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Multivesicular bodies in HEp-2 cells are maturing endosomes
B van Deurs1, P K Holm, L Kayser
1Department of Medical Anatomy, Panum Institute, University of Copenhagen, Denmark.
European Journal of Cell Biology
|August 1, 1993
Summary
This study reveals that multivesicular bodies (MVBs) in HEp-2 cells mature gradually, changing morphology and protein content over time. This process distinguishes early and late MVBs, offering insights into endosomal trafficking and lysosome formation.
Area of Science:
- Cell Biology
- Endosomal Trafficking
- Lysosome Biogenesis
Background:
- Endocytosis is a fundamental cellular process for internalizing molecules.
- Multivesicular bodies (MVBs) are key intermediates in endosomal sorting and degradation.
- Understanding MVB maturation is crucial for comprehending cellular homeostasis and disease.
Purpose of the Study:
- To investigate the dynamic maturation process of MVBs in HEp-2 cells.
- To characterize morphological and molecular changes during MVB to lysosome transition.
- To differentiate early and late MVB stages based on ultrastructural and protein markers.
Main Methods:
- Live-cell video microscopy using transferrin-Texas Red (Tf-TxR) tracer.
- Quantitative ultrastructural analysis with horseradish peroxidase (HRP) and cationized gold.
- Immunogold labeling on ultracryosections to detect specific marker proteins (TfRs, MPRs, lamp-1).
Main Results:
- MVBs are the predominant endocytic compartments in HEp-2 cells.
- MVB morphology changes gradually, with increasing internal vesicles and membranous material.
- Distinct protein markers (TfRs, MPRs, lamp-1) localize to specific MVB maturation stages.
Conclusions:
- HEp-2 cell MVBs undergo a gradual maturation process, distinguishable by morphology and protein composition.
- This maturation pathway leads to the formation of lysosomes containing internal vesicles and degradation products.
- The findings provide a framework for understanding endosomal sorting and lysosomal degradation dynamics.