Search

Gain-of-function mutations in with no lysine (K)1 (WNK1) and WNK4genes are responsible for familial hyperkalemic hypertension (FHHt), a rare, inherited disorder characterized by arterial hypertension and hyperkalemia with metabolic acidosis. More recently, FHHt-causing mutations in the Kelch-like 3-Cullin 3 (KLHL3-CUL3) E3 ubiquitin ligase complex have shed light on the importance of WNK's cellular degradation on renal ion transport. Using full exome sequencing for a 4-generation family and then targeted sequencing in other suspected cases, we have identified new missense variants in the WNK1 gene clustering in the short conserved acidic motif known to interact with the KLHL3-CUL3 ubiquitin complex. Affected subjects had an early onset of a hyperkalemic hyperchloremic phenotype, but normal blood pressure values' Functional experiments in Xenopus laevis oocytes and HEK293T cells demonstrated that these mutations strongly decrease the ubiquitination of the kidney-specific isoform KS-WNK1 by the KLHL3-CUL3 complex rather than the long ubiquitous catalytically active L-WNK1 isoform. A corresponding CRISPR/Cas9 engineered mouse model recapitulated both the clinical and biological phenotypes. Renal investigations showed increased activation of the Ste20 proline alanine-rich kinase-[Na.sup.+]-[Cl.sup.-] cotransporter (SPAK-NCC) phosphorylation cascade, associated with impaired ROMK apical expression in the distal part of the renal tubule. Together, these new WNK1 genetic variants highlight the importance of the KS-WNK1 isoform abundance on potassium homeostasis., Introduction Familial hyperkalemic hypertension (FHHt), also known as Gordon syndrome and pseudohypoaldosteronism type 2, is a rare disease associated with net positive [Na.sup.+] balance and renal [K.sup.+] retention resulting in [...]

Unique situations in female physiology require volume retention. Accordingly, a dimorphic regulation of the thiazide-sensitive Na+-Cl- cotransporter (NCC) has been reported, with a higher activity in females than in males. However, little is known about the hormones and mechanisms involved. Here, we present evidence that estrogens, progesterone, and prolactin stimulate NCC expression and phosphorylation. The sex difference in NCC abundance, however, is species dependent. In rats, NCC phosphorylation is higher in females than in males, while in mice both NCC expression and phosphorylation is higher in females, and this is associated with increased expression and phosphorylation of full-length STE-20 proline-alanine-rich kinase (SPAK). Higher expression/phosphorylation of NCC was corroborated in humans by urinary exosome analysis. Ovariectomy in rats resulted in decreased expression and phosphorylation of the cotransporter and promoted the shift of SPAK isoforms toward the short inhibitory variant SPAK2. Conversely, estradiol or progesterone administration to ovariectomized rats restored NCC phosphorylation levels and shifted SPAK expression and phosphorylation towards the full-length isoform. Estradiol administration to male rats induced a significant increase in NCC phosphorylation. NCC is also modulated by prolactin. Administration of this peptide hormone to male rats induced increased phosphorylation of NCC, an effect that was observed even using the ex vivo kidney perfusion strategy. Our results indicate that estradiol, progesterone, and prolactin, the hormones that are involved in sexual cycle, pregnancy and lactation, upregulate the activity of NCC. [ABSTRACT FROM AUTHOR]