Caspase inhibition extends the commitment to neuronal death beyond cytochrome c release to the point of mitochondrial depolarization.
Nerve growth factor (NGF) deprivation induces a Bax-dependent, caspase-dependent programmed cell death in sympathetic neurons. We examined whether the release of cytochrome c was accompanied by the loss of mitochondrial membrane potential during sympathetic neuronal death. NGF- deprived, caspase inhibitor-treated mouse sympathetic neurons maintained mitochondrial membrane potential for 25-30 h after releasing cytochrome c. NGF- deprived sympathetic neurons became committed to die, as measured by the inability of cells to be rescued by NGF readdition, at the time of cytochrome c release. In the presence of caspase inhibitor, however, this commitment to death was extended beyond the point of cytochrome c release, but only up to the subsequent point of mitochondrial membrane potential loss. Caspase-9 deficiency also arrested NGF-deprived sympathetic neurons after release of cytochrome c, and permitted these neurons to be rescued with NGF readdition. Commitment to death in the NGF-deprived, caspase- 9-deficient sympathetic neurons was also coincident with the loss of mitochondrial membrane potential. Thus, caspase inhibition extended commitment to death in trophic factor-deprived sympathetic neurons and allowed recovery of neurons arrested after the loss of cytochrome c, but not beyond the subsequent loss of mitochondrial membrane potential.
Deshmukh
M
M
Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Kuida
K
K
Johnson
E M
EM
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000172:deficiency / Q000235:genetics; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism*; D005456:Fluorescent Dyes; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000201:enzymology*; D020932:Nerve Growth Factor / Q000172:deficiency / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D014966:Xanthenes; D051028:bcl-2-Associated X Protein
D000590:Amino Acid Chloromethyl Ketones; C494827:Bax protein, mouse; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D003574:Cytochrome c Group; D005456:Fluorescent Dyes; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D014966:Xanthenes; D051028:bcl-2-Associated X Protein; C103192:butyloxycarbonyl-O-methyl-aspartyl-fluoromethyl ketone; C121372:mitotracker orange; D020932:Nerve Growth Factor; C506434:Casp9 protein, mouse; D053453:Caspase 9; D020169:Caspases