Chiu S M, Friedman L R, Oleinick N L
Department of Radiology, Case Western Reserve University, Cleveland, Ohio 44106.
Radiat Res. 1989 Dec;120(3):545-51.
The production and removal of gamma-radiation-induced DNA-protein crosslinks (DPC) in nuclear matrix-associated newly replicated DNA were examined, as well as the relationship of DPC to DNA replication. In unirradiated, exponentially growing Chinese hamster V79 cells, DNA pulse labeled with [3H]thymidine was observed to be bound preferentially to protein. The pulse-labeled DNA subsequently became dissociated from protein. After a 30- to 60-min chase period, the level of labeled DNA in DPC was reduced to the same level as for bulk DNA. The radiation dose response for the formation of DPC was similar in newly replicated DNA that had been chased for various times and in mature chromatin DNA. Labeled DNA, in the DPC formed after 60 Gy, was rapidly removed from protein during the postirradiation incubation period. However, no recovery of DNA synthesis was observed, even after the majority of DPC were released. Thus either DPC are not the sole cause of the inhibition of DNA synthesis or their removal is not sufficient for DNA synthesis to resume.
研究了核基质相关新复制DNA中γ射线诱导的DNA-蛋白质交联（DPC）的产生和去除，以及DPC与DNA复制的关系。在未辐照、指数生长的中国仓鼠V79细胞中，观察到用[3H]胸腺嘧啶脉冲标记的DNA优先与蛋白质结合。随后，脉冲标记的DNA从蛋白质上解离。经过30至60分钟的追踪期后，DPC中标记DNA的水平降至与总体DNA相同的水平。在经过不同时间追踪的新复制DNA和成熟染色质DNA中，DPC形成的辐射剂量反应相似。60 Gy照射后形成的DPC中的标记DNA在辐照后孵育期内迅速从蛋白质上移除。然而，即使在大多数DPC被释放后，也未观察到DNA合成的恢复。因此，要么DPC不是抑制DNA合成的唯一原因，要么它们的去除不足以使DNA合成恢复。
