Central role of the proteasome in senescence and survival of human fibroblasts - Induction of a senescence-like phenotype upon its inhibition and resistance to stress upon its activation
Central role of the proteasome in senescence and survival of human fibroblasts - Induction of a senescence-like phenotype upon its inhibition and resistance to stress upon its activation
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DOI：
10.1074/jbc.m301048200
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发表时间：
2003-07-25
影响因子：
4.8
通讯作者：
Gonos, ES
中科院分区：
文献类型：
--
作者：
Chondrogianni, N;Stratford, FLL;Gonos, ES
正常的人类成纤维细胞在培养中经历有限的分裂，并逐渐达到不可逆转的生长停滞状态，这一过程被称为复制性衰老。蛋白酶体是主要的细胞蛋白水解机制，其功能在复制衰老过程中受损。然而，在这些情况下其故障的确切原因尚不清楚。使用WI38成纤维细胞作为细胞衰老模型，我们观察到衰老细胞中蛋白酶体肽酶活性水平降低，氧化蛋白和泛素化蛋白水平升高。我们发现20s复合物的催化亚基和19s调控复合物的亚基在衰老细胞中下调。这伴随着20 S和26 S复合物水平的下降。在年轻细胞中，用特异性抑制剂治疗引起的蛋白酶体的部分抑制诱导了类似衰老的表型，从而证明了蛋白酶体对维持细胞维持和体内平衡的基本重要性。在WI38建立的细胞系中，β(1)和β(5)亚基的稳定过表达可诱导β(5)转染物中β(1)亚基的表达水平升高，反之亦然。转染具有增加的蛋白酶体活性，最重要的是，增加了更好地应对各种胁迫的能力。总之，这些数据证明了蛋白酶体在细胞衰老和存活过程中的核心作用，并为更好地理解蛋白酶体调控提供了见解。
Normal human fibroblasts undergo a limited number of divisions in culture and progressively they reach a state of irreversible growth arrest, a process termed as replicative senescence. The proteasome is the major cellular proteolytic machinery, the function of which is impaired during replicative senescence. However, the exact causes of its malfunction in these conditions are unknown. Using WI38 fibroblasts as a model for cellular senescence we have observed reduced levels of proteasomal peptidase activities coupled with increased levels of both oxidized and ubiquitinated proteins in senescent cells. We have found the catalytic subunits of the 20 S complex and subunits of the 19 S regulatory complex to be down-regulated in senescent cells. This is accompanied by a decrease in the level of both 20 S and 26 S complexes. Partial inhibition of proteasomes in young cells caused by treatment with specific inhibitors induced a senescence-like phenotype, thus demonstrating the fundamental importance of the proteasome for retaining cellular maintenance and homeostasis. Stable overexpression of beta(1) and beta(5) subunits in WI38 established cell lines was shown to induce elevated expression levels of beta(1) subunit in beta(5) transfectants and vice versa. Transfectants possess increased proteasome activities and most importantly, increased capacity to cope better with various stresses. In summary these data demonstrate the central role of the proteasome during cellular senescence and survival as well as provide insights toward a better understanding of proteasome regulation.