title: Caspase-9 processing by caspase-3 via a feedback amplification loop in vivo.
abstract: In contrast to the autoprocessing of caspase-9, little is known about the biological significance of caspase-9 processing by caspase-3 via a feedback loop in vivo. We prepared antisera against mouse caspase-9 cleavage sites so that only the activated form of mouse caspase-9 was recognized. Using these antisera and caspase-9- and caspase-3-deficient mouse embryonic fibroblasts, we demonstrated that mouse caspase-9 is initially autoprocessed at D(353) and D(368) at low levels during staurosporine-induced apoptosis, whereupon the D(368) and D(168) sites are preferentially processed over D(353) by activated caspase-3 as part of a feedback amplification loop. Ac-DEVD-MCA (caspase-3-like) and Ac-LEHD-MCA (caspase-9-like) cleavage activities clearly showed that caspase-9 autoprocessing was necessary for the activation of caspase-3, whereas full activation of caspase-3 and caspase-9 was achieved only through the feedback amplification loop. This feedback amplification loop also played a predominant role during programmed cell death of dorsal root ganglia neurons at mouse embryonic day 11.5.
authors.affiliation: Division of Development and Differentiation, National Institute of Neuroscience, NCNP, Kodaira, Tokyo 187-8502, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Fujita
authors.forename: J
authors.initials: J
authors.lastname: Egashira
authors.forename: K
authors.initials: K
authors.lastname: Urase
authors.forename: K
authors.initials: K
authors.lastname: Kuida
authors.forename: T
authors.initials: T
authors.lastname: Momoi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity; D017209:Apoptosis; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000502:physiology*; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000166:cytology* / Q000294:innervation / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D019311:Staurosporine / Q000494:pharmacology
chemical_list: D000906:Antibodies; D004791:Enzyme Inhibitors; C505409:Casp3 protein, mouse; C506434:Casp9 protein, mouse; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; D019311:Staurosporine