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Shinichi Uchida - One of the best experts on this subject based on the ideXlab platform.
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wnk4 is indispensable for the pathogenesis of pseudohypoaldosteronism type ii caused by mutant klhl3
Biochemical and Biophysical Research Communications, 2017Co-Authors: Koichiro Susa, Daiei Takahashi, Eisei Sohara, Tatemitsu Rai, Tomokazu Okado, Shinichi UchidaAbstract:Abstract WNK-OSR1/SPAK-NCC signaling cascade is important for regulating salt balance and blood pressure. Activation of WNK-OSR1/SPAK-NaCl cotransporter (NCC) cascade increases sodium reabsorption in the kidney, leading to pseudohypoaldosteronism type II (PHA II) characterized by salt-sensitive hypertension and hyperkalemia. It has been previously demonstrated that the amount of phosphorylated and total NCC markedly decreased in WNK4 −/− mice, indicating that WNK4 plays a major role for activation of OSR1/SPAK-NCC signaling. However, it is unclear whether absence of WNK4 can be compensated by other WNK kinases. We recently reported that KLHL3 R528H/+ knock-in mice, a PHAII model, exhibited augmented activation of OSR1/SPAK-NCC signaling by increased protein levels of both WNK1 and WNK4 due to impaired protein degradation by the mutant KLHL3. In this study, we sought to determine the contribution of WNK4 to OSR1/SPAK-NCC signaling using an in vivo model which shows extremely increased WNK1 with absence of WNK4. We generated WNK4 −/− KLHL3 R528H/+ mice and WNK4 −/− KLHL3 R528H/R528H mice by crossing WNK4 −/− mice with KLHL3 R528H/+ mice. Thereafter, WNK-OSR1/SPAK-NCC phosphorylation signal cascade was examined in kidneys from these mice. As expected, both WNK4 −/− KLHL3 R528H/+ mice and WNK4 −/− KLHL3 R528H/R528H mice demonstrated increased WNK1 in the kidney, due to the KLHL3 mutation, and WNK4 deficiency. However, phosphorylation of SPAK and NCC at distal convoluted tubules were almost completely absent even in WNK4 −/− KLHL3 R528H/R528H mice. In conclusion, increased WNK1 was unable to compensate for WNK4 deficiency and phosphorylate the NCC, indicating that WNK4 is indispensable for the onset of PHAII.
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spak deficiency corrects pseudohypoaldosteronism ii caused by wnk4 mutation
PLOS ONE, 2013Co-Authors: Peiyi Chu, Sung-sen Yang, Shinichi Uchida, Sei Sasaki, Chihjen Cheng, Yuwei Fang, Tom Chau, Shihhua LinAbstract:Stimulation of the OSR1 (Oxidative stress-responsive kinase-1)/SPAK [STE20 (sterile 20)/SPS1-related proline/alanine-rich kinase]-NCC (Na+-Cl− cotransporter) signaling cascade plays an important role in the WNK [With-No-Lysine (K)] kinase 4 D561A knock-in mouse model of pseudohypoaldosteronism type II (PHA II) characterized by salt-sensitive hypertension and hyperkalemia. The aim of this study was to investigate the respective roles of OSR1 and Spak in the pathogenesis of PHA II in vivo. Wnk4D561A/+ mice were crossed with kidney tubule-specific (KSP) OSR1 knockout (KSP-OSR1−/−) and Spak knockout (Spak−/−) mice. Blood pressure, plasma and urine biochemistries, and the relevant protein expression in the kidneys were examined. Wnk4D561A/+, KSP-OSR1−/−, and Spak−/− mice recapitulated the phenotypes of PHA II, Bartter-like syndrome, and Gitelman syndrome, respectively. Wnk4D561A/+.KSP-OSR1−/− remained phenotypically PHA II while Wnk4D561A/+.Spak−/− mice became normotensive and lacked the PHA II phenotype. Phosphorylated Spak and Ncc were similarly increased in both Wnk4D561A/+ and Wnk4D561A/+.KSP-OSR1−/− mice while phosphorylated Ncc normalized in Wnk4D561A/+.Spak−/− mice. Furthermore, Wnk4D561A/+.KSP-OSR1−/− mice exhibited exaggerated salt excretion in response to thiazide diuretics while Wnk4D561A/+.Spak−/− mice exhibited normal responses. Wnk4D561A/+.Spak−/−.KSP-OSR1−/− triple mutant mice had low blood pressure and diminished phosphorylated Ncc. Both SPAK and OSR1 are important in the maintenance of blood pressure but activation of SPAK-NCC plays the dominant role in PHA II. SPAK may be a therapeutic target for disorders with salt-sensitive hypertension related to WNK4 activation.
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SPAK deficiency corrects pseudohypoaldosteronism II caused by WNK4 mutation
2013Co-Authors: Peiyi Chu, Shinichi Uchida, Chihjen Cheng, Yuwei Fang, Tom Chau, Sei SasakiAbstract:Stimulation of the OSR1 (Oxidative stress-responsive kinase-1)/SPAK [STE20 (sterile 20)/SPS1-related proline/alanine-rich kinase]-NCC (Na+-Cl2 cotransporter) signaling cascade plays an important role in the WNK [With-No-Lysine (K)] kinase 4 D561A knock-in mouse model of pseudohypoaldosteronism type II (PHA II) characterized by salt-sensitive hypertension and hyperkalemia. The aim of this study was to investigate the respective roles of OSR1 and Spak in the pathogenesis of PHA II in vivo. Wnk4D561A/+ mice were crossed with kidney tubule-specific (KSP) OSR1 knockout (KSP-OSR12/2) and Spak knockout (Spak2/2) mice. Blood pressure, plasma and urine biochemistries, and the relevant protein expression in the kidneys were examined. Wnk4D561A/+, KSP-OSR12/2, and Spak2/2 mice recapitulated the phenotypes of PHA II, Bartter-like syndrome, and Gitelman syndrome, respectively. Wnk4D561A/+.KSP-OSR12/2 remained phenotypically PHA II while Wnk4D561A/+.Spak2/2mice became normotensive and lacked the PHA II phenotype. Phosphorylated Spak and Ncc were similarly increased in both Wnk4D561A/+ and Wnk4D561A/+.KSP-OSR12/2 mice while phosphorylated Ncc normalized in Wnk4D561A/+.Spak2/2 mice. Furthermore, Wnk4D561A/+.KSP-OSR12/2 mice exhibited exaggerated salt excretion in response to thiazide diuretics while Wnk4D561A/+.Spak2/2 mice exhibited normal responses. Wnk4D561A/+.Spak2/2.KSP-OSR12/2 triple mutant mice had low blood pressure and diminished phosphorylated Ncc. Both SPAK and OSR1 are important in the maintenance of blood pressure but activation of SPAK-NCC plays the dominant role in PHA II. SPAK may be a therapeutic target for disorders with salt-sensitiv
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ask3 responds to osmotic stress and regulates blood pressure by suppressing wnk1 spak OSR1 signaling in the kidney
Nature Communications, 2012Co-Authors: Isao Naguro, Shinichi Uchida, Tsuyoshi Umeda, Yumie Kobayashi, Junichi Maruyama, Kazuki Hattori, Yutaka Shimizu, Keiichiro Kataoka, Shokei Kimmitsuyama, Alain VandewalleAbstract:Changes in the osmolality of body fluids pose a serious danger to cells and living organisms, which have developed cellular systems to sense and respond to osmotic stress and to maintain homoeostasis of body fluid. However, these processes are incompletely understood in mammals. Here we show that apoptosis signal-regulating kinase 3 (ASK3) is predominantly expressed in the kidney and alters its kinase activity bidirectionally in response to osmotic stress. We further demonstrate that ASK3 interacts with WNK1, mutation in which causes an inherited form of hypertension in humans. Knockdown of Ask3 by short interfering RNA enhances the activation of the WNK1-SPAK/OSR1 signalling pathway. Moreover, Ask3 knockout mice exhibit a hypertensive phenotype, in addition to hyperactivation of SPAK/OSR1 in renal tubules. Our results suggest that ASK3 is a unique bidirectional responder to osmotic stress and that it has a role in the control of blood pressure as an upstream suppressor of the WNK1-SPAK/OSR1 signalling pathway.
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wnk OSR1 spak ncc signal cascade has circadian rhythm dependent on aldosterone
Biochemical and Biophysical Research Communications, 2012Co-Authors: Koichiro Susa, Motoko Chiga, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Kiyoshi Isobe, Shinichi UchidaAbstract:Blood pressure and renal salt excretion show circadian rhythms. Recently, it has been clarified that clock genes regulate circadian rhythms of renal transporter expression in the kidney. Since we discovered the WNK-OSR1/SPAK-NaCl cotransporter (NCC) signal cascade, which is important for regulating salt balance and blood pressure, we have sought to determine whether NCC protein expression or phosphorylation shows diurnal rhythms in the mouse kidneys. Male C57BL/6J mice were sacrificed every 4h (at 20:00, 0:00, 4:00, 8:00, 12:00, and 16:00), and the expression and phosphorylation of WNK4, OSR1, SPAK, and NCC were determined by immunoblot. (Lights were turned on at 8:00, which was the start of the rest period, and turned off at 20:00, which was the start of the active period, since mice are nocturnal.) Although expression levels of each protein did not show diurnal rhythm, the phosphorylation levels of OSR1, SPAK, and NCC were increased around the start of the active period and decreased around the start of the rest period. Oral administration of eplerenone (10mg/day) attenuated the phosphorylation levels of these proteins and also diminished the diurnal rhythm of NCC phosphorylation. Thus, the activity of the WNK4-OSR1/SPAK-NCC cascade was shown to have a diurnal rhythm in the kidney that may be governed by aldosterone.
Dario R Alessi - One of the best experts on this subject based on the ideXlab platform.
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the wnk regulated spak OSR1 kinases directly phosphorylate and inhibit the k cl co transporters
Biochemical Journal, 2014Co-Authors: Paola De Los Heros, Dario R Alessi, Maria Deak, David G Campbell, Robert Gourlay, Thomas Macartney, Kristopher T Kahle, Jinwei ZhangAbstract:Precise homoeostasis of the intracellular concentration of Cl− is achieved via the co-ordinated activities of the Cl− influx and efflux. We demonstrate that the WNK (WNK lysine-deficient protein kinase)-activated SPAK (SPS1-related proline/alanine-rich kinase)/OSR1 (oxidative stress-responsive kinase 1) known to directly phosphorylate and stimulate the N[K]CCs (Na+–K+ ion co-transporters), also promote inhibition of the KCCs (K+–Cl− co-transporters) by directly phosphorylating a recently described C-terminal threonine residue conserved in all KCC isoforms [Site-2 (Thr1048)]. First, we demonstrate that SPAK and OSR1, in the presence of the MO25 regulatory subunit, robustly phosphorylates all KCC isoforms at Site-2 in vitro. Secondly, STOCK1S-50699, a WNK pathway inhibitor, suppresses SPAK/OSR1 activation and KCC3A Site-2 phosphorylation with similar efficiency. Thirdly, in ES (embryonic stem) cells lacking SPAK/OSR1 activity, endogenous phosphorylation of KCC isoforms at Site-2 is abolished and these cells display elevated basal activity of 86Rb+ uptake that was not markedly stimulated further by hypotonic high K+ conditions, consistent with KCC3A activation. Fourthly, a tight correlation exists between SPAK/OSR1 activity and the magnitude of KCC3A Site-2 phosphorylation. Lastly, a Site-2 alanine KCC3A mutant preventing SPAK/OSR1 phosphorylation exhibits increased activity. We also observe that KCCs are directly phosphorylated by SPAK/OSR1, at a novel Site-3 (Thr5 in KCC1/KCC3 and Thr6 in KCC2/KCC4), and a previously recognized KCC3-specific residue, Site-4 (Ser96). These data demonstrate that the WNK-regulated SPAK/OSR1 kinases directly phosphorylate the N[K]CCs and KCCs, promoting their stimulation and inhibition respectively. Given these reciprocal actions with anticipated net effects of increasing Cl− influx, we propose that the targeting of WNK–SPAK/OSR1 with kinase inhibitors might be a novel potent strategy to enhance cellular Cl− extrusion, with potential implications for the therapeutic modulation of epithelial and neuronal ion transport in human disease states.
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pi3k akt signaling pathway activates the wnk OSR1 spak ncc phosphorylation cascade in hyperinsulinemic db db mice
Hypertension, 2012Co-Authors: Hidenori Nishida, Dario R Alessi, Motoko Chiga, Naohiro Nomura, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Shinichi UchidaAbstract:Metabolic syndrome patients have insulin resistance, which causes hyperinsulinemia, which in turn causes aberrant increased renal sodium reabsorption. The precise mechanisms underlying this greater salt-sensitivity of hyperinsulinemic patients remain unclear. Abnormal activation of the recently-identified WNK kinase-OSR1/SPAK kinases-NCC transporter phosphorylation cascade results in the salt-sensitive hypertension of pseudohypoaldosteronism type II. Here, we report a study of renal WNK-OSR1/SPAK-NCC cascade activation in the db/db mouse model of hyperinsulinemic metabolic syndrome. Thiazide sensitivity was increased, suggesting greater activity of NCC in db/db mice. In fact, increased phosphorylation of OSR1/SPAK and NCC was observed. In both SpakT243A/+ and OSR1T185A/+ knock-in db/db mice, which carry mutations that disrupt the signal from WNK kinases, increased phosphorylation of NCC and elevated blood pressure were completely corrected, indicating that phosphorylation of SPAK and OSR1 by WNK kinases is required for the increased activation and phosphorylation of NCC in this model. Renal phosphorylated Akt was increased in db/db mice, suggesting that increased NCC phosphorylation is regulated by the PI3K/Akt signaling cascade in the kidney in response to hyperinsulinemia. A PI3K inhibitor (NVP-BEZ235) corrected the increased OSR1/SPAK-NCC phosphorylation. Another more specific PI3K inhibitor (GDC-0941) and an Akt inhibitor (MK-2206) also inhibited increased NCC phosphorylation. These results indicate that the PI3K/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in db/db mice. This mechanism may play a role in the pathogenesis of salt-sensitive hypertension in human hyperinsulinemic conditions such as the metabolic syndrome.
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phosphatidylinositol 3 kinase akt signaling pathway activates the wnk OSR1 spak ncc phosphorylation cascade in hyperinsulinemic db db micenovelty and significance
Hypertension, 2012Co-Authors: Hidenori Nishida, Dario R Alessi, Motoko Chiga, Naohiro Nomura, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Shinichi UchidaAbstract:Metabolic syndrome patients have insulin resistance, which causes hyperinsulinemia, which in turn causes aberrant increased renal sodium reabsorption. The precise mechanisms underlying this greater salt sensitivity of hyperinsulinemic patients remain unclear. Abnormal activation of the recently identified with-no-lysine kinase (WNK)-oxidative stress-responsive kinase 1 (OSR1)/STE20/SPS1-related proline/alanine-rich kinase (SPAK)-NaCl cotransporter (NCC) phosphorylation cascade results in the salt-sensitive hypertension of pseudohypoaldosteronism type II. Here, we report a study of renal WNK-OSR1/SPAK-NCC cascade activation in the db/db mouse model of hyperinsulinemic metabolic syndrome. Thiazide sensitivity was increased, suggesting greater activity of NCC in db/db mice. In fact, increased phosphorylation of OSR1/SPAK and NCC was observed. In both Spak T243A/+ and OSR1 T185A/+ knock-in db/db mice, which carry mutations that disrupt the signal from WNK kinases, increased phosphorylation of NCC and elevated blood pressure were completely corrected, indicating that phosphorylation of SPAK and OSR1 by WNK kinases is required for the increased activation and phosphorylation of NCC in this model. Renal phosphorylated Akt was increased in db/db mice, suggesting that increased NCC phosphorylation is regulated by the phosphatidylinositol 3-kinase/Akt signaling cascade in the kidney in response to hyperinsulinemia. A phosphatidylinositol 3-kinase inhibitor (NVP-BEZ235) corrected the increased OSR1/SPAK-NCC phosphorylation. Another more specific phosphatidylinositol 3-kinase inhibitor (GDC-0941) and an Akt inhibitor (MK-2206) also inhibited increased NCC phosphorylation. These results indicate that the phosphatidylinositol 3-kinase/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in db/db mice. This mechanism may play a role in the pathogenesis of salt-sensitive hypertension in human hyperinsulinemic conditions, such as the metabolic syndrome.
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phosphatidylinositol 3 kinase akt signaling pathway activates the wnk OSR1 spak ncc phosphorylation cascade in hyperinsulinemic db db mice
Hypertension, 2012Co-Authors: Hidenori Nishida, Dario R Alessi, Motoko Chiga, Naohiro Nomura, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Shinichi UchidaAbstract:Metabolic syndrome patients have insulin resistance, which causes hyperinsulinemia, which in turn causes aberrant increased renal sodium reabsorption. The precise mechanisms underlying this greater salt sensitivity of hyperinsulinemic patients remain unclear. Abnormal activation of the recently identified with-no-lysine kinase (WNK)-oxidative stress-responsive kinase 1 (OSR1)/STE20/SPS1-related proline/alanine-rich kinase (SPAK)-NaCl cotransporter (NCC) phosphorylation cascade results in the salt-sensitive hypertension of pseudohypoaldosteronism type II. Here, we report a study of renal WNK-OSR1/SPAK-NCC cascade activation in the db/db mouse model of hyperinsulinemic metabolic syndrome. Thiazide sensitivity was increased, suggesting greater activity of NCC in db/db mice. In fact, increased phosphorylation of OSR1/SPAK and NCC was observed. In both SpakT243A/+ and OSR1T185A/+ knock-in db/db mice, which carry mutations that disrupt the signal from WNK kinases, increased phosphorylation of NCC and elevated blood pressure were completely corrected, indicating that phosphorylation of SPAK and OSR1 by WNK kinases is required for the increased activation and phosphorylation of NCC in this model. Renal phosphorylated Akt was increased in db/db mice, suggesting that increased NCC phosphorylation is regulated by the phosphatidylinositol 3-kinase/Akt signaling cascade in the kidney in response to hyperinsulinemia. A phosphatidylinositol 3-kinase inhibitor (NVP-BEZ235) corrected the increased OSR1/SPAK-NCC phosphorylation. Another more specific phosphatidylinositol 3-kinase inhibitor (GDC-0941) and an Akt inhibitor (MK-2206) also inhibited increased NCC phosphorylation. These results indicate that the phosphatidylinositol 3-kinase/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in db/db mice. This mechanism may play a role in the pathogenesis of salt-sensitive hypertension in human hyperinsulinemic conditions, such as the metabolic syndrome.
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spak OSR1 regulate nkcc1 and wnk activity analysis of wnk isoform interactions and activation by t loop trans autophosphorylation
Biochemical Journal, 2012Co-Authors: Jacob Thastrup, Fatema H Rafiqi, Alberto C. Vitari, Maria Deak, Youcef Mehellou, Eulalia Pozoguisado, Dario R AlessiAbstract:Mutations in the WNK [with no lysine (K) kinase] family instigate hypertension and pain perception disorders. Of the four WNK isoforms, much of the focus has been on WNK1, which is activated in response to osmotic stress by phosphorylation of its T-loop residue (Ser382). WNK isoforms phosphorylate and activate the related SPAK (SPS1-related proline/alanine-rich kinase) and OSR1 (oxidative stress-responsive kinase 1) protein kinases. In the present study, we first describe the generation of double-knockin ES (embryonic stem) cells, where SPAK and OSR1 cannot be activated by WNK1. We establish that NKCC1 (Na+/K+/2Cl− co-transporter 1), a proposed target of the WNK pathway, is not phosphorylated or activated in a knockin that is deficient in SPAK/OSR1 activity. We also observe that activity of WNK1 and WNK3 are markedly elevated in the knockin cells, demonstrating that SPAK/OSR1 significantly influences WNK activity. Phosphorylation of another regulatory serine residue, Ser1261, in WNK1 is unaffected in knockin cells, indicating that this is not phosphorylated by SPAK/OSR1. We show that WNK isoforms interact via a C-terminal CCD (coiled-coil domain) and identify point mutations of conserved residues within this domain that ablate the ability of WNK isoforms to interact. Employing these mutants, we demonstrate that interaction of WNK isoforms is not essential for their T-loop phosphorylation and activation, at least for overexpressed WNK isoforms. Moreover, we finally establish that full-length WNK1, WNK2 and WNK3, but not WNK4, are capable of directly phosphorylating Ser382 of WNK1 in vitro. This supports the notion that T-loop phosphorylation of WNK isoforms is controlled by trans-autophosphorylation. These results provide novel insights into the WNK signal transduction pathway and provide genetic evidence confirming the essential role that SPAK/OSR1 play in controlling NKCC1 function. They also reveal a role in which the downstream SPAK/OSR1 enzymes markedly influence the activity of the upstream WNK activators. The knockin ES cells lacking SPAK/OSR1 activity will be useful in validating new targets of the WNK signalling pathway.
Eisei Sohara - One of the best experts on this subject based on the ideXlab platform.
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wnk4 is indispensable for the pathogenesis of pseudohypoaldosteronism type ii caused by mutant klhl3
Biochemical and Biophysical Research Communications, 2017Co-Authors: Koichiro Susa, Daiei Takahashi, Eisei Sohara, Tatemitsu Rai, Tomokazu Okado, Shinichi UchidaAbstract:Abstract WNK-OSR1/SPAK-NCC signaling cascade is important for regulating salt balance and blood pressure. Activation of WNK-OSR1/SPAK-NaCl cotransporter (NCC) cascade increases sodium reabsorption in the kidney, leading to pseudohypoaldosteronism type II (PHA II) characterized by salt-sensitive hypertension and hyperkalemia. It has been previously demonstrated that the amount of phosphorylated and total NCC markedly decreased in WNK4 −/− mice, indicating that WNK4 plays a major role for activation of OSR1/SPAK-NCC signaling. However, it is unclear whether absence of WNK4 can be compensated by other WNK kinases. We recently reported that KLHL3 R528H/+ knock-in mice, a PHAII model, exhibited augmented activation of OSR1/SPAK-NCC signaling by increased protein levels of both WNK1 and WNK4 due to impaired protein degradation by the mutant KLHL3. In this study, we sought to determine the contribution of WNK4 to OSR1/SPAK-NCC signaling using an in vivo model which shows extremely increased WNK1 with absence of WNK4. We generated WNK4 −/− KLHL3 R528H/+ mice and WNK4 −/− KLHL3 R528H/R528H mice by crossing WNK4 −/− mice with KLHL3 R528H/+ mice. Thereafter, WNK-OSR1/SPAK-NCC phosphorylation signal cascade was examined in kidneys from these mice. As expected, both WNK4 −/− KLHL3 R528H/+ mice and WNK4 −/− KLHL3 R528H/R528H mice demonstrated increased WNK1 in the kidney, due to the KLHL3 mutation, and WNK4 deficiency. However, phosphorylation of SPAK and NCC at distal convoluted tubules were almost completely absent even in WNK4 −/− KLHL3 R528H/R528H mice. In conclusion, increased WNK1 was unable to compensate for WNK4 deficiency and phosphorylate the NCC, indicating that WNK4 is indispensable for the onset of PHAII.
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wnk OSR1 spak ncc signal cascade has circadian rhythm dependent on aldosterone
Biochemical and Biophysical Research Communications, 2012Co-Authors: Koichiro Susa, Motoko Chiga, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Kiyoshi Isobe, Shinichi UchidaAbstract:Blood pressure and renal salt excretion show circadian rhythms. Recently, it has been clarified that clock genes regulate circadian rhythms of renal transporter expression in the kidney. Since we discovered the WNK-OSR1/SPAK-NaCl cotransporter (NCC) signal cascade, which is important for regulating salt balance and blood pressure, we have sought to determine whether NCC protein expression or phosphorylation shows diurnal rhythms in the mouse kidneys. Male C57BL/6J mice were sacrificed every 4h (at 20:00, 0:00, 4:00, 8:00, 12:00, and 16:00), and the expression and phosphorylation of WNK4, OSR1, SPAK, and NCC were determined by immunoblot. (Lights were turned on at 8:00, which was the start of the rest period, and turned off at 20:00, which was the start of the active period, since mice are nocturnal.) Although expression levels of each protein did not show diurnal rhythm, the phosphorylation levels of OSR1, SPAK, and NCC were increased around the start of the active period and decreased around the start of the rest period. Oral administration of eplerenone (10mg/day) attenuated the phosphorylation levels of these proteins and also diminished the diurnal rhythm of NCC phosphorylation. Thus, the activity of the WNK4-OSR1/SPAK-NCC cascade was shown to have a diurnal rhythm in the kidney that may be governed by aldosterone.
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pi3k akt signaling pathway activates the wnk OSR1 spak ncc phosphorylation cascade in hyperinsulinemic db db mice
Hypertension, 2012Co-Authors: Hidenori Nishida, Dario R Alessi, Motoko Chiga, Naohiro Nomura, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Shinichi UchidaAbstract:Metabolic syndrome patients have insulin resistance, which causes hyperinsulinemia, which in turn causes aberrant increased renal sodium reabsorption. The precise mechanisms underlying this greater salt-sensitivity of hyperinsulinemic patients remain unclear. Abnormal activation of the recently-identified WNK kinase-OSR1/SPAK kinases-NCC transporter phosphorylation cascade results in the salt-sensitive hypertension of pseudohypoaldosteronism type II. Here, we report a study of renal WNK-OSR1/SPAK-NCC cascade activation in the db/db mouse model of hyperinsulinemic metabolic syndrome. Thiazide sensitivity was increased, suggesting greater activity of NCC in db/db mice. In fact, increased phosphorylation of OSR1/SPAK and NCC was observed. In both SpakT243A/+ and OSR1T185A/+ knock-in db/db mice, which carry mutations that disrupt the signal from WNK kinases, increased phosphorylation of NCC and elevated blood pressure were completely corrected, indicating that phosphorylation of SPAK and OSR1 by WNK kinases is required for the increased activation and phosphorylation of NCC in this model. Renal phosphorylated Akt was increased in db/db mice, suggesting that increased NCC phosphorylation is regulated by the PI3K/Akt signaling cascade in the kidney in response to hyperinsulinemia. A PI3K inhibitor (NVP-BEZ235) corrected the increased OSR1/SPAK-NCC phosphorylation. Another more specific PI3K inhibitor (GDC-0941) and an Akt inhibitor (MK-2206) also inhibited increased NCC phosphorylation. These results indicate that the PI3K/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in db/db mice. This mechanism may play a role in the pathogenesis of salt-sensitive hypertension in human hyperinsulinemic conditions such as the metabolic syndrome.
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phosphatidylinositol 3 kinase akt signaling pathway activates the wnk OSR1 spak ncc phosphorylation cascade in hyperinsulinemic db db micenovelty and significance
Hypertension, 2012Co-Authors: Hidenori Nishida, Dario R Alessi, Motoko Chiga, Naohiro Nomura, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Shinichi UchidaAbstract:Metabolic syndrome patients have insulin resistance, which causes hyperinsulinemia, which in turn causes aberrant increased renal sodium reabsorption. The precise mechanisms underlying this greater salt sensitivity of hyperinsulinemic patients remain unclear. Abnormal activation of the recently identified with-no-lysine kinase (WNK)-oxidative stress-responsive kinase 1 (OSR1)/STE20/SPS1-related proline/alanine-rich kinase (SPAK)-NaCl cotransporter (NCC) phosphorylation cascade results in the salt-sensitive hypertension of pseudohypoaldosteronism type II. Here, we report a study of renal WNK-OSR1/SPAK-NCC cascade activation in the db/db mouse model of hyperinsulinemic metabolic syndrome. Thiazide sensitivity was increased, suggesting greater activity of NCC in db/db mice. In fact, increased phosphorylation of OSR1/SPAK and NCC was observed. In both Spak T243A/+ and OSR1 T185A/+ knock-in db/db mice, which carry mutations that disrupt the signal from WNK kinases, increased phosphorylation of NCC and elevated blood pressure were completely corrected, indicating that phosphorylation of SPAK and OSR1 by WNK kinases is required for the increased activation and phosphorylation of NCC in this model. Renal phosphorylated Akt was increased in db/db mice, suggesting that increased NCC phosphorylation is regulated by the phosphatidylinositol 3-kinase/Akt signaling cascade in the kidney in response to hyperinsulinemia. A phosphatidylinositol 3-kinase inhibitor (NVP-BEZ235) corrected the increased OSR1/SPAK-NCC phosphorylation. Another more specific phosphatidylinositol 3-kinase inhibitor (GDC-0941) and an Akt inhibitor (MK-2206) also inhibited increased NCC phosphorylation. These results indicate that the phosphatidylinositol 3-kinase/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in db/db mice. This mechanism may play a role in the pathogenesis of salt-sensitive hypertension in human hyperinsulinemic conditions, such as the metabolic syndrome.
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phosphatidylinositol 3 kinase akt signaling pathway activates the wnk OSR1 spak ncc phosphorylation cascade in hyperinsulinemic db db mice
Hypertension, 2012Co-Authors: Hidenori Nishida, Dario R Alessi, Motoko Chiga, Naohiro Nomura, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Shinichi UchidaAbstract:Metabolic syndrome patients have insulin resistance, which causes hyperinsulinemia, which in turn causes aberrant increased renal sodium reabsorption. The precise mechanisms underlying this greater salt sensitivity of hyperinsulinemic patients remain unclear. Abnormal activation of the recently identified with-no-lysine kinase (WNK)-oxidative stress-responsive kinase 1 (OSR1)/STE20/SPS1-related proline/alanine-rich kinase (SPAK)-NaCl cotransporter (NCC) phosphorylation cascade results in the salt-sensitive hypertension of pseudohypoaldosteronism type II. Here, we report a study of renal WNK-OSR1/SPAK-NCC cascade activation in the db/db mouse model of hyperinsulinemic metabolic syndrome. Thiazide sensitivity was increased, suggesting greater activity of NCC in db/db mice. In fact, increased phosphorylation of OSR1/SPAK and NCC was observed. In both SpakT243A/+ and OSR1T185A/+ knock-in db/db mice, which carry mutations that disrupt the signal from WNK kinases, increased phosphorylation of NCC and elevated blood pressure were completely corrected, indicating that phosphorylation of SPAK and OSR1 by WNK kinases is required for the increased activation and phosphorylation of NCC in this model. Renal phosphorylated Akt was increased in db/db mice, suggesting that increased NCC phosphorylation is regulated by the phosphatidylinositol 3-kinase/Akt signaling cascade in the kidney in response to hyperinsulinemia. A phosphatidylinositol 3-kinase inhibitor (NVP-BEZ235) corrected the increased OSR1/SPAK-NCC phosphorylation. Another more specific phosphatidylinositol 3-kinase inhibitor (GDC-0941) and an Akt inhibitor (MK-2206) also inhibited increased NCC phosphorylation. These results indicate that the phosphatidylinositol 3-kinase/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in db/db mice. This mechanism may play a role in the pathogenesis of salt-sensitive hypertension in human hyperinsulinemic conditions, such as the metabolic syndrome.
Sei Sasaki - One of the best experts on this subject based on the ideXlab platform.
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spak deficiency corrects pseudohypoaldosteronism ii caused by wnk4 mutation
PLOS ONE, 2013Co-Authors: Peiyi Chu, Sung-sen Yang, Shinichi Uchida, Sei Sasaki, Chihjen Cheng, Yuwei Fang, Tom Chau, Shihhua LinAbstract:Stimulation of the OSR1 (Oxidative stress-responsive kinase-1)/SPAK [STE20 (sterile 20)/SPS1-related proline/alanine-rich kinase]-NCC (Na+-Cl− cotransporter) signaling cascade plays an important role in the WNK [With-No-Lysine (K)] kinase 4 D561A knock-in mouse model of pseudohypoaldosteronism type II (PHA II) characterized by salt-sensitive hypertension and hyperkalemia. The aim of this study was to investigate the respective roles of OSR1 and Spak in the pathogenesis of PHA II in vivo. Wnk4D561A/+ mice were crossed with kidney tubule-specific (KSP) OSR1 knockout (KSP-OSR1−/−) and Spak knockout (Spak−/−) mice. Blood pressure, plasma and urine biochemistries, and the relevant protein expression in the kidneys were examined. Wnk4D561A/+, KSP-OSR1−/−, and Spak−/− mice recapitulated the phenotypes of PHA II, Bartter-like syndrome, and Gitelman syndrome, respectively. Wnk4D561A/+.KSP-OSR1−/− remained phenotypically PHA II while Wnk4D561A/+.Spak−/− mice became normotensive and lacked the PHA II phenotype. Phosphorylated Spak and Ncc were similarly increased in both Wnk4D561A/+ and Wnk4D561A/+.KSP-OSR1−/− mice while phosphorylated Ncc normalized in Wnk4D561A/+.Spak−/− mice. Furthermore, Wnk4D561A/+.KSP-OSR1−/− mice exhibited exaggerated salt excretion in response to thiazide diuretics while Wnk4D561A/+.Spak−/− mice exhibited normal responses. Wnk4D561A/+.Spak−/−.KSP-OSR1−/− triple mutant mice had low blood pressure and diminished phosphorylated Ncc. Both SPAK and OSR1 are important in the maintenance of blood pressure but activation of SPAK-NCC plays the dominant role in PHA II. SPAK may be a therapeutic target for disorders with salt-sensitive hypertension related to WNK4 activation.
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SPAK deficiency corrects pseudohypoaldosteronism II caused by WNK4 mutation
2013Co-Authors: Peiyi Chu, Shinichi Uchida, Chihjen Cheng, Yuwei Fang, Tom Chau, Sei SasakiAbstract:Stimulation of the OSR1 (Oxidative stress-responsive kinase-1)/SPAK [STE20 (sterile 20)/SPS1-related proline/alanine-rich kinase]-NCC (Na+-Cl2 cotransporter) signaling cascade plays an important role in the WNK [With-No-Lysine (K)] kinase 4 D561A knock-in mouse model of pseudohypoaldosteronism type II (PHA II) characterized by salt-sensitive hypertension and hyperkalemia. The aim of this study was to investigate the respective roles of OSR1 and Spak in the pathogenesis of PHA II in vivo. Wnk4D561A/+ mice were crossed with kidney tubule-specific (KSP) OSR1 knockout (KSP-OSR12/2) and Spak knockout (Spak2/2) mice. Blood pressure, plasma and urine biochemistries, and the relevant protein expression in the kidneys were examined. Wnk4D561A/+, KSP-OSR12/2, and Spak2/2 mice recapitulated the phenotypes of PHA II, Bartter-like syndrome, and Gitelman syndrome, respectively. Wnk4D561A/+.KSP-OSR12/2 remained phenotypically PHA II while Wnk4D561A/+.Spak2/2mice became normotensive and lacked the PHA II phenotype. Phosphorylated Spak and Ncc were similarly increased in both Wnk4D561A/+ and Wnk4D561A/+.KSP-OSR12/2 mice while phosphorylated Ncc normalized in Wnk4D561A/+.Spak2/2 mice. Furthermore, Wnk4D561A/+.KSP-OSR12/2 mice exhibited exaggerated salt excretion in response to thiazide diuretics while Wnk4D561A/+.Spak2/2 mice exhibited normal responses. Wnk4D561A/+.Spak2/2.KSP-OSR12/2 triple mutant mice had low blood pressure and diminished phosphorylated Ncc. Both SPAK and OSR1 are important in the maintenance of blood pressure but activation of SPAK-NCC plays the dominant role in PHA II. SPAK may be a therapeutic target for disorders with salt-sensitiv
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wnk OSR1 spak ncc signal cascade has circadian rhythm dependent on aldosterone
Biochemical and Biophysical Research Communications, 2012Co-Authors: Koichiro Susa, Motoko Chiga, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Kiyoshi Isobe, Shinichi UchidaAbstract:Blood pressure and renal salt excretion show circadian rhythms. Recently, it has been clarified that clock genes regulate circadian rhythms of renal transporter expression in the kidney. Since we discovered the WNK-OSR1/SPAK-NaCl cotransporter (NCC) signal cascade, which is important for regulating salt balance and blood pressure, we have sought to determine whether NCC protein expression or phosphorylation shows diurnal rhythms in the mouse kidneys. Male C57BL/6J mice were sacrificed every 4h (at 20:00, 0:00, 4:00, 8:00, 12:00, and 16:00), and the expression and phosphorylation of WNK4, OSR1, SPAK, and NCC were determined by immunoblot. (Lights were turned on at 8:00, which was the start of the rest period, and turned off at 20:00, which was the start of the active period, since mice are nocturnal.) Although expression levels of each protein did not show diurnal rhythm, the phosphorylation levels of OSR1, SPAK, and NCC were increased around the start of the active period and decreased around the start of the rest period. Oral administration of eplerenone (10mg/day) attenuated the phosphorylation levels of these proteins and also diminished the diurnal rhythm of NCC phosphorylation. Thus, the activity of the WNK4-OSR1/SPAK-NCC cascade was shown to have a diurnal rhythm in the kidney that may be governed by aldosterone.
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pi3k akt signaling pathway activates the wnk OSR1 spak ncc phosphorylation cascade in hyperinsulinemic db db mice
Hypertension, 2012Co-Authors: Hidenori Nishida, Dario R Alessi, Motoko Chiga, Naohiro Nomura, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Shinichi UchidaAbstract:Metabolic syndrome patients have insulin resistance, which causes hyperinsulinemia, which in turn causes aberrant increased renal sodium reabsorption. The precise mechanisms underlying this greater salt-sensitivity of hyperinsulinemic patients remain unclear. Abnormal activation of the recently-identified WNK kinase-OSR1/SPAK kinases-NCC transporter phosphorylation cascade results in the salt-sensitive hypertension of pseudohypoaldosteronism type II. Here, we report a study of renal WNK-OSR1/SPAK-NCC cascade activation in the db/db mouse model of hyperinsulinemic metabolic syndrome. Thiazide sensitivity was increased, suggesting greater activity of NCC in db/db mice. In fact, increased phosphorylation of OSR1/SPAK and NCC was observed. In both SpakT243A/+ and OSR1T185A/+ knock-in db/db mice, which carry mutations that disrupt the signal from WNK kinases, increased phosphorylation of NCC and elevated blood pressure were completely corrected, indicating that phosphorylation of SPAK and OSR1 by WNK kinases is required for the increased activation and phosphorylation of NCC in this model. Renal phosphorylated Akt was increased in db/db mice, suggesting that increased NCC phosphorylation is regulated by the PI3K/Akt signaling cascade in the kidney in response to hyperinsulinemia. A PI3K inhibitor (NVP-BEZ235) corrected the increased OSR1/SPAK-NCC phosphorylation. Another more specific PI3K inhibitor (GDC-0941) and an Akt inhibitor (MK-2206) also inhibited increased NCC phosphorylation. These results indicate that the PI3K/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in db/db mice. This mechanism may play a role in the pathogenesis of salt-sensitive hypertension in human hyperinsulinemic conditions such as the metabolic syndrome.
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phosphatidylinositol 3 kinase akt signaling pathway activates the wnk OSR1 spak ncc phosphorylation cascade in hyperinsulinemic db db micenovelty and significance
Hypertension, 2012Co-Authors: Hidenori Nishida, Dario R Alessi, Motoko Chiga, Naohiro Nomura, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Shinichi UchidaAbstract:Metabolic syndrome patients have insulin resistance, which causes hyperinsulinemia, which in turn causes aberrant increased renal sodium reabsorption. The precise mechanisms underlying this greater salt sensitivity of hyperinsulinemic patients remain unclear. Abnormal activation of the recently identified with-no-lysine kinase (WNK)-oxidative stress-responsive kinase 1 (OSR1)/STE20/SPS1-related proline/alanine-rich kinase (SPAK)-NaCl cotransporter (NCC) phosphorylation cascade results in the salt-sensitive hypertension of pseudohypoaldosteronism type II. Here, we report a study of renal WNK-OSR1/SPAK-NCC cascade activation in the db/db mouse model of hyperinsulinemic metabolic syndrome. Thiazide sensitivity was increased, suggesting greater activity of NCC in db/db mice. In fact, increased phosphorylation of OSR1/SPAK and NCC was observed. In both Spak T243A/+ and OSR1 T185A/+ knock-in db/db mice, which carry mutations that disrupt the signal from WNK kinases, increased phosphorylation of NCC and elevated blood pressure were completely corrected, indicating that phosphorylation of SPAK and OSR1 by WNK kinases is required for the increased activation and phosphorylation of NCC in this model. Renal phosphorylated Akt was increased in db/db mice, suggesting that increased NCC phosphorylation is regulated by the phosphatidylinositol 3-kinase/Akt signaling cascade in the kidney in response to hyperinsulinemia. A phosphatidylinositol 3-kinase inhibitor (NVP-BEZ235) corrected the increased OSR1/SPAK-NCC phosphorylation. Another more specific phosphatidylinositol 3-kinase inhibitor (GDC-0941) and an Akt inhibitor (MK-2206) also inhibited increased NCC phosphorylation. These results indicate that the phosphatidylinositol 3-kinase/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in db/db mice. This mechanism may play a role in the pathogenesis of salt-sensitive hypertension in human hyperinsulinemic conditions, such as the metabolic syndrome.
Tatemitsu Rai - One of the best experts on this subject based on the ideXlab platform.
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wnk4 is indispensable for the pathogenesis of pseudohypoaldosteronism type ii caused by mutant klhl3
Biochemical and Biophysical Research Communications, 2017Co-Authors: Koichiro Susa, Daiei Takahashi, Eisei Sohara, Tatemitsu Rai, Tomokazu Okado, Shinichi UchidaAbstract:Abstract WNK-OSR1/SPAK-NCC signaling cascade is important for regulating salt balance and blood pressure. Activation of WNK-OSR1/SPAK-NaCl cotransporter (NCC) cascade increases sodium reabsorption in the kidney, leading to pseudohypoaldosteronism type II (PHA II) characterized by salt-sensitive hypertension and hyperkalemia. It has been previously demonstrated that the amount of phosphorylated and total NCC markedly decreased in WNK4 −/− mice, indicating that WNK4 plays a major role for activation of OSR1/SPAK-NCC signaling. However, it is unclear whether absence of WNK4 can be compensated by other WNK kinases. We recently reported that KLHL3 R528H/+ knock-in mice, a PHAII model, exhibited augmented activation of OSR1/SPAK-NCC signaling by increased protein levels of both WNK1 and WNK4 due to impaired protein degradation by the mutant KLHL3. In this study, we sought to determine the contribution of WNK4 to OSR1/SPAK-NCC signaling using an in vivo model which shows extremely increased WNK1 with absence of WNK4. We generated WNK4 −/− KLHL3 R528H/+ mice and WNK4 −/− KLHL3 R528H/R528H mice by crossing WNK4 −/− mice with KLHL3 R528H/+ mice. Thereafter, WNK-OSR1/SPAK-NCC phosphorylation signal cascade was examined in kidneys from these mice. As expected, both WNK4 −/− KLHL3 R528H/+ mice and WNK4 −/− KLHL3 R528H/R528H mice demonstrated increased WNK1 in the kidney, due to the KLHL3 mutation, and WNK4 deficiency. However, phosphorylation of SPAK and NCC at distal convoluted tubules were almost completely absent even in WNK4 −/− KLHL3 R528H/R528H mice. In conclusion, increased WNK1 was unable to compensate for WNK4 deficiency and phosphorylate the NCC, indicating that WNK4 is indispensable for the onset of PHAII.
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wnk OSR1 spak ncc signal cascade has circadian rhythm dependent on aldosterone
Biochemical and Biophysical Research Communications, 2012Co-Authors: Koichiro Susa, Motoko Chiga, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Kiyoshi Isobe, Shinichi UchidaAbstract:Blood pressure and renal salt excretion show circadian rhythms. Recently, it has been clarified that clock genes regulate circadian rhythms of renal transporter expression in the kidney. Since we discovered the WNK-OSR1/SPAK-NaCl cotransporter (NCC) signal cascade, which is important for regulating salt balance and blood pressure, we have sought to determine whether NCC protein expression or phosphorylation shows diurnal rhythms in the mouse kidneys. Male C57BL/6J mice were sacrificed every 4h (at 20:00, 0:00, 4:00, 8:00, 12:00, and 16:00), and the expression and phosphorylation of WNK4, OSR1, SPAK, and NCC were determined by immunoblot. (Lights were turned on at 8:00, which was the start of the rest period, and turned off at 20:00, which was the start of the active period, since mice are nocturnal.) Although expression levels of each protein did not show diurnal rhythm, the phosphorylation levels of OSR1, SPAK, and NCC were increased around the start of the active period and decreased around the start of the rest period. Oral administration of eplerenone (10mg/day) attenuated the phosphorylation levels of these proteins and also diminished the diurnal rhythm of NCC phosphorylation. Thus, the activity of the WNK4-OSR1/SPAK-NCC cascade was shown to have a diurnal rhythm in the kidney that may be governed by aldosterone.
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pi3k akt signaling pathway activates the wnk OSR1 spak ncc phosphorylation cascade in hyperinsulinemic db db mice
Hypertension, 2012Co-Authors: Hidenori Nishida, Dario R Alessi, Motoko Chiga, Naohiro Nomura, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Shinichi UchidaAbstract:Metabolic syndrome patients have insulin resistance, which causes hyperinsulinemia, which in turn causes aberrant increased renal sodium reabsorption. The precise mechanisms underlying this greater salt-sensitivity of hyperinsulinemic patients remain unclear. Abnormal activation of the recently-identified WNK kinase-OSR1/SPAK kinases-NCC transporter phosphorylation cascade results in the salt-sensitive hypertension of pseudohypoaldosteronism type II. Here, we report a study of renal WNK-OSR1/SPAK-NCC cascade activation in the db/db mouse model of hyperinsulinemic metabolic syndrome. Thiazide sensitivity was increased, suggesting greater activity of NCC in db/db mice. In fact, increased phosphorylation of OSR1/SPAK and NCC was observed. In both SpakT243A/+ and OSR1T185A/+ knock-in db/db mice, which carry mutations that disrupt the signal from WNK kinases, increased phosphorylation of NCC and elevated blood pressure were completely corrected, indicating that phosphorylation of SPAK and OSR1 by WNK kinases is required for the increased activation and phosphorylation of NCC in this model. Renal phosphorylated Akt was increased in db/db mice, suggesting that increased NCC phosphorylation is regulated by the PI3K/Akt signaling cascade in the kidney in response to hyperinsulinemia. A PI3K inhibitor (NVP-BEZ235) corrected the increased OSR1/SPAK-NCC phosphorylation. Another more specific PI3K inhibitor (GDC-0941) and an Akt inhibitor (MK-2206) also inhibited increased NCC phosphorylation. These results indicate that the PI3K/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in db/db mice. This mechanism may play a role in the pathogenesis of salt-sensitive hypertension in human hyperinsulinemic conditions such as the metabolic syndrome.
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phosphatidylinositol 3 kinase akt signaling pathway activates the wnk OSR1 spak ncc phosphorylation cascade in hyperinsulinemic db db micenovelty and significance
Hypertension, 2012Co-Authors: Hidenori Nishida, Dario R Alessi, Motoko Chiga, Naohiro Nomura, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Shinichi UchidaAbstract:Metabolic syndrome patients have insulin resistance, which causes hyperinsulinemia, which in turn causes aberrant increased renal sodium reabsorption. The precise mechanisms underlying this greater salt sensitivity of hyperinsulinemic patients remain unclear. Abnormal activation of the recently identified with-no-lysine kinase (WNK)-oxidative stress-responsive kinase 1 (OSR1)/STE20/SPS1-related proline/alanine-rich kinase (SPAK)-NaCl cotransporter (NCC) phosphorylation cascade results in the salt-sensitive hypertension of pseudohypoaldosteronism type II. Here, we report a study of renal WNK-OSR1/SPAK-NCC cascade activation in the db/db mouse model of hyperinsulinemic metabolic syndrome. Thiazide sensitivity was increased, suggesting greater activity of NCC in db/db mice. In fact, increased phosphorylation of OSR1/SPAK and NCC was observed. In both Spak T243A/+ and OSR1 T185A/+ knock-in db/db mice, which carry mutations that disrupt the signal from WNK kinases, increased phosphorylation of NCC and elevated blood pressure were completely corrected, indicating that phosphorylation of SPAK and OSR1 by WNK kinases is required for the increased activation and phosphorylation of NCC in this model. Renal phosphorylated Akt was increased in db/db mice, suggesting that increased NCC phosphorylation is regulated by the phosphatidylinositol 3-kinase/Akt signaling cascade in the kidney in response to hyperinsulinemia. A phosphatidylinositol 3-kinase inhibitor (NVP-BEZ235) corrected the increased OSR1/SPAK-NCC phosphorylation. Another more specific phosphatidylinositol 3-kinase inhibitor (GDC-0941) and an Akt inhibitor (MK-2206) also inhibited increased NCC phosphorylation. These results indicate that the phosphatidylinositol 3-kinase/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in db/db mice. This mechanism may play a role in the pathogenesis of salt-sensitive hypertension in human hyperinsulinemic conditions, such as the metabolic syndrome.
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phosphatidylinositol 3 kinase akt signaling pathway activates the wnk OSR1 spak ncc phosphorylation cascade in hyperinsulinemic db db mice
Hypertension, 2012Co-Authors: Hidenori Nishida, Dario R Alessi, Motoko Chiga, Naohiro Nomura, Eisei Sohara, Tatemitsu Rai, Sei Sasaki, Shinichi UchidaAbstract:Metabolic syndrome patients have insulin resistance, which causes hyperinsulinemia, which in turn causes aberrant increased renal sodium reabsorption. The precise mechanisms underlying this greater salt sensitivity of hyperinsulinemic patients remain unclear. Abnormal activation of the recently identified with-no-lysine kinase (WNK)-oxidative stress-responsive kinase 1 (OSR1)/STE20/SPS1-related proline/alanine-rich kinase (SPAK)-NaCl cotransporter (NCC) phosphorylation cascade results in the salt-sensitive hypertension of pseudohypoaldosteronism type II. Here, we report a study of renal WNK-OSR1/SPAK-NCC cascade activation in the db/db mouse model of hyperinsulinemic metabolic syndrome. Thiazide sensitivity was increased, suggesting greater activity of NCC in db/db mice. In fact, increased phosphorylation of OSR1/SPAK and NCC was observed. In both SpakT243A/+ and OSR1T185A/+ knock-in db/db mice, which carry mutations that disrupt the signal from WNK kinases, increased phosphorylation of NCC and elevated blood pressure were completely corrected, indicating that phosphorylation of SPAK and OSR1 by WNK kinases is required for the increased activation and phosphorylation of NCC in this model. Renal phosphorylated Akt was increased in db/db mice, suggesting that increased NCC phosphorylation is regulated by the phosphatidylinositol 3-kinase/Akt signaling cascade in the kidney in response to hyperinsulinemia. A phosphatidylinositol 3-kinase inhibitor (NVP-BEZ235) corrected the increased OSR1/SPAK-NCC phosphorylation. Another more specific phosphatidylinositol 3-kinase inhibitor (GDC-0941) and an Akt inhibitor (MK-2206) also inhibited increased NCC phosphorylation. These results indicate that the phosphatidylinositol 3-kinase/Akt signaling pathway activates the WNK-OSR1/SPAK-NCC phosphorylation cascade in db/db mice. This mechanism may play a role in the pathogenesis of salt-sensitive hypertension in human hyperinsulinemic conditions, such as the metabolic syndrome.
