title: Granulysin delivered by cytotoxic cells damages endoplasmic reticulum and activates caspase-7 in target cells.
abstract: Granulysin is a human cytolytic molecule present in cytotoxic granules with perforin and granzymes. Recombinant 9-kDa granulysin kills a variety of microbes, including bacteria, yeast, fungi, and parasites, and induces apoptosis in tumor cells by causing intracellular calcium overload, mitochondrial damage, and activation of downstream caspases. Reasoning that granulysin delivered by cytotoxic cells may work in concert with other molecules, we crossed granulysin transgenic (GNLY(+/-)) mice onto perforin (perf)- or granzyme B (gzmb)-deficient mice to examine granulysin-mediated killing in a more physiologic whole-cell system. Splenocytes from these animals were activated in vitro with IL-15 to generate cytolytic T cells and NK cells. Cytotoxic cells expressing granulysin require perforin, but not granzyme B, to cause apoptosis of targets. Whereas granzyme B induces mitochondrial damage and activates caspases-3 and -9 in targets, cytotoxic cell-delivered granulysin induces endoplasmic reticulum stress and activates caspase-7 with no effect on mitochondria or caspases-3 and -9. In addition, recombinant granulysin and cell-delivered granulysin activate distinct apoptotic pathways in target cells. These findings suggest that cytotoxic cells have evolved multiple nonredundant cell death pathways, enabling host defense to counteract escape mechanisms employed by pathogens or tumor cells.
authors.affiliation: Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Reena V
authors.initials: RV
authors.lastname: Saini
authors.forename: Christine
authors.initials: C
authors.lastname: Wilson
authors.forename: Michael W
authors.initials: MW
authors.lastname: Finn
authors.forename: Tianhong
authors.initials: T
authors.lastname: Wang
authors.forename: Alan M
authors.initials: AM
authors.lastname: Krensky
authors.forename: Carol
authors.initials: C
authors.lastname: Clayberger
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism* / Q000633:toxicity*; D017209:Apoptosis / Q000276:immunology; D053179:Caspase 7 / Q000378:metabolism*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D003601:Cytotoxicity Tests, Immunologic; D004721:Endoplasmic Reticulum / Q000201:enzymology / Q000276:immunology* / Q000473:pathology*; D004789:Enzyme Activation / Q000276:immunology; D006801:Humans; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D015398:Signal Transduction / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000201:enzymology* / Q000276:immunology* / Q000473:pathology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; C075005:GNLY protein, human; C505524:Casp7 protein, mouse; D053179:Caspase 7