy & Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Mala Gunadasa-Rohling
- Department of Physiology, Anatomy & Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Stefania Monterisi
- Department of Physiology, Anatomy & Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Aminah A Loonat
- Department of Physiology, Anatomy & Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Jack J Miller
- Department of Physiology, Anatomy & Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Radcliffe Department of Medicine, Level 0, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
| | - Vicky Ball
- Department of Physiology, Anatomy & Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Andrew Lewis
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Radcliffe Department of Medicine, Level 0, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
| | - Damian J Tyler
- Department of Physiology, Anatomy & Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Radcliffe Department of Medicine, Level 0, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
| | - Anna Moshnikova
- Physics Department, University of Rhode Island, 2 Lippitt Rd, Kingston, RI 02881, USA
| | - Oleg A Andreev
- Physics Department, University of Rhode Island, 2 Lippitt Rd, Kingston, RI 02881, USA
| | - Yana K Reshetnyak
- Physics Department, University of Rhode Island, 2 Lippitt Rd, Kingston, RI 02881, USA
| | - Carolyn Carr
- Department of Physiology, Anatomy & Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Pawel Swietach
- Department of Physiology, Anatomy & Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
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11
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Ali ES, Lipońska A, O'Hara BP, Amici DR, Torno MD, Gao P, Asara JM, Yap MNF, Mendillo ML, Ben-Sahra I. The mTORC1-SLC4A7 axis stimulates bicarbonate import to enhance de novo nucleotide synthesis. Mol Cell 2022; 82:3284-3298.e7. [PMID: 35772404 PMCID: PMC9444906 DOI: 10.1016/j.molcel.2022.06.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 05/15/2022] [Accepted: 06/07/2022] [Indexed: 12/12/2022]
Abstract
Bicarbonate (HCO3-) ions maintain pH homeostasis in eukaryotic cells and serve as a carbonyl donor to support cellular metabolism. However, whether the abundance of HCO3- is regulated or harnessed to promote cell growth is unknown. The mechanistic target of rapamycin complex 1 (mTORC1) adjusts cellular metabolism to support biomass production and cell growth. We find that mTORC1 stimulates the intracellular transport of HCO3- to promote nucleotide synthesis through the selective translational regulation of the sodium bicarbonate cotransporter SLC4A7. Downstream of mTORC1, SLC4A7 mRNA translation required the S6K-dependent phosphorylation of the translation factor eIF4B. In mTORC1-driven cells, loss of SLC4A7 resulted in reduced cell and tumor growth and decreased flux through de novo purine and pyrimidine synthesis in human cells and tumors without altering the intracellular pH. Thus, mTORC1 signaling, through the control of SLC4A7 expression, harnesses environmental bicarbonate to promote anabolic metabolism, cell biomass, and growth.
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Affiliation(s)
- Eunus S Ali
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Anna Lipońska
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Brendan P O'Hara
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - David R Amici
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Michael D Torno
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Peng Gao
- Metabolomics Core Facility, Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - John M Asara
- Mass Spectrometry Core, Beth Israel Deaconess Medical Center, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Mee-Ngan F Yap
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Marc L Mendillo
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
| | - Issam Ben-Sahra
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA.
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12
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Giannaki M, Ruf DE, Pfeifer E, Everaerts K, Heiland DH, Schnell O, Rose CR, Roussa E. Cell-Type Dependent Regulation of the Electrogenic Na+/HCO3- Cotransporter 1 (NBCe1) by Hypoxia and Acidosis in Glioblastoma. Int J Mol Sci 2022; 23:ijms23168975. [PMID: 36012235 PMCID: PMC9408864 DOI: 10.3390/ijms23168975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 08/05/2022] [Accepted: 08/08/2022] [Indexed: 11/16/2022] Open
Abstract
Glioblastoma multiforme (GBM) is the most common and malignant brain tumour. It is characterised by transcriptionally distinct cell populations. In tumour cells, physiological pH gradients between the intracellular and extracellular compartments are reversed, compared to non-cancer cells. Intracellular pH in tumour cells is alkaline, whereas extracellular pH is acidic. Consequently, the function and/or expression of pH regulating transporters might be altered. Here, we investigated protein expression and regulation of the electrogenic sodium/bicarbonate cotransporter 1 (NBCe1) in mesenchymal (MES)-like hypoxia-dependent and -independent cells, as well as in astrocyte-like glioblastoma cells following chemical hypoxia, acidosis and elucidated putative underlying molecular pathways. Immunoblotting, immunocytochemistry, and intracellular pH recording with the H+-sensitive dye 2′,7′-bis-(carboxyethyl)-5-(and-6)-carboxyfluorescein were applied. The results show NBCe1 protein abundance and active NBCe1 transport. Hypoxia upregulated NBCe1 protein and activity in MES-like hypoxia-dependent GBM cells. This effect was positively correlated with HIF-1α protein levels, was mediated by TGF-β signalling, and was prevented by extracellular acidosis. In MES-like hypoxia-independent GBM cells, acidosis (but not hypoxia) regulated NBCe1 activity in an HIF-1α-independent manner. These results demonstrate a cell-specific adaptation of NBCe1 expression and activity to the microenvironment challenge of hypoxia and acidosis that depends on their transcriptional signature in GBM.
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Affiliation(s)
- Marina Giannaki
- Department of Molecular Embryology, Faculty of Medicine, Institute of Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Albertstrasse 17, D-79104 Freiburg, Germany
| | - Debora E. Ruf
- Department of Molecular Embryology, Faculty of Medicine, Institute of Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Albertstrasse 17, D-79104 Freiburg, Germany
| | - Emilie Pfeifer
- Department of Molecular Embryology, Faculty of Medicine, Institute of Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Albertstrasse 17, D-79104 Freiburg, Germany
| | - Katharina Everaerts
- Institute of Neurobiology, Heinrich Heine University, D-40225 Düsseldorf, Germany
| | - Dieter H. Heiland
- Department of Neurosurgery, Faculty of Medicine, Medical Center, University of Freiburg, D-79106 Freiburg, Germany
- Microenvironment and Immunology Research Laboratory, Medical Center, University of Freiburg, D-79106 Freiburg, Germany
| | - Oliver Schnell
- Department of Neurosurgery, Faculty of Medicine, Medical Center, University of Freiburg, D-79106 Freiburg, Germany
| | - Christine R. Rose
- Institute of Neurobiology, Heinrich Heine University, D-40225 Düsseldorf, Germany
| | - Eleni Roussa
- Department of Molecular Embryology, Faculty of Medicine, Institute of Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Albertstrasse 17, D-79104 Freiburg, Germany
- Correspondence: ; Tel.: +49-761-203-5114
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13
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Korsós MM, Bellák T, Becskeházi E, Gál E, Veréb Z, Hegyi P, Venglovecz V. Mouse organoid culture is a suitable model to study esophageal ion transport mechanisms. Am J Physiol Cell Physiol 2021; 321:C798-C811. [PMID: 34524930 DOI: 10.1152/ajpcell.00295.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 09/08/2021] [Indexed: 11/22/2022]
Abstract
Altered esophageal ion transport mechanisms play a key role in inflammatory and cancerous diseases of the esophagus, but epithelial ion processes have been less studied in the esophagus because of the lack of a suitable experimental model. In this study, we generated three-dimensional (3D) esophageal organoids (EOs) from two different mouse strains and characterized the ion transport processes of the EOs. EOs form a cell-filled structure with a diameter of 250-300 µm and were generated from epithelial stem cells as shown by FACS analysis. Using conventional PCR and immunostaining, the presence of Slc26a6 Cl-/HCO3- anion exchanger (AE), Na+/H+ exchanger (NHE), Na+/HCO3- cotransporter (NBC), cystic fibrosis transmembrane conductance regulator (CFTR), and anoctamin 1 Cl- channels was detected in EOs. Microfluorimetric techniques revealed high NHE, AE, and NBC activities, whereas that of CFTR was relatively low. In addition, inhibition of CFTR led to functional interactions between the major acid-base transporters and CFTR. We conclude that EOs provide a relevant and suitable model system for studying the ion transport mechanisms of esophageal epithelial cells, and they can be also used as preclinical tools to assess the effectiveness of novel therapeutic compounds in esophageal diseases associated with altered ion transport processes.
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Affiliation(s)
| | - Tamás Bellák
- Department of Anatomy, Histology and Embryology, University of Szeged, Szeged, Hungary
- BioTalentum Ltd., Gödöllő, Hungary
| | - Eszter Becskeházi
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Eleonóra Gál
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Zoltán Veréb
- Regenerative Medicine and Cellular Pharmacology Research Laboratory, Department of Dermatology and Allergology, University of Szeged, Szeged, Hungary
| | - Péter Hegyi
- First Department of Medicine, University of Szeged, Szeged, Hungary
- Szentágothai Research Centre, Institute for Translational Medicine, Medical School, University of Pécs, Pécs, Hungary
- Division of Gastroenterology, First Department of Medicine, Medical School, University of Pécs, Pécs, Hungary
| | - Viktória Venglovecz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
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14
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Harris AN, Castro RA, Lee HW, Verlander JW, Weiner ID. Role of the renal androgen receptor in sex differences in ammonia metabolism. Am J Physiol Renal Physiol 2021; 321:F629-F644. [PMID: 34605272 PMCID: PMC8616601 DOI: 10.1152/ajprenal.00260.2021] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 11/22/2022] Open
Abstract
There are sex differences in renal ammonia metabolism and structure, many of which are mediated by testosterone. The goal of the present study was to determine the role of renal expression of testosterone's canonical receptor, androgen receptor (AR), in these sexual dimorphisms. We studied mice with kidney-specific AR deletion [KS-AR-knockout (KO)] generated using Cre/loxP techniques; control mice were Cre-negative littermates (wild type). In male but not female mice, KS-AR-KO increased ammonia excretion, which eliminated sex differences. Although renal structural size typically parallel ammonia excretion, KS-AR-KO decreased kidney size, cortical proximal tubule volume density, and cortical proximal tubule cell height in males-neither were altered in females and collecting duct volume density was unaltered in both sexes. Analysis of key protein involved in ammonia handling showed in male mice that KS-AR-KO increased both phosphoenolpyruvate carboxykinase (PEPCK) and Na+-K+-2Cl- cotransporter (NKCC2) expression and decreased Na+/H+ exchanger isoform 3 (NHE3) and electrogenic Na+-bicarbonate cotransporter 1 (NBCe1)-A expression. In female mice, KS-AR-KO did not alter these parameters. These effects occurred even though KS-AR-KO did not alter plasma testosterone, food intake, or serum Na+, K+, or [Formula: see text] significantly in either sex. In conclusion, AR-dependent signaling pathways in male, but not female, kidneys regulate PEPCK and NKCC2 expression and lead to the sexual differences in ammonia excretion. Opposing effects on NHE3 and NBCe1-A expression likely limit the magnitude of ammonia excretion changes. As AR is not present in the thick ascending limb, the effect of KS-AR-KO on NKCC2 expression is indirect. Finally, AR mediates the greater kidney size and proximal tubule volume density in male compared with female mice.NEW & NOTEWORTHY Sexual dimorphisms in ammonia metabolism involve androgen receptor (AR)-dependent signaling pathways in male, but not female, kidneys that lead to altered proximal tubule (PT), phosphoenolpyruvate carboxykinase, and thick ascending limb Na+-K+-2Cl- cotransporter expression. Adaptive responses in Na+/H+ exchanger 3 and electrogenic Na+-bicarbonate cotransporter 1-A expression limit the magnitude of the effect on ammonia excretion. Finally, the greater kidney size and PT volume density in male mice is the result of PT androgen signaling through AR.
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Affiliation(s)
- Autumn N Harris
- Department of Small Animal Clinical Science, University of Florida College of Veterinary Medicine, Gainesville, Florida
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Rebeca A Castro
- Department of Small Animal Clinical Science, University of Florida College of Veterinary Medicine, Gainesville, Florida
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
- Nephrology and Hypertension Section, Gainesville Veterans Administration Medical Center, Gainesville, Florida
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15
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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: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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16
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Abehsera S, Bentov S, Li X, Weil S, Manor R, Sagi S, Li S, Li F, Khalaila I, Aflalo ED, Sagi A. Genes encoding putative bicarbonate transporters as a missing molecular link between molt and mineralization in crustaceans. Sci Rep 2021; 11:11722. [PMID: 34083647 PMCID: PMC8175698 DOI: 10.1038/s41598-021-91155-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 05/17/2021] [Indexed: 01/08/2023] Open
Abstract
During their life, crustaceans undergo several molts, which if theoretically compared to the human body would be equivalent to replacing all bones at a single event. Such a dramatic repetitive event is coupled to unique molecular mechanisms of mineralization so far mostly unknown. Unlike human bone mineralized with calcium phosphate, the crustacean exoskeleton is mineralized mainly by calcium carbonate. Crustacean growth thus necessitates well-timed mobilization of bicarbonate to specific extracellular sites of biomineralization at distinct molt cycle stages. Here, by looking at the crayfish Cherax quadricarinatus at different molting stages, we suggest that the mechanisms of bicarbonate ion transport for mineralization in crustaceans involve the SLC4 family of transporters and that these proteins play a key role in the tight coupling between molt cycle events and mineral deposition. This discovery of putative bicarbonate transporters in a pancrustacean with functional genomic evidence from genes encoding the SLC4 family-mostly known for their role in pH control-is discussed in the context of the evolution of calcium carbonate biomineralization.
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Affiliation(s)
- Shai Abehsera
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, 8410501, Beer Sheva, Israel
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Shmuel Bentov
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, 8410501, Beer Sheva, Israel
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Xuguang Li
- Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing, People's Republic of China
| | - Simy Weil
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, 8410501, Beer Sheva, Israel
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Rivka Manor
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, 8410501, Beer Sheva, Israel
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Shahar Sagi
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, 8410501, Beer Sheva, Israel
| | - Shihao Li
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, People's Republic of China
| | - Fuhua Li
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, People's Republic of China
| | - Isam Khalaila
- Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Eliahu D Aflalo
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, 8410501, Beer Sheva, Israel
- Department of Life Sciences, Achva Academic College, Arugot, Israel
| | - Amir Sagi
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, 8410501, Beer Sheva, Israel.
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
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17
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Giannaki M, Schrödl-Häußel M, Khakipoor S, Kirsch M, Roussa E. STAT3-dependent regulation of the electrogenic Na +/ HCO 3- cotransporter 1 (NBCe1) functional expression in cortical astrocytes. J Cell Physiol 2021; 236:2036-2050. [PMID: 32761631 DOI: 10.1002/jcp.29990] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/03/2020] [Accepted: 07/21/2020] [Indexed: 01/10/2023]
Abstract
The electrogenic Na+ /HCO3- cotransporter (NBCe1) in astrocytes is crucial in regulation of acid-base homeostasis in the brain. Since many pathophysiological conditions in the brain have been associated with pH shifts we exposed primary mouse cortical and hippocampal astrocytes to prolonged low or high extracellular pH (pHo ) at constant extracellular bicarbonate concentration and investigated activation of astrocytes and regulation of NBCe1 by immunoblotting, biotinylation of surface proteins, and intracellular H+ recordings. High pHo at constant extracellular bicarbonate caused upregulation of NBCe1 protein, surface expression and activity via upregulation of the astrocytic activation markers signal transducer and activator of transcription 3 (STAT3) signaling and glial fibrillary acidic protein expression. High pHo -induced increased NBCe1 protein expression was prevented in astrocytes from Stat3flox/flox ::GfapCre/+ mice. In vitro, basal and high pHo -induced increased NBCe1 functional expression was impaired following inhibition of STAT3 phosphorylation. These results provide a novel regulation mode of NBCe1 protein and activity, highlight the importance of astrocyte reactivity on regulation of NBCe1 and implicate roles for NBCe1 in altering/modulating extracellular pH during development as well as of the microenvironment at sites of brain injuries and other pathophysiological conditions.
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Affiliation(s)
- Marina Giannaki
- Department of Molecular Embryology, Medical Faculty, Institute of Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Magdalena Schrödl-Häußel
- Department of Molecular Embryology, Medical Faculty, Institute of Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Shokoufeh Khakipoor
- Department of Molecular Embryology, Medical Faculty, Institute of Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Matthias Kirsch
- Department of Neuroanatomy, Medical Faculty, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | - Eleni Roussa
- Department of Molecular Embryology, Medical Faculty, Institute of Anatomy and Cell Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
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18
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Theparambil SM, Hosford PS, Ruminot I, Kopach O, Reynolds JR, Sandoval PY, Rusakov DA, Barros LF, Gourine AV. Astrocytes regulate brain extracellular pH via a neuronal activity-dependent bicarbonate shuttle. Nat Commun 2020; 11:5073. [PMID: 33033238 PMCID: PMC7545092 DOI: 10.1038/s41467-020-18756-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 09/09/2020] [Indexed: 12/19/2022] Open
Abstract
Brain cells continuously produce and release protons into the extracellular space, with the rate of acid production corresponding to the levels of neuronal activity and metabolism. Efficient buffering and removal of excess H+ is essential for brain function, not least because all the electrogenic and biochemical machinery of synaptic transmission is highly sensitive to changes in pH. Here, we describe an astroglial mechanism that contributes to the protection of the brain milieu from acidification. In vivo and in vitro experiments conducted in rodent models show that at least one third of all astrocytes release bicarbonate to buffer extracellular H+ loads associated with increases in neuronal activity. The underlying signalling mechanism involves activity-dependent release of ATP triggering bicarbonate secretion by astrocytes via activation of metabotropic P2Y1 receptors, recruitment of phospholipase C, release of Ca2+ from the internal stores, and facilitated outward HCO3- transport by the electrogenic sodium bicarbonate cotransporter 1, NBCe1. These results show that astrocytes maintain local brain extracellular pH homeostasis via a neuronal activity-dependent release of bicarbonate. The data provide evidence of another important metabolic housekeeping function of these glial cells.
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Affiliation(s)
- Shefeeq M Theparambil
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Patrick S Hosford
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Iván Ruminot
- Centro de Estudios Científicos (CECs), Valdivia, Chile
| | - Olga Kopach
- Institute of Neurology, University College London, London, UK
| | | | | | | | | | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, UK.
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19
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Sui N, Huang F, Liu LN. Photosynthesis in Phytoplankton: Insights from the Newly Discovered Biological Inorganic Carbon Pumps. Mol Plant 2020; 13:949-951. [PMID: 32416266 DOI: 10.1016/j.molp.2020.05.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/25/2020] [Accepted: 05/07/2020] [Indexed: 05/11/2023]
Affiliation(s)
- Na Sui
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan 250014, China; Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Fang Huang
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
| | - Lu-Ning Liu
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK; College of Marine Life Sciences, and Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao 266003, China.
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20
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Uehara S, Sei A, Sada M, Ito-Inaba Y, Inaba T. Installation of authentic BicA and SbtA proteins to the chloroplast envelope membrane is achieved by the proteolytic cleavage of chimeric proteins in Arabidopsis. Sci Rep 2020; 10:2353. [PMID: 32047175 PMCID: PMC7012931 DOI: 10.1038/s41598-020-59190-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 01/24/2020] [Indexed: 11/09/2022] Open
Abstract
To improve the photosynthetic performance of C3 plants, installing cyanobacterial bicarbonate transporters to the chloroplast inner envelope membrane (IEM) has been proposed for years. In our previous study, we successfully introduced chimeric cyanobacterial sodium-dependent bicarbonate transporters, BicA or SbtA, to the chloroplast IEM of Arabidopsis. However, the installation of authentic BicA and SbtA to the chloroplast IEM has not been achieved yet. In this study, we examined whether or not tobacco etch virus (TEV) protease targeted within chloroplasts can cleave chimeric proteins and produce authentic bicarbonate transporters. To this end, we constructed a TEV protease that carried the transit peptide and expressed it with chimeric BicA or SbtA proteins containing a TEV cleavage site in planta. Chimeric proteins were cleaved only when the TEV protease was co-expressed. The authentic forms of hemagglutinin-tagged BicA and SbtA were detected in the chloroplast IEM. In addition, cleavage of chimeric proteins at the TEV recognition site seemed to occur after the targeting of chimeric proteins to the chloroplast IEM. We conclude that the cleavage of chimeric proteins within chloroplasts is an efficient way to install authentic bicarbonate transporters to the chloroplast IEM. Furthermore, a similar approach can be applied to other bacterial plasma membrane proteins.
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Affiliation(s)
- Susumu Uehara
- Department of Agricultural and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki, 889-2192, Japan
| | - Ayane Sei
- Department of Agricultural and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki, 889-2192, Japan
| | - Misaki Sada
- Department of Agricultural and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki, 889-2192, Japan
| | - Yasuko Ito-Inaba
- Department of Agricultural and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki, 889-2192, Japan
| | - Takehito Inaba
- Department of Agricultural and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki, 889-2192, Japan.
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21
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Wang C, Sun B, Zhang X, Huang X, Zhang M, Guo H, Chen X, Huang F, Chen T, Mi H, Yu F, Liu LN, Zhang P. Structural mechanism of the active bicarbonate transporter from cyanobacteria. Nat Plants 2019; 5:1184-1193. [PMID: 31712753 DOI: 10.1038/s41477-019-0538-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Accepted: 09/27/2019] [Indexed: 05/11/2023]
Abstract
Bicarbonate transporters play essential roles in pH homeostasis in mammals and photosynthesis in aquatic photoautotrophs. A number of bicarbonate transporters have been characterized, among which is BicA-a low-affinity, high-flux SLC26-family bicarbonate transporter involved in cyanobacterial CO2-concentrating mechanisms (CCMs) that accumulate CO2 and improve photosynthetic carbon fixation. Here, we report the three-dimensional structure of BicA from Synechocystis sp. PCC6803. Crystal structures of the transmembrane domain (BicATM) and the cytoplasmic STAS domain (BicASTAS) of BicA were solved. BicATM was captured in an inward-facing HCO3--bound conformation and adopts a '7+7' fold monomer. HCO3- binds to a cytoplasm-facing hydrophilic pocket within the membrane. BicASTAS is assembled as a compact homodimer structure and is required for the dimerization of BicA. The dimeric structure of BicA was further analysed using cryo-electron microscopy and physiological analysis of the full-length BicA, and may represent the physiological unit of SLC26-family transporters. Comparing the BicATM structure with the outward-facing transmembrane domain structures of other bicarbonate transporters suggests an elevator transport mechanism that is applicable to the SLC26/4 family of sodium-dependent bicarbonate transporters. This study advances our knowledge of the structures and functions of cyanobacterial bicarbonate transporters, and will inform strategies for bioengineering functional BicA in heterologous organisms to increase assimilation of CO2.
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Affiliation(s)
- Chengcheng Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Bo Sun
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
| | - Xue Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiaowei Huang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Minhua Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Hui Guo
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xin Chen
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Fang Huang
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Taiyu Chen
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Hualing Mi
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Fang Yu
- Shanghai Key Laboratory of Plant Molecualr Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Lu-Ning Liu
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Peng Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
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22
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Lorenzo-Pouso AI, Pérez-Sayáns M, Rodríguez-Zorrilla S, Chamorro-Petronacci C, García-García A. Dissecting the Proton Transport Pathway in Oral Squamous Cell Carcinoma: State of the Art and Theranostics Implications. Int J Mol Sci 2019; 20:ijms20174222. [PMID: 31470498 PMCID: PMC6747091 DOI: 10.3390/ijms20174222] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 08/27/2019] [Accepted: 08/28/2019] [Indexed: 12/12/2022] Open
Abstract
Cancer cells overexpress proton exchangers at the plasma membrane in order acidify the extracellular matrix and maintain the optimal pH for sustaining cancer growth. Among the families of proton exchangers implicated in carcinogenesis, carbonic anhydrases (CAs), monocarboxylate transporters (MCTs), Na+/H+ exchangers (NHEs), sodium bicarbonate cotransporters (NBCs), and vacuolar ATPases (V-ATPases) are highlighted. Considerable research has been carried out into the utility of the understanding of these machineries in the diagnosis and prognosis of several solid tumors. In addition, as therapeutic targets, the interference of their functions has contributed to the discovery or optimization of cancer therapies. According to recent reports, the study of these mechanisms seems promising in the particular case of oral squamous cell carcinoma (OSCC). In the present review, the latest advances in these fields are summarized, in particular, the usefulness of proton exchangers as potential prognostic biomarkers and therapeutic targets in OSCC.
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Affiliation(s)
- Alejandro I Lorenzo-Pouso
- Oral Medicine, Oral Surgery and Implantology Unit, Faculty of Medicine and Odontology, University of Santiago de Compostela, GI-1319 Research Group, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela, 15782, Spain.
| | - Mario Pérez-Sayáns
- Oral Medicine, Oral Surgery and Implantology Unit, Faculty of Medicine and Odontology, University of Santiago de Compostela, GI-1319 Research Group, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela, 15782, Spain.
| | - Samuel Rodríguez-Zorrilla
- Oral Medicine, Oral Surgery and Implantology Unit, Faculty of Medicine and Odontology, University of Santiago de Compostela, GI-1319 Research Group, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela, 15782, Spain
| | - Cintia Chamorro-Petronacci
- Oral Medicine, Oral Surgery and Implantology Unit, Faculty of Medicine and Odontology, University of Santiago de Compostela, GI-1319 Research Group, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela, 15782, Spain
| | - Abel García-García
- Oral Medicine, Oral Surgery and Implantology Unit, Faculty of Medicine and Odontology, University of Santiago de Compostela, GI-1319 Research Group, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela, 15782, Spain
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23
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Gregório SF, Ruiz-Jarabo I, Carvalho EM, Fuentes J. Increased intestinal carbonate precipitate abundance in the sea bream (Sparus aurata L.) in response to ocean acidification. PLoS One 2019; 14:e0218473. [PMID: 31226164 PMCID: PMC6588277 DOI: 10.1371/journal.pone.0218473] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/03/2019] [Indexed: 12/20/2022] Open
Abstract
Marine fish contribute to the carbon cycle by producing mineralized intestinal precipitates generated as by-products of their osmoregulation. Here we aimed at characterizing the control of epithelial bicarbonate secretion and intestinal precipitate presence in the gilthead sea bream in response to predicted near future increases of environmental CO2. Our results demonstrate that hypercapnia (950 and 1800 μatm CO2) elicits higher intestine epithelial HCO3- secretion ex vivo and a subsequent parallel increase of intestinal precipitate presence in vivo when compared to present values (440 μatm CO2). Intestinal gene expression analysis in response to environmental hypercapnia revealed the up-regulation of transporters involved in the intestinal bicarbonate secretion cascade such as the basolateral sodium bicarbonate co-transporter slc4a4, and the apical anion transporters slc26a3 and slc26a6 of sea bream. In addition, other genes involved in intestinal ion uptake linked to water absorption such as the apical nkcc2 and aquaporin 1b expression, indicating that hypercapnia influences different levels of intestinal physiology. Taken together the current results are consistent with an intestinal physiological response leading to higher bicarbonate secretion in the intestine of the sea bream paralleled by increased luminal carbonate precipitate abundance and the main related transporters in response to ocean acidification.
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Affiliation(s)
- Sílvia F. Gregório
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Ignacio Ruiz-Jarabo
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Edison M. Carvalho
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Juan Fuentes
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
- * E-mail:
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24
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Xu J, Barone S, Zahedi K, Brooks M, Soleimani M. Slc4a8 in the Kidney: Expression, Subcellular Localization and Role in Salt Reabsorption. Cell Physiol Biochem 2018; 50:1361-1375. [PMID: 30355950 DOI: 10.1159/000494596] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 10/17/2018] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS The sodium-dependent bicarbonate transporter Slc4a8 (a.k.a NDCBE) mediates the co-transport of sodium and bicarbonate in exchange for chloride. It is abundantly detected in the brain, with low expression levels in the kidney. The cell distribution and subcellular localization of Slc4a8 in the kidney and its role in acid/base and electrolyte homeostasis has been the subject of conflicting reports. There are no conclusive localization or functional studies to pinpoint the location and demonstrate the function of Slc4a8 in the kidney. METHODS Molecular techniques, including RT-PCR and in situ hybridization, were performed on kidney sections and tagged epitopes were used to examine the membrane targeting of Slc4a8 in polarized kidney cells. Crispr/Cas9 was used to generate and examine Slc4a8 KO mice. RESULTS Zonal distribution and in situ hybridization studies showed very little expression for Slc4a8 (NDCBE) in the cortex or in cortical collecting ducts (CCD). Slc4a8 was predominantly detected in the outer and inner medullary collecting ducts (OMCD and IMCD), and was targeted to the basolateral membrane of osmotically tolerant MDCK cells. Slc4a8 KO mice did not show any abnormal salt or bicarbonate wasting under baseline conditions or in response to bicarbonate loading, salt restriction or furosemide-induced diuresis. CONCLUSION Slc4a8 (NDCBE) is absent in the CCD and is predominantly localized on the basolateral membrane of medullary collecting duct cells. Further, Slc4a8 deletion does not cause significant acid base or electrolyte abnormalities in pathophysiologic states. Additional studies are needed to examine the role of Slc4a8 (NDCBE) in intracellular pH and volume regulation in medullary collecting duct cells.
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25
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Abstract
Astrocytes are a glial cell type, which is indispensable for brain energy metabolism. Within cells, the NADH/NAD+ redox state is a crucial node in metabolism connecting catabolic pathways to oxidative phosphorylation and ATP production in mitochondria. To characterize the dynamics of the intracellular NADH/NAD+ redox state in cortical astrocytes Peredox, a genetically encoded sensor for the NADH/NAD+ redox state, was expressed in cultured cortical astrocytes as well as in cortical astrocytes in acutely isolated brain slices. Calibration of the sensor in cultured astrocytes revealed a mean basal cytosolic NADH/NAD+ redox ratio of about 0.01; however, with a broad distribution and heterogeneity in the cell population, which was mirrored by a heterogeneous basal cellular concentration of lactate. Inhibition of glucose uptake decreased the NADH/NAD+ redox state while inhibition of lactate dehydrogenase or of lactate release resulted in an increase in the NADH/NAD+ redox ratio. Furthermore, the NADH/NAD+ redox state was regulated by the extracellular concentration of K+ , and application of the neurotransmitters ATP or glutamate increased the NADH/NAD+ redox state dependent on purinergic receptors and glutamate uptake, respectively. This regulation by K+ , ATP, and glutamate involved NBCe1 mediated sodium-bicarbonate transport. These results demonstrate that the NADH/NAD+ redox state in astrocytes is a metabolic node regulated by neuronal signals reflecting physiological activity, most likely contributing to adjust astrocytic metabolism to energy demand of the brain.
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Affiliation(s)
- Susanne Köhler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Ulrike Winkler
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Marit Sicker
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
| | - Johannes Hirrlinger
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, University of Leipzig, Leipzig, Germany
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
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Fang L, Lee HW, Chen C, Harris AN, Romero MF, Verlander JW, Weiner ID. Expression of the B splice variant of NBCe1 (SLC4A4) in the mouse kidney. Am J Physiol Renal Physiol 2018; 315:F417-F428. [PMID: 29631353 PMCID: PMC6172571 DOI: 10.1152/ajprenal.00515.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 03/07/2018] [Accepted: 03/29/2018] [Indexed: 01/10/2023] Open
Abstract
Sodium-coupled bicarbonate transporters are critical for renal electrolyte transport. The electrogenic, sodium-coupled bicarbonate cotransporter, isoform 1 (NBCe1), encoded by the SLC4A4 geneencoded by the SLC4A4 gene has five multiple splice variants; the A splice variant, NBCe1-A, is the primary basolateral bicarbonate transporter in the proximal convoluted tubule. This study's purpose was to determine if there is expression of additional NBCe1 splice variants in the mouse kidney, their cellular distribution, and their regulation by metabolic acidosis. In wild-type mice, an antibody reactive only to NBCe1-A showed basolateral immunolabel only in cortical proximal tubule (PT) segments, whereas an antibody reactive to all NBCe1 splice variants (pan-NBCe1) showed basolateral immunolabel in PT segments in both the cortex and outer medulla. In mice with NBCe1-A deletion, the pan-NBCe1 antibody showed basolateral PT immunolabel in both the renal cortex and outer stripe of the outer medulla, and immunoblot analysis showed expression of a ~121-kDa protein. RT-PCR of mRNA from NBCe1-A knockout mice directed at splice variant-specific regions showed expression of only NBCe1-B mRNA. In wild-type kidney, RT-PCR confirmed expression of mRNA for the NBCe1-B splice variant and absence of mRNA for the C, D, and E splice variants. Finally, exogenous acid loading increased expression in the proximal straight tubule in the outer stripe of the outer medulla. These studies demonstrate that the NBCe1-B splice variant is present in the PT, and its expression increases in response to exogenous acid loading, suggesting it participates in the PT contribution to acid-base homeostasis.
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Affiliation(s)
- Lijuan Fang
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine , Gainesville, Florida
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine , Gainesville, Florida
| | - Chao Chen
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine , Gainesville, Florida
| | - Autumn N Harris
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine , Gainesville, Florida
| | - Michael F Romero
- Department of Physiology and Biomedical Engineering, Mayo Clinic , Rochester, Minnesota
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine , Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine , Gainesville, Florida
- Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida
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Mukaibo T, Munemasa T, George AT, Tran DT, Gao X, Herche JL, Masaki C, Shull GE, Soleimani M, Melvin JE. The apical anion exchanger Slc26a6 promotes oxalate secretion by murine submandibular gland acinar cells. J Biol Chem 2018; 293:6259-6268. [PMID: 29530983 PMCID: PMC5925796 DOI: 10.1074/jbc.ra118.002378] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/08/2018] [Indexed: 12/15/2022] Open
Abstract
The solute carrier family 26 (SLC26) gene family encodes at least 10 different anion exchangers. SLC26 member 6 (SLC26A6 or CFEX/PAT-1) and the cystic fibrosis transmembrane conductance regulator (CFTR) co-localize to the apical membrane of pancreatic duct cells, where they act in concert to drive HCO3- and fluid secretion. In contrast, in the small intestine, SLC26A6 serves as the major pathway for oxalate secretion. However, little is known about the function of Slc26a6 in murine salivary glands. Here, RNA sequencing-based transcriptional profiling and Western blots revealed that Slc26a6 is highly expressed in mouse submandibular and sublingual salivary glands. Slc26a6 localized to the apical membrane of salivary gland acinar cells with no detectable immunostaining in the ducts. CHO-K1 cells transfected with mouse Slc26a6 exchanged Cl- for oxalate and HCO3-, whereas two other anion exchangers known to be expressed in salivary gland acinar cells, Slc4a4 and Slc4a9, mediated little, if any, Cl-/oxalate exchange. Of note, both Cl-/oxalate exchange and Cl-/HCO3- exchange were significantly reduced in acinar cells isolated from the submandibular glands of Slc26a6-/- mice. Oxalate secretion in submandibular saliva also decreased significantly in Slc26a6-/- mice, but HCO3- secretion was unaffected. Taken together, our findings indicate that Slc26a6 is located at the apical membrane of salivary gland acinar cells, where it mediates Cl-/oxalate exchange and plays a critical role in the secretion of oxalate into saliva.
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Affiliation(s)
- Taro Mukaibo
- From the Secretory Mechanisms and Dysfunctions Section and
- the Department of Oral Reconstruction and Rehabilitation, Kyushu Dental University, Kitakyushu, Fukuoka 803-8580, Japan
| | - Takashi Munemasa
- From the Secretory Mechanisms and Dysfunctions Section and
- the Department of Oral Reconstruction and Rehabilitation, Kyushu Dental University, Kitakyushu, Fukuoka 803-8580, Japan
| | - Alvin T George
- From the Secretory Mechanisms and Dysfunctions Section and
| | - Duy T Tran
- Biological Chemistry Section, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
| | - Xin Gao
- From the Secretory Mechanisms and Dysfunctions Section and
- the Joint Institute for Food Safety and Applied Nutrition, University of Maryland, College Park, Maryland 20742, and
| | - Jesse L Herche
- From the Secretory Mechanisms and Dysfunctions Section and
| | - Chihiro Masaki
- the Department of Oral Reconstruction and Rehabilitation, Kyushu Dental University, Kitakyushu, Fukuoka 803-8580, Japan
| | - Gary E Shull
- Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | | | - James E Melvin
- From the Secretory Mechanisms and Dysfunctions Section and
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Gildea JJ, Xu P, Kemp BA, Carlson JM, Tran HT, Bigler Wang D, Langouët-Astrié CJ, McGrath HE, Carey RM, Jose PA, Felder RA. Sodium bicarbonate cotransporter NBCe2 gene variants increase sodium and bicarbonate transport in human renal proximal tubule cells. PLoS One 2018; 13:e0189464. [PMID: 29642240 PMCID: PMC5895442 DOI: 10.1371/journal.pone.0189464] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 11/28/2017] [Indexed: 01/11/2023] Open
Abstract
RATIONALE Salt sensitivity of blood pressure affects >30% of the hypertensive and >15% of the normotensive population. Variants of the electrogenic sodium bicarbonate cotransporter NBCe2 gene, SLC4A5, are associated with increased blood pressure in several ethnic groups. SLC4A5 variants are also highly associated with salt sensitivity, independent of hypertension. However, little is known about how NBCe2 contributes to salt sensitivity, although NBCe2 regulates renal tubular sodium bicarbonate transport. We hypothesized that SLC4A5 rs10177833 and rs7571842 increase NBCe2 expression and human renal proximal tubule cell (hRPTC) sodium transport and may be a cause of salt sensitivity of blood pressure. OBJECTIVE To characterize the hRPTC ion transport of wild-type (WT) and homozygous variants (HV) of SLC4A5. METHODS AND RESULTS The expressions of NBCe2 mRNA and protein were not different between hRPTCs carrying WT or HV SLC4A5 before or after dopaminergic or angiotensin (II and III) stimulation. However, luminal to basolateral sodium transport, NHE3 protein, and Cl-/HCO3- exchanger activity in hRPTCs were higher in HV than WT SLC4A5. Increasing intracellular sodium enhanced the apical location of NBCe2 in HV hRPTCs (4.24±0.35% to 11.06±1.72% (P<0.05, N = 3, 2-way ANOVA, Holm-Sidak test)) as determined by Total Internal Reflection Fluorescence Microscopy (TIRFM). In hRPTCs isolated from kidney tissue, increasing intracellular sodium enhanced bicarbonate-dependent pH recovery rate and increased NBCe2 mRNA and protein expressions to a greater extent in HV than WT SLC4A5 (+38.00±6.23% vs HV normal salt (P<0.01, N = 4, 2-way ANOVA, Holm-Sidak test)). In hRPTCs isolated from freshly voided urine, bicarbonate-dependent pH recovery was also faster in those from salt-sensitive and carriers of HV SLC4A5 than from salt-resistant and carriers of WT SLC4A5. The faster NBCe2-specific bicarbonate-dependent pH recovery rate in HV SCL4A5 was normalized by SLC4A5- but not SLC4A4-shRNA. The binding of purified hepatocyte nuclear factor type 4A (HNF4A) to DNA was increased in hRPTCs carrying HV SLC4A5 rs7571842 but not rs10177833. The faster NBCe2-specific bicarbonate-dependent pH recovery rate in HV SCL4A5 was abolished by HNF4A antagonists. CONCLUSION NBCe2 activity is stimulated by an increase in intracellular sodium and is hyper-responsive in hRPTCs carrying HV SLC4A5 rs7571842 through an aberrant HNF4A-mediated mechanism.
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Affiliation(s)
- John J. Gildea
- The University of Virginia Department of Pathology, Charlottesville, VA, United States of America
| | - Peng Xu
- The University of Virginia Department of Pathology, Charlottesville, VA, United States of America
| | - Brandon A. Kemp
- The University of Virginia Department of Medicine, Charlottesville, VA, United States of America
| | - Julia M. Carlson
- The University of Virginia Department of Pathology, Charlottesville, VA, United States of America
| | - Hanh T. Tran
- The University of Virginia Department of Pathology, Charlottesville, VA, United States of America
| | - Dora Bigler Wang
- The University of Virginia Department of Pathology, Charlottesville, VA, United States of America
| | | | - Helen E. McGrath
- The University of Virginia Department of Pathology, Charlottesville, VA, United States of America
| | - Robert M. Carey
- The University of Virginia Department of Medicine, Charlottesville, VA, United States of America
| | - Pedro A. Jose
- The George Washington University School of Medicine & Health Sciences, Department of Medicine, Division of Renal Disease and Hypertension and Department of Pharmacology and Physiology, Washington, DC, United States of America
| | - Robin A. Felder
- The University of Virginia Department of Pathology, Charlottesville, VA, United States of America
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Chen GS, Lee SP, Huang SF, Chao SC, Chang CY, Wu GJ, Li CH, Loh SH. Functional and molecular characterization of transmembrane intracellular pH regulators in human dental pulp stem cells. Arch Oral Biol 2018. [PMID: 29524788 DOI: 10.1016/j.archoralbio.2018.02.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE Homeostasis of intracellular pH (pHi) plays vital roles in many cell functions, such as proliferation, apoptosis, differentiation and metastasis. Thus far, Na+-H+ exchanger (NHE), Na+-HCO3- co-transporter (NBC), Cl-/HCO3- exchanger (AE) and Cl-/OH- exchanger (CHE) have been identified to co-regulate pHi homeostasis. However, functional and biological pHi-regulators in human dental pulp stem cells (hDPSCs) have yet to be identified. DESIGN Microspectrofluorimetry technique with pH-sensitive fluorescent dye, BCECF, was used to detect pHi changes. NH4Cl and Na+-acetate pre-pulse were used to induce intracellular acidosis and alkalosis, respectively. Isoforms of pHi-regulators were detected by Western blot technique. RESULTS The resting pHi was no significant difference between that in HEPES-buffered (nominal HCO3--free) solution or CO2/HCO3-buffered system (7.42 and 7.46, respectively). The pHi recovery following the induced-intracellular acidosis was blocked completely by removing [Na+]o, while only slowed (-63%) by adding HOE694 (a NHE1 specific inhibitor) in HEPES-buffered solution. The pHi recovery was inhibited entirely by removing [Na+]o, while adding HOE 694 pulse DIDS (an anion-transporter inhibitor) only slowed (-55%) the acid extrusion. Both in HEPES-buffered and CO2/HCO3-buffered system solution, the pHi recovery after induced-intracellular alkalosis was entirely blocked by removing [Cl-]o. Western blot analysis showed the isoforms of pHi regulators, including NHE1/2, NBCe1/n1, AE1/2/3/4 and CHE in the hDPSCs. CONCLUSIONS We demonstrate for the first time that resting pHi is significantly higher than 7.2 and meditates functionally by two Na+-dependent acid extruders (NHE and NBC), two Cl--dependent acid loaders (CHE and AE) and one Na+-independent acid extruder(s) in hDPSCs. These findings provide novel insight for basic and clinical treatment of dentistry.
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Affiliation(s)
- Gunng-Shinng Chen
- Division of Orthodontic, Dentofacial Orthopedic & Pediatric Dentistry, Department of Dentistry, School of Dentistry, Tri-Service General Hospital and National Defense Medical Center, Taipei 114, Taiwan
| | - Shiao-Pieng Lee
- Division of Oral and Maxillofacial Surgery, Department of Dentistry, School of Dentistry, Tri-Service General Hospital and National Defense Medical Center, Taipei 114, Taiwan
| | - Shu-Fu Huang
- Department of Clinical Pharmacy, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan
| | - Shih-Chi Chao
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan; Department of Pharmacology, National Defense Medical Center, Taipei 114, Taiwan
| | - Chung-Yi Chang
- Heart Center and Department of General Surgery, Cheng Hsin General Hospital, Taipei 112, Taiwan
| | - Gwo-Jang Wu
- Department of Obstetrics and Gynecology, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan
| | - Chung-Hsing Li
- Division of Orthodontic, Dentofacial Orthopedic & Pediatric Dentistry, Department of Dentistry, School of Dentistry, Tri-Service General Hospital and National Defense Medical Center, Taipei 114, Taiwan
| | - Shih-Hurng Loh
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan; Department of Pharmacology, National Defense Medical Center, Taipei 114, Taiwan.
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Li Q, Ding Y, Krafft P, Wan W, Yan F, Wu G, Zhang Y, Zhan Q, Zhang JH. Targeting Germinal Matrix Hemorrhage-Induced Overexpression of Sodium-Coupled Bicarbonate Exchanger Reduces Posthemorrhagic Hydrocephalus Formation in Neonatal Rats. J Am Heart Assoc 2018; 7:e007192. [PMID: 29386206 PMCID: PMC5850237 DOI: 10.1161/jaha.117.007192] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/21/2017] [Indexed: 02/01/2023]
Abstract
BACKGROUND Germinal matrix hemorrhage (GMH) is a leading cause of mortality and lifelong morbidity in preterm infants. Posthemorrhagic hydrocephalus (PHH) is a common complication of GMH. A sodium-coupled bicarbonate exchanger (NCBE) encoded by solute carrier family 4 member 10 gene is expressed on the choroid plexus basolateral membrane and may play a role in cerebrospinal fluid production and the development of PHH. Following GMH, iron degraded from hemoglobin has been linked to PHH. Choroid plexus epithelial cells also contain iron-responsive element-binding proteins (IRPs), IRP1, and IRP2 that bind to mRNA iron-responsive elements. The present study aims to resolve the following issues: (1) whether the expression of NCBE is regulated by IRPs; (2) whether NCBE regulates the formation of GMH-induced hydrocephalus; and (3) whether inhibition of NCBE reduces PHH development. METHODS AND RESULTS GMH model was established in P7 rat pups by injecting bacterial collagenase into the right ganglionic eminence. Another group received iron trichloride injections instead of collagenase. Deferoxamine was administered intraperitoneally for 3 consecutive days after GMH/iron trichloride. Solute carrier family 4 member 10 small interfering RNA or scrambled small interfering RNA was administered by intracerebroventricular injection 24 hours before GMH and followed with an injection every 7 days over 21 days. NCBE expression increased while IRP2 expression decreased after GMH/iron trichloride. Deferoxamine ameliorated both the GMH-induced and iron trichloride-induced decrease of IRP2 and decreased NCBE expressions. Deferoxamine and solute carrier family 4 member 10 small interfering RNA improved cognitive and motor functions at 21 to 28 days post GMH and reduced cerebrospinal fluid production as well as the degree of hydrocephalus at 28 days after GMH. CONCLUSIONS Targeting iron-induced overexpression of NCBE may be a translatable therapeutic strategy for the treatment of PHH following GMH.
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Affiliation(s)
- Qian Li
- Department of Neurology, The Fifth People's Hospital of Chongqing, Chongqing, China
| | - Yan Ding
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA
| | - Paul Krafft
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA
| | - Weifeng Wan
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA
| | - Feng Yan
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA
| | - Guangyong Wu
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA
| | - Yixin Zhang
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA
| | - Qunling Zhan
- Department of Neurology, The Fifth People's Hospital of Chongqing, Chongqing, China
| | - John H Zhang
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA
- Department of Anesthesiology, Loma Linda University School of Medicine, Loma Linda, CA
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Abstract
Amelogenesis (tooth enamel formation) is a biomineralization process consisting primarily of two stages (secretory stage and maturation stage) with unique features. During the secretory stage, the inner epithelium of the enamel organ (i.e., the ameloblast cells) synthesizes and secretes enamel matrix proteins (EMPs) into the enamel space. The protein-rich enamel matrix forms a highly organized architecture in a pH-neutral microenvironment. As amelogenesis transitions to maturation stage, EMPs are degraded and internalized by ameloblasts through endosomal-lysosomal pathways. Enamel crystallite formation is initiated early in the secretory stage, however, during maturation stage the more rapid deposition of calcium and phosphate into the enamel space results in a rapid expansion of crystallite length and mineral volume. During maturation-stage amelogenesis, the pH value of enamel varies considerably from slightly above neutral to acidic. Extracellular acid-base balance during enamel maturation is tightly controlled by ameloblast-mediated regulatory networks, which include significant synthesis and movement of bicarbonate ions from both the enamel papillary layer cells and ameloblasts. In this review we summarize the carbonic anhydrases and the carbonate transporters/exchangers involved in pH regulation in maturation-stage amelogenesis. Proteins that have been shown to be instrumental in this process include CA2, CA6, CFTR, AE2, NBCe1, SLC26A1/SAT1, SLC26A3/DRA, SLC26A4/PDS, SLC26A6/PAT1, and SLC26A7/SUT2. In addition, we discuss the association of miRNA regulation with bicarbonate transport in tooth enamel formation.
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Affiliation(s)
- Kaifeng Yin
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar Street, CSA103, Los Angeles, CA, 90033, USA
- Department of Orthodontics, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA
| | - Michael L Paine
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar Street, CSA103, Los Angeles, CA, 90033, USA.
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Khakipoor S, Ophoven C, Schrödl‐Häußel M, Feuerstein M, Heimrich B, Deitmer JW, Roussa E. TGF-β signaling directly regulates transcription and functional expression of the electrogenic sodium bicarbonate cotransporter 1, NBCe1 (SLC4A4), via Smad4 in mouse astrocytes. Glia 2017; 65:1361-1375. [PMID: 28568893 PMCID: PMC5518200 DOI: 10.1002/glia.23168] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 04/27/2017] [Accepted: 05/04/2017] [Indexed: 02/06/2023]
Abstract
The electrogenic sodium bicarbonate cotransporter NBCe1 (SLC4A4) expressed in astrocytes regulates intracellular and extracellular pH. Here, we introduce transforming growth factor beta (TGF-β) as a novel regulator of NBCe1 transcription and functional expression. Using hippocampal slices and primary hippocampal and cortical astrocyte cultures, we investigated regulation of NBCe1 and elucidated the underlying signaling pathways by RT-PCR, immunoblotting, immunofluorescence, intracellular H(+ ) recording using the H(+ ) -sensitive dye 2',7'-bis-(carboxyethyl)-5-(and-6)-carboxyfluorescein, mink lung epithelial cell (MLEC) assay, and chromatin immunoprecipitation. Activation of TGF-β signaling significantly upregulated transcript, protein, and surface expression of NBCe1. These effects were TGF-β receptor-mediated and suppressed following inhibition of JNK and Smad signaling. Moreover, 4-aminopyridine (4AP)-dependent NBCe1 regulation requires TGF-β. TGF-β increased the rate and amplitude of intracellular H+ changes upon challenging NBCe1 in wild-type astrocytes but not in cortical astrocytes from Slc4a4-deficient mice. A Smad4 binding sequence was identified in the NBCe1 promoter and Smad4 binding increased after activation of TGF-β signaling. The data show for the first time that NBCe1 is a direct target of TGF-β/Smad4 signaling. Through activation of the canonical pathway TGF-β acts directly on NBCe1 by binding of Smad4 to the NBCe1 promoter and regulating its transcription, followed by increased protein expression and transport activity.
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Affiliation(s)
- Shokoufeh Khakipoor
- Department of Molecular EmbryologyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
| | - Christian Ophoven
- Department of Molecular EmbryologyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
| | - Magdalena Schrödl‐Häußel
- Department of Molecular EmbryologyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
| | - Melanie Feuerstein
- Department of Molecular EmbryologyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
| | - Bernd Heimrich
- Department of NeuroanatomyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
| | - Joachim W. Deitmer
- Department of General ZoologyFB Biology, University of KaiserslauternP.B. 3049D‐67653KaiserslauternGermany
| | - Eleni Roussa
- Department of Molecular EmbryologyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
- Department of NeuroanatomyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
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Cai YM, Chen T, Ren CH, Huang W, Jiang X, Gao Y, Huo D, Hu CQ. Molecular characterization of Pacific white shrimp (Litopenaeus vannamei) sodium bicarbonate cotransporter (NBC) and its role in response to pH stress. Fish Shellfish Immunol 2017; 64:226-233. [PMID: 28257848 DOI: 10.1016/j.fsi.2017.02.047] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 02/24/2017] [Accepted: 02/27/2017] [Indexed: 06/06/2023]
Abstract
The sodium bicarbonate cotransporter (NBC) is an integral membrane ion transporter that can transport HCO3- (or a related species, such as CO32-) across the plasma membrane. Previous researches revealed that NBC might play an important role in the regulation of intracellular pH in vertebrates. In the present study, an NBC cDNA was identified from Pacific white shrimp (Litopenaeus vannamei) and designated as Lv-NBC. The full-length Lv-NBC cDNA is 4479 bp in size, containing a 5'-untranslated region (UTR) of 59 bp, a 3'-UTR of 835 bp and an open reading frame (ORF) of 3585 bp that encodes a protein of 1194 amino acids with a deduced molecular weight of 134.34 kDa. The Lv-NBC protein contains two functional domains (Band_3_cyto and HCO3_cotransp) and twelve transmembrane (TM) domains. Expression of the Lv-NBC mRNA was ubiquitously detected in all selected tissues, with the highest level in the gill. By in situ hybridization (ISH) with Digoxigenin-labeled probe, the Lv-NBC positive cells were shown mainly located in the secondary gill filaments. After low or high pH challenge, the transcript levels of Lv-NBC in the gill were found to be up-regulated. After knockdown of the Lv-NBC level by siRNA, the mortality of shrimp significantly increased under pH stress. Our study, as a whole, may provide evidences for the role of NBC in shrimp responding to pH stress, and give a new insight of the acid/base homeostasis mechanism in crustaceans.
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Affiliation(s)
- Yi-Ming Cai
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Ting Chen
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Guangzhou, China.
| | - Chun-Hua Ren
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Guangzhou, China.
| | - Wen Huang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.
| | - Xiao Jiang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.
| | - Yan Gao
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Da Huo
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Chao-Qun Hu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Guangzhou, China.
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Shahzad H, Giribabu N, Karim K, Kassim NM, Muniandy S, Salleh N. Combinatorial effects of quercetin and sex-steroids on fluid and electrolytes' (Na+, Cl-, HCO3-) secretory mechanisms in the uterus of ovariectomised female Sprague-Dawley rats. PLoS One 2017; 12:e0172765. [PMID: 28253299 PMCID: PMC5333842 DOI: 10.1371/journal.pone.0172765] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 02/09/2017] [Indexed: 12/18/2022] Open
Abstract
Dysregulation of uterine fluid environment could impair successful reproduction and this could be due to the effect of environmental estrogens. Therefore, in this study, effect of quercetin, an environmental estrogen on uterine fluid and electrolytes concentrations were investigated under sex-steroid influence. Ovariectomised adult female Sprague-Dawley rats were given 10, 50 or 100mg/kg/day quercetin subcutaneously with 17-β estradiol (E) for seven days or three days E, then three days E plus progesterone (P) (E+P) treatment. Uterine fluid secretion rate, Na+, Cl- and HCO3- concentrations were determined by in-vivo perfusion. Following sacrifice, uteri were harvested and levels of the proteins of interest were identified by Western blotting and Realtime PCR. Distribution of these proteins in the uterus was observed by immunofluorescence. Levels of uterine cAMP were measured by enzyme-linked immunoassay (EIA). Administration of quercetin at increasing doses increased uterine fluid secretion rate, Na+, Cl- and HCO3- concentrations, but to the levels lesser than that of E. In concordant, levels of CFTR, SLC4A4, ENaC (α, β and γ), Na+/K+-ATPase, GPα/β, AC and cAMP in the uterus increased following increased in the doses of quercetin. Co-administration of quercetin with E caused uterine fluid secretion rate, Na+, Cl- and HCO3- concentrations to decrease. In concordant, uterine CFTR, SLC26A6, SLC4A4, ENaC (α, β and γ), Na+/K+-ATPase, GPα/β, AC and cAMP decreased. Greatest effects were observed following co-administration of 10mg/kg/day quercetin with E. Co-administration of quercetin with E+P caused uterine fluid Na+ and HCO3- concentrations to increase but no changes in fluid secretion rate and Cl- concentration were observed. Co-administration of high dose quercetin (100 mg/kg/day) with E+P caused uterine CFTR, SLC26A6, AC, GPα/β and ENaC (α, β and γ) to increase. Quercetin-induced changes in the uterine fluid secretion rate and electrolytes concentrations could potentially affect the uterine reproductive functions under female sex-steroid influence.
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Affiliation(s)
- Huma Shahzad
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
| | - Nelli Giribabu
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
| | - Kamarulzaman Karim
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
| | - Normadiah M. Kassim
- Department of Anatomy, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
| | - Sekaran Muniandy
- Department of Biochemistry, Faculty of Medicine and Biomedical Sciences, MAHSA University, Jalan Elmu, Off Jalan University, Kuala Lumpur, Malaysia
| | - Naguib Salleh
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur, Malaysia
- * E-mail:
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Chao PC, Butt AG. cAMP-dependent secretagogues stimulate the NaHCO 3 cotransporter in the villous epithelium of the brushtail possum, Trichosurus vulpecula. J Comp Physiol B 2017; 187:1019-1028. [PMID: 28247055 DOI: 10.1007/s00360-017-1063-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 01/30/2017] [Accepted: 02/05/2017] [Indexed: 12/22/2022]
Abstract
In the ileum of the brushtail possum, Trichosurus vulpecula, fluid secretion appears to be driven by electrogenic HCO3- secretion. Consistent with this, the cystic fibrosis transmembrane conductance regulator is expressed in the apical membrane of the ileal epithelial cells and the pancreatic or secretory variant of the NaHCO3 cotransporter in the basolateral membrane. This suggests that in the possum ileum, electrogenic HCO3- secretion is driven by basolateral NaHCO3 cotransporter (NBC) activity. To determine if the NBC contributes to HCO3- secretion in the possum ileum, intracellular pH (pHi) measurements in isolated villi were used to demonstrate NBC activity in the ileal epithelial cells and investigate the effect of cAMP-dependent secretagogues. In CO2/HCO3--free solutions, recovery of the epithelial cells from an acid load was Na+-dependent and ≈80% inhibited by ethyl-isopropyl-amiloride (EIPA, 10 µmol L-1), indicative of the presence of an Na+/H+ exchanger, most likely NHE1. However, in the presence of CO2/HCO3-, EIPA only inhibited ≈ 50% of the recovery, the remainder was inhibited by 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS, 500 µmol L-1), indicative of NBC activity. Under steady-state conditions, NHE1 inhibition by EIPA had little effect on pHi in the presence or absence of secretagogues, but NBC inhibition with DIDS resulted in a rapid acidification of the cells, which was increased fivefold by secretagogues. These data demonstrate the functional activity of an NaHCO3 cotransporter in the ileal epithelial cells. Furthermore, the stimulation of NBC activity by secretagogues is consistent with the involvement of an NaHCO3 cotransporter in electrogenic HCO3- secretion.
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Affiliation(s)
- Pin-Chun Chao
- Department of Physiology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - A Grant Butt
- Department of Physiology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin, 9054, New Zealand.
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Wang L, Li H, Yang B, Guo L, Han X, Li L, Li M, Huang J, Gu D. The Hypertension Risk Variant Rs820430 Functions as an Enhancer of SLC4A7. Am J Hypertens 2017; 30:202-208. [PMID: 27784683 DOI: 10.1093/ajh/hpw127] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 08/31/2016] [Accepted: 09/16/2016] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND The large-scale meta-analysis of genome-wide association study (GWAS) recently identified a genomic locus where the genetic variant at rs820430 was strongly associated with hypertension in Chinese Han population, with its T allele conferred increased risks. However, the biological and disease-relevant mechanisms for this association remain elusive. METHODS A group of 275 participants from rural district of Shandong Province were enrolled, rs820430 was genotyped using genomic DNA with the fluorogenic 5'-nuclease TaqMan allelic discrimination assay system (Applied Biosystems, CA). In vitro experiments were performed in this study, such as luciferase reporter assays, gel mobility shift assays (electrophoretic mobility shift assay), and chromatin immunoprecipitation. RESULTS We found the risk T allele of rs820430 was associated with higher SLC4A7 mRNA level in cohort population. Furthermore, we characterized a cis-regulatory mechanism that the T allele of rs820430 distinctively increased c-Fos transcription factor binding, by which leading to increased SLC4A7 expression. CONCLUSIONS The present study indicated that the disease-associated T allele of a new hypertension risk variant rs820430 linked increased hypertension risk through higher SLC4A7 expression, and rs820430 functioned as an enhancer of SLC4A7 transcription by allele distinctively increased c-Fos transcription factor binding.
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Affiliation(s)
- Laiyuan Wang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Hongfan Li
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Bin Yang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Liwei Guo
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Xikun Han
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Lin Li
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Mengting Li
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Jianfeng Huang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Dongfeng Gu
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
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Cao LH, Xia CC, Shi ZC, Wang N, Gu ZH, Yu LZ, Wan Q, De W. Na +/HCO 3- cotransporter is expressed on β and α cells during rat pancreatic development. World J Gastroenterol 2016; 22:9525-9533. [PMID: 27920473 PMCID: PMC5116596 DOI: 10.3748/wjg.v22.i43.9525] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 09/07/2016] [Accepted: 10/10/2016] [Indexed: 02/06/2023] Open
Abstract
AIM To determine the expression and localization of the electrogenic Na+/HCO3- cotransporter (NBC1) in rat pancreas during development.
METHODS The rat pancreas from postnatal and embryos removed from the uterus of pregnant rats that had been sacrificed by CO2 asphyxiation were used. Rat pancreas from embryonic day (E) 15.5 and E18.5 rat embryos was isolated under a stereomicroscope. Rat pancreas from postnatal (P) days 0, 7, 14, 21 and adult was directly isolated by the unaided eye. The RT-PCR analysis of the NBC1 specific region on rat pancreas tissues from different developmental stages. The two antibodies which target the NBC1 common COOH-terminal region and NH2-terminal region detected a clear band of about 145 kDa in the Western blot analysis. The localization of NBC1 was examined by immuno-fluorescence detection.
RESULTS The results revealed the first peak of NBC1 expression at E18.5 and the second peak at P14. Meanwhile, the low NBC1 expression occurred at P7 and adult stages. Our results demonstrated, for the first time, the presence of NBC1 in the plasma membrane of β and α cells, as well as in the basolateral membrane of acinar cells of the rat pancreas at different stages of development.
CONCLUSION The data strongly suggests that NBC1 is diversely expressed in the pancreas at different developmental stages, where it may exert its functions in pancreatic development especially islet cell growth through HCO3- transport and pH regulation.
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Theparambil SM, Weber T, Schmälzle J, Ruminot I, Deitmer JW. Proton Fall or Bicarbonate Rise: GLYCOLYTIC RATE IN MOUSE ASTROCYTES IS PAVED BY INTRACELLULAR ALKALINIZATION. J Biol Chem 2016; 291:19108-17. [PMID: 27422823 PMCID: PMC5009280 DOI: 10.1074/jbc.m116.730143] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 07/12/2016] [Indexed: 01/08/2023] Open
Abstract
Glycolysis is the primary step for major energy production in the cell. There is strong evidence suggesting that glucose consumption and rate of glycolysis are highly modulated by cytosolic pH/[H(+)], but those can also be stimulated by an increase in the intracellular [HCO3 (-)]. Because proton and bicarbonate shift concomitantly, it remained unclear whether enhanced glucose consumption and glycolytic rate were mediated by the changes in intracellular [H(+)] or [HCO3 (-)]. We have asked whether glucose metabolism is enhanced by either a fall in intracellular [H(+)] or a rise in intracellular [HCO3 (-)], or by both, in mammalian astrocytes. We have recorded intracellular glucose in mouse astrocytes using a FRET-based nanosensor, while imposing different intracellular [H(+)] and [CO2]/[HCO3 (-)]. Glucose consumption and glycolytic rate were augmented by a fall in intracellular [H(+)], irrespective of a concomitant rise or fall in intracellular [HCO3 (-)]. Transport of HCO3 (-) into and out of astrocytes by the electrogenic sodium bicarbonate cotransporter (NBCe1) played a crucial role in causing changes in intracellular pH and [HCO3 (-)], but was not obligatory for the pH-dependent changes in glucose metabolism. Our results clearly show that it is the cytosolic pH that modulates glucose metabolism in cortical astrocytes, and possibly also in other cell types.
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Affiliation(s)
- Shefeeq M Theparambil
- From the Abteilung für Allgemeine Zoologie, FB Biologie, University of Kaiserlautern, P. B. 3049, D-67653 Kaiserslautern, Germany and
| | - Tobias Weber
- From the Abteilung für Allgemeine Zoologie, FB Biologie, University of Kaiserlautern, P. B. 3049, D-67653 Kaiserslautern, Germany and
| | - Jana Schmälzle
- From the Abteilung für Allgemeine Zoologie, FB Biologie, University of Kaiserlautern, P. B. 3049, D-67653 Kaiserslautern, Germany and
| | - Ivàn Ruminot
- From the Abteilung für Allgemeine Zoologie, FB Biologie, University of Kaiserlautern, P. B. 3049, D-67653 Kaiserslautern, Germany and the Centro de Estudios Científicos (CECs), Valdivia 5110466, Chile
| | - Joachim W Deitmer
- From the Abteilung für Allgemeine Zoologie, FB Biologie, University of Kaiserlautern, P. B. 3049, D-67653 Kaiserslautern, Germany and
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Abstract
PURPOSE OF REVIEW The purpose of this review is to provide a succinct description of the recent findings that advance our understanding of the fundamental renal process of ammonia metabolism and transport in conditions relevant to the clinician. RECENT FINDINGS Recent studies advance our understanding of renal ammonia metabolism. Mechanisms through which chronic kidney disease and altered dietary protein intake alter ammonia excretion have been identified. Lithium, although it can acutely cause distal renal tubular acidosis, was shown with long-term use to increase urinary ammonia excretion, and this appeared to be mediated, at least in part, by increased Rhcg expression. Gene deletion studies showed that the ammonia recycling enzyme, glutamine synthetase, has a critical role in normal-stimulated and acidosis-stimulated ammonia metabolism and that the proximal tubule basolateral bicarbonate transporter, NBCe1, is necessary for normal ammonia metabolism. Finally, our understanding of the molecular ammonia species, NH3 versus NH4, transported by Rh glycoproteins continues to be advanced. SUMMARY Fundamental studies have been recently published that advance our understanding of the regulation of ammonia metabolism in clinically important circumstances, and our understanding of the mechanisms and regulation of proximal tubule ammonia generation, and the mechanisms through which Rh glycoproteins contribute to ammonia secretion.
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Affiliation(s)
- I. David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, FL 32610
- Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, FL 32611
| | - Jill W. Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, FL 32610
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McIntyre A, Hulikova A, Ledaki I, Snell C, Singleton D, Steers G, Seden P, Jones D, Bridges E, Wigfield S, Li JL, Russell A, Swietach P, Harris AL. Disrupting Hypoxia-Induced Bicarbonate Transport Acidifies Tumor Cells and Suppresses Tumor Growth. Cancer Res 2016; 76:3744-55. [PMID: 27197160 DOI: 10.1158/0008-5472.can-15-1862] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 04/25/2016] [Indexed: 11/16/2022]
Abstract
Tumor hypoxia is associated clinically with therapeutic resistance and poor patient outcomes. One feature of tumor hypoxia is activated expression of carbonic anhydrase IX (CA9), a regulator of pH and tumor growth. In this study, we investigated the hypothesis that impeding the reuptake of bicarbonate produced extracellularly by CA9 could exacerbate the intracellular acidity produced by hypoxic conditions, perhaps compromising cell growth and viability as a result. In 8 of 10 cancer cell lines, we found that hypoxia induced the expression of at least one bicarbonate transporter. The most robust and frequent inductions were of the sodium-driven bicarbonate transporters SLC4A4 and SLC4A9, which rely upon both HIF1α and HIF2α activity for their expression. In cancer cell spheroids, SLC4A4 or SLC4A9 disruption by either genetic or pharmaceutical approaches acidified intracellular pH and reduced cell growth. Furthermore, treatment of spheroids with S0859, a small-molecule inhibitor of sodium-driven bicarbonate transporters, increased apoptosis in the cell lines tested. Finally, RNAi-mediated attenuation of SLC4A9 increased apoptosis in MDA-MB-231 breast cancer spheroids and dramatically reduced growth of MDA-MB-231 breast tumors or U87 gliomas in murine xenografts. Our findings suggest that disrupting pH homeostasis by blocking bicarbonate import might broadly relieve the common resistance of hypoxic tumors to anticancer therapy. Cancer Res; 76(13); 3744-55. ©2016 AACR.
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Affiliation(s)
- Alan McIntyre
- Molecular Oncology Laboratories, Department of Oncology, University of Oxford, Weatherall Institute of Molecular Medicine, Oxford, United Kingdom. Cancer Biology, Division of Cancer and Stem Cells, University of Nottingham, Nottingham, United Kingdom
| | - Alzbeta Hulikova
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Ioanna Ledaki
- Molecular Oncology Laboratories, Department of Oncology, University of Oxford, Weatherall Institute of Molecular Medicine, Oxford, United Kingdom
| | - Cameron Snell
- Nuffield Department of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Dean Singleton
- Molecular Oncology Laboratories, Department of Oncology, University of Oxford, Weatherall Institute of Molecular Medicine, Oxford, United Kingdom
| | - Graham Steers
- Molecular Oncology Laboratories, Department of Oncology, University of Oxford, Weatherall Institute of Molecular Medicine, Oxford, United Kingdom
| | - Peter Seden
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom. Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Dylan Jones
- Molecular Oncology Laboratories, Department of Oncology, University of Oxford, Weatherall Institute of Molecular Medicine, Oxford, United Kingdom
| | - Esther Bridges
- Molecular Oncology Laboratories, Department of Oncology, University of Oxford, Weatherall Institute of Molecular Medicine, Oxford, United Kingdom
| | - Simon Wigfield
- Molecular Oncology Laboratories, Department of Oncology, University of Oxford, Weatherall Institute of Molecular Medicine, Oxford, United Kingdom
| | - Ji-Liang Li
- Molecular Oncology Laboratories, Department of Oncology, University of Oxford, Weatherall Institute of Molecular Medicine, Oxford, United Kingdom
| | - Angela Russell
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom. Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Pawel Swietach
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Adrian L Harris
- Molecular Oncology Laboratories, Department of Oncology, University of Oxford, Weatherall Institute of Molecular Medicine, Oxford, United Kingdom.
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Handlogten ME, Osis G, Lee HW, Romero MF, Verlander JW, Weiner ID. NBCe1 expression is required for normal renal ammonia metabolism. Am J Physiol Renal Physiol 2015; 309:F658-66. [PMID: 26224717 PMCID: PMC4593816 DOI: 10.1152/ajprenal.00219.2015] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 07/26/2015] [Indexed: 11/22/2022] Open
Abstract
The mechanisms regulating proximal tubule ammonia metabolism are incompletely understood. The present study addressed the role of the proximal tubule basolateral electrogenic Na(+)-coupled bicarbonate cotransporter (NBCe1; Slc4a4) in renal ammonia metabolism. We used mice with heterozygous and homozygous NBCe1 gene deletion and compared these mice with their wild-type littermates. Because homozygous NBCe1 gene deletion causes 100% mortality before day 25, we studied mice at day 8 (±1 day). Both heterozygous and homozygous gene deletion caused a gene dose-related decrease in serum bicarbonate. The ability to lower urinary pH was intact, and even accentuated, with NBCe1 deletion. However, in contrast to the well-known effect of metabolic acidosis to increase urinary ammonia excretion, NBCe1 deletion caused a gene dose-related decrease in ammonia excretion. There was no identifiable change in proximal tubule structure by light microscopy. Examination of proteins involved in renal ammonia metabolism showed decreased expression of phosphate-dependent glutaminase and phosphoenolpyruvate carboxykinase, key enzymes in proximal tubule ammonia generation, and increased expression of glutamine synthetase, which recycles intrarenal ammonia and regenerates glutamine. Expression of key proteins involved in ammonia transport outside of the proximal tubule (rhesus B glycoprotein and rhesus C glycoprotein) was not significantly changed by NBCe1 deletion. We conclude from these findings that NBCe1 expression is necessary for normal proximal tubule ammonia metabolism.
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Affiliation(s)
- Mary E Handlogten
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Gunars Osis
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Michael F Romero
- Department of Physiology and Biomedical Engineering and Nephrology and Hypertension, Mayo Clinic College Of Medicine, Rochester, Minnesota; and
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida; Nephrology and Hypertension Section, Gainesville Veterans Administration Medical Center, Gainesville, Florida
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Mokgokong R, Wang S, Taylor CJ, Barrand MA, Hladky SB. Ion transporters in brain endothelial cells that contribute to formation of brain interstitial fluid. Pflugers Arch 2014; 466:887-901. [PMID: 24022703 PMCID: PMC4006130 DOI: 10.1007/s00424-013-1342-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 08/24/2013] [Accepted: 08/24/2013] [Indexed: 02/07/2023]
Abstract
Ions and water transported across the endothelium lining the blood–brain barrier contribute to the fluid secreted into the brain and are important in maintaining appropriate volume and ionic composition of brain interstitial fluid. Changes in this secretion process may occur after stroke. The present study identifies at transcript and protein level ion transporters involved in the movement of key ions and examines how levels of certain of these alter following oxidative stress. Immunohistochemistry provides evidence for Cl−/HCO3− exchanger, AE2, and Na+, HCO3− cotransporters, NBCe1 and NBCn1, on brain microvessels. mRNA analysis by RT-PCR reveals expression of these transporters in cultured rat brain microvascular endothelial cells (both primary and immortalized GPNT cells) and also Na+/H+ exchangers, NHE1 (primary and immortalized) and NHE2 (primary cells only). Knock-down using siRNA in immortalized GPNT cells identifies AE2 as responsible for much of the Cl−/HCO3− exchange following extracellular chloride removal and NHE1 as the transporter that accounts for most of the Na+/H+ exchange following intracellular acidification. Transcript levels of both AE2 and NHE1 are increased following hypoxia/reoxygenation. Further work is now required to determine the localization of the bicarbonate transporters to luminal or abluminal membranes of the endothelial cells as well as to identify and localize additional transport mechanisms that must exist for K+ and Cl−.
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Affiliation(s)
- Ruth Mokgokong
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD UK
| | - Shanshan Wang
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD UK
| | - Caroline J. Taylor
- O’Brien Institute and Department of Surgery, University of Melbourne, St. Vincent’s Hospital, 42 Fitzroy Street, Fitzroy, Melbourne, VIC 3065 Australia
- Faculty of Health Sciences, Australian Catholic University, Melbourne, VIC 3065 Australia
| | - Margery A. Barrand
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD UK
| | - Stephen B. Hladky
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD UK
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Song X, Yamasaki M, Miyazaki T, Konno K, Uchigashima M, Watanabe M. Neuron type- and input pathway-dependent expression of Slc4a10 in adult mouse brains. Eur J Neurosci 2014; 40:2797-810. [PMID: 24905082 DOI: 10.1111/ejn.12636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 04/25/2014] [Accepted: 04/28/2014] [Indexed: 11/29/2022]
Abstract
Slc4a10 was originally identified as a Na(+) -driven Cl(-) /HCO3 (-) exchanger NCBE that transports extracellular Na(+) and HCO3 (-) in exchange for intracellular Cl(-) , whereas other studies argue against a Cl(-) -dependence for Na(+) -HCO3 (-) transport, and thus named it the electroneutral Na(+) /HCO3 (-) cotransporter NBCn2. Here we investigated Slc4a10 expression in adult mouse brains by in situ hybridization and immunohistochemistry. Slc4a10 mRNA was widely expressed, with higher levels in pyramidal cells in the hippocampus and cerebral cortex, parvalbumin-positive interneurons in the hippocampus, and Purkinje cells (PCs) in the cerebellum. Immunohistochemistry revealed an uneven distribution of Slc4a10 within the somatodendritic compartment of cerebellar neurons. In the cerebellar molecular layer, stellate cells and their innervation targets (i.e. PC dendrites in the superficial molecular layer) showed significantly higher labeling than basket cells and their targets (PC dendrites in the basal molecular layer and PC somata). Moreover, the distal dendritic trees of PCs (i.e. parallel fiber-targeted dendrites) had significantly greater labeling than the proximal dendrites (climbing fiber-targeted dendrites). These observations suggest that Slc4a10 expression is regulated in neuron type- and input pathway-dependent manners. Because such an elaborate regulation is also found for K(+) -Cl(-) cotransporter KCC2, a major neuronal Cl(-) extruder, we compared their expression. Slc4a10 and KCC2 overlapped in most somatodendritic elements. However, relative abundance was largely complementary in the cerebellar cortex, with particular enrichments of Slc4a10 in PC dendrites and KCC2 in molecular layer interneurons, granule cells and PC somata. These properties might reflect functional redundancy and distinction of these transporters, and their differential requirements by individual neurons and respective input domains.
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Affiliation(s)
- Xiaohong Song
- Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, 060-8638, Japan; Japan Science and Technology Agency, CREST, Sanbancho, Chiyoda-ku, Tokyo, Japan
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Peetz J, Barros LF, San Martín A, Becker HM. Functional interaction between bicarbonate transporters and carbonic anhydrase modulates lactate uptake into mouse cardiomyocytes. Pflugers Arch 2014; 467:1469-1480. [PMID: 25118990 DOI: 10.1007/s00424-014-1594-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 07/30/2014] [Accepted: 08/04/2014] [Indexed: 11/26/2022]
Abstract
Blood-derived lactate is a precious energy substrate for the heart muscle. Lactate is transported into cardiomyocytes via monocarboxylate transporters (MCTs) together with H(+), which couples lactate uptake to cellular pH regulation. In this study, we have investigated how the interplay between different acid/base transporters and carbonic anhydrases (CA), which catalyze the reversible hydration of CO2, modulates the uptake of lactate into isolated mouse cardiomyocytes. Lactate transport was estimated both as lactate-induced acidification and as changes in intracellular lactate levels measured with a newly developed Förster resonance energy transfer (FRET) nanosensor. Recordings of intracellular pH showed an increase in the rate of lactate-induced acidification when CA was inhibited by 6-ethoxy-2-benzothiazolesulfonamide (EZA), while direct measurements of lactate flux demonstrated a decrease in MCT transport activity, when CA was inhibited. The data indicate that catalytic activity of extracellular CA increases lactate uptake and counteracts intracellular lactate-induced acidification. We propose a hypothetical model, in which HCO3 (-), formed from cell-derived CO2 at the outer surface of the cardiomyocyte plasma membrane by membrane-anchored, extracellular CA, is transported into the cell via Na(+)/HCO3 (-) cotransport to counteract intracellular acidification, while the remaining H(+) stabilizes extracellular pH at the surface of the plasma membrane during MCT activity to enhance lactate influx into cardiomyocytes.
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Affiliation(s)
- Jan Peetz
- Division of Zoology/Membrane Transport, FB Biologie, TU Kaiserslautern, P.O. Box 3049, 67653, Kaiserslautern, Germany
| | | | | | - Holger M Becker
- Division of Zoology/Membrane Transport, FB Biologie, TU Kaiserslautern, P.O. Box 3049, 67653, Kaiserslautern, Germany.
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Wen X, Kurtz I, Paine ML. Prevention of the disrupted enamel phenotype in Slc4a4-null mice using explant organ culture maintained in a living host kidney capsule. PLoS One 2014; 9:e97318. [PMID: 24828138 PMCID: PMC4020772 DOI: 10.1371/journal.pone.0097318] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 04/18/2014] [Indexed: 01/27/2023] Open
Abstract
Slc4a4-null mice are a model of proximal renal tubular acidosis (pRTA). Slc4a4 encodes the electrogenic sodium base transporter NBCe1 that is involved in transcellular base transport and pH regulation during amelogenesis. Patients with mutations in the SLC4A4 gene and Slc4a4-null mice present with dysplastic enamel, amongst other pathologies. Loss of NBCe1 function leads to local abnormalities in enamel matrix pH regulation. Loss of NBCe1 function also results in systemic acidemic blood pH. Whether local changes in enamel pH and/or a decrease in systemic pH are the cause of the abnormal enamel phenotype is currently unknown. In the present study we addressed this question by explanting fetal wild-type and Slc4a4-null mandibles into healthy host kidney capsules to study enamel formation in the absence of systemic acidemia. Mandibular E11.5 explants from NBCe1−/− mice, maintained in host kidney capsules for 70 days, resulted in teeth with enamel and dentin with morphological and mineralization properties similar to cultured NBCe1+/+ mandibles grown under identical conditions. Ameloblasts express a number of proteins involved in dynamic changes in H+/base transport during amelogenesis. Despite the capacity of ameloblasts to dynamically modulate the local pH of the enamel matrix, at least in the NBCe1−/− mice, the systemic pH also appears to contribute to the enamel phenotype. Extrapolating these data to humans, our findings suggest that in patients with NBCe1 mutations, correction of the systemic metabolic acidosis at a sufficiently early time point may lead to amelioration of enamel abnormalities.
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Affiliation(s)
- Xin Wen
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
| | - Ira Kurtz
- Division of Nephrology and Brain Research Institute, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, California, United States of America
| | - Michael L. Paine
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
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Lee S, Mele M, Vahl P, Christiansen PM, Jensen VED, Boedtkjer E. Na+,HCO3- -cotransport is functionally upregulated during human breast carcinogenesis and required for the inverted pH gradient across the plasma membrane. Pflugers Arch 2014; 467:367-77. [PMID: 24788003 DOI: 10.1007/s00424-014-1524-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 04/14/2014] [Accepted: 04/16/2014] [Indexed: 12/21/2022]
Abstract
Metabolic and biochemical changes during breast carcinogenesis enhance cellular acid production. Extrusion of the acid load from the cancer cells raises intracellular pH, while it decreases extracellular pH creating an inverted pH gradient across the plasma membrane compared to normal cells and promoting cancer cell metabolism, proliferation, migration, and invasion. We investigated the effects of breast carcinogenesis on the mechanisms of cellular pH control using multicellular epithelial organoids freshly isolated from human primary breast carcinomas and matched normal breast tissue. Intracellular pH was measured by fluorescence microscopy, while protein expression was investigated by immunofluorescence imaging and immunoblotting. We found that cellular net acid extrusion increased during human breast carcinogenesis due to enhanced Na(+),HCO3 (-)-cotransport, which created an alkaline shift (~0.3 units of magnitude) in steady-state intracellular pH of human primary breast carcinomas compared to normal breast tissue. Na(+)/H(+)-exchange activity and steady-state intracellular pH in the absence of CO2/HCO3 (-) were practically unaffected by breast carcinogenesis. These effects were evident under both acidic (pH 6.8, representative of the tumor microenvironment) and physiological (pH 7.4) extracellular conditions. Protein expression of the Na(+),HCO3 (-)-cotransporter NBCn1 (SLC4A7), which has been linked to breast cancer susceptibility in multiple genome-wide association studies, was twofold higher in human breast carcinomas compared to matched normal breast tissue. Protein expression of the Na(+)/H(+)-exchanger NHE1 (SLC9A1) was markedly less affected. We propose that upregulated NBCn1 during human breast carcinogenesis contributes to the characteristic acid distribution within human breast carcinomas and thereby plays a pathophysiological role for breast cancer development and progression.
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Affiliation(s)
- Soojung Lee
- Department of Biomedicine, Aarhus University, Ole Worms Allé 3, Building 1170, 8000, Aarhus C, Denmark
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May O, Yu H, Riederer B, Manns MP, Seidler U, Bachmann O. Short-term regulation of murine colonic NBCe1-B (electrogenic Na+/HCO3(-) cotransporter) membrane expression and activity by protein kinase C. PLoS One 2014; 9:e92275. [PMID: 24642792 PMCID: PMC3958514 DOI: 10.1371/journal.pone.0092275] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 02/20/2014] [Indexed: 12/22/2022] Open
Abstract
The colonic mucosa actively secretes HCO3(-), and several lines of evidence point to an important role of Na+/HCO3(-) cotransport (NBC) as a basolateral HCO3(-) import pathway. We could recently demonstrate that the predominant NBC isoform in murine colonic crypts is electrogenic NBCe1-B, and that secretagogues cause NBCe1 exocytosis, which likely represents a component of NBC activation. Since protein kinase C (PKC) plays a key role in the regulation of ion transport by trafficking events, we asked whether it is also involved in the observed NBC activity increase. Crypts were isolated from murine proximal colon to assess PKC activation as well as NBC function and membrane abundance using fluorometric pHi measurements and cell surface biotinylation, respectively. PKC isoform translocation and phosphorylation occurred in response to PMA-, as well as secretagogue stimulation. The conventional and novel PKC inhibitors Gö6976 or Gö6850 did not alter NBC function or surface expression by themselves, but stimulation with forskolin (10(-5) M) or carbachol (10(-4) M) in their presence led to a significant decrease in NBC-mediated proton flux, and biotinylated NBCe1. Our data thus indicate that secretagogues lead to PKC translocation and phosphorylation in murine colonic crypts, and that PKC is necessary for the increase in NBC transport rate and membrane abundance caused by cholinergic and cAMP-dependent stimuli.
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Affiliation(s)
- Oliver May
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Haoyang Yu
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Brigitte Riederer
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Michael P. Manns
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Oliver Bachmann
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
- * E-mail:
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Loh SH, Lee CY, Tsai YT, Shih SJ, Chen LW, Cheng TH, Chang CY, Tsai CS. Intracellular Acid-extruding regulators and the effect of lipopolysaccharide in cultured human renal artery smooth muscle cells. PLoS One 2014; 9:e90273. [PMID: 24587308 PMCID: PMC3931831 DOI: 10.1371/journal.pone.0090273] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 01/31/2014] [Indexed: 12/25/2022] Open
Abstract
Homeostasis of the intracellular pH (pHi) in mammalian cells plays a pivotal role in maintaining cell function. Thus far, the housekeeping Na(+)-H(+) exchanger (NHE) and the Na(+)-HCO3(-) co-transporter (NBC) have been confirmed in many mammalian cells as major acid extruders. However, the role of acid-extruding regulators in human renal artery smooth muscle cells (HRASMCs) remains unclear. It has been demonstrated that lipopolysaccharide (LPS)-induced vascular occlusion is associated with the apoptosis, activating calpain and increased [Ca(2+)]i that are related to NHE1 activity in endothelia cells. This study determines the acid-extruding mechanisms and the effect of LPS on the resting pHi and active acid extruders in cultured HRASMCs. The mechanism of pHi recovery from intracellular acidosis (induced by NH4Cl-prepulse) is determined using BCECF-fluorescence in cultured HRASMCs. It is seen that (a) the resting pHi is 7.19 ± 0.03 and 7.10 ± 0.02 for HEPES- and CO2/HCO3(-)- buffered solution, respectively; (b) apart from the housekeeping NHE1, another Na(+)-coupled HCO3(-) transporter i.e. NBC, functionally co-exists to achieve acid-equivalent extrusion; (c) three different isoforms of NBC: NBCn1 (SLC4A7; electroneutral), NBCe1 (SLC4A4; electrogenic) and NBCe2 (SLC4A5), are detected in protein/mRNA level; and (d) pHi and NHE protein expression/activity are significantly increased by LPS, in both a dose- and time- dependent manner, but NBCs protein expression is not. In conclusion, it is demonstrated, for the first time, that four pHi acid-extruding regulators: NHE1, NBCn1, NBCe1 and NBCe2, co-exist in cultured HRASMCs. LPS also increases cellular growth, pHi and NHE in a dose- and time-dependent manner.
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Affiliation(s)
- Shih-Hurng Loh
- Department of Pharmacology, National Defense Medical Center, Taipei City, Taiwan
- * E-mail:
| | - Chung-Yi Lee
- Department of Cardiovascular Surgery, Tri-Service General Hospital, Taipei, Taiwan
| | - Yi-Ting Tsai
- Department of Cardiovascular Surgery, Tri-Service General Hospital, Taipei, Taiwan
| | - Shou-Jou Shih
- Department of Pharmacology, National Defense Medical Center, Taipei City, Taiwan
| | - Li-Wei Chen
- Department of Pharmacology, National Defense Medical Center, Taipei City, Taiwan
| | - Tzu-Hurng Cheng
- Department of Biological Science and Technology, College of Life Sciences, China Medical University, Taichung, Taiwan
| | - Chung-Yi Chang
- Department of General Surgery, Cheng-Hsieng General Hospital, Taipei, Taiwan
| | - Chein-Sung Tsai
- Department of Cardiovascular Surgery, Tri-Service General Hospital, Taipei, Taiwan
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Abstract
Cell-penetrating peptides (CPPs) have gained attention as promising tools to enable the delivery of various molecules in a non-invasive manner. Among the CPPs, TAT and poly-arginine have been extensively utilized in numerous studies for the delivery of functional proteins, peptides, and macromolecules to analyze cellular signaling. However, the molecular mechanisms of cellular entry remain largely unknown. Here, we applied siRNA library screening to identify the regulatory genes for the cellular entry of poly-arginine peptide based on microscopic observation of the entry of fluorescent peptides in siRNA-treated cells. In this screening, we identified the cell membrane gene SLC4A4 and the trafficking regulator gene COPA, which also plays an important role in early endosome maturation. These results demonstrated that cellular entry of poly-arginine requires at least two different steps, probably binding on the cell surface and endosomal entry. The identification of genes for cellular entry of poly-arginine provides insights into its mechanisms and should further aid in the development of highly efficient cell-penetrating peptides.
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Affiliation(s)
- Tomoyuki Tsumuraya
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Masayuki Matsushita
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
- * E-mail:
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50
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Chinigarzadeh A, Kasim NF, Muniandy S, Kassim NM, Salleh N. Genistein induces increase in fluid pH, Na+ and HCO3(-) concentration, SLC26A6 and SLC4A4 (NBCe1)-B expression in the uteri of ovariectomized rats. Int J Mol Sci 2014; 15:958-76. [PMID: 24434640 PMCID: PMC3907849 DOI: 10.3390/ijms15010958] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Revised: 12/08/2013] [Accepted: 12/29/2013] [Indexed: 12/25/2022] Open
Abstract
Genistein has been reported to stimulate luminal HCO3− secretion. We hypothesized that genistein mediates this effect via SLC26A6 and SLC4A4 (NBCe1) transporters. Our study aimed to: investigate changes in uterine fluid pH, Na+ and HCO3− concentration and expression of uterine SLC26A6 and NBCe1 under genistein effect. Ovariectomized adult female rats received 25, 50 and 100 mg/kg/day genistein for a week with and without ICI 182780. A day after the last injection, in vivo uterine perfusion was performed to collect uterine fluid for Na+, HCO3− and pH determination. The animals were then sacrificed and uteri were removed for mRNA and protein expression analyses. SLC26A6 and NBCe1-A and NBCe1-B distribution were visualized by immunohistochemistry (IHC). Genistein at 50 and 100 mg/kg/day stimulates uterine fluid pH, Na+ and HCO3− concentration increase. Genistein at 100 mg/kg/day up-regulates the expression of SLC26A6 and SLC4A4 mRNA, which were reduced following concomitant ICI 182780 administration. In parallel, SLC26A6 and NBCe1-B protein expression were also increased following high dose genistein treatment and were localized mainly at the apical membrane of the luminal epithelia. SLC26A6 and NBCe1-B up-regulation by genistein could be responsible for the observed increase in the uterine fluid pH, Na+ and HCO3− concentration under this condition.
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Affiliation(s)
- Asma Chinigarzadeh
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur 50603, Malaysia.
| | - Nor Fadila Kasim
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur 50603, Malaysia.
| | - Sekaran Muniandy
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur 50603, Malaysia.
| | - Normadiah M Kassim
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur 50603, Malaysia.
| | - Naguib Salleh
- Department of Physiology, Faculty of Medicine, University of Malaya, Lembah Pantai, Kuala Lumpur 50603, Malaysia.
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