Charp P A, Regan J D
Biochim Biophys Acta. 1985 Jan 29;824(1):34-9. doi: 10.1016/0167-4781(85)90026-0.
We examined the possible role of calmodulin in the excision repair of ultraviolet light-induced pyrimidine dimers in damaged DNA by means of specialized assay systems. These assays included bromodeoxyuridine photolysis, dimer chromatography and cytosine arabinoside incorporation in conjunction with hydroxyurea. The calmodulin antagonist, trifluoperazine, and the calcium-chelating agent, EGTA, were employed to ascertain what affect calmodulin played in the repair process. Normal human fibroblast cells were used in all studies described in this report. After exposure to 10 J/m2 of 254 nm light, we observed a decrease of about 30% in the number of single-strand breaks produced in the presence of 25 microM trifluoperazine (1.9 vs. 3.3) in controls although the numbers of bases re-inserted in the repaired regions were similar (64 vs. 72). Measurement of thymine-containing dimers remaining throughout a 24 h time period indicated a 30% difference in the excision of dimers when tested with either EGTA or trifluoperazine. We also observed a significant decrease in the number of cytosine arabinoside arrested repair sites in the presence of either EGTA or trifluoperazine. The results are discussed with relation to the possibility of calmodulin altering the initial incision by repair endonuclease.
我们借助专门的检测系统，研究了钙调蛋白在紫外线诱导的受损DNA中嘧啶二聚体切除修复过程中可能发挥的作用。这些检测包括溴脱氧尿苷光解、二聚体色谱分析以及结合羟基脲的阿糖胞苷掺入实验。使用钙调蛋白拮抗剂三氟拉嗪和钙螯合剂乙二醇双四乙酸（EGTA）来确定钙调蛋白在修复过程中所起的作用。本报告中描述的所有研究均使用正常人成纤维细胞。在暴露于10 J/m²的254 nm光后，我们观察到，在存在25 microM三氟拉嗪的情况下，对照组中产生的单链断裂数量减少了约30%（1.9对3.3），尽管修复区域中重新插入的碱基数量相似（64对72）。对整个24小时时间段内残留的含胸腺嘧啶二聚体进行测量表明，在用EGTA或三氟拉嗪测试时，二聚体切除率存在30%的差异。我们还观察到，在存在EGTA或三氟拉嗪的情况下，阿糖胞苷阻止修复位点的数量显著减少。结合钙调蛋白改变修复内切酶初始切口的可能性对结果进行了讨论。
