Induction of cytochrome c-mediated apoptosis by amyloid beta 25-35 requires functional mitochondria.
Accumulating data suggest a central role for mitochondria and oxidative stress in neurodegenerative apoptosis. We previously demonstrated that amyloid-beta peptide 25-35 (Abeta 25-35) toxicity in cultured cells is mediated by its effects on functioning mitochondria. In this study, we further explored the hypothesis that Abeta 25-35 might induce apoptotic cell death by altering mitochondrial physiology. Mitochondria in Ntera2 (NT2 rho+) human teratocarcinoma cells exposed to either staurosporine (STS) or Abeta 25-35 were found to release cytochrome c, with subsequent activation of caspases 9 and 3. However, NT2 cells depleted of mitochondrial DNA (rho0 cells), which maintain a normal mitochondrial membrane potential (Deltapsi(m)) despite the absence of a functional electron transport chain (ETC), demonstrated cytochrome c release and caspase activation only with STS. We further observed increased reactive oxygen species (ROS) production and decreased reduced glutathione (GSH) levels in rho+ and rho0 cells treated with STS, but only in rho+ cells treated with Abeta 25-35. We conclude that under in vitro conditions, Abeta can induce oxidative stress and apoptosis only when a functional mitochondrial ETC is present.
Morais Cardoso
Sandra
S
Center for Neuroscience of Coimbra, University of Coimbra, 3004-5004, Portugal. scardoso@cnc.cj.uc.pt
Swerdlow
Russell H
RH
Oliveira
Catarina R
CR
D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003574:Cytochrome c Group / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D018384:Oxidative Stress; D010446:Peptide Fragments / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D019311:Staurosporine / Q000494:pharmacology; D018243:Teratocarcinoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D014407:Tumor Cells, Cultured
D016229:Amyloid beta-Peptides; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D017382:Reactive Oxygen Species; C074636:amyloid beta-protein (25-35); C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; D005978:Glutathione; D019311:Staurosporine