Now showing 1 - 10 of 15
No Thumbnail Available
Publication

The European and Japanese eel NaCl cotransporters β exhibit chloride currents and are resistant to thiazide type diuretics

2022 , Moreno, Erika , Plata, Consuelo , Vázquez, Norma , Oropeza-Viveros, Dulce María , Pacheco Álvarez, Diana , Rojas-Vega, Lorena , Olin-Sandoval, Viridiana , Gamba, Gerardo

The thiazide-sensitive Na+-Cl- cotransporter (NCC) is the major pathway for salt reabsorption in the mammalian distal convoluted tubule, and the inhibition of its function with thiazides is widely used for the treatment of arterial hypertension. In mammals and teleosts, NCC is present as one ortholog that is mainly expressed in the kidney. One exception, however, is the eel, which has two genes encoding NCC. The eNCCα is located in the kidney and eNCCβ, which is present in the apical membrane of the rectum. Interestingly, the European eNCCβ functions as a Na+-Cl- cotransporter that is nevertheless resistant to thiazides and is not activated by low-chloride hypotonic stress. However, in the Japanese eel rectal sac, a thiazide-sensitive NaCl transport mechanism has been described. The protein sequences between eNCCβ and jNCCβ are 98% identical. Here, by site-directed mutagenesis, we transformed eNCCβ into jNCCβ. Our data showed that jNCCβ, similar to eNCCβ, is resistant to thiazides. In addition, both NCCβ proteins have high transport capacity with respect to their renal NCC orthologs and, in contrast to known NCCs, exhibit electrogenic properties that are reduced when residue I172 is substituted by A, G, or M. This is considered a key residue for the chloride ion-binding sites of NKCC and KCC. We conclude that NCCβ proteins are not sensitive to thiazides and have electrogenic properties dependent on Cl-, and site I172 is important for the function of NCCβ. ©American Journal of Physiology-Cell Physiology

No Thumbnail Available
Publication

Aspectos estructurales, funcionales y patológicos del cotransportador de NaCl sensible a tiazidas

2014-11 , Moreno, Erika , Pacheco Álvarez, Diana , Ríos Argaiz, Eduardo

El cotransportador de Na-Cl sensible a tiazidas (NCC o CST) es la principal vía de reabsorción de sal en el túbulo distal de la nefrona y es el sitio de acción de los diuréticos de tipo tiazida que, por su utilidad en el manejo de la hipertensión arterial, se encuentran dentro de los medicamentos más recetados en el mundo. El NCC es una proteína de suma importancia para la fisiología renal, ya que permite mantener la homeostasis de sal y agua en el organismo. Cuando suceden mutaciones inactivantes en el gen que codifica para este cotransportador se produce una enfermedad conocida como síndrome de Gitelman, el cual es un trastorno autosómico recesivo caracterizado clínicamente por hipotensión arterial, alcalosis metabólica, hipocalemia e hipocalciuria, lo que resalta la importancia de este gen en la regulación de la presión arterial y el equilibrio hidroelectrolítico. En este trabajo hacemos una breve revisión de los conocimientos que se tienen acerca de este cotransportador, con especial énfasis en la biología molecular, propiedades fisiológicas y aspectos patológicos del NCC. ©Revista de Investigación Clínica

No Thumbnail Available
Publication

WNK3 and WNK4 exhibit opposite sensitivity with respect to cell volume and intracellular chloride concentration

2020 , Pacheco Álvarez, Diana , Carrillo-Pérez, Diego Luis , Mercado, Adriana , Leyva Ríos, Karla , Moreno, Erika , Castañeda-Bueno, María , Elisa Hernández-Mercado , Vázquez, Norma , Gamba, Gerardo

Cation-coupled chloride cotransporters (CCC) play a role in modulating intracellular chloride concentration ([Cl-]i) and cell volume. Cell shrinkage and cell swelling are accompanied by an increase or decrease in [Cl-]i, respectively. Cell shrinkage and a decrease in [Cl-]i increase the activity of NKCCs (Na-K-Cl cotransporters: NKCC1, NKCC2, and Na-Cl) and inhibit the activity of KCCs (K-Cl cotransporters: KCC1 to KCC4), wheras cell swelling and an increase in [Cl-]i activate KCCs and inhibit NKCCs; thus, it is unlikely that the same kinase is responsible for both effects. WNK1 and WNK4 are chloride-sensitive kinases that modulate the activity of CCC in response to changes in [Cl-]i. Here, we showed that WNK3, another member of the serine-threonine kinase WNK family with known effects on CCC, is not sensitive to [Cl-]i but can be regulated by changes in extracellular tonicity. In contrast, WNK4 is highly sensitive to [Cl-]i but is not regulated by changes in cell volume. The activity of WNK3 toward NaCl cotransporter is not affected by eliminating the chloride-binding site of WNK3, further confirming that the kinase is not sensitive to chloride. Chimeric WNK3/WNK4 proteins were produced, and analysis of the chimeras suggests that sequences within the WNK’s carboxy-terminal end may modulate the chloride affinity. We propose that WNK3 is a cell volume-sensitive kinase that translates changes in cell volume into phosphorylation of CCC. Copyright © 2020 the American Physiological Society

No Thumbnail Available
Publication

Rare mutations in SLC12A1 and SLC12A3 protect against hypertension by reducing the activity of renal salt cotransporters

2011 , Acuña, Rocío , Martínez-de-la-Maza, Lilia , Ponce-Coria, José , Vázquez, Norma , Ortal-Vite, Penélope , Pacheco Álvarez, Diana , Bobadilla, Norma A. , Gamba, Gerardo

Objectives: Screening for variants in SLC12A1 and SLC12A3 genes, encoding the renal Na:Cl (NCC) and Na:K:2Cl (NKCC2) cotransporters, respectively, in 3125 members of the Framingham Heart Study (FHS) revealed that carrying a rare mutation in one of these genes was associated with a significant reduction in blood pressure, in the risk of arterial hypertension, and of death due to cardiovascular disease. Because near 60% of the rare mutations identified have not been related to Bartter's or Gitelman's disease, the consequence of such mutations on cotransporter activity is unknown. Methods: We used the heterologous expression system of Xenopus laevis oocytes, microinjected with wild-type or mutant NCC or NKCC2 cRNAs, to examine the effect of these inferred NCC and NKCC2 mutations on the cotransporters' functional properties. Cotransporter activity was defined as the diuretic-sensitive radioactive tracer uptake and response to known modulators was assessed. © Journal of Hypertension

No Thumbnail Available
Publication

WNK3-SPAK Interaction is Required for the Modulation of NCC and other Members of the SLC12 Family

2012 , Pacheco Álvarez, Diana , Vázquez, Norma , Castañeda-Bueno, María , De los Heros, Paola , Cortes-González, César , Moreno, Erika , Meade, Patricia , Bobadilla, Norma A. , Gamba, Gerardo

The serine/threonine with no lysine kinase 3 (WNK3) modulates the activity of the electroneutral cation-coupled chloride cotransporters (CCC) to promote Cl(-) influx and prevent Cl(-) efflux, thus fitting the profile for a putative "Cl(-)-sensing kinase". The Ste20-type kinases, SPAK/OSR1, become phosphorylated in response to reduction in intracellular chloride concentration and regulate the activity of NKCC1. Several studies have now shown that WNKs function upstream of SPAK/OSR1. This study was designed to analyze the role of WNK3-SPAK interaction in the regulation of CCCs with particular emphasis on NCC. In this study we used the functional expression system of Xenopus laevis oocytes to show that different SPAK binding sites in WNK3 ((241, 872, 1336)RFxV) are required for the kinase to have effects on CCCs. WNK3-F1337A no longer activated NKCC2, but the effects on NCC, NKCC1, and KCC4 were preserved. In contrast, the effects of WNK3 on these cotransporters were prevented in WNK3-F242A. The elimination of F873 had no consequence on WNK3 effects. WNK3 promoted NCC phosphorylation at threonine 58, even in the absence of the unique SPAK binding site of NCC, but this effect was abolished in the mutant WNK3-F242A. Thus, our data support the hypothesis that the effects of WNK3 upon NCC and other CCCs require the interaction and activation of the SPAK kinase. The effect is dependent on one of the three binding sites for SPAK that are present in WNK3, but not on the SPAK binding sites on the CCCs, which suggests that WNK3 is capable of binding both SPAK and CCCs to promote their phosphorylation.

No Thumbnail Available
Publication

Role of WNK Kinases in the Modulation of Cell Volume

2018 , De los Heros, Paola , Pacheco Álvarez, Diana , Gamba, Gerardo

Ion Transport across the cell membrane is required to maintain cell volume homeostasis. In response to changes in extracellular osmolarity, most cells activate specific metabolic or membrane-transport pathways to respond to cell swelling or shrinkage and return their volume to its normal resting state. This process involves the rapid adjustment of the activities of channels and transporters that mediate flux of K+, Na+, Cl-, and small organic osmolytes. Cation chloride cotransporters (CCCs) NKCCs and KCCs are a family of membrane proteins modulated by changes in cell volume and/or in the intracellular chloride concentration ([Cl-]i). Cell swelling triggers regulatory volume decrease (RVD), promoting solute and water efflux to restore normal cell volume. Swelling-activated KCCs mediate RVD in most cell types. In contrast, cell shrinkage triggers regulatory volume increase (RVI), which involves the activation of the NKCC1 cotransporter of the CCC family. Regulation of the CCCs during RVI and RVD by protein phosphorylation is a well-characterized mechanism, where WNK kinases and their downstream kinase substrates, SPAK and OSR1 constitute the essential phospho-regulators. WNKs-SPAK/OSR1-CCCs complex is required to regulate cell shrinkage-induced RVI or cell swelling-induced RVD via activating or inhibitory phosphorylation of NKCCs or KCCs, respectively. WNK1 and WNK4 kinases have been established as [Cl-]i sensors/regulators, while a role for WNK3 kinase as a cell volume-sensing kinase has emerged and is proposed in this chapter.

No Thumbnail Available
Publication

A CRAC-like motif in BAX sequence: Relationship with protein insertion and pore activity in liposomes

2011 , Martínez-Abundis, Eduardo , Correa, Francisco , Rodríguez, Emma , Soria-Castro, Elizabeth , Rodríguez-Zavala, José S. , Pacheco Álvarez, Diana , Zazueta, Cecilia

Several proteins that interact with cholesterol have a highly conserved sequence, corresponding to the cholesterol recognition/interaction amino acid consensus. Since cholesterol has been proposed to modulate both oligomerization and insertion of the pro-apoptotic protein BAX, we investigated the existence of such a motif in the BAX sequence. Residues 113 to 119 of the recombinant BAX α5-helix, LFYFASK, correspond with the sequence motif described for the consensus pattern, -L/V-(X)(1-5)-Y-(X)(1-5)-R/K. Functional characterization of the point mutations, K119A, Y115F, and L113A in BAX, was performed in liposomes supplemented with cholesterol, comparing binding, integration, and pore forming activities. Our results show that the mutations Y115F and L113A changed the cholesterol-dependent insertion observed in the wild type protein. In addition, substitutions in the BAX sequence modified the concentration dependency of carboxyfluorescein release in liposomes, although neither pore activity of the wild type or of any of the mutants significantly increased in cholesterol-enriched liposomes. Thus, while it is likely that the putative CRAC motif in BAX accounts for its enhanced insertion in cholesterol-enriched liposomes; the pore forming properties of BAX did not depend on cholesterol content in the membranes, albeit those mutations changed the pore channeling activity of the protein. Copyright © 2011 Elsevier B.V. All rights reserved. © Biochimica et Biophysica Acta (BBA) - Biomembranes

No Thumbnail Available
Publication

The European Eel NCCβ Gene Encodes a Thiazide-resistant Na-Cl Cotransporter

2016 , Moreno, Erika , Plata, Consuelo , Rodríguez-Gama, Alejandro , Argaiz, Eduardo R. , Vázquez, Norma , Leyva Ríos, Karla , Islas, León , Cutler, Christopher , Pacheco Álvarez, Diana , Mercado, Adriana , Cariño-Cortés, Raquel , Castañeda-Bueno, María , Gamba, Gerardo

The thiazide-sensitive Na-Cl cotransporter (NCC) is the major pathway for salt reabsorption in the mammalian distal convoluted tubule. NCC plays a key role in the regulation of blood pressure. Its inhibition with thiazides constitutes the primary baseline therapy for arterial hypertension. However, the thiazide-binding site in NCC is unknown. Mammals have only one gene encoding for NCC. The eel, however, contains a duplicate gene. NCCα is an ortholog of mammalian NCC and is expressed in the kidney. NCCβ is present in the apical membrane of the rectum. Here we cloned and functionally characterized NCCβ from the European eel. The cRNA encodes a 1043-amino acid membrane protein that, when expressed in Xenopus oocytes, functions as an Na-Cl cotransporter with two major characteristics, making it different from other known NCCs. First, eel NCCβ is resistant to thiazides. Single-point mutagenesis supports that the absence of thiazide inhibition is, at least in part, due to the substitution of a conserved serine for a cysteine at position 379. Second, NCCβ is not activated by low-chloride hypotonic stress, although the unique Ste20-related proline alanine-rich kinase (SPAK) binding site in the amino-terminal domain is conserved. Thus, NCCβ exhibits significant functional differences from NCCs that could be helpful in defining several aspects of the structure-function relationship of this important cotransporter. © 2016 ASBMB. Currently published by Elsevier Inc; originally published by American Society for Biochemistry and Molecular Biology.

No Thumbnail Available
Publication

Structure-function relationships in the sodium chloride cotransporter

2023 , Moreno, Erika , Pacheco Álvarez, Diana , Chávez-Canales, María , Elizalde, Stephanie , Leyva Ríos, Karla , Gamba, Gerardo

The thiazide sensitive Na+:Cl− cotransporter (NCC) is the principal via for salt reabsorption in the apical membrane of the distal convoluted tubule (DCT) in mammals and plays a fundamental role in managing blood pressure. The cotransporter is targeted by thiazide diuretics, a highly prescribed medication that is effective in treating arterial hypertension and edema. NCC was the first member of the electroneutral cation-coupled chloride cotransporter family to be identified at a molecular level. It was cloned from the urinary bladder of the Pseudopleuronectes americanus (winter flounder) 30 years ago. The structural topology, kinetic and pharmacology properties of NCC have been extensively studied, determining that the transmembrane domain (TM) coordinates ion and thiazide binding. Functional and mutational studies have discovered residues involved in the phosphorylation and glycosylation of NCC, particularly on the N-terminal domain, as well as the extracellular loop connected to TM7-8 (EL7-8). In the last decade, single-particle cryogenic electron microscopy (cryo-EM) has permitted the visualization of structures at high atomic resolution for six members of the SLC12 family (NCC, NKCC1, KCC1-KCC4). Cryo-EM insights of NCC confirm an inverted conformation of the TM1-5 and TM6-10 regions, a characteristic also found in the amino acid-polyamine-organocation (APC) superfamily, in which TM1 and TM6 clearly coordinate ion binding. The high-resolution structure also displays two glycosylation sites (N-406 and N-426) in EL7-8 that are essential for NCC expression and function. In this review, we briefly describe the studies related to the structure-function relationship of NCC, beginning with the first biochemical/functional studies up to the recent cryo-EM structure obtained, to acquire an overall view enriched with the structural and functional aspects of the cotransporter. Copyright © 2023 Moreno, Pacheco-Alvarez, Chávez-Canales, Elizalde, Leyva-Ríos and Gamba.

No Thumbnail Available
Publication

C-terminally truncated, kidney-specific variants of the WNK4 kinase lack several sites that regulate its activity

2018 , Murillo-de-Ozores, Adrián Rafael , Rodríguez Moya, Alejandro , Bazúa-Valenti, Silvana , Leyva Ríos, Karla , Vázquez, Norma , Pacheco Álvarez, Diana , Rosa-Velázquez, Inti A. de la , Wengi, Agnieszka , Stone, Kathryn L. , Junhui, Zhang , Loffing, Johannes , Lifton, Richard P. , Chao-Ling , Yang , Ellison, David H. , Gamba, Gerardo , Castañeda-Bueno, María

WNK lysine-deficient protein kinase 4 (WNK4) is an important regulator of renal salt handling. Mutations in its gene cause pseudohypoaldosteronism type II, mainly arising from overac-tivation of the renal Na/Cl cotransporter (NCC). In addition to full-length WNK4, we have observed faster migrating bands (between 95 and 130 kDa) in Western blots of kidney lysates. Therefore, we hypothesized that these could correspond to uncharacterized WNK4 variants. Here, using several WNK4 antibodies and WNK4/ mice as controls, we showed that these bands indeed correspond to short WNK4 variants that are not observed in other tissue lysates. LC-MS/MS confirmed these bands as WNK4 variants that lack C-terminal segments. In HEK293 cells, truncation of WNK4’s C terminus at several positions increased its kinase activity toward Ste20-related proline/ alanine-rich kinase (SPAK), unless the truncated segment included the SPAK-binding site. Of note, this gain-of-function effect was due to the loss of a protein phosphatase 1 (PP1)-bind-ing site in WNK4. Cotransfection with PP1 resulted in WNK4 dephosphorylation, an activity that was abrogated in the PP1-binding site WNK4 mutant. The electrophoretic mobility of the in vivo short variants of renal WNK4 suggested that they lack the SPAK-binding site and thus may not behave as constitutively active kinases toward SPAK. Finally, we show that at least one of the WNK4 short variants may be produced by proteolysis involving a Zn2-dependent metalloprotease, as recombinant full-length WNK4 was cleaved when incubated with kidney lysate. © 2018 American Society for Biochemistry and Molecular Biology Inc. All rights reserved.