title: Caspase activation is downstream of commitment to apoptosis of Ntera-2 neuronal cells.
abstract: Death by apoptosis is widespread among different cell types, including neurones. Apoptosis consists of a phase during which cells commit to die, followed by an execution phase, characterized by conserved morphological changes. To prevent neuronal loss during disease, it is important to identify the events which define irreversible commitment to death. The present study has investigated the events accompanying the commitment and execution phases of the neuronal cell line Ntera-2. In response to serum starvation, Ntera-2 cells enter the execution phase and detach into the culture supernatant with an apoptotic morphology. This phase is associated with activation of caspases. The remaining adherent cells have a normal morphology and can adhere to extracellular matrix substrates. However, after 96 h of serum deprivation, 95% of these adherent cells fail to form colonies in a single cell cloning assay. When refed with serum, 70% of these cells become apoptotic within 24 h, suggesting that they had previously committed to die. A further 20% of the cells escape from commitment to apoptosis by beginning to differentiate. Inhibition of caspases fails to delay commitment. In response to serum deprivation, therefore, neuronal cells either differentiate or commit to cell death, and events upstream of caspase activation regulate this irreversible commitment. These results have significant therapeutic implications since they suggest that caspase inhibitors may not promote long-term survival of every neuronal cell type in every situation.
authors.affiliation: School of Biological Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom. r.m.gibson@man.ac.uk
authors.forename: R M
authors.initials: RM
authors.lastname: Gibson
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002352:Carrier Proteins / Q000378:metabolism; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D048429:Cell Size / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D002999:Clone Cells; D003374:Coumarins / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D008840:Microfilament Proteins / Q000378:metabolism; D008970:Molecular Weight; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D009842:Oligopeptides / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D013049:Spectrin
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D020169:Caspases; D015815:Cell Adhesion Molecules; D002843:Chromatin; D003374:Coumarins; D016326:Extracellular Matrix Proteins; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D008840:Microfilament Proteins; D009842:Oligopeptides; D011065:Poly(ADP-ribose) Polymerases; D011505:Protein-Tyrosine Kinases; D013049:Spectrin; C112287:Ac-aspartyl-glutamyl-valyl-aspartyl-aminomethylcoumarin; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C496050:PTK2 protein, human