Crosstalk between phosphorylation and ubiquitination is involved in high salt-induced WNK4 expression

Area of Science:

• Biochemistry
• Molecular Biology
• Physiology

Background:

• With no lysine 4 (WNK4) is a kidney-expressed serine/threonine kinase implicated in salt-sensitive hypertension.
• The precise mechanisms by which dietary salt intake regulates WNK4 activity and abundance remain incompletely understood.

Purpose of the Study:

• To investigate the impact of high salt conditions on WNK4 protein expression, ubiquitination, and phosphorylation.
• To elucidate the molecular interplay between WNK4 phosphorylation and ubiquitination under high salt exposure.

Main Methods:

• Western blotting was employed to quantify WNK4 protein levels in C57BL/6 mice and HEK293 cells subjected to high salt treatment.
• Co-immunoprecipitation assays were utilized to assess WNK4 ubiquitination levels.
• Specific ubiquitination (Lys-1023) and phosphorylation (Ser-1022) sites on WNK4 were identified.

Main Results:

• High salt significantly upregulated WNK4 protein expression in both mice and cell models.
• WNK4 ubiquitination was markedly decreased under high salt conditions.
• Phosphorylation at Ser-1022 was identified as a prerequisite for WNK4 ubiquitination at Lys-1023.

Conclusions:

• High salt intake downregulates WNK4 phosphorylation, subsequently reducing its ubiquitination and subsequent degradation.
• This leads to an accumulation of WNK4 protein, potentially contributing to the pathogenesis of salt-sensitive hypertension.
• Evidence of crosstalk between WNK4 phosphorylation and ubiquitination pathways was demonstrated.