Inhibition of NF-kappa B activity in human T lymphocytes induces caspase-dependent apoptosis without detectable activation of caspase-1 and -3.
NF-kappa B is involved in the transcriptional control of various genes that act as extrinsic and intrinsic survival factors for T cells. Our findings show that suppression of NF-kappa B activity with cell-permeable SN50 peptide, which masks the nuclear localization sequence of NF-kappa B1 dimers and prevents their nuclear localization, induces apoptosis in resting normal human PBL. Inhibition of NF-kappa B resulted in the externalization of phosphatidylserine, induction of DNA breaks, and morphological changes consistent with apoptosis. DNA fragmentation was efficiently blocked by the caspase inhibitor Z-VAD-fmk and partially blocked by Ac-DEVD-fmk, suggesting that SN50-mediated apoptosis is caspase-dependent. Interestingly, apoptosis induced by NF-kappa B suppression, in contrast to that induced by TPEN (N,N,N',N'-tetrakis [2-pyridylmethyl]ethylenediamine) or soluble Fas ligand (CD95), was observed in the absence of active death effector proteases caspase-1-like (IL-1 converting enzyme), caspase-3-like (CPP32/Yama/apopain), and caspase-6-like and without cleavage of caspase-3 substrates poly(ADP-ribose) polymerase and DNA fragmentation factor-45. These findings suggest either low level of activation is required or that different caspases are involved. Preactivation of T cells resulting in NF-kappa B nuclear translocation protected cells from SN50-induced apoptosis. Our findings demonstrate an essential role of NF-kappa B in survival of naive PBL.
Department of Immunology, Cleveland Clinic Foundation, OH 44195, USA. kolenkv@ces.mtp.ccf.org
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Kolenko
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Bloom
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Rayman
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Bukowski
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Hsi
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Finke
D017209:Apoptosis / Q000187:drug effects / Q000276:immunology*; D020170:Caspase 1 / Q000378:metabolism*; D053148:Caspase 3; D053178:Caspase 6; D020169:Caspases / Q000378:metabolism* / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects / Q000276:immunology; D004789:Enzyme Activation / Q000276:immunology; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007399:Interphase / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology; D010455:Peptides / Q000502:physiology; D010718:Phosphatidylserines / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism*
D007166:Immunosuppressive Agents; D016328:NF-kappa B; D010455:Peptides; D010718:Phosphatidylserines; C118258:SN50 peptide; C505407:CASP3 protein, human; C505514:CASP6 protein, human; D053148:Caspase 3; D053178:Caspase 6; D020169:Caspases; D020170:Caspase 1