Abstract: TH-OR86
A Drosophila Model for Dent Disease
Session Information
- Non-Cystic Genetic Kidney Diseases: Disease Genes, Modifiers, and Therapies
October 24, 2024 | Location: Room 23, Convention Center
Abstract Time: 05:10 PM - 05:20 PM
Category: Genetic Diseases of the Kidneys
- 1202 Genetic Diseases of the Kidneys: Non-Cystic
Authors
- Simons, Matias, University Hospital Heidelberg, Institute of Human Genetics, Heidelberg, Germany
- Devuyst, Olivier, Universitat Zurich, Zurich, Zurich, Switzerland
- Dibra, Indira, University Hospital Heidelberg, Institute of Human Genetics, Heidelberg, Germany
- Christer, Salómon, University Hospital Heidelberg, Institute of Human Genetics, Heidelberg, Germany
Background
Dent’s disease is an inherited disease characterized by the loss of protein uptake receptors cubilin and megalin and subsequent impairment of the endocytic pathway in the proximal tubule of the kidney. The predominant cause for Dent’s disease is mutations in the human CLCN5 gene, encoding the kidney-specific chloride-proton exchanger ClC-5. Utilizing a Drosophila model for Dent’s disease, we sought to uncover the pathogenic mechanisms behind the protein uptake receptor loss.
Methods
The functional orthologue of ClC-5, ClC-c, was knocked down in Drosophila Nephrocytes through UAS-GAL4 based-expression of specific RNAi constructs. The effects of knockdown of ClC-c and other genes were measured using immunofluorescence (IF) analysis or by co-expression with fluorescent reporters. Endocytic function was measured through uptake of FITC-albumin. IF analysis was additionally performed on kidney sections from age matched control and Clcn5 knockout mice.
Results
Utillizing ClC-c-deficient Drosophila nephrocytes we were able to recapitulate the loss of surface cubilin and decreased endocytic activity phenotypes that are characteristic of Dent’s disease. Cubilin was found to localize to the endoplasmic reticulum (ER) and, faintly, to degradative compartments. A similar ER retention of cubilin could be produced upon loss of Rab11. Dent’s disease nephrocytes also displayed large autolysosomal compartments with strong cholesterol storage. Knockdown of dynamin and cubilin mimicked these phenotypes, suggesting they occur downstream of impaired endocytosis. Additionally, cortical actin accumulation and mislocalization of slit diaphragms could be observed at the cortex of ClC-c knockdown nephrocytes, in line with previously published glomerular defects in Dent’s disease patients. Finally, ER retention, lysosomal cholesterol storage and actin accumulation could be reproduced in a mouse model for Dent's disease.
Conclusion
We have found that cubilin is retained in the ER which seems to occur through perturbed function of the endosomal recycling pathway. The impaired endocytosis in turn leads to reduced protein uptake, which is possibly linked to the enhanced autophagy. Our study has uncovered a broad range of evolutionarily conserved phenotypes associated with Dent’s disease which may pave the way for new therapeutic strategies in Dent’s disease.
Funding
- Government Support – Non-U.S.