期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 283, 期 19, 页码 13450-13458出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M709230200
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In response to oncogenic signals, cells have developed safe mechanisms to avoid transformation through activation of a senescence program. Upon v-H-Ras overexpression, normal cells undergo senescence through several cellular processes, including activation of the ERK1/2 pathway. Interestingly, the E1a gene from adenovirus 5 has been shown to rescue cells from senescence by a yet unknown mechanism. We investigated whether E1a was able to interfere with the ERK1/ 2 signaling pathway to rescue cells from v-H-Ras-mediated senescence. Our results show that, E1a overexpression blocks v-H-Ras-mediated ERK1/ 2 activation by two different and concomitant mechanisms. E1a through its ability to interfere with PKB/Akt activation induces the down-regulation of the PEA15 protein, an ERK1/ 2 nuclear export factor, leading to nuclear accumulation of ERK1/2. In addition to this, we show that E1a increases the expression of the inducible ERK1/ 2 nuclear phosphatases (MAPK phosphatases) MKP1/DUSP1 and DUSP5, which leads to ERK1/ 2 dephosphorylation. We confirmed our observations in the human normal diploid fibroblasts IMR90, in which we could also show that an E1a mutant, unable to bind retinoblastoma protein (pRb), cannot rescue cells from v-H-Ras-induced senescence. In conclusion, E1a is able to rescue from Ras-induced senescence by affecting ERK1/ 2 localization and phosphorylation.
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