ATP-dependent steps in apoptotic signal transduction.
Apoptotic changes of the nucleus induced by Fas (Apo1/CD95) stimulation are completely blocked by reducing intracellular ATP level. In this study, we examined the ATP-dependent step(s) of Fas-mediated apoptotic signal transduction using two cell lines. In SKW6.4 (type I) cells characterized by rapid formation of the death-inducing signaling complex on Fas treatment, the activation of caspases 8, 9, and 3, cleavage of DFF45 (ICAD), and release of cytochrome c from the mitochondria to the cytoplasm were not affected by reduction of intracellular ATP, although chromatin condensation and nuclear fragmentation were inhibited. On the other hand, in the Fas-mediated apoptosis of Jurkat (type II) cells, which is characterized by involvement of mitochondria and, thus, shares signal transduction mechanisms with apoptosis induced by other stimuli such as genotoxins, activation of the three caspases, cleavage of DFF45 (ICAD), and nuclear changes were blocked by reduction of intracellular ATP, whereas release of cytochrome c was not affected. These results suggested that the ATP-dependent step(s) of Fas-mediated apoptotic signal transduction in type I cells are only located downstream of caspase 3 activation, whereas the activation of caspase 9 by released cytochrome c is the most upstream ATP-dependent step in type II cells. These observations also confirm the existence of two pathways for Fas-mediated apoptotic signal transduction and suggest that the Apaf-1 (Ced-4 homologue) system for caspase 9 activation operates in an ATP-dependent manner in vivo.
Eguchi
Y
Y
Department of Medical Genetics, Biomedical Research Center, Osaka University Medical School, Suita, Japan.
Srinivasan
A
A
Tomaselli
K J
KJ
Shimizu
S
S
Tsujimoto
Y
Y
D000255:Adenosine Triphosphate / Q000502:physiology*; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D001402:B-Lymphocytes; D020169:Caspases / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation; D004789:Enzyme Activation; D004790:Enzyme Induction; D053222:Fas Ligand Protein; D006019:Glycolysis / Q000187:drug effects; D006801:Humans; D019169:Jurkat Cells; D008214:Lymphocytes / Q000166:cytology*; D008562:Membrane Glycoproteins / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism; D009840:Oligomycins / Q000633:toxicity; D011506:Proteins / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors; D015398:Signal Transduction / Q000502:physiology*; D019014:fas Receptor / Q000502:physiology
D051017:Apoptosis Regulatory Proteins; D003574:Cytochrome c Group; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D009840:Oligomycins; D011506:Proteins; C109664:caspase-activated DNase inhibitor; D019014:fas Receptor; D000255:Adenosine Triphosphate; D020169:Caspases; D006180:Proton-Translocating ATPases