Granzyme A Loading Induces Rapid Cytolysis and a Novel Form of DNA Damage Independently of Caspase Activation

Cytotoxic lymphocytes trigger apoptosis by releasing perforin and granzymes (Grn). GrnB activates the caspase apoptotic pathway, but little is known about GrnA-induced cell death. Perforin was used to load recombinant GrnA and GrnB and enzymatically inactive variants into target cells. GrnA induces...

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Bibliographic Details
Published in:Immunity (Cambridge, Mass.) Mass.), 1999-05, Vol.10 (5), p.585-595
Main Authors: Beresford, Paul J, Xia, Zhinan, Greenberg, Arnold H, Lieberman, Judy
Format: Article
Language:English
Subjects:
Animals
Apoptosis - drug effects
Caspases - metabolism
Cytotoxicity, Immunologic - drug effects
DNA Damage
Enzyme Activation
Esterases - metabolism
Gene Expression
Genes, bcl-2 - genetics
Granzymes
Humans
K562 Cells - drug effects
Serine Endopeptidases - pharmacology
T-Lymphocytes, Cytotoxic - drug effects
Tumor Cells, Cultured
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Summary:Cytotoxic lymphocytes trigger apoptosis by releasing perforin and granzymes (Grn). GrnB activates the caspase apoptotic pathway, but little is known about GrnA-induced cell death. Perforin was used to load recombinant GrnA and GrnB and enzymatically inactive variants into target cells. GrnA induces single-strand DNA breaks that can be labeled with Klenow polymerase and visualized on alkaline gels. GrnA-induced DNA damage but not cytolysis requires GrnA proteolysis. GrnA-induced membrane perturbation, nuclear condensation, and DNA damage are unimpaired by caspase blockade. GrnA fails to induce cleavage of caspase-3, lamin B, rho-GTPase, or PARP. GrnA-induced cytotoxicity and cleavage of PHAP II, a previously identified GrnA substrate, are unimpaired in Jurkat cells that overexpress bcl-2. Therefore, GrnA activates a novel apoptotic pathway.
ISSN:1074-7613
1097-4180
DOI:10.1016/S1074-7613(00)80058-8