Ras proteins induce senescence by altering the intracellular levels of reactive oxygen species
Ras proteins induce senescence by altering the intracellular levels of reactive oxygen species
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DOI：
10.1074/jbc.274.12.7936
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发表时间：
1999-03-19
影响因子：
4.8
通讯作者：
Finkel, T
中科院分区：
文献类型：
--
作者：
Lee, AC;Fenster, BE;Finkel, T
人二倍体成纤维细胞最终失去在培养物中复制的能力，并进入存活但非增殖的衰老状态。最近，它已被证明，逆转录病毒介导的基因转移到原代成纤维细胞的激活ras基因（V12 ras）迅速加速衰老表型的发展，使用这个在体外系统，我们试图确定介质的RES诱导的衰老。我们表明，V12 Ras的表达导致细胞内，特别是线粒体活性氧的增加，V12 Ras诱导生长停滞和衰老的能力被证明是部分抑制由共表达的激活的RAD基因。当细胞被置于低氧环境中时，表现出对表达V12 Ras的细胞的更戏剧性的拯救，低氧环境是活性氧产生被抑制的条件。此外，在1%的氧气环境中，Res不能触发细胞周期蛋白依赖性激酶抑制剂p21水平的增加或激活衰老程序。在常氧（20%O-2）条件下，V12 Ras衰老表型被证明是不受超氧化物的清除剂，但拯救过氧化氢的清除剂。这些结果表明，在正常的二倍体细胞中，Ras蛋白调节氧化剂的产生和细胞内过氧化氢的上升代表了一个关键的信号介导复制衰老。
Human diploid fibroblasts eventually lose the capacity to replicate in culture and enter a viable but nonproliferative state of senescence. Recently, it has been demonstrated that retroviral-mediated gene transfer into primary fibroblasts of an activated ras gene (V12ras) rapidly accelerates development of the senescent phenotype, Using this in vitro system, we have sought to define the mediators of Res-induced senescence. We demonstrate that expression of V12Ras results in an increase in intracellular and in particular, mitochondrial reactive oxygen species, The ability of V12Ras to induce growth arrest and senescence is shown to be partially inhibited by coexpression of an activated rad gene. A more dramatic rescue of V12Ras-expressing cells is demonstrated when the cells are placed in a low oxygen environment, a condition in which reactive oxygen species production is inhibited. In addition, in a 1% oxygen environment, Res is unable to trigger an increase in the level of the cyclin-dependent kinase inhibitor p21 or to activate the senescent program. Under normoxic (20% O-2) conditions, the V12Ras senescent phenotype is demonstrated to be unaffected by scavengers of superoxide but rescued by scavengers of hydrogen peroxide. These results suggest that in normal diploid cells, Ras proteins regulate oxidant production and that a rise in intracellular H2O2 represents a critical signal mediating replicative senescence.