Wawra E, Zollner H, Schaur R J, Tillian H M, Schauenstein E
Cell Biochem Funct. 1986 Jan;4(1):31-6. doi: 10.1002/cbf.290040105.
The purpose of this study was to determine firstly whether the isolated enzyme DNA polymerase alpha, which functions within the DNA replicase system, exhibits different sensitivity against the thiol-blocking agent 4-hydroxy-nonenal (HNE) when adult rat liver and the rapidly dividing Yoshida ascites hepatoma were used as enzyme sources and, secondly, whether the reaction catalysed by DNA polymerase is the most sensitive step of the DNA replicase system of native cells. DNA polymerase alpha as well as the non-replicative DNA polymerase beta, isolated from both sources, were remarkably similar with regard to their sensitivity against HNE, as indicated by the incorporation of radioactive label from [3H]deoxy-thymidine-triphosphate into DNA. The transport of [14C]thymidine through the plasma membrane and the incorporation of this precursor into DNA were studied with neonatal hepatocytes and with hepatoma cells. The incorporation of thymidine was inhibited at lower concentrations of HNE in both cell lines than the transport process and the reaction catalysed by DNA polymerase alpha. It was concluded that in the DNA replicase system of native liver and hepatoma cells another process different from the reaction catalysed by DNA polymerase alpha is more sensitive to HNE.
本研究的目的，一是确定当以成年大鼠肝脏和快速分裂的吉田腹水肝癌细胞作为酶源时，在DNA复制酶系统中起作用的分离酶DNA聚合酶α对硫醇阻断剂4-羟基壬烯醛（HNE）是否表现出不同的敏感性；二是确定DNA聚合酶催化的反应是否是天然细胞DNA复制酶系统中最敏感的步骤。从这两种来源分离得到的DNA聚合酶α以及非复制性DNA聚合酶β，就其对HNE的敏感性而言非常相似，这一点通过将[3H]脱氧胸苷三磷酸中的放射性标记掺入DNA得以体现。用新生肝细胞和肝癌细胞研究了[14C]胸苷通过质膜的转运以及该前体掺入DNA的情况。在两种细胞系中，胸苷掺入受到抑制时的HNE浓度都低于转运过程和DNA聚合酶α催化的反应。得出的结论是，在天然肝脏和肝癌细胞的DNA复制酶系统中，不同于DNA聚合酶α催化反应的另一个过程对HNE更为敏感。
