title: Potassium depletion stimulates Na-Cl cotransporterviaphosphorylation and inactivation of the ubiquitin ligase Kelch-like 3.
abstract: Kelch-like 3 (KLHL3) is a component of an E3 ubiquitin ligase complex that regulates blood pressure by targeting With-No-Lysine (WNK) kinases for degradation. Mutations in KLHL3 cause constitutively increased renal salt reabsorption and impaired K+secretion, resulting in hypertension and hyperkalemia. Although clinical studies have shown that dietary K+intake affects blood pressure, the mechanisms have been obscure. In this study, we demonstrate that the KLHL3 ubiquitin ligase complex is involved in the low-K+-mediated activation of Na-Cl cotransporter (NCC) in the kidney. In the distal convoluted tubules of mice eating a low-K+diet, we found increased KLHL3 phosphorylation at S433 (KLHL3S433-P), a modification that impairs WNK binding, and also reduced total KLHL3 levels. These changes are accompanied by the accumulation of the target substrate WNK4, and activation of the downstream kinases SPAK (STE20/SPS1-related proline-alanine-rich protein kinase) and OSR1 (oxidative stress-responsive 1), resulting in NCC phosphorylation and its accumulation at the plasma membrane. Increased phosphorylation of S433 was explained by increased levels of active, phosphorylated protein kinase C (but not protein kinase A), which directly phosphorylates S433. Moreover, in HEK cells expressing KLHL3 and WNK4, we showed that the activation of protein kinase C by phorbol 12-myristate 13-acetate induces KLHL3S433-Pand increases WNK4 levels by abrogating its ubiquitination. These data demonstrate the role of KLHL3 in low-K+-mediated induction of NCC; this physiologic adaptation reduces distal electrogenic Na+reabsorption, preventing further renal K+loss but promoting increased blood pressure.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ishizawa
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan; Department of Nephrology, Tianjin First Central Hospital, Tianjin, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Xu
authors.affiliation: Institute of Anatomy, University of Zurich, Zurich, Switzerland.
authors.forename: Johannes
authors.initials: J
authors.lastname: Loffing
authors.affiliation: Department of Genetics, Yale University School of Medicine, Connecticut, U.S.A.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Lifton
authors.affiliation: Division of Clinical Epigenetics, Research center for Advanced Science and Technology, The University of Tokyo, Japan.
authors.forename: Toshiro
authors.initials: T
authors.lastname: Fujita
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Shunya
authors.initials: S
authors.lastname: Uchida
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan; Division of Clinical Epigenetics, Research center for Advanced Science and Technology, The University of Tokyo, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Shibata
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D004032:Diet; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D006973:Hypertension / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D007008:Hypokalemia / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008840:Microfilament Proteins / Q000235:genetics* / Q000378:metabolism; D015778:Minor Histocompatibility Antigens / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011191:Potassium Deficiency / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D017419:Potassium, Dietary / Q000008:administration & dosage / Q000378:metabolism*; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D012964:Sodium / Q000378:metabolism; D064486:Solute Carrier Family 12, Member 3 / Q000235:genetics / Q000378:metabolism; D000076204:WNK Lysine-Deficient Protein Kinase 1
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C000598025:KLHL3 protein, mouse; D008840:Microfilament Proteins; D015778:Minor Histocompatibility Antigens; D017419:Potassium, Dietary; C578875:Slc12a3 protein, mouse; D064486:Solute Carrier Family 12, Member 3; D012964:Sodium; C499024:Prkwnk4 protein, mouse; C486407:Stk39 protein, mouse; C534421:OXSR1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D000076204:WNK Lysine-Deficient Protein Kinase 1; C498744:Wnk1 protein, mouse; D011493:Protein Kinase C
keywords: distal nephron; hypokalemia; post-translational modification; ubiquitin proteasome pathway