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Dictyostelium discoideum cells shed vesicles with associated DNA and vital stain Hoechst 33342
I Tatischeff1, M Bomsel, C de Paillerets
1Laboratoire de Physicochimie Biomoléculaire et Cellulaire, CNRS URA 2056, Université Pierre et Marie Curie, Paris, France. tati@lpbc.jussieu.fr
Abstract:
Dictyostelium discoideum cells are highly resistant to xenobiotics. We previously observed that these primitive eukaryotic cells contain a 170-kDa P-glycoprotein, mediating multidrug resistance in mammalian cells, but nonfunctional in Dictyostelium cells. We show here that D. discoideum cells vitally stained with the DNA-specific dye, Hoechst 33342, release fluorescent material in their culture medium. Electron microscopy and lipid analysis demonstrate the vesicular nature of this material. Moreover, nucleic acids associate with these extracellular vesicles independently of Hoechst vital staining. The main vesicular DNA component exhibits a size > 21 kb. Shedding of microvesicles during cell growth is not concomitant with programmed cell death. We propose that these extracellular vesicles are involved in a new cellular resistance mechanism against xenobiotics. Furthermore, since the association of DNA with vesicles occurs in physiological growth conditions and independently of vital staining, the new shedding process might be involved in a more general intercellular mechanism.
Insights
Dictyostelium discoideum cells release extracellular vesicles containing DNA. This novel shedding process may represent a new mechanism for cellular resistance to xenobiotics and intercellular communication.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Dictyostelium discoideum exhibits high xenobiotic resistance.
- A non-functional 170-kDa P-glycoprotein was previously identified in these cells.
- Existing resistance mechanisms in D. discoideum are not fully understood.
Purpose of the Study:
- To investigate the mechanism of xenobiotic resistance in Dictyostelium discoideum.
- To identify novel cellular components or processes involved in resistance.
- To explore the role of extracellular material in cellular defense.
Main Methods:
- Vital staining with Hoechst 33342.
- Electron microscopy.
- Lipid analysis.
- Nucleic acid analysis.
Main Results:
- D. discoideum cells release fluorescent material, identified as extracellular vesicles.
- These vesicles contain nucleic acids, primarily DNA fragments larger than 21 kb.
- Vesicle shedding occurs during normal cell growth, independent of vital staining or programmed cell death.
- Lipid analysis confirmed the vesicular nature of the shed material.
Conclusions:
- Dictyostelium discoideum sheds extracellular vesicles containing DNA during normal growth.
- This shedding process represents a potential new mechanism for xenobiotic resistance.
- The findings suggest a broader role in intercellular communication and defense.