title: Caspase-independent cell death and mitochondrial disruptions observed in the Apaf1-deficient cells.
abstract: Apaf1 is a critical molecule in the mitochondria-dependent apoptotic pathway. Here we show that Apaf1-deficient embryonic fibroblasts died at a later phase of apoptotic induction, although these cells were resistant to various apoptotic stimulants at an early phase. Neither caspase 3 activation nor nuclear condensation was observed during this cell death of Apaf1-deficient cells. Electron microscopic examination revealed that death in response to apoptotic stimulation resembled necrosis in that nuclei were round and swollen with low electron density. Necrosis-like cell death was also observed in wild-type cells treated with z-VAD-fmk. Mitochondria were not only morphologically abnormal but functionally affected, since mitochondrial transmembrane potential (DeltaPsim) was lost even in cells with intact plasma membrane integrity. These mitochondrial alterations were also observed in the wild-type cells dying of apoptosis. Combined, these data suggest that cells without caspase activation, such as Apaf1-deficient cells or cells treated with caspase inhibitors, die of necrosis-like cell death with mitochondrial damage in response to "apoptotic stimulation."
authors.affiliation: Department of Immunology and Department of Virology, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Miyazaki
authors.forename: H
authors.initials: H
authors.lastname: Yoshida
authors.forename: M
authors.initials: M
authors.lastname: Sasaki
authors.forename: H
authors.initials: H
authors.lastname: Hara
authors.forename: G
authors.initials: G
authors.lastname: Kimura
authors.forename: T W
authors.initials: TW
authors.lastname: Mak
authors.forename: K
authors.initials: K
authors.lastname: Nomoto
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053477:Apoptotic Protease-Activating Factor 1; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D005347:Fibroblasts; D017353:Gene Deletion; D007425:Intracellular Membranes / Q000187:drug effects / Q000648:ultrastructure; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D009336:Necrosis; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000590:Amino Acid Chloromethyl Ketones; C506593:Apaf1 protein, mouse; D053477:Apoptotic Protease-Activating Factor 1; D061945:Caspase Inhibitors; D011506:Proteins; C105034:acetyl-aspartyl-valyl-alanyl-aspartyl fluoromethyl ketone; D020169:Caspases; D019311:Staurosporine