TY - JOUR
T1 - Multiple molecular mechanisms are involved in the activation of the kidney sodium-chloride cotransporter by hypokalemia
AU - Murillo-de-Ozores, Adrián R.
AU - Carbajal-Contreras, Héctor
AU - Magaña-Ávila, Germán R.
AU - Valdés, Raquel
AU - Grajeda-Medina, Leoneli I.
AU - Vázquez, Norma
AU - Zariñán, Teresa
AU - López-Saavedra, Alejandro
AU - Sharma, Avika
AU - Lin, Dao Hong
AU - Wang, Wen Hui
AU - Delpire, Eric
AU - Ellison, David H.
AU - Gamba, Gerardo
AU - Castañeda-Bueno, María
N1 - Publisher Copyright:
© 2022 International Society of Nephrology
PY - 2022/11
Y1 - 2022/11
N2 - Low potassium intake activates the kidney sodium-chloride cotransporter (NCC) whose phosphorylation and activity depend on the With-No-Lysine kinase 4 (WNK4) that is inhibited by chloride binding to its kinase domain. Low extracellular potassium activates NCC by decreasing intracellular chloride thereby promoting chloride dissociation from WNK4 where residue L319 of WNK4 participates in chloride coordination. Since the WNK4-L319F mutant is constitutively active and chloride-insensitive in vitro, we generated mice harboring this mutation that displayed slightly increased phosphorylated NCC and mild hyperkalemia when on a 129/sv genetic background. On a low potassium diet, upregulation of phosphorylated NCC was observed, suggesting that in addition to chloride sensing by WNK4, other mechanisms participate which may include modulation of WNK4 activity and degradation by phosphorylation of the RRxS motif in regulatory domains present in WNK4 and KLHL3, respectively. Increased levels of WNK4 and kidney-specific WNK1 and phospho-WNK4-RRxS were observed in wild-type and WNK4L319F/L319F mice on a low potassium diet. Decreased extracellular potassium promoted WNK4-RRxS phosphorylation in vitro and ex vivo as well. These effects might be secondary to intracellular chloride depletion, as reduction of intracellular chloride in HEK293 cells increased phospho-WNK4-RRxS. Phospho-WNK4-RRxS levels were increased in mice lacking the Kir5.1 potassium channel, which presumably have decreased distal convoluted tubule intracellular chloride. Similarly, phospho-KLHL3 was modulated by changes in intracellular chloride in HEK293 cells. Thus, our data suggest that multiple chloride-regulated mechanisms are responsible for NCC upregulation by low extracellular potassium.
AB - Low potassium intake activates the kidney sodium-chloride cotransporter (NCC) whose phosphorylation and activity depend on the With-No-Lysine kinase 4 (WNK4) that is inhibited by chloride binding to its kinase domain. Low extracellular potassium activates NCC by decreasing intracellular chloride thereby promoting chloride dissociation from WNK4 where residue L319 of WNK4 participates in chloride coordination. Since the WNK4-L319F mutant is constitutively active and chloride-insensitive in vitro, we generated mice harboring this mutation that displayed slightly increased phosphorylated NCC and mild hyperkalemia when on a 129/sv genetic background. On a low potassium diet, upregulation of phosphorylated NCC was observed, suggesting that in addition to chloride sensing by WNK4, other mechanisms participate which may include modulation of WNK4 activity and degradation by phosphorylation of the RRxS motif in regulatory domains present in WNK4 and KLHL3, respectively. Increased levels of WNK4 and kidney-specific WNK1 and phospho-WNK4-RRxS were observed in wild-type and WNK4L319F/L319F mice on a low potassium diet. Decreased extracellular potassium promoted WNK4-RRxS phosphorylation in vitro and ex vivo as well. These effects might be secondary to intracellular chloride depletion, as reduction of intracellular chloride in HEK293 cells increased phospho-WNK4-RRxS. Phospho-WNK4-RRxS levels were increased in mice lacking the Kir5.1 potassium channel, which presumably have decreased distal convoluted tubule intracellular chloride. Similarly, phospho-KLHL3 was modulated by changes in intracellular chloride in HEK293 cells. Thus, our data suggest that multiple chloride-regulated mechanisms are responsible for NCC upregulation by low extracellular potassium.
KW - Gitelman syndrome
KW - blood pressure
KW - distal convoluted tubule
KW - epithelial transport
KW - familial hyperkalemic hypertension
KW - potassium
UR - http://www.scopus.com/inward/record.url?scp=85138184479&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85138184479&partnerID=8YFLogxK
U2 - 10.1016/j.kint.2022.06.027
DO - 10.1016/j.kint.2022.06.027
M3 - Article
C2 - 35870644
AN - SCOPUS:85138184479
SN - 0085-2538
VL - 102
SP - 1030
EP - 1041
JO - Kidney International
JF - Kidney International
IS - 5
ER -