Loss of Mcl-1 protein and inhibition of electron transport chain together induce anoxic cell death.
How cells die in the absence of oxygen (anoxia) is not understood. Here we report that cells deficient in Bax and Bak or caspase-9 do not undergo anoxia-induced cell death. However, the caspase-9 null cells do not survive reoxygenation due to the generation of mitochondrial reactive oxygen species. The individual loss of Bim, Bid, Puma, Noxa, Bad, caspase-2, or hypoxia-inducible factor 1beta, which are potential upstream regulators of Bax or Bak, did not prevent anoxia-induced cell death. Anoxia triggered the loss of the Mcl-1 protein upstream of Bax/Bak activation. Cells containing a mitochondrial DNA cytochrome b 4-base-pair deletion ([rho(-)] cells) and cells depleted of their entire mitochondrial DNA ([rho(0)] cells) are oxidative phosphorylation incompetent and displayed loss of the Mcl-1 protein under anoxia. [rho(0)] cells, in contrast to [rho(-)] cells, did not die under anoxia. However, [rho(0)] cells did undergo cell death in the presence of the Bad BH3 peptide, an inhibitor of Bcl-X(L)/Bcl-2 proteins. These results indicate that [rho(0)] cells survive under anoxia despite the loss of Mcl-1 protein due to residual prosurvival activity of the Bcl-X(L)/Bcl-2 proteins. Collectively, these results demonstrate that anoxia-induced cell death requires the loss of Mcl-1 protein and inhibition of the electron transport chain to negate Bcl-X(L)/Bcl-2 proteins.
Brunelle
Joslyn K
JK
Department of Medicine, Northwestern University Medical School, 240 East Huron Avenue, Chicago, IL 60611, USA.
Shroff
Emelyn H
EH
Perlman
Harris
H
Strasser
Andreas
A
Moraes
Carlos T
CT
Flavell
Richard A
RA
Danial
Nika N
NN
Keith
Brian
B
Thompson
Craig B
CB
Chandel
Navdeep S
NS
D000222:Adaptation, Physiological / Q000187:drug effects; D000818:Animals; D053453:Caspase 9 / Q000172:deficiency / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects; D045303:Cytochromes b / Q000235:genetics; D004272:DNA, Mitochondrial / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D006019:Glycolysis / Q000187:drug effects; D006801:Humans; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000172:deficiency* / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology; D017434:Protein Structure, Tertiary / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000172:deficiency* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D017384:Sequence Deletion; D014407:Tumor Cells, Cultured
D004272:DNA, Mitochondrial; D051793:Hypoxia-Inducible Factor 1; C579094:Mcl1 protein, mouse; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D045303:Cytochromes b; D053453:Caspase 9; D010100:Oxygen