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Maraschi AC, Faria SC, McNamara JC. Salt transport by the gill Na -K -2Cl symporter in palaemonid shrimps: exploring physiological, molecular and evolutionary landscapes. Comp Biochem Physiol A Mol Integr Physiol 2021; 257:110968. [DOI: 10.1016/j.cbpa.2021.110968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/21/2021] [Accepted: 04/21/2021] [Indexed: 12/22/2022]
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Zhang J, Cordshagen A, Medina I, Nothwang HG, Wisniewski JR, Winklhofer M, Hartmann AM. Staurosporine and NEM mainly impair WNK-SPAK/OSR1 mediated phosphorylation of KCC2 and NKCC1. PLoS One 2020; 15:e0232967. [PMID: 32413057 PMCID: PMC7228128 DOI: 10.1371/journal.pone.0232967] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 04/24/2020] [Indexed: 02/05/2023] Open
Abstract
The pivotal role of KCC2 and NKCC1 in development and maintenance of fast inhibitory neurotransmission and their implication in severe human diseases arouse interest in posttranscriptional regulatory mechanisms such as (de)phosphorylation. Staurosporine (broad kinase inhibitor) and N-ethylmalemide (NEM) that modulate kinase and phosphatase activities enhance KCC2 and decrease NKCC1 activity. Here, we investigated the regulatory mechanism for this reciprocal regulation by mass spectrometry and immunoblot analyses using phospho-specific antibodies. Our analyses revealed that application of staurosporine or NEM dephosphorylates Thr1007 of KCC2, and Thr203, Thr207 and Thr212 of NKCC1. Dephosphorylation of Thr1007 of KCC2, and Thr207 and Thr212 of NKCC1 were previously demonstrated to activate KCC2 and to inactivate NKCC1. In addition, application of the two agents resulted in dephosphorylation of the T-loop and S-loop phosphorylation sites Thr233 and Ser373 of SPAK, a critical kinase in the WNK-SPAK/OSR1 signaling module mediating phosphorylation of KCC2 and NKCC1. Taken together, these results suggest that reciprocal regulation of KCC2 and NKCC1 via staurosporine and NEM is based on WNK-SPAK/OSR1 signaling. The key regulatory phospho-site Ser940 of KCC2 is not critically involved in the enhanced activation of KCC2 upon staurosporine and NEM treatment, as both agents have opposite effects on its phosphorylation status. Finally, NEM acts in a tissue-specific manner on Ser940, as shown by comparative analysis in HEK293 cells and immature cultured hippocampal neurons. In summary, our analyses identified phospho-sites that are responsive to staurosporine or NEM application. This provides important information towards a better understanding of the cooperative interactions of different phospho-sites.
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Affiliation(s)
- Jinwei Zhang
- Hatherly Laboratories, Medical School, College of Medicine and Health, Institute of Biomedical and Clinical Sciences, University of Exeter, Exeter, United Kingdom
- Xiamen Cardiovascular Hospital, School of Medicine, Xiamen University, Xiamen, China
| | - Antje Cordshagen
- Division of Neurogenetics, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Igor Medina
- INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 1249, INMED (Institut de Neurobiologie de la Méditerranée), Aix-Marseille University UMR 1249, Marseille, France
| | - Hans Gerd Nothwang
- Division of Neurogenetics, 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
- Center of Excellence Hearing4all, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Jacek R. Wisniewski
- Department of Proteomics and Signal Transduction, Biochemical Proteomics Group, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Michael Winklhofer
- Research Center for Neurosensory Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
- Institute for Biology and Environmental Sciences IBU, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Anna-Maria Hartmann
- Division of Neurogenetics, 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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Shaughnessy CA, McCormick SD. Functional characterization and osmoregulatory role of the Na +-K +-2Cl - cotransporter in the gill of sea lamprey ( Petromyzon marinus), a basal vertebrate. Am J Physiol Regul Integr Comp Physiol 2019; 318:R17-R29. [PMID: 31617750 DOI: 10.1152/ajpregu.00125.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study provides molecular and functional characterization of Na+-K+-2Cl- cotransporter (NKCC1/Slc12a2) in the gills of sea lamprey (Petromyzon marinus), the most basal extant vertebrate with an osmoregulatory strategy. We report the full-length peptide sequence for the lamprey Na-K-Cl cotransporter 1 (NKCC1), which we show groups strongly with and occupies a basal position among other vertebrate NKCC1 sequences. In postmetamorphic juvenile lamprey, nkcc1 mRNA was present in many tissues but was fivefold higher in the gill than any other examined tissue, and NKCC1 protein was only detected in the gill. Gill mRNA and protein abundances of NKCC1 and Na+-K+-ATPase (NKA/Atp1a1) were significantly upregulated (20- to 200-fold) during late metamorphosis in fresh water, coinciding with the development of salinity tolerance, and were upregulated an additional twofold after acclimation to seawater (SW). Immunohistochemistry revealed that NKCC1 in the gill is found in filamental ionocytes coexpressing NKA, which develop during metamorphosis in preparation for SW entry. Lamprey treated with bumetanide, a widely used pharmacological inhibitor of NKCC1, exhibited higher plasma Cl- and osmolality as well as reduced muscle water content after 24 h in SW; there were no effects of bumetanide in freshwater-acclimated lamprey. This work provides the first functional characterization of NKCC1 as a mechanism for branchial salt secretion in lampreys, providing evidence that this mode of Cl- secretion has been present among vertebrates for ~550 million years.
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Affiliation(s)
- Ciaran A Shaughnessy
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, Massachusetts
| | - Stephen D McCormick
- United States.Geological Survey, Leetown Science Center, Conte Anadromous Fish Research Laboratory, Turners Falls, Massachusetts.,Department of Biology, University of Massachusetts, Amherst, Massachusetts
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Gregório SF, Ruiz-Jarabo I, Carvalho EM, Fuentes J. Increased intestinal carbonate precipitate abundance in the sea bream (Sparus aurata L.) in response to ocean acidification. PLoS One 2019; 14:e0218473. [PMID: 31226164 PMCID: PMC6588277 DOI: 10.1371/journal.pone.0218473] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/03/2019] [Indexed: 12/20/2022] Open
Abstract
Marine fish contribute to the carbon cycle by producing mineralized intestinal precipitates generated as by-products of their osmoregulation. Here we aimed at characterizing the control of epithelial bicarbonate secretion and intestinal precipitate presence in the gilthead sea bream in response to predicted near future increases of environmental CO2. Our results demonstrate that hypercapnia (950 and 1800 μatm CO2) elicits higher intestine epithelial HCO3- secretion ex vivo and a subsequent parallel increase of intestinal precipitate presence in vivo when compared to present values (440 μatm CO2). Intestinal gene expression analysis in response to environmental hypercapnia revealed the up-regulation of transporters involved in the intestinal bicarbonate secretion cascade such as the basolateral sodium bicarbonate co-transporter slc4a4, and the apical anion transporters slc26a3 and slc26a6 of sea bream. In addition, other genes involved in intestinal ion uptake linked to water absorption such as the apical nkcc2 and aquaporin 1b expression, indicating that hypercapnia influences different levels of intestinal physiology. Taken together the current results are consistent with an intestinal physiological response leading to higher bicarbonate secretion in the intestine of the sea bream paralleled by increased luminal carbonate precipitate abundance and the main related transporters in response to ocean acidification.
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Affiliation(s)
- Sílvia F. Gregório
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Ignacio Ruiz-Jarabo
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Edison M. Carvalho
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Juan Fuentes
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
- * E-mail:
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Shahidullah M, Mandal A, Delamere NA. Activation of TRPV1 channels leads to stimulation of NKCC1 cotransport in the lens. Am J Physiol Cell Physiol 2018; 315:C793-C802. [PMID: 30207782 DOI: 10.1152/ajpcell.00252.2018] [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] [Indexed: 11/22/2022]
Abstract
Lens ion homeostasis is crucial in maintaining water content and, in turn, refractive index and transparency of the multicellular syncytium-like structure. New information is emerging on the regulation of ion transport in the lens by mechanisms that rely on transient receptor potential vanilloid (TRPV) ion channels. We found recently that TRPV1 activation leads to Ca2+/PKC-dependent ERK1/2 signaling. Here, we show that the TRPV1 agonist capsaicin (100 nM) and hyperosmotic solution (350 vs. 300 mosM) each caused an increase of bumetanide-inhibitable Rb uptake by intact porcine lenses and Na-K-2Cl cotransporter 1 (NKCC1) phosphorylation in the lens epithelium. The TRPV1 antagonist A889425 (1 µM) abolished the increases of Rb uptake and NKCC1 phosphorylation in response to hyperosmotic solution. Exposing lenses to hyperosmotic solution in the presence of MEK/ERK inhibitor U0126 (10 µM) or the with-no-lysine kinase (WNK) inhibitor WNK463 (1 µM) also prevented NKCC1 phosphorylation and the Rb uptake responses to hyperosmotic solution. WNK463 did not prevent the increase in ERK1/2 phosphorylation that occurs in response to capsaicin or hyperosmotic solution, suggesting that ERK1/2 activation occurs before WNK activation in the sequence of signaling events. Taken together, the evidence indicates that activation of TRPV1 is a critical early step in a signaling mechanism that responds to a hyperosmotic stimulus, possibly lens shrinkage. By activating ERK1/2 and WNK, TRPV1 activation leads to NKCC1 phosphorylation and stimulation of NKCC1-mediated ion transport.
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Affiliation(s)
- Mohammad Shahidullah
- Department of Physiology, University of Arizona , Tucson, Arizona.,Department of Ophthalmology and Vision Science, University of Arizona , Tucson, Arizona
| | - Amritlal Mandal
- Department of Physiology, University of Arizona , Tucson, Arizona
| | - Nicholas A Delamere
- Department of Physiology, University of Arizona , Tucson, Arizona.,Department of Ophthalmology and Vision Science, University of Arizona , Tucson, Arizona
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Genomic signatures of parasite-driven natural selection in north European Atlantic salmon (Salmo salar). Mar Genomics 2018; 39:26-38. [DOI: 10.1016/j.margen.2018.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 12/16/2017] [Accepted: 01/08/2018] [Indexed: 02/06/2023]
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Flatt JF, Bruce LJ. The Molecular Basis for Altered Cation Permeability in Hereditary Stomatocytic Human Red Blood Cells. Front Physiol 2018; 9:367. [PMID: 29713289 PMCID: PMC5911802 DOI: 10.3389/fphys.2018.00367] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 03/27/2018] [Indexed: 11/20/2022] Open
Abstract
Normal human RBCs have a very low basal permeability (leak) to cations, which is continuously corrected by the Na,K-ATPase. The leak is temperature-dependent, and this temperature dependence has been evaluated in the presence of inhibitors to exclude the activity of the Na,K-ATPase and NaK2Cl transporter. The severity of the RBC cation leak is altered in various conditions, most notably the hereditary stomatocytosis group of conditions. Pedigrees within this group have been classified into distinct phenotypes according to various factors, including the severity and temperature-dependence of the cation leak. As recent breakthroughs have provided more information regarding the molecular basis of hereditary stomatocytosis, it has become clear that these phenotypes elegantly segregate with distinct genetic backgrounds. The cryohydrocytosis phenotype, including South-east Asian Ovalocytosis, results from mutations in SLC4A1, and the very rare condition, stomatin-deficient cryohydrocytosis, is caused by mutations in SLC2A1. Mutations in RHAG cause the very leaky condition over-hydrated stomatocytosis, and mutations in ABCB6 result in familial pseudohyperkalemia. All of the above are large multi-spanning membrane proteins and the mutations may either modify the structure of these proteins, resulting in formation of a cation pore, or otherwise disrupt the membrane to allow unregulated cation movement across the membrane. More recently mutations have been found in two RBC cation channels, PIEZO1 and KCNN4, which result in dehydrated stomatocytosis. These mutations alter the activation and deactivation kinetics of these channels, leading to increased opening and allowing greater cation fluxes than in wild type.
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Affiliation(s)
- Joanna F Flatt
- Bristol Institute for Transfusion Sciences, NHS Blood and Transplant, Bristol, United Kingdom
| | - Lesley J Bruce
- Bristol Institute for Transfusion Sciences, NHS Blood and Transplant, Bristol, United Kingdom
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The modulation of the phosphorylation status of NKCC1 in organ cultured bovine lenses: Implications for the regulation of fiber cell and overall lens volume. Exp Eye Res 2017; 165:164-174. [PMID: 28818393 DOI: 10.1016/j.exer.2017.08.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 07/25/2017] [Accepted: 08/11/2017] [Indexed: 11/24/2022]
Abstract
In previous work, we have shown the Sodium/Potassium/2 Chloride Cotransporter (NKCC1) to be a key effector of lens fiber cell volume regulation. Since others have shown that the activity of NKCC1 is regulated via its phosphorylation status, the purpose of this study was to investigate whether NKCC1 phosphorylation can be modulated in organ cultured bovine lenses, and to see how this relates to changes in lens wet weight. Western blotting was first used to confirm the expression of NKCC1, phosphorylated NKCC1 (NKCC1-P) and the regulatory kinases WNK/SPAK and phosphatases PP1/PP2A in bovine lenses at the protein level. Changes to NKCC1-P status were then assessed by organ culturing bovine lenses in either isotonic, hypertonic or hypotonic solutions in the presence or absence of the NKCC inhibitor, bumetanide, or phosphatase inhibitors okadaic acid and calyculin A. After 1-22 h of culturing, lenses were weighed, assessed for transparency and the cortical protein fractions analyzed by western blot using antibodies to detect total NKCC1 and NKCC1-P. NKCC1, NKCC1-P, SPAK, PP1 and PP2A were all detected in the membrane fraction of bovine lenses. Under hypertonic conditions, NKCC1 is phosphorylated and activated to mediate a regulatory volume increase. Finally, NKCC1-P signal increased in the presence of phosphatase inhibitors indicating that PP1/PP2A can dephosphorylate NKCC1. These results show that the phosphorylation status and hence activity of NKCC1 is dynamically regulated and that in response to hypertonic stress, NKCC1 activity is increased to effect a regulatory volume increase that limits cell shrinkage. These findings support the view that the lens dynamically regulates ion fluxes to maintain steady state lens volume, and suggest that dysfunction of this regulation maybe an initiating factor in the localized fiber cell swelling that is a characteristic of diabetic lens cataract.
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Komoroske LM, Jeffries KM, Connon RE, Dexter J, Hasenbein M, Verhille C, Fangue NA. Sublethal salinity stress contributes to habitat limitation in an endangered estuarine fish. Evol Appl 2016; 9:963-81. [PMID: 27606005 PMCID: PMC4999527 DOI: 10.1111/eva.12385] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Accepted: 04/11/2016] [Indexed: 01/13/2023] Open
Abstract
As global change alters multiple environmental conditions, predicting species' responses can be challenging without understanding how each environmental factor influences organismal performance. Approaches quantifying mechanistic relationships can greatly complement correlative field data, strengthening our abilities to forecast global change impacts. Substantial salinity increases are projected in the San Francisco Estuary, California, due to anthropogenic water diversion and climatic changes, where the critically endangered delta smelt (Hypomesus transpacificus) largely occurs in a low-salinity zone (LSZ), despite their ability to tolerate a much broader salinity range. In this study, we combined molecular and organismal measures to quantify the physiological mechanisms and sublethal responses involved in coping with salinity changes. Delta smelt utilize a suite of conserved molecular mechanisms to rapidly adjust their osmoregulatory physiology in response to salinity changes in estuarine environments. However, these responses can be energetically expensive, and delta smelt body condition was reduced at high salinities. Thus, acclimating to salinities outside the LSZ could impose energetic costs that constrain delta smelt's ability to exploit these habitats. By integrating data across biological levels, we provide key insight into the mechanistic relationships contributing to phenotypic plasticity and distribution limitations and advance the understanding of the molecular osmoregulatory responses in nonmodel estuarine fishes.
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Affiliation(s)
- Lisa M. Komoroske
- Department of Wildlife, Fish & Conservation BiologyUniversity of California at DavisDavisCAUSA
- Department of Anatomy, Physiology & Cell BiologySchool of Veterinary MedicineUniversity of California at DavisDavisCAUSA
- National Research Council under contract to Southwest Fisheries Science Center, National Marine Fisheries ServiceNational Oceanic and Atmospheric AdministrationLa JollaCAUSA
| | - Ken M. Jeffries
- Department of Wildlife, Fish & Conservation BiologyUniversity of California at DavisDavisCAUSA
- Department of Anatomy, Physiology & Cell BiologySchool of Veterinary MedicineUniversity of California at DavisDavisCAUSA
| | - Richard E. Connon
- Department of Anatomy, Physiology & Cell BiologySchool of Veterinary MedicineUniversity of California at DavisDavisCAUSA
| | - Jason Dexter
- Department of Wildlife, Fish & Conservation BiologyUniversity of California at DavisDavisCAUSA
| | - Matthias Hasenbein
- Department of Wildlife, Fish & Conservation BiologyUniversity of California at DavisDavisCAUSA
- Department of Anatomy, Physiology & Cell BiologySchool of Veterinary MedicineUniversity of California at DavisDavisCAUSA
| | - Christine Verhille
- Department of Wildlife, Fish & Conservation BiologyUniversity of California at DavisDavisCAUSA
| | - Nann A. Fangue
- Department of Wildlife, Fish & Conservation BiologyUniversity of California at DavisDavisCAUSA
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Xue H, Tang X. Effect of vasopressin on Na(+)-K(+)-2Cl(-) cotransporter (NKCC) and the signaling mechanisms on the murine late distal colon. Eur J Pharmacol 2015; 771:241-6. [PMID: 26656758 DOI: 10.1016/j.ejphar.2015.11.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 11/24/2015] [Accepted: 11/27/2015] [Indexed: 11/15/2022]
Abstract
It has been demonstrated that the antidiuretic hormone vasopressin is able to regulate the expression of Na-K-Cl cotransporters (NKCC1 and NKCC2) in the kidney. The present study investigated the effects of long- and short-term administration of vasopressin on NKCC and the possible signaling mechanism of vasopressin in the mouse distal colon using the siRNA, real-time PCR, western blotting and Ussing chambers method. The results showed the presence of NKCC2 expression in the colon, which was verified with a siRNA technique. The mRNA and protein expression level of NKCC2 significantly increased by about 40% and 90% respectively in response to restricting water intake to 1ml/day/20g for 7 days. In contrast, the NKCC1 expression level was unchanged in the colon. To determine the short-term activation of NKCC2 by vasopressin in vitro, we found that the administration of vasopressin caused a 3-fold increase in mouse colon NKCC2 phosphorylation, which was detected with phosphospecific antibody R5. In addition, the Ussing chamber results showed that NKCC2, cAMP and Ca(2+) signaling pathway may be involved in the vasopressin-induced response. Further, adenylate cyclase inhibitor MDL-12330A and PKA inhibitor H89 and Ca(2+) chelator BAPTA-AM reversed the vasopressin induced NKCC2 phosphorylation level increase by about 35%, 28% and 42% respectively suggesting vasopressin stimulate NKCC2 phosphorylation increase mediated by cAMP-PKA and Ca(2+) signaling in the colon. Collectively, these data suggest that the expression and phosphorylation of NKCC2 are increased in the colon by vasopressin stimulation, in association with enhanced activity of the vasopressin/cAMP and Ca(2+) pathways.
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Affiliation(s)
- Hong Xue
- Digestive Laboratory of Traditional Chinese Medicine Research Institute of spleen and stomach diseases, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China; Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Xudong Tang
- Digestive Laboratory of Traditional Chinese Medicine Research Institute of spleen and stomach diseases, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China.
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Sullivan CR, Funk AJ, Shan D, Haroutunian V, McCullumsmith RE. Decreased chloride channel expression in the dorsolateral prefrontal cortex in schizophrenia. PLoS One 2015; 10:e0123158. [PMID: 25826365 PMCID: PMC4380350 DOI: 10.1371/journal.pone.0123158] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 02/17/2015] [Indexed: 12/17/2022] Open
Abstract
Alterations in GABAergic neurotransmission are implicated in several psychiatric illnesses, including schizophrenia. The Na-K-Cl and K-Cl cotransporters regulate intracellular chloride levels. Abnormalities in cotransporter expression levels could shift the chloride electrochemical gradient and impair GABAergic transmission. In this study, we performed Western blot analysis to investigate whether the Na-K-Cl and K-Cl cotransporter protein is abnormally expressed in the dorsal lateral prefrontal cortex and the anterior cingulate cortex in patients with schizophrenia versus a control group. We found decreased K-Cl cotransporter protein expression in the dorsal lateral prefrontal cortex, but not the anterior cingulate cortex, in subjects with schizophrenia, supporting the hypothesis of region level abnormal GABAergic function in the pathophysiology of schizophrenia. Subjects with schizophrenia off antipsychotic medication at the time of death had decreased K-Cl cotransporter protein expression compared to both normal controls and subjects with schizophrenia on antipsychotics. Our results provide evidence for KCC2 protein abnormalities in schizophrenia and suggest that antipsychotic medications might reverse deficits of this protein in the illness.
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Affiliation(s)
- Courtney R. Sullivan
- University of Cincinnati College of Medicine, Neuroscience Graduate Program, Cincinnati, Ohio, United States of America
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Adam J. Funk
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Dan Shan
- Department of Nephrology, University of Alabama Birmingham, Birmingham, Alabama, United States of America
| | - Vahram Haroutunian
- Department of Psychiatry, Mount Sinai School of Medicine, New York, New York, United States of America
- James J Peters Veterans Affairs Medical Center, New York, New York, United States of America
| | - Robert E. McCullumsmith
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, Ohio, United States of America
- * E-mail:
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Emerging role of WNK1 in pathologic central nervous system signaling. Ann Neurosci 2014; 18:70-5. [PMID: 25205925 PMCID: PMC4117038 DOI: 10.5214/ans.0972.7531.1118212] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 03/30/2011] [Accepted: 04/21/2011] [Indexed: 01/28/2023] Open
Abstract
WNK1 (with no lysine (K)) is a widely expressed serine/threonine protein kinase. The role of this kinase was first described in the kidney where it dynamically controls ion channels that regulate changes in cell volume. WNK1, through intermediates oxidative stress-responsive kinase-1 (OSR1) and STE20/SPS1-related proline/alanine-rich kinase (SPAK), phosphorylates the inwardly directed Na+-K+-Cl---cotransporter 1 (NKCC1) and the outwardly directed K+-Cl--cotransporter 2 (KCC2), activating and deactivating these channels, respectively. WNK1, NKCC1 and KCC2 are also expressed in the central nervous system (CNS). Growing evidence implicates WNK1 playing a critical role in pathologic nervous system signaling where changes in intracellular ion concentration in response to γ-aminobutyric-acid (GABA) can activate otherwise silent pathways. This review will focus on current research about WNK1, its downstream effectors and role in GABA signaling. Future perspectives include investigating WNK1 expression in the CNS after spinal cord injury (SCI), where altered neuronal signaling could underlie pathological states such as neuropathic pain (NP).
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Comparative transcriptional profiling of two wheat genotypes, with contrasting levels of minerals in grains, shows expression differences during grain filling. PLoS One 2014; 9:e111718. [PMID: 25364903 PMCID: PMC4218811 DOI: 10.1371/journal.pone.0111718] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 10/03/2014] [Indexed: 12/24/2022] Open
Abstract
Wheat is one of the most important cereal crops in the world. To identify the candidate genes for mineral accumulation, it is important to examine differential transcriptome between wheat genotypes, with contrasting levels of minerals in grains. A transcriptional comparison of developing grains was carried out between two wheat genotypes- Triticum aestivum Cv. WL711 (low grain mineral), and T. aestivum L. IITR26 (high grain mineral), using Affymetrix GeneChip Wheat Genome Array. The study identified a total of 580 probe sets as differentially expressed (with log2 fold change of ≥2 at p≤0.01) between the two genotypes, during grain filling. Transcripts with significant differences in induction or repression between the two genotypes included genes related to metal homeostasis, metal tolerance, lignin and flavonoid biosynthesis, amino acid and protein transport, vacuolar-sorting receptor, aquaporins, and stress responses. Meta-analysis revealed spatial and temporal signatures of a majority of the differentially regulated transcripts.
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Xue H, Zhang ZJ, Li XS, Sun HM, Kang Q, Wu B, Wang YX, Zou WJ, Zhou DS. Localization and vasopressin regulation of the Na +-K +-2Cl - cotransporter in the distal colonic epithelium. World J Gastroenterol 2014; 20:4692-4701. [PMID: 24782621 PMCID: PMC4000505 DOI: 10.3748/wjg.v20.i16.4692] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 02/09/2014] [Accepted: 03/05/2014] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate whether Na+-K+-2Cl- cotransporter (NKCC2) is expressed in the mouse distal colonic epithelia and whether it is regulated by vasopressin in the colon.
METHODS: The mRNA expression of NKCC2 in the mouse colonic mucosa was examined by reverse transcription-polymerase chain reaction. NKCC trafficking in the colon stimulated by 1-D-amino(8-D-arginine)-vasopressin (dDAVP) infusion (10 ng/mouse, intraperitoneal injection ) within 15 min, 30 min and 1h was investigated by laser confocal scanning microscopy. Total and membrane NKCC2 expression in the colonic mucosa from control and dDAVP-treated mice was detected by Western blotting. Short circuit current method was performed to determine regulation of NKCC2 by vasopressin in the colon.
RESULTS: NKCC2 was predominantly located in the apical region of the surface of the distal colonic epithelia; by comparison, a large amount of NKCC1 was distributed in the basolateral membrane of the lower crypt epithelia of the mouse distal colon. Short-term treatment with dDAVP, a V2-type receptor-specific vasopressin analog, induced NKCC2 re-distribution, i.e., NKCC2 traffics to the apical membrane after dDAVP stimulation. In contrast, no obvious NKCC1 membrane translocation was observed. Western blotting results confirmed that membrane NKCC2 had significantly higher abundance in the dDAVP-treated mouse colonic mucosa relative to that in the untreated control, which is consistent with our immunostaining data. Moreover, the short-circuit current method combined with a NKCC2 inhibitor demonstrated that NKCC2 was also activated by serosal vasopressin in isolated distal colonic mucosa.
CONCLUSION: Our results provide direct evidence that vasopressin also plays an important role in the colonic epithelia by stimulating NKCC2 trafficking to the apical membrane and inducing NKCC2-mediated ion transport.
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15
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Ding B, Frisina RD, Zhu X, Sakai Y, Sokolowski B, Walton JP. Direct control of Na(+)-K(+)-2Cl(-)-cotransport protein (NKCC1) expression with aldosterone. Am J Physiol Cell Physiol 2013; 306:C66-75. [PMID: 24173102 DOI: 10.1152/ajpcell.00096.2013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Sodium/potassium/chloride cotransporter (NKCC1) proteins play important roles in Na(+) and K(+) concentrations in key physiological systems, including cardiac, vascular, renal, nervous, and sensory systems. NKCC1 levels and functionality are altered in certain disease states, and tend to decline with age. A sensitive, effective way of regulating NKCC1 protein expression has significant biotherapeutic possibilities. The purpose of the present investigation was to determine if the naturally occurring hormone aldosterone (ALD) could regulate NKCC1 protein expression. Application of ALD to a human cell line (HT-29) revealed that ALD can regulate NKCC1 protein expression, quite sensitively and rapidly, independent of mRNA expression changes. Utilization of a specific inhibitor of mineralocorticoid receptors, eplerenone, implicated these receptors as part of the ALD mechanism of action. Further experiments with cycloheximide (protein synthesis inhibitor) and MG132 (proteasome inhibitor) revealed that ALD can upregulate NKCC1 by increasing protein stability, i.e., reducing ubiquitination of NKCC1. Having a procedure for controlling NKCC1 protein expression opens the doors for therapeutic interventions for diseases involving the mis-regulation or depletion of NKCC1 proteins, for example during aging.
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Affiliation(s)
- Bo Ding
- Department of Communication Sciences and Disorders, Global Center for Hearing and Speech Research, University of South Florida, Tampa, Florida
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16
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Melo Z, de los Heros P, Cruz-Rangel S, Vázquez N, Bobadilla NA, Pasantes-Morales H, Alessi DR, Mercado A, Gamba G. N-terminal serine dephosphorylation is required for KCC3 cotransporter full activation by cell swelling. J Biol Chem 2013; 288:31468-76. [PMID: 24043619 PMCID: PMC3814743 DOI: 10.1074/jbc.m113.475574] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The K+:Cl− cotransporter (KCC) activity is modulated by phosphorylation/dephosphorylation processes. In isotonic conditions, KCCs are inactive and phosphorylated, whereas hypotonicity promotes their dephosphorylation and activation. Two phosphorylation sites (Thr-991 and Thr-1048) in KCC3 have been found to be critical for its regulation. However, here we show that the double mutant KCC3-T991A/T1048A could be further activated by hypotonicity, suggesting that additional phosphorylation site(s) are involved. We observed that in vitro activated STE20/SPS1-related proline/alanine-rich kinase (SPAK) complexed to its regulatory MO25 subunit phosphorylated KCC3 at Ser-96 and that in Xenopus laevis oocytes Ser-96 of human KCC3 is phosphorylated in isotonic conditions and becomes dephosphorylated during incubation in hypotonicity, leading to a dramatic increase in KCC3 function. Additionally, WNK3, which inhibits the activity of KCC3, promoted phosphorylation of Ser-96 as well as Thr-991 and Thr-1048. These observations were corroborated in HEK293 cells stably transfected with WNK3. Mutation of Ser-96 alone (KCC3-S96A) had no effect on the activity of the cotransporter when compared with wild type KCC3. However, when compared with the double mutant KCC3-T991A/T1048A, the triple mutant KCC3-S96A/T991A/T1048A activity in isotonic conditions was significantly higher, and it was not further increased by hypotonicity or inhibited by WNK3. We conclude that serine residue 96 of human KCC3 is a third site that has to be dephosphorylated for full activation of the cotransporter during hypotonicity.
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Affiliation(s)
- Zesergio Melo
- From the Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, 14000 Mexico City, Mexico
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17
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Ryu JH, Walcott BP, Kahle KT, Sheth SA, Peterson RT, Nahed BV, Coumans JVCE, Simard JM. Induced and Sustained Hypernatremia for the Prevention and Treatment of Cerebral Edema Following Brain Injury. Neurocrit Care 2013; 19:222-31. [DOI: 10.1007/s12028-013-9824-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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18
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Zhou B, Wang D, Feng X, Zhang Y, Wang Y, Zhuang J, Zhang X, Chen G, Delpire E, Gu D, Cai H. WNK4 inhibits NCC protein expression through MAPK ERK1/2 signaling pathway. Am J Physiol Renal Physiol 2012; 302:F533-9. [PMID: 22114204 PMCID: PMC3353643 DOI: 10.1152/ajprenal.00032.2011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 11/18/2011] [Indexed: 11/22/2022] Open
Abstract
WNK [with no lysine (K)] kinase is a subfamily of serine/threonine kinases. Mutations in two members of this family (WNK1 and WNK4) cause pseudohypoaldosteronism type II featuring hypertension, hyperkalemia, and metabolic acidosis. WNK1 and WNK4 were shown to regulate sodium chloride cotransporter (NCC) activity through phosphorylating SPAK and OSR1. Previous studies including ours have also shown that WNK4 inhibits NCC function and its protein expression. A recent study reported that a phorbol ester inhibits NCC function via activation of extracellular signal-regulated kinase (ERK) 1/2 kinase. In the current study, we investigated whether WNK4 affects NCC via the MAPK ERK1/2 signaling pathway. We found that WNK4 increased ERK1/2 phosphorylation in a dose-dependent manner in mouse distal convoluted tubule (mDCT) cells, whereas WNK4 mutants with the PHA II mutations (E562K and R1185C) lost the ability to increase the ERK1/2 phosphorylation. Hypertonicity significantly increased ERK1/2 phosphorylation in mDCT cells. Knock-down of WNK4 expression by siRNA resulted in a decrease of ERK1/2 phosphorylation. We further showed that WNK4 knock-down significantly increases the cell surface and total NCC protein expressions and ERK1/2 knock-down also significantly increases cell surface and total NCC expression. These data suggest that WNK4 inhibits NCC through activating the MAPK ERK1/2 signaling pathway.
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Affiliation(s)
- Bo Zhou
- Renal Div., Emory Univ. School of Medicine, Atlanta, GA 30322, USA.
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19
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An autocrine neuronal interleukin-6 loop mediates chloride accumulation and NKCC1 phosphorylation in axotomized sensory neurons. J Neurosci 2011; 31:13516-26. [PMID: 21940443 DOI: 10.1523/jneurosci.3382-11.2011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The cation-chloride cotransporter NKCC1 plays a fundamental role in the central and peripheral nervous systems by setting the value of intracellular chloride concentration. Following peripheral nerve injury, NKCC1 phosphorylation-induced chloride accumulation contributes to neurite regrowth of sensory neurons. However, the molecules and signaling pathways that regulate NKCC1 activity remain to be identified. Functional analysis of cotransporter activity revealed that inhibition of endogenously produced cytokine interleukin-6 (IL-6), with anti-mouse IL-6 antibody or in IL-6⁻/⁻ mice, prevented chloride accumulation in a subset of axotomized neurons. Nerve injury upregulated the transcript and protein levels of IL-6 receptor in myelinated, TrkB-positive sensory neurons of murine lumbar dorsal root ganglia. Expression of phospho-NKCC1 was observed mainly in sensory neurons expressing IL-6 receptor and was absent from IL-6⁻/⁻ dorsal root ganglia. The use of IL-6 receptor blocking-function antibody or soluble IL-6 receptor, together with pharmacological inhibition of Janus kinase, confirmed the role of neuronal IL-6 signaling in chloride accumulation and neurite growth of a subset of axotomized sensory neurons. Cell-specific expression of interleukin-6 receptor under pathophysiological conditions is therefore a cellular response by which IL-6 contributes to nerve regeneration through neuronal NKCC1 phosphorylation and chloride accumulation.
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20
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Monette MY, Forbush B. Regulatory activation is accompanied by movement in the C terminus of the Na-K-Cl cotransporter (NKCC1). J Biol Chem 2011; 287:2210-20. [PMID: 22121194 DOI: 10.1074/jbc.m111.309211] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Na-K-Cl cotransporter (NKCC1) is expressed in most vertebrate cells and is crucial in the regulation of cell volume and intracellular chloride concentration. To study the structure and function of NKCC1, we tagged the transporter with cyan (CFP) and yellow (YFP) fluorescent proteins at two sites within the C terminus and measured fluorescence resonance energy transfer (FRET) in stably expressing human embryonic kidney cell lines. Both singly and doubly tagged NKCC1s were appropriately produced, trafficked to the plasma membrane, and exhibited (86)Rb transport activity. When both fluorescent probes were placed within the same C terminus of an NKCC1 transporter, we recorded an 11% FRET decrease upon activation of the transporter. This result clearly demonstrates movement of the C terminus during the regulatory response to phosphorylation of the N terminus. When we introduced CFP and YFP separately in different NKCC1 constructs and cotransfected these in HEK cells, we observed FRET between dimer pairs, and the fractional FRET decrease upon transporter activation was 46%. Quantitatively, this indicates that the largest FRET-signaled movement is between dimer pairs, an observation supported by further experiments in which the doubly tagged construct was cotransfectionally diluted with untagged NKCC1. Our results demonstrate that regulation of NKCC1 is accompanied by a large movement between two positions in the C termini of a dimeric cotransporter. We suggest that the NKCC1 C terminus is involved in transport regulation and that dimerization may play a key structural role in the regulatory process. It is anticipated that when combined with structural information, our findings will provide a model for understanding the conformational changes that bring about NKCC1 regulation.
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Affiliation(s)
- Michelle Y Monette
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut 06520, USA.
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21
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Zhu JX, Xue H, Ji T, Xing Y. Cellular localization of NKCC2 and its possible role in the Cl- absorption in the rat and human distal colonic epithelia. Transl Res 2011; 158:146-54. [PMID: 21867980 DOI: 10.1016/j.trsl.2011.04.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 04/07/2011] [Accepted: 04/20/2011] [Indexed: 12/16/2022]
Abstract
Recently, we demonstrated the expression of NKCC2, an absorptive isoform of NKCC specifically expressed in the kidney, in the rat gastrointestinal tract including the distal colonic mucosa. This study aims to investigate its localization in colonic epithelia and possible role in the colonic ion transport. Reverse transcription polymerase chain reaction (RT-PCR), Western blotting, and immunohistochemistry were used to investigate the expression and localization of NKCC2. The role of NKCC2 on the colonic ion transport was examined by mean of short-circuit current (I(SC)) monitoring. The results indicated that NKCC2 was expressed in the apical region of the epithelia in rat distal colon and human sigmoid colon. NKCC1, which is a secretive NKCC isoform, was localized predominantly in the basolateral membrane, which has been well documented. Serosal (basolateral) administration of bumetanide, an inhibitor of both NKCC1 and NKCC2, inhibited serosal forskolin-induced I(SC) increase by 66% but enhanced the luminal (apical) forskolin-induced I(SC) response by 63%. Furthermore, the blocking of epithelial Na(+) channels by apical addition of amiloride (10 μmol/L), K(+) channels by tetraethylammoniumion (TEA) (5 mmol/L), or glibenclimide (0.1 mmol/L) did not affect apical forskolin-induced I(SC) increase, excluding the involvement of cations, Na(+) and K(+), in the I(SC) response. The luminal forskolin-induced I(SC) increase was enhanced markedly by the apical pretreatment with bumetanide or the reduction of apical Cl(-) concentration by 114% and 198%, respectively, which were inhibited by apical addition of glibenclimide (1 mmol/L) by more than 60%. This finding suggests the involvement of an anion. Furthermore, the removal of basolateral HCO(3)(-) reduced apical forskolin-induced I(SC) by more than 75% indicated that the apical forskolin-induced I(SC) increase in rat distal colon was mediated by Cl(-) absorption and HCO(3)(-) secretion. In conclusion, NKCC2 is expressed widely in the colonic epithelium in rat distal colon and human sigmoid colon, especially in the apical membrane. It involves the process of colonic Cl(-) absorption coupled with HCO(3)(-) secretion.
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Affiliation(s)
- Jin-Xia Zhu
- Department of Anatomy and Physiology, Basic Medical College, Xinxiang Medical University, Xinxiang, Henan, China.
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22
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siRNA-Mediated Inhibition of Na+ –K+–2Cl− Cotransporter (NKCC1) and Regulatory Volume Increase in the Chondrocyte Cell Line C-20/A4. J Membr Biol 2011; 243:25-34. [DOI: 10.1007/s00232-011-9389-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 07/17/2011] [Indexed: 10/17/2022]
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23
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Hannemann A, Flatman PW. Phosphorylation and transport in the Na-K-2Cl cotransporters, NKCC1 and NKCC2A, compared in HEK-293 cells. PLoS One 2011; 6:e17992. [PMID: 21464992 PMCID: PMC3064583 DOI: 10.1371/journal.pone.0017992] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 02/17/2011] [Indexed: 11/25/2022] Open
Abstract
Na-K-2Cl cotransporters help determine cell composition and volume. NKCC1 is widely distributed whilst NKCC2 is only found in the kidney where it plays a vital role reabsorbing 20% of filtered NaCl. NKCC2 regulation is poorly understood because of its restricted distribution and difficulties with its expression in mammalian cell cultures. Here we compare phosphorylation of the N-termini of the cotransporters, measured with phospho-specific antibodies, with bumetanide-sensitive transport of K+ (86Rb+) (activity) in HEK-293 cells stably expressing fNKCC1 or fNKCC2A which were cloned from ferret kidney. Activities of transfected transporters were distinguished from those of endogenous ones by working at 37°C. fNKCC1 and fNKCC2A activities were highest after pre-incubation of cells in hypotonic low-[Cl−] media to reduce cell [Cl−] and volume during flux measurement. Phosphorylation of both transporters more than doubled. Pre-incubation with ouabain also strongly stimulated fNKCC1 and fNKCC2A and substantially increased phosphorylation, whereas pre-incubation in Na+-free media maximally stimulated fNKCC1 and doubled its phosphorylation, but inhibited fNKCC2A, with a small increase in its phosphorylation. Kinase inhibitors halved phosphorylation and activity of both transporters whereas inhibition of phosphatases with calyculin A strongly increased phosphorylation of both transporters but only slightly stimulated fNKCC1 and inhibited fNCCC2A. Thus kinase inhibition reduced phosphorylation and transport, and transport stimulation was only seen when phosphorylation increased, but transport did not always increase with phosphorylation. This suggests phosphorylation of the N-termini determines the transporters' potential capacity to move ions, but final activity also depends on other factors. Transport cannot be reliably inferred solely using phospho-specific antibodies on whole-cell lysates.
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Affiliation(s)
- Anke Hannemann
- Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, United Kingdom
| | - Peter W. Flatman
- Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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24
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Axonal GABAA receptors increase cerebellar granule cell excitability and synaptic activity. J Neurosci 2011; 31:565-74. [PMID: 21228165 DOI: 10.1523/jneurosci.4506-10.2011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report that activation of GABA(A) receptors on cerebellar granule cell axons modulates both transmitter release and the excitability of the axon and soma. Axonal GABA(A) receptors depolarize the axon, increasing its excitability and causing calcium influx at axonal varicosities. GABA-mediated subthreshold depolarizations in the axon spread electrotonically to the soma, promoting orthodromic action potential initiation. When chloride concentrations are unperturbed, GABA iontophoresis elicits spikes and increases excitability of parallel fibers, indicating that GABA(A) receptor-mediated responses are normally depolarizing. GABA release from molecular layer interneurons activates parallel fiber GABA(A) receptors, and this, in turn, increases release probability at synapses between parallel fibers and molecular layer interneurons. These results describe a positive feedback mechanism whereby transmission from granule cells to Purkinje cells and molecular layer interneurons will be strengthened during granule cell spike bursts evoked by sensory stimulation.
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25
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Pacheco-Alvarez D, Gamba G. WNK3 is a Putative Chloride-sensing Kinase. Cell Physiol Biochem 2011; 28:1123-34. [DOI: 10.1159/000335848] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2011] [Indexed: 11/19/2022] Open
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26
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Adermark L, Clarke RBC, Olsson T, Hansson E, Söderpalm B, Ericson M. Implications for glycine receptors and astrocytes in ethanol-induced elevation of dopamine levels in the nucleus accumbens. Addict Biol 2011; 16:43-54. [PMID: 20331561 DOI: 10.1111/j.1369-1600.2010.00206.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Elevated dopamine levels are believed to contribute to the rewarding sensation of ethanol (EtOH), and previous research has shown that strychnine-sensitive glycine receptors in the nucleus accumbens (nAc) are involved in regulating dopamine release and in mediating the reinforcing effects of EtOH. Furthermore, the osmoregulator taurine, which is released from astrocytes treated with EtOH, can act as an endogenous ligand for the glycine receptor, and increase extracellular dopamine levels. The aim of this study was to address if EtOH-induced swelling of astrocytes could contribute to elevated dopamine levels by increasing the extracellular concentration of taurine. Cell swelling was estimated by optical sectioning of fluorescently labeled astrocytes in primary cultures from rat, and showed that EtOH (25-150 mM) increased astrocyte cell volumes in a concentration- and ion-dependent manner. The EtOH-induced cell swelling was inhibited in cultures treated with the Na(+) /K(+) /2Cl⁻ cotransporter blocker furosemide (1 mM), Na(+) /K(+) -ATPase inhibitor ouabain (0.1 mM), potassium channel inhibitor BaCl₂ (50 µM) and in cultures containing low extracellular sodium concentration (3 mM). In vivo microdialysis performed in the nAc of awake and freely moving rats showed that local treatment with EtOH enhanced the concentrations of dopamine and taurine in the microdialysate, while glycine and β-alanine levels were not significantly modulated. EtOH-induced dopamine release was antagonized by local treatment with the glycine receptor antagonist strychnine (20 µM) or furosemide (100 µM or 1 mM). Furosemide also prevented EtOH-induced taurine release in the nAc. In conclusion, our data suggest that extracellular concentrations of dopamine and taurine are interconnected and that swelling of astrocytes contributes to the acute rewarding sensation of EtOH.
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Affiliation(s)
- Louise Adermark
- Department of Psychiatry and Neurochemistry, Institute for Neuroscience and Physiology, University of Gothenburg, Sweden.
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27
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Arion D, Lewis DA. Altered expression of regulators of the cortical chloride transporters NKCC1 and KCC2 in schizophrenia. ARCHIVES OF GENERAL PSYCHIATRY 2011; 68:21-31. [PMID: 20819979 PMCID: PMC3015012 DOI: 10.1001/archgenpsychiatry.2010.114] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
CONTEXT Disturbances in markers of cortical γ-aminobutyric acid neurotransmission are a common finding in schizophrenia. The nature of γ-aminobutyric acid neurotransmission (hyperpolarizing or depolarizing) depends on the local intracellular chloride concentration. In the central nervous system, the intracellular chloride level is determined by the activity of 2 cation-chloride transporters, NKCC1 and KCC2. The activities of these transporters are in turn regulated by a network of serine-threonine kinases that includes OXSR1, STK39, and the WNK kinases WNK1, WNK3, and WNK4. OBJECTIVE To compare the levels of NKCC1, KCC2, OXSR1, STK39, WNK1, WNK3, and WNK4 transcripts in prefrontal cortex area 9 between subjects with schizophrenia and healthy comparison subjects. DESIGN Real-time quantitative polymerase chain reaction technique was used to measure transcript levels in the prefrontal cortex. SETTING Human brain specimens were obtained from autopsies conducted at the Allegheny County Medical Examiner's Office, Pittsburgh, Pennsylvania. PARTICIPANTS Postmortem brain specimens from 42 subjects with schizophrenia and 42 matched healthy comparison subjects. Brain specimens from 18 macaque monkeys exposed to haloperidol, olanzapine, or sham long-term. MAIN OUTCOME MEASURES Relative expression levels for NKCC1, KCC2, OXSR1, STK39, WNK1, WNK3, and WNK4 transcripts compared with the mean expression level of 3 housekeeping transcripts. RESULTS OXSR1 and WNK3 transcripts were substantially overexpressed in subjects with schizophrenia relative to comparison subjects. In contrast, NKCC1, KCC2, STK39, WNK1, and WNK4 transcript levels did not differ between subject groups. OXSR1 and WNK3 transcript expression levels were not changed in antipsychotic-exposed monkeys and were not affected by potential confounding factors in the subjects with schizophrenia. CONCLUSION In schizophrenia, increased expression levels, and possibly increased kinase activities, of OXSR1 and WNK3 may shift the balance of chloride transport by NKCC1 and KCC2 and alter the nature of γ-aminobutyric acid neurotransmission in the prefrontal cortex.
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Affiliation(s)
- Dominique Arion
- Department of Psychiatry, University of Pittsburgh, PA 15213, USA
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28
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Phosphoregulation of the Na-K-2Cl and K-Cl cotransporters by the WNK kinases. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1150-8. [PMID: 20637866 PMCID: PMC3529164 DOI: 10.1016/j.bbadis.2010.07.009] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Revised: 07/07/2010] [Accepted: 07/08/2010] [Indexed: 11/23/2022]
Abstract
Precise regulation of the intracellular concentration of chloride [Cl-]i is necessary for proper cell volume regulation, transepithelial transport, and GABA neurotransmission. The Na-K-2Cl (NKCCs) and K-Cl (KCCs) cotransporters, related SLC12A transporters mediating cellular chloride influx and efflux, respectively, are key determinants of [Cl-]i in numerous cell types, including red blood cells, epithelial cells, and neurons. A common "chloride/volume-sensitive kinase", or related system of kinases, has long been hypothesized to mediate the reciprocal but coordinated phosphoregulation of the NKCCs and the KCCs, but the identity of these kinase(s) has remained unknown. Recent evidence suggests that the WNK (with no lysine = K) serine-threonine kinases directly or indirectly via the downstream Ste20-type kinases SPAK/OSR1, are critical components of this signaling pathway. Hypertonic stress (cell shrinkage), and possibly decreased [Cl-]i, triggers the phosphorylation and activation of specific WNKs, promoting NKCC activation and KCC inhibition via net transporter phosphorylation. Silencing WNK kinase activity can promote NKCC inhibition and KCC activation via net transporter dephosphorylation, revealing a dynamic ability of the WNKs to modulate [Cl-]. This pathway is essential for the defense of cell volume during osmotic perturbation, coordination of epithelial transport, and gating of sensory information in the peripheral system. Commiserate with their importance in serving these critical roles in humans, mutations in WNKs underlie two different Mendelian diseases, pseudohypoaldosteronism type II (an inherited form of salt-sensitive hypertension), and hereditary sensory and autonomic neuropathy type 2. WNKs also regulate ion transport in lower multicellular organisms, including Caenorhabditis elegans, suggesting that their functions are evolutionarily-conserved. An increased understanding of how the WNKs regulate the Na-K-2Cl and K-Cl cotransporters may provide novel opportunities for the selective modulation of these transporters, with ramifications for common human diseases like hypertension, sickle cell disease, neuropathic pain, and epilepsy.
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29
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Bush PG, Pritchard M, Loqman MY, Damron TA, Hall AC. A key role for membrane transporter NKCC1 in mediating chondrocyte volume increase in the mammalian growth plate. J Bone Miner Res 2010; 25:1594-603. [PMID: 20200963 PMCID: PMC3154001 DOI: 10.1002/jbmr.47] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The mechanisms that underlie growth plate chondrocyte volume increase and hence bone lengthening are poorly understood. Many cell types activate the Na-K-Cl cotransporter (NKCC) to bring about volume increase. We hypothesised that NKCC may be responsible for the volume expansion of hypertrophic chondrocytes. Metatarsals/metacarpals from 16 rat pups (P(7)) were incubated in the presence/absence of the specific NKCC inhibitor bumetanide and measurement of whole-bone lengths and histologic analysis of the growth plate were done after 24 hours. Fluorescent NKCC immunohistochemistry was visualised using a confocal laser scanning microscopy on seven rat tibial growth plates (P(7)). Microarray analysis was performed on mRNA isolated from proliferative and hypertrophic zone cells of tibial growth plates from five rats of each of three ages (P(49/53/58)). Exposure to bumetanide resulted in approximately 35% reduction (paired Student's t test, p < .05) of bone growth in a dose-dependent manner; histologic analysis showed that a reduction in hypertrophic zone height was responsible. Quantification of fluorescence immunohistochemistry revealed a significant (paired Student's t test, p < .05) change in NKCC from the intracellular space of proliferative cells to the cytosolic membrane of hypertrophic zone cells. Further, microarray analysis illustrated an increase in NKCC1 mRNA between proliferative and hypertrophic cells. The increase in NKCC1 mRNA in hypertrophic zone cells, its cellular localization, and reduced bone growth in the presence of the NKCC inhibitor bumetanide implicate NKCC in growth plate hypertrophic chondrocyte volume increase. Further investigation is warranted to determine the regulatory control of NKCC in the mammalian growth plate and the possible detrimental effect on bone growth with chronic exposure to loop diuretics.
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Affiliation(s)
- Peter G Bush
- Centre for Biomedical and Health Science Research, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK.
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30
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Ong SB, Shah D, Qusous A, Jarvis SM, Kerrigan MJ. Stimulation of regulatory volume increase (RVI) in avian articular chondrocytes by gadolinium chloride. Biochem Cell Biol 2010; 88:505-12. [DOI: 10.1139/o09-179] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chondrocytes, the resident cell-type of articular cartilage, are responsible for the regulation of the extracellular matrix (ECM) in response to their physico-chemical environment. Due to the nature of cartilage loading, chondrocytes are exposed to constant changes in extracellular osmolality with a gradual increase throughout the day. As an increase in osmolality attenuates matrix synthesis, we have studied cell volume regulation (regulatory volume increase (RVI)) after hypertonic challenge and the regulation of RVI by the actin cytoskeleton. Using freshly isolated avian articular chondrocytes, changes in actin organisation were studied by confocal laser scanning microscopy following a 43% increase in extracellular osmolality. Using calcein-loading chondrocytes, the capacity for RVI was determined and the rate of volume recovery (t1/2) mathematically extrapolated. Following an increase in extracellular osmolality there was a significant increase (p < 0.05) in cortical actin, inhibited by the removal of extracellular calcium EGTA or by the addition of 100 µmol·L–1 gadolinium chloride. Most cells exhibited slow RVI (t1/2 = 55.5 ± 5.5 min), whereby inhibition of actin polymerisation by gadolinium chloride or the removal of extracellular calcium significantly increased the rate of volume recovery via a bumetanide-sensitive pathway (t1/2 of 29.6 ± 6.5 min and 13.8 ± 3.1 min, respectively). These data suggest the Na+–K+–2Cl– (NKCC) co-transporter regulated by the actin cytoskeleton is involved in avian chondrocyte RVI.
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Affiliation(s)
- Sang-Bing Ong
- Department of Human & Health Sciences, School of Life Sciences, University of Westminster, 115 New Cavendish St., London W1W 6UW, UK
- The Hatter Cardiovascular Institute, University College London Hospital & Medical School, 67 Chenies Mews, London WC1E 6HX, UK
- University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK
| | - Dinesh Shah
- Department of Human & Health Sciences, School of Life Sciences, University of Westminster, 115 New Cavendish St., London W1W 6UW, UK
- The Hatter Cardiovascular Institute, University College London Hospital & Medical School, 67 Chenies Mews, London WC1E 6HX, UK
- University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK
| | - Ala Qusous
- Department of Human & Health Sciences, School of Life Sciences, University of Westminster, 115 New Cavendish St., London W1W 6UW, UK
- The Hatter Cardiovascular Institute, University College London Hospital & Medical School, 67 Chenies Mews, London WC1E 6HX, UK
- University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK
| | - Simon M. Jarvis
- Department of Human & Health Sciences, School of Life Sciences, University of Westminster, 115 New Cavendish St., London W1W 6UW, UK
- The Hatter Cardiovascular Institute, University College London Hospital & Medical School, 67 Chenies Mews, London WC1E 6HX, UK
- University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK
| | - Mark J.P. Kerrigan
- Department of Human & Health Sciences, School of Life Sciences, University of Westminster, 115 New Cavendish St., London W1W 6UW, UK
- The Hatter Cardiovascular Institute, University College London Hospital & Medical School, 67 Chenies Mews, London WC1E 6HX, UK
- University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK
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31
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Evans TG. Co-ordination of osmotic stress responses through osmosensing and signal transduction events in fishes. JOURNAL OF FISH BIOLOGY 2010; 76:1903-1925. [PMID: 20557646 DOI: 10.1111/j.1095-8649.2010.02590.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
This review centres upon the molecular regulation of osmotic stress responses in fishes, focusing on how osmosensing and signal transduction events co-ordinate changes in the activity and abundance of effector proteins during osmotic stress and how these events integrate into osmotic stress responses of varying magnitude. The concluding sections discuss the relevance of osmosensory signal transduction to the evolution of euryhalinity and present experimental approaches that may best stimulate future research. Iterating the importance of osmosensing and signal transduction during fish osmoregulation may be pertinent amidst the increased use of genomic technologies that typically focus solely on changes in the abundances of gene products, and may limit insight into critical upstream events that occur mainly through post-translational mechanisms.
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Affiliation(s)
- T G Evans
- Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA.
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32
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Hannemann A, Christie JK, Flatman PW. Functional expression of the Na-K-2Cl cotransporter NKCC2 in mammalian cells fails to confirm the dominant-negative effect of the AF splice variant. J Biol Chem 2009; 284:35348-58. [PMID: 19854835 PMCID: PMC2790964 DOI: 10.1074/jbc.m109.060004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 10/06/2009] [Indexed: 11/25/2022] Open
Abstract
The renal bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2) is the major salt transport pathway in the apical membrane of the mammalian thick ascending limb. It is differentially spliced and the three major variants (A, B, and F) differ in their localization and transport characteristics. Most knowledge about its regulation comes from experiments in Xenopus oocytes as NKCC2 proved difficult to functionally express in a mammalian system. Here we report the cloning and functional expression of untagged and unmodified versions of the major splice variants from ferret kidney (fNKCC2A, -B, and -F) in human embryonic kidney (HEK) 293 cells. Many NKCC2 antibodies used in this study detected high molecular weight forms of the transfected proteins, probably NKCC2 dimers, but not the monomers. Interestingly, monomers were strongly detected by phosphospecific antibodies directed against phosphopeptides in the regulatory N terminus. Bumetanide-sensitive (86)Rb uptake was significantly higher in transfected HEK-293 cells and could be stimulated by incubating cells in a medium containing a low chloride concentration prior the uptake measurements. fNKCC2 was less sensitive to the reduction in chloride concentration than NKCC1. Using HEK-293 cells stably expressing fNKCC2A we also show that co-expression of variant NKCC2AF does not have the dominant-negative effect on NKCC2A activity that was seen in Xenopus oocytes, nor is it trafficked to the cell surface. In addition, fNKCC2AF is neither complex glycosylated nor phosphorylated in its N terminus regulatory region like other variants.
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Affiliation(s)
- Anke Hannemann
- From the Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, The University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, Scotland, United Kingdom
| | - Jenny K. Christie
- From the Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, The University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, Scotland, United Kingdom
| | - Peter W. Flatman
- From the Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, The University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, Scotland, United Kingdom
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33
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Xue H, Liu S, Ji T, Ren W, Zhang XH, Zheng LF, Wood JD, Zhu JX. Expression of NKCC2 in the rat gastrointestinal tract. Neurogastroenterol Motil 2009; 21:1068-e89. [PMID: 19460103 DOI: 10.1111/j.1365-2982.2009.01334.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
NKCC2, an isoform of Na+-K+-2Cl(-) cotransporter, is principally present in the kidney and plays a critical role in salt reabsorption. Expression of NKCC2 has been found in the apical membrane of intestinal epithelial cells in a number of marine fish, however, details for expression in the mammalian gastrointestinal tract are lacking. RT-PCR, Western blotting and immunohistochemistry were used to study the expression and localization of NKCC2 in the rat gastrointestinal tract. We found that mRNA transcripts, protein and immunoreactivity (IR) for NKCC2 were expressed in the stomach, small and large intestine of adult rats. NKCC2 IR was localized to the base of the gastric glands, intestinal epithelia, myenteric and submucosal plexuses. NKCC2 IR was expressed strongly in the apical membranes and weakly in the basolateral membranes of intestinal epithelial cells. In the enteric nervous system, NKCC2 IR was widely distributed and localized to enteric neurons with cholinergic, calretinin and nitrergic neuronal immunochemical codes in the myenteric plexus. It was localized to non-cholinergic secretomotor neurons in the submucosal plexus. In conclusion, this study for the first time clearly detected the expression of NKCC2 in the gastrointestinal tract of a mammalian species. Expression of NKCC2 in gastrointestinal epithelial cells suggested that this cation chloride cotransporter might be involved in gastrointestinal ion transport. Expression of NKCC2 in enteric neurons might contribute to the accumulation of Cl(-) and a more depolarized E(Cl)(-) in enteric neurons.
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Affiliation(s)
- H Xue
- Department of Physiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
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34
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Pantaleo A, De Franceschi L, Ferru E, Vono R, Turrini F. Current knowledge about the functional roles of phosphorylative changes of membrane proteins in normal and diseased red cells. J Proteomics 2009; 73:445-55. [PMID: 19758581 DOI: 10.1016/j.jprot.2009.08.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 07/17/2009] [Accepted: 08/27/2009] [Indexed: 12/20/2022]
Abstract
With the advent of proteomic techniques the number of known post-translational modifications (PTMs) affecting red cell membrane proteins is rapidly growing but the understanding of their role under physiological and pathological conditions is incompletely established. The wide range of hereditary diseases affecting different red cell membrane functions and the membrane modifications induced by malaria parasite intracellular growth represent a unique opportunity to study PTMs in response to variable cellular stresses. In the present review, some of the major areas of interest in red cell membrane research have been considered as modifications of erythrocyte deformability and maintenance of the surface area, membrane transport alterations, and removal of diseased and senescent red cells. In all mentioned research areas the functional roles of PTMs are prevalently restricted to the phosphorylative changes of the more abundant membrane proteins. The insufficient information about the PTMs occurring in a large majority of the red membrane proteins and the general lack of mass spectrometry data evidence the need of new comprehensive, proteomic approaches to improve the understanding of the red cell membrane physiology.
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Affiliation(s)
- Antonella Pantaleo
- Department of Genetics, Biology and Biochemistry, University of Turin, via Santena 5 bis, 10126 Turin, Italy.
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35
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Abstract
The present contribution reviews current knowledge of apparently oxygen-dependent ion transport in erythrocytes and presents modern hypotheses on their regulatory mechanisms and physiological roles. In addition to molecular oxygen as such, reactive oxygen species, nitric oxide, carbon monoxide, regional variations of cellular ATP and hydrogen sulphide may play a role in the regulation of transport, provided that they are affected by oxygen tension. It appears that the transporter molecules themselves do not have direct oxygen sensors. Thus, the oxygen level must be sensed elsewhere, and the effect transduced to the transporter. The possible pathways involved in the regulation of transport, including haemoglobin as a sensor, and phosphorylation/dephosphorylation reactions both in the transporter and its upstream effectors, are discussed.
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Affiliation(s)
- A Bogdanova
- Institute of Veterinary Physiology and the Zurich Center for Integrative Human Physiology, University of Zurich, Wintherturerstrasse 260, Zurich, Switzerland.
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36
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Walters ZS, Haworth KE, Latinkic BV. NKCC1 (SLC12a2) induces a secondary axis in Xenopus laevis embryos independently of its co-transporter function. J Physiol 2008; 587:521-9. [PMID: 19047208 DOI: 10.1113/jphysiol.2008.161562] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
NKCC1 is a broadly expressed Na(+)-K(+)-Cl(-) co-transporter involved in regulation of ion flux across the cell membrane and in regulating cell volume. Whilst much is known about the co-transporter activity of NKCC1 and its regulation by protein kinases and phosphatases, little is known about the activities of NKCC1 that are co-transporter independent. In this report we show that over-expression of NKCC1 in embryos of Xenopus laevis induces secondary axes, independently of its co-transporter activity. In addition, over-expression of NKCC1 results in the formation of neural tissue in ectodermal explants. We also show that NKCC1 is expressed broadly but non-uniformly in embryos of Xenopus laevis and Xenopus tropicalis, with prominent expression in the notochord, nervous system and stomach. These results provide insights into an additional, previously unreported activity of NKCCl.
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Affiliation(s)
- Zoë S Walters
- Cardiff School of Bioscience, Cardiff University, Museum Avenue, Cardiff, UK
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37
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San-Cristobal P, Ponce-Coria J, Vázquez N, Bobadilla NA, Gamba G. WNK3 and WNK4 amino-terminal domain defines their effect on the renal Na+-Cl- cotransporter. Am J Physiol Renal Physiol 2008; 295:F1199-206. [PMID: 18701621 PMCID: PMC2576145 DOI: 10.1152/ajprenal.90396.2008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Accepted: 08/12/2008] [Indexed: 11/22/2022] Open
Abstract
Loss of physiological regulation of the renal thiazide-sensitive Na+-Cl- cotransporter (NCC) by mutant WNK1 or WNK4 results in pseudohypoaldosteronism type II (PHAII) characterized by arterial hypertension and hyperkalemia. WNK4 normally inhibits NCC, but this effect is lost by eliminating WNK4 catalytic activity or through PHAII-type mutations. In contrast, another member of the WNK family, WNK3, activates NCC. The positive effect of WNK3 on NCC also requires its catalytic activity. Because the opposite effects of WNK3 and WNK4 on NCC were observed in the same expression system, sequences within the WNKs should endow these kinases with their activating or inhibiting properties. To gain insight into the structure-function relationships between the WNKs and NCC, we used a chimera approach between WNK3 and WNK4 to elucidate the domain of the WNKs responsible for the effects on NCC. Chimeras were constructed by swapping the amino or carboxyl terminus domains, which flank the central kinase domain, between WNK3 and WNK4. Our results show that the effect of chimeras toward NCC follows the amino-terminal domain. Thus the amino terminus of the WNKs contains the sequences that are required for their activating or inhibiting properties on NCC.
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Affiliation(s)
- Pedro San-Cristobal
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Vasco de Quiroga no. 15, Tlalpan 14000, Mexico City, Mexico
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38
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Kahle KT, Staley KJ, Nahed BV, Gamba G, Hebert SC, Lifton RP, Mount DB. Roles of the cation-chloride cotransporters in neurological disease. NATURE CLINICAL PRACTICE. NEUROLOGY 2008; 4:490-503. [PMID: 18769373 DOI: 10.1038/ncpneuro0883] [Citation(s) in RCA: 289] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Accepted: 07/08/2008] [Indexed: 02/02/2023]
Abstract
In the nervous system, the intracellular chloride concentration ([Cl(-)](i)) determines the strength and polarity of gamma-aminobutyric acid (GABA)-mediated neurotransmission. [Cl(-)](i) is determined, in part, by the activities of the SLC12 cation-chloride cotransporters (CCCs). These transporters include the Na-K-2Cl cotransporter NKCC1, which mediates chloride influx, and various K-Cl cotransporters--such as KCC2 and KCC3-that extrude chloride. A precise balance between NKCC1 and KCC2 activity is necessary for inhibitory GABAergic signaling in the adult CNS, and for excitatory GABAergic signaling in the developing CNS and the adult PNS. Altered chloride homeostasis, resulting from mutation or dysfunction of NKCC1 and/or KCC2, causes neuronal hypoexcitability or hyperexcitability; such derangements have been implicated in the pathogenesis of seizures and neuropathic pain. [Cl(-)](i) is also regulated to maintain normal cell volume. Dysfunction of NKCC1 or of swelling-activated K-Cl cotransporters has been implicated in the damaging secondary effects of cerebral edema after ischemic and traumatic brain injury, as well as in swelling-related neurodegeneration. CCCs represent attractive therapeutic targets in neurological disorders the pathogenesis of which involves deranged cellular chloride homoestasis.
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Affiliation(s)
- Kristopher T Kahle
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
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39
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Tsutsumi T, Kosaka T, Ushiro H, Kimura K, Honda T, Kayahara T, Mizoguchi A. PASK (proline-alanine-rich Ste20-related kinase) binds to tubulin and microtubules and is involved in microtubule stabilization. Arch Biochem Biophys 2008; 477:267-78. [PMID: 18675246 DOI: 10.1016/j.abb.2008.07.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 07/01/2008] [Accepted: 07/13/2008] [Indexed: 11/17/2022]
Abstract
Proline-alanine-rich Ste20-related kinase (PASK, also referred to as SPAK) has been linked to ion transport regulation. Here, we report two novel activities of PASK: binding to tubulin and microtubules and the promotion of microtubule assembly. Tubulin binding assay showed that full-length PASK and its kinase domain bound to purified tubulin whereas the N-terminal or C-terminal non-catalytic domains of PASK did not. The full-length PASK and its kinase domain were sedimented with paclitaxel-stabilized microtubules by ultracentrifugation. These results indicate that the kinase domain of PASK can interact directly with both microtubules and soluble tubulin in vitro. Truncated PASK lacking the N-terminal non-catalytic domain promoted microtubule assembly at a subcritical concentration of purified tubulin. FLAG-PASK expressed in COS-7 cells translocated to the cytoskeleton when the cells were stimulated with hypertonic sodium chloride, and stabilized microtubules against depolymerization by nocodazole. Our findings suggest that PASK may regulate the cytoskeleton by modulating microtubule stability.
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Affiliation(s)
- Tomonari Tsutsumi
- Department of Neural Regeneration and Cell Communication, Mie University Graduate School of Medicine, Tsu, Mie 514-8507, Japan
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40
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Marshall W, Katoh F, Main H, Sers N, Cozzi R. Focal adhesion kinase and β1 integrin regulation of Na+, K+, 2Cl− cotransporter in osmosensing ion transporting cells of killifish, Fundulus heteroclitus. Comp Biochem Physiol A Mol Integr Physiol 2008; 150:288-300. [DOI: 10.1016/j.cbpa.2008.03.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2007] [Revised: 03/13/2008] [Accepted: 03/17/2008] [Indexed: 12/31/2022]
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41
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Jing Y, Dowdy JA, Van Scott MR, Fedan JS. Hyperosmolarity-induced dilation and epithelial bioelectric responses of guinea pig trachea in vitro: role of kinase signaling. J Pharmacol Exp Ther 2008; 326:186-95. [PMID: 18413857 DOI: 10.1124/jpet.107.135871] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Exercise-induced airway obstruction is thought to involve evaporative water loss and hyperosmolarity of the airway surface liquid. Hyperosmolar challenge of the epithelium of isolated, perfused guinea pig trachea rapidly alters transepithelial potential difference (V(t)), and it elicits smooth muscle relaxation mediated by epithelium-derived relaxing factor (EpDRF). In many cell types, protein kinases mediate responses to hyperosmolarity and regulatory volume increase. In this study, inhibitors were used to investigate the involvement of kinases and phosphatases in bioelectric responses of epithelium to hyperosmolarity and their possible relationship to EpDRF-mediated relaxation. After contraction of the perfused trachea with extraluminal methacholine, D-mannitol applied intraluminally (< or = 80 mosM) increased V(t) and elicited dilation of the smooth muscle with a similar concentration-dependence; higher concentrations decreased V(t). In tracheas exposed to 30 mosM D-mannitol (approximately EC(50)), 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB 203580) and SKF 86002 [6-(4-fluorophenyl)-2,3-dihydro-5-(4-pyridyl)imidazo[2,1-b]thiazole] (p38 inhibitors) potentiated the dilation, whereas SP 600125 [anthra[1,9-cd]pyrazol-6(2H)-one-1,9-pyrazoloanthrone] and dicumarol [c-Jun NH(2)-terminal kinase (JNK) inhibitors], chelerythrine [nonselective protein kinase C (PKC) inhibitor], and NaAsO(2) (mitogen-activated protein kinase stress inducer) and Na(3)VO(4) (protein tyrosine phosphatase inhibitor) inhibited the hyperpolarization. Large increases in the phosphorylation of p38 and JNK occurred at concentrations higher than those needed to elicit functional responses. The phosphatidylinositol 3-kinase inhibitor 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY 294002) and Na(3)VO(4) did not affect the V(t) responses, but they inhibited methacholine-induced constriction; SP 600125 and dicumarol potentiated, and chelerythrine inhibited, methacholine-induced epithelial hyperpolarization. These results suggest that JNK, PKC, and phosphatase(s) are involved in hyperosmolarity-induced hyperpolarization of the tracheal epithelium but that p38 is involved in EpDRF-mediated relaxation.
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Affiliation(s)
- Yi Jing
- Department of Biochemistry and Molecular Pharmacology, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, USA
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42
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Gelpi E, Heinzl H, Höftberger R, Unterberger U, Ströbel T, Voigtländer T, Drobna E, Jarius C, Lang S, Waldhör T, Bernheimer H, Budka H. Creutzfeldt-Jakob Disease in Austria: An Autopsy-Controlled Study. Neuroepidemiology 2008; 30:215-21. [DOI: 10.1159/000126915] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Accepted: 01/29/2008] [Indexed: 11/19/2022] Open
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43
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Hoffmann EK, Schettino T, Marshall WS. The role of volume-sensitive ion transport systems in regulation of epithelial transport. Comp Biochem Physiol A Mol Integr Physiol 2007; 148:29-43. [PMID: 17289411 DOI: 10.1016/j.cbpa.2006.11.023] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2006] [Revised: 11/08/2006] [Accepted: 11/23/2006] [Indexed: 11/25/2022]
Abstract
This review focuses on using the knowledge on volume-sensitive transport systems in Ehrlich ascites tumour cells and NIH-3T3 cells to elucidate osmotic regulation of salt transport in epithelia. Using the intestine of the European eel (Anguilla anguilla) (an absorptive epithelium of the type described in the renal cortex thick ascending limb (cTAL)) we have focused on the role of swelling-activated K+- and anion-conductive pathways in response to hypotonicity, and on the role of the apical (luminal) Na+-K+-2Cl- cotransporter (NKCC2) in the response to hypertonicity. The shrinkage-induced activation of NKCC2 involves an interaction between the cytoskeleton and protein phosphorylation events via PKC and myosin light chain kinase (MLCK). Killifish (Fundulus heteroclitus) opercular epithelium is a Cl(-)-secreting epithelium of the type described in exocrine glands, having a CFTR channel on the apical side and the Na+/K+ ATPase, NKCC1 and a K+ channel on the basolateral side. Osmotic control of Cl- secretion across the operculum epithelium includes: (i) hyperosmotic shrinkage activation of NKCC1 via PKC, MLCK, p38, OSR1 and SPAK; (ii) deactivation of NKCC by hypotonic cell swelling and a protein phosphatase, and (iii) a protein tyrosine kinase acting on the focal adhesion kinase (FAK) to set levels of NKCC activity.
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Affiliation(s)
- E K Hoffmann
- Department of Molecular Biology, The August Krogh Building, University of Copenhagen, Denmark.
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44
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Pieraut S, Laurent-Matha V, Sar C, Hubert T, Méchaly I, Hilaire C, Mersel M, Delpire E, Valmier J, Scamps F. NKCC1 phosphorylation stimulates neurite growth of injured adult sensory neurons. J Neurosci 2007; 27:6751-9. [PMID: 17581962 PMCID: PMC6672700 DOI: 10.1523/jneurosci.1337-07.2007] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Peripheral nerve section promotes regenerative, elongated neuritic growth of adult sensory neurons. Although the role of chloride homeostasis, through the regulation of ionotropic GABA receptors, in the growth status of immature neurons in the CNS begins to emerge, nothing is known of its role in the regenerative growth of injured adult neurons. To analyze the intracellular Cl- variation after a sciatic nerve section in vivo, gramicidin perforated-patch recordings were used to study muscimol-induced currents in mice dorsal root ganglion neurons isolated from control and axotomized neurons. We show that the reversal potential of muscimol-induced current, E(GABA-A), was shifted toward depolarized potentials in axotomized neurons. This was attributable to Cl- influx because removal of extracellular Cl- prevented this shift. Application of bumetanide, an inhibitor of NKCC1 cotransporter and E(GABA-A) recordings in sensory neurons from NKCC1-/- mice, identified NKCC1 as being responsible for the increase in intracellular Cl- in axotomized neurons. In addition, we demonstrate with a phospho-NKCC1 antibody that nerve injury induces an increase in the phosphorylated form of NKCC1 in dorsal root ganglia that could account for intracellular Cl- accumulation. Time-lapse recordings of the neuritic growth of axotomized neurons show a faster growth velocity compared with control. Bumetanide, the intrathecal injection of NKCC1 small interfering RNA, and the use of NKCC1-/- mice demonstrated that NKCC1 is involved in determining the velocity of elongated growth of axotomized neurons. Our results clearly show that NKCC1-induced increase in intracellular chloride concentration is a major event accompanying peripheral nerve regeneration.
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Affiliation(s)
- Simon Pieraut
- Inserm, Unité 583, F-34000 Montpellier, France
- Université Montpellier II, F-34000 Montpellier, France
| | - Valérie Laurent-Matha
- Inserm, Unité 583, F-34000 Montpellier, France
- Université Montpellier II, F-34000 Montpellier, France
| | | | | | - Ilana Méchaly
- Inserm, Unité 583, F-34000 Montpellier, France
- Université Montpellier II, F-34000 Montpellier, France
| | | | | | - Eric Delpire
- Vanderbilt University, Nashville, Tennessee 37235
| | - Jean Valmier
- Inserm, Unité 583, F-34000 Montpellier, France
- Université Montpellier II, F-34000 Montpellier, France
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45
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Pitcher MH, Price TJ, Entrena JM, Cervero F. Spinal NKCC1 blockade inhibits TRPV1-dependent referred allodynia. Mol Pain 2007; 3:17. [PMID: 17603899 PMCID: PMC1929059 DOI: 10.1186/1744-8069-3-17] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Accepted: 06/30/2007] [Indexed: 01/21/2023] Open
Abstract
Background The Na+, K+, 2Cl- type I cotransporter (NKCC1) and TRPV1 receptors, at the level of the dorsal horn, have been implicated in mediating allodynia in response to an inflammatory insult. The NKCC1 cotransporter regulates intracellular [Cl-] and thus the magnitude and polarity of GABAA receptor responses in neurons. TRPV1 receptors transduce diverse chemical and natural stimuli in nociceptors and are critical for inflammatory hyperalgesia. Results Here we have tested the role of spinal NKCC1 cotransporters and TRPV1 receptors in referred allodynia in a model of visceral hyperalgesia in mice. Intrathecal (IT) injection of the NKCC1 inhibitor bumetanide (BUM, 1 nmol) inhibited referred, abdominal allodynia evoked by an intracolonic capsaicin injection. BUM was effective when injected IT either before or up to 4 hrs after the establishment of referred allodynia. The TRPV1 antagonist AMG 9810 (1 nmol) also inhibited referred allodynia in this model suggesting the involvement of an endogenous TRPV1 agonist in the dorsal horn in referred allodynia. In support of this suggestion, the endovanilloid TRPV1 agonist, narachidonoyl- dopamine (NADA, 1 or 10 nmol, IT) evoked stroking allodynia in the hindpaw that was blocked by co-treatment with AMG 9810 (1 nmol). The TRPV1-dependent stroking allodynia caused by NADA appeared to be functionally linked to NKCC1 because BUM (1 nmol) also inhibited NADA-evoked stroking allodynia. Conclusion Our findings indicate that spinal NKCC1 and TRPV1 are critical for referred allodynia mediated by a painful visceral stimulus. Moreover, they suggest that endogenous TRPV1 agonists, released in the CNS in painful conditions, might stimulate TRPV1 receptors on primary afferents that, in turn, play a role in increasing NKCC1 activity leading to allodynia.
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Affiliation(s)
- Mark H Pitcher
- McGill University, Anesthesia Research Unit, Faculty of Medicine, Faculty of Dentistry and McGill Centre for Research on Pain, 3655 Sir William Osler, McIntyre Medical Bldg 1207, Montreal, QC, H3G 1Y6, Canada
| | - Theodore J Price
- McGill University, Anesthesia Research Unit, Faculty of Medicine, Faculty of Dentistry and McGill Centre for Research on Pain, 3655 Sir William Osler, McIntyre Medical Bldg 1207, Montreal, QC, H3G 1Y6, Canada
| | - Jose M Entrena
- University of Granada Faculty of Medicine, Department of Pharmacology and Neurosciences Institute, Avenida de Madrid 12, E-18012, Granada, Spain
| | - Fernando Cervero
- McGill University, Anesthesia Research Unit, Faculty of Medicine, Faculty of Dentistry and McGill Centre for Research on Pain, 3655 Sir William Osler, McIntyre Medical Bldg 1207, Montreal, QC, H3G 1Y6, Canada
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46
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Flatman PW. Cotransporters, WNKs and hypertension: important leads from the study of monogenetic disorders of blood pressure regulation. Clin Sci (Lond) 2007; 112:203-16. [PMID: 17223794 DOI: 10.1042/cs20060225] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Major advances are being made in identifying the structure and behaviour of regulatory cascades that control the activity of cation-Cl(-) cotransporters and certain Na(+), K(+) and Cl(-) channels. These transporters play key roles in regulating arterial blood pressure as they are not only responsible for NaCl reabsorption in the thick ascending limb and distal tubule of the kidney, but are also involved in regulating smooth muscle Ca(2+) levels. It is now apparent that defects in these transporters, and particularly in the regulatory cascades, cause some monogenetic forms of hypertension and may contribute to essential hypertension and problems with K(+) homoeostasis. Two families of kinases are prominent in these processes: the Ste-20-related kinases [OSR1 (oxidative stress-responsive kinase 1) and SPAK (Ste20/SPS1-related proline/alanine-rich kinase)] and the WNKs [with no lysine kinases]. These kinases affect the behaviour of their targets through both phosphorylation and by acting as scaffolding proteins, bringing together regulatory complexes. This review analyses how these kinases affect transport by activating or inhibiting individual transporters at the cell surface, or by changing the surface density of transporters by altering the rate of insertion or removal of transporters from the cell surface, and perhaps through controlling the rate of transporter degradation. This new knowledge should not only help us target antihypertensive therapy more appropriately, but could also provide the basis for developing new therapeutic approaches to essential hypertension.
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Affiliation(s)
- Peter W Flatman
- Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh EH8 9XD, Scotland, U.K.
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Hoffmann EK, Pedersen SF. Shrinkage insensitivity of NKCC1 in myosin II-depleted cytoplasts from Ehrlich ascites tumor cells. Am J Physiol Cell Physiol 2007; 292:C1854-66. [PMID: 17229812 DOI: 10.1152/ajpcell.00474.2006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Protein phosphorylation/dephosphorylation and cytoskeletal reorganization regulate the Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) during osmotic shrinkage; however, the mechanisms involved are unclear. We show that in cytoplasts, plasma membrane vesicles detached from Ehrlich ascites tumor cells (EATC) by cytochalasin treatment, NKCC1 activity evaluated as bumetanide-sensitive (86)Rb influx was increased compared with the basal level in intact cells yet could not be further increased by osmotic shrinkage. Accordingly, cytoplasts exhibited no regulatory volume increase after shrinkage. In cytoplasts, cortical F-actin organization was disrupted, and myosin II, which in shrunken EATC translocates to the cortical region, was absent. Moreover, NKCC1 activity was essentially insensitive to the myosin light chain kinase (MLCK) inhibitor ML-7, a potent blocker of shrinkage-induced NKCC1 activity in intact EATC. Cytoplast NKCC1 activity was potentiated by the Ser/Thr protein phosphatase inhibitor calyculin A, partially inhibited by the protein kinase A inhibitor H89, and blocked by the broad protein kinase inhibitor staurosporine. Cytoplasts exhibited increased protein levels of NKCC1, Ste20-related proline- and alanine-rich kinase (SPAK), and oxidative stress response kinase 1, yet they lacked the shrinkage-induced plasma membrane translocation of SPAK observed in intact cells. The basal phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) was increased in cytoplasts compared with intact cells, yet in contrast to the substantial activation in shrunken intact cells, p38 MAPK could not be further activated by shrinkage of the cytoplasts. Together these findings indicate that shrinkage activation of NKCC1 in EATC is dependent on the cortical F-actin network, myosin II, and MLCK.
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Affiliation(s)
- Else K Hoffmann
- Department of Molecular Biology, University of Copenhagen, 13 Universitetsparken, Dk-2100 Copenhagen, Denmark.
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48
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O'Donnell ME, Lam TI, Tran L, Anderson SE. The role of the blood-brain barrier Na-K-2Cl cotransporter in stroke. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 559:67-75. [PMID: 18727228 DOI: 10.1007/0-387-23752-6_6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Studies from this and other laboratories have shown that the Na-K-2Cl cotransporter is present in BBB endothelial cells is stimulated by factors present during cerebral ischemia. Further, our in situ studies have shown that the cotransporter resides predominantly in the luminal BBB membrane. This is consistent with the hypothesis that a luminal cotransporter works with abluminal Na/K ATPase to secrete NaCl into the brain, and during stroke, BBB cotransporter activity is increased such that the barrier hypersecretes NaCl and water into the brain, facilitating cytotoxic edema formation. Our in vivo MCAO stroke studies provide further support for a role of the BBB cotransporter in cerebral ede-ma formation. Collectively, these findings suggest that the BBB Na-K-2Cl cotransporter does indeed substantially contribute to cerebral edema formation in stroke.
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Affiliation(s)
- Martha E O'Donnell
- Department of Physiology and Membrane Biology, University of California, One Shields Ave., Davis, CA 95616, USA.
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49
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Kahle KT, Rinehart J, Ring A, Gimenez I, Gamba G, Hebert SC, Lifton RP. WNK protein kinases modulate cellular Cl- flux by altering the phosphorylation state of the Na-K-Cl and K-Cl cotransporters. Physiology (Bethesda) 2006; 21:326-35. [PMID: 16990453 DOI: 10.1152/physiol.00015.2006] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Precise control of cellular Cl(-) transport is necessary for many fundamental physiological processes. For example, the intracellular concentration of Cl(-), fine-tuned through the coordinated action of cellular Cl(-) influx and efflux mechanisms, determines whether a neuron's response to GABA is excitatory or inhibitory. In epithelia, synchrony between apical and basolateral Cl(-) flux, and transcellular and paracellular Cl(-) transport, is necessary for efficient transepithelial Cl(-) reabsorption or secretion. In cells throughout the body, coordination of Cl(-) entry and exit mechanisms help defend against changes in cell volume. The Na-K-Cl and K-Cl cotransporters of the SLC12 gene family are important molecular determinants of Cl(-) entry and exit, respectively, in these systems. The WNK serine-threonine kinase family, members of which are mutated in an inherited form of human hypertension, are components of a signaling pathway that coordinates Cl(-) influx and efflux through SLC12 cotransporters to dynamically regulate intracellular Cl(-) activity.
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Affiliation(s)
- Kristopher T Kahle
- Howard Hughes Medical Institute, Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
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50
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Ivanova TI, Agalakova NI, Gusev GP. Activation of sodium transport in rat erythrocytes by inhibition of protein phosphatases 1 and 2A. Comp Biochem Physiol B Biochem Mol Biol 2006; 145:60-7. [PMID: 16875859 DOI: 10.1016/j.cbpb.2006.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 06/09/2006] [Accepted: 06/19/2006] [Indexed: 11/29/2022]
Abstract
Four structurally different protein phosphatases (PPs) inhibitors - fluoride, calyculin A, okadaic acid and cantharidin--were tested for their ability to modulate unidirectional Na(+) influx in rat red blood cells. Erythrocytes were incubated at 37 degrees C in isotonic and hypertonic media containing 1 mM ouabain and (22)Na in the absence or presence of PP inhibitors. Exposure of the cells to 20 mM fluoride or 50 nM calyculin A for 1 h under isosmotic conditions caused a significant stimulation of Na(+) influx, whereas addition of 200 microM cantharidin or 100 nM okadaic acid had no effect. After 2 h of treatment, however, all these PPs blockers significantly enhanced Na(+) transport in rat erythrocytes. Selective inhibitors of PP-1 and PP-2A types, calyculin A, cantharidin and okadaic acid, produced similar ( approximately 1.2-1.4-fold) stimulatory effects on Na(+) influx in the cells. Activation of Na(+) influx was unchanged with increasing calyculin A concentration from 50 to 200 nM. No additive stimulation of Na(+) influx was observed when the cells were treated with combination of 20 mM fluoride and 50 nM calyculin A. Na(+) influx induced by PPs blockers was inhibited by 1 mM amiloride and 200 muM bumetanide approximately in the equal extent, indicating the involvement of Na(+)/H(+) exchange and Na-K-2Cl cotransport in sodium transport through rat erythrocytes membrane. Activation of Na(+) transport in the cells induced by calyculin A and fluoride was associated with increase of intracellular Na(+) content. Shrinkage of the rat erythrocytes resulted in 2-fold activation of Na(+) influx. All tested PPs inhibitors additionally activated the Na(+) influx by 70-100% above basal shrinkage-induced level. Amiloride and bumetanide have diminished both the shrinkage-induced and PPs-inhibitors-induced Na(+) influxes. Thus, our observations clearly indicate that activities of Na(+)/H(+) exchanger and Na-K-2Cl cotransporter in rat erythrocytes are regulated by protein phosphatases and stimulated when protein dephosphorylation is inhibited.
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Affiliation(s)
- Tatiana I Ivanova
- Laboratory of Comparative Biochemistry of Inorganic Ions, Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 44 Thorez pr., 194223, St. Petersburg, Russia
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