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Wenhui Wang - One of the best experts on this subject based on the ideXlab platform.

  • Deletion of Kir5.1 Impairs Renal Ability to Excrete Potassium During Increased Dietary Potassium Intake
    Journal of The American Society of Nephrology, 2019
    Co-Authors: Peng Wu, Xiao-tong Su, Dan-dan Zhang, Wenhui Wang
    Abstract:

    Background The basolateral potassium channel in the distal convoluted tubule (DCT), comprising the inwardly rectifying potassium channel Kir4.1/Kir5.1 heterotetramer, plays a key role in mediating the effect of dietary potassium intake on the thiazide-sensitive NaCl cotransporter (NCC). The role of Kir5.1 (encoded by Kcnj16) in mediating effects of dietary potassium intake on the NCC and renal potassium excretion is unknown. Methods We used electrophysiology, renal clearance, and immunoblotting to study Kir4.1 in the DCT and NCC in Kir5.1 knockout (Kcnj16-/- ) and wild-type (Kcnj16+/+ ) mice fed with normal, high, or low potassium diets. Results We detected a 40-pS and 20-pS potassium channel in the basolateral membrane of the DCT in wild-type and knockout mice, respectively. Compared with wild-type, Kcnj16-/- mice fed a normal potassium diet had higher basolateral potassium conductance, a more negative DCT membrane potential, higher expression of phosphorylated NCC (pNCC) and total NCC (tNCC), and augmented thiazide-induced natriuresis. Neither high- nor low-potassium diets affected the basolateral DCT's potassium conductance and membrane potential in Kcnj16-/- mice. Although high potassium reduced and low potassium increased the expression of pNCC and tNCC in wild-type mice, these effects were absent in Kcnj16-/- mice. High potassium intake inhibited and low intake augmented thiazide-induced natriuresis in wild-type but not in Kcnj16-/- mice. Compared with wild-type, Kcnj16-/- mice with normal potassium intake had slightly lower plasma potassium but were more hyperkalemic with prolonged high potassium intake and more hypokalemic during potassium restriction. Conclusions Kir5.1 is essential for dietary potassium's effect on NCC and for maintaining potassium homeostasis.

  • KCNJ10 kir4 1 is expressed in the basolateral membrane of the cortical thick ascending limb
    American Journal of Physiology-renal Physiology, 2015
    Co-Authors: Dao Hong Lin, Lijun Wang, Chengbiao Zhang, Wenhui Wang
    Abstract:

    The aim of the present study is to examine the role of KCNJ10 (Kir.4.1) in contributing to the basolateral K conductance in the cortical thick ascending limb (cTAL) using KCNJ10+/+ wild-type (WT) a...

  • caveolin 1 deficiency inhibits the basolateral k channels in the distal convoluted tubule and impairs renal k and mg2 transport
    Journal of The American Society of Nephrology, 2015
    Co-Authors: Dao Hong Lin, Lijun Wang, Chengbiao Zhang, Wenhui Wang
    Abstract:

    KCNJ10 encodes the inwardly rectifying K + channel Kir4.1 in the basolateral membrane of the distal convoluted tubule (DCT) and is activated by c-Src. However, the regulation and function of this K + channel are incompletely characterized. Here, patch-clamp experiments in KCNJ10-transfected HEK293 cells demonstrated that c-Src–induced stimulation of KCNJ10 requires coexpression of caveolin-1 (cav-1), and immunostaining showed expression of cav-1 in the basolateral membrane of parvalbumin-positive DCT. Patch-clamp experiments detected a 40-pS inwardly rectifying K + channel, a heterotetramer of Kir4.1/Kir5.1, in the basolateral membrane of the early DCT (DCT1) in both wild-type (WT) and cav-1-knockout (KO) mice. However, the activity of this basolateral 40-pS K + channel was lower in KO mice than in WT mice. Moreover, the K + reversal potential (an indication of membrane potential) was less negative in the DCT1 of KO mice than in the DCT1 of WT mice. Western blot analysis demonstrated that cav-1 deficiency decreased the expression of the Na + /Cl – cotransporter and Ste20-proline-alanine-rich kinase (SPAK) but increased the expression of epithelial Na + channel- α . Furthermore, the urinary excretion of Mg 2+ and K + was significantly higher in KO mice than in WT mice, and KO mice developed hypomagnesemia, hypocalcemia, and hypokalemia. We conclude that disruption of cav-1 decreases basolateral K + channel activity and depolarizes the cell membrane potential in the DCT1 at least in part by suppressing the stimulatory effect of c-Src on KCNJ10. Furthermore, the decrease in KCNJ10 and Na + /Cl – cotransporter expression induced by cav-1 deficiency may underlie the compromised renal transport of Mg 2+ , Ca 2+ , and K + .

  • KCNJ10 determines the expression of the apical Na-Cl cotransporter (NCC) in the early distal convoluted tubule (DCT1)
    Proceedings of the National Academy of Sciences of the United States of America, 2014
    Co-Authors: Chengbiao Zhang, Ute I Scholl, Richard P Lifton, Lijun Wang, Dao Hong Lin, Junhui Zhang, Gerhard Giebisch, Wenhui Wang
    Abstract:

    The renal phenotype induced by loss-of-function mutations of inwardly rectifying potassium channel (Kir), KCNJ10 (Kir4.1), includes salt wasting, hypomagnesemia, metabolic alkalosis and hypokalemia. However, the mechanism by which Kir.4.1 mutations cause the tubulopathy is not completely understood. Here we demonstrate that KCNJ10 is a main contributor to the basolateral K conductance in the early distal convoluted tubule (DCT1) and determines the expression of the apical Na-Cl cotransporter (NCC) in the DCT. Immunostaining demonstrated KCNJ10 and Kcnj16 were expressed in the basolateral membrane of DCT, and patch-clamp studies detected a 40-pS K channel in the basolateral membrane of the DCT1 of p8/p10 wild-type KCNJ10+/+ mice (WT). This 40-pS K channel is absent in homozygous KCNJ10−/− (knockout) mice. The disruption of KCNJ10 almost completely eliminated the basolateral K conductance and decreased the negativity of the cell membrane potential in DCT1. Moreover, the lack of KCNJ10 decreased the basolateral Cl conductance, inhibited the expression of Ste20-related proline–alanine-rich kinase and diminished the apical NCC expression in DCT. We conclude that KCNJ10 plays a dominant role in determining the basolateral K conductance and membrane potential of DCT1 and that the basolateral K channel activity in the DCT determines the apical NCC expression possibly through a Ste20-related proline–alanine-rich kinase-dependent mechanism.

  • src family protein tyrosine kinase regulates the basolateral k channel in the distal convoluted tubule dct by phosphorylation of KCNJ10 protein
    Journal of Biological Chemistry, 2013
    Co-Authors: Lijun Wang, Dao Hong Lin, Chengbiao Zhang, Sherin Thomas, Kemeng Wang, Jesse Rinehart, Wenhui Wang
    Abstract:

    Abstract The loss of function of the basolateral K channels in the distal nephron causes electrolyte imbalance. The aim of this study is to examine the role of Src family protein tyrosine kinase (SFK) in regulating K channels in the basolateral membrane of the mouse initial distal convoluted tubule (DCT1). Single-channel recordings confirmed that the 40-picosiemen (pS) K channel was the only type of K channel in the basolateral membrane of DCT1. The suppression of SFK reversibly inhibited the basolateral 40-pS K channel activity in cell-attached patches and decreased the Ba2+-sensitive whole-cell K currents in DCT1. Inhibition of SFK also shifted the K reversal potential from −65 to −43 mV, suggesting a role of SFK in determining the membrane potential in DCT1. Western blot analysis showed that KCNJ10 (Kir4.1), a key component of the basolateral 40-pS K channel in DCT1, was a tyrosine-phosphorylated protein. LC/MS analysis further confirmed that SFK phosphorylated KCNJ10 at Tyr8 and Tyr9. The single-channel recording detected the activity of a 19-pS K channel in KCNJ10-transfected HEK293T cells and a 40-pS K channel in the cells transfected with KCNJ10+KCNJ16 (Kir.5.1) that form a heterotetramer in the basolateral membrane of the DCT. Mutation of Tyr9 did not alter the channel conductance of the homotetramer and heterotetramer. However, it decreased the whole-cell K currents, the probability of finding K channels, and surface expression of KCNJ10 in comparison to WT KCNJ10. We conclude that SFK stimulates the basolateral K channel activity in DCT1, at least partially, by phosphorylating Tyr9 on KCNJ10. We speculate that the modulation of tyrosine phosphorylation of KCNJ10 should play a role in regulating membrane transport function in DCT1.

Chengbiao Zhang - One of the best experts on this subject based on the ideXlab platform.

  • KCNJ10 kir4 1 is expressed in the basolateral membrane of the cortical thick ascending limb
    American Journal of Physiology-renal Physiology, 2015
    Co-Authors: Dao Hong Lin, Lijun Wang, Chengbiao Zhang, Wenhui Wang
    Abstract:

    The aim of the present study is to examine the role of KCNJ10 (Kir.4.1) in contributing to the basolateral K conductance in the cortical thick ascending limb (cTAL) using KCNJ10+/+ wild-type (WT) a...

  • caveolin 1 deficiency inhibits the basolateral k channels in the distal convoluted tubule and impairs renal k and mg2 transport
    Journal of The American Society of Nephrology, 2015
    Co-Authors: Dao Hong Lin, Lijun Wang, Chengbiao Zhang, Wenhui Wang
    Abstract:

    KCNJ10 encodes the inwardly rectifying K + channel Kir4.1 in the basolateral membrane of the distal convoluted tubule (DCT) and is activated by c-Src. However, the regulation and function of this K + channel are incompletely characterized. Here, patch-clamp experiments in KCNJ10-transfected HEK293 cells demonstrated that c-Src–induced stimulation of KCNJ10 requires coexpression of caveolin-1 (cav-1), and immunostaining showed expression of cav-1 in the basolateral membrane of parvalbumin-positive DCT. Patch-clamp experiments detected a 40-pS inwardly rectifying K + channel, a heterotetramer of Kir4.1/Kir5.1, in the basolateral membrane of the early DCT (DCT1) in both wild-type (WT) and cav-1-knockout (KO) mice. However, the activity of this basolateral 40-pS K + channel was lower in KO mice than in WT mice. Moreover, the K + reversal potential (an indication of membrane potential) was less negative in the DCT1 of KO mice than in the DCT1 of WT mice. Western blot analysis demonstrated that cav-1 deficiency decreased the expression of the Na + /Cl – cotransporter and Ste20-proline-alanine-rich kinase (SPAK) but increased the expression of epithelial Na + channel- α . Furthermore, the urinary excretion of Mg 2+ and K + was significantly higher in KO mice than in WT mice, and KO mice developed hypomagnesemia, hypocalcemia, and hypokalemia. We conclude that disruption of cav-1 decreases basolateral K + channel activity and depolarizes the cell membrane potential in the DCT1 at least in part by suppressing the stimulatory effect of c-Src on KCNJ10. Furthermore, the decrease in KCNJ10 and Na + /Cl – cotransporter expression induced by cav-1 deficiency may underlie the compromised renal transport of Mg 2+ , Ca 2+ , and K + .

  • KCNJ10 determines the expression of the apical Na-Cl cotransporter (NCC) in the early distal convoluted tubule (DCT1)
    Proceedings of the National Academy of Sciences of the United States of America, 2014
    Co-Authors: Chengbiao Zhang, Ute I Scholl, Richard P Lifton, Lijun Wang, Dao Hong Lin, Junhui Zhang, Gerhard Giebisch, Wenhui Wang
    Abstract:

    The renal phenotype induced by loss-of-function mutations of inwardly rectifying potassium channel (Kir), KCNJ10 (Kir4.1), includes salt wasting, hypomagnesemia, metabolic alkalosis and hypokalemia. However, the mechanism by which Kir.4.1 mutations cause the tubulopathy is not completely understood. Here we demonstrate that KCNJ10 is a main contributor to the basolateral K conductance in the early distal convoluted tubule (DCT1) and determines the expression of the apical Na-Cl cotransporter (NCC) in the DCT. Immunostaining demonstrated KCNJ10 and Kcnj16 were expressed in the basolateral membrane of DCT, and patch-clamp studies detected a 40-pS K channel in the basolateral membrane of the DCT1 of p8/p10 wild-type KCNJ10+/+ mice (WT). This 40-pS K channel is absent in homozygous KCNJ10−/− (knockout) mice. The disruption of KCNJ10 almost completely eliminated the basolateral K conductance and decreased the negativity of the cell membrane potential in DCT1. Moreover, the lack of KCNJ10 decreased the basolateral Cl conductance, inhibited the expression of Ste20-related proline–alanine-rich kinase and diminished the apical NCC expression in DCT. We conclude that KCNJ10 plays a dominant role in determining the basolateral K conductance and membrane potential of DCT1 and that the basolateral K channel activity in the DCT determines the apical NCC expression possibly through a Ste20-related proline–alanine-rich kinase-dependent mechanism.

  • src family protein tyrosine kinase regulates the basolateral k channel in the distal convoluted tubule dct by phosphorylation of KCNJ10 protein
    Journal of Biological Chemistry, 2013
    Co-Authors: Lijun Wang, Dao Hong Lin, Chengbiao Zhang, Sherin Thomas, Kemeng Wang, Jesse Rinehart, Wenhui Wang
    Abstract:

    Abstract The loss of function of the basolateral K channels in the distal nephron causes electrolyte imbalance. The aim of this study is to examine the role of Src family protein tyrosine kinase (SFK) in regulating K channels in the basolateral membrane of the mouse initial distal convoluted tubule (DCT1). Single-channel recordings confirmed that the 40-picosiemen (pS) K channel was the only type of K channel in the basolateral membrane of DCT1. The suppression of SFK reversibly inhibited the basolateral 40-pS K channel activity in cell-attached patches and decreased the Ba2+-sensitive whole-cell K currents in DCT1. Inhibition of SFK also shifted the K reversal potential from −65 to −43 mV, suggesting a role of SFK in determining the membrane potential in DCT1. Western blot analysis showed that KCNJ10 (Kir4.1), a key component of the basolateral 40-pS K channel in DCT1, was a tyrosine-phosphorylated protein. LC/MS analysis further confirmed that SFK phosphorylated KCNJ10 at Tyr8 and Tyr9. The single-channel recording detected the activity of a 19-pS K channel in KCNJ10-transfected HEK293T cells and a 40-pS K channel in the cells transfected with KCNJ10+KCNJ16 (Kir.5.1) that form a heterotetramer in the basolateral membrane of the DCT. Mutation of Tyr9 did not alter the channel conductance of the homotetramer and heterotetramer. However, it decreased the whole-cell K currents, the probability of finding K channels, and surface expression of KCNJ10 in comparison to WT KCNJ10. We conclude that SFK stimulates the basolateral K channel activity in DCT1, at least partially, by phosphorylating Tyr9 on KCNJ10. We speculate that the modulation of tyrosine phosphorylation of KCNJ10 should play a role in regulating membrane transport function in DCT1.

Markus Reichold - One of the best experts on this subject based on the ideXlab platform.

  • the salt wasting phenotype of east syndrome a disease with multifaceted symptoms linked to the KCNJ10 k channel
    Pflügers Archiv: European Journal of Physiology, 2011
    Co-Authors: Sascha Bandulik, Detlef Böckenhauer, Robert Kleta, Anselm A. Zdebik, Katharina Schmidt, Richard Warth, Evelyn Humberg, Markus Reichold
    Abstract:

    Mutations in the K+ channel gene KCNJ10 (Kir4.1) cause the autosomal recessive EAST syndrome which is characterized by epilepsy, ataxia, sensorineural deafness, and a salt-wasting tubulopathy. The renal salt-wasting pathology of EAST syndrome is caused by transport defects in the distal convoluted tubule where KCNJ10 plays a pivotal role as a basolateral K+ channel. This review on EAST syndrome outlines the molecular aspects of the physiology and pathophysiology of KCNJ10 in the distal convoluted tubule.

  • KCNJ10 gene mutations causing east syndrome epilepsy ataxia sensorineural deafness and tubulopathy disrupt channel function
    Proceedings of the National Academy of Sciences of the United States of America, 2010
    Co-Authors: Markus Reichold, Sascha Bandulik, Anselm A. Zdebik, E Lieberer, Christina Sterner, Markus Rapedius, Katharina Schmidt, Ines Tegtmeier, David Penton, Thomas Baukrowitz
    Abstract:

    Mutations of the KCNJ10 (Kir4.1) K+ channel underlie autosomal recessive epilepsy, ataxia, sensorineural deafness, and (a salt-wasting) renal tubulopathy (EAST) syndrome. We investigated the localization of KCNJ10 and the homologous KCNJ16 in kidney and the functional consequences of KCNJ10 mutations found in our patients with EAST syndrome. KCNJ10 and Kcnj16 were found in the basolateral membrane of mouse distal convoluted tubules, connecting tubules, and cortical collecting ducts. In the human kidney, KCNJ10 staining was additionally observed in the basolateral membrane of the cortical thick ascending limb of Henle's loop. EM of distal tubular cells of a patient with EAST syndrome showed reduced basal infoldings in this nephron segment, which likely reflects the morphological consequences of the impaired salt reabsorption capacity. When expressed in CHO and HEK293 cells, the KCNJ10 mutations R65P, G77R, and R175Q caused a marked impairment of channel function. R199X showed complete loss of function. Single-channel analysis revealed a strongly reduced mean open time. Qualitatively similar results were obtained with coexpression of KCNJ10/KCNJ16, suggesting a dominance of KCNJ10 function in native renal KCNJ10/KCNJ16 heteromers. The decrease in the current of R65P and R175Q was mainly caused by a remarkable shift of pH sensitivity to the alkaline range. In summary, EAST mutations of KCNJ10 lead to impaired channel function and structural changes in distal convoluted tubules. Intriguingly, the metabolic alkalosis present in patients carrying the R65P mutation possibly improves residual function of KCNJ10, which shows higher activity at alkaline pH.

Yohan Bignon - One of the best experts on this subject based on the ideXlab platform.

  • defective bicarbonate reabsorption in kir4 2 potassium channel deficient mice impairs acid base balance and ammonia excretion
    Kidney International, 2020
    Co-Authors: Yohan Bignon, Laurent Pinelli, Nadia Frachon, Olivier Lahuna, Lucile Figueres, Pascal Houillier
    Abstract:

    The kidneys excrete the daily acid load mainly by generating and excreting ammonia but the underlying molecular mechanisms are not fully understood. Here we evaluated the role of the inwardly rectifying potassium channel subunit Kir4.2 (Kcnj15 gene product) in this process. In mice, Kir4.2 was present exclusively at the basolateral membrane of proximal tubular cells and disruption of Kcnj15 caused a hyperchloremic metabolic acidosis associated with a reduced threshold for bicarbonate in the absence of a generalized proximal tubule dysfunction. Urinary ammonium excretion rates in Kcnj15- deleted mice were inappropriate to acidosis under basal and acid-loading conditions, and not related to a failure to acidify urine or a reduced expression of ammonia transporters in the collecting duct. In contrast, the expression of key proteins involved in ammonia metabolism and secretion by proximal cells, namely the glutamine transporter SNAT3, the phosphate-dependent glutaminase and phosphoenolpyruvate carboxykinase enzymes, and the sodium-proton exchanger NHE-3 was inappropriate in Kcnj15-deleted mice. Additionally, Kcnj15 deletion depolarized the proximal cell membrane by decreasing the barium-sensitive component of the potassium conductance and caused an intracellular alkalinization. Thus, the Kir4.2 potassium channel subunit is a newly recognized regulator of proximal ammonia metabolism. The kidney consequences of its loss of function in mice support the proposal for KCNJ15 as a molecular basis for human isolated proximal renal tubular acidosis.

  • defective bicarbonate reabsorption in kir4 2 potassium channel deficient mice impairs acid base balance and ammonia excretion
    Kidney International, 2020
    Co-Authors: Yohan Bignon, Laurent Pinelli, Nadia Frachon, Olivier Lahuna, Lucile Figueres, Pascal Houillier
    Abstract:

    The kidneys excrete the daily acid load mainly by generating and excreting ammonia but the underlying molecular mechanisms are not fully understood. Here we evaluated the role of the inwardly rectifying potassium channel subunit Kir4.2 (Kcnj15 gene product) in this process. In mice, Kir4.2 was present exclusively at the basolateral membrane of proximal tubular cells and disruption of Kcnj15 caused a hyperchloremic metabolic acidosis associated with a reduced threshold for bicarbonate in the absence of a generalized proximal tubule dysfunction. Urinary ammonium excretion rates in Kcnj15- deleted mice were inappropriate to acidosis under basal and acid-loading conditions, and not related to a failure to acidify urine or a reduced expression of ammonia transporters in the collecting duct. In contrast, the expression of key proteins involved in ammonia metabolism and secretion by proximal cells, namely the glutamine transporter SNAT3, the phosphate-dependent glutaminase and phosphoenolpyruvate carboxykinase enzymes, and the sodium-proton exchanger NHE-3 was inappropriate in Kcnj15-deleted mice. Additionally, Kcnj15 deletion depolarized the proximal cell membrane by decreasing the barium-sensitive component of the potassium conductance and caused an intracellular alkalinization. Thus, the Kir4.2 potassium channel subunit is a newly recognized regulator of proximal ammonia metabolism. The kidney consequences of its loss of function in mice support the proposal for KCNJ15 as a molecular basis for human isolated proximal renal tubular acidosis.

Anselm A. Zdebik - One of the best experts on this subject based on the ideXlab platform.

  • generation and validation of a zebrafish model of east epilepsy ataxia sensorineural deafness and tubulopathy syndrome
    Disease Models & Mechanisms, 2013
    Co-Authors: Fahad Mahmood, Detlef Böckenhauer, Robert Kleta, Horia Stanescu, Anselm A. Zdebik, Jonathan Tobin, Monika Mozere, Philip L Beales, Claire Russell
    Abstract:

    SUMMARY Recessive mutations in KCNJ10, which encodes an inwardly rectifying potassium channel, were recently identified as the cause of EAST syndrome, a severe and disabling multi-organ disorder consisting of epilepsy, ataxia, sensorineural deafness and tubulopathy that becomes clinically apparent with seizures in infancy. A KCNJ10 knockout mouse shows postnatal mortality and is therefore not suitable for drug discovery. Because zebrafish are ideal for in vivo screening for potential therapeutics, we tested whether KCNJ10 knockdown in zebrafish would fill this need. We cloned zebrafish KCNJ10 and demonstrated that its function is equivalent to that of human KCNJ10. We next injected splice- and translation-blocking KCNJ10 antisense morpholino oligonucleotides and reproduced the cardinal symptoms of EAST syndrome - ataxia, epilepsy and renal tubular defects. Several of these phenotypes could be assayed in an automated manner. We could rescue the morphant phenotype with complementary RNA (cRNA) encoding human wild-type KCNJ10, but not with cRNA encoding a KCNJ10 mutation identified in individuals with EAST syndrome. Our results suggest that zebrafish will be a valuable tool to screen for compounds that are potentially therapeutic for EAST syndrome or its individual symptoms. Knockdown

  • the salt wasting phenotype of east syndrome a disease with multifaceted symptoms linked to the KCNJ10 k channel
    Pflügers Archiv: European Journal of Physiology, 2011
    Co-Authors: Sascha Bandulik, Detlef Böckenhauer, Robert Kleta, Anselm A. Zdebik, Katharina Schmidt, Richard Warth, Evelyn Humberg, Markus Reichold
    Abstract:

    Mutations in the K+ channel gene KCNJ10 (Kir4.1) cause the autosomal recessive EAST syndrome which is characterized by epilepsy, ataxia, sensorineural deafness, and a salt-wasting tubulopathy. The renal salt-wasting pathology of EAST syndrome is caused by transport defects in the distal convoluted tubule where KCNJ10 plays a pivotal role as a basolateral K+ channel. This review on EAST syndrome outlines the molecular aspects of the physiology and pathophysiology of KCNJ10 in the distal convoluted tubule.

  • KCNJ10 gene mutations causing east syndrome epilepsy ataxia sensorineural deafness and tubulopathy disrupt channel function
    Proceedings of the National Academy of Sciences of the United States of America, 2010
    Co-Authors: Markus Reichold, Sascha Bandulik, Anselm A. Zdebik, E Lieberer, Christina Sterner, Markus Rapedius, Katharina Schmidt, Ines Tegtmeier, David Penton, Thomas Baukrowitz
    Abstract:

    Mutations of the KCNJ10 (Kir4.1) K+ channel underlie autosomal recessive epilepsy, ataxia, sensorineural deafness, and (a salt-wasting) renal tubulopathy (EAST) syndrome. We investigated the localization of KCNJ10 and the homologous KCNJ16 in kidney and the functional consequences of KCNJ10 mutations found in our patients with EAST syndrome. KCNJ10 and Kcnj16 were found in the basolateral membrane of mouse distal convoluted tubules, connecting tubules, and cortical collecting ducts. In the human kidney, KCNJ10 staining was additionally observed in the basolateral membrane of the cortical thick ascending limb of Henle's loop. EM of distal tubular cells of a patient with EAST syndrome showed reduced basal infoldings in this nephron segment, which likely reflects the morphological consequences of the impaired salt reabsorption capacity. When expressed in CHO and HEK293 cells, the KCNJ10 mutations R65P, G77R, and R175Q caused a marked impairment of channel function. R199X showed complete loss of function. Single-channel analysis revealed a strongly reduced mean open time. Qualitatively similar results were obtained with coexpression of KCNJ10/KCNJ16, suggesting a dominance of KCNJ10 function in native renal KCNJ10/KCNJ16 heteromers. The decrease in the current of R65P and R175Q was mainly caused by a remarkable shift of pH sensitivity to the alkaline range. In summary, EAST mutations of KCNJ10 lead to impaired channel function and structural changes in distal convoluted tubules. Intriguingly, the metabolic alkalosis present in patients carrying the R65P mutation possibly improves residual function of KCNJ10, which shows higher activity at alkaline pH.