Role of c-Fos/JunD in protecting stress-induced cell death.
OBJECTIVE
The exposure of mammalian cells to extracellular stress induces the expression of immediate early genes such as c-fos and c-jun and activates transcription factor activator protein-1 (AP-1). The purpose of the current study was to investigate the role of c-Fos and JunD in stress-induced cell death.


METHODS
We exposed cultured primary mouse embryonic fibroblasts (MEF) to ultraviolet light (UV-C) or hydrogen peroxide (H(2)O(2)). Induction of c-Fos and JunD and activation of MAPK/ERK1/2 signalling in the presence or absence of a MAPK inhibitor were analyzed by western blotting. Activation of AP-1 transcription factors was detected by the electrophoretic mobility shift assay and immunoprecipitation. Cell death was measured by changes in caspase 3 activities and nuclear morphology. Effects of c-Fos and JunD expression on cell death were investigated by transfection.


RESULTS
We found that the exposure of cultured primary MEF cells to UV or H(2)O(2) caused a significant increase in c-Fos and JunD protein levels. In addition, these two proteins formed complexes with each other and contributed to activation of AP-1 transcription complexes. More importantly, under both stress conditions, overexpression of JunD alone or overexpression of both c-Fos and JunD reduced caspase 3 activity and cell death. At the same time, UV irradiation activated the MAPK/ERK1/2 signalling pathway. The suppression of MEK1/ERK1/2 activation inhibited UV-induced expression of c-Fos and JunD and increased caspase 3 activity and cell death.


CONCLUSIONS
Our results suggest that both UV and H(2)O(2 )induce the activation of c-Fos/JunD AP-1 complexes resulting in the prevention of cell death. Moreover, UV irradiation-induced increases in c-Fos/JunD expression in primary MEF cells are mediated through the activation of the MAPK/ERK1/2 signalling pathway.
Zhou
H
H
Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences & Shanghai JiaoTong University School of Medicine, Shanghai, China.
Gao
J
J
Lu
Z Y
ZY
Lu
L
L
Dai
W
W
Xu
M
M
D000818:Animals; D016923:Cell Death / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D006861:Hydrogen Peroxide / Q000494:pharmacology; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014466:Ultraviolet Rays
D005419:Flavonoids; D016877:Oxidants; D047428:Protein Kinase Inhibitors; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D006861:Hydrogen Peroxide; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one