Abstract: SA-PO0500
Development of Direct Inhibitors of the Aquaporin-2 Water Channel
Session Information
- Fluid, Electrolyte, and Acid-Base Disorders: Basic Research
November 08, 2025 | Location: Exhibit Hall, 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
- Michizoe, Shotarou, Dokkyo Ika Daigaku, Shimotsuga District, Tochigi Prefecture, Japan
- Takahashi, Chisato, Dokkyo Ika Daigaku, Shimotsuga District, Tochigi Prefecture, Japan
- Kaiga, Akiko, Dokkyo Ika Daigaku, Shimotsuga District, Tochigi Prefecture, Japan
- Hishida, Erika, Dokkyo Ika Daigaku, Shimotsuga District, Tochigi Prefecture, Japan
- Sasaki, Sei, Tokyo Kagaku Daigaku, Meguro, Tokyo, Japan
- Rai, Tatemitsu, Dokkyo Ika Daigaku, Shimotsuga District, Tochigi Prefecture, Japan
Background
Aquaporin-2 (AQP2) water channel plays a pivotal role for maintaining water homeostasis. Direct AQP2 inhibition is expected to act as a selective “aquaretic” therapy—promoting free water excretion —offering a novel therapeutic strategy with fewer side effects for treatment of edematous disorders and SIADH. However, direct inhibitors of AQP2 with clinical application have not yet been developed.
Methods
This study focuses on developing direct AQP2 inhibitors by a novel high-throughput screening (HTS) approach :
1. Cell-based permeability assay using mpkCCD cells, which stably express AQP2. Water flux is measured across a 96-well permeable support under osmotic gradient, evaluating drug-induced inhibition of AQP2-mediated water transport.
2. Surface Plasmon Resonance (SPR) screening with AQP2 reconstituted into nanodiscs. This system allows for real-time binding analysis of over 20,000 small molecules in a detergent-free, native-like environment.
Results
1. In mpkCCDcl4 cells cultured in Transwells, 27.2±1.6% of fluid volume was transported from apical to basolateral side (mean±SD, n=80) in the presence of osmotic gradient.
2. AQP2 nanodisc construction and SPR binding setup have been successfully established. (Fig.1)
3. Among the 156 compounds applied for screening, 13 compounds exerted inhibitory effect on osmotic water flux by under -2SD of the negative control. (Fig.2)
Conclusion
A novel high-throughput screening system was established to evaluate water permeability of AQP2. Initial screening revealed several compounds with water permeability inhibitory effects, which may be promising candidates as direct AQP2 inhibitors.
Fig.1 Diagram and electron micrograph of the AQP2 nanodisc.
Fig.2 Volume of fluid passage from apical to basolateral side in mpkCCD cells following compound administration.
Funding
- Government Support – Non-U.S.