Osmotic stress induces the phosphorylation of WNK4 Ser575 via the p38MAPK-MK pathway

Abstract

The With No lysine [K] (WNK)-Ste20-related proline/alanine-rich kinase (SPAK)/oxidative stress-responsive kinase 1 (OSR1) pathway has been reported to be a crucial signaling pathway for triggering pseudohypoaldosteronism type II (PHAII), an autosomal dominant hereditary disease that is characterized by hypertension. However, the molecular mechanism(s) by which the WNK-SPAK/OSR1 pathway is regulated remain unclear. In this report, we identified WNK4 as an interacting partner of a recently identified MAP3K, apoptosis signal-regulating kinase 3 (ASK3). We found that WNK4 is phosphorylated in an ASK3 kinase activity-dependent manner. By exploring the ASK3-dependent phosphorylation sites, we identified Ser575 as a novel phosphorylation site in WNK4 by LC-MS/MS analysis. ASK3-dependent WNK4 Ser575 phosphorylation was mediated by the p38MAPK-MAPK-activated protein kinase (MK) pathway. Osmotic stress, as well as hypotonic low-chloride stimulation, increased WNK4 Ser575 phosphorylation via the p38MAPK-MK pathway. ASK3 was required for the p38MAPK activation induced by hypotonic stimulation but was not required for that induced by hypertonic stimulation or hypotonic low-chloride stimulation. Our results suggest that the p38MAPK-MK pathway might regulate WNK4 in an osmotic stress-dependent manner but its upstream regulators might be divergent depending on the types of osmotic stimuli.

Extracellular K+ rapidly controls NaCl cotransporter phosphorylation in the native distal convoluted tubule by Cl−‐dependent and independent mechanisms

“…) and recent data suggest that WNK4 is phosphorylated in response to osmotic stress (Maruyama et al . ).…”

“…Other mechanisms, such as changes in cell volume, remain to be considered. Indeed, hypo-osmotic cell swelling stimulates SPAK-dependent NCC activation (Richardson et al 2008) and recent data suggest that WNK4 is phosphorylated in response to osmotic stress (Maruyama et al 2016).…”

A PP6-ASK3 Module Coordinates the Bidirectional Cell Volume Regulation under Osmotic Stress

“…In some cell lines, p38 MAPK is important for both RVD and RVI (Bildin et al, 2003;Chiri et al, 2004;vom Dahl et al, 2001). MEKK3, a MAP3K, is responsible for p38 MAPK activation under hyperosmotic stress (Uhlik et al, 2003), while ASK3 is a counterpart under hypoosmotic stress (Maruyama et al, 2016). Thus, p38 MAPK is a candidate downstream target of ASK3 in RVD.…”

The Molecular Genetics of Gordon Syndrome

“…WNK4 has been shown to be regulated by various other molecules that clearly influence WNK signalling. Osmotic stress and hypotonic low-chloride stimulation increase WNK4 Ser575 phosphorylation via the p38MAPK-MK pathway, suggesting that this pathway might regulate WNK4 in an osmotic stress-dependent manner [64]. Other molecules that have been shown to stimulate elements of the WNK-SPAK pathway include aldosterone, angiotensin II, vasopressin, norepinephrine, insulin, and parathyroid hormone.…”