The non‐homologous end‐joining pathway is not involved in the radiosensitization of mammalian cells by heat shock
The non‐homologous end‐joining pathway is not involved in the radiosensitization of mammalian cells by heat shock
复制标题
非同源末端连接途径不参与哺乳动物细胞热休克的放射增敏作用
DOI：
--
复制
发表时间：
2003
影响因子：
5.6
通讯作者：
B. D. Beck
中科院分区：
文献类型：
--
作者：
J. Dynlacht;M. Bittner;J. A. Bethel;B. D. Beck
当在暴露于电离辐射（IR）之前、期间或之后立即给予热休克时，观察到细胞杀伤的协同增加。这种现象被称为热辐射增敏，被认为是当细胞暴露于42°C以上的温度时，通过抑制辐射诱导的双链断裂（DSB）的修复来介导的。然而，热抑制DSB修复的机制尚不清楚。大部分辐射诱导的DSB通过非同源末端连接途径（NHEJ）修复。一些报告表明，哺乳动物DNA依赖性蛋白激酶（DNA-PK）的Ku 70和Ku 80亚基（一种参与NHEJ的复合物）似乎对热诱导的DNA结合活性丧失敏感，Ku 80代表热敏组分。由于Ku-DNA结合活性的热诱导损失和随后的恢复与热辐射增敏密切相关，因此提出了Ku 80和NHEJ在热辐射增敏中的作用。然而，直接证据表明Ku 80（和NHEJ）在热辐射增敏中的作用尚不确定。在这项研究中，我们证明了在42.5-45.5°C的等毒性热处理诱导人U-1黑色素瘤细胞中类似量的Ku 80聚集。这些数据表明，热致死率和Ku 80聚集之间的时间-温度依赖性关系相似。然而，Ku 80的聚集/解聚及其短暂或永久失活与热辐射增敏无关。当获得辐照或辐照和加热的Ku 80 −/−小鼠胚胎成纤维细胞（MEFs）的存活曲线并与野生型（WT）细胞的存活曲线进行比较时，我们发现Ku 80 −/−细胞的热辐射增敏作用并未降低，但实际上有所增加。因此，我们的研究结果表明Ku 80对于热辐射增敏不是必需的。通过比较DNA连接酶IV缺陷型和WT人细胞之间的克隆形成存活率，证实了Ku依赖性或Ku非依赖性NHEJ途径不参与热辐射增敏。因此，我们的数据表明同源重组抑制了辐射诱导的DSB的修复，并作为热辐射增敏的靶点。J.细胞。196：557-564，2003。© 2003 Wiley利斯公司
A synergistic increase in cell killing is observed when a heat‐shock is administered prior to, during, or immediately after exposure to ionizing radiation (IR). This phenomenon, known as heat‐radiosensitization, is believed to be mediated by inhibition of repair of radiation‐induced double strand breaks (DSB) when cells are exposed to temperatures above 42°C. However, the mechanism by which heat inhibits DSB repair is unclear. The bulk of radiation‐induced DSBs are repaired via the non‐homologous end‐joining pathway (NHEJ). Several reports indicate that the Ku70 and Ku80 subunits of the mammalian DNA‐dependent protein kinase (DNA‐PK), a complex involved in NHEJ, appear to be susceptible to a heat‐induced loss of DNA‐binding activity, with Ku80 representing the heat‐sensitive component. Since the heat‐induced loss and subsequent recovery of Ku–DNA binding activity correlates well with heat‐radiosensitization, a role for Ku80 and NHEJ in heat‐radiosensitization has been proposed. However, direct evidence implicating Ku80 (and NHEJ) in heat‐radiosensitization has been indeterminate. In this study, we demonstrate that equitoxic heat treatments at 42.5–45.5°C induce a similar amount of aggregation of Ku80 in human U‐1 melanoma cells. These data suggest that the time–temperature‐dependent relationship between heat lethality and Ku80 aggregation are similar. However, the aggregation/disaggregation of Ku80 and its transient or permanent inactivation is unrelated to heat‐radiosensitization. When survival curves were obtained for irradiated or irradiated and heated Ku80−/− mouse embryo fibroblasts (MEFs) and compared with survival curves obtained for wild‐type (WT) cells, we found that heat‐radiosensitization was not reduced in the Ku80−/− cells, but actually increased. Thus, our findings indicate that Ku80 is not essential for heat‐radiosensitization. Non‐involvement of Ku‐dependent or Ku‐independent NHEJ pathways in heat‐radiosensitization was confirmed by comparing clonogenic survival between DNA ligase IV‐defective and WT human cells. Our data therefore implicate homologous recombination in inhibition of repair of radiation‐induced DSBs and as a target for heat‐radiosensitization. J. Cell. Physiol. 196: 557–564, 2003. © 2003 Wiley‐Liss, Inc.
登录
查看更多内容
加热的 CHO 细胞 DNA 中辐射诱导的双链断裂持续存在。
影响因子：
2.6
作者：
Warters,RL
通讯作者：
Warters,RL
热疗引起的核蛋白含量增加与HeLa S3细胞杀伤的关系。
影响因子：
3.4
作者：
Kampinga,HH;Turkel-Uygur,N;RotiRoti,JL;Konings,AW
通讯作者：
Konings,AW
DOI：
10.1073/pnas.94.25.13588
发表时间：
1997-12-09
影响因子：
11.1
作者：
Nussenzweig, A;Sokol, K;Li, GC
通讯作者：
Li, GC
DOI：
10.1615/critreveukargeneexpr.v7.i4.30
发表时间：
1997
影响因子：
1.6
作者：
J. R. Roti Roti-J.-R.-Roti-Roti-7707447;W. D. Wright;R. Vanderwaal
通讯作者：
J. R. Roti Roti-J.-R.-Roti-Roti-7707447;W. D. Wright;R. Vanderwaal
影响因子：
3.4
作者：
Dewey,WC
通讯作者：
Dewey,WC