ATM protein is required for radiation-induced apoptosis and acts before mitochondrial collapse.
Int J Radiat Biol
; 76(6): 841-51, 2000 Jun.
Article
en En
| MEDLINE
| ID: mdl-10902739
ABSTRACT
PURPOSE:
To define the role of the ataxia telangiectasia (A-T) mutated gene (ATM) in activation and progress of apoptosis. MATERIAL ANDMETHODS:
Three normal and three A-T EBV-transformed cell lines were studied. Following irradiation (IR), Fas activation or ceramide exposure, viability and apoptosis were measured by trypan blue dye exclusion assay and as sub-G1 cell fraction by flow cytometric analysis of propidium iodide stained cultures, respectively. Activation of caspase-3 was evaluated by immunoblot and by an in vitro activity assay on cytosolic cell extracts. To assess changes in mitochondrial potential and reactive oxygen species, cells were stained by 3,3'-dihexyloxacarbocynine iodide or hydroethidine, respectively, and scored by flow cytometry.RESULTS:
The observations establish that A-T cells are equipped with a proficient apoptotic machinery, as demonstrated by their ability to undergo mitochondrial collapse and caspase-3 activation after Fas activation or ceramide treatment. Both treatments have a similar cytotoxic effect on normal and A-T cells. In contrast, in spite of the stronger cytotoxicity induced by IR exposure, irradiated A-T cells are unable to undergo mitochondrial collapse and caspase-3 activation.CONCLUSIONS:
The data indicate that ATM is necessary in the initiation of molecular pathway(s) leading to IR-induced apoptosis, and suggest that increased radiosensitivity of A-T cells is more likely a direct consequence of necrotic cell death.
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Base de datos:
MEDLINE
Asunto principal:
Ataxia Telangiectasia
/
Proteínas Serina-Treonina Quinasas
/
Apoptosis
/
Mitocondrias
Idioma:
En
Revista:
Int J Radiat Biol
Asunto de la revista:
RADIOLOGIA
Año:
2000
Tipo del documento:
Article