The apoptosis/autophagy paradox: autophagic vacuolization before apoptotic death
| Autor: | Eeva-Liisa Eskelinen, Paul Saftig, Abdelali Jalil, Anne-Laure Pauleau, Gérard Pierron, Rosa-Ana Gonzalez-Polo, Nathanael Larochette, Guido Kroemer, Sylvie Souquère, Patricia Boya |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Programmed cell death
Blotting Western Fluorescent Antibody Technique Apoptosis Vacuole Mitochondrion Transfection Cell Line Lysosomal-Associated Membrane Protein 2 Autophagy Humans Caspase biology LAMP1 Lysosome-Associated Membrane Glycoproteins Cell Biology Flow Cytometry Molecular biology Cell biology Microscopy Electron Vacuolization Vacuoles biology.protein RNA Interference Microscopy Polarization Lysosomes HeLa Cells |
| Zdroj: | Journal of Cell Science. 118:3091-3102 |
| ISSN: | 1477-9137 0021-9533 |
| DOI: | 10.1242/jcs.02447 |
| Popis: | Autophagic cell death is morphologically characterized by an accumulation of autophagic vacuoles. Here, we show that inactivation of LAMP2 by RNA interference or by homologous recombination leads to autophagic vacuolization in nutrient-depleted cells. Cells that lack LAMP2 expression showed an enhanced accumulation of vacuoles carrying the marker LC3, yet a decreased colocalization of LC3 and lysosomes, suggesting that the fusion between autophagic vacuoles and lysosomes was inhibited. While a fraction of mitochondria from starved LAMP2-expressing cells colocalized with lysosomal markers, within autophagolysosomes, no such colocalization was found on removal of LAMP2 from the experimental system. Of note, LAMP1 depletion had no such effects and did not aggravate the phenotype induced by LAMP2-specific small interfering RNA. Serum and amino acid-starved LAMP2-negative cells exhibited an accumulation of autophagic vacuoles and then succumbed to cell death with hallmarks of apoptosis such as loss of the mitochondrial transmembrane potential, caspase activation and chromatin condensation. While caspase inhibition retarded cell death, it had no protective effect on mitochondria. Stabilization of mitochondria by overexpression of Bcl-2 or the mitochondrion-targeted cytomegalovirus protein vMIA, however, blocked all signs of apoptosis. Neither caspase inhibition nor mitochondrial stabilization antagonized autophagic vacuolization in LAMP2-deficient cells. Altogether, these data indicate that accumulation of autophagic vacuoles can precede apoptotic cell death. These findings argue against the clear-cut distinction between type 1 (apoptotic) and type 2 (autophagic) cell death. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|