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Abstract: FR-PO593

Generation and Analysis of Pseudohypoaldosteronism Type II Knockin Mice Caused by Nonsense Mutation in the Kelch Domain of KLHL3

Session Information

Category: Fluid and Electrolytes

  • 901 Fluid and Electrolytes: Basic

Authors

  • Lin, Chien-Ming, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
  • Yang, Sung-Sen, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
  • Lin, Shih-Hua P., Tri-Service General Hospital, Neihu, Taiwan
Background

Mutations in Kelch-like 3 (KLHL3) are the most common causative genes detected in patients with pseudohypoaldosteronism type II (PHAII). Although Klhl3R528H/+ knock-in (KI) mice carrying a missense mutation in kelch repeat domain has been reported, the nonsense KLHL3 mutation-causing PHAII in the same domain have not been fully investigated in vivo.

Methods

We generated and analyzed mutant Klhl3 KI mice harboring a nonsense W523X mutation in the kelch domain (corresponding to human KLHL3 W470X mutation). The associated protein expression of their kidney tissue was evaluated by western blot and immunofluorescence. The co-immunoprecipitation (co-IP) method was conducted to clarify the role of KLHL3 kelch repeat domain.

Results

Both heterozygous and homozygous Klhl3W523X/+ KI mice exhibited a significantly elevated systolic blood pressure (p < 0.05), secondary hyporeninemia (p < 0.05), a higher serum potassium level (K+) (p < 0.05) with decreased fractional excretion of K+ (FEK; p < 0.05) and a higher serum chloride level but lower bicarbonate level (p < 0.05). Their kidney tissues showed decreased levels of KLHL3 protein along with an enhanced downstream WNK1/4-SPAK/OSR1-N(K)CC phosphorylation. In vitro, co-IP demonstrated human KLHL3 harboring the PHAII-causing W470X mutation resulted in a decreased expression of total KLHL3 protein with truncated KLHL3 protein, leading to impaired binding affinity of KLHL3 to WNK1/4.

Conclusion

Klhl3W523X/+ KI mice feature typical PHAII with a simultaneous increase of WNK1 and WNK4 through impaired binding of the KLHL3 kelch domain to WNKs.