Abstract
Granzyme B (GzmB) is a component of cytotoxic lymphocyte granules that can rapidly initiate apoptosis in target cells. While several procaspases are cleaved and activated by GzmB, the absolute requirement of caspase activation for GzmB-induced apoptosis is controversial. In this report, we demonstrate that GzmB can initiate apoptosis in the absence of caspase-3 activity by directly cleaving DFF45/ICAD to liberate activated DFF40/CAD. DFF45/ICAD cleavage occurs less efficiently in cells that lack caspase-3 activity, suggesting that the caspases normally amplify the GzmB death signal. DFF45/ICAD-deficient mouse embryo fibroblasts are partially resistant to GzmB-induced death, demonstrating the biological importance of DFF45/ICAD for GzmB-mediated apoptosis.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Apoptosis / genetics
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Apoptosis / immunology*
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Apoptosis Regulatory Proteins
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Caspase 3
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Caspases / metabolism
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Cell Line
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Cytotoxicity, Immunologic
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DNA Fragmentation / immunology*
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Deoxyribonucleases / antagonists & inhibitors*
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Embryo, Mammalian
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Enzyme Inhibitors / metabolism*
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Fibroblasts / cytology
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Fibroblasts / immunology
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Fibroblasts / metabolism
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Granzymes
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Immunity, Innate
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Killer Cells, Lymphokine-Activated / cytology
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Killer Cells, Lymphokine-Activated / enzymology
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Killer Cells, Lymphokine-Activated / immunology
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Mice
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Protein Processing, Post-Translational / immunology*
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Proteins / genetics
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Proteins / metabolism*
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Recombinant Proteins / metabolism
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Serine Endopeptidases / genetics
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Serine Endopeptidases / metabolism*
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Serine Endopeptidases / physiology
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Substrate Specificity
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T-Lymphocytes, Cytotoxic / cytology
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T-Lymphocytes, Cytotoxic / enzymology
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T-Lymphocytes, Cytotoxic / immunology
Substances
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Apoptosis Regulatory Proteins
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Enzyme Inhibitors
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Proteins
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Recombinant Proteins
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caspase-activated DNase inhibitor
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Deoxyribonucleases
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GZMB protein, human
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Granzymes
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Gzmb protein, mouse
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Serine Endopeptidases
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CASP3 protein, human
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Casp3 protein, mouse
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Caspase 3
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Caspases