Inhibiting Drp1-mediated mitochondrial fission selectively prevents the release of cytochrome c during apoptosis.
Most cell death stimuli trigger the mitochondrial release of cytochrome c and other cofactors that induce caspase activation and ensuing apoptosis. Apoptosis is also associated with massive mitochondrial fragmentation and cristae remodeling. Dynamin-related protein 1 (Drp1), a protein of the mitochondrial fission machinery, has been reported to participate in apoptotic mitochondrial fragmentation. Several theories explaining the mechanisms of cytochrome c release have been proposed. One suggests that it relies on the activation of Drp1-mediated mitochondrial fission. Here, we report that downregulation of Drp1 inhibits fragmentation of the mitochondrial network and partially prevents the release of cytochrome c but fails to prevent the release of other mitochondrial factors such as second mitochondria-derived activator of caspase/direct IAP-binding protein with low pI, Omi/HtrA2, adenylate kinase 2 and deafness dystonia peptide/TIMM8a. An explanation for the prevention of cytochrome c release is provided by our observation that inhibiting Drp1-mediated mitochondrial fission prevents the mitochondrial release of soluble OPA1 that was proposed to regulate cristae remodeling and complete cytochrome c release during apoptosis. Finally, we observed that downregulation of Drp1 delays but does not inhibit apoptosis, suggesting that mitochondrial fragmentation is not a prerequisite for apoptosis.
Estaquier
J
J
Unité de Physiopathologie des Infections Lentivirales, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris cedex 15, France.
Arnoult
D
D
D000263:Adenylate Kinase / Q000378:metabolism; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism*; D034281:Dynamins; D005434:Flow Cytometry; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006367:HeLa Cells; D000074923:High-Temperature Requirement A Serine Peptidase 2; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism / Q000502:physiology*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D034622:RNA Interference; D012697:Serine Endopeptidases / Q000378:metabolism
D007527:Isoenzymes; D026901:Membrane Transport Proteins; D008869:Microtubule-Associated Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; C118122:TIMM8A protein, human; D045304:Cytochromes c; D000263:Adenylate Kinase; C110938:adenylate kinase 2; D012697:Serine Endopeptidases; C000615914:HTRA2 protein, human; D000074923:High-Temperature Requirement A Serine Peptidase 2; D020169:Caspases; D020558:GTP Phosphohydrolases; C415198:OPA1 protein, human; C110768:DNM1L protein, human; D034281:Dynamins