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Updated: Jul 28, 2026
08:51
The Microscopy-Based Assay to Study and Analyze the Recycling Endosomes using SNARE Trafficking
Published on: February 12, 2022
Relationship between endosomes and lysosomes.
J P Luzio1, B M Mullock, P R Pryor
1Department of Clinical Biochemistry and Wellcome Trust Centre for Molecular Mechanisms in Disease, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2XY, UK. JPL10@CAM.AC.UK
Biochemical Society Transactions
|August 11, 2001
Summary
Late endosomes fuse directly with lysosomes, forming a hybrid organelle. This organelle reforms lysosomes and acts as a cellular stomach for macromolecule hydrolysis.
Area of Science:
- Cell Biology
- Molecular Biology
- Organelle Biology
Background:
- Endocytosed macromolecules are delivered to lysosomes for degradation.
- Lysosomal delivery is crucial for cellular waste removal and nutrient recycling.
Purpose of the Study:
- To investigate the mechanism of direct fusion between late endosomes and lysosomes.
- To explore the re-formation of lysosomes from hybrid organelles.
- To determine the function of the resulting hybrid organelle.
Main Methods:
- Cell-free content mixing assay using rat liver late endosomes and lysosomes.
- Electron microscopy studies in intact cells.
- Analysis of SNARE complex involvement and calcium release.
Main Results:
- Direct fusion of late endosomes and lysosomes forms a hybrid organelle.
- Lysosome re-formation occurs via maturation, involving content condensation and protein removal.
- Fusion requires syntaxin 7 and lumenal calcium release.
Conclusions:
- Lysosomes can be viewed as secretory granules storing hydrolases between fusion events.
- The hybrid organelle functions as a 'cell stomach' for macromolecule hydrolysis.
- Understanding this fusion process offers insights into cellular degradation pathways.
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