title: Interdigital cell death can occur through a necrotic and caspase-independent pathway.
abstract: Programmed cell death in animals is usually associated with apoptotic morphology and requires caspase activation. Necrosis and caspase-independent cell death have been reported, but mostly in experimental conditions that lead some to question their existence it in vivo. Loss of interdigital cells in the mouse embryo, a paradigm of cell death during development [1], is known to include an apoptotic [2] and caspase-dependent [3] [4] mechanism. Here, we report that, when caspase activity was inhibited using drugs or when apoptosis was prevented genetically (using Hammertoe mutant mice, or mice homozygous for a mutation in the gene encoding APAF-1, a caspase-activating adaptor protein), interdigital cell death still occurred. This cell death was negative for the terminal-deoxynucleotidyl-mediated dUTP nick end-labelling (TUNEL) assay and there was no overall cell condensation. At the electron microscopy level, peculiar 'mottled' chromatin alterations and marked mitochondrial and membrane lesions, suggestive of classical necrotic cell death, were observed with no detectable phagocytosis and no local inflammatory response. Thus, in this developmental context, although caspase activity confers cell death with an apoptotic morphotype, in the absence of caspase activity an underlying mechanism independent of known caspases can also confer cell death, but with a necrotic morphotype. This cell death can go undetected when using apoptosis-specific methodology, and cannot be blocked by agents that act on caspases.
authors.affiliation: Centre d'Immunologie INSERM-CNRS de Marseille-Luminy Case 906, 13288, Marseille, Cedex 9, France.
authors.forename: M
authors.initials: M
authors.lastname: Chautan
authors.forename: G
authors.initials: G
authors.lastname: Chazal
authors.forename: F
authors.initials: F
authors.lastname: Cecconi
authors.forename: P
authors.initials: P
authors.lastname: Gruss
authors.forename: P
authors.initials: P
authors.lastname: Golstein
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D053477:Apoptotic Protease-Activating Factor 1; D019485:Bone Morphogenetic Proteins / Q000819:agonists / Q000502:physiology; D061945:Caspase Inhibitors; D020169:Caspases / Q000502:physiology*; D002843:Chromatin / Q000648:ultrastructure; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005314:Embryonic and Fetal Development; D005326:Fetal Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D006614:Hindlimb / Q000002:abnormalities / Q000196:embryology*; D020287:In Situ Nick-End Labeling; D051379:Mice; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D009024:Morphogenesis / Q000502:physiology; D009336:Necrosis; D015388:Organelles / Q000648:ultrastructure; D011506:Proteins / Q000235:genetics; D017978:Receptors, Growth Factor / Q000819:agonists; D015398:Signal Transduction / Q000187:drug effects; D016559:Tacrolimus / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C402181:15-O-desmethyl-FK 520; D000590:Amino Acid Chloromethyl Ketones; C506593:Apaf1 protein, mouse; D053477:Apoptotic Protease-Activating Factor 1; D019485:Bone Morphogenetic Proteins; D061945:Caspase Inhibitors; D002843:Chromatin; D015853:Cysteine Proteinase Inhibitors; D005326:Fetal Proteins; D011506:Proteins; D017978:Receptors, Growth Factor; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D020169:Caspases; D016559:Tacrolimus