51
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McCormick JA, Yang CL, Ellison DH. WNK kinases and renal sodium transport in health and disease: an integrated view. Hypertension 2008; 51:588-96. [PMID: 18212265 DOI: 10.1161/hypertensionaha.107.103788] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- James A McCormick
- Division of Nephrology and Hypertension and Heart Research Center, Department of Medicine, Oregon Health and Science University, Portland, OR 97239, USA
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52
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Abstract
Point mutations in WNK4 [for With No K (lysine)], a serine-threonine kinase that is expressed in the distal nephron of the kidney, are linked to familial hyperkalemic hypertension (FHH). The imbalanced electrolyte homeostasis in FHH has led to studies toward an understanding of WNK4-mediated regulation of ion transport proteins in the kidney. A growing number of ion transport proteins for Na(+), K(+), Ca(2+), and Cl(-), including ion channels and transporters in the transcellular pathway and claudins in the paracellular pathway, are shown to be regulated by WNK4 from studies using models ranging from Xenopus laevis oocytes to transgenic and knockin mice. WNK4 regulates these transport proteins in different directions and by different cellular mechanisms. The common theme of WNK4-mediated regulation is to alter the abundance of ion transport proteins at the plasma membrane, with the exception of claudins, which are phosphorylated in the presence of WNK4. The regulation of WNK4 can be blocked by the full-length WNK1, whose action is in turn antagonized by a kidney-specific WNK1 variant lacking the kinase domain. In addition, WNK4 also activates stress-related serine-threonine kinases to regulate members of the SLC12 family members of cation-chloride cotransporters. In many cases, the FHH-causing mutants of WNK4 exhibit differences from wild-type WNK4 in regulating ion transport proteins. These regulations well explain the clinical features of FHH and provide insights into the multilayered regulation of ion transport processes in the distal nephron.
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Affiliation(s)
- Ji-Bin Peng
- Nephrology Research and Training Center, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-0006, USA.
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53
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Choe KP, Strange K. Evolutionarily conserved WNK and Ste20 kinases are essential for acute volume recovery and survival after hypertonic shrinkage in Caenorhabditis elegans. Am J Physiol Cell Physiol 2007; 293:C915-27. [PMID: 17596296 DOI: 10.1152/ajpcell.00126.2007] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Members of the germinal center kinase (GCK)-VI subfamily of Ste20 kinases regulate a Caenorhabditis elegans ClC anion channel and vertebrate SLC12 cation-Cl(-) cotransporters. With no lysine (K) (WNK) protein kinases interact with and activate the mammalian GCK-VI kinases proline-alanine-rich Ste20-related kinase (PASK) and oxidative stress-responsive 1 (OSR1). We demonstrate here for the first time that GCK-VI kinases play an essential role in whole animal osmoregulation. RNA interference (RNAi) knockdown of the single C. elegans GCK-VI kinase, GCK-3, dramatically inhibits systemic volume recovery and survival after hypertonic shrinkage. Tissue-specific RNAi suggests that GCK-3 functions primarily in the hypodermis and intestine to mediate volume recovery. The single C. elegans WNK kinase, WNK-1, binds to GCK-3, and wnk-1 knockdown gives rise to a phenotype qualitatively similar to that of gck-3(RNAi) worms. Knockdown of the two kinases together has no additive effect, suggesting that WNK-1 and GCK-3 function in a common pathway. We postulate that WNK-1 functions upstream of GCK-3 in a manner similar to that postulated for its mammalian homologs. Phylogenetic analysis of kinase functional domains suggests that the interaction between GCK-VI and WNK kinases first occurred in an early metazoan and therefore likely coincided with the need of multicellular animals to tightly regulate transepithelial transport processes that mediate systemic osmotic homeostasis.
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Affiliation(s)
- Keith P Choe
- Vanderbilt Univ. Medical Center, T-4202 Medical Center North, Nashville, TN 37232-2520, USA
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54
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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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55
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Yang CL, Liu X, Paliege A, Zhu X, Bachmann S, Dawson DC, Ellison DH. WNK1 and WNK4 modulate CFTR activity. Biochem Biophys Res Commun 2006; 353:535-40. [PMID: 17194447 DOI: 10.1016/j.bbrc.2006.11.151] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Accepted: 11/15/2006] [Indexed: 11/26/2022]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is an ATP-gated chloride channel. WNK kinases are widely expressed modulators of ion transport. WNK1 and WNK4, two WNK kinases that are mutated in familial hyperkalemic hypertension (FHHt), are co-expressed with CFTR in several organs, raising the possibility that WNK kinases might alter CFTR activity in vivo or that CFTR could be involved in the pathogenesis of FHHt. Here, we report that WNK1 co-localizes with CFTR protein in pulmonary epithelial cells. Co-expression of WNK1 or WNK4 with CFTR in Xenopus laevis oocytes suppresses chloride channel activity. The effect of WNK4 is dose dependent and occurs, at least in part, by reducing CFTR protein abundance at the plasma membrane. This effect is independent of WNK4 kinase activity. In contrast, the effect of WNK1 on CFTR activity requires intact WNK1 kinase activity. Moreover WNK1 and WNK4 exhibit additive CFTR inhibition. Previous reports suggest that patients with FHHt exhibit mild changes in nasal potential difference that resemble the more severe changes that occur in cystic fibrosis. We report that the FHHt-causing mutant WNK4 Q562E is a more potent inhibitor of CFTR activity than is the wild-type WNK4. Taken together, these results suggest that WNK1 and WNK4 may modulate CFTR activity; they further suggest that WNK kinases may be potential therapeutic targets for cystic fibrosis.
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Affiliation(s)
- Chao-Ling Yang
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA.
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56
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Garovic VD, Hilliard AA, Turner ST. Monogenic forms of low-renin hypertension. ACTA ACUST UNITED AC 2006; 2:624-30. [PMID: 17066054 DOI: 10.1038/ncpneph0309] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Accepted: 07/26/2006] [Indexed: 12/29/2022]
Abstract
Hypertension is an important public health problem affecting more than 50 million individuals in the US alone. The most common form, essential hypertension, results from the complex interplay between genetic predisposition and environmental influences. In contrast, monogenic (mendelian) forms of hypertension are caused by single gene mutations that are influenced little, if at all, by environmental factors. Most monogenic forms of hypertension affect either electrolyte transport in the distal nephron, or the synthesis or activity of mineralocorticoid hormones, leading to the common pathogenic mechanisms of increased distal tubular reabsorption of sodium and chloride, volume expansion and hypertension. In young patients with a family history of hypertension who present with severe or refractory hypertension and characteristic hormonal and biochemical abnormalities, the differential diagnosis should include monogenic forms of hypertension. Genetic testing, which is increasingly available, can facilitate timely diagnosis and treatment of these relatively uncommon disorders, such that the underlying defect can be corrected or ameliorated and the long-term consequences of poorly controlled hypertension prevented.
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Affiliation(s)
- Vesna D Garovic
- Division of Nephrology and Hypertension, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
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57
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Proctor G, Linas S. Type 2 pseudohypoaldosteronism: new insights into renal potassium, sodium, and chloride handling. Am J Kidney Dis 2006; 48:674-93. [PMID: 16997066 DOI: 10.1053/j.ajkd.2006.06.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Accepted: 06/12/2006] [Indexed: 11/11/2022]
Affiliation(s)
- Gregory Proctor
- Division of Nephrology, University of Colorado Health Sciences Center, Denver, CO, USA.
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58
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Sun X, Gao L, Yu RK, Zeng G. Down-regulation of WNK1 protein kinase in neural progenitor cells suppresses cell proliferation and migration. J Neurochem 2006; 99:1114-21. [PMID: 17018027 DOI: 10.1111/j.1471-4159.2006.04159.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
WNK1, a Ser/Thr protein kinase, is widely expressed in many tissues. Its biological functions are largely unknown. Disruption of the WNK1 gene in mice leads to embryonic lethality at day 13, implicating a critical role of WNK1 in embryonic development. To investigate this potential function, we used antisense strategy to knock down the expression of WNK1 in a mouse neural progenitor cell line, C17.2. Down-regulation of WNK1 in C17.2 cells greatly reduced cell growth. Addition of epidermal growth factor (EGF), a mitogen for C17.2 cells, had no effect on growth. The WNK1-knockdown cells showed a flat and rounded morphology, characteristic of the immature and non-differentiated phenotype of the progenitor cells; this was further demonstrated by immunostaining for the progenitor and neuronal markers. Migration of the WNK1-knockdown C17.2 cells was reduced as tested in culture dishes or Matrigel-covered chambers. Moreover, activation of extracellular signal-regulated kinase (ERK1)/2 and ERK5 by EGF in the WNK1-knockdown cells was suppressed. These results demonstrate a novel function of WNK1 in proliferation, migration, and differentiation of neural progenitor cells, likely by mechanisms involving activation of the mitogen-activated protein (MAP) kinase ERK1/2 and/or ERK5 pathways.
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Affiliation(s)
- Xutong Sun
- Developmental Neurobiology Program, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, Georgia 30912, USA.
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59
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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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60
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Delaloy C, Hadchouel J, Imbert-Teboul M, Clemessy M, Houot AM, Jeunemaitre X. Cardiovascular expression of the mouse WNK1 gene during development and adulthood revealed by a BAC reporter assay. THE AMERICAN JOURNAL OF PATHOLOGY 2006; 169:105-18. [PMID: 16816365 PMCID: PMC1698764 DOI: 10.2353/ajpath.2006.051290] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Large deletions in WNK1 are associated with inherited arterial hypertension. WNK1 encodes two types of protein: a kidney-specific isoform (KS-WNK1) lacking kinase activity and a ubiquitously expressed full-length isoform (L-WNK1) with serine threonine kinase activity. Disease is thought to result from hypermorphic mutations increasing the production of one or both isoforms. However, the pattern of L-WNK1 expression remains poorly characterized. We generated transgenic mice bearing a murine WNK1 BAC containing the nlacZ reporter gene for monitoring L-WNK1 expression during development and adulthood. We observed previously unsuspected early expression in the vessels and primitive heart during embryogenesis, consistent with the early death of WNK1(-/-) mice. The generalized cardiovascular expression observed in adulthood may also suggest a possible kidney-independent role in blood pressure regulation. The second unsuspected site of L-WNK1 expression was the granular layer and Purkinje cells of the cerebellum, suggesting a role in local ion balance or cell trafficking. In the kidney, discordance between endogenous L-WNK1 and transgene expression suggests that either cis-regulatory elements important for physiological renal expression lie outside the BAC sequence or that illegitimate interactions occur between promoters. Despite this limitation, this transgenic model is a potentially valuable tool for the analysis of spatial and temporal aspects of WNK1 expression and regulation.
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61
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Abstract
The kidney plays a central role in our ability to maintain an appropriate sodium balance, which is critical for the determination of blood pressure. The kidney's capacity for salt conservation may not be widely appreciated, and in general we consume vastly more salt than we need. Here we consider the socioeconomics of salt consumption, outline current knowledge of renal salt handling at the molecular level, describe some of the disease entities associated with abnormal sodium handling, give an overview of some of the animal models and their relevance to human disease, and examine the evidence that lowering our salt intake can help combat hypertension and cardiovascular disease.
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62
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Cope G, Murthy M, Golbang AP, Hamad A, Liu CH, Cuthbert AW, O'Shaughnessy KM. WNK1 Affects Surface Expression of the ROMK Potassium Channel Independent of WNK4. J Am Soc Nephrol 2006; 17:1867-74. [PMID: 16775035 DOI: 10.1681/asn.2005111224] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The WNK (with no lysine kinase) kinases are a novel class of serine/threonine kinases that lack a characteristic lysine residue for ATP docking. Both WNK1 and WNK4 are expressed in the mammalian kidney, and mutations in either can cause the rare familial syndrome of hypertension and hyperkalemia (Gordon syndrome, or pseudohypoaldosteronism type 2). The molecular basis for the action of WNK4 is through alteration in the membrane expression of the NaCl co-transporter (NCCT) and the renal outer-medullary K channel KCNJ1 (ROMK). The actions of WNK1 are less well defined, and evidence to date suggests that it can affect NCCT expression but only in the presence of WNK4. The results of co-expressing WNK1 with ROMK in Xenopus oocytes are reported for the first time. These studies show that WNK1 is able to suppress total current directly through ROMK by causing a marked reduction in its surface expression. The effect is mimicked by a kinase-dead mutant of WNK1 (368D > A), suggesting that it is not dependent on its catalytic activity. Study of the time course of ROMK expression further suggests that WNK1 accelerates trafficking of ROMK from the membrane, and this effect seems to be dynamin dependent. Using fragments of full-length WNK1, it also is shown that the effect depends on residues in the middle section of the protein (502 to 1100 WNK1) that contains the acidic motif. Together, these findings emphasize that the molecular mechanisms that underpin WNK1 regulation of ROMK expression are distinct from those that affect NCCT expression.
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Affiliation(s)
- Georgina Cope
- Department of Medicine, University of Cambridge, Cambridge, UK
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63
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Poulsen AN, Klausen TL, Pedersen PS, Willumsen NJ, Frederiksen O. Nucleotide regulation of paracellular Cl- permeability in natural rabbit airway epithelium. Pflugers Arch 2005; 452:188-98. [PMID: 16374638 DOI: 10.1007/s00424-005-0023-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Accepted: 11/07/2005] [Indexed: 10/25/2022]
Abstract
In this study, we demonstrate a novel regulatory mechanism by which mucosal nucleotides via P2Y receptors decrease paracellular Cl(-) ion permeability in natural rabbit airway epithelium (in addition to a decrease in active Na(+) absorption). In contrast to primary cultures, the natural airway epithelium is a low-resistance epithelium, and an equivalent circuit model predicts that changes of more than approximately 12% in transepithelial conductance (G (t)) must include an effect on paracellular conductance (G (s)). Mucosal P2Y receptor stimulation with uridine triphosphate (UTP; 200 microM) decreased G (t) by up to 50% (average, 24%) and simultaneously decreased the paracellular Cl(-) permeability (mucosa-to-serosa Cl(-) flux) by 16%, but had no effect on mannitol permeability. The G (t) response to UTP was mimicked and attenuated by ionomycin (1 microM), suggesting a dependence on Ca(2+) (i). Amiloride (100 microM) and hyperosmolarity (+75 mM mannitol) also decreased G (t), indicating a role of cell shrinkage. Elevation of cAMP with forskolin (8 microM) or isoproterenol (10 microM) increased G (t) by 55 and 32%, and forskolin increased paracellular Cl(-) permeability by 37% without affecting mannitol permeability. The opposite effects of Ca(2+) (i) and cAMP on G (t) suggest an autocrine nucleotide signaling sequence where P2Y-dependent decrease in passive, paracellular Cl(-) transport is succeeded by a reversion of this effect due to P1-receptor-stimulated cAMP formation by adenosine originating from a time-dependent breakdown of mucosal ATP.
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Affiliation(s)
- Asser Nyander Poulsen
- Department of Medical Physiology, The Panum Institute, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
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64
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Leng Q, Kahle KT, Rinehart J, MacGregor GG, Wilson FH, Canessa CM, Lifton RP, Hebert SC. WNK3, a kinase related to genes mutated in hereditary hypertension with hyperkalaemia, regulates the K+ channel ROMK1 (Kir1.1). J Physiol 2005; 571:275-86. [PMID: 16357011 PMCID: PMC1796803 DOI: 10.1113/jphysiol.2005.102202] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The serine-threonine kinase WNK3 modulates Cl- transport into and out of cells through its regulation of SLC12A cation/Cl- cotransporters, implicating it as (one of) the long-sought Cl-/volume-sensitive kinase(s). Integrators in homeostatic systems regulate structurally diverse but functionally coupled elements. For example, the related kinase WNK4 regulates the Na-Cl co-transporter (NCC), paracellular Cl- flux, and the K+ channel ROMK1 (Kir1.1) to maintain renal NaCl and K+ homeostasis; mutations in PRKWNK4, encoding WNK4, cause a Mendelian disease featuring hypertension and hyperkalemia. It is known that WNK3 is expressed in the nephron's distal convoluted tubule (DCT) and stimulates NCC activity. Here, we show that WNK3 is also expressed in cortical and outer medullary collecting duct principal cells. Accordingly, we tested WNK3's effect on the mediators of NaCl and K+ handling in these nephron segments--the epithelial sodium channel (ENaC), paracellular Cl- flux, and ROMK1--using established model systems. WNK3 did not alter paracellular Cl- flux in tetracycline-responsive MDCK II cells, nor affect amiloride-sensitive currents when co-expressed with ENaC in Xenopus laevis oocytes. However, additional co-expression studies in oocytes revealed WNK3 inhibited the renal-specific K+ channel ROMK1 activity greater than 5.5-fold (p < .0001) by altering its plasmalemmal surface expression; WNK3 did not affect ROMK1's conductance or open/closed probability. In contrast, WNK3 had no effect on the activity of the cardiac long-QT syndrome K+ channel KCNQ1/KCNE1 when co-expressed in oocytes. Inhibition of ROMK1 is independent of WNK3's catalytic activity and is mediated by WNK3's carboxyl terminus--a mechanism distinct from its known kinase-dependent activation of NCC. A kinase-inactivating point mutation, or a missense mutation homologous to one in WNK4 that causes disease produced a gain-of-function effect, enhancing WNK3's inhibition of ROMK1 greater than 2.5-fold relative to wild type kinase (p < .0001). The magnitude and specificity of WNK3's effects at both NCC and ROMK1, its co-expression with its targets in the distal nephron, and the established in vivo effect of WNK4 at these same targets provide evidence that WNK3's action is physiologically relevant. WNK3 is likely a component of one of the mechanisms that determines the balance between renal NaCl reabsorption and K+ secretion.
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Affiliation(s)
- Qiang Leng
- Department of Molecular and Cellular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
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65
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Rinehart J, Kahle KT, de Los Heros P, Vazquez N, Meade P, Wilson FH, Hebert SC, Gimenez I, Gamba G, Lifton RP. WNK3 kinase is a positive regulator of NKCC2 and NCC, renal cation-Cl- cotransporters required for normal blood pressure homeostasis. Proc Natl Acad Sci U S A 2005; 102:16777-82. [PMID: 16275913 PMCID: PMC1283841 DOI: 10.1073/pnas.0508303102] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
WNK1 and WNK4 [WNK, with no lysine (K)] are serine-threonine kinases that function as molecular switches, eliciting coordinated effects on diverse ion transport pathways to maintain homeostasis during physiological perturbation. Gain-of-function mutations in either of these genes cause an inherited syndrome featuring hypertension and hyperkalemia due to increased renal NaCl reabsorption and decreased K(+) secretion. Here, we reveal unique biochemical and functional properties of WNK3, a related member of the WNK kinase family. Unlike WNK1 and WNK4, WNK3 is expressed throughout the nephron, predominantly at intercellular junctions. Because WNK4 is a potent inhibitor of members of the cation-cotransporter SLC12A family, we used coexpression studies in Xenopus oocytes to investigate the effect of WNK3 on NCC and NKCC2, related kidney-specific transporters that mediate apical NaCl reabsorption in the thick ascending limb and distal convoluted tubule, respectively. In contrast to WNK4's inhibitory activity, kinase-active WNK3 is a potent activator of both NKCC2 and NCC-mediated transport. Conversely, in its kinase-inactive state, WNK3 is a potent inhibitor of NKCC2 and NCC activity. WNK3 regulates the activity of these transporters by altering their expression at the plasma membrane. Wild-type WNK3 increases and kinase-inactive WNK3 decreases NKCC2 phosphorylation at Thr-184 and Thr-189, sites required for the vasopressin-mediated plasmalemmal translocation and activation of NKCC2 in vivo. The effects of WNK3 on these transporters and their coexpression in renal epithelia implicate WNK3 in NaCl, water, and blood pressure homeostasis, perhaps via signaling downstream of vasopressin.
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Affiliation(s)
- Jesse Rinehart
- Department of Genetics, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
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66
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Kahle KT, Rinehart J, de Los Heros P, Louvi A, Meade P, Vazquez N, Hebert SC, Gamba G, Gimenez I, Lifton RP. WNK3 modulates transport of Cl- in and out of cells: implications for control of cell volume and neuronal excitability. Proc Natl Acad Sci U S A 2005; 102:16783-8. [PMID: 16275911 PMCID: PMC1283843 DOI: 10.1073/pnas.0508307102] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The regulation of Cl(-) transport into and out of cells plays a critical role in the maintenance of intracellular volume and the excitability of GABA responsive neurons. The molecular determinants of these seemingly diverse processes are related ion cotransporters: Cl(-) influx is mediated by the Na-K-2Cl cotransporter NKCC1 and Cl(-) efflux via K-Cl cotransporters, KCC1 or KCC2. A Cl(-)/volume-sensitive kinase has been proposed to coordinately regulate these activities via altered phosphorylation of the transporters; phosphorylation activates NKCC1 while inhibiting KCCs, and dephosphorylation has the opposite effects. We show that WNK3, a member of the WNK family of serine-threonine kinases, colocalizes with NKCC1 and KCC1/2 in diverse Cl(-)-transporting epithelia and in neurons expressing ionotropic GABA(A) receptors in the hippocampus, cerebellum, cerebral cortex, and reticular activating system. By expression studies in Xenopus oocytes, we show that kinase-active WNK3 increases Cl(-) influx via NKCC1, and that it inhibits Cl(-) exit through KCC1 and KCC2; kinase-inactive WNK3 has the opposite effects. WNK3's effects are imparted via altered phosphorylation and surface expression of its downstream targets and bypass the normal requirement of altered tonicity for activation of these transporters. Together, these data indicate that WNK3 can modulate the level of intracellular Cl(-) via opposing actions on entry and exit pathways. They suggest that WNK3 is part of the Cl(-)/volume-sensing mechanism necessary for the maintenance of cell volume during osmotic stress and the dynamic modulation of GABA neurotransmission.
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Affiliation(s)
- Kristopher T Kahle
- Department of Genetics, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
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67
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Hadchouel J, Delaloy C, Fauré S, Achard JM, Jeunemaitre X. Familial Hyperkalemic Hypertension. J Am Soc Nephrol 2005; 17:208-17. [PMID: 16221868 DOI: 10.1681/asn.2005030314] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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68
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Yamauchi K, Yang SS, Ohta A, Sohara E, Rai T, Sasaki S, Uchida S. Apical localization of renal K channel was not altered in mutant WNK4 transgenic mice. Biochem Biophys Res Commun 2005; 332:750-5. [PMID: 15907795 DOI: 10.1016/j.bbrc.2005.04.169] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Accepted: 04/30/2005] [Indexed: 11/17/2022]
Abstract
Missense mutations in the WNK4 gene have been postulated to cause pseudohypoaldosteronism type II, an autosomal-dominant disorder characterized by hyperkalemia and hypertension. A previous study using Xenopus oocytes showed that wild-type WNK4 expression inhibited surface expression of renal K channel (ROMK) and that a disease-causing mutant further decreased the surface expression. The decreased surface expression of ROMK caused by mutant WNK4 was postulated to be a mechanism for decreased potassium secretion in distal nephrons that would presumably lead to hyperkalemia. To determine if the mutant WNK4 had such an inhibitory effect on the apical localization of ROMK in vivo, we generated transgenic mice using the CLCNKB gene promoter that expressed a mutant WNK4 (D564A) in distal nephrons. In contrast to the tight junction localization of wild-type WNK4 described previously, the mutant WNK4 was present in the cytoplasm in the distal tubules and in the apical membranes in the thick ascending limb of Henle's loop. In both cell types, the apical localization of endogenous ROMK was not influenced by the co-expression of mutant WNK4. This result indicates that the mutant WNK4 does not have a dominant effect on the cellular localization of ROMK in vivo.
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Affiliation(s)
- Kozue Yamauchi
- Department of Nephrology, Graduate School of Medicine, Tokyo Medical and Dental University, Japan
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69
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Newhouse SJ, Wallace C, Dobson R, Mein C, Pembroke J, Farrall M, Clayton D, Brown M, Samani N, Dominiczak A, Connell JM, Webster J, Lathrop GM, Caulfield M, Munroe PB. Haplotypes of the WNK1 gene associate with blood pressure variation in a severely hypertensive population from the British Genetics of Hypertension study. Hum Mol Genet 2005; 14:1805-14. [PMID: 15888480 DOI: 10.1093/hmg/ddi187] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in the WNK1 gene cause Gordon's syndrome, a rare Mendelian form of hypertension. We assessed whether common WNK1 variants might also contribute to essential hypertension (EH), a multifactorial disorder affecting > 25% of the adult population worldwide. A panel of 19 single nucleotide polymorphisms (SNPs) spanning the gene was selected from public databases and was genotyped in 100 white European families to determine the pattern of linkage disequilibrium, haplotype structure and tagging SNPs for the WNK1 locus. Eight tagging SNPs were identified with 90% power to predict common WNK1 haplotypes and SNPs. Family-based association tests were used to test for association with EH and severity of hypertension in 712 severely hypertensive families from the MRC British Genetics of Hypertension study resource. No association was found between WNK1 polymorphisms or haplotypes with hypertension; however, one SNP rs1468326, located 3 kb from the WNK1 promoter, was found to be nominally associated with severity of hypertension, with both systolic blood pressure (BP) (Z = +2.24, P = 0.025) and diastolic BP (Z = +1.99, P = 0.046). We also found nominal support for association of one common WNK1 haplotype with increased systolic BP (Z = +1.91, P = 0.053). This is the first study to perform haplotype association analysis of the WNK1 gene with EH. This finding of association between a SNP near the promoter region and the severity of hypertension suggests that increased expression of WNK1 might contribute to BP variability and susceptibility to EH similar to the mechanism of hypertension observed in Gordon's syndrome.
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Affiliation(s)
- Stephen J Newhouse
- Clinical Pharmacology and Barts and The London Genome Centre, William Harvey Research Institute, Barts and the London School of Medicine, London, UK
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70
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Lenertz LY, Lee BH, Min X, Xu BE, Wedin K, Earnest S, Goldsmith EJ, Cobb MH. Properties of WNK1 and implications for other family members. J Biol Chem 2005; 280:26653-8. [PMID: 15883153 DOI: 10.1074/jbc.m502598200] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
WNKs are large serine/threonine protein kinases structurally distinct from all other members of the protein kinase superfamily. Of the four human WNK family members, WNK1 and WNK4 have been linked to a hereditary form of hypertension, pseudohypoaldosteronism type II. We characterized the biochemical properties and regulation of WNK1 that may contribute to its physiological activities and abnormal function in disease. We showed that WNK1 is activated by hypertonic stress in kidney epithelial cells and in breast and colon cancer cell lines. In addition, hypotonic stress also led to a modest increase in WNK1 activity. Gel filtration suggested that WNK1 exists as a tetramer, and yeast two-hybrid data showed that the N terminus of WNK1 (residues 1-222) interacts with residues 481-660, which includes the WNK1 autoinhibitory domain and a C-terminal coiled-coil domain. Although cell biological studies have suggested a functional interaction between WNK1 and WNK4, we found no evidence of stable interactions between these kinases. However, WNK1 phosphorylated both WNK4 and WNK2. In addition, the WNK1 autoinhibitory domain inhibited the catalytic activity of these WNKs. These findings suggest potential mechanisms for interconnected regulation of WNK family members.
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Affiliation(s)
- Lisa Y Lenertz
- Department of Pharmacology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA
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71
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Yang CL, Zhu X, Wang Z, Subramanya AR, Ellison DH. Mechanisms of WNK1 and WNK4 interaction in the regulation of thiazide-sensitive NaCl cotransport. J Clin Invest 2005; 115:1379-87. [PMID: 15841204 PMCID: PMC1074678 DOI: 10.1172/jci22452] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2004] [Accepted: 02/15/2005] [Indexed: 11/17/2022] Open
Abstract
With-no-lysine (WNK) kinases are highly expressed along the mammalian distal nephron. Mutations in either WNK1 or WNK4 cause familial hyperkalemic hypertension (FHHt), suggesting that the protein products converge on a final common pathway. We showed previously that WNK4 downregulates thiazide-sensitive NaCl cotransporter (NCC) activity, an effect suppressed by WNK1. Here we investigated the mechanisms by which WNK1 and WNK4 interact to regulate ion transport. We report that WNK1 suppresses the WNK4 effect on NCC activity and associates with WNK4 in a protein complex involving the kinase domains. Although a kinase-dead WNK1 also associates with WNK4, it fails to suppress WNK4-mediated NCC inhibition; the WNK1 kinase domain alone, however, is not sufficient to block the WNK4 effect. The carboxyterminal 222 amino acids of WNK4 are sufficient to inhibit NCC, but this fragment is not blocked by WNK1. Instead, WNK1 inhibition requires an intact WNK4 kinase domain, the region that binds to WNK1. In summary, these data show that: (a) the WNK4 carboxyl terminus mediates NCC suppression, (b) the WNK1 kinase domain interacts with the WNK4 kinase domain, and (c) WNK1 inhibition of WNK4 is dependent on WNK1 catalytic activity and an intact WNK1 protein. These findings provide insight into the complex interrelationships between WNK1 and WNK4 and provide a molecular basis for FHHt.
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Affiliation(s)
- Chao-Ling Yang
- Division of Nephrology and Hypertension, Oregon Health & Science University, Portland, 97239, USA
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72
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Gamba G. Molecular Physiology and Pathophysiology of Electroneutral Cation-Chloride Cotransporters. Physiol Rev 2005; 85:423-93. [PMID: 15788703 DOI: 10.1152/physrev.00011.2004] [Citation(s) in RCA: 572] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Electroneutral cation-Cl−cotransporters compose a family of solute carriers in which cation (Na+or K+) movement through the plasma membrane is always accompanied by Cl−in a 1:1 stoichiometry. Seven well-characterized members include one gene encoding the thiazide-sensitive Na+−Cl−cotransporter, two genes encoding loop diuretic-sensitive Na+−K+−2Cl−cotransporters, and four genes encoding K+−Cl−cotransporters. These membrane proteins are involved in several physiological activities including transepithelial ion absorption and secretion, cell volume regulation, and setting intracellular Cl−concentration below or above its electrochemical potential equilibrium. In addition, members of this family play an important role in cardiovascular and neuronal pharmacology and pathophysiology. Some of these cotransporters serve as targets for loop diuretics and thiazide-type diuretics, which are among the most commonly prescribed drugs in the world, and inactivating mutations of three members of the family cause inherited diseases such as Bartter's, Gitelman's, and Anderman's diseases. Major advances have been made in the past decade as consequences of molecular identification of all members in this family. This work is a comprehensive review of the knowledge that has evolved in this area and includes molecular biology of each gene, functional properties of identified cotransporters, structure-function relationships, and physiological and pathophysiological roles of each cotransporter.
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Affiliation(s)
- Gerardo Gamba
- Molecular Physiology Unit, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Universidad Nacional Autónoma de México, Mexico City, Mexico.
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73
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Kahle KT, Wilson FH, Lifton RP. Regulation of diverse ion transport pathways by WNK4 kinase: a novel molecular switch. Trends Endocrinol Metab 2005; 16:98-103. [PMID: 15808806 DOI: 10.1016/j.tem.2005.02.012] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Key components of complex physiological regulatory pathways can be uncovered through the molecular-genetic study of rare, inherited diseases. WNK kinases are a recently discovered class of serine-threonine kinases that are distinctive because of the substitution of cysteine for lysine in subdomain II of the catalytic domain. Mutations in PRKWNK1 and PRKWNK4, which encode WNK1 and WNK4, result in an inherited syndrome of hypertension and hyperkalemia. Recent physiological work has revealed that WNK4 alters the balance of NaCl reabsorption and K(+) secretion in the distal nephron by actions on both transcellular and paracellular ion-flux pathways. Additionally, WNK4 is expressed in extra-renal epithelia with prominent roles in Cl(-) handling, and it regulates transporters that are responsible for Cl(-) flux across apical and basolateral membranes. WNK kinases are components of a novel signaling pathway that is important for the control of blood pressure and electrolyte homeostasis.
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Affiliation(s)
- Kristopher T Kahle
- Departments of Genetics, Medicine, Molecular Biophysics and Biochemistry and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
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74
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Gamba G. Role of WNK kinases in regulating tubular salt and potassium transport and in the development of hypertension. Am J Physiol Renal Physiol 2005; 288:F245-52. [PMID: 15637347 DOI: 10.1152/ajprenal.00311.2004] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A recently discovered family of protein kinases is responsible for an autosomal-dominant disease known as Gordon's syndrome or pseudohypoaldosteronism type II (PHA-II) that features hyperkalemia and hyperchloremic metabolic acidosis, accompanied by hypertension and hypercalciuria. Four genes have been described in this kinase family, which has been named WNK, due to the absence of a key lysine in kinase subdomain II (with no K kinases). Two of these genes, WNK1 and WNK4 located in human chromosomes 12 and 17, respectively, are responsible for PHA-II. Immunohystochemical analysis revealed that WNK1 and WNK4 are predominantly expressed in the distal convoluted tubule and collecting duct. The physiological studies have shown that WNK4 downregulates the activity of ion transport pathways expressed in these nephron segments, such as the apical thiazide-sensitive Na+-Cl−cotransporter and apical secretory K+channel ROMK, as well as upregulates paracellular chloride transport and phosphorylation of tight junction proteins such as claudins. In addition, WNK4 downregulates other Cl−influx pathways such as the basolateral Na+-K+-2Cl−cotransporter and Cl−/HCO3−exchanger. WNK4 mutations behave as a loss of function for the Na+-Cl−cotransporter and a gain of function when it comes to ROMK and claudins. These dual effects of WNK4 mutations fit with proposed mechanisms for developing electrolyte abnormalities and hypertension in PHA-II and point to WNK4 as a multifunctional regulator of diverse ion transporters.
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Affiliation(s)
- Gerardo Gamba
- Molecular Physiology Unit, Instituto de Ciencias Médicas y Nutrición Salvador Zubirán, Vasco de Quiroga No. 15, Tlalpan 14000, México City, Mexico.
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75
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Hadchouel J, Delaloy C, Jeunemaitre X. WNK1 et WNK4, nouveaux acteurs de l’homéostasie hydrosodée. Med Sci (Paris) 2005; 21:55-60. [PMID: 15639021 DOI: 10.1051/medsci/200521155] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Arterial hypertension is a complex trait influenced by a variety of environmental and genetic factors. Several approaches can be used to identify its susceptibility genes : one is to study rare monogenic forms of hypertension, like familial hyperkalemic hypertension (FHH). Also known as pseudohypoaldosteronism type 2 or Gordon syndrome, FHH is characterized by hypertension, hyperkalemia despite normal renal glomerular filtration rate, abnormalities which are particularly sensitive to thiazide diuretics. Mild hyperchloremia, metabolic acidosis, and suppressed plasma renin activity are associated findings. Despite its phenotypic and genetic heterogeneity, mutations in two related genes, WNK1 and WNK4, were recently identified. These genes belong to a newly identified family of serine-threonine (with no lysine [K]) kinases. Both are highly expressed in the kidney and in a variety of epithelia involved in chloride transport. It has thus been postulated that these two kinases could be implicated in a new pathway of ionic transport regulation. Several studies have very recently confirmed this hypothesis in vitro, in Xenopus oocytes or kidney cell lines. They have shown that, in the renal distal tubule, WNK4 inhibits sodium reabsorption and potassium secretion, via inhibition of NCC (thiazide-sensitive Na+-Cl- cotransporter) and K+ channel ROMK activity, respectively. Interestingly, FHH mutations have opposite effects : while they lead to loss of NCC inhibition, they increase ROMK inhibition. Moreover, they also increase paracellular permeability to chloride of MDCK cells. WNK4 also inhibits apical and basal chloride transporters present in extra-renal epithelia, such as CFEX and Na+-K+-2 Cl-, respectively. It is also interesting to note that the WNK4-mediated negative regulation of NCC activity is in turn inhibited by WNK1. By its role on several transporters, WNK4 appears as a putative key regulator of ionic transport and blood pressure.
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Affiliation(s)
- Juliette Hadchouel
- Inserm U.36, Collège de France, 11, place Marcelin Berthelot, 75005 Paris, France
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76
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Zeng G, Gao L, Xia T, Gu Y, Yu RK. Expression of the mouse WNK1 gene in correlation with ganglioside GD3 and functional analysis of the mouse WNK1 promoter. Gene 2005; 344:233-9. [PMID: 15656989 DOI: 10.1016/j.gene.2004.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Revised: 09/17/2004] [Accepted: 10/05/2004] [Indexed: 10/26/2022]
Abstract
WNK1 is one of WNK (With No K=Lysine) protein kinases which comprise a newly described subfamily. Our studies showed that expression of the mouse WNK1 gene was dramatically suppressed in a tumor cell line when its phenotype was altered by suppression of the GD3-synthase gene expression. The mouse WNK1 gene was expressed at a high level at early stage of embryonic brain and its expression decreased as brain developed, similar to the expression pattern of the GD3-synthase gene. To study transcriptional regulation, we cloned a 5'-flanking 1239-bp fragment of the mouse WNK1 gene. This fragment contains a number of potential consensus binding sites for transcription factors, including Sp1, AP2, CCAAT, Est-1, Oct-1, CNBP, and NFkB, but lacks a TATA box. Primer extension identified multiple putative transcriptional initiation sites, including several sites downstream of the ATG codon. Activities of the promoter fragments were assessed in mouse breast Sa/R-MT cells by transient transfection and the results showed that the promoter elements between -700 and -977 is required for maintaining a high level of promoter activity of the TATA-less mouse WNK1 gene.
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Affiliation(s)
- Guichao Zeng
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, 1120 15th Street CB-2803, Augusta, GA 30912, USA.
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77
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Náray-Fejes-Tóth A, Snyder PM, Fejes-Tóth G. The kidney-specific WNK1 isoform is induced by aldosterone and stimulates epithelial sodium channel-mediated Na+ transport. Proc Natl Acad Sci U S A 2004; 101:17434-9. [PMID: 15583131 PMCID: PMC536044 DOI: 10.1073/pnas.0408146101] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
WNK1 belongs to a unique family of Ser/Thr kinases that have been implicated in the control of blood pressure. Intronic deletions in the WNK1 gene result in its overexpression and lead to pseudohypoaldosteronism type II, a disease with salt-sensitive hypertension and hyperkalemia. How overexpression of WNK1 leads to Na(+) retention and hypertension is not entirely clear. Similarly, there is no information on the hormonal regulation of expression of WNK kinases. There are two main WNK1 transcripts expressed in the kidney: the originally described "long" WNK1 and a shorter transcript that is specifically expressed in the kidney (KS-WNK1). The goal of this study was to determine the effect of aldosterone, the main hormonal regulator of Na(+) homeostasis, on the transcription of WNK1 isoforms in renal target cells, by using an unique mouse cortical collecting duct cell line that stably expresses functional mineralocorticoid receptors. Our results demonstrate that aldosterone, at physiological concentrations, rapidly induces the expression of the KS-WNK1 but not that of the long-WNK1 in these cells. Importantly, stable overexpression of KS-WNK1 significantly increases transepithelial Na(+) transport in cortical collecting duct cells. Similarly, coexpression of KS-WNK1 and the epithelial Na(+) channel in Fischer rat thyroid epithelial cells also stimulates Na(+) current, suggesting that KS-WNK1 affects the subcellular location or activity but not the expression of epithelial Na(+) channel. These observations suggest that stimulation of KS-WNK1 expression might be an important element of aldosterone-induced Na(+) retention and hypertension.
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78
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Quentin F, Chambrey R, Trinh-Trang-Tan MM, Fysekidis M, Cambillau M, Paillard M, Aronson PS, Eladari D. The Cl−/HCO3−exchanger pendrin in the rat kidney is regulated in response to chronic alterations in chloride balance. Am J Physiol Renal Physiol 2004; 287:F1179-88. [PMID: 15292050 DOI: 10.1152/ajprenal.00211.2004] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pendrin (Pds; Slc26A4) is a new anion exchanger that is believed to mediate apical Cl−/HCO3−exchange in type B and non-A-non-B intercalated cells of the connecting tubule and cortical collecting duct. Recently, it has been proposed that this transporter may be involved in NaCl balance and blood pressure regulation in addition to its participation in the regulation of acid-base status. The purpose of our study was to determine the regulation of Pds protein abundance during chronic changes in chloride balance. Rats were subjected to either NaCl, NH4Cl, NaHCO3, KCl, or KHCO3loading for 6 days or to a low-NaCl diet or chronic furosemide administration. Pds protein abundance was estimated by semiquantitative immunoblotting in renal membrane fractions isolated from the cortex of treated and control rats. We observed a consistent inverse relationship between Pds expression and diet-induced changes in chloride excretion independent of the administered cation. Conversely, NaCl depletion induced by furosemide was associated with increased Pds expression. We conclude that Pds expression is specifically regulated in response to changes in chloride balance.
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Affiliation(s)
- Fabienne Quentin
- Institut National de la Santé et de la Recherche Médicale Unité 356, Institut Fédératif de Recherche 58, Université René Descartes, Paris, France
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79
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Jensen P, Magdaleno S, Lehman KM, Rice DS, Lavallie ER, Collins-Racie L, McCoy JM, Curran T. A neurogenomics approach to gene expression analysis in the developing brain. ACTA ACUST UNITED AC 2004; 132:116-27. [PMID: 15582152 DOI: 10.1016/j.molbrainres.2004.10.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/05/2004] [Indexed: 11/20/2022]
Abstract
Secreted and transmembrane proteins provide critical functions in the signaling networks essential for neurogenesis. We used a genetic signal sequence gene trap approach to isolate 189 genes expressed during development in e16.5 whole head, e16.5 hippocampus and e14.5 cerebellum. Gene ontology programs were used to classify the genes into respective biological processes. Four major classes of biological processes known to be important during development were identified: cell communication, cell physiology processes, metabolism and morphogenesis. We used in situ hybridization to determine the temporal and spatial patterns of gene expression in the developing brain using this set of probes. The results demonstrate that gene expression patterns can highlight potential gene functions in specific brain regions. We propose that combining bioinformatics with the gene expression pattern is an effective strategy to identify genes that may play critical roles during brain development.
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Affiliation(s)
- Patricia Jensen
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, United States
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80
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Kahle KT, Macgregor GG, Wilson FH, Van Hoek AN, Brown D, Ardito T, Kashgarian M, Giebisch G, Hebert SC, Boulpaep EL, Lifton RP. Paracellular Cl- permeability is regulated by WNK4 kinase: insight into normal physiology and hypertension. Proc Natl Acad Sci U S A 2004; 101:14877-82. [PMID: 15465913 PMCID: PMC522037 DOI: 10.1073/pnas.0406172101] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Paracellular ion flux across epithelia occurs through selective and regulated pores in tight junctions; this process is poorly understood. Mutations in the kinase WNK4 cause pseudohypoaldosteronism type II (PHAII), a disease featuring hypertension and hyperkalemia. Whereas WNK4 is known to regulate several transcellular transporters and channels involved in NaCl and K+ homeostasis, its localization to tight junctions suggests it might also regulate paracellular flux. We performed electrophysiology on mammalian kidney epithelia with inducible expression of various WNK4 constructs. Induction of wild-type WNK4 reduced transepithelial resistance by increasing absolute chloride permeability. PHAII-mutant WNK4 produced markedly larger effects, whereas kinase-mutant WNK4 had no effect. The electrochemical and pharmacologic properties of these effects indicate they are attributable to the paracellular pathway. The effects of WNK4 persist when induction is delayed until after tight-junction formation, demonstrating a dynamic effect. WNK4 did not alter the flux of uncharged solutes, or the expression or localization of selected tight-junction proteins. Transmission and freeze-fracture electron microscopy showed no effect of WNK4 on tight-junction structure. These findings implicate WNK signaling in the coordination of transcellular and paracellular flux to achieve NaCl and K+ homeostasis, explain PHAII pathophysiology, and suggest that modifiers of WNK signaling may be potent antihypertensive agents.
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Affiliation(s)
- Kristopher T Kahle
- Department of Genetics, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
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81
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Lee BH, Min X, Heise CJ, Xu BE, Chen S, Shu H, Luby-Phelps K, Goldsmith EJ, Cobb MH. WNK1 Phosphorylates Synaptotagmin 2 and Modulates Its Membrane Binding. Mol Cell 2004; 15:741-51. [PMID: 15350218 DOI: 10.1016/j.molcel.2004.07.018] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2003] [Revised: 06/14/2004] [Accepted: 06/17/2004] [Indexed: 11/16/2022]
Abstract
WNK (with no lysine [K]) protein kinases were named for their unique active site organization. Mutations in WNK1 and WNK4 cause a familial form of hypertension by undefined mechanisms. Here, we report that WNK1 selectively binds to and phosphorylates synaptotagmin 2 (Syt2) within its calcium binding C2 domains. Endogenous WNK1 and Syt2 coimmunoprecipitate and colocalize on a subset of secretory granules in INS-1 cells. Phosphorylation by WNK1 increases the amount of Ca2+ required for Syt2 binding to phospholipid vesicles; mutation of threonine 202, a WNK1 phosphorylation site, partially prevents this change. These findings suggest that phosphorylation of Syts by WNK1 can regulate Ca2+ sensing and the subsequent Ca2+-dependent interactions mediated by Syt C2 domains. These findings provide a biochemical mechanism that could lead to the retention or insertion of proteins in the plasma membrane. Interruption of this regulatory pathway may disturb membrane events that regulate ion balance.
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Affiliation(s)
- Byung-Hoon Lee
- Department of Pharmacology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
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82
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Kahle KT, Wilson FH, Lalioti M, Toka H, Qin H, Lifton RP. WNK kinases: molecular regulators of integrated epithelial ion transport. Curr Opin Nephrol Hypertens 2004; 13:557-62. [PMID: 15300163 DOI: 10.1097/00041552-200409000-00012] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW The WNK kinases are a recently discovered family of serine-threonine kinases that have been shown to play an essential role in the regulation of electrolyte homeostasis. This review focuses on the recent evidence elucidating the functions of these kinases in normal and disease physiology. RECENT FINDINGS Mutations in WNK1 and WNK4 have been shown to cause pseudohypoaldosteronism type II, a disease featuring hypertension with hyperkalemia. Recent work has demonstrated that WNK4 is a potent inhibitor of diverse epithelial transporters including the thiazide-sensitive sodium chloride co-transporter (NCCT) and the renal outer medullary potassium ion channel. In addition, WNK4 activity promotes paracellular chloride ion flux. Importantly, mutations in WNK4 that cause disease have divergent effects on these transport pathways. WNK4 mutations relieve the inhibition of NCCT, increase the inhibition of the renal outer medullary potassium ion channel, and further increase paracellular chloride ion flux. These findings can explain the observed physiological abnormalities in patients with pseudohypoaldosteronism type II, and support a model in which WNK4 is a molecular switch that can alter the balance between chloride ion reabsorption and potassium ion secretion. The WNK kinases are also found in diverse epithelia throughout the body that are involved in chloride ion flux, suggesting that these kinases may play a general role in the regulation of chloride ion flux. SUMMARY The WNK kinases define a previously unrecognized signaling pathway that is essential for the integrated regulation of electrolyte homeostasis. Their function has implications for understanding the coordinated regulation of electrolyte homeostasis and blood pressure, and identifies WNKs as dynamic regulators of the paracellular flux pathway.
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Affiliation(s)
- Kristopher T Kahle
- Department of Genetics and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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83
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Holden S, Cox J, Raymond FL. Cloning, genomic organization, alternative splicing and expression analysis of the human gene WNK3 (PRKWNK3). Gene 2004; 335:109-19. [PMID: 15194194 DOI: 10.1016/j.gene.2004.03.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2003] [Revised: 03/04/2004] [Accepted: 03/09/2004] [Indexed: 11/28/2022]
Abstract
We report the isolation of a full length coding WNK3 cDNA from human fetal brain. The WNK3 transcript has an open reading frame of 5403 nucleotides and encodes a putative protein of 1800 amino acids. The human WNK3 gene comprises 24 exons and lies within a 559 kb genomic segment on chromosome Xp11.22 which has conserved synteny with a 705 kb genomic segment of human chromosome 9q22.31 which contains WNK2. The WNK3 transcript is expressed in several human fetal and adult tissues and has at least two splice isoforms generated by the alternative splicing of exon 18 and exon 22 which maintain the open reading frame. Usage of exon 18b is restricted to brain and introduces an additional 47 amino acids into the predicted protein. The predicted WNK3 protein has a similar structural organization to the other human WNK kinases. Significant homology between these proteins is confined to three conserved regions of their amino acid sequences which we have designated CR1, CR2 and CR3. CR1 and CR3 contain highly conserved residues which have been shown to be important for the normal function of WNK1 and WNK4, and CR2 contains a highly conserved 22 amino acid motif specific to chordate species. WNK3 lies within the critical linkage interval for several human monogenic disorders, including X-linked mental retardation. The function of mammalian WNK3 kinase remains to be investigated.
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Affiliation(s)
- Simon Holden
- Department of Medical Genetics, Cambridge Institute for Medical Research, Addenbrooke's Hospital Box 139, Hills Road, Cambridge, CB2 2XY, UK
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84
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Kokubo Y, Kamide K, Inamoto N, Tanaka C, Banno M, Takiuchi S, Kawano Y, Tomoike H, Miyata T. Identification of 108 SNPs in TSC, WNK1, and WNK4 and their association with hypertension in a Japanese general population. J Hum Genet 2004; 49:507-515. [PMID: 15309683 DOI: 10.1007/s10038-004-0181-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2004] [Accepted: 06/22/2004] [Indexed: 10/26/2022]
Abstract
The deletion of thiazide-sensitive Na-Cl cotransporter ( TSC, SLC12A3) causes Gitelman's syndrome characterized by low blood pressure, while deletions of the WNK1 ( PRKWNK1) and WNK4 ( PRKWNK4) genes cause familial hypertension known as pseudohypoaldosteronism type II. Recent studies have revealed that cell surface expression of TSC is regulated by WNK1 and WNK4. We hypothesized that molecular variations in TSC, WNK1, and WNK4 could lead to an increased morbidity of hypertension. We identified 52, 35, and 21 polymorphisms in Japanese hypertensives by sequencing the entire coding regions of TSC, WNK1 and WNK4, respectively. Twenty-one representative polymorphisms were genotyped in 1,818 Japanese individuals (771 subjects with hypertension and 1,047 controls) randomly sampled in Suita city. The results indicated that the systolic blood pressure in men with the CT+TT genotype in WNK4 C14717T was 3.1 mmHg higher than those with the CC genotype ( p=0.042) after adjustment with confounding factors such as age, BMI, hyperlipidemia, diabetes mellitus, antihypertensive drug use, smoking, and drinking. Multivariate logistic regression analysis (with adjustment for the same parameters) in men revealed that the odds ratio for the presence of hypertension of the CT+TT genotype in C14717T to the CC genotype was 1.62 ( p=0.010, 95% confidence interval, 1.12-2.33). Association of TSC and WNK1 with hypertension was not observed. In conclusion, our study suggests the possible involvement of WNK4 in essential hypertension in a Japanese general population.
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Affiliation(s)
- Yoshihiro Kokubo
- Division of Preventive Cardiology, National Cardiovascular Center, 5-7-1 Fujishirodai, Suita 565-8565, Japan.
| | - Kei Kamide
- Division of Hypertension and Nephrology, National Cardiovascular Center, Suita, Japan
| | - Nozomu Inamoto
- Division of Preventive Cardiology, National Cardiovascular Center, 5-7-1 Fujishirodai, Suita 565-8565, Japan
| | - Chihiro Tanaka
- Department of Etiology and Pathogenesis, National Cardiovascular Center Research Institute, Suita, Japan
| | - Mariko Banno
- Department of Etiology and Pathogenesis, National Cardiovascular Center Research Institute, Suita, Japan
| | - Shin Takiuchi
- Division of Hypertension and Nephrology, National Cardiovascular Center, Suita, Japan
| | - Yuhei Kawano
- Division of Hypertension and Nephrology, National Cardiovascular Center, Suita, Japan
| | - Hitonobu Tomoike
- Division of Preventive Cardiology, National Cardiovascular Center, 5-7-1 Fujishirodai, Suita 565-8565, Japan
| | - Toshiyuki Miyata
- Department of Etiology and Pathogenesis, National Cardiovascular Center Research Institute, Suita, Japan
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Abstract
The kidney plays a central role in our ability to maintain appropriate sodium balance, which is critical to determination of blood pressure. In this review we outline current knowledge of renal salt handling at the molecular level, and, given that Westernized societies consume more salt than is required for normal physiology, we examine evidence that the lowering of salt intake can combat hypertension.
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86
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Lafrenière RG, MacDonald MLE, Dubé MP, MacFarlane J, O’Driscoll M, Brais B, Meilleur S, Brinkman RR, Dadivas O, Pape T, Platon C, Radomski C, Risler J, Thompson J, Guerra-Escobio AM, Davar G, Breakefield XO, Pimstone SN, Green R, Pryse-Phillips W, Goldberg YP, Younghusband HB, Hayden MR, Sherrington R, Rouleau GA, Samuels ME. Identification of a novel gene (HSN2) causing hereditary sensory and autonomic neuropathy type II through the Study of Canadian Genetic Isolates. Am J Hum Genet 2004; 74:1064-73. [PMID: 15060842 PMCID: PMC1181970 DOI: 10.1086/420795] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2003] [Accepted: 02/25/2004] [Indexed: 11/03/2022] Open
Abstract
Hereditary sensory and autonomic neuropathy (HSAN) type II is an autosomal recessive disorder characterized by impairment of pain, temperature, and touch sensation owing to reduction or absence of peripheral sensory neurons. We identified two large pedigrees segregating the disorder in an isolated population living in Newfoundland and performed a 5-cM genome scan. Linkage analysis identified a locus mapping to 12p13.33 with a maximum LOD score of 8.4. Haplotype sharing defined a candidate interval of 1.06 Mb containing all or part of seven annotated genes, sequencing of which failed to detect causative mutations. Comparative genomics revealed a conserved ORF corresponding to a novel gene in which we found three different truncating mutations among five families including patients from rural Quebec and Nova Scotia. This gene, termed "HSN2," consists of a single exon located within intron 8 of the PRKWNK1 gene and is transcribed from the same strand. The HSN2 protein may play a role in the development and/or maintenance of peripheral sensory neurons or their supporting Schwann cells.
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Affiliation(s)
- Ronald G. Lafrenière
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Marcia L. E. MacDonald
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Marie-Pierre Dubé
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Julie MacFarlane
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Mary O’Driscoll
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Bernard Brais
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Sébastien Meilleur
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Ryan R. Brinkman
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Owen Dadivas
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Terry Pape
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Christèle Platon
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Chris Radomski
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Jenni Risler
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Jay Thompson
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Ana-Maria Guerra-Escobio
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Gudarz Davar
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Xandra O. Breakefield
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Simon N. Pimstone
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Roger Green
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - William Pryse-Phillips
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Y. Paul Goldberg
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - H. Banfield Younghusband
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Michael R. Hayden
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Robin Sherrington
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Guy A. Rouleau
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
| | - Mark E. Samuels
- Xenon Genetics Research, Département de Médecine de l’Université de Montréal et Centre de Recherche du Centre Hospitalier de l’Université de Montréal, and Centre for Research in Neuroscience, McGill University, Montreal; Xenon Genetics, Burnaby, British Columbia; Discipline of Genetics and Faculty of Medicine, Memorial University, St. John’s, Newfoundland; Departments of Neurology and Anesthesiology, Brigham and Women’s Hospital, and Departments of Neurology and Radiology, Massachusetts General Hospital and Neuroscience Program, Harvard Medical School, Boston; and Department of Medical Genetics, University of British Columbia, and Center for Molecular Medicine and Therapeutics, Children and Women’s Hospital, Vancouver
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87
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Vitari AC, Deak M, Collins BJ, Morrice N, Prescott AR, Phelan A, Humphreys S, Alessi DR. WNK1, the kinase mutated in an inherited high-blood-pressure syndrome, is a novel PKB (protein kinase B)/Akt substrate. Biochem J 2004; 378:257-68. [PMID: 14611643 PMCID: PMC1223938 DOI: 10.1042/bj20031692] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2003] [Accepted: 11/11/2003] [Indexed: 01/13/2023]
Abstract
Recent evidence indicates that mutations in the gene encoding the WNK1 [with no K (lysine) protein kinase-1] results in an inherited hypertension syndrome called pseudohypoaldosteronism type II. The mechanisms by which WNK1 is regulated or the substrates it phosphorylates are currently unknown. We noticed that Thr-60 of WNK1, which lies N-terminal to the catalytic domain, is located within a PKB (protein kinase B) phosphorylation consensus sequence. We found that PKB phosphorylated WNK1 efficiently compared with known substrates, and both peptide map and mutational analysis revealed that the major PKB site of phosphorylation was Thr-60. Employing a phosphospecific Thr-60 WNK1 antibody, we demonstrated that IGF1 (insulin-like growth factor) stimulation of HEK-293 cells induced phosphorylation of endogenously expressed WNK1 at Thr-60. Consistent with PKB mediating this phosphorylation, inhibitors of PI 3-kinase (phosphoinositide 3-kinase; wortmannin and LY294002) but not inhibitors of mammalian target of rapamycin (rapamycin) or MEK1 (mitogen-activated protein kinase kinase-1) activation (PD184352), inhibited IGF1-induced phosphorylation of endogenous WNK1 at Thr-60. Moreover, IGF1-induced phosphorylation of endogenous WNK1 did not occur in PDK1-/- ES (embryonic stem) cells, in which PKB is not activated. In contrast, IGF1 still induced normal phosphorylation of WNK1 in PDK1(L155E/L155E) knock-in ES cells in which PKB, but not S6K (p70 ribosomal S6 kinase) or SGK1 (serum- and glucocorticoid-induced protein kinase 1), is activated. Our study provides strong pharmacological and genetic evidence that PKB mediates the phosphorylation of WNK1 at Thr-60 in vivo. We also performed experiments which suggest that the phosphorylation of WNK1 by PKB is not regulating its kinase activity or cellular localization directly. These results provide the first connection between the PI 3-kinase/PKB pathway and WNK1, suggesting a mechanism by which this pathway may influence blood pressure.
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Affiliation(s)
- Alberto C Vitari
- MRC Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB complex, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, UK.
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89
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Kahle KT, Gimenez I, Hassan H, Wilson FH, Wong RD, Forbush B, Aronson PS, Lifton RP. WNK4 regulates apical and basolateral Cl- flux in extrarenal epithelia. Proc Natl Acad Sci U S A 2004; 101:2064-9. [PMID: 14769928 PMCID: PMC357052 DOI: 10.1073/pnas.0308434100] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Mutations in the serine-threonine kinase WNK4 [with no lysine (K) 4] cause pseudohypoaldosteronism type II, a Mendelian disease featuring hypertension with hyperkalemia. In the kidney, WNK4 regulates the balance between NaCl reabsorption and K(+) secretion via variable inhibition of the thiazide-sensistive NaCl cotransporter and the K(+) channel ROMK. We now demonstrate expression of WNK4 mRNA and protein outside the kidney. In extrarenal tissues, WNK4 is found almost exclusively in polarized epithelia, variably associating with tight junctions, lateral membranes, and cytoplasm. Epithelia expressing WNK4 include sweat ducts, colonic crypts, pancreatic ducts, bile ducts, and epididymis. WNK4 is also expressed in the specialized endothelium of the blood-brain barrier. These epithelia and endothelium all play important roles in Cl(-) transport. Because WNK4 is known to regulate renal Cl(-) handling, we tested WNK4's effect on the activity of mediators of epithelial Cl(-) flux whose extrarenal expression overlaps with WNK4. WNK4 proved to be a potent inhibitor of the activity of both the Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) and the Cl(-)/base exchanger SLC26A6 (CFEX) (>95% inhibition of NKCC1-mediated (86)Rb influx, P < 0.001; >80% inhibition of CFEX-mediated [(14)C] formate uptake, P < 0.001), mediators of Cl(-) flux across basolateral and apical membranes, respectively. In contrast, WNK4 showed no inhibition of pendrin, a related Cl(-)/base exchanger. These findings indicate a general role for WNK4 in the regulation of electrolyte flux in diverse epithelia. Moreover, they reveal that WNK4 regulates the activities of a diverse group of structurally unrelated ion channels, cotransporters, and exchangers.
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Affiliation(s)
- Kristopher T Kahle
- Department of Genetics, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
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90
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Delaloy C, Lu J, Houot AM, Disse-Nicodeme S, Gasc JM, Corvol P, Jeunemaitre X. Multiple promoters in the WNK1 gene: one controls expression of a kidney-specific kinase-defective isoform. Mol Cell Biol 2004; 23:9208-21. [PMID: 14645531 PMCID: PMC309643 DOI: 10.1128/mcb.23.24.9208-9221.2003] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
WNK1 is a serine-threonine kinase, the expression of which is affected in pseudohypoaldosteronism type II, a Mendelian form of arterial hypertension. We characterized human WNK1 transcripts to determine the molecular mechanisms governing WNK1 expression. We report the presence of two promoters generating two WNK1 isoforms with a complete kinase domain. Further variations are achieved by the use of two polyadenylation sites and tissue-specific splicing. We also determined the structure of a kidney-specific isoform regulated by a third promoter and starting at a novel exon. This transcript is kinase defective and has a predominant expression in the kidney compared to the other WNK1 isoforms, with, furthermore, a highly restricted expression profile in the distal convoluted tubule. We confirmed that the ubiquitous and kidney-specific promoters are functional in several cells lines and identified core promoters and regulatory elements. In particular, a strong enhancer element upstream from the kidney-specific exon seems specific to renal epithelial cells. Thus, control of human WNK1 gene expression of kinase-active or -deficient isoforms is mediated predominantly through the use of multiple transcription initiation sites and tissue-specific regulatory elements.
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Affiliation(s)
- Celine Delaloy
- INSERM U36, College de France, 11 place Marcelin Berthelot, 75005 Paris, France
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91
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Abstract
PURPOSE OF REVIEW The kidney plays an essential role in maintaining sodium and water balance, thereby controlling the volume and osmolarity of the extracellular body fluids, the blood volume and the blood pressure. The final adjustment of sodium and water reabsorption in the kidney takes place in cells of the distal part of the nephron in which a set of apical and basolateral transporters participate in vectorial sodium and water transport from the tubular lumen to the interstitium and, finally, to the general circulation. According to a current model, the activity and/or cell-surface expression of these transporters is/are under the control of a gene network composed of the hormonally regulated, as well as constitutively expressed, genes. It is proposed that this gene network may include new candidate genes for salt- and water-losing syndromes and for salt-sensitive hypertension. A new generation of functional genomics techniques have recently been applied to the characterization of this gene network. The purpose of this review is to summarize these studies and to discuss the potential of the different techniques for characterization of the renal transcriptome. RECENT FINDINGS Recently, DNA microarrays and serial analysis of gene expression have been applied to characterize the kidney transcriptome in different in-vivo and in-vitro models. In these studies, a set of new interesting genes potentially involved in the regulation of sodium and water reabsorption by the kidney have been identified and are currently under detailed investigation. SUMMARY Characterization of the kidney transcriptome is greatly expanding our knowledge of the gene networks involved in multiple kidney functions, including the maintenance of sodium and water homeostasis.
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Affiliation(s)
- Dmitri Firsov
- Institute of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.
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92
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La alteración renal es el principal mecanismo patogénico en el desarrollo de la hipertensión arterial. HIPERTENSION Y RIESGO VASCULAR 2004. [DOI: 10.1016/s1889-1837(04)71483-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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93
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Zambrowicz BP, Abuin A, Ramirez-Solis R, Richter LJ, Piggott J, BeltrandelRio H, Buxton EC, Edwards J, Finch RA, Friddle CJ, Gupta A, Hansen G, Hu Y, Huang W, Jaing C, Key BW, Kipp P, Kohlhauff B, Ma ZQ, Markesich D, Payne R, Potter DG, Qian N, Shaw J, Schrick J, Shi ZZ, Sparks MJ, Van Sligtenhorst I, Vogel P, Walke W, Xu N, Zhu Q, Person C, Sands AT. Wnk1 kinase deficiency lowers blood pressure in mice: a gene-trap screen to identify potential targets for therapeutic intervention. Proc Natl Acad Sci U S A 2003; 100:14109-14. [PMID: 14610273 PMCID: PMC283554 DOI: 10.1073/pnas.2336103100] [Citation(s) in RCA: 280] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2003] [Indexed: 11/18/2022] Open
Abstract
The availability of both the mouse and human genome sequences allows for the systematic discovery of human gene function through the use of the mouse as a model system. To accelerate the genetic determination of gene function, we have developed a sequence-tagged gene-trap library of >270,000 mouse embryonic stem cell clones representing mutations in approximately 60% of mammalian genes. Through the generation and phenotypic analysis of knockout mice from this resource, we are undertaking a functional screen to identify genes regulating physiological parameters such as blood pressure. As part of this screen, mice deficient for the Wnk1 kinase gene were generated and analyzed. Genetic studies in humans have shown that large intronic deletions in WNK1 lead to its overexpression and are responsible for pseudohypoaldosteronism type II, an autosomal dominant disorder characterized by hypertension, increased renal salt reabsorption, and impaired K+ and H+ excretion. Consistent with the human genetic studies, Wnk1 heterozygous mice displayed a significant decrease in blood pressure. Mice homozygous for the Wnk1 mutation died during embryonic development before day 13 of gestation. These results demonstrate that Wnk1 is a regulator of blood pressure critical for development and illustrate the utility of a functional screen driven by a sequence-based mutagenesis approach.
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Affiliation(s)
- Brian P Zambrowicz
- Lexicon Genetics, 8800 Technology Forest Place, The Woodlands, TX 77381, USA.
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94
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Kahle KT, Wilson FH, Leng Q, Lalioti MD, O'Connell AD, Dong K, Rapson AK, MacGregor GG, Giebisch G, Hebert SC, Lifton RP. WNK4 regulates the balance between renal NaCl reabsorption and K+ secretion. Nat Genet 2003; 35:372-6. [PMID: 14608358 DOI: 10.1038/ng1271] [Citation(s) in RCA: 314] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2003] [Accepted: 10/21/2003] [Indexed: 12/17/2022]
Abstract
A key question in systems biology is how diverse physiologic processes are integrated to produce global homeostasis. Genetic analysis can contribute by identifying genes that perturb this integration. One system orchestrates renal NaCl and K+ flux to achieve homeostasis of blood pressure and serum K+ concentration. Positional cloning implicated the serine-threonine kinase WNK4 in this process; clustered mutations in PRKWNK4, encoding WNK4, cause hypertension and hyperkalemia (pseudohypoaldosteronism type II, PHAII) by altering renal NaCl and K+ handling. Wild-type WNK4 inhibits the renal Na-Cl cotransporter (NCCT); mutations that cause PHAII relieve this inhibition. This explains the hypertension of PHAII but does not account for the hyperkalemia. By expression in Xenopus laevis oocytes, we show that WNK4 also inhibits the renal K+ channel ROMK. This inhibition is independent of WNK4 kinase activity and is mediated by clathrin-dependent endocytosis of ROMK, mechanisms distinct from those that characterize WNK4 inhibition of NCCT. Most notably, the same mutations in PRKWNK4 that relieve NCCT inhibition markedly increase inhibition of ROMK. These findings establish WNK4 as a multifunctional regulator of diverse ion transporters; moreover, they explain the pathophysiology of PHAII. They also identify WNK4 as a molecular switch that can vary the balance between NaCl reabsorption and K+ secretion to maintain integrated homeostasis.
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Affiliation(s)
- Kristopher T Kahle
- Howard Hughes Medical Institute, 300 Cedar Street, TAC S-341D, and Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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95
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O'Reilly M, Marshall E, Speirs HJL, Brown RW. WNK1, a Gene within a Novel Blood Pressure Control Pathway, Tissue-Specifically Generates Radically Different Isoforms with and without a Kinase Domain. J Am Soc Nephrol 2003; 14:2447-56. [PMID: 14514722 DOI: 10.1097/01.asn.0000089830.97681.3b] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
ABSTRACT. WNK1 is a member of a novel serine/threonine kinase family, With-No-K, (lysine). Intronic deletions in the encoding gene cause Gordon syndrome, an autosomal dominant, hypertensive, hyperkalemic disorder particularly responsive to thiazide diuretics, a first-line treatment in essential hypertension. To elucidate the novel WNK1 BP control pathway active in distal nephron, WNK1 expression in mouse was studied. It was found that WNK1 is highly expressed in testis > heart, lung, kidney, placenta > skeletal muscle, brain, and widely at low levels. Several WNK1 transcript classes are demonstrated, showing tissue-, developmental-, and nephron-segment–specific expression. Importantly, in kidney, the most prominent transcripts are smaller than elsewhere, having the first four exons replaced by an alternative 5′-exon, deleting the kinase domain, and showing strong distal nephron expression, whereas larger transcripts show low-level widespread distribution. Alternative splicing of exons 11 and 12 is prominent—for example, transcripts containing exon 11 are abundant in neural tissues, testis, and secondary renal transcripts but are predominantly absent in placenta. The transcriptional diversity generated by these events would produce proteins greatly differing in both structure and function. These findings help further define and clarify the role of WNK1 and the thiazide-responsive pathway relevant to essential hypertension in which it participates. E-mail: Roger.Brown@ed.ac.uk
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Affiliation(s)
- Michelle O'Reilly
- Molecular Endocrinology, University of Edinburgh, Edinburgh, Scotland
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96
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Abstract
The Henderson-Hasselbalch equation and the base excess have been used traditionally to describe the acid-base balance of the blood. In 1981, Stewart proposed a new model of acid-base balance based upon three variables, the "strong ion difference" (SID), the total weak acids (ATot), and the partial pressure of carbon dioxide (Pco2). Over 20 years later, Stewart's physiochemical model still remains largely unknown. In this review, we will present both the traditional and the Stewart models of acid-base balance and then derive each using an "ion equilibrium method." Modern theories of acid-base balance may be useful toward the understanding of complex acid-base disorders.
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Affiliation(s)
- Howard E Corey
- The Children's Kidney Center of New Jersey, Atlantic Health System, Morristown Memorial Hospital, Morristown, New Jersey 07962, USA.
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97
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Rossier BC. Negative regulators of sodium transport in the kidney: key factors in understanding salt-sensitive hypertension? J Clin Invest 2003; 111:947-50. [PMID: 12671041 PMCID: PMC152592 DOI: 10.1172/jci18232] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Bernard C Rossier
- Institut de Pharmacologie et de Toxicologie, Université de Lausanne, Lausanne, Switzerland.
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98
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Rossier BC. Negative regulators of sodium transport in the kidney: Key factors in understanding salt-sensitive hypertension? J Clin Invest 2003. [DOI: 10.1172/jci200318232] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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