Vermeulen Christie, Verwijs-Janssen Manon, Begg Adrian C, Vens Conchita
Division of Experimental Therapy, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
Radiother Oncol. 2008 Mar;86(3):391-8. doi: 10.1016/j.radonc.2008.01.002. Epub 2008 Jan 30.
The purpose of the present study was to determine the role of DNA polymerase beta in repair and response after ionizing radiation in different phases of the cell cycle.
Synchronized cells deficient and proficient in DNA polymerase beta were irradiated in different phases of the cell cycle as determined by BrdU/flow cytometry. Cell kill and DNA repair were assessed by colony formation and alkaline comet assays, respectively.
We first demonstrated delayed repair of ionizing radiation induced DNA damage in confluent polymerase beta deficient cells. Cell synchronization experiments revealed a cell cycle phase dependence by demonstrating radiation hypersensitivity of polymerase beta-deficient cells in G1, but not in the S-phase. Complementing polymerase beta-deficient cells with polymerase beta reverted the hypersensitivity in G1. Ionizing radiation damage repair was found to be delayed in beta-deficient cells when irradiated in G1, but not in S.
The data show a differential role of DNA polymerase beta driven base excision and single strand break repair throughout the cell cycle after ionizing radiation damage.
本研究旨在确定DNA聚合酶β在细胞周期不同阶段电离辐射后的修复及反应中的作用。
通过BrdU/流式细胞术确定细胞周期的不同阶段，对缺乏和具备DNA聚合酶β的同步化细胞进行电离辐射。分别通过集落形成和碱性彗星试验评估细胞杀伤和DNA修复情况。
我们首先证明了在汇合的缺乏聚合酶β的细胞中，电离辐射诱导的DNA损伤修复延迟。细胞同步化实验通过证明缺乏聚合酶β的细胞在G1期而非S期对辐射敏感，揭示了细胞周期阶段依赖性。用聚合酶β补充缺乏聚合酶β的细胞可逆转G1期的敏感性。当在G1期照射时，发现缺乏β的细胞中电离辐射损伤修复延迟，但在S期则不然。
数据表明，在电离辐射损伤后，DNA聚合酶β驱动的碱基切除和单链断裂修复在整个细胞周期中具有不同作用。
