GD3, an overexpressed tumor-derived ganglioside, mediates the apoptosis of activated but not resting T cells.
We previously elucidated an important role for gangliosides in renal cell carcinoma-mediated T lymphocyte apoptosis, although the mechanism by which they mediated lymphocyte death remained unclear. Here, we show that when added in purified form, GD3 is internalized by activated T cells, initiating a series of proapoptotic events, including the induction of reactive oxygen species (ROS), an enhancement of p53 and Bax accumulation, an increase in mitochondrial permeability, cytochrome c release, and the activation of caspase-9. GD3-induced apoptosis of activated T cells was dose dependent and inhibitable by pretreating the lymphocytes with N-acetylcysteine, cyclosporin A, or bongkrekic acid, emphasizing the essential role of ROS and mitochondrial permeability to the process. Ganglioside-induced T-cell killing was associated with the caspase-dependent degradation of nuclear factor-kappaB-inducible, antiapoptotic proteins, including RelA; this suggests that their loss is initiated only after the cascade is activated and that their disappearance amplifies but not triggers GD3 susceptibility. Resting T cells did not internalize appreciable levels of GD3 and did not undergo any of the proapoptotic changes that characterize activated T lymphocytes exposed to the ganglioside. RelA overexpression endows Jurkat cells with resistance to GD3-mediated apoptosis, verifying the role of the intact transcription factor in mediating protection from the ganglioside.
Sa
Gaurisankar
G
Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA.
Das
Tanya
T
Moon
Christina
C
Hilston
Cynthia M
CM
Rayman
Patricia A
PA
Rini
Brian I
BI
Tannenbaum
Charles S
CS
Finke
James H
JH
D000111:Acetylcysteine / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology*; D002292:Carcinoma, Renal Cell / Q000276:immunology / Q000473:pathology; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D061945:Caspase Inhibitors; D045744:Cell Line, Tumor; D002463:Cell Membrane Permeability; D045304:Cytochromes c / Q000276:immunology / Q000378:metabolism; D005732:Gangliosides / Q000276:immunology* / Q000493:pharmacokinetics; D005909:Glioblastoma / Q000276:immunology / Q000473:pathology; D006801:Humans; D019169:Jurkat Cells; D007680:Kidney Neoplasms / Q000276:immunology / Q000473:pathology; D008213:Lymphocyte Activation; D051336:Mitochondrial Membranes / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism
D000975:Antioxidants; D061945:Caspase Inhibitors; D005732:Gangliosides; D017382:Reactive Oxygen Species; C026226:ganglioside, GD3; D045304:Cytochromes c; C505530:CASP8 protein, human; D053181:Caspase 8; D053453:Caspase 9; D000111:Acetylcysteine