Extracellular K(+) rapidly controls NaCl cotransporter phosphorylation in the native distal convoluted tubule by Cl(-) -dependent and independent mechanisms

TY - JOUR

T1 - Extracellular K(+) rapidly controls NaCl cotransporter phosphorylation in the native distal convoluted tubule by Cl(-) -dependent and independent mechanisms

AU - Czogalla, Jan

AU - Penton, David

AU - Wengi, Agnieszka

AU - Himmerkus, Nina

AU - Loffing-Cueni, Dominique

AU - Carrel, Monique

AU - Rajaram, Renuga Devi

AU - Staub, Olivier

AU - Bleich, Markus

AU - Schweda, Frank

AU - Loffing, Johannes

N1 - © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

PY - 2016/11/1

Y1 - 2016/11/1

N2 - KEY POINTS: High dietary potassium (K(+) ) intake dephosphorylates and inactivates the NaCl cotransporter (NCC) in the renal distal convoluted tubule (DCT). Using several ex vivo models, we show that physiological changes in extracellular K(+) , similar to those occurring after a K(+) rich diet, are sufficient to promote a very rapid dephosphorylation of NCC in native DCT cells. Although the increase of NCC phosphorylation upon decreased extracellular K(+) appears to depend on cellular Cl(-) fluxes, the rapid NCC dephosphorylation in response to increased extracellular K(+) is not Cl(-) -dependent. The Cl(-) -dependent pathway involves the SPAK/OSR1 kinases, whereas the Cl(-) independent pathway may include additional signalling cascades.ABSTRACT: A high dietary potassium (K(+) ) intake causes a rapid dephosphorylation, and hence inactivation, of the thiazide-sensitive NaCl cotransporter (NCC) in the renal distal convoluted tubule (DCT). Based on experiments in heterologous expression systems, it was proposed that changes in extracellular K(+) concentration ([K(+) ]ex ) modulate NCC phosphorylation via a Cl(-) -dependent modulation of the with no lysine (K) kinases (WNK)-STE20/SPS-1-44 related proline-alanine-rich protein kinase (SPAK)/oxidative stress-related kinase (OSR1) kinase pathway. We used the isolated perfused mouse kidney technique and ex vivo preparations of mouse kidney slices to test the physiological relevance of this model on native DCT. We demonstrate that NCC phosphorylation inversely correlates with [K(+) ]ex , with the most prominent effects occurring around physiological plasma [K(+) ]. Cellular Cl(-) conductances and the kinases SPAK/OSR1 are involved in the phosphorylation of NCC under low [K(+) ]ex . However, NCC dephosphorylation triggered by high [K(+) ]ex is neither blocked by removing extracellular Cl(-) , nor by the Cl(-) channel blocker 4,4'-diisothiocyano-2,2'-stilbenedisulphonic acid. The response to [K(+) ]ex on a low extracellular chloride concentration is also independent of significant changes in SPAK/OSR1 phosphorylation. Thus, in the native DCT, [K(+) ]ex directly and rapidly controls NCC phosphorylation by Cl(-) -dependent and independent pathways that involve the kinases SPAK/OSR1 and a yet unidentified additional signalling mechanism.

AB - KEY POINTS: High dietary potassium (K(+) ) intake dephosphorylates and inactivates the NaCl cotransporter (NCC) in the renal distal convoluted tubule (DCT). Using several ex vivo models, we show that physiological changes in extracellular K(+) , similar to those occurring after a K(+) rich diet, are sufficient to promote a very rapid dephosphorylation of NCC in native DCT cells. Although the increase of NCC phosphorylation upon decreased extracellular K(+) appears to depend on cellular Cl(-) fluxes, the rapid NCC dephosphorylation in response to increased extracellular K(+) is not Cl(-) -dependent. The Cl(-) -dependent pathway involves the SPAK/OSR1 kinases, whereas the Cl(-) independent pathway may include additional signalling cascades.ABSTRACT: A high dietary potassium (K(+) ) intake causes a rapid dephosphorylation, and hence inactivation, of the thiazide-sensitive NaCl cotransporter (NCC) in the renal distal convoluted tubule (DCT). Based on experiments in heterologous expression systems, it was proposed that changes in extracellular K(+) concentration ([K(+) ]ex ) modulate NCC phosphorylation via a Cl(-) -dependent modulation of the with no lysine (K) kinases (WNK)-STE20/SPS-1-44 related proline-alanine-rich protein kinase (SPAK)/oxidative stress-related kinase (OSR1) kinase pathway. We used the isolated perfused mouse kidney technique and ex vivo preparations of mouse kidney slices to test the physiological relevance of this model on native DCT. We demonstrate that NCC phosphorylation inversely correlates with [K(+) ]ex , with the most prominent effects occurring around physiological plasma [K(+) ]. Cellular Cl(-) conductances and the kinases SPAK/OSR1 are involved in the phosphorylation of NCC under low [K(+) ]ex . However, NCC dephosphorylation triggered by high [K(+) ]ex is neither blocked by removing extracellular Cl(-) , nor by the Cl(-) channel blocker 4,4'-diisothiocyano-2,2'-stilbenedisulphonic acid. The response to [K(+) ]ex on a low extracellular chloride concentration is also independent of significant changes in SPAK/OSR1 phosphorylation. Thus, in the native DCT, [K(+) ]ex directly and rapidly controls NCC phosphorylation by Cl(-) -dependent and independent pathways that involve the kinases SPAK/OSR1 and a yet unidentified additional signalling mechanism.

KW - Journal Article

U2 - 10.1113/JP272504

DO - 10.1113/JP272504

M3 - SCORING: Journal article

C2 - 27457700

VL - 594

SP - 6319

EP - 6331

JO - J PHYSIOL-LONDON

JF - J PHYSIOL-LONDON

SN - 0022-3751

IS - 21

ER -