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Horváth V, Garza R, Jönsson ME, Johansson PA, Adami A, Christoforidou G, Karlsson O, Castilla Vallmanya L, Koutounidou S, Gerdes P, Pandiloski N, Douse CH, Jakobsson J. Mini-heterochromatin domains constrain the cis-regulatory impact of SVA transposons in human brain development and disease. Nat Struct Mol Biol 2024:10.1038/s41594-024-01320-8. [PMID: 38834915 DOI: 10.1038/s41594-024-01320-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 04/17/2024] [Indexed: 06/06/2024]
Abstract
SVA (SINE (short interspersed nuclear element)-VNTR (variable number of tandem repeats)-Alu) retrotransposons remain active in humans and contribute to individual genetic variation. Polymorphic SVA alleles harbor gene regulatory potential and can cause genetic disease. However, how SVA insertions are controlled and functionally impact human disease is unknown. Here we dissect the epigenetic regulation and influence of SVAs in cellular models of X-linked dystonia parkinsonism (XDP), a neurodegenerative disorder caused by an SVA insertion at the TAF1 locus. We demonstrate that the KRAB zinc finger protein ZNF91 establishes H3K9me3 and DNA methylation over SVAs, including polymorphic alleles, in human neural progenitor cells. The resulting mini-heterochromatin domains attenuate the cis-regulatory impact of SVAs. This is critical for XDP pathology; removal of local heterochromatin severely aggravates the XDP molecular phenotype, resulting in increased TAF1 intron retention and reduced expression. Our results provide unique mechanistic insights into how human polymorphic transposon insertions are recognized and how their regulatory impact is constrained by an innate epigenetic defense system.
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Affiliation(s)
- Vivien Horváth
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Raquel Garza
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Marie E Jönsson
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Pia A Johansson
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Anita Adami
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Georgia Christoforidou
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
- Laboratory of Epigenetics and Chromatin Dynamics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Ofelia Karlsson
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Laura Castilla Vallmanya
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Symela Koutounidou
- Laboratory of Epigenetics and Chromatin Dynamics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Patricia Gerdes
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Ninoslav Pandiloski
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
- Laboratory of Epigenetics and Chromatin Dynamics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Christopher H Douse
- Laboratory of Epigenetics and Chromatin Dynamics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Johan Jakobsson
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, Lund University, Lund, Sweden.
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Zhang S, Meor Azlan NF, Josiah SS, Zhou J, Zhou X, Jie L, Zhang Y, Dai C, Liang D, Li P, Li Z, Wang Z, Wang Y, Ding K, Wang Y, Zhang J. The role of SLC12A family of cation-chloride cotransporters and drug discovery methodologies. J Pharm Anal 2023; 13:1471-1495. [PMID: 38223443 PMCID: PMC10785268 DOI: 10.1016/j.jpha.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 06/20/2023] [Accepted: 09/05/2023] [Indexed: 09/12/2023] Open
Abstract
The solute carrier family 12 (SLC12) of cation-chloride cotransporters (CCCs) comprises potassium chloride cotransporters (KCCs, e.g. KCC1, KCC2, KCC3, and KCC4)-mediated Cl- extrusion, and sodium potassium chloride cotransporters (N[K]CCs, NKCC1, NKCC2, and NCC)-mediated Cl- loading. The CCCs play vital roles in cell volume regulation and ion homeostasis. Gain-of-function or loss-of-function of these ion transporters can cause diseases in many tissues. In recent years, there have been considerable advances in our understanding of CCCs' control mechanisms in cell volume regulations, with many techniques developed in studying the functions and activities of CCCs. Classic approaches to directly measure CCC activity involve assays that measure the transport of potassium substitutes through the CCCs. These techniques include the ammonium pulse technique, radioactive or nonradioactive rubidium ion uptake-assay, and thallium ion-uptake assay. CCCs' activity can also be indirectly observed by measuring γ-aminobutyric acid (GABA) activity with patch-clamp electrophysiology and intracellular chloride concentration with sensitive microelectrodes, radiotracer 36Cl-, and fluorescent dyes. Other techniques include directly looking at kinase regulatory sites phosphorylation, flame photometry, 22Na+ uptake assay, structural biology, molecular modeling, and high-throughput drug screening. This review summarizes the role of CCCs in genetic disorders and cell volume regulation, current methods applied in studying CCCs biology, and compounds developed that directly or indirectly target the CCCs for disease treatments.
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Affiliation(s)
- Shiyao Zhang
- Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, 363001, China
| | - Nur Farah Meor Azlan
- Institute of Biomedical and Clinical Sciences, Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, EX4 4PS, UK
| | - Sunday Solomon Josiah
- Institute of Biomedical and Clinical Sciences, Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, EX4 4PS, UK
| | - Jing Zhou
- Department of Neurology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institute of Biological Science, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Xiaoxia Zhou
- Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, 363001, China
| | - Lingjun Jie
- Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, 363001, China
| | - Yanhui Zhang
- Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, 363001, China
| | - Cuilian Dai
- Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, 363001, China
| | - Dong Liang
- Aurora Discovery Inc., Foshan, Guangdong, 528300, China
| | - Peifeng Li
- Institute for Translational Medicine, Qingdao University, Qingdao, Shandong, 266021, China
| | - Zhengqiu Li
- School of Pharmacy, Jinan University, Guangzhou, 510632, China
| | - Zhen Wang
- State Key Laboratory of Chemical Biology, Research Center of Chemical Kinomics, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Yun Wang
- Department of Neurology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institute of Biological Science, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Ke Ding
- State Key Laboratory of Chemical Biology, Research Center of Chemical Kinomics, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Yan Wang
- Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, 363001, China
| | - Jinwei Zhang
- Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, Fujian, 363001, China
- Institute of Biomedical and Clinical Sciences, Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, EX4 4PS, UK
- State Key Laboratory of Chemical Biology, Research Center of Chemical Kinomics, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, China
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3
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The Important Role of Ion Transport System in Cervical Cancer. Int J Mol Sci 2021; 23:ijms23010333. [PMID: 35008759 PMCID: PMC8745646 DOI: 10.3390/ijms23010333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 12/26/2021] [Accepted: 12/27/2021] [Indexed: 12/15/2022] Open
Abstract
Cervical cancer is a significant gynecological cancer and causes cancer-related deaths worldwide. Human papillomavirus (HPV) is implicated in the etiology of cervical malignancy. However, much evidence indicates that HPV infection is a necessary but not sufficient cause in cervical carcinogenesis. Therefore, the cellular pathophysiology of cervical cancer is worthy of study. This review summarizes the recent findings concerning the ion transport processes involved in cell volume regulation and intracellular Ca2+ homeostasis of epithelial cells and how these transport systems are themselves regulated by the tumor microenvironment. For cell volume regulation, we focused on the volume-sensitive Cl− channels and K+-Cl− cotransporter (KCC) family, important regulators for ionic and osmotic homeostasis of epithelial cells. Regarding intracellular Ca2+ homeostasis, the Ca2+ store sensor STIM molecules and plasma membrane Ca2+ channel Orai proteins, the predominant Ca2+ entry mechanism in epithelial cells, are discussed. Furthermore, we evaluate the potential of these membrane ion transport systems as diagnostic biomarkers and pharmacological interventions and highlight the challenges.
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Engels M, Kalia M, Rahmati S, Petersilie L, Kovermann P, van Putten MJAM, Rose CR, Meijer HGE, Gensch T, Fahlke C. Glial Chloride Homeostasis Under Transient Ischemic Stress. Front Cell Neurosci 2021; 15:735300. [PMID: 34602981 PMCID: PMC8481871 DOI: 10.3389/fncel.2021.735300] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 08/23/2021] [Indexed: 12/17/2022] Open
Abstract
High water permeabilities permit rapid adjustments of glial volume upon changes in external and internal osmolarity, and pathologically altered intracellular chloride concentrations ([Cl–]int) and glial cell swelling are often assumed to represent early events in ischemia, infections, or traumatic brain injury. Experimental data for glial [Cl–]int are lacking for most brain regions, under normal as well as under pathological conditions. We measured [Cl–]int in hippocampal and neocortical astrocytes and in hippocampal radial glia-like (RGL) cells in acute murine brain slices using fluorescence lifetime imaging microscopy with the chloride-sensitive dye MQAE at room temperature. We observed substantial heterogeneity in baseline [Cl–]int, ranging from 14.0 ± 2.0 mM in neocortical astrocytes to 28.4 ± 3.0 mM in dentate gyrus astrocytes. Chloride accumulation by the Na+-K+-2Cl– cotransporter (NKCC1) and chloride outward transport (efflux) through K+-Cl– cotransporters (KCC1 and KCC3) or excitatory amino acid transporter (EAAT) anion channels control [Cl–]int to variable extent in distinct brain regions. In hippocampal astrocytes, blocking NKCC1 decreased [Cl–]int, whereas KCC or EAAT anion channel inhibition had little effect. In contrast, neocortical astrocytic or RGL [Cl–]int was very sensitive to block of chloride outward transport, but not to NKCC1 inhibition. Mathematical modeling demonstrated that higher numbers of NKCC1 and KCC transporters can account for lower [Cl–]int in neocortical than in hippocampal astrocytes. Energy depletion mimicking ischemia for up to 10 min did not result in pronounced changes in [Cl–]int in any of the tested glial cell types. However, [Cl–]int changes occurred under ischemic conditions after blocking selected anion transporters. We conclude that stimulated chloride accumulation and chloride efflux compensate for each other and prevent glial swelling under transient energy deprivation.
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Affiliation(s)
- Miriam Engels
- Institute of Biological Information Processing, Molekular-und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Manu Kalia
- Applied Analysis, Department of Applied Mathematics, University of Twente, Enschede, Netherlands.,Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sarah Rahmati
- Institute of Biological Information Processing, Molekular-und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Laura Petersilie
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Peter Kovermann
- Institute of Biological Information Processing, Molekular-und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | | | - Christine R Rose
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Hil G E Meijer
- Applied Analysis, Department of Applied Mathematics, University of Twente, Enschede, Netherlands
| | - Thomas Gensch
- Institute of Biological Information Processing, Molekular-und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Christoph Fahlke
- Institute of Biological Information Processing, Molekular-und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
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5
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Flores B, Delpire E. Temporal manipulation of KCC3 expression in juvenile or adult mice suggests irreversible developmental deficit in hereditary motor sensory neuropathy with agenesis of the corpus callosum. Am J Physiol Cell Physiol 2021; 320:C722-C730. [PMID: 33596149 PMCID: PMC8163575 DOI: 10.1152/ajpcell.00594.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 02/16/2021] [Accepted: 02/16/2021] [Indexed: 11/22/2022]
Abstract
Hereditary motor sensory neuropathy (HMSN/ACC) with agenesis of the corpus callosum (ACC) has been documented in the French-derived populations of Charlevoix and Saguenay/Lac St. Jean in Quebec, Canada, as well as a few sporadic families throughout the world. HMSN/ACC occurs because of loss-of-function mutations in the potassium-chloride cotransporter 3 (KCC3). In HMSN/ACC, motor deficits occur early in infancy with rapid and continual deterioration of motor and sensory fibers into juvenile and adulthood. Genetic work in mice has demonstrated that the disease is caused by loss of KCC3 function in neurons and particularly parvalbumin (PV)-expressing neurons. Currently, there are no treatments or cures for HMSN/ACC other than pain management. As genetic counseling in Quebec has increased as a preventative strategy, most individuals with HSMN/ACC are now adults. The onset of the disease is unknown. In particular, it is unknown if the disease starts early during development and whether it can be reversed by restoring KCC3 function. In this study, we used two separate mouse models that when combined to the PV-CreERT2 tamoxifen-inducible system allowed us to 1) disrupt KCC3 expression in adulthood or juvenile periods; and 2) reintroduce KCC3 expression in mice that first develop with a nonfunctional cotransporter. We show that disrupting or reintroducing KCC3 in the adult mouse has no effect on locomotor behavior, indicating that expression of KCC3 is critical during embryonic development and/or the perinatal period and that once the disease has started, reexpressing a functional cotransporter fails to change the course of HMSN/ACC.
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Affiliation(s)
- Bianca Flores
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee
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Meor Azlan NF, Zhang J. Role of the Cation-Chloride-Cotransporters in Cardiovascular Disease. Cells 2020; 9:E2293. [PMID: 33066544 PMCID: PMC7602155 DOI: 10.3390/cells9102293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/08/2020] [Accepted: 10/14/2020] [Indexed: 02/05/2023] Open
Abstract
The SLC12 family of cation-chloride-cotransporters (CCCs) is comprised of potassium chloride cotransporters (KCCs), which mediate Cl- extrusion and sodium-potassium chloride cotransporters (N[K]CCs), which mediate Cl- loading. The CCCs play vital roles in cell volume regulation and ion homeostasis. The functions of CCCs influence a variety of physiological processes, many of which overlap with the pathophysiology of cardiovascular disease. Although not all of the cotransporters have been linked to Mendelian genetic disorders, recent studies have provided new insights into their functional role in vascular and renal cells in addition to their contribution to cardiovascular diseases. Particularly, an imbalance in potassium levels promotes the pathogenesis of atherosclerosis and disturbances in sodium homeostasis are one of the causes of hypertension. Recent findings suggest hypothalamic signaling as a key signaling pathway in the pathophysiology of hypertension. In this review, we summarize and discuss the role of CCCs in cardiovascular disease with particular emphasis on knowledge gained in recent years on NKCCs and KCCs.
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Affiliation(s)
- Nur Farah Meor Azlan
- Institute of Biomedical and Clinical Sciences, Medical School, College of Medicine and Health, Hatherly Laboratories, University of Exeter, Exeter EX4 4PS, UK;
| | - Jinwei Zhang
- Institute of Biomedical and Clinical Sciences, Medical School, College of Medicine and Health, Hatherly Laboratories, University of Exeter, Exeter EX4 4PS, UK;
- Xiamen Cardiovascular Hospital, School of Medicine, Xiamen University, Xiamen 361004, Fujian, China
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7
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Angileri F, Legare S, Marino Gammazza A, Conway de Macario E, Jl Macario A, Cappello F. Molecular mimicry may explain multi-organ damage in COVID-19. Autoimmun Rev 2020; 19:102591. [PMID: 32535095 PMCID: PMC7289093 DOI: 10.1016/j.autrev.2020.102591] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 05/18/2020] [Indexed: 12/22/2022]
Affiliation(s)
- Francesca Angileri
- Université de Lyon, Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Cancer Research Center of Lyon, Lyon, France
| | - Sébastien Legare
- Département d'Informatique de l'ÉNS, ÉNS, CNRS, Université PSL, Paris, France; Centre de recherche Inria de Paris, Paris, France
| | - Antonella Marino Gammazza
- University of Palermo, Department of Biomedicine, Neuroscience and Advanced Diagnostics (BIND), Palermo, Italy
| | - Everly Conway de Macario
- Department of Microbiology and Immunology, School of Medicine, University of Maryland at Baltimore-Institute of Marine and Environmental Technology (IMET), Baltimore, MD 21202, USA
| | - Alberto Jl Macario
- Department of Microbiology and Immunology, School of Medicine, University of Maryland at Baltimore-Institute of Marine and Environmental Technology (IMET), Baltimore, MD 21202, USA; Euro-Mediterranean Institute of Science and Technology (IEMEST), Palermo, Italy
| | - Francesco Cappello
- University of Palermo, Department of Biomedicine, Neuroscience and Advanced Diagnostics (BIND), Palermo, Italy; Euro-Mediterranean Institute of Science and Technology (IEMEST), Palermo, Italy.
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8
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Lanni JS, Peal D, Ekstrom L, Chen H, Stanclift C, Bowen ME, Mercado A, Gamba G, Kahle KT, Harris MP. Integrated K+ channel and K+Cl- cotransporter functions are required for the coordination of size and proportion during development. Dev Biol 2019; 456:164-178. [PMID: 31472116 PMCID: PMC7235970 DOI: 10.1016/j.ydbio.2019.08.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 08/07/2019] [Accepted: 08/23/2019] [Indexed: 10/26/2022]
Abstract
The coordination of growth during development establishes proportionality within and among the different anatomic structures of organisms. Innate memory of this proportionality is preserved, as shown in the ability of regenerating structures to return to their original size. Although the regulation of this coordination is incompletely understood, mutant analyses of zebrafish with long-finned phenotypes have uncovered important roles for bioelectric signaling in modulating growth and size of the fins and barbs. To date, long-finned mutants identified are caused by hypermorphic mutations, leaving unresolved whether such signaling is required for normal development. We isolated a new zebrafish mutant, schleier, with proportional overgrowth phenotypes caused by a missense mutation and loss of function in the K+-Cl- cotransporter Kcc4a. Creation of dominant negative Kcc4a in wild-type fish leads to loss of growth restriction in fins and barbs, supporting a requirement for Kcc4a in regulation of proportion. Epistasis experiments suggest that Kcc4a and the two-pore potassium channel Kcnk5b both contribute to a common bioelectrical signaling response in the fin. These data suggest that an integrated bioelectric signaling pathway is required for the coordination of size and proportion during development.
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Affiliation(s)
| | - David Peal
- Department of Genetics, Harvard Medical School, Boston, MA, 02124, USA; Department of Orthopaedic Research, Boston Children's Hospital, Boston, MA, 02124, USA
| | - Laura Ekstrom
- Department of Biology, Wheaton College, Norton, MA, 02766, USA
| | - Haining Chen
- Department of Biology, Wheaton College, Norton, MA, 02766, USA
| | | | - Margot E Bowen
- Department of Genetics, Harvard Medical School, Boston, MA, 02124, USA; Department of Orthopaedic Research, Boston Children's Hospital, Boston, MA, 02124, USA
| | | | - Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico; Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Mexico
| | - Kristopher T Kahle
- Departments of Neurosurgery, Pediatrics, and Cellular & Molecular Physiology, and NIH-Rockefeller Center for Mendelian Genomics, Yale School of Medicine, New Haven, CT, 06511, USA
| | - Matthew P Harris
- Department of Genetics, Harvard Medical School, Boston, MA, 02124, USA; Department of Orthopaedic Research, Boston Children's Hospital, Boston, MA, 02124, USA
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9
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Tyrosine phosphorylation modulates cell surface expression of chloride cotransporters NKCC2 and KCC3. Arch Biochem Biophys 2019; 669:61-70. [PMID: 31145900 DOI: 10.1016/j.abb.2019.05.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 05/24/2019] [Accepted: 05/26/2019] [Indexed: 11/22/2022]
Abstract
Cellular chloride transport has a fundamental role in cell volume regulation and renal salt handling. Cellular chloride entry or exit are mediated at the plasma membrane by cotransporter proteins of the solute carrier 12 family. For example, NKCC2 resorbs chloride with sodium and potassium ions at the apical membrane of epithelial cells in the kidney, whereas KCC3 releases chloride with potassium ions at the basolateral membrane. Their ion transport activity is regulated by protein phosphorylation in response to signaling pathways. An additional regulatory mechanism concerns the amount of cotransporter molecules inserted into the plasma membrane. Here we describe that tyrosine phosphorylation of NKCC2 and KCC3 regulates their plasma membrane expression levels. We identified that spleen tyrosine kinase (SYK) phosphorylates a specific N-terminal tyrosine residue in each cotransporter. Experimental depletion of endogenous SYK or pharmacological inhibition of its kinase activity increased the abundance of NKCC2 at the plasma membrane of human embryonic kidney cells. In contrast, overexpression of a constitutively active SYK mutant decreased NKCC2 membrane abundance. Intriguingly, the same experimental approaches revealed the opposite effect on KCC3 abundance at the plasma membrane, compatible with the known antagonistic roles of NKCC and KCC cotransporters in cell volume regulation. Thus, we identified a novel pathway modulating the cell surface expression of NKCC2 and KCC3 and show that this same pathway has opposite functional outcomes for these two cotransporters. The findings have several biomedical implications considering the role of these cotransporters in regulating blood pressure and cell volume.
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10
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Mero M, Asraf H, Sekler I, Taylor KM, Hershfinkel M. ZnR/GPR39 upregulation of K +/Cl --cotransporter 3 in tamoxifen resistant breast cancer cells. Cell Calcium 2019; 81:12-20. [PMID: 31146164 DOI: 10.1016/j.ceca.2019.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 05/20/2019] [Accepted: 05/20/2019] [Indexed: 01/01/2023]
Abstract
Expression of the zinc receptor, ZnR/GPR39, is increased in higher grade breast cancer tumors and cells. Zinc, its ligand, is accumulated at larger concentrations in the tumor tissue and can therefore activate ZnR/GPR39-dependent Ca2+ signaling leading to tumor progression. The K+/Cl- co-transporters (KCC), activated by intracellular signaling, enhance breast cancer cell migration and invasion. We asked if ZnR/GPR39 enhances breast cancer cell malignancy by activating KCC. Activation of ZnR/GPR39 by Zn2+ upregulated K+/Cl- co-transport activity, measured using NH4+ as a surrogate to K+ while monitoring intracellular pH. Upregulation of NH4+ transport was monitored in tamoxifen resistant cells with functional ZnR/GPR39-dependent Ca2+ signaling but not in MCF-7 cells lacking this response. The NH4+ transport was Na+-independent, and we therefore focused on KCC family members. Silencing of KCC3, but not KCC4, expression abolished Zn2+-dependent K+/Cl- co-transport, suggesting that KCC3 is mediating upregulated NH4+ transport. The ZnR/GPR39-dependent KCC3 activation accelerated scratch closure rate, which was abolished by inhibiting KCC transport with [(DihydroIndenyl) Oxy] Alkanoic acid (DIOA). Importantly, silencing of either ZnR/GPR39 or KCC3 attenuated Zn2+-dependent scratch closure. Thus, a novel link between KCC3 and Zn2+, via ZnR/GPR39, promotes breast cancer cell migration and proliferation.
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Affiliation(s)
- Maayan Mero
- Department of Physiology and Cell Biology and The Zlotowski Center for Neuroscience, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Hila Asraf
- Department of Physiology and Cell Biology and The Zlotowski Center for Neuroscience, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Israel Sekler
- Department of Physiology and Cell Biology and The Zlotowski Center for Neuroscience, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Kathryn M Taylor
- Breast Cancer Molecular Pharmacology Group, School of Pharmacy and Pharmaceutical Sciences, Redwood Building, Cardiff University, King Edward VII Avenue, Cardiff, CF10 3NB, UK
| | - Michal Hershfinkel
- Department of Physiology and Cell Biology and The Zlotowski Center for Neuroscience, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
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11
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Lauf PK, Sharma N, Adragna NC. Kinetic studies of K-Cl cotransport in cultured rat vascular smooth muscle cells. Am J Physiol Cell Physiol 2019; 316:C274-C284. [PMID: 30649919 DOI: 10.1152/ajpcell.00002.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
During aging, and development of atherosclerosis and cardiovascular disease (CVD), aortic vascular smooth muscle cells (VSMCs) transition from healthy contractile to diseased synthetic phenotypes. K-Cl cotransport (KCC) maintains cell volume and ion homeostasis in growth and differentiation, and hence is important for VSMC proliferation and migration. Therefore, KCC activity may play a role in the contractile-to-synthetic VSMC phenotypic transition. Early, medium, and late synthetic passage VSMCs were tested for specific cytoskeletal protein expression. KCC-mediated ouabain- and bumetanide-insensitive Rb+ (a K+ congener) influx was determined as Cl--dependent Rb+ influx at different external Rb+ and Cl- ion concentrations, [Rb+]o and [Cl-]o. Expressions of the cytoskeletal proteins α-actin, vimentin, and desmin fell from early through late synthetic VSMCs. KCC kinetic parameters, such as maximum velocity ( Vm), and apparent Cl- and Rb+ affinities ( Km), were calculated with Lineweaver-Burk, Hanes-Woolf, and Hill approximations. Vm values of both Rb+- and Cl--dependent influxes were of equal magnitude, commensurate with a KCC stoichiometry of unity, and rose threefold from early to late synthetic VSMCs. Hill coefficients for Rb+ and Cl- correlated with cell passage number, suggesting increased KCC ligand cooperativity. However, Km values for [Cl-]o were strikingly bimodal with 60-80 mM in early, ~20-30 mM in medium, and 60 mM in late passage cells. In contrast, Km values for [Rb+]o remained steady at ~17 mM. Since total KCC isoform expression was similar with cell passage, structure/function changes of the KCC signalosome may accompany the transition of aortic VSMCs from a healthy to a diseased phenotype.
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Affiliation(s)
- Peter K Lauf
- The Cell Biophysics Group, Wright State University , Dayton, Ohio
- Department of Pharmacology and Toxicology, Wright State University , Dayton, Ohio
- Department of Pathology, Wright State University , Dayton, Ohio
- Boonshoft School of Medicine, Wright State University , Dayton, Ohio
| | - Neelima Sharma
- The Cell Biophysics Group, Wright State University , Dayton, Ohio
- Department of Pharmacology and Toxicology, Wright State University , Dayton, Ohio
- Boonshoft School of Medicine, Wright State University , Dayton, Ohio
| | - Norma C Adragna
- The Cell Biophysics Group, Wright State University , Dayton, Ohio
- Department of Pharmacology and Toxicology, Wright State University , Dayton, Ohio
- Boonshoft School of Medicine, Wright State University , Dayton, Ohio
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12
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Conway LC, Cardarelli RA, Moore YE, Jones K, McWilliams LJ, Baker DJ, Burnham MP, Bürli RW, Wang Q, Brandon NJ, Moss SJ, Deeb TZ. N-Ethylmaleimide increases KCC2 cotransporter activity by modulating transporter phosphorylation. J Biol Chem 2017; 292:21253-21263. [PMID: 29092909 PMCID: PMC5766942 DOI: 10.1074/jbc.m117.817841] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 10/27/2017] [Indexed: 11/06/2022] Open
Abstract
K+/Cl- cotransporter 2 (KCC2) is selectively expressed in the adult nervous system and allows neurons to maintain low intracellular Cl- levels. Thus, KCC2 activity is an essential prerequisite for fast hyperpolarizing synaptic inhibition mediated by type A γ-aminobutyric acid (GABAA) receptors, which are Cl--permeable, ligand-gated ion channels. Consistent with this, deficits in the activity of KCC2 lead to epilepsy and are also implicated in neurodevelopmental disorders, neuropathic pain, and schizophrenia. Accordingly, there is significant interest in developing activators of KCC2 as therapeutic agents. To provide insights into the cellular processes that determine KCC2 activity, we have investigated the mechanism by which N-ethylmaleimide (NEM) enhances transporter activity using a combination of biochemical and electrophysiological approaches. Our results revealed that, within 15 min, NEM increased cell surface levels of KCC2 and modulated the phosphorylation of key regulatory residues within the large cytoplasmic domain of KCC2 in neurons. More specifically, NEM increased the phosphorylation of serine 940 (Ser-940), whereas it decreased phosphorylation of threonine 1007 (Thr-1007). NEM also reduced with no lysine (WNK) kinase phosphorylation of Ste20-related proline/alanine-rich kinase (SPAK), a kinase that directly phosphorylates KCC2 at residue Thr-1007. Mutational analysis revealed that Thr-1007 dephosphorylation mediated the effects of NEM on KCC2 activity. Collectively, our results suggest that compounds that either increase the surface stability of KCC2 or reduce Thr-1007 phosphorylation may be of use as enhancers of KCC2 activity.
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Affiliation(s)
- Leslie C Conway
- From the AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, Massachusetts 02111
| | - Ross A Cardarelli
- From the AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, Massachusetts 02111
| | - Yvonne E Moore
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Karen Jones
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Alderley Park SK10 4TG, United Kingdom
| | - Lisa J McWilliams
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Cambridge CB4 0WG, United Kingdom
| | - David J Baker
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Cambridge CB4 0WG, United Kingdom
| | - Matthew P Burnham
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Alderley Park SK10 4TG, United Kingdom
| | - Roland W Bürli
- Neuroscience, IMED Biotech Unit, AstraZeneca, Cambridge CB21 6GH, United Kingdom, and
| | - Qi Wang
- From the AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, Massachusetts 02111
- Neuroscience, IMED Biotech Unit, AstraZeneca, Boston, Massachusetts 02451
| | - Nicholas J Brandon
- From the AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, Massachusetts 02111
- Neuroscience, IMED Biotech Unit, AstraZeneca, Boston, Massachusetts 02451
| | - Stephen J Moss
- From the AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, Massachusetts 02111,
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Tarek Z Deeb
- From the AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, Massachusetts 02111
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111
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13
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Molecular features and physiological roles of K +-Cl - cotransporter 4 (KCC4). Biochim Biophys Acta Gen Subj 2017; 1861:3154-3166. [PMID: 28935604 DOI: 10.1016/j.bbagen.2017.09.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/15/2017] [Indexed: 12/27/2022]
Abstract
A K+-Cl- cotransport system was documented for the first time during the mid-seventies in sheep and goat red blood cells. It was then described as a Na+-independent and ouabain-insensitive ion carrier that could be stimulated by cell swelling and N-ethylmaleimide (NEM), a thiol-reacting agent. Twenty years later, this system was found to be dispensed by four different isoforms in animal cells. The first one was identified in the expressed sequence tag (EST) database by Gillen et al. based on the assumption that it would be homologous to the Na+-dependent K+-Cl- cotransport system for which the molecular identity had already been uncovered. Not long after, the three other isoforms were once again identified in the EST databank. Among those, KCC4 has generated much interest a few years ago when it was shown to sustain distal renal acidification and hearing development in mouse. As will be seen in this review, many additional roles were ascribed to this isoform, in keeping with its wide distribution in animal species. However, some of them have still not been confirmed through animal models of gene inactivation or overexpression. Along the same line, considerable knowledge has been acquired on the mechanisms by which KCC4 is regulated and the environmental cues to which it is sensitive. Yet, it is inferred to some extent from historical views and extrapolations.
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14
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Ludwig A, Rivera C, Uvarov P. A noninvasive optical approach for assessing chloride extrusion activity of the K-Cl cotransporter KCC2 in neuronal cells. BMC Neurosci 2017; 18:23. [PMID: 28143398 PMCID: PMC5286847 DOI: 10.1186/s12868-017-0336-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 01/12/2017] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Cation-chloride cotransporters (CCCs) are indispensable for maintaining chloride homeostasis in multiple cell types, but K-Cl cotransporter KCC2 is the only CCC member with an exclusively neuronal expression in mammals. KCC2 is critical for rendering fast hyperpolarizing responses of ionotropic γ-aminobutyric acid and glycine receptors in adult neurons, for neuronal migration in the developing central nervous system, and for the formation and maintenance of small dendritic protrusions-dendritic spines. Deficit in KCC2 expression and/or activity is associated with epilepsy and neuropathic pain, and effective strategies are required to search for novel drugs augmenting KCC2 function. RESULTS We revised current methods to develop a noninvasive optical approach for assessing KCC2 transport activity using a previously characterized genetically encoded chloride sensor. Our protocol directly assesses dynamics of KCC2-mediated chloride efflux and allows measuring genuine KCC2 activity with good spatial and temporal resolution. As a proof of concept, we used this approach to compare transport activities of the two known KCC2 splice isoforms, KCC2a and KCC2b, in mouse neuronal Neuro-2a cells. CONCLUSIONS Our noninvasive optical protocol proved to be efficient for assessment of furosemide-sensitive chloride fluxes. Transport activities of the N-terminal splice isoforms KCC2a and KCC2b obtained by the novel approach matched to those reported previously using standard methods for measuring chloride fluxes.
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Affiliation(s)
- Anastasia Ludwig
- Neuroscience Center, University of Helsinki, Helsinki, Finland
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM U1024, CNRS 8197, Paris, France
| | - Claudio Rivera
- Neuroscience Center, University of Helsinki, Helsinki, Finland
- INSERM U901, Institut de Neurobiologie de la Méditerranée (INMED), Marseille, France
- UMR S901, Aix-Marseille Université, Marseille, France
| | - Pavel Uvarov
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Biosciences and Neuroscience Center, University of Helsinki, Helsinki, Finland
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15
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Mercado A, de Los Heros P, Melo Z, Chávez-Canales M, Murillo-de-Ozores AR, Moreno E, Bazúa-Valenti S, Vázquez N, Hadchouel J, Gamba G. With no lysine L-WNK1 isoforms are negative regulators of the K+-Cl- cotransporters. Am J Physiol Cell Physiol 2016; 311:C54-66. [PMID: 27170636 PMCID: PMC4967140 DOI: 10.1152/ajpcell.00193.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 05/02/2016] [Indexed: 12/11/2022]
Abstract
The K(+)-Cl(-) cotransporters (KCC1-KCC4) encompass a branch of the SLC12 family of electroneutral cation-coupled chloride cotransporters that translocate ions out of the cell to regulate various factors, including cell volume and intracellular chloride concentration, among others. L-WNK1 is an ubiquitously expressed kinase that is activated in response to osmotic stress and intracellular chloride depletion, and it is implicated in two distinct hereditary syndromes: the renal disease pseudohypoaldosteronism type II (PHAII) and the neurological disease hereditary sensory neuropathy 2 (HSN2). The effect of L-WNK1 on KCC activity is unknown. Using Xenopus laevis oocytes and HEK-293 cells, we show that the activation of KCCs by cell swelling was prevented by L-WNK1 coexpression. In contrast, the activity of the Na(+)-K(+)-2Cl(-) cotransporter NKCC1 was remarkably increased with L-WNK1 coexpression. The negative effect of L-WNK1 on the KCCs is kinase dependent. Elimination of the STE20 proline-alanine rich kinase (SPAK)/oxidative stress-responsive kinase (OSR1) binding site or the HQ motif required for the WNK-WNK interaction prevented the effect of L-WNK1 on KCCs, suggesting a required interaction between L-WNK1 molecules and SPAK. Together, our data support that NKCC1 and KCCs are coordinately regulated by L-WNK1 isoforms.
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Affiliation(s)
- Adriana Mercado
- Department of Nephrology, Instituto Nacional de Cardiología Ignacio Chávez, Tlalpan, Mexico City, Mexico
| | - Paola de Los Heros
- División de Investigación, Facultad de Medicina, Universidad Nacional Autónoma de México, Coyoacán, Mexico City, Mexico
| | - Zesergio Melo
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico
| | - María Chávez-Canales
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico; Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán. Tlalpan, Mexico City, Mexico; INSERM UMR970-Paris Cardiovascular Research Center, Paris, France; and University Paris-Descartes, Sorbonne Paris Cité, Faculty of Medicine, Paris, France
| | - Adrián R Murillo-de-Ozores
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico
| | - Erika Moreno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán. Tlalpan, Mexico City, Mexico
| | - Silvana Bazúa-Valenti
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico; Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán. Tlalpan, Mexico City, Mexico
| | - Norma Vázquez
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico; Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán. Tlalpan, Mexico City, Mexico
| | - Juliette Hadchouel
- INSERM UMR970-Paris Cardiovascular Research Center, Paris, France; and University Paris-Descartes, Sorbonne Paris Cité, Faculty of Medicine, Paris, France
| | - Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico; Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán. Tlalpan, Mexico City, Mexico;
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16
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Dbouk HA, Huang CL, Cobb MH. Hypertension: the missing WNKs. Am J Physiol Renal Physiol 2016; 311:F16-27. [PMID: 27009339 PMCID: PMC4967160 DOI: 10.1152/ajprenal.00358.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 03/16/2016] [Indexed: 12/23/2022] Open
Abstract
The With no Lysine [K] (WNK) family of enzymes are central in the regulation of blood pressure. WNKs have been implicated in hereditary hypertension disorders, mainly through control of the activity and levels of ion cotransporters and channels. Actions of WNKs in the kidney have been heavily investigated, and recent studies have provided insight into not only the regulation of these enzymes but also how mutations in WNKs and their interacting partners contribute to hypertensive disorders. Defining the roles of WNKs in the cardiovascular system will provide clues about additional mechanisms by which WNKs can regulate blood pressure. This review summarizes recent developments in the regulation of the WNK signaling cascade and its role in regulation of blood pressure.
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Affiliation(s)
- Hashem A Dbouk
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Chou-Long Huang
- Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Melanie H Cobb
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas; and
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17
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Heidari M, Gerami SH, Bassett B, Graham RM, Chua ACG, Aryal R, House MJ, Collingwood JF, Bettencourt C, Houlden H, Ryten M, Olynyk JK, Trinder D, Johnstone DM, Milward EA. Pathological relationships involving iron and myelin may constitute a shared mechanism linking various rare and common brain diseases. Rare Dis 2016; 4:e1198458. [PMID: 27500074 PMCID: PMC4961263 DOI: 10.1080/21675511.2016.1198458] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/02/2016] [Accepted: 06/01/2016] [Indexed: 12/18/2022] Open
Abstract
We previously demonstrated elevated brain iron levels in myelinated structures and associated cells in a hemochromatosis Hfe−/−xTfr2mut mouse model. This was accompanied by altered expression of a group of myelin-related genes, including a suite of genes causatively linked to the rare disease family ‘neurodegeneration with brain iron accumulation’ (NBIA). Expanded data mining and ontological analyses have now identified additional myelin-related transcriptome changes in response to brain iron loading. Concordance between the mouse transcriptome changes and human myelin-related gene expression networks in normal and NBIA basal ganglia testifies to potential clinical relevance. These analyses implicate, among others, genes linked to various rare central hypomyelinating leukodystrophies and peripheral neuropathies including Pelizaeus-Merzbacher-like disease and Charcot-Marie-Tooth disease as well as genes linked to other rare neurological diseases such as Niemann-Pick disease. The findings may help understand interrelationships of iron and myelin in more common conditions such as hemochromatosis, multiple sclerosis and various psychiatric disorders.
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Affiliation(s)
- Moones Heidari
- School of Biomedical Sciences and Pharmacy, The University of Newcastle , Callaghan, NSW, Australia
| | - Sam H Gerami
- School of Biomedical Sciences and Pharmacy, The University of Newcastle , Callaghan, NSW, Australia
| | - Brianna Bassett
- School of Biomedical Sciences and Pharmacy, The University of Newcastle , Callaghan, NSW, Australia
| | - Ross M Graham
- School of Biomedical Sciences & Curtin Health Innovation Research Institute - Biosciences, Curtin University of Technology , Bentley, WA, Australia
| | - Anita C G Chua
- School of Medicine and Pharmacology, University of Western Australia, Fiona Stanley Hospital, Murdoch, WA, Australia; Harry Perkins Institute of Medical Research, Murdoch, WA, Australia
| | - Ritambhara Aryal
- School of Biomedical Sciences and Pharmacy, The University of Newcastle , Callaghan, NSW, Australia
| | - Michael J House
- School of Physics, University of Western Australia , Crawley, WA, Australia
| | - Joanna F Collingwood
- Warwick Engineering in Biomedicine, School of Engineering, University of Warwick , Coventry, UK
| | - Conceição Bettencourt
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK; Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
| | - Henry Houlden
- Department of Molecular Neuroscience, UCL Institute of Neurology , London, UK
| | - Mina Ryten
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK; Department of Medical and Molecular Genetics, King's College London, London, UK
| | | | - John K Olynyk
- School of Biomedical Sciences & Curtin Health Innovation Research Institute - Biosciences, Curtin University of Technology, Bentley, WA, Australia; Institute for Immunology and Infectious Diseases, Murdoch University, Perth, WA, Australia; Department of Gastroenterology and Hepatology, Fiona Stanley Hospital, Murdoch, WA, Australia; Department of Gastroenterology and Hepatology, Fremantle Hospital, Fremantle, WA, Australia
| | - Debbie Trinder
- School of Medicine and Pharmacology, University of Western Australia, Fiona Stanley Hospital, Murdoch, WA, Australia; Harry Perkins Institute of Medical Research, Murdoch, WA, Australia
| | - Daniel M Johnstone
- Bosch Institute and Discipline of Physiology, University of Sydney , Sydney, NSW, Australia
| | - Elizabeth A Milward
- School of Biomedical Sciences and Pharmacy, The University of Newcastle , Callaghan, NSW, Australia
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18
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Basak D, Sridhar S, Bera AK, Madhavan N. Cation–halide transport through peptide pores containing aminopicolinic acid. Org Biomol Chem 2016; 14:4712-7. [DOI: 10.1039/c6ob00592f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aminopicolinic acid incorporated peptides form pores that promote cation–halide co-transport across lipid bilayers and do not show a closed state.
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Affiliation(s)
- Debajyoti Basak
- Department of Chemistry
- Indian institute of Technology
- Chennai 600036
- India
| | - Sucheta Sridhar
- Department of Biotechnology
- Indian institute of Technology
- Chennai 600036
- India
| | - Amal K. Bera
- Department of Biotechnology
- Indian institute of Technology
- Chennai 600036
- India
| | - Nandita Madhavan
- Department of Chemistry
- Indian institute of Technology
- Chennai 600036
- India
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19
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Brown FC, Conway AJ, Cerruti L, Collinge JE, McLean C, Wiley JS, Kile BT, Jane SM, Curtis DJ. Activation of the erythroid K-Cl cotransporter Kcc1 enhances sickle cell disease pathology in a humanized mouse model. Blood 2015; 126:2863-70. [PMID: 26450986 DOI: 10.1182/blood-2014-10-609362] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 09/24/2015] [Indexed: 12/18/2022] Open
Abstract
We used an N-ethyl-N-nitrosurea-based forward genetic screen in mice to identify new genes and alleles that regulate erythropoiesis. Here, we describe a mouse line expressing an activated form of the K-Cl cotransporter Slc12a4 (Kcc1), which results in a semi-dominant microcytosis of red cells. A missense mutation from methionine to lysine in the cytoplasmic tail of Kcc1 impairs phosphorylation of adjacent threonines required for inhibiting cotransporter activity. We bred Kcc1(M935K) mutant mice with a humanized mouse model of sickle cell disease to directly explore the relevance of the reported increase in KCC activity in disease pathogenesis. We show that a single mutant allele of Kcc1 induces widespread sickling and tissue damage, leading to premature death. This mouse model reveals important new insights into the regulation of K-Cl cotransporters and provides in vivo evidence that increased KCC activity worsened end-organ damage and diminished survival in sickle cell disease.
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Affiliation(s)
- Fiona C Brown
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Australia
| | - Ashlee J Conway
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Australia
| | - Loretta Cerruti
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Australia
| | - Janelle E Collinge
- Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | | | - James S Wiley
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Australia; and
| | - Ben T Kile
- Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Stephen M Jane
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Australia; The Alfred Hospital, Melbourne, Australia; Department of Medicine, Central Clinical School, Monash University, Melbourne, Australia
| | - David J Curtis
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Australia; The Alfred Hospital, Melbourne, Australia
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20
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Park IS, Lee J, Lee G, Nam K, Lee T, Chang WJ, Kim H, Lee SY, Seo J, Yoon DS, Lee SW. Real-Time Analysis of Cellular Response to Small-Molecule Drugs within a Microfluidic Dielectrophoresis Device. Anal Chem 2015; 87:5914-20. [PMID: 25811309 DOI: 10.1021/ac5041549] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quantitative detection of the biological properties of living cells is essential for a wide range of purposes, from the understanding of cellular characteristics to the development of novel drugs in nanomedicine. Here, we demonstrate that analysis of cell biological properties within a microfluidic dielectrophoresis device enables quantitative detection of cellular biological properties and simultaneously allows large-scale measurement in a noise-robust and probeless manner. Applying this technique, the static and dynamic biological responses of live B16F10 melanoma cells to the small-molecule drugs such as N-ethylmaleimide (NEM) and [(dihydronindenyl)oxy]alkanoic acid (DIOA) were quantitatively and statistically examined by investigating changes in movement of the cells. Measurement was achieved using subtle variations in dielectrophoresis (DEP) properties of the cells, which were attributed to activation or deactivation of K(+)/Cl(-) cotransporter channels on the cell membrane by the small-molecule drugs, in a microfluidic device. On the basis of quantitative analysis data, we also provide the first report of the shift of the complex permittivity of a cell induced by the small-molecule drugs. In addition, we demonstrate interesting quantifiable parameters including the drug effectiveness coefficient, antagonistic interaction coefficient, kinetic rate, and full width at half-maximum, which corresponded to changes in biological properties of B16F10 cells over time when NEM and DIOA were introduced alone or in combination. Those demonstrated parameters represent very useful tools for evaluating the effect of small-molecule drugs on the biological properties of cells.
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Affiliation(s)
- In Soo Park
- †Department of Biomedical Engineering, Yonsei University, Wonju 220-710, Republic of Korea
| | - Jaewoo Lee
- †Department of Biomedical Engineering, Yonsei University, Wonju 220-710, Republic of Korea
| | - Gyudo Lee
- †Department of Biomedical Engineering, Yonsei University, Wonju 220-710, Republic of Korea
- ∥T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts 02115, United States
| | - Kihwan Nam
- †Department of Biomedical Engineering, Yonsei University, Wonju 220-710, Republic of Korea
| | - Taewoo Lee
- †Department of Biomedical Engineering, Yonsei University, Wonju 220-710, Republic of Korea
| | - Woo-Jin Chang
- ‡Department of Mechanical Engineering and Great Lakes WATER Institute, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Hansung Kim
- †Department of Biomedical Engineering, Yonsei University, Wonju 220-710, Republic of Korea
| | - Sei-Young Lee
- †Department of Biomedical Engineering, Yonsei University, Wonju 220-710, Republic of Korea
| | - Jongbum Seo
- †Department of Biomedical Engineering, Yonsei University, Wonju 220-710, Republic of Korea
| | - Dae Sung Yoon
- §School of Biomedical Engineering, Korea University, Seoul, 136-703, Republic of Korea
| | - Sang Woo Lee
- †Department of Biomedical Engineering, Yonsei University, Wonju 220-710, Republic of Korea
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21
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The K-Cl cotransporter KCC3 as an independent prognostic factor in human esophageal squamous cell carcinoma. BIOMED RESEARCH INTERNATIONAL 2014; 2014:936401. [PMID: 25110711 PMCID: PMC4119626 DOI: 10.1155/2014/936401] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 06/16/2014] [Indexed: 01/02/2023]
Abstract
The objectives of the present study were to investigate the role of K–Cl cotransporter 3 (KCC3) in the regulation of cellular invasion and the clinicopathological significance of its expression in esophageal squamous cell carcinoma (ESCC). Immunohistochemical analysis performed on 70 primary tumor samples obtained from ESCC patients showed that KCC3 was primarily found in the cytoplasm of carcinoma cells. Although the expression of KCC3 in the main tumor (MT) was related to several clinicopathological features, such as the pT and pN categories, it had no prognostic impact. KCC3 expression scores were compared between the MT and cancer nest (CN), and the survival rate of patients with a CN > MT score was lower than that of patients with a CN ≤ MT score. In addition, the survival rate of patients in whom KCC3 was expressed in the invasive front of tumor was lower than that of the patients without it. Furthermore, multivariate analysis demonstrated that the expression of KCC3 in the invasive front was one of the most important independent prognostic factors. The depletion of KCC3 using siRNAs inhibited cell migration and invasion in human ESCC cell lines. These results suggest that the expression of KCC3 in ESCC may affect cellular invasion and be related to a worse prognosis in patients with ESCC.
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Chiu MH, Liu HS, Wu YH, Shen MR, Chou CY. SPAK mediates KCC3-enhanced cervical cancer tumorigenesis. FEBS J 2014; 281:2353-65. [DOI: 10.1111/febs.12787] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 02/17/2014] [Accepted: 03/18/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Min-Hsi Chiu
- Institute of Basic Medical Sciences; National Cheng Kung University; Tainan Taiwan
| | - Hsiao-Sheng Liu
- Department of Microbiology and Immunology; National Cheng Kung University; Tainan Taiwan
| | - Yi-Hui Wu
- Department of Obstetrics and Gynecology; College of Medicine; National Cheng Kung University and Hospital; Tainan Taiwan
| | - Meng-Ru Shen
- Department of Obstetrics and Gynecology; College of Medicine; National Cheng Kung University and Hospital; Tainan Taiwan
- Department of Pharmacology; National Cheng Kung University; Tainan Taiwan
| | - Cheng-Yang Chou
- Department of Obstetrics and Gynecology; College of Medicine; National Cheng Kung University and Hospital; Tainan Taiwan
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Shmukler BE, Hsu A, Alves J, Trudel M, Rust MB, Hubner CA, Rivera A, Alper SL. N-ethylmaleimide activates a Cl(-)-independent component of K(+) flux in mouse erythrocytes. Blood Cells Mol Dis 2013; 51:9-16. [PMID: 23481459 PMCID: PMC3646938 DOI: 10.1016/j.bcmd.2013.02.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 02/04/2013] [Indexed: 11/17/2022]
Abstract
The K-Cl cotransporters (KCCs) of mouse erythrocytes exhibit higher basal activity than those of human erythrocytes, but are similarly activated by cell swelling, by hypertonic urea, and by staurosporine. However, the dramatic stimulation of human erythroid KCCs by N-ethylmaleimide (NEM) is obscured in mouse erythrocytes by a prominent NEM-stimulated K(+) efflux that lacks Cl(-)-dependence. The NEM-sensitivity of Cl(-)-independent K(+) efflux of mouse erythrocytes is lower than that of KCC. The genetically engineered absence of the K-Cl cotransporters KCC3 and KCC1 from mouse erythrocytes does not modify Cl(-)-independent K(+) efflux. Mouse erythrocytes genetically devoid of the Gardos channel KCNN4 show increased NEM-sensitivity of both Cl(-)-independent K(+) efflux and K-Cl cotransport. The increased NEM-sensitivity and stimulation magnitude of Cl(-)-independent K(+) efflux in mouse erythrocytes expressing transgenic hypersickling human hemoglobin SAD (HbSAD) are independent of the presence of KCC3 and KCC1, but absence of KCNN4 reduces the stimulatory effect of HbSAD. NEM-stimulated Cl(-)-independent K(+) efflux of mouse red cells is insensitive to ouabain and bumetanide, but partially inhibited by chloroquine, barium, and amiloride. The NEM-stimulated activity is modestly reduced at pH6.0 but not significantly altered at pH8.0, and is abolished at 0°C. Although the molecular identity of this little-studied K(+) efflux pathway of mouse erythrocytes remains unknown, its potential role in the pathophysiology of sickle red cell dehydration will be important for the extrapolation of studies in mouse models of sickle cell disease to our understanding of humans with sickle cell anemia.
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Affiliation(s)
- Boris E. Shmukler
- Divisions of Nephrology and Molecular and Vascular Medicine, Beth Israel Deaconess Medical Center, Boston, MA
| | - Ann Hsu
- Divisions of Nephrology and Molecular and Vascular Medicine, Beth Israel Deaconess Medical Center, Boston, MA
| | - Jessica Alves
- Department of Laboratory Medicine, Children’s Hospital, Boston, MA
| | - Marie Trudel
- Institut de Recherches Cliniques de Montréal, Molecular Genetics and Development, Faculte de Medecine, University of Montreal, Montreal
| | - Marco B. Rust
- Neurobiology/Neurophysiology Group, University of Kaiserslautern, Kaiserslautern, Germany
| | | | - Alicia Rivera
- Department of Laboratory Medicine, Children’s Hospital, Boston, MA
- Department of Pathology, Harvard Medical School, Boston, MA
| | - Seth L. Alper
- Divisions of Nephrology and Molecular and Vascular Medicine, Beth Israel Deaconess Medical Center, Boston, MA
- Department of Medicine, Harvard Medical School, Boston, MA
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Salin-Cantegrel A, Shekarabi M, Rasheed S, Charron FM, Laganière J, Gaudet R, Dion PA, Lapointe JY, Rouleau GA. Potassium-chloride cotransporter 3 interacts with Vav2 to synchronize the cell volume decrease response with cell protrusion dynamics. PLoS One 2013; 8:e65294. [PMID: 23724134 PMCID: PMC3665532 DOI: 10.1371/journal.pone.0065294] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Accepted: 04/29/2013] [Indexed: 12/01/2022] Open
Abstract
Loss-of-function of the potassium-chloride cotransporter 3 (KCC3) causes hereditary motor and sensory neuropathy with agenesis of the corpus callosum (HMSN/ACC), a severe neurodegenerative disease associated with defective midline crossing of commissural axons in the brain. Conversely, KCC3 over-expression in breast, ovarian and cervical cancer is associated with enhanced tumor cell malignancy and invasiveness. We identified a highly conserved proline-rich sequence within the C-terminus of the cotransporter which when mutated leads to loss of the KCC3-dependent regulatory volume decrease (RVD) response in Xenopus Laevis oocytes. Using SH3 domain arrays, we found that this poly-proline motif is a binding site for SH3-domain containing proteins in vitro. This approach identified the guanine nucleotide exchange factor (GEF) Vav2 as a candidate partner for KCC3. KCC3/Vav2 physical interaction was confirmed using GST-pull down assays and immuno-based experiments. In cultured cervical cancer cells, KCC3 co-localized with the active form of Vav2 in swelling-induced actin-rich protruding sites and within lamellipodia of spreading and migrating cells. These data provide evidence of a molecular and functional link between the potassium-chloride co-transporters and the Rho GTPase-dependent actin remodeling machinery in RVD, cell spreading and cell protrusion dynamics, thus providing new insights into KCC3's involvement in cancer cell malignancy and in corpus callosum agenesis in HMSN/ACC.
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Affiliation(s)
- Adèle Salin-Cantegrel
- Centre of Excellence in Neuroscience of University of Montreal, Montréal, Québec, Canada
- Centre Hospitalier de l′Université de Montréal Research Centre, Montréal, Québec, Canada
| | - Masoud Shekarabi
- Centre of Excellence in Neuroscience of University of Montreal, Montréal, Québec, Canada
- Centre Hospitalier de l′Université de Montréal Research Centre, Montréal, Québec, Canada
| | - Sarah Rasheed
- Centre of Excellence in Neuroscience of University of Montreal, Montréal, Québec, Canada
- Centre Hospitalier de l′Université de Montréal Research Centre, Montréal, Québec, Canada
| | | | - Janet Laganière
- Centre of Excellence in Neuroscience of University of Montreal, Montréal, Québec, Canada
- Centre Hospitalier de l′Université de Montréal Research Centre, Montréal, Québec, Canada
| | - Rebecca Gaudet
- Centre of Excellence in Neuroscience of University of Montreal, Montréal, Québec, Canada
- Centre Hospitalier de l′Université de Montréal Research Centre, Montréal, Québec, Canada
| | - Patrick A. Dion
- Centre of Excellence in Neuroscience of University of Montreal, Montréal, Québec, Canada
- Centre Hospitalier de l′Université de Montréal Research Centre, Montréal, Québec, Canada
- Department of Pathology and Cell Biology, Université de Montréal, Montréal, Québec, Canada
| | | | - Guy A. Rouleau
- Centre of Excellence in Neuroscience of University of Montreal, Montréal, Québec, Canada
- Centre Hospitalier de l′Université de Montréal Research Centre, Montréal, Québec, Canada
- Montreal Neurological Institute, McGill University, Montréal, Québec, Canada
- * E-mail:
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Affiliation(s)
- Anselm A Zdebik
- UCL Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
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Sun YT, Shieh CC, Delpire E, Shen MR. K⁺-Cl⁻ cotransport mediates the bactericidal activity of neutrophils by regulating NADPH oxidase activation. J Physiol 2012; 590:3231-43. [PMID: 22526882 DOI: 10.1113/jphysiol.2011.225300] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Neutrophilic phagocytosis is an essential component of innate immunity. During phagocytosis, the generation of bactericidal hypochlorous acid(HOCl) requires the substrates, Cl− and superoxide produced by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase to kill the internalized pathogens. Here we show that the neutrophilic K+–Cl− cotransporter (KCC) constitutes aCl− permeation pathway and mediates the bactericidal activity by regulating NADPH oxidase activation. Dihydroindenyloxy alkanoic acid (DIOA), a KCC inhibitor, suppressed the toxin- or chemical-induced efflux of 36Cl− or 86Rb+, and diminished the production of superoxide in human and murine neutrophils. Inhibition of KCC activity or knockdown of KCC expression, in particular KCC3, reduced the phosphorylation as well as the membrane recruitment of oxidase components. Activated neutrophils displayed a significant colocalization of KCC3 and early endosomal marker, indicating that KCC3 could be localized on the phagosomes once neutrophils are activated. The NADPH oxidase activity and the phosphorylation level of oxidase component were 50% lower in the neutrophils isolated from KCC3−/− mice than in the neutrophils isolated from KCC3+/+ mice.Mortality rate after intraperitoneal challenge with Staphylococcus aureus was higher in KCC3−/− mice, and the bacterial clearance was impaired in the survivors.We conclude that, in activated neutrophil, NADPH oxidase complexes are associated with KCC3 at the plasma membrane and are internalized to form phagosomes, where KCC activity and expression level affect the production of oxidants.
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Affiliation(s)
- Yuan-Ting Sun
- Institute of Clinical Medicine, National Cheng Kung University Hospital, Tainan 704, Taiwan
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27
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Lee MY, Shen MR. Epithelial-mesenchymal transition in cervical carcinoma. Am J Transl Res 2012; 4:1-13. [PMID: 22347518 PMCID: PMC3276374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Accepted: 12/23/2011] [Indexed: 05/31/2023]
Abstract
During the progression of epithelial cancer, cells usually lose epithelial characteristic features and gain a mesenchymal phenotype. Cervical cancer is a common female malignancy worldwide. Despite the generally good prognosis for early-stage cervical cancer patients, many patients still die as a result of metastasis and recurrence. Epithelial-mesenchymal transition (EMT) has been implicated in the metastasis of primary tumors and provides molecular mechanisms for cervical cancer metastasis. Here we provide an up-to-date overview regarding the program of EMT in cervical cancer. In the stepwise progression of cervical cancer, human papilloma viral proteins contribute to the cell transformation and the conversion of typical epithelial cells to the epithelial carcinoma cells with hybrid epithelial and mesenchymal characteristics. Molecules related to the EMT program of cervical cancer cells are summarized in this review paper. Several soluble factors acting on their cognate receptors stimulate the mesenchymal transition of cervical epithelial cells. Ion transport system as well as cytoskeletal modulators also stimulate the progression of EMT program in cervical carcinoma cells. Transcriptional factors such as Snail, Twist1, Twist2, and six1 homeoproteins are involved in the complicated regulation and cervical cancer metastasis. Among the various signalings associated with EMT program, Snail is a central transcription factor which governs EMT program. In contrast to tumor promoters, several tumor suppressors such as SFRP1/2 and LMX-1A have been reported to suppress tumorigenesis as well as metastatic spread through inhibiting the EMT program.
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Affiliation(s)
- Mei-Yi Lee
- Department of PharmacologyCollege of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Infectious Disease and Signaling Research CenterCollege of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
| | - Meng-Ru Shen
- Department of PharmacologyCollege of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Infectious Disease and Signaling Research CenterCollege of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Department of Obstetrics & GynecologyCollege of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Advanced Optoelectronic Technology CenterCollege of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
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Wei WC, Akerman CJ, Newey SE, Pan J, Clinch NWV, Jacob Y, Shen MR, Wilkins RJ, Ellory JC. The potassium-chloride cotransporter 2 promotes cervical cancer cell migration and invasion by an ion transport-independent mechanism. J Physiol 2011; 589:5349-59. [PMID: 21911617 PMCID: PMC3240877 DOI: 10.1113/jphysiol.2011.214635] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 09/09/2011] [Indexed: 01/24/2023] Open
Abstract
K(+)-Cl(-) cotransporters (KCCs) play a fundamental role in epithelial cell function, both in the context of ionic homeostasis and also in cell morphology, cell division and locomotion. Unlike other ubiquitously expressed KCC isoforms, expression of KCC2 is widely considered to be restricted to neurons, where it is responsible for maintaining a low intracellular chloride concentration to drive hyperpolarising postsynaptic responses to the inhibitory neurotransmitters GABA and glycine. Here we report a novel finding that KCC2 is widely expressed in several human cancer cell lines including the cervical cancer cell line (SiHa). Membrane biotinylation assays and immunostaining showed that endogenous KCC2 is located on the cell membrane of SiHa cells. To elucidate the role of KCC2 in cervical tumuorigenesis, SiHa cells with stable overexpression or knockdown of KCC2 were employed. Overexpression of KCC2 had no significant effect on cell proliferation but dramatically suppressed cell spreading and stress fibre organization, while knockdown of KCC2 showed opposite effects. In addition, insulin-like growth factor 1 (IGF-1)-induced cell migration and invasiveness were significantly increased by overexpression of KCC2. KCC2-induced cell migration and invasion were not dependent on KCC2 transport function since overexpression of an activity-deficient mutant KCC2 still increased IGF-1-induced cell migration and invasion. Moreover, overexpression of KCC2 significantly diminished the number of focal adhesions, while knockdown of KCC2 increased their number. Taken together, our data establish that KCC2 expression and function are not restricted to neurons and that KCC2 serves to increase cervical tumourigenesis via an ion transport-independent mechanism.
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Affiliation(s)
- Wei-Chun Wei
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
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29
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Chen YF, Chou CY, Ellory JC, Shen MR. The emerging role of KCl cotransport in tumor biology. Am J Transl Res 2010; 2:345-355. [PMID: 20733945 PMCID: PMC2923859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 06/12/2010] [Indexed: 05/29/2023]
Abstract
The electroneutral KCl cotransport carried out by the KCl cotransporter family (KCC) plays a significant role in the ionic and osmotic homeostasis of epithelial cells. Here we review the emerging importance of KCl cotransport in epithelial carcinogenesis and tumor malignant behaviors. The malignant transformation of cervical epithelial cells is associated with the differential expression of volume-sensitive KCC isoforms. The loss-of-function KCC mutant cervical cancer cells exhibit inhibited cell growth accompanied by decreased activities of the cell cycle regulators and matrix metalloproteinase. Additionally, insulin-like growth factor-1 (IGF-1) stimulation of KCl cotransport plays an important role in IGF-1 signaling to promote growth and spread of gynecological cancers. IGF-1 upregulates KCC3 and KCC4 which are differentially required for cancer cell proliferation and invasiveness. KCC3 overexpression downregu-lates E-cadherin/beta-catenin complex formation by inhibiting the transcription of E-cadherin gene and accelerating the proteosome-dependent degradation of beta-catenin protein. That therefore promotes the epithelial-mesenchymal transition of cervical cancer cells, and thereby stimulating tumor progression. Moreover, epidermal-growth factor (EGF) and IGF-1 stimulate the membrane recruitment of KCC4 at lamellipodia through myosin Va-actin trafficking route. KCC4 functions as a membrane scaffold forthe assembly of signal complexes via the association with the actin-binding protein, ezrin. The molecular studies of surgical specimens suggest that the expression of KCC3, KCC4, and their stimulators, EGF or IGF-1, exhibit a close association with the clinical outcome of cancer patients. Therefore, KCC3, KCC4, EGF, and IGF-1 may be a panel of biomarkers to predict cancer patient outcome.
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Affiliation(s)
- Yih-Fung Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung UniversityTainan 704, Taiwan
- Department of Pharmacology, College of Medicine, National Cheng Kung UniversityTainan 704, Taiwan
| | - Cheng-Yang Chou
- Department of Obstetrics & Gynecology, College of Medicine, National Cheng Kung UniversityTainan 704, Taiwan
| | - J Clive Ellory
- Department of Physiology, Anatomy and Genetics, University of OxfordOxford, OX13PT, UK
| | - Meng-Ru Shen
- Department of Pharmacology, College of Medicine, National Cheng Kung UniversityTainan 704, Taiwan
- Department of Obstetrics & Gynecology, College of Medicine, National Cheng Kung UniversityTainan 704, Taiwan
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Zhang D, Gopalakrishnan SM, Freiberg G, Surowy CS. A thallium transport FLIPR-based assay for the identification of KCC2-positive modulators. JOURNAL OF BIOMOLECULAR SCREENING 2010; 15:177-84. [PMID: 20086212 DOI: 10.1177/1087057109355708] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
KCC2, potassium chloride cotransporter 2, is expressed exclusively in the CNS (on inhibitory neurons) and plays a major role in maintaining appropriately low intracellular chloride levels that ensure inhibitory actions of GABA(A) and glycine receptors. As such, it plays a pivotal role in inhibitory mechanisms that control neuronal excitation in the CNS. KCC2 downregulation has been implicated in various excitatory disorders, such as epilepsy and neuropathic pain. Positive modulators of KCC2 expression or activity may thus provide effective therapy for these disorders. However, the identification of such agents is hindered by the lack of a high-throughput screening method. Here the authors report the development of a fluorescence-based thallium (Tl(+)) transport assay using a Fluorometric Imaging Plate Reader (FLIPR), in which KCC2 activity is assessed by measuring the initial rate of KCC2-mediated Tl(+) transport/influx. The authors demonstrate Tl(+)/Cl(-) cotransport by KCC2, which exhibits a high apparent affinity for Tl(+) and dependency on the presence of the Cl(-) ion. Pharmacological studies revealed anticipated effects and potencies of known KCC-positive (NEM, staurosporine) and KCC-negative (DIOA, furosemide) modulators. The authors demonstrate that the assay is robust and reproducible and can be employed in high-throughput screening for positive modulators of KCC2 as potential therapeutic agents.
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Affiliation(s)
- Di Zhang
- Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA.
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Mahato M, Pal P, Kamilya T, Sarkar R, Chaudhuri A, Talapatra GB. Influence of KCl on the interfacial activity and conformation of hemoglobin studied by Langmuir–Blodgett technique. Phys Chem Chem Phys 2010; 12:12997-3006. [DOI: 10.1039/c0cp00344a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Chen YF, Chou CY, Wilkins RJ, Ellory JC, Mount DB, Shen MR. Motor protein-dependent membrane trafficking of KCl cotransporter-4 is important for cancer cell invasion. Cancer Res 2009; 69:8585-93. [PMID: 19887603 DOI: 10.1158/0008-5472.can-09-2284] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The KCl cotransporter (KCC) is a major determinant of osmotic homeostasis and plays an emerging role in tumor biology. This study stresses the important role of KCC4 in tumor malignant behavior. Real-time reverse transcription-PCR on samples collected by laser microdissection and immunofluorescent stainings with different KCC isoform antibodies indicate that KCC4 is abundant in metastatic cervical and ovarian cancer tissues. Insulin-like growth factor I (IGF-I) and epidermal growth factor (EGF) stimulate KCC4 recruitment from a presumably inactive cytoplasmic pool of endoplasmic reticulum and Golgi to plasma membrane along actin cytoskeleton that is significantly inhibited by LY294002 and wortmannin. Throughout the trafficking process, KCC4 is incorporated into lipid rafts that function as a platform for the association between KCC4 and myosin Va, an actin-dependent motor protein. KCC4 and ezrin, a membrane cytoskeleton linker, colocalize at lamellipodia of migratory cancer cells. Interference with KCC activity by either an inhibitor or a dominant-negative loss-of-function mutant profoundly suppressed the IGF-I-induced membrane trafficking of KCC4 and the structural interaction between KCC4 and ezrin near the cell surface. Endogenous cancer cell invasiveness was significantly attenuated by small interfering RNA targeting KCC4, and the residual invasiveness was much less sensitive to IGF-I or EGF stimulation. In the metastatic cancer tissues, KCC4 colocalizes with IGF-I or EGF, indicating a likely in vivo stimulation of KCC4 function by growth factors. Thus, blockade of KCC4 trafficking and surface expression may provide a potential target for the prevention of IGF-I- or EGF-dependent cancer spread.
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Affiliation(s)
- Yih-Fung Chen
- Department of Pharmacology, College of Medicine, Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan
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Kovacs P, Hajnal A. In vivo electrophysiological effects of insulin in the rat brain. Neuropeptides 2009; 43:283-93. [PMID: 19541365 PMCID: PMC2759775 DOI: 10.1016/j.npep.2009.05.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Revised: 05/25/2009] [Accepted: 05/25/2009] [Indexed: 12/17/2022]
Abstract
Brain insulin has widespread metabolic, neurotrophic, and neuromodulatory functions and is involved in the central regulation of food intake and body weight, learning and memory, neuronal development, neuronal apoptosis, and aging. To understand the neuromodulatory role of insulin, we aimed to characterize its yet undefined in vivo electrophysiological effects. We elected to record from the cerebellar cortex because this region has average insulin concentration and insulin receptor content in relation to the whole brain, and has been previously shown to be a target for insulin signaling. We used in vivo microiontophoresis to apply insulin juxtaneuronally while simultaneously recording changes in spontaneous neuronal activity. The analysis included 553 significant neuronal responses to insulin and other related agents recorded from 47 cerebellar neurons of the rat. We found that (1) insulin stimulation produced instant and reversible electrophysiological effects on all of the recorded neurons, and that (2) these effects were mostly dependent on prior or simultaneous GABA application (94-96%). Specifically, (a) inhibitory responses to insulin were the most common (58-62%), and were dose-dependent with respect to GABA pretreatments and blocked by co-administration of the insulin receptor inhibitor HNMPA. (b) In the second largest set of neurons (32-38%) insulin decreased the magnitude of GABA inhibitions when co-applied. (c) In contrast, only a small number of neurons showed GABA-independent responses to insulin application (4-6%), which were exclusively neuronal excitations. The present findings demonstrate that insulin has direct electrophysiological effects on central neurons in vivo and these effects are highly influenced by GABA-ergic inputs.
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Affiliation(s)
- Peter Kovacs
- Department of Neural and Behavioral Sciences, Pennsylvania State University, The Milton S. Hershey Medical Center, 500 University Drive, Hershey, PA 17033, USA.
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Lambert IH, Klausen TK, Bergdahl A, Hougaard C, Hoffmann EK. ROS activate KCl cotransport in nonadherent Ehrlich ascites cells but K+ and Cl- channels in adherent Ehrlich Lettré and NIH3T3 cells. Am J Physiol Cell Physiol 2009; 297:C198-206. [PMID: 19419998 DOI: 10.1152/ajpcell.00613.2008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Addition of H(2)O(2) (0.5 mM) to Ehrlich ascites tumor cells under isotonic conditions results in a substantial (22 +/- 1%) reduction in cell volume within 25 min. The cell shrinkage is paralleled by net loss of K(+), which was significant within 8 min, whereas no concomitant increase in the K(+) or Cl(-) conductances could be observed. The H(2)O(2)-induced cell shrinkage was unaffected by the presence of clofilium and clotrimazole, which blocks volume-sensitive and Ca(2+)-activated K(+) channels, respectively, and is unaffected by a raise in extracellular K(+) concentration to a value that eliminates the electrochemical driving force for K(+). On the other hand, the H(2)O(2)-induced cell shrinkage was impaired in the presence of the KCl cotransport inhibitor (dihydro-indenyl)oxyalkanoic acid (DIOA), following substitution of NO(3)(-) for Cl(-), and when the driving force for KCl cotransport was omitted. It is suggested that H(2)O(2) activates electroneutral KCl cotransport in Ehrlich ascites tumor cells and not K(+) and Cl(-) channels. Addition of H(2)O(2) to hypotonically exposed cells accelerates the regulatory volume decrease and the concomitant net loss of K(+), whereas no additional increase in the K(+) and Cl(-) conductance was observed. The effect of H(2)O(2) on cell volume was blocked by the serine-threonine phosphatase inhibitor calyculin A, indicating an important role of serine-threonine phosphorylation in the H(2)O(2)-mediated activation of KCl cotransport in Ehrlich cells. In contrast, addition of H(2)O(2) to adherent cells, e.g., Ehrlich Lettré ascites cells, a subtype of the Ehrlich ascites tumor cells, and NIH3T3 mouse fibroblasts increased the K(+) and Cl(-) conductances after hypotonic cell swelling. Hence, H(2)O(2) induces KCl cotransport or K(+) and Cl(-) channels in nonadherent and adherent cells, respectively.
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Affiliation(s)
- Ian Henry Lambert
- Dept. of Biology, The August Krogh Building, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark.
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35
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Regulation of lens volume: Implications for lens transparency. Exp Eye Res 2009; 88:144-50. [DOI: 10.1016/j.exer.2008.05.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Revised: 05/20/2008] [Accepted: 05/20/2008] [Indexed: 11/23/2022]
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Maki M, Miyazaki H, Niisato N, Morihara T, Marunaka Y, Kubo T. Blockers of K+/Cl- transporter/channels diminish proliferation of osteoblastic cells. Biomed Res 2009; 30:137-40. [DOI: 10.2220/biomedres.30.137] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Functional analysis of a potassium-chloride co-transporter 3 (SLC12A6) promoter polymorphism leading to an additional DNA methylation site. Neuropsychopharmacology 2009; 34:458-67. [PMID: 18536702 DOI: 10.1038/npp.2008.77] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The human potassium-chloride co-transporter 3 (KCC3, SLC12A6) is involved in cell proliferation and in electro-neutral movement of ions across the cell membrane. The gene (SLC12A6) is located on chromosome 15q14, a region that has previously shown linkage with bipolar disorder, schizophrenia, rolandic epilepsy, idiopathic generalized epilepsy, autism and attention deficit/hyperactivity disorder. Furthermore, recessively inherited mutations of SLC12A6 cause Andermann syndrome, characterized by agenesis of the corpus callosum, which is associated with peripheral neuropathy and psychoses. Recently, we have demonstrated the association of two G/A promoter polymorphisms of SLC12A6 with bipolar disorder in a case-control study, and familial segregation of the rare variants as well as a trend toward association with schizophrenia. To investigate functional consequences of these polymorphisms, lymphocyte DNA was extracted, bisulfite modified, and subsequently sequenced. To investigate SLC12A6 promoter activity, various promoter constructs were generated and analyzed by luciferase reporter gene assays. We provide evidence that the G- allele showed a significant reduction of reporter gene expression. In human lymphocytes, the allele harboring the rare upstream G nucleotide was found to be methylated at the adjacent C position, possibly accountable for tissue-specific reduction in gene expression in vivo. Here we demonstrate functionality of an SNP associated with psychiatric disease and our results may represent a functional link between genetic variation and an epigenetic modification.
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Jiao Y, Jin X, Yan J, Zhang C, Jiao F, Li X, Roe BA, Mount DB, Gu W. A deletion mutation in Slc12a6 is associated with neuromuscular disease in gaxp mice. Genomics 2008; 91:407-14. [PMID: 18343091 DOI: 10.1016/j.ygeno.2007.12.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Revised: 12/17/2007] [Accepted: 12/31/2007] [Indexed: 11/17/2022]
Abstract
Giant axonopathy (gaxp), an autosomal recessive mouse mutation, exhibits ataxia of the hind legs with a slight side-to-side wobble while walking. Within the genomic region of the gaxp locus, a total of 94 transcripts were identified; the annotation of these genes using OMIM and PubMed yielded three potential candidate genes. By cDNA microarray analysis, 54 genes located on or near the gaxp locus were found to exhibit differential expression between gaxp and littermate controls. Based on microarray data and the known function of genes identified, Slc12a6 was selected as the primary candidate gene and analyzed using the Reveal technology of SpectruMedix. A 17-base deletion was detected from within exon 4 of Slc12a6. Reverse transcriptase polymerase chain reaction validated the difference in Slc12a6 expression in different types of mice at the mRNA level, revealing a marked reduction in gaxp mice. Western blot analysis indicated that the protein product of Slc12a6, the K(+)-Cl(-) cotransporter Kcc3, was not detectable in gaxp mice. The causative role of the exon 4 mutation within Slc12a6 in the gaxp phenotype was further confirmed by screening multiple inbred strains and by excluding the mutation of nearby genes within the gaxp locus.
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Affiliation(s)
- Yan Jiao
- Department of Orthopaedic Surgery (Campbell Clinic), University of Tennessee Health Science Center, Memphis, TN 38163, USA
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Miyazaki H, Shiozaki A, Niisato N, Ohsawa R, Itoi H, Ueda Y, Otsuji E, Yamagishi H, Iwasaki Y, Nakano T, Nakahari T, Marunaka Y. Chloride ions control the G1/S cell-cycle checkpoint by regulating the expression of p21 through a p53-independent pathway in human gastric cancer cells. Biochem Biophys Res Commun 2007; 366:506-12. [PMID: 18067855 DOI: 10.1016/j.bbrc.2007.11.144] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Accepted: 11/29/2007] [Indexed: 12/11/2022]
Abstract
The aim of the present study is to investigate whether the chloride affects cell growth and cell-cycle progression of cancer cells. In human gastric cancer MKN28 cells, the culture in the Cl(-)-replaced medium (replacement of Cl(-) by NO(3)(-)) decreased the intracellular chloride concentration ([Cl(-)](i)) and inhibited cell growth. The inhibition of cell growth was due to cell-cycle arrest at the G(0)/G(1) phase caused by diminution of CDK2 and phosphorylated Rb. The culture of cells in the Cl(-)-replaced medium significantly increased expressions of p21 mRNA and protein without any effects on p53. These observations indicate that chloride ions play important roles in cell-cycle progression by regulating the expression of p21 through a p53-independent pathway in human gastric cancer cells, leading to a novel, unique therapeutic strategy for gastric cancer treatment via control of [Cl(-)](i).
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Affiliation(s)
- Hiroaki Miyazaki
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
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KCl Cotransporter-3 Down-regulates E-Cadherin/β-Catenin Complex to Promote Epithelial-Mesenchymal Transition. Cancer Res 2007; 67:11064-73. [DOI: 10.1158/0008-5472.can-07-2443] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Capó-Aponte JE, Iserovich P, Reinach PS. Characterization of regulatory volume behavior by fluorescence quenching in human corneal epithelial cells. J Membr Biol 2007; 207:11-22. [PMID: 16463139 DOI: 10.1007/s00232-005-0800-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Revised: 10/01/2005] [Indexed: 10/25/2022]
Abstract
An in-depth understanding of the mechanisms underlying regulatory volume behavior in corneal epithelial cells has been in part hampered by the lack of adequate methodology for characterizing this phenomenon. Accordingly, we developed a novel approach to characterize time-dependent changes in relative cell volume induced by anisosmotic challenges in calcein-loaded SV40-immortalized human corneal epithelial (HCE) cells with a fluorescence microplate analyzer. During a hypertonic challenge, cells shrank rapidly, followed by a temperature-dependent regulatory volume increase (RVI), tau(c) = 19 min. In contrast, a hypotonic challenge induced a rapid (tau(c) = 2.5 min) regulatory volume decrease (RVD). Temperature decline from 37 to 24 degrees C reduced RVI by 59%, but did not affect RVD. Bumetanide (50 microM), ouabain (1 mM), DIDS (1 mM), EIPA (100 microM), or Na(+)-free solution reduced the RVI by 60, 61, 39, 32, and 69%, respectively. K+, Cl- channel and K(+)-Cl(-) cotransporter (KCC) inhibition obtained with either 4-AP (1 mM), DIDS (1 mM), DIOA (100 microM), high K+ (20 mM) or Cl(-)-free solution, suppressed RVD by 42, 47, 34, 52 and 58%, respectively. KCC activity also affects steady-state cell volume, since its inhibition or stimulation induced relative volume alterations under isotonic conditions. Taken together, K+ and Cl- channels in parallel with KCC activity are important mediators of RVD, whereas RVI is temperature-dependent and is essentially mediated by the Na(+)-K(+)-2Cl(-) cotransporter (Na(+)-K(+)-2Cl(-)) and the Na(+)-K(+) pump. Inhibition of K+ and Cl- channels and KCC but not Na(+)-K(+)-2Cl(-) affect steady-state cell volume under isotonic conditions. This is the first report that KCC activity is required for HCE cell volume regulation and maintenance of steady-state cell volume.
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Affiliation(s)
- J E Capó-Aponte
- Department of Biological Sciences, College of Optometry, State University of New York, New York, NY 10036, USA
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Byun N, Delpire E. Axonal and periaxonal swelling precede peripheral neurodegeneration in KCC3 knockout mice. Neurobiol Dis 2007; 28:39-51. [PMID: 17659877 PMCID: PMC2242858 DOI: 10.1016/j.nbd.2007.06.014] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 05/27/2007] [Accepted: 06/08/2007] [Indexed: 01/01/2023] Open
Abstract
We have previously reported CNS and locomotor deficits in KCC3 knockout mice, an animal model of agenesis of the corpus callosum associated with peripheral neuropathy (ACCPN) [Howard, H.C., Mount, D.B., Rochefort, D., Byun, N., Dupre, N., Lu, J., Fan, X., Song, L., Riviere, J.B., Prevost, C., Horst, J., Simonati, A., Lemcke, B., Welch, R., England, R., Zhan, F.Q., Mercado, A., Siesser, W.B., George, A.L., Jr., McDonald, M.P., Bouchard, J.P., Mathieu, J., Delpire, E., Rouleau, G.A., 2002. The K-Cl cotransporter KCC3 is mutant in a severe peripheral neuropathy associated with agenesis of the corpus callosum. Nat. Genet. 32, 384-392]. To assess the role of KCC3 in peripheral axon and/or myelin development and maintenance, we determined its expression and performed a detailed morphometric analysis of sciatic nerves. Sciatic nerves of juvenile wild-type mice, but not of adult, express KCC3. In the knockout, Schwann cell/myelin development appears normal at P3, but axons are swollen. At P8 and into P30, some fibers accumulate fluid periaxonally. These initial swelling pathologies are followed by axon and myelin degeneration in adult nerves, leading to reduction in nerve conduction velocity. Mutant mice also exhibit decreased sensitivity to noxious pain. This evidence for fluid-related axonopathy, which ultimately result in neurodegeneration, implicates cell volume regulation as a critical component of peripheral nerve maintenance.
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Affiliation(s)
- Nellie Byun
- Neuroscience Graduate Program, Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, T-4202 MCN 1161 21st Avenue South, Nasvhille, TN 37232-2520, USA
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Capó-Aponte JE, Wang Z, Bildin VN, Iserovich P, Pan Z, Zhang F, Pokorny KS, Reinach PS. Functional and molecular characterization of multiple K-Cl cotransporter isoforms in corneal epithelial cells. Exp Eye Res 2007; 84:1090-103. [PMID: 17418819 PMCID: PMC2696115 DOI: 10.1016/j.exer.2007.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Revised: 12/19/2006] [Accepted: 02/06/2007] [Indexed: 11/20/2022]
Abstract
The dependence of regulatory volume decrease (RVD) activity on potassium-chloride cotransporter (KCC) isoform expression was characterized in corneal epithelial cells (CEC). During exposure to a 50% hypotonic challenge, the RVD response was larger in SV40-immortalized human CEC (HCEC) than in SV40-immortalized rabbit CEC (RCEC). A KCC inhibitor-[(dihydroindenyl)oxy] alkanoic acid (DIOA)-blocked RVD more in HCEC than RCEC. Under isotonic conditions, N-ethylmaleimide (NEM) produced KCC activation and transient cell shrinkage. Both of these changes were greater in HCEC than in RCEC. Immunoblot analysis of HCEC, RCEC, primary human CEC (pHCEC), and primary bovine CEC (BCEC) plasma membrane enriched fractions revealed KCC1, KCC3, and KCC4 isoform expression, whereas KCC2 was undetectable. During a hypotonic challenge, KCC1 membrane content increased more rapidly in HCEC than in RCEC. Such a challenge induced a larger increase and more transient p44/42MAPK activation in HCEC than RCEC. On the other hand, HCEC and RCEC p38MAPK phosphorylation reached peak activations at 2.5 and 15 min, respectively. Only in HCEC, pharmacological manipulation of KCC activity modified the hypotonicity-induced activation of p44/42MAPK, whereas p38MAPK phosphorylation was insensitive to such procedures in both cell lines. Larger increases in HCEC KCC1 membrane protein content correlated with their ability to undergo faster and more complete RVD. Furthermore, pharmacological activation of KCC increased p44/42MAPK phosphorylation in HCEC but not in RCEC, presumably a reflection of low KCC1 membrane expression in RCEC. These findings suggest that KCC1 plays a role in (i) maintaining isotonic steady-state cell volume homeostasis, (ii) recovery of isotonic cell volume after a hypotonic challenge through RVD, and (iii) regulating hypotonicity-induced activation of the p44/42MAPK signaling pathway required for cell proliferation.
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Affiliation(s)
- José E. Capó-Aponte
- Department of Biological Sciences, State University of New York, State College of Optometry, New York, NY 10036, USA
| | - Zheng Wang
- Department of Biological Sciences, State University of New York, State College of Optometry, New York, NY 10036, USA
| | - Victor N. Bildin
- Department of Biological Sciences, State University of New York, State College of Optometry, New York, NY 10036, USA
| | - Pavel Iserovich
- Department of Ophthalmology, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA
| | - Zan Pan
- Department of Biological Sciences, State University of New York, State College of Optometry, New York, NY 10036, USA
| | - Fan Zhang
- Department of Biological Sciences, State University of New York, State College of Optometry, New York, NY 10036, USA
| | - Kathryn S. Pokorny
- The Institute of Ophthalmology & Visual Science, New Jersey Medical School, University of Medicine & Dentistry, Newark, NJ 07101, USA
| | - Peter S. Reinach
- Department of Biological Sciences, State University of New York, State College of Optometry, New York, NY 10036, USA
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Colmenero-Flores JM, Martínez G, Gamba G, Vázquez N, Iglesias DJ, Brumós J, Talón M. Identification and functional characterization of cation-chloride cotransporters in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 50:278-92. [PMID: 17355435 DOI: 10.1111/j.1365-313x.2007.03048.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Chloride (Cl(-)) is an essential nutrient and one of the most abundant inorganic anions in plant tissues. We have cloned an Arabidopsis thaliana cDNA encoding for a member of the cation-Cl(-) cotransporter (CCC) family. Deduced plant CCC proteins are highly conserved, and phylogenetic analyses revealed their relationships to the sub-family of animal K(+):Cl(-) cotransporters. In Xenopus laevis oocytes, the A. thaliana CCC protein (At CCC) catalysed the co-ordinated symport of K(+), Na(+) and Cl(-), and this transport activity was inhibited by the 'loop' diuretic bumetanide, a specific inhibitor of vertebrate Na(+):K(+):Cl(-) cotransporters, indicating that At CCC encodes for a bona fide Na(+):K(+):Cl(-) cotransporter. Analysis of At CCC promoter-beta-glucuronidase transgenic Arabidopsis plants revealed preferential expression in the root and shoot vasculature at the xylem/symplast boundary, root tips, trichomes, leaf hydathodes, leaf stipules and anthers. Plants homozygous for two independent T-DNA insertions in the CCC gene exhibited shorter organs such as inflorescence stems, roots, leaves and siliques. The elongation zone of the inflorescence stem of ccc plants often necrosed during bolt emergence, while seed production was strongly impaired. In addition, ccc plants exhibited defective Cl(-) homeostasis under high salinity, as they accumulated higher and lower Cl(-) amounts in shoots and roots, respectively, than the treated wild type, suggesting At CCC involvement in long-distance Cl(-) transport. Compelling evidence is provided on the occurrence of cation-chloride cotransporters in the plant kingdom and their significant role in major plant developmental processes and Cl(-) homeostasis.
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Affiliation(s)
- José M Colmenero-Flores
- Centro de Genómica, Instituto Valenciano de Investigaciones Agrarias, Ctra. Moncada-Náquera Km. 5, 46113 Moncada, Valencia, Spain
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Hsu YM, Chou CY, Chen HHW, Lee WY, Chen YF, Lin PW, Alper SL, Ellory JC, Shen MR. IGF-1 upregulates electroneutral K-Cl cotransporter KCC3 and KCC4 which are differentially required for breast cancer cell proliferation and invasiveness. J Cell Physiol 2007; 210:626-36. [PMID: 17133354 DOI: 10.1002/jcp.20859] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The cellular function of electroneutral K-Cl cotransport (KCC) is to regulate epithelial ion transport and osmotic homeostasis. Here we investigate the mechanisms by which insulin-like growth factor 1 (IGF-1) cooperates with KCC to modulate breast cancer biology. IGF-1 stimulates KCC activity of MCF-7 breast cancer cells in a dose- and time-dependent manner. Increased KCC3 and KCC4 abundances contribute to IGF-1-enhanced KCC activity. Endogenous cellular invasiveness was modestly attenuated by KCC4-specific siRNA and the residual invasiveness was much less sensitive to IGF-1 stimulation. KCC3 knockdown significantly reduced basal growth rate and almost abolished IGF-1-stimulated cell proliferation. Consistently, MCF-7 cells obtained advantage in cell proliferation and invasiveness by overexpression of KCC3 and KCC4, respectively. Blockade of gene transcription by actinomycin D abolished IGF-1-mediated increase in KCC3 and KCC4 mRNA, indicating that IGF-1 increases KCC abundance through the regulation of KCC genes. IGF-1 treatment triggered phosphatidylinositol 3-kinase and mitogen-activated protein kinase (MAPK) cascades which were differentially required for IGF-1-stimulated biosynthesis of KCC3 and KCC4. Loss-of-function mutations in KCC significantly inhibited the development and progression of xenograft tumor in SCID mice. The expression level of IGF-1 and KCC polypeptides in the surgical specimens showed a good linear correlation, suggesting autocrine or paracrine IGF-1 stimulation of KCC production in vivo. Among patients with early-stage node-negative breast cancer, disease-free survival (DFS) and overall survival (OS) curves were significantly different based on IGF-1 and KCC expression. Thus, we conclude that KCC activation by IGF-1 plays an important role in IGF-1 receptor signaling to promote growth and spread of breast cancer cells.
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Affiliation(s)
- Yueh-Mei Hsu
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan
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Carter CJ. Multiple genes and factors associated with bipolar disorder converge on growth factor and stress activated kinase pathways controlling translation initiation: implications for oligodendrocyte viability. Neurochem Int 2007; 50:461-90. [PMID: 17239488 DOI: 10.1016/j.neuint.2006.11.009] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Accepted: 11/27/2006] [Indexed: 02/06/2023]
Abstract
Famine and viral infection, as well as interferon therapy have been reported to increase the risk of developing bipolar disorder. In addition, almost 100 polymorphic genes have been associated with this disease. Several form most of the components of a phosphatidyl-inositol signalling/AKT1 survival pathway (PIK3C3, PIP5K2A, PLCG1, SYNJ1, IMPA2, AKT1, GSK3B, TCF4) which is activated by growth factors (BDNF, NRG1) and also by NMDA receptors (GRIN1, GRIN2A, GRIN2B). Various other protein products of genes associated with bipolar disorder either bind to or are affected by phosphatidyl-inositol phosphate products of this pathway (ADBRK2, HIP1R, KCNQ2, RGS4, WFS1), are associated with its constituent elements (BCR, DUSP6, FAT, GNAZ) or are downstream targets of this signalling cascade (DPYSL2, DRD3, GAD1, G6PD, GCH1, KCNQ2, NOS3, SLC6A3, SLC6A4, SST, TH, TIMELESS). A further pathway relates to endoplasmic reticulum-stress (HSPA5, XBP1), caused by problems in protein glycosylation (ALG9), growth factor receptor sorting (PIK3C3, HIP1R, SYBL1), or aberrant calcium homoeostasis (WFS1). Key processes relating to these pathways appear to be under circadian control (ARNTL, CLOCK, PER3, TIMELESS). DISC1 can also be linked to many of these pathways. The growth factor pathway promotes protein synthesis, while the endoplasmic reticulum stress pathway, and other stress pathways activated by viruses and cytokines (IL1B, TNF, Interferons), oxidative stress or starvation, all factors associated with bipolar disorder risk, shuts down protein synthesis via control of the EIF2 alpha and beta translation initiation complex. For unknown reasons, oligodendrocytes appear to be particularly prone to defects in the translation initiation complex (EIF2B) and the convergence of these environmental and genomic signalling pathways on this area might well explain their vulnerability in bipolar disorder.
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Lauf PK, Adragna NC, Dupre N, Bouchard JP, Rouleau GA. K–Cl cotransport in red blood cells from patients with KCC3 isoform mutantsThis paper is one of a selection of papers published in this Special Issue, entitled CSBMCB — Membrane Proteins in Health and Disease. Biochem Cell Biol 2006; 84:1034-44. [PMID: 17215889 DOI: 10.1139/o06-203] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Red blood cells (RBCs) possess the K–Cl cotransport (KCC) isoforms 1, 3, and 4. Mutations within a given isoform may affect overall KCC activity. In a double-blind study, we analyzed, with Rb as a K congener, K fluxes (total flux, ouabain-sensitive Na+/K+ pump, and bumetanide-sensitive Na–K–2Cl cotransport, Cl-dependent, and ouabain- and bumetanide-insensitive KCC with or without stimulation by N-ethylmaleimide (NEM) and staurosporine or Mg removal, and basal channel-mediated fluxes, osmotic fragility, and ions and water in the RBCs of 8 controls, and of 8 patients with hereditary motor and sensory neuropathy with agenesis of corpus callosum (HMSN–ACC) with defined KCC3 mutations (813FsX813 and Phe529FsX532) involving the truncations of 338 and 619 C-terminal amino acids, respectively. Water and ion content and, with one exception, mean osmotic fragility, as well as K fluxes without stimulating agents, were similar in controls and HMSN–ACC RBCs. However, the NEM-stimulated KCC was reduced 5-fold (p < 0.0005) in HMSN–ACC vs control RBCs, as a result of a lower Vmax (p < 0.05) rather than a lower Km (p = 0.109), accompanied by corresponding differences in Cl activation. Low intracellular Mg activated KCC in 6 out of 7 controls vs 1 out of 6 HMSN–ACC RBCs, suggesting that regulation is compromised. The lack of differences in staurosporine-activated KCC indicates different action mechanisms. Thus, in HMSN–ACC patients with KCC3 mutants, RBC KCC activity, although indistinguishable from that of the control group, responded differently to biochemical stressors, such as thiol alkylation or Mg removal, thereby indirectly indicating an important contribution of KCC3 to overall KCC function and regulation.
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Affiliation(s)
- P K Lauf
- Cell Biophysics Group, Department of Pathology, Wright State University, Boonshoft School of Medicine, 3640 Col Glenn Hwy, Dayton, OH 45435, USA.
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Klein T, Cooper TG, Yeung CH. The role of potassium chloride cotransporters in murine and human sperm volume regulation. Biol Reprod 2006; 75:853-8. [PMID: 16943364 DOI: 10.1095/biolreprod.106.054064] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Spermatozoa need to undergo regulatory volume decrease (RVD) upon ejaculation to counteract swelling due to the hypo-osmolality of female tract fluids. Defects in sperm RVD lead to failure in both cervical mucus penetration in humans and utero-tubal junction passage in mice. The role of K/Cl cotransporters (KCCs) in RVD was investigated by incubation of spermatozoa from the murine cauda epididymidis and from human ejaculates in media mimicking female tract fluid osmolalities in the presence of KCC inhibitors. Furosemide at 100 microM or more caused swelling of murine spermatozoa as detected with a flow cytometer by increased laser forward scatter over 30 to 75 min of incubation. Bumetanide, known to have low affinity for KCCs, was effective at 1 mM, whereas 10 microM and 20 microM of the specific inhibitor DIOA (dihydroindenyl-oxy alkanoic acid) increased cell volume. These drug doses were ineffective in human spermatozoa, which, however, responded to quinine, confirming the occurrence of RVD under control conditions. The molecular identity of the murine KCC isoform involved was determined at both mRNA and protein levels. Conventional RT-PCR indicated the presence of transcripts from Slc12a4 (KCC1), Slc12a6 (KCC3), and Slc12a7 (KCC4) in the testis, whereas RT-nested PCR revealed the latter two isoforms in sperm mRNA. Of these three isoforms, only SLC12A7 (KCC4) was detected in murine sperm protein by Western blotting. Therefore, besides organic osmolyte efflux and KCl release through separate K(+) and Cl(-) ion channels, SLC12A7 also is involved in murine but not human sperm RVD mechanisms.
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Affiliation(s)
- T Klein
- Institute of Reproductive Medicine, University of Münster, D-48129 Münster, Germany
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Adragna NC, Ferrell CM, Zhang J, Di Fulvio M, Temprana CF, Sharma A, Fyffe REW, Cool DR, Lauf PK. Signal transduction mechanisms of K+-Cl- cotransport regulation and relationship to disease. Acta Physiol (Oxf) 2006; 187:125-39. [PMID: 16734749 DOI: 10.1111/j.1748-1716.2006.01560.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The K+-Cl- cotransport (COT) regulatory pathways recently uncovered in our laboratory and their implication in disease state are reviewed. Three mechanisms of K+-Cl- COT regulation can be identified in vascular cells: (1) the Li+-sensitive pathway, (2) the platelet-derived growth factor (PDGF)-sensitive pathway and (3) the nitric oxide (NO)-dependent pathway. Ion fluxes, Western blotting, semi-quantitative RT-PCR, immunofluorescence and confocal microscopy were used. Li+, used in the treatment of manic depression, stimulates volume-sensitive K+-Cl- COT of low K+ sheep red blood cells at cellular concentrations <1 mM and inhibits at >3 mM, causes cell swelling, and appears to regulate K+-Cl- COT through a protein kinase C-dependent pathway. PDGF, a potent serum mitogen for vascular smooth muscle cells (VSMCs), regulates membrane transport and is involved in atherosclerosis. PDGF stimulates VSM K+-Cl- COT in a time- and concentration-dependent manner, both acutely and chronically, through the PDGF receptor. The acute effect occurs at the post-translational level whereas the chronic effect may involve regulation through gene expression. Regulation by PDGF involves the signalling molecules phosphoinositides 3-kinase and protein phosphatase-1. Finally, the NO/cGMP/protein kinase G pathway, involved in vasodilation and hence cardiovascular disease, regulates K+-Cl- COT in VSMCs at the mRNA expression and transport levels. A complex and diverse array of mechanisms and effectors regulate K+-Cl- COT and thus cell volume homeostasis, setting the stage for abnormalities at the genetic and/or regulatory level thus effecting or being affected by various pathological conditions.
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Affiliation(s)
- N C Adragna
- Cell Biophysics Group, Wright State University School of Medicine, Dayton, OH 45435, USA.
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Mercado A, Vázquez N, Song L, Cortés R, Enck AH, Welch R, Delpire E, Gamba G, Mount DB. NH2-terminal heterogeneity in the KCC3 K+-Cl− cotransporter. Am J Physiol Renal Physiol 2005; 289:F1246-61. [PMID: 16048901 DOI: 10.1152/ajprenal.00464.2004] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The SLC12A6 gene encoding the K+-Cl− cotransporter KCC3 is expressed in multiple tissues, including kidney. Here, we report the molecular characterization of several NH2-terminal isoforms of human and mouse KCC3, along with intrarenal localization and functional characterization in Xenopus laevis oocytes. Two major isoforms, KCC3a and KCC3b, are generated by transcriptional initiation 5′ of two distinct first coding exons. Northern blot analysis of mouse tissues indicates that KCC3b expression is particularly robust in the kidney, which also expresses KCC3a. Western blotting of mouse tissue using an exon 3-specific antibody reveals that the kidney is also unique in expressing immunoreactive protein of a lower mass, suggestive evidence that the shorter KCC3b protein predominates in kidney. Immunofluorescence reveals basolateral expression of KCC3 protein along the entire length of the proximal tubule, in both the mouse and rat. Removal of the 15-residue exon 2 by alternative splicing generates the KCC3a-x2M and KCC3b-x2M isoforms; other splicing events at an alternative acceptor site within exon 1a generate the KCC3a-S isoform, which is 60 residues shorter than KCC3a. This variation in sequence of NH2-terminal cytoplasmic domains occurs proximal to a stretch of highly conserved residues and affects the content of putative phosphorylation sites. Kinetic characterization of KCC3a in X. laevis oocytes reveals apparent Kms for Rb+ and Cl− of 10.7 ± 2.5 and 7.3 ± 1.2 mM, respectively, with an anion selectivity of Br− > Cl− > PO4 = I− = SCN− = gluconate. All five NH2-terminal isoforms are activated by cell swelling (hypotonic conditions), with no activity under isotonic conditions. Although the isoforms do not differ in the osmotic set point of swelling activation, this activation is more rapid for the KCC3a-x2M and KCC3a-S proteins. In summary, there is significant NH2-terminal heterogeneity of KCC3, with particularly robust expression of KCC3b in the kidney. Basolateral swelling-activated K+-Cl− cotransport mediated by KCC3 likely functions in cell volume regulation during the transepithelial transport of both salt and solutes by the proximal tubule.
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Affiliation(s)
- Adriana Mercado
- Renal Division, Brigham and Women's Hospital, Boston, MA 02115, USA
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