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APOPTOSIS INDUCED BY γ IRRADIATION IN PERIPHERAL BLOOD MONONUCLEAR CELLS IS NOT MEDIATED BY CYTOCHROME‐C RELEASE AND ONLY PARTIALLY INVOLVES CASPASE‐3‐LIKE PROTEASES
Author(s) -
Louagie H.,
Schotte P.,
Vral A.,
Cornelissen M.,
Thierens H.,
Beyaert R.,
Ridder L.,
Philippe J.
Publication year - 1999
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1006/cbir.1999.0429
Subject(s) - cytochrome c , apoptosis , dna fragmentation , caspase , microbiology and biotechnology , tunel assay , caspase 9 , caspase 3 , cytochrome , peripheral blood mononuclear cell , fragmentation (computing) , biology , chemistry , programmed cell death , biochemistry , enzyme , in vitro , ecology
Caspase 3 has been shown to be actively involved in the apoptotic process in thymocytes after γ‐irradiation. We examined caspase 3 activation in mature peripheral blood lymphocytes (PBL) after γ irradiation. Since the activation of caspase 3 is generally prceded by a decrease in mitochondrial membrane potential (ΔΨm) and cytochrome c release, these two parameters were also examined. Apoptosis in PBL after a 5‐Gy γ irradiation, is characterized by a decrease in ΔΨm, but surprisingly no release of cytochrome‐c and only a weak caspase 3 activation was noticed. In contrast, staurosporin treated PBL showed a decrease in ΔΨm with cytochrome‐c release and a clear caspase 3 activation. We were unable to block the decrease in ΔΨm with the caspase‐inhibitors zVAD‐fmk or zDEVD‐fmk after γ irradiation, but DNA fragmentation as measured by the TUNEL assay was partially inhibited. Therefore, in γ irradiated mature PBL, caspase‐dependent and ‐independent pathways, but not cytochrome c, seem to be involved in the apoptotic process.