Abstract: FR-PO932
Discovery of a Small Molecule with an Inhibitory Role for RAB11 with Validation in Nephrocytes
Session Information
- Glomerular Diseases: Potpourri
October 25, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Lempicki, Camille, Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
- Milosavljevic, Julian, Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
- Laggner, Christian, Atomwise Inc, San Francisco, California, United States
- Lang, Konrad, Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
- Hermle, Tobias F., Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
Background
DNA variants in TBC1D8B have been discovered as a monogenic cause of nephrotic syndrome. TBC1D8B dysfunction has been linked to disinhibition of RAB11. No specific small molecule inhibitor for RAB11 has been described so far but might offer potential therapeutic value.
Methods
To identify candidate compounds, the proprietary AtomNet platform was utilized for deep learning-based computational screening. For experimental confirmation, we employed an in vitro platform reflecting RAB11 activity through the exocytosis of GFP. We further examined autophagy, which independently relies on RAB11. Toxicity was assessed by Annexin V/propidium iodide exposure and flow cytometry in cultured podocytes. Toxicity in vivo was studied by exposure of Drosophila larvae. In podocyte-like Drosophila nephrocytes, we further explored the impact of feeding the compound on subcellular localization of endogenous Rab11 and endocytic nephrocyte function.
Results
From 94 candidate molecules identified in silico, we confirmed nine compounds through a decrease of secretory GFP in the cellular supernatant, which suggests efficient inhibition of RAB11. We then validated three compounds by measuring a decrease in autophagic flux suggesting inhibition on another cellular function dependent on RAB11. All three inhibitors showed druglike properties. Flow cytometry after Annexin V/propidium iodide exposure indicated absence of toxicity for these chemicals. The survival rate of Drosophila larvae fed with the inhibitors was unaffected compared to the control, similarly suggesting low toxicity in vivo. Drosophila larvae exposed to compound with highest oral bioavailability showed subcellular dispersal of endogenous Rab11 and a decrease in RAB11-dependent nephrocyte function.
Conclusion
We identified three small molecules exhibiting inhibitory function for Rab11. This discovery may open avenues for treating RAB11-associated nephrotic syndrome and other RAB11-associated disorders.
Funding
- Commercial Support – Atomwise Inc.