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Reid MS, Kern DM, Brohawn SG. Cryo-EM structure of the potassium-chloride cotransporter KCC4 in lipid nanodiscs. eLife 2020; 9:e52505. [PMID: 32286222 PMCID: PMC7200160 DOI: 10.7554/elife.52505] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 04/12/2020] [Indexed: 01/24/2023] Open
Abstract
Cation-chloride-cotransporters (CCCs) catalyze transport of Cl- with K+ and/or Na+across cellular membranes. CCCs play roles in cellular volume regulation, neural development and function, audition, regulation of blood pressure, and renal function. CCCs are targets of clinically important drugs including loop diuretics and their disruption has been implicated in pathophysiology including epilepsy, hearing loss, and the genetic disorders Andermann, Gitelman, and Bartter syndromes. Here we present the structure of a CCC, the Mus musculus K+-Cl- cotransporter (KCC) KCC4, in lipid nanodiscs determined by cryo-EM. The structure, captured in an inside-open conformation, reveals the architecture of KCCs including an extracellular domain poised to regulate transport activity through an outer gate. We identify binding sites for substrate K+ and Cl- ions, demonstrate the importance of key coordinating residues for transporter activity, and provide a structural explanation for varied substrate specificity and ion transport ratio among CCCs. These results provide mechanistic insight into the function and regulation of a physiologically important transporter family.
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Affiliation(s)
- Michelle S Reid
- Department of Molecular and Cell Biology, University of California BerkeleyBerkeleyUnited States
- Helen Wills Neuroscience Institute, University of California BerkeleyBerkeleyUnited States
| | - David M Kern
- Department of Molecular and Cell Biology, University of California BerkeleyBerkeleyUnited States
- Helen Wills Neuroscience Institute, University of California BerkeleyBerkeleyUnited States
| | - Stephen Graf Brohawn
- Department of Molecular and Cell Biology, University of California BerkeleyBerkeleyUnited States
- Helen Wills Neuroscience Institute, University of California BerkeleyBerkeleyUnited States
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2
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Marcoux AA, Slimani S, Tremblay LE, Frenette-Cotton R, Garneau AP, Isenring P. Endocytic recycling of Na + -K + -Cl - cotransporter type 2: importance of exon 4. J Physiol 2019; 597:4263-4276. [PMID: 31216057 DOI: 10.1113/jp278024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 06/05/2019] [Indexed: 01/29/2023] Open
Abstract
KEY POINTS Na+ -K+ -Cl- cotransporter type 2 (NKCC2) is a 27-exon membrane protein that is expressed in the thick ascending limb (TAL) of Henle where it is involved in reabsorption of the ultrafiltered NaCl load. It comes as three splice variants that are identical to each other except for the residue composition of exon 4 and that differ in their transport characteristics, functional roles and distributions along the TAL. In this report, it is shown that the variants also differ in their trafficking properties and that two residues in exon 4 play a key role in this regard. One of these residues was also shown to sustain carrier internalization. Through these results, a novel function for the alternatively spliced exon of NKCC2 has been identified and a domain that is involved in carrier trafficking has been uncovered for the first time in a cation-Cl- cotransporter family member. ABSTRACT Na+ -K+ -Cl- cotransporter type 2 (NKCC2) is a 12-transmembrane (TM) domain cell surface glycoprotein that is expressed in the thick ascending limb (TAL) of Henle and stimulated during cell shrinkage. It comes as three splice variants (A, B and F) that are identical to each other except for TM2 and the following connecting segment (CS2). Yet, these variants do not share the same localization, transport characteristics and physiological roles along the TAL. We have recently found that while cell shrinkage could exert its activating effect by increasing NKCC2 expression at the cell surface, the variants also responded differentially to this stimulus. In the current work, a mutagenic approach was exploited to determine whether CS2 could play a role in carrier trafficking and identify the residues potentially involved. We found that when the residue of position 238 in NKCC2A (F) and NKCC2B (Y) was replaced by the corresponding residue in NKCC2F (V), carrier activity increased by over 3-fold and endocytosis decreased concomitantly. We also found that when the residue of position 230 in NKCC2F (M) was replaced by the one in NKCC2B (T), carrier activity and affinity for ions both increased substantially whereas expression at the membrane decreased. Taken together, these results suggest that CS2 is involved in carrier trafficking and that two of its residues, those of positions 238 and 230, are part of an internalization motif. They also indicate that the divergent residue of position 230 plays the dual role of specifying ion affinity and sustaining carrier internalization.
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Affiliation(s)
- Andrée-Anne Marcoux
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University, Québec, QC, Canada, G1R 2J6
| | - Samira Slimani
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University, Québec, QC, Canada, G1R 2J6
| | - Laurence E Tremblay
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University, Québec, QC, Canada, G1R 2J6
| | - Rachelle Frenette-Cotton
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University, Québec, QC, Canada, G1R 2J6
| | - Alexandre P Garneau
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University, Québec, QC, Canada, G1R 2J6.,Cardiometabolic Research Group, Department of Kinesiology, Faculty of Medicine, University of Montréal, Montréal, QC, Canada, H3T 1J4
| | - Paul Isenring
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University, Québec, QC, Canada, G1R 2J6
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3
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Marcoux AA, Slimani S, Tremblay LE, Frenette-Cotton R, Garneau AP, Isenring P. Regulation of Na +-K +-Cl - cotransporter type 2 by the with no lysine kinase-dependent signaling pathway. Am J Physiol Cell Physiol 2019; 317:C20-C30. [PMID: 30917032 DOI: 10.1152/ajpcell.00041.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Na+-K+-Cl- cotransporter type 2 (NKCC2) is confined to the apical membrane of the thick ascending limb of Henle, where it reabsorbs a substantial fraction of the ultrafiltered NaCl load. It is expressed along this nephron segment as three main splice variants (called NKCC2A, NKCC2B, and NKCC2F) that differ in residue composition along their second transmembrane domain and first intracellular cytosolic connecting segment (CS2). NKCC2 is known to be activated by cell shrinkage and intracellular [Cl-] reduction. Although the with no lysine (WNK) kinases could play a role in this response, the mechanisms involved are ill defined, and the possibility of variant-specific responses has not been tested thus far. In this study, we have used the Xenopus laevis oocyte expression system to gain further insight in these regards. We have found for the first time that cell shrinkage could stimulate NKCC2A- and NKCC2B-mediated ion transport by increasing carrier abundance at the cell surface and that this response was achieved (at least in part) by the enzymatic function of a WNK kinase. Interestingly, we have also found that the activity and cell surface abundance of NKCC2F were less affected by cell shrinkage compared with the other variants and that ion transport by certain variants could be stimulated through WNK kinase expression in the absence of carrier redistribution. Taken together, these results suggest that the WNK kinase-dependent pathway can affect both the trafficking as well as intrinsic activity of NKCC2 and that CS2 plays an important role in carrier regulation.
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Affiliation(s)
- Andrée-Anne Marcoux
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University , Quebec City, Quebec , Canada
| | - Samira Slimani
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University , Quebec City, Quebec , Canada
| | - Laurence E Tremblay
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University , Quebec City, Quebec , Canada
| | - Rachelle Frenette-Cotton
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University , Quebec City, Quebec , Canada
| | - Alexandre P Garneau
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University , Quebec City, Quebec , Canada.,Cardiometabolic Research Group, Department of Kinesiology, Faculty of Medicine, University of Montreal , Montreal, Quebec , Canada
| | - Paul Isenring
- Nephrology Research Group, L'Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Laval University , Quebec City, Quebec , Canada
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4
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Garneau AP, Marcoux AA, Slimani S, Tremblay LE, Frenette-Cotton R, Mac-Way F, Isenring P. Physiological roles and molecular mechanisms of K + -Cl - cotransport in the mammalian kidney and cardiovascular system: where are we? J Physiol 2019; 597:1451-1465. [PMID: 30659612 DOI: 10.1113/jp276807] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 12/07/2018] [Indexed: 11/08/2022] Open
Abstract
In the early 80s, renal microperfusion studies led to the identification of a basolateral K+ -Cl- cotransport mechanism in the proximal tubule, thick ascending limb of Henle and collecting duct. More than ten years later, this mechanism was found to be accounted for by three different K+ -Cl- cotransporters (KCC1, KCC3 and KCC4) that are differentially distributed along the renal epithelium. Two of these isoforms (KCC1 and KCC3) were also found to be expressed in arterial walls, the myocardium and a variety of neurons. Subsequently, valuable insights have been gained into the molecular and physiological properties of the KCCs in both the mammalian kidney and cardiovascular system. There is now robust evidence indicating that KCC4 sustains distal renal acidification and that KCC3 regulates myogenic tone in resistance vessels. However, progress in understanding the functional significance of these transporters has been slow, probably because each of the KCC isoforms is not identically distributed among species and some of them share common subcellular localizations with other KCC isoforms or sizeable conductive Cl- pathways. In addition, the mechanisms underlying the process of K+ -Cl- cotransport are still ill defined. The present review focuses on the knowledge gained regarding the roles and properties of KCCs in renal and cardiovascular tissues.
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Affiliation(s)
- A P Garneau
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6.,Cardiometabolic Axis, School of Kinesiology and Physical Activity Sciences, Montreal University, 900, rue Saint-Denis, Montréal, (Qc) H2X 0A9
| | - A A Marcoux
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - S Slimani
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - L E Tremblay
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - R Frenette-Cotton
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - F Mac-Way
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
| | - P Isenring
- Nephrology Research Group, Department of Medicine, Laval University, 11, côte du Palais, Québec (Qc), Canada, G1R 2J6
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5
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Frenette-Cotton R, Marcoux AA, Garneau AP, Noel M, Isenring P. Phosphoregulation of K + -Cl - cotransporters during cell swelling: Novel insights. J Cell Physiol 2018; 233:396-408. [PMID: 28276587 DOI: 10.1002/jcp.25899] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 03/06/2017] [Indexed: 01/21/2023]
Abstract
The K+ -Cl- cotransporters (KCCs) belong to the cation-Cl- cotransporter family and consist of four isoforms and many splice variants. Their main role is to promote electroneutral efflux of K+ and Cl- ions across the surface of many cell types and, thereby, to regulate intracellular ion concentration, cell volume, and epithelial salt movement. These transport systems are induced by an increase in cell volume and are less active at lower intracellular [Cl- ] (Cli ), but the mechanisms at play are still ill-defined. In this work, we have exploited the Xenopus laevis expression system to study the role of lysine-deficient protein kinases (WNKs), protein phosphatases 1 (PP1s), and SPS1-related proline/alanine-rich kinase (SPAK) in KCC4 regulation during cell swelling. We have found that WNK4 and PP1 regulate KCC4 activity as part of a common signaling module, but that they do not exert their effects through SPAK or carrier dephosphorylation. We have also found that the phosphatases at play include PP1α and PP1γ1, but that WNK4 acts directly on the PP1s instead of the opposite. Unexpectedly, however, both cell swelling and a T926A substitution in the C-terminus of full-length KCC4 led to higher levels of heterologous K+ -Cl- cotransport and overall carrier phosphorylation. These results imply that the response to cell swelling must also involve allosteric-sensitive kinase-dependent phosphoacceptor sites in KCC4. They are thus partially inconsistent with previous models of KCC regulation.
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Affiliation(s)
| | - Andrée-Anne Marcoux
- Nephrology Research Group, Department of Medicine, Laval University, Québec, Québec, Canada
| | - Alexandre P Garneau
- Nephrology Research Group, Department of Medicine, Laval University, Québec, Québec, Canada
| | - Micheline Noel
- Nephrology Research Group, Department of Medicine, Laval University, Québec, Québec, Canada
| | - Paul Isenring
- Nephrology Research Group, Department of Medicine, Laval University, Québec, Québec, Canada
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6
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Lee KP, Kim HJ, Yang D. Functional identification of protein phosphatase 1-binding consensus residues in NBCe1-B. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2017; 22:91-99. [PMID: 29302216 PMCID: PMC5746516 DOI: 10.4196/kjpp.2018.22.1.91] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/06/2017] [Accepted: 11/19/2017] [Indexed: 12/03/2022]
Abstract
Protein phosphatase 1 (PP1) is involved in various signal transduction mechanisms as an extensive regulator. The PP1 catalytic subunit (PP1c) recognizes and binds to PP1-binding consensus residues (FxxR/KxR/K) in NBCe1-B. Consequently, we focused on identifying the function of the PP1-binding consensus residue, 922FMDRLK927, in NBCe1-B. Using site-directed mutagenesis and co-immunoprecipitation assays, we revealed that in cases where the residues were substituted (F922A, R925A, and K927A) or deleted (deletion of amino acids 922–927), NBCe1-B mutants inhibited PP1 binding to NBCe1-B. Additionally, by recording the intracellular pH, we found that PP1-binding consensus residues in NBCe1-B were not only critical for NBCe1-B activity, but also relevant to its surface expression level. Therefore, we reported that NBCe1-B, as a substrate of PP1, contains these residues in the C-terminal region and that the direct interaction between NBCe1-B and PP1 is functionally critical in controlling the regulation of the HCO3− transport. These results suggested that like IRBIT, PP1 was another novel regulator of HCO3− secretion in several types of epithelia.
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Affiliation(s)
- Kyu Pil Lee
- Laboratory of Physiology, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea
| | - Hyun Jin Kim
- Department of Physiology, School of Medicine, Sungkyunkwan University, Suwon 16419, Korea
| | - Dongki Yang
- Department of Physiology, College of Medicine, Gachon University, Incheon 21999, Korea
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7
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Garneau AP, Marcoux AA, Frenette-Cotton R, Mac-Way F, Lavoie JL, Isenring P. Molecular insights into the normal operation, regulation, and multisystemic roles of K +-Cl - cotransporter 3 (KCC3). Am J Physiol Cell Physiol 2017; 313:C516-C532. [PMID: 28814402 DOI: 10.1152/ajpcell.00106.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 07/26/2017] [Accepted: 08/14/2017] [Indexed: 12/12/2022]
Abstract
Long before the molecular identity of the Na+-dependent K+-Cl- cotransporters was uncovered in the mid-nineties, a Na+-independent K+-Cl- cotransport system was also known to exist. It was initially observed in sheep and goat red blood cells where it was shown to be ouabain-insensitive and to increase in the presence of N-ethylmaleimide (NEM). After it was established between the early and mid-nineties, the expressed sequence tag (EST) databank was found to include a sequence that was highly homologous to those of the Na+-dependent K+-Cl- cotransporters. This sequence was eventually found to code for the Na+-independent K+-Cl- cotransport function that was described in red blood cells several years before. It was termed KCC1 and led to the discovery of three isoforms called KCC2, KCC3, and KCC4. Since then, it has become obvious that each one of these isoforms exhibits unique patterns of distribution and fulfills distinct physiological roles. Among them, KCC3 has been the subject of great attention in view of its important role in the nervous system and its association with a rare hereditary sensorimotor neuropathy (called Andermann syndrome) that affects many individuals in Quebec province (Canada). It was also found to play important roles in the cardiovascular system, the organ of Corti, and circulating blood cells. As will be seen in this review, however, there are still a number of uncertainties regarding the transport properties, structural organization, and regulation of KCC3. The same is true regarding the mechanisms by which KCC3 accomplishes its numerous functions in animal cells.
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Affiliation(s)
- A P Garneau
- Nephrology Research Group, Department of Medicine, Laval University, Quebec City, Quebec, Canada; and
- Cardiometabolic Axis, Kinesiology Department, University of Montréal, Montreal, Quebec, Canada
| | - A A Marcoux
- Nephrology Research Group, Department of Medicine, Laval University, Quebec City, Quebec, Canada; and
| | - R Frenette-Cotton
- Nephrology Research Group, Department of Medicine, Laval University, Quebec City, Quebec, Canada; and
| | - F Mac-Way
- Nephrology Research Group, Department of Medicine, Laval University, Quebec City, Quebec, Canada; and
| | - J L Lavoie
- Cardiometabolic Axis, Kinesiology Department, University of Montréal, Montreal, Quebec, Canada
| | - P Isenring
- Nephrology Research Group, Department of Medicine, Laval University, Quebec City, Quebec, Canada; and
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8
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Molecular features and physiological roles of K +-Cl - cotransporter 4 (KCC4). Biochim Biophys Acta Gen Subj 2017; 1861:3154-3166. [PMID: 28935604 DOI: 10.1016/j.bbagen.2017.09.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/15/2017] [Indexed: 12/27/2022]
Abstract
A K+-Cl- cotransport system was documented for the first time during the mid-seventies in sheep and goat red blood cells. It was then described as a Na+-independent and ouabain-insensitive ion carrier that could be stimulated by cell swelling and N-ethylmaleimide (NEM), a thiol-reacting agent. Twenty years later, this system was found to be dispensed by four different isoforms in animal cells. The first one was identified in the expressed sequence tag (EST) database by Gillen et al. based on the assumption that it would be homologous to the Na+-dependent K+-Cl- cotransport system for which the molecular identity had already been uncovered. Not long after, the three other isoforms were once again identified in the EST databank. Among those, KCC4 has generated much interest a few years ago when it was shown to sustain distal renal acidification and hearing development in mouse. As will be seen in this review, many additional roles were ascribed to this isoform, in keeping with its wide distribution in animal species. However, some of them have still not been confirmed through animal models of gene inactivation or overexpression. Along the same line, considerable knowledge has been acquired on the mechanisms by which KCC4 is regulated and the environmental cues to which it is sensitive. Yet, it is inferred to some extent from historical views and extrapolations.
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9
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Garneau AP, Carpentier GA, Marcoux AA, Frenette-Cotton R, Simard CF, Rémus-Borel W, Caron L, Jacob-Wagner M, Noël M, Powell JJ, Bélanger R, Côté F, Isenring P. Aquaporins Mediate Silicon Transport in Humans. PLoS One 2015; 10:e0136149. [PMID: 26313002 PMCID: PMC4551902 DOI: 10.1371/journal.pone.0136149] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 07/31/2015] [Indexed: 01/15/2023] Open
Abstract
In animals, silicon is an abundant and differentially distributed trace element that is believed to play important biological functions. One would thus expect silicon concentrations in body fluids to be regulated by silicon transporters at the surface of many cell types. Curiously, however, and even though they exist in plants and algae, no such transporters have been identified to date in vertebrates. Here, we show for the first time that the human aquaglyceroporins, i.e., AQP3, AQP7, AQP9 and AQP10 can act as silicon transporters in both Xenopus laevis oocytes and HEK-293 cells. In particular, heterologously expressed AQP7, AQP9 and AQP10 are all able to induce robust, saturable, phloretin-sensitive silicon transport activity in the range that was observed for low silicon rice 1 (lsi1), a silicon transporter in plant. Furthermore, we show that the aquaglyceroporins appear as relevant silicon permeation pathways in both mice and humans based on 1) the kinetics of substrate transport, 2) their presence in tissues where silicon is presumed to play key roles and 3) their transcriptional responses to changes in dietary silicon. Taken together, our data provide new evidence that silicon is a potentially important biological element in animals and that its body distribution is regulated. They should open up original areas of investigations aimed at deciphering the true physiological role of silicon in vertebrates.
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Affiliation(s)
- Alexandre P. Garneau
- L’Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
| | - Gabriel A. Carpentier
- L’Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
| | - Andrée-Anne Marcoux
- L’Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
| | - Rachelle Frenette-Cotton
- L’Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
| | - Charles F. Simard
- L’Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
| | - Wilfried Rémus-Borel
- Department of Phytology, Faculty of Sciences of Agriculture and Alimentation, Laval Université Laval, Québec City, Québec, Canada
| | - Luc Caron
- L’Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
| | - Mariève Jacob-Wagner
- L’Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
| | - Micheline Noël
- L’Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
| | - Jonathan J. Powell
- Medical Research Council Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, United Kingdom
| | - Richard Bélanger
- Department of Phytology, Faculty of Sciences of Agriculture and Alimentation, Laval Université Laval, Québec City, Québec, Canada
| | - François Côté
- L’Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
| | - Paul Isenring
- L’Hôtel-Dieu de Québec Research Center, Department of Medicine, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
- * E-mail:
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10
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Arroyo JP, Kahle KT, Gamba G. The SLC12 family of electroneutral cation-coupled chloride cotransporters. Mol Aspects Med 2013; 34:288-98. [PMID: 23506871 DOI: 10.1016/j.mam.2012.05.002] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 04/09/2012] [Indexed: 11/21/2022]
Abstract
The SLC12 family encodes electroneutral cation-coupled chloride cotransporters that are critical for several physiological processes including cell volume regulation, modulation of intraneuronal chloride concentration, transepithelial ion movement, and blood pressure regulation. Members of this family are the targets of the most commonly used diuretic drugs, have been shown to be the causative genes for inherited disease such as Gitelman, Bartter and Andermann syndromes, and potentially play a role in polygenic complex diseases like arterial hypertension, epilepsy, osteoporosis, and cancer.
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Affiliation(s)
- Juan Pablo Arroyo
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico
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11
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Park S, Hong JH, Ohana E, Muallem S. The WNK/SPAK and IRBIT/PP1 pathways in epithelial fluid and electrolyte transport. Physiology (Bethesda) 2013; 27:291-9. [PMID: 23026752 DOI: 10.1152/physiol.00028.2012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fluid and electrolyte homeostasis is a fundamental physiological function required for survival and is associated with a plethora of diseases when aberrant. Systemic fluid and electrolyte composition is regulated by the kidney, and all secretory epithelia generate biological fluids with defined electrolyte composition by vectorial transport of ions and the obligatory water. A major regulatory pathway that immerged in the last several years is regulation of ion transporters by the WNK/SPAK kinases and IRBIT/PP1 pathways. The IRBIT/PP1 pathway functions to reverse the effects of the WNK/SPAK kinases pathway, as was demonstrated for NBCe1-B and CFTR. Since many transporters involved in fluid and electrolyte homeostasis are affected by PP1 and/or calcineurin, it is possible that WNK/SPAK and IRBIT/PP1 form a common regulatory pathway to tune the activity of fluid and electrolyte transport in response to physiological demands.
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Affiliation(s)
- Seonghee Park
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland, USA
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12
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Cruz-Rangel S, Gamba G, Ramos-Mandujano G, Pasantes-Morales H. Influence of WNK3 on intracellular chloride concentration and volume regulation in HEK293 cells. Pflugers Arch 2012; 464:317-30. [PMID: 22864523 DOI: 10.1007/s00424-012-1137-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 07/06/2012] [Accepted: 07/07/2012] [Indexed: 01/17/2023]
Abstract
The involvement of WNK3 (with no lysine [K] kinase) in cell volume regulation evoked by anisotonic conditions was investigated in two modified stable lines of HEK293 cells: WNK3+, overexpressing WNK3 and WNK3-KD expressing a kinase inactive by a punctual mutation (D294A) at the catalytic site. This different WNK3 functional expression modified intracellular Cl(-) concentration with the following profile: WNK3+ > control > WNK3-KD cells. Stimulated with 15% hypotonic solutions, WNK3+ cells showed less efficient RVD (13.1%), lower Cl(-) efflux and decreased (94.5%) KCC activity. WNK3-KD cells showed 30.1% more efficient RVD, larger Cl(-) efflux and 5-fold higher KCC activity, increased since the isotonic condition. Volume-sensitive Cl(-) currents were similar in controls, WNK3+ cells, and WNK3-KD cells. Taurine efflux was not evoked at H15%. These results show a WNK3 influence on RVD in HEK293 cells via increasing KCC activity. Hypertonic medium induced cell shrinkage and RVI. In both WNK3+ and WNK3-KD cells, RVI and NKCC activity were increased, in WNK3+ cells presumably by enhanced NKCC phosphorylation, and in WNK3-KD cells via the [Cl(-)](i) reduction induced by the higher KCC activity in characteristic of these cells. These results support the role of WNK3 in modulation of intracellular Cl(-) concentration, in RVD, and indirectly on RVI, via its effects on KCC and NKCC activity. WNK3 in HEK293 cells is expressed as puncta at the intercellular junctions and diffusely at the cytosol, while the inactive kinase was found concentrated at the Golgi area. Cells with inactive WNK3 exhibited a marked change of cell phenotype.
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Affiliation(s)
- Silvia Cruz-Rangel
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, Circuito Exterior, 04510, Mexico, DF, Mexico
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Acton BA, Mahadevan V, Mercado A, Uvarov P, Ding Y, Pressey J, Airaksinen MS, Mount DB, Woodin MA. Hyperpolarizing GABAergic transmission requires the KCC2 C-terminal ISO domain. J Neurosci 2012; 32:8746-51. [PMID: 22723714 PMCID: PMC3395202 DOI: 10.1523/jneurosci.6089-11.2012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 05/10/2012] [Accepted: 05/11/2012] [Indexed: 11/21/2022] Open
Abstract
KCC2 is the neuron-specific member of the of K(+)-Cl(-) cotransporter gene family. It is also the only member of its family that is active under physiologically normal conditions, in the absence of osmotic stress. By extruding Cl(-) from the neuron under isotonic conditions, this transporter maintains a low concentration of neuronal Cl(-), which is essential for fast inhibitory synaptic transmission by GABA and glycine in the mature nervous system. The other members of this K(+)-Cl(-) cotransporter gene family are exclusively swelling-activated. Here we demonstrate that a 15 aa region near the end of the C terminus, unique to KCC2 (termed the ISO domain), is required for KCC2 to cotransport K(+) and Cl(-) out of the neuron under isotonic conditions. We made this discovery by overexpressing chimeric KCC2-KCC4 cDNA constructs in cultured hippocampal neurons prepared from Sprague Dawley rat embryos and assaying neuronal Cl(-) through gramicidin perforated patch-clamp recordings. We found that when neurons had been transfected with a chimeric KCC2 that lacked the unique ISO domain, hyperpolarizing responses to GABA were abolished. This finding indicates that the ISO domain is required for neuronal Cl(-) regulation. Furthermore, we discovered that when KCC2 lacks the ISO domain, it still retains swelling-activated transport, which demonstrates that there are exclusive molecular determinants of isotonic and swelling-induced K(+)-Cl(-) cotransport in neurons.
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Affiliation(s)
- Brooke A. Acton
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5
| | - Vivek Mahadevan
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5
| | - Adrianna Mercado
- Renal Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115
- Departamento de Nefrología, Instituto Nacional de Cardiología Ignacio Chávez, 14080 Mexico City, Mexico
| | - Pavel Uvarov
- Neuroscience Center and Institute of Biomedicine, University of Helsinki, FIN-00014 Helsinki, Finland, and
| | - Yanli Ding
- Renal Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Jessica Pressey
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5
| | - Matti S. Airaksinen
- Neuroscience Center and Institute of Biomedicine, University of Helsinki, FIN-00014 Helsinki, Finland, and
| | - David B. Mount
- Renal Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115
- Renal Division, Veterans Affairs Boston Healthcare System, Harvard Medical School, West Roxbury, Massachusetts 02132
| | - Melanie A. Woodin
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5
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Frog oocytes to unveil the structure and supramolecular organization of human transport proteins. PLoS One 2011; 6:e21901. [PMID: 21760919 PMCID: PMC3131388 DOI: 10.1371/journal.pone.0021901] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 06/08/2011] [Indexed: 11/19/2022] Open
Abstract
Structural analyses of heterologously expressed mammalian membrane proteins remain a great challenge given that microgram to milligram amounts of correctly folded and highly purified proteins are required. Here, we present a novel method for the expression and affinity purification of recombinant mammalian and in particular human transport proteins in Xenopus laevis frog oocytes. The method was validated for four human and one murine transporter. Negative stain transmission electron microscopy (TEM) and single particle analysis (SPA) of two of these transporters, i.e., the potassium-chloride cotransporter 4 (KCC4) and the aquaporin-1 (AQP1) water channel, revealed the expected quaternary structures within homogeneous preparations, and thus correct protein folding and assembly. This is the first time a cation-chloride cotransporter (SLC12) family member is isolated, and its shape, dimensions, low-resolution structure and oligomeric state determined by TEM, i.e., by a direct method. Finally, we were able to grow 2D crystals of human AQP1. The ability of AQP1 to crystallize was a strong indicator for the structural integrity of the purified recombinant protein. This approach will open the way for the structure determination of many human membrane transporters taking full advantage of the Xenopus laevis oocyte expression system that generally yields robust functional expression.
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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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