Miura M, Domon M, Sasaki T, Takasaki Y
Department of Dental Radiology and Radiation Research, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.
J Cell Physiol. 1992 Feb;150(2):370-6. doi: 10.1002/jcp.1041500221.
Accumulated evidence indicates that proliferating cell nuclear antigen (PCNA) is an auxiliary protein of DNA polymerase delta and forms tight association with DNA replication sites during DNA replication or DNA repair synthesis. In this study, such PCNA complex formation was investigated by the indirect immunofluorescence method, using both normal human fibroblasts and those derived from a xeroderma pigmentosum group A (XP-A) patient. XP-A fibroblasts in both proliferating and quiescent states did not show any differences from normal fibroblasts in the properties of PCNA-staining in the untreated conditions. The PCNA complex formation was induced in quiescent normal fibroblasts by both ultraviolet light (UV)- and X-irradiation, whereas in XP-A fibroblasts it was induced by X-irradiation, but not by UV-irradiation. However, PCNA complex was induced in quiescent XP-A fibroblasts by UV-irradiation when the cells had previously incorporated 5-bromodeoxyuridine (BrdU). These observations indicate a close correlation of PCNA complex formation and unscheduled DNA synthesis (UDS). Thus, it was concluded that PCNA complex formation was commonly induced in at least three conditions to produce UDS in spite of different types of DNA damages and DNA repair mechanisms.
越来越多的证据表明，增殖细胞核抗原（PCNA）是DNA聚合酶δ的辅助蛋白，在DNA复制或DNA修复合成过程中与DNA复制位点紧密结合。在本研究中，采用间接免疫荧光法，利用正常人成纤维细胞和来自A型着色性干皮病（XP - A）患者的成纤维细胞，对这种PCNA复合物的形成进行了研究。处于增殖和静止状态的XP - A成纤维细胞在未处理条件下的PCNA染色特性与正常成纤维细胞没有任何差异。静止的正常成纤维细胞经紫外线（UV）和X射线照射均可诱导PCNA复合物的形成，而XP - A成纤维细胞经X射线照射可诱导形成，经UV照射则不能。然而，当静止的XP - A成纤维细胞预先掺入5 - 溴脱氧尿苷（BrdU）时，经UV照射可诱导形成PCNA复合物。这些观察结果表明PCNA复合物的形成与DNA的非预定合成（UDS）密切相关。因此，得出的结论是，尽管DNA损伤类型和DNA修复机制不同，但在至少三种条件下通常会诱导PCNA复合物的形成以产生UDS。
