Dietary salt regulates the phosphorylation of OSR1/SPAK kinases and the sodium chloride cotransporter through aldosterone

WNK kinase is a serine/threonine kinase that plays an important role in electrolyte homeostasis. WNK4 significantly inhibits the surface expression of the sodium chloride co-transporter (NCC) by enhancing the degradation of NCC through a lysosomal pathway, but the mechanisms underlying this trafficking are unknown. Here, we investigated the effect of the lysosomal targeting receptor sortilin on NCC expression and degradation. In Cos-7 cells, we observed that the presence of WNK4 reduced the steady-state amount of NCC by approximately half. Co-transfection with truncated sortilin (a dominant negative mutant) prevented this WNK4-induced reduction in NCC. NCC immunoprecipitated with both wild-type sortilin and, to a lesser extent, truncated sortilin. Immunostaining revealed that WNK4 increased the co-localization of NCC with the lysosomal marker cathepsin D, and NCC co-localized with wild-type sortilin, truncated sortilin, and WNK4 in the perinuclear region. These findings suggest that WNK4 promotes NCC targeting to the lysosome for degradation via a mechanism involving sortilin.

Section: Discussionsupporting

confidence: 76%

Section: Discussionmentioning

confidence: 99%

WNK4 Enhances the Degradation of NCC through a Sortilin-Mediated Lysosomal Pathway

Zhou¹,

Zhuang

et al. 2010

“…Dysfunction of the NaCl cotransporter (NCC) in the DCT perturbs BP not only in the extreme phenotypes of patients with Gitelman's 1 and Gordon's 2 syndromes but also in healthy individuals, 3 and the inhibition of NCC by thiazide diuretics has a potent antihypertensive effect. 4 In the short term, NCC activity is regulated at the molecular level; neurohormonal inputs converge on intracellular signaling networks (WNK-SPAK/OSR1 5 and SGK1/Nedd4-2 pathways 6 ) that shuttle NCC to and from the plasma membrane 7 and induce posttranslational protein modifications that modify transport function (phosphorylation 8 and ubiquitylation 6 ). Sustained physiologic perturbations promote structural remodeling of DCTepithelium.…”

Section: Namentioning

confidence: 99%

Hypertrophy in the Distal Convoluted Tubule of an 11β-Hydroxysteroid Dehydrogenase Type 2 Knockout Model

Hunter

Ivy

Flatman

et al. 2015

Na+ transport in the renal distal convoluted tubule (DCT) by the thiazide-sensitive NaCl cotransporter (NCC) is a major determinant of total body Na + and BP. NCC-mediated transport is stimulated by aldosterone, the dominant regulator of chronic Na + homeostasis, but the mechanism is controversial. Transport may also be affected by epithelial remodeling, which occurs in the DCT in response to chronic perturbations in electrolyte homeostasis. Hsd11b2 2/2 mice, which lack the enzyme 11b-hydroxysteroid dehydrogenase type 2 (11bHSD2) and thus exhibit the syndrome of apparent mineralocorticoid excess, provided an ideal model in which to investigate the potential for DCT hypertrophy to contribute to Na + retention in a hypertensive condition. The DCTs of Hsd11b2 2/2 mice exhibited hypertrophy and hyperplasia and the kidneys expressed higher levels of total and phosphorylated NCC compared with those of wild-type mice. However, the striking structural and molecular phenotypes were not associated with an increase in the natriuretic effect of thiazide. In wild-type mice, Hsd11b2 mRNA was detected in some tubule segments expressing Slc12a3, but 11bHSD2 and NCC did not colocalize at the protein level. Thus, the phosphorylation status of NCC may not necessarily equate to its activity in vivo, and the structural remodeling of the DCT in the knockout mouse may not be a direct consequence of aberrant corticosteroid signaling in DCT cells. These observations suggest that the conventional concept of mineralocorticoid signaling in the DCT should be revised to recognize the complexity of NCC regulation by corticosteroids.

“…To date, we have identified several upstream regulators for WNK kinases, including hormonal factors, such as aldosterone, angiotensin II (AngII), insulin, and vasopressin. [7][8][9][10][11] However, the mechanisms of signal transduction from these factors to WNK kinases have not necessarily been clarified. We speculated that one of these regulations could be mediated by the ubiquitination of WNKs by KLHL2 and/or KLHL3.…”

mentioning

confidence: 99%

Kelch-Like Protein 2 Mediates Angiotensin II–With No Lysine 3 Signaling in the Regulation of Vascular Tonus

Zeniya

Morimoto

Takahashi

et al. 2015

Self Cite

Recently, the kelch-like protein 3 (KLHL3)-Cullin3 complex was identified as an E3 ubiquitin ligase for with no lysine (WNK) kinases, and the impaired ubiquitination of WNK4 causes pseudohypoaldosteronism type II (PHAII), a hereditary hypertensive disease. However, the involvement of WNK kinase regulation by ubiquitination in situations other than PHAII has not been identified. Previously, we identified the WNK3-STE20/SPS1-related proline/alanine-rich kinase-Na/K/Cl cotransporter isoform 1 phosphorylation cascade in vascular smooth muscle cells and found that it constitutes an important mechanism of vascular constriction by angiotensin II (AngII). In this study, we investigated the involvement of KLHL proteins in AngII-induced WNK3 activation of vascular smooth muscle cells. In the mouse aorta and mouse vascular smooth muscle (MOVAS) cells, KLHL3 was not expressed, but KLHL2, the closest homolog of KLHL3, was expressed. Salt depletion and acute infusion of AngII decreased KLHL2 and increased WNK3 levels in the mouse aorta. Notably, the AngII-induced changes in KLHL2 and WNK3 expression occurred within minutes in MOVAS cells. Results of KLHL2 overexpression and knockdown experiments in MOVAS cells confirmed that KLHL2 is the major regulator of WNK3 protein abundance. The AngII-induced decrease in KLHL2 was not caused by decreased transcription but increased autophagy-mediated degradation. Furthermore, knockdown of sequestosome 1/p62 prevented the decrease in KLHL2, suggesting that the mechanism of KLHL2 autophagy could be selective autophagy mediated by sequestosome 1/p62. Thus, we identified a novel component of signal transduction in AngII-induced vascular contraction that could be a promising drug target. 26: 212926: -213826: , 201526: . doi: 10.1681 Recently, the kelch-like protein 3 (KLHL3) and Cullin3 (Cul3) were identified as the genes responsible for a hereditary hypertensive diseasepseudohypoaldosteronism type II (PHAII). 1 Because the with no lysine (WNK) kinases (WNK1 and WNK4) had already been identified as the responsible genes for PHAII and the KLHL proteins were known to serve as substrate adaptors of Cul3-based E3 ubiquitin ligase, 1-3 we speculated and recently showed that KLHL3 functions as an E3 ligase with Cul3 for WNK4 and that the impaired ubiquitination of WNK4 and its subsequent increase within the cell stimulates the downstream OSR1/STE20/SPS1-related proline/alanine-rich kinase (SPAK)-NaCl cotransporter signaling and causes PHAII. 4 In addition to WNK4, WNK1 and other WNK kinases (WNK2 and WNK3) have been identified as substrates of KLHL3-Cul3 E3 ligase, because KLHL3 can bind to all WNKs in a highly conserved domain (acidic domain). 5 Furthermore, we recently reported that KLHL2 possesses a kelch repeat domain (WNK binding domain) highly similar to that of KLHL3 and that J Am Soc Nephrol