端粒是位于真核细胞染色体末端的DNA-蛋白质复合体,在维持染色体稳定上起着重要的作用,并且与细胞的衰老、癌变有着密切的关系。本实验观察了DNA依赖性蛋白激酶(DNA-dependent protein kinase,DNA-PK)抑制剂-渥曼青霉素(wortmannin,WM)对H2O2诱导的HeLa细胞端粒DNA链断裂重连接效应。结果表明WM能够显著地抑制H2O2诱导的HeLa细胞端粒DNA链断裂后的重连接作用,提示DNA-PK参与了端粒DNA链断裂损伤的修复过程。
Telomeres are the repetitive G rich DNA sequences at the end of chromosomes and shorten at each round of cell division. Besides the incomplete DNA synthesis, single and double DNA strand breaks, if not repaired, also contribute to the telomere shortening. To assess the frequency of strand breaks in proliferating Hela cells, telomere fragments were released by alkaline denaturing and electrophoresis from cells embedded in agarose, blotted onto membrane, and detected by probe specific to telomere sequence. The quantity of telomere fragments released was estimated to be less than 0.4% of the total telomere content, which corresponded to less than one break per cell. Since the mean length of the terminal restriction fragments of the cells was about 7 kbp, the fragments detected would lead to less than 19 bp in mean telomere shortening.
