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Mutig K, Wang MX, Zhang DD, Lin DH, Ellison DH, Thomson MN, Bachmann S, Wang WH. Kir4.1 is Critical for Regulation of ENaC and ROMK Activity in the Late Distal Nephron. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.05477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Thomson MN, Cuevas CA, Bewarder TM, Dittmayer C, Miller LN, Si J, Cornelius RJ, Su XT, Yang CL, McCormick JA, Hadchouel J, Ellison DH, Bachmann S, Mutig K. WNK bodies cluster WNK4 and SPAK/OSR1 to promote NCC activation in hypokalemia. Am J Physiol Renal Physiol 2019; 318:F216-F228. [PMID: 31736353 DOI: 10.1152/ajprenal.00232.2019] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
K+ deficiency stimulates renal salt reuptake via the Na+-Cl- cotransporter (NCC) of the distal convoluted tubule (DCT), thereby reducing K+ losses in downstream nephron segments while increasing NaCl retention and blood pressure. NCC activation is mediated by a kinase cascade involving with no lysine (WNK) kinases upstream of Ste20-related proline-alanine-rich kinase (SPAK) and oxidative stress-responsive kinase-1 (OSR1). In K+ deficiency, WNKs and SPAK/OSR1 concentrate in spherical cytoplasmic domains in the DCT termed "WNK bodies," the significance of which is undetermined. By feeding diets of varying salt and K+ content to mice and using genetically engineered mouse lines, we aimed to clarify whether WNK bodies contribute to WNK-SPAK/OSR1-NCC signaling. Phosphorylated SPAK/OSR1 was present both at the apical membrane and in WNK bodies within 12 h of dietary K+ deprivation, and it was promptly suppressed by K+ loading. In WNK4-deficient mice, however, larger WNK bodies formed, containing unphosphorylated WNK1, SPAK, and OSR1. This suggests that WNK4 is the primary active WNK isoform in WNK bodies and catalyzes SPAK/OSR1 phosphorylation therein. We further examined mice carrying a kidney-specific deletion of the basolateral K+ channel-forming protein Kir4.1, which is required for the DCT to sense plasma K+ concentration. These mice displayed remnant mosaic expression of Kir4.1 in the DCT, and upon K+ deprivation, WNK bodies developed only in Kir4.1-expressing cells. We postulate a model of DCT function in which NCC activity is modulated by plasma K+ concentration via WNK4-SPAK/OSR1 interactions within WNK bodies.
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Affiliation(s)
- Martin N Thomson
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Catherina A Cuevas
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Tim M Bewarder
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Carsten Dittmayer
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Lauren N Miller
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Jinge Si
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Xiao-Tong Su
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon.,Renal Section, Veterans Affairs Portland Health Care System, Portland, Oregon
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Juliette Hadchouel
- Institut National de la Santé et de la Recherche Médicale, Paris Cardiovascular Research Center, Paris, France
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon.,Renal Section, Veterans Affairs Portland Health Care System, Portland, Oregon
| | - Sebastian Bachmann
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Kerim Mutig
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany.,I.M. Sechenov First Moscow State Medical University of the Ministry of Healthcare of the Russian Federation (Sechenovskiy University), Moscow, Russia
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Thomson MN, Horn J, Mutig K, Bachmann S. Short‐ and Long‐Term Furosemide Treatment Triggers WNK Body Formation in the Rat Distal Nephron. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.862.14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - John Horn
- AnatomyCharité – Universitätsmedizin BerlinBerlinGermany
| | - Kerim Mutig
- AnatomyCharité – Universitätsmedizin BerlinBerlinGermany
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Thomson MN, Schneider W, Kettritz R, Mutig K, Ellison DH, Bachmann S. WNK Bodies Develop in the Distal Convoluted Tubule of the Human Kidney in Chronic Hypokalemia. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.862.13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Ralph Kettritz
- Nephrology and Intensive Care MedicineCharité – Universitätsmedizin BerlinBerlinGermany
- Experimental and Clinical Research CenterA joint cooperation between the Charité − Universitätsmedizin Berlin and the Max Delbrück Center for Molecular MedicineBerlinGermany
| | - Kerim Mutig
- AnatomyCharité – Universitätsmedizin BerlinBerlinGermany
| | - David H. Ellison
- Division of Nephrology & Hypertension, Department of MedicineOregon Health & Science UniversityPortlandOR
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Thomson MN, Schneider W, Mutig K, Ellison DH, Kettritz R, Bachmann S. Patients with hypokalemia develop WNK bodies in the distal convoluted tubule of the kidney. Am J Physiol Renal Physiol 2018; 316:F292-F300. [PMID: 30484345 DOI: 10.1152/ajprenal.00464.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Hypokalemia contributes to the progression of chronic kidney disease, although a definitive pathophysiological theory to explain this remains to be established. K+ deficiency results in profound alterations in renal epithelial transport. These include an increase in salt reabsorption via the Na+-Cl- cotransporter (NCC) of the distal convoluted tubule (DCT), which minimizes electroneutral K+ loss in downstream nephron segments. In experimental conditions of dietary K+ depletion, punctate structures in the DCT containing crucial NCC-regulating kinases have been discovered in the murine DCT and termed "WNK bodies," referring to their component, with no K (lysine) kinases (WNKs). We hypothesized that in humans, WNK bodies occur in hypokalemia as well. Renal needle biopsies of patients with chronic hypokalemic nephropathy and appropriate controls were examined by histological stains and immunofluorescence. Segment- and organelle-specific marker proteins were used to characterize the intrarenal and subcellular distribution of established WNK body constituents, namely, WNKs and Ste20-related proline-alanine-rich kinase (SPAK). In both patients with hypokalemia, WNKs and SPAK concentrated in non-membrane-bound cytoplasmic regions in the DCT, consistent with prior descriptions of WNK bodies. The putative WNK bodies were located in the perinuclear region close to, but not within, the endoplasmic reticulum. They were closely adjacent to microtubules but not clustered in aggresomes. Notably, we provide the first report of WNK bodies, which are functionally challenging structures associated with K+ deficiency, in human patients.
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Affiliation(s)
- Martin N Thomson
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin , Germany
| | - Wolfgang Schneider
- Department of Pathology, Charité-Universitätsmedizin Berlin, Berlin , Germany
| | - Kerim Mutig
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin , Germany
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Ralph Kettritz
- Nephrology and Medical Intensive Care Medicine, Charité-Universitätsmedizin Berlin, Berlin , Germany.,Experimental and Clinical Research Center, Charité-Universitätsmedizin Berlin and Max Delbrück Center for Molecular Medicine , Berlin , Germany
| | - Sebastian Bachmann
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin , Germany
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