Phenotypes of pseudohypoaldosteronism type II caused by the WNK4 D561A missense mutation are dependent on the WNK-OSR1/SPAK kinase cascade.

Abstract

We recently reported increased phosphorylation of the NaCl cotransporter (NCC) in Wnk4(D561A/+) knock-in mice, an ideal model of the human hereditary hypertensive disease pseudohypoaldosteronism type II (PHAII). Although previous in vitro studies had suggested the existence of a phosphorylation cascade involving the WNK, OSR1 and SPAK kinases, whether the WNK-OSR1/SPAK cascade is in fact fully responsible for NCC phosphorylation in vivo and whether the activation of this cascade is the sole mediator of PHAII remained to be determined. To clarify these issues, we mated the Wnk4(D561A/+) knock-in mice with Spak and Osr1 knock-in mice in which the T-loop threonine residues in SPAK and OSR1 (243 and 185, respectively) were mutated to alanine to prevent activation by WNK kinases. We found that NCC phosphorylation was almost completely abolished in Wnk4(D561A/+)Spak(T)(243A/T243A)Osr1(T185A/+) triple knock-in mice, clearly demonstrating that NCC phosphorylation in vivo is dependent on the WNK-OSR1/SPAK cascade. In addition, the high blood pressure, hyperkalemia and metabolic acidosis observed in Wnk4(D561A/+) mice were corrected in the triple knock-in mice. These results clearly establish that PHAII caused by the WNK4 D561A mutation is dependent on the activation of the WNK-OSR1/SPAK-NCC cascade and that the contribution of other mechanisms to PHAII (independent of the WNK-OSR1/SPAK cascade) could be minimal.

• Authors: Motoko Chiga, Fatema H Rafiqi, Dario R Alessi, Eisei Sohara, Akihito Ohta, Tatemitsu Rai, Sei Sasaki, Shinichi Uchida
• Journal: Journal of cell science (J Cell Sci) Vol. 124 Issue Pt 9 Pg. 1391-5 (May 01 2011) ISSN: 1477-9137 [Electronic] England
• PMID: 21486947 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Prkwnk4 protein, mouse
• Stk39 protein, mouse
• OXSR1 protein, mouse
• Protein Serine-Threonine Kinases

Topics

• Animals
• Blood Pressure (genetics, physiology)
• Immunoblotting
• Mice
• Mutation, Missense (genetics)
• Protein Serine-Threonine Kinases (genetics, metabolism)
• Pseudohypoaldosteronism (genetics, metabolism, physiopathology)