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Updated: Nov 19, 2025

Analysis of Endocytic Uptake and Retrograde Transport to the Trans-Golgi Network Using Functionalized Nanobodies in Cultured Cells
Published on: February 21, 2019
Mammalian VPS45 orchestrates trafficking through the endosomal system
Laura Frey1, Natalia Ziętara1, Marcin Łyszkiewicz1
1Department of Pediatrics, Dr von Hauner Children's Hospital, Ludwig-Maximilians-Universität München, Munich, Germany.
Vacuolar protein sorting 45 homolog (VPS45) is crucial for endosomal trafficking and receptor recycling. Its absence disrupts cellular organization, leading to developmental defects and impaired immune cell function.
Area of Science:
- Cell Biology
- Molecular Biology
- Developmental Biology
Background:
- Vacuolar protein sorting 45 homolog (VPS45) is a Sec1/Munc18 (SM) family member involved in endosomal trafficking.
- VPS45 deficiency in humans causes congenital neutropenia, bone marrow fibrosis, and extramedullary hematopoiesis.
Purpose of the Study:
- To elucidate the detailed mechanisms of mammalian VPS45 function in intracellular trafficking.
- To investigate the role of VPS45 in maintaining endolysosomal organization and receptor recycling.
Main Methods:
- Investigated VPS45 function in mammalian cells and mouse models.
- Analyzed endosomal trafficking pathways, including Rab5-to-Rab7 conversion.
- Examined the trafficking of granulocyte colony-stimulating factor receptor.
Main Results:
- Loss of VPS45 disrupts intracellular organization of endolysosomal vesicles and cell-surface receptor recycling.
- VPS45 deficiency impairs Rab5-to-Rab7 conversion, trapping cargo in early endosomes and hindering lysosomal delivery.
- Aberrant trafficking of the granulocyte colony-stimulating factor receptor was observed in VPS45-deficient cells.
- VPS45 deficiency in mice is incompatible with embryonic development.
Conclusions:
- Mammalian VPS45 is essential for maintaining endolysosomal system organization and promoting receptor recycling.
- VPS45 plays a critical role in endosomal trafficking and is indispensable for early mouse embryogenesis.
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