Kidney Week

Abstract: TH-PO0036

Role of NEDD8-Activating Enzyme E1 in CUL3Δ9-Associated Signaling in Familial Hyperkalemic Hypertension

Session Information

• Fluid, Electrolyte, and Acid-Base Disorders: Basic Research
  October 22, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Fluid, Electrolytes, and Acid-Base Disorders

• 1101 Fluid, Electrolyte, and Acid-Base Disorders: Basic

Authors

• Miyasako, Kisho, Oregon Health & Science University, Portland, Oregon, United States

Kisho Miyasako, MD, PhD

• Thaitongsuk, Poomipat, Oregon Health & Science University, Portland, Oregon, United States

Poomipat Thaitongsuk

• Morrow, Ashley M., Oregon Health & Science University, Portland, Oregon, United States

Ashley M. Morrow, MS

• Cornelius, Ryan J., Oregon Health & Science University, Portland, Oregon, United States

Ryan J. Cornelius, PhD

• McCormick, James A., Oregon Health & Science University, Portland, Oregon, United States

James A. McCormick, PhD

Background

The Cullin 3 (CUL3) E3 ubiquitin ligase complex regulates kidney electrolyte homeostasis by promoting ubiquitination and degradation of With-No-Lysine 4 (WNK4), thereby controlling Na⁺-Cl^- cotransporter (NCC) activity in the distal nephron. A CUL3 mutant lacking exon 9 (CUL3Δ9) causes WNK4 accumulation and subsequent NCC hyperactivation, leading to Familial Hyperkalemic hypertension (FHHt). The wild type CUL3-RING ligase complex is regulated by covalent conjugation (activates the CUL3 complex) and then removal (inhibits the CUL3 complex) of the ubiquitin-like protein NEDD8. This cycling is critical for normal CUL3 activity. In FHHt, the ubiquitin ligase is dysfunctional due to impaired NEDD8 removal from CUL3Δ9. We evaluated the effects of disrupting NEDD8-activating enzyme E1 (NAE1), a critical enzyme for mediating linkage of NEDD8 to CUL3, on WNK4-meidated activation of NCC, and whether preventing conjugation of NEDD8 to CUL3Δ9 mitigates the FHHt phenotype.

Methods

We generated doxycycline-inducible kidney tubule-specific, NAE1 knockout mice using the Pax8-Cre system (TS-NAE1 KO). We also crossed these mice with CUL3^flox/WT/ CUL3^Δ9+ Pax8-Cre mice, which display an FHHt phenotype, to evaluate the effects of NAE1 deletion on CUL3Δ9-mediated FHHt (CUL3^+/-/Δ9/NAE1-HET mice, with CUL3^+/-/NAE1-HET mice as controls). We performed physiological and molecular biological analyses to assess changes in electrolyte metabolism and signaling pathways.

Results

TS-NAE1 KO knockout mice showed higher phosphorylated NCC (pNCC) expression after 4 days of doxycycline induction, with higher expression of CUL3, WNK4, phosphorylated SPAK (downstream of WNK4), and pNCC after 4 weeks of induction. CUL3^+/-/Δ9/NAE1-HET mice did not exhibit hyperkalemia or enhanced NCC activation, the primary characteristics of FHHt, when compared to control mice.

Conclusion

TS-NAE1 KO mice displayed activation of the WNK4–SPAK–NCC signaling pathway, consistent with impaired activation of the CUL3 ubiquitin ligase complex. Heterozygous NAE1 deficiency in the CUL3Δ9 genetic context did not result in the major features of FHHt, including hyperkalemia and NCC activation, compared to control mice. These findings suggest that excessive neddylation is a critical component of the pathogenesis of FHHt caused by the CUL3Δ9 mutation.

Funding

• NIDDK Support