MILD HYPEROXIA SHORTENS TELOMERES AND INHIBITS PROLIFERATION OF FIBROBLASTS - A MODEL FOR SENESCENCE
MILD HYPEROXIA SHORTENS TELOMERES AND INHIBITS PROLIFERATION OF FIBROBLASTS - A MODEL FOR SENESCENCE
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DOI：
10.1006/excr.1995.1305
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发表时间：
1995-09-01
影响因子：
3.7
通讯作者：
LOTZE, C
中科院分区：
文献类型：
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作者：
VONZGLINICKI, T;SARETZKI, G;LOTZE, C
在40%氧分压下培养人WI-38成纤维细胞所施加的轻度氧化应激在一至三次群体倍增后不可逆地阻断增殖。在一般形态学和脂褐素积累方面，高氧阻断的细胞与衰老细胞相似。此外，他们，像衰老的成纤维细胞，被阻止优先在G1期，从DNA含量的测量，通过流式细胞术是显而易见的。Southern印迹法显示端粒缩短率从常氧条件下的90 bp/群体倍增增加到高氧条件下的500 bp/群体倍增。在每种情况下，如果达到约4kb的端粒截止长度，则增殖被阻断。端粒长度与不同氧化应激条件下增殖的最终抑制相关，而群体倍增水平则不相关，这一事实表明端粒缩短提供了衰老中细胞周期退出的信号。在有丝分裂后的细胞中，不再发生端粒缩短。然而，S1核酸酶的末端限制性片段的敏感性增加，表明非分裂成纤维细胞的端粒单链断裂的积累。这种效应在常氧和高氧培养下都有发现，尽管在更高氧化应激的条件下更明显。可以推测，在复制过程中单链断裂的积累和由此产生的远端单链片段的丢失可能是端粒缩短的主要原因，可能比不完全复制本身更重要。(C)出版社：Academic Press
Mild oxidative stress as exerted by culture of human WI-38 fibroblasts under 40% oxygen partial pressure blocks proliferation irreversibly after one to three population doublings. Hyperoxically blocked cells are similar to senescent ones in terms of general morphology and lipofuscin accumulation. Moreover, they, like senescent fibroblasts, are blocked preferentially in G1 as evident from DNA content measurements by how cytometry. Southern blotting of AluI- and HinfI-restricted genomic DNA shows an increase of the rate of telomere shortening from 90 bp per population doubling under normoxia to more than 500 bp per population doubling under hyperoxia. In every case, proliferation is blocked if a telomere cutoff length of about 4 kb is arrived at. The fact that telomere length correlates with the final inhibition of proliferation under conditions of varied oxidative stress, while the population doubling level does not, suggests that telomere shortening provides the signal for cell cycle exit in senescence. In postmitotic cells, no further telomere shortening occurs. However, the sensitivity of terminal restriction fragments to S1 nuclease increases, indicating the accumulation of single-strand breaks in telomeres of nondividing fibroblasts. This effect is found both under normoxic and hyperoxic culture, although it is more pronounced under conditions of higher oxidative stress. It might be speculated that accumulation of single-strand breaks and the resultant loss of distal single-stranded fragments during replication could be a major cause of telomere shortening, possibly more important than incomplete replication per se. (C) 1995 Academic Press, Inc.