Prolonged activation of ERK1,2 induces FADD-independent caspase 8 activation and cell death.
Prolonged ERK/MAPK activation has been implicated in neuronal cell death in vitro and in vivo. We found that HEK293 cells, recently reported to express neuronal markers, are exquisitely sensitive to long term ERK stimulation. Activation of an inducible form of Raf-1 (Raf-1:ER) in HEK293 cells induced massive apoptosis characterized by DNA degradation, loss of plasma membrane integrity and PARP cleavage. Cell death required MEK activity and protein synthesis and occurred via the death receptor pathway independently of the mitochondrial pathway. Accordingly, prolonged ERK stimulation activated caspase 8 and strongly potentiated Fas signaling. The death receptor adaptator FADD was found to be rapidly induced upon ERK activation. However using RNA interference and ectopic expression, we demonstrated that neither FADD nor Fas were necessary for caspase 8 activation and cell death. These findings reveal that prolonged ERK/MAPK stimulation results in caspase 8 activation and cell death.
Institute of Signaling, Developmental Biology and Cancer Research, CNRS UMR6543, Université de Nice Sophia-Antipolis, Centre Antoine Lacassagne, 33 Ave Valombrose, 06189, Nice, France.
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Cagnol
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Van Obberghen-Schilling
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Chambard
D000818:Animals; D053181:Caspase 8 / Q000378:metabolism*; D016923:Cell Death / Q000502:physiology*; D002460:Cell Line; D004789:Enzyme Activation; D053200:Fas-Associated Death Domain Protein / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D015398:Signal Transduction / Q000502:physiology; D051020:bcl-X Protein / Q000235:genetics / Q000378:metabolism; D019014:fas Receptor / Q000235:genetics / Q000378:metabolism
C494811:BCL2L1 protein, human; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D051020:bcl-X Protein; D019014:fas Receptor; D019908:Proto-Oncogene Proteins c-raf; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D053181:Caspase 8