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Dietary potassium stimulates Ppp1Ca-Ppp1r1a dephosphorylation of kidney NaCl co-transporter and reduces blood pressure

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  • Paul Richard Grimm, Johns Hopkins University
  • ,
  • Anamaria Tatomir, Johns Hopkins University
  • ,
  • Lena L Rosenbaek
  • Bo Young Kim, Johns Hopkins University
  • ,
  • Dimin Li, Johns Hopkins University
  • ,
  • Eric J Delpire, Vanderbilt University
  • ,
  • Robert A Fenton
  • Paul A Welling, Johns Hopkins University

Consumption of low dietary potassium, common with ultra-processed foods, activates the thiazide-sensitive sodium chloride cotransporter (NCC) via the WNK-SPAK kinase pathway to induce salt retention and elevate blood pressure (BP). However, it remains unclear how high potassium "DASH-like" diets inactivate the cotransporter and whether this decreases BP. A transcriptomic screen identified Ppp1C⍺, encoding PP1A, as a potassium up-regulated gene, and its negative regulator, Ppp1r1a, as a potassium-suppressed gene in the kidney. PP1A directly binds to and dephosphorylates NCC when extracellular potassium is elevated. Using mice genetically engineered to constitutively activate the NCC-regulatory kinase SPAK and thereby eliminate the effects of the WNK-SPAK kinase cascade, we confirmed that PP1A dephosphorylates NCC directly in a potassium-regulated manner. Prior adaptation to a high potassium diet was required to maximally dephosphorylate NCC and lower BP in the constitutively active SPAK mice, and this was associated with potassium-dependent suppression of Ppp1r1a, and dephosphorylation of its cognate protein, Inhibitory Subunit 1 (I1). In conclusion, potassium-dependent activation of PP1A and inhibition of I1 drives NCC dephosphorylation, providing a mechanism to explain how high dietary K+ lowers BP. Shifting signaling of PP1A in favor of activation of WNK-SPAK may provide an improved therapeutic approach for treating salt-sensitive hypertension.

TidsskriftJournal of Clinical Investigation
Antal sider17
StatusUdgivet - nov. 2023

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