Hypertension is a major public health problem, affecting 1 billion people and contributing to death from heart attacks and strokes, the #1 and #3 causes of death in the US. We have used genetic and genomic approaches to identify genes and pathways that underlie this trait, and have identified renal salt handling as a principal determinant of human blood pressure. This work has unexpectedly identified new layers of physiologic regulation that are involeved in orchestrating the activities of diverse electrolyte flux pathways. These new mechanisms reveal that the kidney explicitly regulates the balance between renal salt reabsorption and K+ secretion via regulated activity of WNK kinases, whose level and activity is regulated by volume depletion. We have recently identified two new genes that play key roles in this pathway- these encode KLHL3 and CUL3, partners in an ubiquitin ligase complex. Mutation of either results in a similar phenotype to that resulting from WNK mutations. We have shown that this ubiquitin ligase targets WNKs for degradation and is regulated by phosphorylation. We are defining the biochemistry of this signaling pathway, its regulation by changes in volume and potassium homeostasis, and will produce new models that recapitulate the human disease, allowing further determination of the mechanisms by which this pathway imparts its effects. As part of this effort, we have made an unexpected discovery that has implications both for hypertension and also for the broader nuclear hormone receptor field. We have identified a novel phoshorylation site in the mineralocorticoid receptor (MR) that regulates the ability of MR to bind ligand. This site is exclusively phosphorylated in renal intercalated cells, and is modulated in opposite directions by volume depletion and hyperkalemia;dephosphorylation by AII signaling is WNK4-dependent and increases expression of electrolyte flux pathways in intercalated cells that increase electroneutral salt reabsorption. We will identify the kinase mediating this phosphorylation and elucidate the responsible signaling pathway. We are making a mouse model with inducible loss of phosphorylation in intercalated cells, which will reveal the role of this pathway in blood pressure and electrolyte homestasis.

Public Health Relevance

Hypertension is a major public health problem in the US and world-wide. Understanding its detailed pathogenesis provides the best opportunity for development of new strategies for prevention and treatment. The work herein is investigating previously unrecognized pathways involved in renal salt homeostasis, a major determinant of day to day blood pressure homeostasis in humans.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Program Projects (P01)
Project #
2P01DK017433-41A1
Application #
8742443
Study Section
Special Emphasis Panel (ZDK1-GRB-9 (M6))
Project Start
Project End
Budget Start
2014-09-18
Budget End
2015-06-30
Support Year
41
Fiscal Year
2014
Total Cost
$318,353
Indirect Cost
$127,150
Name
Yale University
Department
Type
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
Han, Jaeyong; Lee, Seung Hun; Giebisch, Gerhard et al. (2016) Potassium Channelopathies and Gastrointestinal Ulceration. Gut Liver 10:881-889
Stoops, Emily H; Hull, Michael; Caplan, Michael J (2016) Newly synthesized and recycling pools of the apical protein gp135 do not occupy the same compartments. Traffic 17:1272-1285
Ishizawa, Kenichi; Xu, Ning; Loffing, Johannes et al. (2016) Potassium depletion stimulates Na-Cl cotransporter via phosphorylation and inactivation of the ubiquitin ligase Kelch-like 3. Biochem Biophys Res Commun 480:745-751
Ferdaus, Mohammed Z; Barber, Karl W; López-Cayuqueo, Karen I et al. (2016) SPAK and OSR1 play essential roles in potassium homeostasis through actions on the distal convoluted tubule. J Physiol 594:4945-66
Scholl, Ute I; Stölting, Gabriel; Nelson-Williams, Carol et al. (2015) Recurrent gain of function mutation in calcium channel CACNA1H causes early-onset hypertension with primary aldosteronism. Elife 4:e06315
Chen, Tiane; Kocinsky, Hetal S; Cha, Boyoung et al. (2015) Cyclic GMP kinase II (cGKII) inhibits NHE3 by altering its trafficking and phosphorylating NHE3 at three required sites: identification of a multifunctional phosphorylation site. J Biol Chem 290:1952-65
Oza, Javin P; Aerni, Hans R; Pirman, Natasha L et al. (2015) Robust production of recombinant phosphoproteins using cell-free protein synthesis. Nat Commun 6:8168
Lin, Dao-Hong; Yue, Peng; Yarborough 3rd, Orlando et al. (2015) Src-family protein tyrosine kinase phosphorylates WNK4 and modulates its inhibitory effect on KCNJ1 (ROMK). Proc Natl Acad Sci U S A 112:4495-500
Pirman, Natasha L; Barber, Karl W; Aerni, Hans R et al. (2015) A flexible codon in genomically recoded Escherichia coli permits programmable protein phosphorylation. Nat Commun 6:8130
Farr, Glen A; Hull, Michael; Stoops, Emily H et al. (2015) Dual pulse-chase microscopy reveals early divergence in the biosynthetic trafficking of the Na,K-ATPase and E-cadherin. Mol Biol Cell 26:4401-11

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