Back to Search
Start Over
Disruption of the actin filament network affects delivery of endocytic contents marker to phagosomes with early endosome characteristics: the case of phagosomes with pathogenic mycobacteria
- Source :
- European journal of cell biology. 79(10)
- Publication Year :
- 2000
-
Abstract
- Phagosomes containing live virulent mycobacteria undergo fusion with early endosomes, but they are unable to mature normally. Accordingly, they do not fuse with lysosomes. Although M. avium-containing phagosomes retain fusion and intermingling characteristics of early endosomes indefinitely, fusions with early endosomes are increasingly restricted as bacteria multiply. In addition, when endocytic tracers, such as horseradish peroxidase (HRP), are added to M. avium-infected macrophages at 1 or up to 15 days after infection, an atypical time course of acquisition of the tracer by the phagosomes is observed, i.e., a 10 to 20 min lag, instead of immediate acquisition as is typical for early endosomes (and phagosomes with early endosome characteristics). These events coincide with a marked disorganization of the actin filament network in M. avium-infected macrophages. In the present study, we have therefore addressed the following question: Do actin filaments play a role in fusion and intermingling of contents between early endosomes and immature phagosomes that undergo homotypic fusion with early endosomes? We examined the time course of acquisition of subsequently internalized endocytic marker (HRP) by early endosome-like preexisting phagosomes, i.e. 2 hour-old phagosomes with either hydrophobic latex particles, virulent or avirulent M. avium, after depolymerization of the actin filament network with cytochalasin D or after repolymerization of the actin filament network with jasplakinolide, in cases where the network had been depolymerized (macrophages infected with M. avium, at 1 or up to 7 days after infection). By direct morphological observation at the electron microscope level and by a kinetic approach, we show here that depolymerization of the actin filament network with cytochalasin D delays acquisition of HRP whereas repolymerization restores immediate acquisition of the marker. We conclude that the actin filament network is involved in fusion and intermingling of endocytic contents between early endosomes and early endosome-like phagosomes, and that disruption of this network by M. avium is the cause for the atypical acquisition of content marker by phagosomes containing these pathogenic mycobacteria.
- Subjects :
- Histology
Antifungal Agents
Cytochalasin D
Time Factors
Endosome
Phagocytosis
Endocytic cycle
Bone Marrow Cells
Endosomes
Biology
Endocytosis
Peptides, Cyclic
Pathology and Forensic Medicine
Mycobacterium
Protein filament
chemistry.chemical_compound
Mice
Depsipeptides
Phagosomes
Animals
Actin
Cells, Cultured
Horseradish Peroxidase
Phagosome
Macrophages
Cell Biology
General Medicine
Actins
Cell biology
Mice, Inbred C57BL
Kinetics
Microscopy, Electron
chemistry
Microscopy, Fluorescence
Lysosomes
Subjects
Details
- ISSN :
- 01719335
- Volume :
- 79
- Issue :
- 10
- Database :
- OpenAIRE
- Journal :
- European journal of cell biology
- Accession number :
- edsair.doi.dedup.....4ce348b5c0812b450c92040084912524