PKC activation contributes to caspase-mediated eIF2alpha phosphorylation and cell death.
Biochim Biophys Acta
; 1800(5): 518-25, 2010 May.
Article
em En
| MEDLINE
| ID: mdl-20123115
ABSTRACT
BACKGROUND:
Stress-induced phosphorylation of the alpha-subunit of eukaryotic initiation factor 2 (eIF2alpha), involved in translation, promotes cell suicide or survival. Since multiple signaling pathways are implicated in cell death, the present study has analyzed the importance of PKC activation in the stress-induced eIF2alpha phosphorylation, caspase activation and cell death in the ovarian cells of Spodoptera frugiperda (Sf9) and in their extracts.METHODS:
Cell death is analyzed by flow cytometry. Caspase activation is measured by Ac-DEVD-AFC hydrolysis and also by the cleavage of purified recombinant PERK, an endoplasmic reticulum-resident eIF2alpha kinase. Status of eIF2alpha phosphorylation and cytochrome c levels are analyzed by western blots.RESULTS:
PMA, an activator of PKC, does not promote cell death or affect eIF2alpha phosphorylation. However, PMA enhances late stages of UV-irradiation or cycloheximide-induced caspase activation, eIF2alpha phosphorylation and apoptosis in Sf9 cells. PMA also enhances cytochrome c-induced caspase activation and eIF2alpha phosphorylation in cell extracts. These changes are mitigated more efficiently by caspase inhibitor, z-VAD-fmk, than by calphostin, an inhibitor of PKC. In contrast, tunicamycin-induced eIF2alpha phosphorylation that does not lead to caspase activation or cell death is unaffected by PMA, z-VAD-fmk or by calphostin.CONCLUSIONS:
While caspase activation is a cause and consequence of eIF2alpha phosphorylation, PKC activation that follows caspase activation further enhances caspase activation, eIF2alpha phosphorylation, and cell death in Sf9 cells. GENERALSIGNIFICANCE:
Caspases can activate multiple signaling pathways to enhance cell death.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Estresse Fisiológico
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Proteína Quinase C
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Fator de Iniciação 2 em Eucariotos
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Proteínas de Insetos
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Caspases
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article