1
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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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2
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Schellinger JN, Sun Q, Pleinis JM, An SW, Hu J, Mercenne G, Titos I, Huang CL, Rothenfluh A, Rodan AR. Chloride oscillation in pacemaker neurons regulates circadian rhythms through a chloride-sensing WNK kinase signaling cascade. Curr Biol 2022; 32:1429-1438.e6. [PMID: 35303418 PMCID: PMC8972083 DOI: 10.1016/j.cub.2022.03.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/02/2021] [Accepted: 03/04/2022] [Indexed: 12/21/2022]
Abstract
Central pacemaker neurons regulate circadian rhythms and undergo diurnal variation in electrical activity in mammals and flies.1,2 Circadian variation in the intracellular chloride concentration of mammalian pacemaker neurons has been proposed to influence the response to GABAergic neurotransmission through GABAA receptor chloride channels.3 However, results have been contradictory,4-9 and a recent study demonstrated circadian variation in pacemaker neuron chloride without an effect on GABA response.10 Therefore, whether and how intracellular chloride regulates circadian rhythms remains controversial. Here, we demonstrate a signaling role for intracellular chloride in the Drosophila small ventral lateral (sLNv) pacemaker neurons. In control flies, intracellular chloride increases in sLNvs over the course of the morning. Chloride transport through sodium-potassium-2-chloride (NKCC) and potassium-chloride (KCC) cotransporters is a major determinant of intracellular chloride concentrations.11Drosophila melanogaster with loss-of-function mutations in the NKCC encoded by Ncc69 have abnormally low intracellular chloride 6 h after lights on, loss of morning anticipation, and a prolonged circadian period. Loss of kcc, which is expected to increase intracellular chloride, suppresses the long-period phenotype of Ncc69 mutant flies. Activation of a chloride-inhibited kinase cascade, consisting of WNK (with no lysine [K]) kinase and its downstream substrate, Fray, is necessary and sufficient to prolong period length. Fray activation of an inwardly rectifying potassium channel, Irk1, is also required for the long-period phenotype. These results indicate that the NKCC-dependent rise in intracellular chloride in Drosophila sLNv pacemakers restrains WNK-Fray signaling and overactivation of an inwardly rectifying potassium channel to maintain normal circadian period length.
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Affiliation(s)
- Jeffrey N Schellinger
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern, Dallas, TX 75390, USA
| | - Qifei Sun
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern, Dallas, TX 75390, USA
| | - John M Pleinis
- Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA
| | - Sung-Wan An
- Department of Internal Medicine, Division of Nephrology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Jianrui Hu
- Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA
| | - Gaëlle Mercenne
- Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA
| | - Iris Titos
- Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA
| | - Chou-Long Huang
- Department of Internal Medicine, Division of Nephrology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Adrian Rothenfluh
- Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA; Department of Psychiatry, Huntsman Mental Health Institute, University of Utah, Salt Lake City, UT 84108, USA; Department of Neurobiology, University of Utah, Salt Lake City, UT 84112, USA; Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Aylin R Rodan
- Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA; Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA; Department of Internal Medicine, Division of Nephrology and Hypertension, University of Utah, Salt Lake City, UT 84132, USA; Medical Service, Veterans Affairs Salt Lake City Health Care System, Salt Lake City, UT 84148, USA.
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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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4
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Chi G, Ebenhoch R, Man H, Tang H, Tremblay LE, Reggiano G, Qiu X, Bohstedt T, Liko I, Almeida FG, Garneau AP, Wang D, McKinley G, Moreau CP, Bountra KD, Abrusci P, Mukhopadhyay SMM, Fernandez‐Cid A, Slimani S, Lavoie JL, Burgess‐Brown NA, Tehan B, DiMaio F, Jazayeri A, Isenring P, Robinson CV, Dürr KL. Phospho-regulation, nucleotide binding and ion access control in potassium-chloride cotransporters. EMBO J 2021; 40:e107294. [PMID: 34031912 PMCID: PMC8280820 DOI: 10.15252/embj.2020107294] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 03/29/2021] [Accepted: 04/11/2021] [Indexed: 11/26/2022] Open
Abstract
Potassium-coupled chloride transporters (KCCs) play crucial roles in regulating cell volume and intracellular chloride concentration. They are characteristically inhibited under isotonic conditions via phospho-regulatory sites located within the cytoplasmic termini. Decreased inhibitory phosphorylation in response to hypotonic cell swelling stimulates transport activity, and dysfunction of this regulatory process has been associated with various human diseases. Here, we present cryo-EM structures of human KCC3b and KCC1, revealing structural determinants for phospho-regulation in both N- and C-termini. We show that phospho-mimetic KCC3b is arrested in an inward-facing state in which intracellular ion access is blocked by extensive contacts with the N-terminus. In another mutant with increased isotonic transport activity, KCC1Δ19, this interdomain interaction is absent, likely due to a unique phospho-regulatory site in the KCC1 N-terminus. Furthermore, we map additional phosphorylation sites as well as a previously unknown ATP/ADP-binding pocket in the large C-terminal domain and show enhanced thermal stabilization of other CCCs by adenine nucleotides. These findings provide fundamentally new insights into the complex regulation of KCCs and may unlock innovative strategies for drug development.
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Affiliation(s)
- Gamma Chi
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Structural Genomics ConsortiumNuffield Department of MedicineUniversity of OxfordOxfordUK
| | - Rebecca Ebenhoch
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Structural Genomics ConsortiumNuffield Department of MedicineUniversity of OxfordOxfordUK
- Present address:
MedChem, Boehringer Ingelheim Pharma GmbH & Co. KGBiberachGermany
| | - Henry Man
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Structural Genomics ConsortiumNuffield Department of MedicineUniversity of OxfordOxfordUK
- Present address:
Exscientia LtdOxfordUK
| | - Haiping Tang
- Physical and Theoretical Chemistry LaboratoryUniversity of OxfordOxfordUK
| | - Laurence E Tremblay
- Department of MedicineNephrology Research GroupFaculty of MedicineLaval UniversityQuebec CityQCCanada
| | | | - Xingyu Qiu
- Physical and Theoretical Chemistry LaboratoryUniversity of OxfordOxfordUK
| | - Tina Bohstedt
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Structural Genomics ConsortiumNuffield Department of MedicineUniversity of OxfordOxfordUK
| | | | | | - Alexandre P Garneau
- Department of MedicineNephrology Research GroupFaculty of MedicineLaval UniversityQuebec CityQCCanada
- Cardiometabolic Axis, School of Kinesiology and Physical Activity SciencesUniversity of MontréalMontréalQCCanada
| | - Dong Wang
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Structural Genomics ConsortiumNuffield Department of MedicineUniversity of OxfordOxfordUK
| | - Gavin McKinley
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Structural Genomics ConsortiumNuffield Department of MedicineUniversity of OxfordOxfordUK
| | - Christophe P Moreau
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Present address:
Celonic AGBaselGermany
| | | | - Patrizia Abrusci
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Structural Genomics ConsortiumNuffield Department of MedicineUniversity of OxfordOxfordUK
- Present address:
Exscientia LtdOxfordUK
| | - Shubhashish M M Mukhopadhyay
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Structural Genomics ConsortiumNuffield Department of MedicineUniversity of OxfordOxfordUK
| | - Alejandra Fernandez‐Cid
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Structural Genomics ConsortiumNuffield Department of MedicineUniversity of OxfordOxfordUK
| | - Samira Slimani
- Department of MedicineNephrology Research GroupFaculty of MedicineLaval UniversityQuebec CityQCCanada
| | - Julie L Lavoie
- Cardiometabolic Axis, School of Kinesiology and Physical Activity SciencesUniversity of MontréalMontréalQCCanada
| | - Nicola A Burgess‐Brown
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Structural Genomics ConsortiumNuffield Department of MedicineUniversity of OxfordOxfordUK
| | | | - Frank DiMaio
- Department of BiochemistryUniversity of WashingtonSeattleWAUSA
| | | | - Paul Isenring
- Department of MedicineNephrology Research GroupFaculty of MedicineLaval UniversityQuebec CityQCCanada
| | - Carol V Robinson
- Physical and Theoretical Chemistry LaboratoryUniversity of OxfordOxfordUK
| | - Katharina L Dürr
- Nuffield Department of MedicineCentre of Medicines DiscoveryUniversity of OxfordOxfordUK
- Structural Genomics ConsortiumNuffield Department of MedicineUniversity of OxfordOxfordUK
- OMass Therapeutics, Ltd.OxfordUK
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5
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Noriega LG, Melo Z, Rajaram RD, Mercado A, Tovar AR, Velazquez‐Villegas LA, Castañeda‐Bueno M, Reyes‐López Y, Ryu D, Rojas‐Vega L, Magaña‐Avila G, López‐Barradas AM, Sánchez‐Hernández M, Debonneville A, Doucet A, Cheval L, Torres N, Auwerx J, Staub O, Gamba G. SIRT7 modulates the stability and activity of the renal K-Cl cotransporter KCC4 through deacetylation. EMBO Rep 2021; 22:e50766. [PMID: 33749979 PMCID: PMC8097349 DOI: 10.15252/embr.202050766] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 02/03/2021] [Accepted: 02/19/2021] [Indexed: 11/09/2022] Open
Abstract
SIRT7 is a NAD+ -dependent deacetylase that controls important aspects of metabolism, cancer, and bone formation. However, the molecular targets and functions of SIRT7 in the kidney are currently unknown. In silico analysis of kidney transcripts of the BXD murine genetic reference population revealed a positive correlation between Sirt7 and Slc12a7 mRNA expression, suggesting a link between the corresponding proteins that these transcripts encode, SIRT7, and the K-Cl cotransporter KCC4, respectively. Here, we find that protein levels and activity of heterologously expressed KCC4 are significantly modulated depending on its acetylation status in Xenopus laevis oocytes. Moreover, SIRT7 interacts with KCC4 in a NAD+ -dependent manner and increases its stability and activity in HEK293 cells. Interestingly, metabolic acidosis increases SIRT7 expression in kidney, as occurs with KCC4. In contrast, total SIRT7-deficient mice present lower KCC4 expression and an exacerbated metabolic acidosis than wild-type mice during an ammonium chloride challenge. Altogether, our data suggest that SIRT7 interacts with, stabilizes and modulates KCC4 activity through deacetylation, and reveals a novel role for SIRT7 in renal physiology.
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Affiliation(s)
- Lilia G Noriega
- Department of Nutrition PhysiologyInstituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico CityMexico
| | - Zesergio Melo
- Department of Nephrology and Mineral MetabolismInstituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico CityMexico
- CONACYT‐Centro de Investigación Biomédica de OccidenteInstituto Mexicano del Seguro SocialGuadalajaraJaliscoMexico
| | - Renuga D Rajaram
- Department of Pharmacology and ToxicologyUniversity of LausanneLausanneSwitzerland
- National Centre of Competence in Research, “Kidney.ch”ZurichSwitzerland
| | - Adriana Mercado
- Department of NephrologyInstituto Nacional de Cardiología Ignacio ChávezMexico CityMexico
| | - Armando R Tovar
- Department of Nutrition PhysiologyInstituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico CityMexico
| | - Laura A Velazquez‐Villegas
- Department of Nutrition PhysiologyInstituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico CityMexico
| | - María Castañeda‐Bueno
- Department of Nephrology and Mineral MetabolismInstituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico CityMexico
| | - Yazmín Reyes‐López
- Department of Nutrition PhysiologyInstituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico CityMexico
| | - Dongryeol Ryu
- Laboratory of Integrative and Systems Physiology (LISP)École Polytechnique Fédérale de LausanneLausanneSwitzerland
- Present address:
Department of Molecular Cell BiologySungkyunkwan University School of MedicineSuwonKorea
| | - Lorena Rojas‐Vega
- Department of Nephrology and Mineral MetabolismInstituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico CityMexico
| | - German Magaña‐Avila
- Department of Nephrology and Mineral MetabolismInstituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico CityMexico
| | - Adriana M López‐Barradas
- Department of Nutrition PhysiologyInstituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico CityMexico
| | | | - Anne Debonneville
- Department of Pharmacology and ToxicologyUniversity of LausanneLausanneSwitzerland
- National Centre of Competence in Research, “Kidney.ch”ZurichSwitzerland
| | - Alain Doucet
- Centre de Recherche des CordeliersINSERM, Sorbonne Universités, USPC, Université Paris Descartes, Université Paris Diderot, Physiologie Rénale et TubulopathiesCNRS ERL 8228ParisFrance
| | - Lydie Cheval
- Centre de Recherche des CordeliersINSERM, Sorbonne Universités, USPC, Université Paris Descartes, Université Paris Diderot, Physiologie Rénale et TubulopathiesCNRS ERL 8228ParisFrance
| | - Nimbe Torres
- Department of Nutrition PhysiologyInstituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico CityMexico
| | - Johan Auwerx
- Laboratory of Integrative and Systems Physiology (LISP)École Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Olivier Staub
- Department of Pharmacology and ToxicologyUniversity of LausanneLausanneSwitzerland
- National Centre of Competence in Research, “Kidney.ch”ZurichSwitzerland
| | - Gerardo Gamba
- Department of Nephrology and Mineral MetabolismInstituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico CityMexico
- Molecular Physiology UnitInstituto de Investigaciones BiomédicasUniversidad Nacional Autónoma de MéxicoMexico CityMexico
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6
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Dzhala VI, Staley KJ. KCC2 Chloride Transport Contributes to the Termination of Ictal Epileptiform Activity. eNeuro 2021; 8:ENEURO.0208-20.2020. [PMID: 33239270 PMCID: PMC7986536 DOI: 10.1523/eneuro.0208-20.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 01/10/2023] Open
Abstract
Recurrent seizures intensely activate GABAA receptors (GABAA-Rs), which induces transient neuronal chloride ([Cl-]i) elevations and depolarizing GABA responses that contribute to the failure of inhibition that engenders further seizures and anticonvulsant resistance. The K+-Cl- cotransporter KCC2 is responsible for Cl- extrusion and restoration of [Cl-]i equilibrium (ECl) after synaptic activity, but at the cost of increased extracellular potassium which may retard K+-Cl- extrusion, depolarize neurons, and potentiate seizures. Thus, KCC2 may either diminish or facilitate seizure activity, and both proconvulsant and anticonvulsant effects of KCC2 inhibition have been reported. It is now necessary to identify the loci of these divergent responses by assaying both the electrographic effects and the ionic effects of KCC2 manipulation. We therefore determined the net effects of KCC2 transport activity on cytoplasmic chloride elevation and Cl- extrusion rates during spontaneous recurrent ictal-like epileptiform discharges (ILDs) in organotypic hippocampal slices in vitro, as well as the correlation between ionic and electrographic effects. We found that the KCC2 antagonist VU0463271 reduced Cl- extrusion rates, increased ictal [Cl-]i elevation, increased ILD duration, and induced status epilepticus (SE). In contrast, the putative KCC2 upregulator CLP257 improved chloride homeostasis and reduced the duration and frequency of ILDs in a concentration-dependent manner. Our results demonstrate that measuring both the ionic and electrographic effects of KCC2 transport clarify the impact of KCC2 modulation in specific models of epileptiform activity. Anticonvulsant effects predominate when KCC2-mediated chloride transport rather than potassium buffering is the rate-limiting step in restoring ECl and the efficacy of GABAergic inhibition during recurrent ILDs.
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Affiliation(s)
- Volodymyr I Dzhala
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114
- Harvard Medical School, Boston, MA 02114
| | - Kevin J Staley
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114
- Harvard Medical School, Boston, MA 02114
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7
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Zhang S, Zhou J, Zhang Y, Liu T, Friedel P, Zhuo W, Somasekharan S, Roy K, Zhang L, Liu Y, Meng X, Deng H, Zeng W, Li G, Forbush B, Yang M. The structural basis of function and regulation of neuronal cotransporters NKCC1 and KCC2. Commun Biol 2021; 4:226. [PMID: 33597714 PMCID: PMC7889885 DOI: 10.1038/s42003-021-01750-w] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 01/22/2021] [Indexed: 11/08/2022] Open
Abstract
NKCC and KCC transporters mediate coupled transport of Na++K++Cl- and K++Cl- across the plasma membrane, thus regulating cell Cl- concentration and cell volume and playing critical roles in transepithelial salt and water transport and in neuronal excitability. The function of these transporters has been intensively studied, but a mechanistic understanding has awaited structural studies of the transporters. Here, we present the cryo-electron microscopy (cryo-EM) structures of the two neuronal cation-chloride cotransporters human NKCC1 (SLC12A2) and mouse KCC2 (SLC12A5), along with computational analysis and functional characterization. These structures highlight essential residues in ion transport and allow us to propose mechanisms by which phosphorylation regulates transport activity.
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Affiliation(s)
- Sensen Zhang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Jun Zhou
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yuebin Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Tianya Liu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Perrine Friedel
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
| | - Wei Zhuo
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Suma Somasekharan
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
| | - Kasturi Roy
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
| | - Laixing Zhang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yang Liu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xianbin Meng
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, China
| | - Haiteng Deng
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, China
| | - Wenwen Zeng
- Center for Life Sciences, Institute for Immunology and School of Medicine, Tsinghua University, Beijing, China
| | - Guohui Li
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
| | - Biff Forbush
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA.
| | - Maojun Yang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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8
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Josiah SS, Meor Azlan NF, Zhang J. Targeting the WNK-SPAK/OSR1 Pathway and Cation-Chloride Cotransporters for the Therapy of Stroke. Int J Mol Sci 2021; 22:1232. [PMID: 33513812 PMCID: PMC7865768 DOI: 10.3390/ijms22031232] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/22/2021] [Accepted: 01/24/2021] [Indexed: 02/05/2023] Open
Abstract
Stroke is one of the major culprits responsible for morbidity and mortality worldwide, and the currently available pharmacological strategies to combat this global disease are scanty. Cation-chloride cotransporters (CCCs) are expressed in several tissues (including neurons) and extensively contribute to the maintenance of numerous physiological functions including chloride homeostasis. Previous studies have implicated two CCCs, the Na+-K+-Cl- and K+-Cl- cotransporters (NKCCs and KCCs) in stroke episodes along with their upstream regulators, the with-no-lysine kinase (WNKs) family and STE20/SPS1-related proline/alanine rich kinase (SPAK) or oxidative stress response kinase (OSR1) via a signaling pathway. As the WNK-SPAK/OSR1 pathway reciprocally regulates NKCC and KCC, a growing body of evidence implicates over-activation and altered expression of NKCC1 in stroke pathology whilst stimulation of KCC3 during and even after a stroke event is neuroprotective. Both inhibition of NKCC1 and activation of KCC3 exert neuroprotection through reduction in intracellular chloride levels and thus could be a novel therapeutic strategy. Hence, this review summarizes the current understanding of functional regulations of the CCCs implicated in stroke with particular focus on NKCC1, KCC3, and WNK-SPAK/OSR1 signaling and discusses the current and potential pharmacological treatments for stroke.
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Affiliation(s)
| | | | - Jinwei Zhang
- Hatherly Laboratories, Institute of Biomedical and Clinical Sciences, Medical School, College of Medicine and Health, University of Exeter, Exeter EX4 4PS, UK; (S.S.J.); (N.F.M.A.)
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9
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Chakraborty M, Asraf H, Sekler I, Hershfinkel M. ZnR/GPR39 controls cell migration by orchestrating recruitment of KCC3 into protrusions, re-organization of actin and activation of MMP. Cell Calcium 2021; 94:102330. [PMID: 33465674 DOI: 10.1016/j.ceca.2020.102330] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/16/2020] [Accepted: 11/30/2020] [Indexed: 12/23/2022]
Abstract
Actin re-organization and degradation of extracellular matrix by metalloproteases (MMPs) facilitate formation of cellular protrusions that are required for cell proliferation and migration. We find that Zn2+ activation of the Gq-coupled receptor ZnR/GPR39 controls these processes by regulating K+/Cl- co-transporter KCC3, which modulates cell volume. Silencing of KCC3 expression or activity reverses ZnR/GPR39 enhancement of cell proliferation, migration and invasion through Matrigel. Activation of ZnR/GPR39 recruits KCC3 into F-actin rich membrane protrusions, suggesting that it can locally control volume changes. Immunofluorescence analysis indicates that Zn2+ activation of ZnR/GPR39 and KCC3 are required to enhance formation of F-actin stress fibers and cellular protrusions. In addition, ZnR/GPR39 upregulation of KCC3-dependent transport increases the activity of matrix metalloproteases MMP2 and MMP9. Our study establishes a mechanism in which ZnR/GPR39 orchestrates localization and activation of KCC3, formation of F-actin rich cell protrusions and activation of MMPs, and thereby controls cell proliferation and migration.
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Affiliation(s)
- Moumita Chakraborty
- 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
| | - 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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10
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McFarlin BE, Chen Y, Priver TS, Ralph DL, Mercado A, Gamba G, Madhur MS, McDonough AA. Coordinate adaptations of skeletal muscle and kidney to maintain extracellular [K +] during K +-deficient diet. Am J Physiol Cell Physiol 2020; 319:C757-C770. [PMID: 32845718 PMCID: PMC7654654 DOI: 10.1152/ajpcell.00362.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/17/2020] [Accepted: 08/19/2020] [Indexed: 12/16/2022]
Abstract
Extracellular fluid (ECF) potassium concentration ([K+]) is maintained by adaptations of kidney and skeletal muscle, responses heretofore studied separately. We aimed to determine how these organ systems work in concert to preserve ECF [K+] in male C57BL/6J mice fed a K+-deficient diet (0K) versus 1% K+ diet (1K) for 10 days (n = 5-6/group). During 0K feeding, plasma [K+] fell from 4.5 to 2 mM; hindlimb muscle (gastrocnemius and soleus) lost 28 mM K+ (from 115 ± 2 to 87 ± 2 mM) and gained 27 mM Na+ (from 27 ± 0.4 to 54 ± 2 mM). Doubling of muscle tissue [Na+] was not associated with inflammation, cytokine production or hypertension as reported by others. Muscle transporter adaptations in 0K- versus 1K-fed mice, assessed by immunoblot, included decreased sodium pump α2-β2 subunits, decreased K+-Cl- cotransporter isoform 3, and increased phosphorylated (p) Na+,K+,2Cl- cotransporter isoform 1 (NKCC1p), Ste20/SPS-1-related proline-alanine rich kinase (SPAKp), and oxidative stress-responsive kinase 1 (OSR1p) consistent with intracellular fluid (ICF) K+ loss and Na+ gain. Renal transporters' adaptations, effecting a 98% reduction in K+ excretion, included two- to threefold increased phosphorylated Na+-Cl- cotransporter (NCCp), SPAKp, and OSR1p abundance, limiting Na+ delivery to epithelial Na+ channels where Na+ reabsorption drives K+ secretion; and renal K sensor Kir 4.1 abundance fell 25%. Mass balance estimations indicate that over 10 days of 0K feeding, mice lose ~48 μmol K+ into the urine and muscle shifts ~47 μmol K+ from ICF to ECF, illustrating the importance of the concerted responses during K+ deficiency.
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Affiliation(s)
- Brandon E McFarlin
- Department of Physiology and Neuroscience, Keck School of Medicine of the University of Southern California, Los Angeles, California
| | - Yuhan Chen
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Cardiology, Nanjing University Medical School, Nanjing, China
| | - Taylor S Priver
- Department of Physiology and Neuroscience, Keck School of Medicine of the University of Southern California, Los Angeles, California
| | - Donna L Ralph
- Department of Physiology and Neuroscience, Keck School of Medicine of the University of Southern California, Los Angeles, California
| | - Adriana Mercado
- Department of Nephrology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico
| | - 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 City, Mexico
| | - Meena S Madhur
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Alicia A McDonough
- Department of Physiology and Neuroscience, Keck School of Medicine of the University of Southern California, Los Angeles, California
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11
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Su XT, Klett NJ, Sharma A, Allen CN, Wang WH, Yang CL, Ellison DH. Distal convoluted tubule Cl - concentration is modulated via K + channels and transporters. Am J Physiol Renal Physiol 2020; 319:F534-F540. [PMID: 32715757 DOI: 10.1152/ajprenal.00284.2020] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cl--sensitive with-no-lysine kinase (WNK) plays a key role in regulating the thiazide-sensitive Na+-Cl- cotransporter (NCC) in the distal convoluted tubule (DCT). Cl- enters DCT cells through NCC and leaves the cell across the basolateral membrane via the Cl- channel ClC-K2 or K+-Cl- cotransporter (KCC). While KCC is electroneutral, Cl- exit via ClC-K2 is electrogenic. Therefore, an alteration in DCT basolateral K+ channel activity is expected to influence Cl- movement across the basolateral membrane. Although a role for intracellular Cl- in the regulation of WNK and NCC has been established, intracellular Cl- concentrations ([Cl-]i) have not been directly measured in the mammalian DCT. Therefore, to measure [Cl-]i in DCT cells, we generated a transgenic mouse model expressing an optogenetic kidney-specific Cl-Sensor and measured Cl- fluorescent imaging in the isolated DCT. Basal measurements indicated that the mean [Cl-]i was ~7 mM. Stimulation of Cl- exit with low-Cl- hypotonic solutions decreased [Cl-]i, whereas inhibition of KCC by DIOA or inhibition of ClC-K2 by NPPB increased [Cl-]i, suggesting roles for both KCC and ClC-K2 in the modulation of [Cl-]i . Blockade of basolateral K+ channels (Kir4.1/5.1) with barium significantly increased [Cl-]i. Finally, a decrease in extracellular K+ concentration transiently decreased [Cl-]i, whereas raising extracellular K+ transiently increased [Cl-]i, further suggesting a role for Kir4.1/5.1 in the regulation of [Cl-]i. We conclude that the alteration in ClC-K2, KCC, and Kir4.1/5.1 activity influences [Cl-]i in the DCT.
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Affiliation(s)
- Xiao-Tong Su
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Nathan J Klett
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Avika Sharma
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Charles N Allen
- Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, Oregon.,Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University, Portland, Oregon
| | - David H Ellison
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University, Portland, Oregon.,Veterans Administration Portland Health Care System, Portland, Oregon
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12
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Reid MS, Kern DM, Brohawn SG. Cryo-EM structure of the potassium-chloride cotransporter KCC4 in lipid nanodiscs. eLife 2020; 9:e52505. [PMID: 32286222 PMCID: PMC7200160 DOI: 10.7554/elife.52505] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 04/12/2020] [Indexed: 01/24/2023] Open
Abstract
Cation-chloride-cotransporters (CCCs) catalyze transport of Cl- with K+ and/or Na+across cellular membranes. CCCs play roles in cellular volume regulation, neural development and function, audition, regulation of blood pressure, and renal function. CCCs are targets of clinically important drugs including loop diuretics and their disruption has been implicated in pathophysiology including epilepsy, hearing loss, and the genetic disorders Andermann, Gitelman, and Bartter syndromes. Here we present the structure of a CCC, the Mus musculus K+-Cl- cotransporter (KCC) KCC4, in lipid nanodiscs determined by cryo-EM. The structure, captured in an inside-open conformation, reveals the architecture of KCCs including an extracellular domain poised to regulate transport activity through an outer gate. We identify binding sites for substrate K+ and Cl- ions, demonstrate the importance of key coordinating residues for transporter activity, and provide a structural explanation for varied substrate specificity and ion transport ratio among CCCs. These results provide mechanistic insight into the function and regulation of a physiologically important transporter family.
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Affiliation(s)
- Michelle S Reid
- Department of Molecular and Cell Biology, University of California BerkeleyBerkeleyUnited States
- Helen Wills Neuroscience Institute, University of California BerkeleyBerkeleyUnited States
| | - David M Kern
- Department of Molecular and Cell Biology, University of California BerkeleyBerkeleyUnited States
- Helen Wills Neuroscience Institute, University of California BerkeleyBerkeleyUnited States
| | - Stephen Graf Brohawn
- Department of Molecular and Cell Biology, University of California BerkeleyBerkeleyUnited States
- Helen Wills Neuroscience Institute, University of California BerkeleyBerkeleyUnited States
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13
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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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14
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Garneau AP, Slimani S, Tremblay LE, Fiola MJ, Marcoux AA, Isenring P. K +-Cl - cotransporter 1 (KCC1): a housekeeping membrane protein that plays key supplemental roles in hematopoietic and cancer cells. J Hematol Oncol 2019; 12:74. [PMID: 31296230 PMCID: PMC6624878 DOI: 10.1186/s13045-019-0766-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 06/30/2019] [Indexed: 01/04/2023] Open
Abstract
During the 1970s, a Na+-independent, ouabain-insensitive, N-ethylmaleimide-stimulated K+-Cl- cotransport mechanism was identified in red blood cells for the first time and in a variety of cell types afterward. During and just after the mid-1990s, three closely related isoforms were shown to account for this mechanism. They were termed K+-Cl- cotransporter 1 (KCC1), KCC3, and KCC4 according to the nomenclature of Gillen et al. (1996) who had been the first research group to uncover the molecular identity of a KCC, that is, of KCC1 in rabbit kidney. Since then, KCC1 has been found to be the most widely distributed KCC isoform and considered to act as a housekeeping membrane protein. It has perhaps received less attention than the other isoforms for this reason, but as will be discussed in the following review, there is probably more to KCC1 than meets the eye. In particular, the so-called housekeeping gene also appears to play crucial and specific roles in normal as well as pathological hematopoietic and in cancer cells.
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Affiliation(s)
- A P Garneau
- From the Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), G1R 2J6, Canada
- Cardiometabolic Axis, School of Kinesiology and Physical Activity Sciences, University of Montréal, 900, rue Saint-Denis, Montréal (Qc), H2X 0A9, Canada
| | - S Slimani
- From the Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), G1R 2J6, Canada
| | - L E Tremblay
- From the Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), G1R 2J6, Canada
| | - M J Fiola
- From the Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), G1R 2J6, Canada
| | - A A Marcoux
- From the Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), G1R 2J6, Canada
| | - P Isenring
- From the Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), G1R 2J6, Canada.
- L'Hôtel-Dieu de Québec Institution, 10, rue McMahon, Québec (Qc), G1R 2J6, Canada.
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15
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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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16
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Garneau AP, Marcoux AA, Slimani S, Tremblay LE, Frenette-Cotton R, Mac-Way F, Isenring P. Physiological roles and molecular mechanisms of K + -Cl - cotransport in the mammalian kidney and cardiovascular system: where are we? J Physiol 2019; 597:1451-1465. [PMID: 30659612 DOI: 10.1113/jp276807] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 12/07/2018] [Indexed: 11/08/2022] Open
Abstract
In the early 80s, renal microperfusion studies led to the identification of a basolateral K+ -Cl- cotransport mechanism in the proximal tubule, thick ascending limb of Henle and collecting duct. More than ten years later, this mechanism was found to be accounted for by three different K+ -Cl- cotransporters (KCC1, KCC3 and KCC4) that are differentially distributed along the renal epithelium. Two of these isoforms (KCC1 and KCC3) were also found to be expressed in arterial walls, the myocardium and a variety of neurons. Subsequently, valuable insights have been gained into the molecular and physiological properties of the KCCs in both the mammalian kidney and cardiovascular system. There is now robust evidence indicating that KCC4 sustains distal renal acidification and that KCC3 regulates myogenic tone in resistance vessels. However, progress in understanding the functional significance of these transporters has been slow, probably because each of the KCC isoforms is not identically distributed among species and some of them share common subcellular localizations with other KCC isoforms or sizeable conductive Cl- pathways. In addition, the mechanisms underlying the process of K+ -Cl- cotransport are still ill defined. The present review focuses on the knowledge gained regarding the roles and properties of KCCs in renal and cardiovascular tissues.
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Affiliation(s)
- A P Garneau
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6.,Cardiometabolic Axis, School of Kinesiology and Physical Activity Sciences, Montreal University, 900, rue Saint-Denis, Montréal, (Qc) H2X 0A9
| | - A A Marcoux
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - S Slimani
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - L E Tremblay
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - R Frenette-Cotton
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - F Mac-Way
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - P Isenring
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
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17
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Cordshagen A, Busch W, Winklhofer M, Nothwang HG, Hartmann AM. Phosphoregulation of the intracellular termini of K +-Cl - cotransporter 2 (KCC2) enables flexible control of its activity. J Biol Chem 2018; 293:16984-16993. [PMID: 30201606 DOI: 10.1074/jbc.ra118.004349] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/01/2018] [Indexed: 12/22/2022] Open
Abstract
The pivotal role of K+-Cl- cotransporter 2 (KCC2) in inhibitory neurotransmission and severe human diseases fosters interest in understanding posttranslational regulatory mechanisms such as (de)phosphorylation. Here, the regulatory role of the five bona fide phosphosites Ser31, Thr34, Ser932, Thr999, and Thr1008 was investigated by the use of alanine and aspartate mutants. Tl+-based flux analyses in HEK-293 cells demonstrated increased transport activity for S932D (mimicking phosphorylation) and T1008A (mimicking dephosphorylation), albeit to a different extent. Increased activity was due to changes in intrinsic activity, as it was not caused by increased cell-surface abundance. Substitutions of Ser31, Thr34, or Thr999 had no effect. Additionally, we show that the indirect actions of the known KCC2 activators staurosporine and N-ethylmaleimide (NEM) involved multiple phosphosites. S31D, T34A, S932A/D, T999A, or T1008A/D abrogated staurosporine mediated stimulation, and S31A, T34D, or S932D abolished NEM-mediated stimulation. This demonstrates for the first time differential effects of staurosporine and NEM on KCC2. In addition, the staurosporine-mediated effects involved both KCC2 phosphorylation and dephosphorylation with Ser932 and Thr1008 being bona fide target sites. In summary, our data reveal a complex phosphoregulation of KCC2 that provides the transporter with a toolbox for graded activity and integration of different signaling pathways.
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Affiliation(s)
- Antje Cordshagen
- From the Neurogenetics group, Center of Excellence Hearing4all, School of Medicine and Health Sciences
| | - Wiebke Busch
- From the Neurogenetics group, Center of Excellence Hearing4all, School of Medicine and Health Sciences
| | - Michael Winklhofer
- Institute for Biology and Environmental Sciences IBU, and.,Research Center for Neurosensory Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
| | - Hans Gerd Nothwang
- From the Neurogenetics group, Center of Excellence Hearing4all, School of Medicine and Health Sciences.,Research Center for Neurosensory Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
| | - Anna-Maria Hartmann
- From the Neurogenetics group, Center of Excellence Hearing4all, School of Medicine and Health Sciences, .,Research Center for Neurosensory Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
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18
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de Los Heros P, Pacheco-Alvarez D, Gamba G. Role of WNK Kinases in the Modulation of Cell Volume. CURRENT TOPICS IN MEMBRANES 2018; 81:207-235. [PMID: 30243433 DOI: 10.1016/bs.ctm.2018.08.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Ion Transport across the cell membrane is required to maintain cell volume homeostasis. In response to changes in extracellular osmolarity, most cells activate specific metabolic or membrane-transport pathways to respond to cell swelling or shrinkage and return their volume to its normal resting state. This process involves the rapid adjustment of the activities of channels and transporters that mediate flux of K+, Na+, Cl-, and small organic osmolytes. Cation chloride cotransporters (CCCs) NKCCs and KCCs are a family of membrane proteins modulated by changes in cell volume and/or in the intracellular chloride concentration ([Cl-]i). Cell swelling triggers regulatory volume decrease (RVD), promoting solute and water efflux to restore normal cell volume. Swelling-activated KCCs mediate RVD in most cell types. In contrast, cell shrinkage triggers regulatory volume increase (RVI), which involves the activation of the NKCC1 cotransporter of the CCC family. Regulation of the CCCs during RVI and RVD by protein phosphorylation is a well-characterized mechanism, where WNK kinases and their downstream kinase substrates, SPAK and OSR1 constitute the essential phospho-regulators. WNKs-SPAK/OSR1-CCCs complex is required to regulate cell shrinkage-induced RVI or cell swelling-induced RVD via activating or inhibitory phosphorylation of NKCCs or KCCs, respectively. WNK1 and WNK4 kinases have been established as [Cl-]i sensors/regulators, while a role for WNK3 kinase as a cell volume-sensing kinase has emerged and is proposed in this chapter.
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Affiliation(s)
- Paola de Los Heros
- División de Investigación, Facultad de Medicina, Universidad Nacional Autónoma de México, Coyoacán, Mexico City, Mexico
| | | | - 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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19
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Frenette-Cotton R, Marcoux AA, Garneau AP, Noel M, Isenring P. Phosphoregulation of K + -Cl - cotransporters during cell swelling: Novel insights. J Cell Physiol 2018; 233:396-408. [PMID: 28276587 DOI: 10.1002/jcp.25899] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 03/06/2017] [Indexed: 01/21/2023]
Abstract
The K+ -Cl- cotransporters (KCCs) belong to the cation-Cl- cotransporter family and consist of four isoforms and many splice variants. Their main role is to promote electroneutral efflux of K+ and Cl- ions across the surface of many cell types and, thereby, to regulate intracellular ion concentration, cell volume, and epithelial salt movement. These transport systems are induced by an increase in cell volume and are less active at lower intracellular [Cl- ] (Cli ), but the mechanisms at play are still ill-defined. In this work, we have exploited the Xenopus laevis expression system to study the role of lysine-deficient protein kinases (WNKs), protein phosphatases 1 (PP1s), and SPS1-related proline/alanine-rich kinase (SPAK) in KCC4 regulation during cell swelling. We have found that WNK4 and PP1 regulate KCC4 activity as part of a common signaling module, but that they do not exert their effects through SPAK or carrier dephosphorylation. We have also found that the phosphatases at play include PP1α and PP1γ1, but that WNK4 acts directly on the PP1s instead of the opposite. Unexpectedly, however, both cell swelling and a T926A substitution in the C-terminus of full-length KCC4 led to higher levels of heterologous K+ -Cl- cotransport and overall carrier phosphorylation. These results imply that the response to cell swelling must also involve allosteric-sensitive kinase-dependent phosphoacceptor sites in KCC4. They are thus partially inconsistent with previous models of KCC regulation.
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Affiliation(s)
| | - Andrée-Anne Marcoux
- Nephrology Research Group, Department of Medicine, Laval University, Québec, Québec, Canada
| | - Alexandre P Garneau
- Nephrology Research Group, Department of Medicine, Laval University, Québec, Québec, Canada
| | - Micheline Noel
- Nephrology Research Group, Department of Medicine, Laval University, Québec, Québec, Canada
| | - Paul Isenring
- Nephrology Research Group, Department of Medicine, Laval University, Québec, Québec, Canada
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20
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Garneau AP, Marcoux AA, Frenette-Cotton R, Mac-Way F, Lavoie JL, Isenring P. Molecular insights into the normal operation, regulation, and multisystemic roles of K +-Cl - cotransporter 3 (KCC3). Am J Physiol Cell Physiol 2017; 313:C516-C532. [PMID: 28814402 DOI: 10.1152/ajpcell.00106.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 07/26/2017] [Accepted: 08/14/2017] [Indexed: 12/12/2022]
Abstract
Long before the molecular identity of the Na+-dependent K+-Cl- cotransporters was uncovered in the mid-nineties, a Na+-independent K+-Cl- cotransport system was also known to exist. It was initially observed in sheep and goat red blood cells where it was shown to be ouabain-insensitive and to increase in the presence of N-ethylmaleimide (NEM). After it was established between the early and mid-nineties, the expressed sequence tag (EST) databank was found to include a sequence that was highly homologous to those of the Na+-dependent K+-Cl- cotransporters. This sequence was eventually found to code for the Na+-independent K+-Cl- cotransport function that was described in red blood cells several years before. It was termed KCC1 and led to the discovery of three isoforms called KCC2, KCC3, and KCC4. Since then, it has become obvious that each one of these isoforms exhibits unique patterns of distribution and fulfills distinct physiological roles. Among them, KCC3 has been the subject of great attention in view of its important role in the nervous system and its association with a rare hereditary sensorimotor neuropathy (called Andermann syndrome) that affects many individuals in Quebec province (Canada). It was also found to play important roles in the cardiovascular system, the organ of Corti, and circulating blood cells. As will be seen in this review, however, there are still a number of uncertainties regarding the transport properties, structural organization, and regulation of KCC3. The same is true regarding the mechanisms by which KCC3 accomplishes its numerous functions in animal cells.
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Affiliation(s)
- A P Garneau
- Nephrology Research Group, Department of Medicine, Laval University, Quebec City, Quebec, Canada; and
- Cardiometabolic Axis, Kinesiology Department, University of Montréal, Montreal, Quebec, Canada
| | - A A Marcoux
- Nephrology Research Group, Department of Medicine, Laval University, Quebec City, Quebec, Canada; and
| | - R Frenette-Cotton
- Nephrology Research Group, Department of Medicine, Laval University, Quebec City, Quebec, Canada; and
| | - F Mac-Way
- Nephrology Research Group, Department of Medicine, Laval University, Quebec City, Quebec, Canada; and
| | - J L Lavoie
- Cardiometabolic Axis, Kinesiology Department, University of Montréal, Montreal, Quebec, Canada
| | - P Isenring
- Nephrology Research Group, Department of Medicine, Laval University, Quebec City, Quebec, Canada; and
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21
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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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22
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AlAmri MA, Kadri H, Alderwick LJ, Simpkins NS, Mehellou Y. Rafoxanide and Closantel Inhibit SPAK and OSR1 Kinases by Binding to a Highly Conserved Allosteric Site on Their C-terminal Domains. ChemMedChem 2017; 12:639-645. [PMID: 28371477 DOI: 10.1002/cmdc.201700077] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 03/29/2017] [Indexed: 02/02/2023]
Abstract
SPAK and OSR1 are two protein kinases that have emerged as attractive targets in the discovery of novel antihypertensive agents due to their role in regulating electrolyte balance in vivo. Herein we report the identification of an allosteric pocket on the highly conserved C-terminal domains of these two kinases, which influences their activity. We also show that some known WNK signaling inhibitors bind to this allosteric site. Using in silico screening, we identified the antiparasitic agent rafoxanide as a novel allosteric inhibitor of SPAK and OSR1. Collectively, this work will facilitate the rational design of novel SPAK and OSR1 kinase inhibitors that could be useful antihypertensive agents.
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Affiliation(s)
- Mubarak A AlAmri
- School of Pharmacy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Hachemi Kadri
- School of Pharmacy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Luke J Alderwick
- Birmingham Drug Discovery Facility, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Nigel S Simpkins
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Youcef Mehellou
- School of Pharmacy and Pharmaceutical Sciences, Redwood Building, Cardiff University, Cardiff, CF10 3NB, UK
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23
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Abstract
WNK (With-No-Lysine (K)) kinases are serine-threonine kinases characterized by an atypical placement of a catalytic lysine within the kinase domain. Mutations in human WNK1 or WNK4 cause an autosomal dominant syndrome of hypertension and hyperkalemia, reflecting the fact that WNK kinases are critical regulators of renal ion transport processes. Here, the role of WNKs in the regulation of ion transport processes in vertebrate and invertebrate renal function, cellular and organismal osmoregulation, and cell migration and cerebral edema will be reviewed, along with emerging literature demonstrating roles for WNKs in cardiovascular and neural development, Wnt signaling, and cancer. Conserved roles for these kinases across phyla are emphasized.
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Affiliation(s)
| | - Andreas Jenny
- Albert Einstein College of Medicine, New York, NY, United States.
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24
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Bazúa-Valenti S, Castañeda-Bueno M, Gamba G. Physiological role of SLC12 family members in the kidney. Am J Physiol Renal Physiol 2016; 311:F131-44. [DOI: 10.1152/ajprenal.00071.2016] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 04/12/2016] [Indexed: 12/30/2022] Open
Abstract
The solute carrier family 12, as numbered according to Human Genome Organisation (HUGO) nomenclature, encodes the electroneutral cation-coupled chloride cotransporters that are expressed in many cells and tissues; they play key roles in important physiological events, such as cell volume regulation, modulation of the intracellular chloride concentration, and transepithelial ion transport. Most of these family members are expressed in specific regions of the nephron. The Na-K-2Cl cotransporter NKCC2, which is located in the thick ascending limb, and the Na-Cl cotransporter, which is located in the distal convoluted tubule, play important roles in salt reabsorption and serve as the receptors for loop and thiazide diuretics, respectively (Thiazide diuretics are among the most commonly prescribed drugs in the world.). The activity of these transporters correlates with blood pressure levels; thus, their regulation has been a subject of intense research for more than a decade. The K-Cl cotransporters KCC1, KCC3, and KCC4 are expressed in several nephron segments, and their role in renal physiology is less understood but nevertheless important. Evidence suggests that they are involved in modulating proximal tubule glucose reabsorption, thick ascending limb salt reabsorption and collecting duct proton secretion. In this work, we present an overview of the physiological roles of these transporters in the kidney, with particular emphasis on the knowledge gained in the past few years.
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Affiliation(s)
- Silvana Bazúa-Valenti
- Molecular Physiology Unit, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico
| | - María Castañeda-Bueno
- Molecular Physiology Unit, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico
| | - Gerardo Gamba
- Molecular Physiology Unit, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico
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25
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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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26
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Tang BL. (WNK)ing at death: With-no-lysine (Wnk) kinases in neuropathies and neuronal survival. Brain Res Bull 2016; 125:92-8. [PMID: 27131446 DOI: 10.1016/j.brainresbull.2016.04.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 04/11/2016] [Accepted: 04/24/2016] [Indexed: 12/22/2022]
Abstract
Members of With-no-lysine (WNK) family of serine-threonine kinase are key regulators of chloride ion transport in diverse cell types, controlling the activity and the surface expression of cation-chloride (Na(+)/K(+)-Cl(-)) co-transporters. Mutations in WNK1 and WNK4 are linked to a hereditary form of hypertension, and WNKs have been extensively investigated pertaining to their roles in renal epithelial ion homeostasis. However, some members of the WNK family and their splice isoforms are also expressed in the mammalian brain, and have been implicated in aspects of hereditary neuropathy as well as neuronal and glial survival. WNK2, which is exclusively enriched in neurons, is well known as an anti-proliferative tumor suppressor. WNK3, on the other hand, appears to promote cell survival as its inhibition enhances neuronal apoptosis. However, loss of WNK3 has been recently shown to reduce ischemia-associated brain damage. In this review, I surveyed the potentially context-dependent roles of WNKs in neurological disorders and neuronal survival.
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Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.
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27
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Koumangoye R, Delpire E. The Ste20 kinases SPAK and OSR1 travel between cells through exosomes. Am J Physiol Cell Physiol 2016; 311:C43-53. [PMID: 27122160 DOI: 10.1152/ajpcell.00080.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 04/25/2016] [Indexed: 12/23/2022]
Abstract
Proteomics studies have identified Ste20-related proline/alanine-rich kinase (SPAK) and oxidative stress response 1 (OSR1) in exosomes isolated from body fluids such as blood, saliva, and urine. Because proteomics studies likely overestimate the number of exosome proteins, we sought to confirm and extend this observation using traditional biochemical and cell biology methods. We utilized HEK293 cells in culture to verify the packaging of these Ste20 kinases in exosomes. Using a series of centrifugation and filtration steps of conditioned culture medium isolated from HEK293 cells, we isolated nanovesicles in the range of 40-100 nm. We show that these small vesicles express the tetraspanin protein CD63 and lack endoplasmic reticulum and Golgi markers, consistent with these being exosomes. We show by Western blot and immunogold analyses that these exosomes express SPAK, OSR1, and Na-K-Cl cotransporter 1 (NKCC1). We show that exosomes are not only secreted by cells, but also accumulated by adjacent cells. Indeed, exposing cultured cells to exosomes produced by other cells expressing a fluorescently labeled kinase resulted in the kinase finding its way into the cytoplasm of these cells, consistent with the idea of exosomes serving as cell-to-cell communication vessels. Similarly, coculturing cells expressing different fluorescently tagged proteins resulted in the exchange of proteins between cells. In addition, we show that both SPAK and OSR1 kinases entering cells through exosomes are preferentially expressed at the plasma membrane and that the kinases in exosomes are functional and maintain NKCC1 in a phosphorylated state.
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Affiliation(s)
- Rainelli Koumangoye
- 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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28
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Jentsch TJ. VRACs and other ion channels and transporters in the regulation of cell volume and beyond. Nat Rev Mol Cell Biol 2016; 17:293-307. [PMID: 27033257 DOI: 10.1038/nrm.2016.29] [Citation(s) in RCA: 217] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cells need to regulate their volume to counteract osmotic swelling or shrinkage, as well as during cell division, growth, migration and cell death. Mammalian cells adjust their volume by transporting potassium, sodium, chloride and small organic osmolytes using plasma membrane channels and transporters. This generates osmotic gradients, which drive water in and out of cells. Key players in this process are volume-regulated anion channels (VRACs), the composition of which has recently been identified and shown to encompass LRRC8 heteromers. VRACs also transport metabolites and drugs and function in extracellular signal transduction, apoptosis and anticancer drug resistance.
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Affiliation(s)
- Thomas J Jentsch
- Leibniz-Institut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Robert-Rössle-Strasse 10, 13125 Berlin, Germany
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29
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Bazúa-Valenti S, Gamba G. Revisiting the NaCl cotransporter regulation by with-no-lysine kinases. Am J Physiol Cell Physiol 2015; 308:C779-91. [PMID: 25788573 DOI: 10.1152/ajpcell.00065.2015] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 03/13/2015] [Indexed: 01/26/2023]
Abstract
The renal thiazide-sensitive Na(+)-Cl(-) cotransporter (NCC) is the salt transporter in the distal convoluted tubule. Its activity is fundamental for defining blood pressure levels. Decreased NCC activity is associated with salt-remediable arterial hypotension with hypokalemia (Gitelman disease), while increased activity results in salt-sensitive arterial hypertension with hyperkalemia (pseudohypoaldosteronism type II; PHAII). The discovery of four different genes causing PHAII revealed a complex multiprotein system that regulates the activity of NCC. Two genes encode for with-no-lysine (K) kinases WNK1 and WNK4, while two encode for kelch-like 3 (KLHL3) and cullin 3 (CUL3) proteins that form a RING type E3 ubiquitin ligase complex. Extensive research has shown that WNK1 and WNK4 are the targets for the KLHL3-CUL3 complex and that WNKs modulate the activity of NCC by means of intermediary Ste20-type kinases known as SPAK or OSR1. The understanding of the effect of WNKs on NCC is a complex issue, but recent evidence discussed in this review suggests that we could be reaching the end of the dark ages regarding this matter.
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Affiliation(s)
- Silvana Bazúa-Valenti
- Molecular Physiology Unit, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Gerardo Gamba
- Molecular Physiology Unit, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
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30
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Hartmann AM, Nothwang HG. Molecular and evolutionary insights into the structural organization of cation chloride cotransporters. Front Cell Neurosci 2015; 8:470. [PMID: 25653592 PMCID: PMC4301019 DOI: 10.3389/fncel.2014.00470] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/30/2014] [Indexed: 01/26/2023] Open
Abstract
Cation chloride cotransporters (CCC) play an essential role for neuronal chloride homeostasis. K(+)-Cl(-) cotransporter (KCC2), is the principal Cl(-)-extruder, whereas Na(+)-K(+)-Cl(-) cotransporter (NKCC1), is the major Cl(-)-uptake mechanism in many neurons. As a consequence, the action of the inhibitory neurotransmitters gamma-aminobutyric acid (GABA) and glycine strongly depend on the activity of these two transporters. Knowledge of the mechanisms involved in ion transport and regulation is thus of great importance to better understand normal and disturbed brain function. Although no overall 3-dimensional crystal structures are yet available, recent molecular and phylogenetic studies and modeling have provided new and exciting insights into structure-function relationships of CCC. Here, we will summarize our current knowledge of the gross structural organization of the proteins, their functional domains, ion binding and translocation sites, and the established role of individual amino acids (aa). A major focus will be laid on the delineation of shared and distinct organizational principles between KCC2 and NKCC1. Exploiting the richness of recently generated genome data across the tree of life, we will also explore the molecular evolution of these features.
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Affiliation(s)
- Anna-Maria Hartmann
- Systematics and Evolutionary Biology Group, Institute for Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg Oldenburg, Germany
| | - Hans Gerd Nothwang
- Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg Oldenburg, Germany ; Research Center for Neurosensory Sciences, Carl von Ossietzky University Oldenburg Oldenburg, Germany
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31
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Alessi DR, Zhang J, Khanna A, Hochdörfer T, Shang Y, Kahle KT. The WNK-SPAK/OSR1 pathway: master regulator of cation-chloride cotransporters. Sci Signal 2014; 7:re3. [PMID: 25028718 DOI: 10.1126/scisignal.2005365] [Citation(s) in RCA: 189] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The WNK-SPAK/OSR1 kinase complex is composed of the kinases WNK (with no lysine) and SPAK (SPS1-related proline/alanine-rich kinase) or the SPAK homolog OSR1 (oxidative stress-responsive kinase 1). The WNK family senses changes in intracellular Cl(-) concentration, extracellular osmolarity, and cell volume and transduces this information to sodium (Na(+)), potassium (K(+)), and chloride (Cl(-)) cotransporters [collectively referred to as CCCs (cation-chloride cotransporters)] and ion channels to maintain cellular and organismal homeostasis and affect cellular morphology and behavior. Several genes encoding proteins in this pathway are mutated in human disease, and the cotransporters are targets of commonly used drugs. WNKs stimulate the kinases SPAK and OSR1, which directly phosphorylate and stimulate Cl(-)-importing, Na(+)-driven CCCs or inhibit the Cl(-)-extruding, K(+)-driven CCCs. These coordinated and reciprocal actions on the CCCs are triggered by an interaction between RFXV/I motifs within the WNKs and CCCs and a conserved carboxyl-terminal docking domain in SPAK and OSR1. This interaction site represents a potentially druggable node that could be more effective than targeting the cotransporters directly. In the kidney, WNK-SPAK/OSR1 inhibition decreases epithelial NaCl reabsorption and K(+) secretion to lower blood pressure while maintaining serum K(+). In neurons, WNK-SPAK/OSR1 inhibition could facilitate Cl(-) extrusion and promote γ-aminobutyric acidergic (GABAergic) inhibition. Such drugs could have efficacy as K(+)-sparing blood pressure-lowering agents in essential hypertension, nonaddictive analgesics in neuropathic pain, and promoters of GABAergic inhibition in diseases associated with neuronal hyperactivity, such as epilepsy, spasticity, neuropathic pain, schizophrenia, and autism.
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Affiliation(s)
- Dario R Alessi
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - Jinwei Zhang
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - Arjun Khanna
- Department of Neurosurgery, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02115, USA
| | - Thomas Hochdörfer
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland
| | - Yuze Shang
- Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA
| | - Kristopher T Kahle
- Department of Neurosurgery, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02115, USA. Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA.
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Weber M, Hartmann AM, Beyer T, Ripperger A, Nothwang HG. A novel regulatory locus of phosphorylation in the C terminus of the potassium chloride cotransporter KCC2 that interferes with N-ethylmaleimide or staurosporine-mediated activation. J Biol Chem 2014; 289:18668-79. [PMID: 24849604 PMCID: PMC4081912 DOI: 10.1074/jbc.m114.567834] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/15/2014] [Indexed: 11/06/2022] Open
Abstract
The neuron-specific cation chloride cotransporter KCC2 plays a crucial role in hyperpolarizing synaptic inhibition. Transporter dysfunction is associated with various neurological disorders, raising interest in regulatory mechanisms. Phosphorylation has been identified as a key regulatory process. Here, we retrieved experimentally observed phosphorylation sites of KCC2 from public databases and report on the systematic analysis of six phosphorylated serines, Ser(25), Ser(26), Ser(937), Ser(1022), Ser(1025), and Ser(1026). Alanine or aspartate substitutions of these residues were analyzed in HEK-293 cells. All mutants were expressed in a pattern similar to wild-type KCC2 (KCC2(WT)). Tl(+) flux measurements demonstrated unchanged transport activity for Ser(25), Ser(26), Ser(1022), Ser(1025), and Ser(1026) mutants. In contrast, KCC2(S937D), mimicking phosphorylation, resulted in a significant up-regulation of transport activity. Aspartate substitution of Thr(934), a neighboring putative phosphorylation site, resulted in a comparable increase in KCC2 transport activity. Both KCC2(T934D) and KCC2(S937D) mutants were inhibited by the kinase inhibitor staurosporine and by N-ethylmaleimide, whereas KCC2(WT), KCC2(T934A), and KCC2(S937A) were activated. The inverse staurosporine effect on aspartate versus alanine substitutions reveals a cross-talk between different phosphorylation sites of KCC2. Immunoblot and cell surface labeling experiments detected no alterations in total abundance or surface expression of KCC2(T934D) and KCC2(S937D) compared with KCC2(WT). These data reveal kinetic regulation of transport activity by these residues. In summary, our data identify a novel key regulatory phosphorylation site of KCC2 and a functional interaction between different conformation-changing post-translational modifications. The action of pharmacological agents aimed to modulate KCC2 activity for therapeutic benefit might therefore be highly context-specific.
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Affiliation(s)
- Maren Weber
- From the Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences
| | - Anna-Maria Hartmann
- From the Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Systematics and Evolutionary Biology Group, Institute for Biology and Environmental Sciences, and
| | - Timo Beyer
- From the Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences
| | - Anne Ripperger
- From the Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences
| | - Hans Gerd Nothwang
- From the Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, the Research Center for Neurosensory Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
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delos Heros P, Alessi D, Gourlay R, Campbell D, Deak M, Macartney T, Kahle K, Zhang J. The WNK-regulated SPAK/OSR1 kinases directly phosphorylate and inhibit the K+-Cl- co-transporters. Biochem J 2014; 458:559-73. [PMID: 24393035 PMCID: PMC3940040 DOI: 10.1042/bj20131478] [Citation(s) in RCA: 156] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Precise homoeostasis of the intracellular concentration of Cl- is achieved via the co-ordinated activities of the Cl- influx and efflux. We demonstrate that the WNK (WNK lysine-deficient protein kinase)-activated SPAK (SPS1-related proline/alanine-rich kinase)/OSR1 (oxidative stress-responsive kinase 1) known to directly phosphorylate and stimulate the N[K]CCs (Na+-K+ ion co-transporters), also promote inhibition of the KCCs (K+-Cl- co-transporters) by directly phosphorylating a recently described C-terminal threonine residue conserved in all KCC isoforms [Site-2 (Thr1048)]. First, we demonstrate that SPAK and OSR1, in the presence of the MO25 regulatory subunit, robustly phosphorylates all KCC isoforms at Site-2 in vitro. Secondly, STOCK1S-50699, a WNK pathway inhibitor, suppresses SPAK/OSR1 activation and KCC3A Site-2 phosphorylation with similar efficiency. Thirdly, in ES (embryonic stem) cells lacking SPAK/OSR1 activity, endogenous phosphorylation of KCC isoforms at Site-2 is abolished and these cells display elevated basal activity of 86Rb+ uptake that was not markedly stimulated further by hypotonic high K+ conditions, consistent with KCC3A activation. Fourthly, a tight correlation exists between SPAK/OSR1 activity and the magnitude of KCC3A Site-2 phosphorylation. Lastly, a Site-2 alanine KCC3A mutant preventing SPAK/OSR1 phosphorylation exhibits increased activity. We also observe that KCCs are directly phosphorylated by SPAK/OSR1, at a novel Site-3 (Thr5 in KCC1/KCC3 and Thr6 in KCC2/KCC4), and a previously recognized KCC3-specific residue, Site-4 (Ser96). These data demonstrate that the WNK-regulated SPAK/OSR1 kinases directly phosphorylate the N[K]CCs and KCCs, promoting their stimulation and inhibition respectively. Given these reciprocal actions with anticipated net effects of increasing Cl- influx, we propose that the targeting of WNK-SPAK/OSR1 with kinase inhibitors might be a novel potent strategy to enhance cellular Cl- extrusion, with potential implications for the therapeutic modulation of epithelial and neuronal ion transport in human disease states.
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Key Words
- γ-aminobutyric acid (gaba)
- blood pressure/hypertension
- ion homoeostasis
- k+–cl− co-transporter 2 (kcc2)
- k+–cl− co-transporter 3 (kcc3)
- na+–cl− co-transporter (ncc)
- na+–k+–2cl− co-transporter 1 (nkcc1)
- protein kinase
- signal transduction
- ccc, cation–cl− co-transporter
- cct, conserved c-terminal
- ctd, c-terminal cytoplasmic domain
- erk1, extracellular-signal-regulated kinase 1
- es, embryonic stem
- hek, human embryonic kidney
- hrp, horseradish peroxidase
- kcc, k+–cl− co-transporter
- lds, lithium dodecyl sulfate
- ncc, na+–cl− co-transporter
- n[k]cc, na+–k+ ion co-transporter
- nkcc, na+–k+–2cl− co-transporter
- ntd, n-terminal cytoplasmic domain
- osr1, oxidative stress-responsive kinase 1
- slc12, solute carrier family 12
- spak, sps1-related proline/alanine-rich kinase
- ttbs, tris-buffered saline containing tween 20
- wnk, wnk lysine-deficient protein kinase
- xic, extracted ion chromatogram
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Affiliation(s)
- Paola delos Heros
- *MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
| | - Dario R. Alessi
- *MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
- 1Correspondence may be addressed to either of these authors (email or )
| | - Robert Gourlay
- *MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
| | - David G. Campbell
- *MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
| | - Maria Deak
- *MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
| | - Thomas J. Macartney
- *MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
| | - Kristopher T. Kahle
- †Department of Neurosurgery, Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, U.S.A
- ‡Manton Center for Orphan Disease Research, Children's Hospital Boston, Boston, MA 02115, U.S.A
| | - Jinwei Zhang
- *MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, U.K
- 1Correspondence may be addressed to either of these authors (email or )
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