title: Caspase-8 cleaves its substrates from the plasma membrane upon CD95-induced apoptosis.
abstract: Apoptosis occurs through a tightly regulated cascade of caspase activation. In the context of extrinsic apoptosis, caspase-8 is activated by dimerization inside a death receptor complex, cleaved by auto-proteolysis and subsequently released into the cytosol. This fully processed form of caspase-8 is thought to cleave its substrates BID and caspase-3. To test if the release is required for substrate cleavage, we developed a novel approach based on localization probes to quantitatively characterize the spatial-temporal activity of caspases in living single cells. Our study reveals that caspase-8 is significantly more active at the plasma membrane than within the cytosol upon CD95 activation. This differential activity is controlled by the cleavage of caspase-8 prodomain. As a consequence, targeting of caspase-8 substrates to the plasma membrane can significantly accelerate cell death. Subcellular compartmentalization of caspase-8 activity may serve to restrict enzymatic activity before mitochondrial pathway activation and offers new possibilities to interfere with apoptotic sensitivity of the cells.
authors.affiliation: Department for Bioinformatics and Functional Genomics, Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), Institute for Pharmacy and Molecular Biotechnology (IPMB) and BioQuant, Heidelberg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Beaudouin
authors.forename: C
authors.initials: C
authors.lastname: Liesche
authors.forename: S
authors.initials: S
authors.lastname: Aschenbrenner
authors.forename: M
authors.initials: M
authors.lastname: Hörner
authors.forename: R
authors.initials: R
authors.lastname: Eils
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein / Q000737:chemistry / Q000378:metabolism; D037281:Calnexin / Q000378:metabolism; D053148:Caspase 3 / Q000737:chemistry / Q000378:metabolism; D053178:Caspase 6 / Q000378:metabolism; D053181:Caspase 8 / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005456:Fluorescent Dyes / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D053533:Keratin-8 / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D013379:Substrate Specificity; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019014:fas Receptor / Q000378:metabolism*
chemical_list: D051023:BH3 Interacting Domain Death Agonist Protein; C525595:CISD1 protein, human; D005456:Fluorescent Dyes; D053533:Keratin-8; D024101:Mitochondrial Proteins; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; D037281:Calnexin; D003513:Cycloheximide; D053148:Caspase 3; D053178:Caspase 6; D053181:Caspase 8