Selective endocytosis controls slit diaphragm maintenance and dynamics in Drosophila nephrocytes
- University of Freiburg, Germany
- University of North Carolina at Chapel Hill, United States
Abstract
The kidneys generate about 180 liters of primary urine per day by filtration of plasma. An essential part of the filtration barrier is the slit diaphragm, a multiprotein complex containing nephrin as major component. Filter dysfunction typically manifests with proteinuria and mutations in endocytosis regulating genes were discovered as causes of proteinuria. However, it is unclear how endocytosis regulates the slit diaphragm and how the filtration barrier is maintained without either protein leakage or filter clogging. Here we study nephrin dynamics in podocyte-like nephrocytes of Drosophila and show that selective endocytosis either by dynamin- or flotillin-mediated pathways regulates a stable yet highly dynamic architecture. Short-term manipulation of endocytic functions indicates that dynamin-mediated endocytosis of ectopic nephrin restricts slit diaphragm formation spatially while flotillin-mediated turnover of nephrin within the slit diaphragm is needed to maintain filter permeability by shedding of molecules bound to nephrin in endosomes. Since slit diaphragms cannot be studied in vitro and are poorly accessible in mouse models, this is the first analysis of their dynamics within the slit diaphragm multiprotein complex. Identification of the mechanisms of slit diaphragm maintenance will help to develop novel therapies for proteinuric renal diseases that are frequently limited to symptomatic treatment.
Data availability
Transgenic Drosophila lines are available from the corresponding author upon reasonable request. Unprocessed image files were submitted to a public repository (zenodo.org, DOI: 10.5281/zenodo.6418762). Access is not restricted for scientific purposes.
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Author details
Funding
Deutsche Forschungsgemeinschaft (project-ID 431984000)
- Tobias Hermle
Deutsche Forschungsgemeinschaft (HE 7456/3-1)
- Tobias Hermle
Deutsche Forschungsgemeinschaft (HE 7456/4-1)
- Tobias Hermle
Deutsche Gesellschaft für Innere Medizin (Clinician Scientist Fellowship)
- Tobias Hermle
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2022, Lang et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Selective endocytosis controls slit diaphragm maintenance and dynamics in Drosophila nephrocytes
eLife 11:e79037.
https://doi.org/10.7554/eLife.79037
