Drp1 mediates caspase-independent type III cell death in normal and leukemic cells.
Ligation of CD47 triggers caspase-independent programmed cell death (PCD) in normal and leukemic cells. Here, we characterize the morphological and biochemical features of this type of death and show that it displays the hallmarks of type III PCD. A molecular and biochemical approach has led us to identify a key mediator of this type of death, dynamin-related protein 1 (Drp1). CD47 ligation induces Drp1 translocation from cytosol to mitochondria, a process controlled by chymotrypsin-like serine proteases. Once in mitochondria, Drp1 provokes an impairment of the mitochondrial electron transport chain, which results in dissipation of mitochondrial transmembrane potential, reactive oxygen species generation, and a drop in ATP levels. Surprisingly, neither the activation of the most representative proapoptotic members of the Bcl-2 family, such as Bax or Bak, nor the release of apoptogenic proteins AIF (apoptosis-inducing factor), cytochrome c, endonuclease G (EndoG), Omi/HtrA2, or Smac/DIABLO from mitochondria to cytosol is observed. Responsiveness of cells to CD47 ligation increases following Drp1 overexpression, while Drp1 downregulation confers resistance to CD47-mediated death. Importantly, in B-cell chronic lymphocytic leukemia cells, mRNA levels of Drp1 strongly correlate with death sensitivity. Thus, this previously unknown mechanism controlling caspase-independent type III PCD may provide the basis for novel therapeutic approaches to overcome apoptotic avoidance in malignant cells.
Apoptose et Système Immunitaire, CNRS-URA 1961, Institut Pasteur, 25 rue du Dr. Roux, 75015 Paris, France.
Marlène
M
Bras
Victor J
VJ
Yuste
Gaël
G
Roué
Sandrine
S
Barbier
Patricia
P
Sancho
Clémence
C
Virely
Manuel
M
Rubio
Sylvie
S
Baudet
Josep E
JE
Esquerda
Hélène
H
Merle-Béral
Marika
M
Sarfati
Santos A
SA
Susin
D021581:Active Transport, Cell Nucleus / Q000502:physiology; D051928:CD47 Antigen / Q000235:genetics / Q000378:metabolism; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death / Q000502:physiology*; D048430:Cell Shape; D002478:Cells, Cultured; D034281:Dynamins; D004579:Electron Transport / Q000502:physiology; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007938:Leukemia / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000502:physiology
D051928:CD47 Antigen; C497894:CD47 protein, human; D008869:Microtubule-Associated Proteins; D024101:Mitochondrial Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012697:Serine Endopeptidases; D020169:Caspases; D020558:GTP Phosphohydrolases; C110768:DNM1L protein, human; D034281:Dynamins