Investigation of the regulatory mechanisms of translesion synthesis by DNA polymerase η, the XPV gene product.

人类DNA聚合酶η是XPV基因产物，它是一种易患癌症的遗传疾病——色素干酪皮变异体的罪魁祸首。我们对1999年发现的DNA聚合酶η感兴趣。DNA聚合酶η是一种新型的DNA聚合酶，它能准确地催化环丁烷嘧啶二聚体的翻译合成，而环丁烷嘧啶二聚体是紫外线照射引起的主要DNA损伤。由于经典的复制性DNA聚合酶α、δ和ε不能催化TLS通过病变，因此DNA聚合酶η在含有病变的DNA复制中起重要作用。目前对DNA聚合酶η的调控机制知之甚少。在这里，我们研究了DNA聚合酶η相互作用蛋白。通过酵母双杂交系统、重组蛋白拉下分析和真核细胞共表达实验，我们发现DNA聚合酶η与Rev1和PCNA相互作用。Rev1是一种参与易出错翻译合成的脱氧胞二转移酶。PCNA是复制NA聚合酶δ和ε的滑动夹。因此，这些相互作用可能有助于不同病变部位的DNA聚合酶转换和/或DNA聚合酶选择。在此基础上，人类细胞中翻译合成的机制将在不久的将来得到阐明。

Human DNA polymerase η is the XPV gene product which is responsible for a cancer-prone genetic disease, keroderma pigmentosum variant. We are interested in DNA polymerase η which we have identified in 1,999. DNA polymerase η is a novel type of DNA polymerase and catalyzes translesion snthesis across cyclobutane pyrimidine dimers, the major DNA lesions induced by UV-irradiation, in an accurate manner. Since classical replicative DNA polymerases α, δ, and ε can not catalyze TLS past the lesions, DNA polyrnerase η plays an important role in the replication of DNA containing lesions. Little is known concerning the regulatory mechanisms of DNA polymerase η. Here we investigated DNA polymerase η-interacting proteins.Using yeast two-hybrid systems, pull-down analyses with recombinant proteins, and co-expression experiments in eukaryotic cells, we found that DNA polymerase η interacts with Rev1 and PCNA. Rev1 is a deoxycytidiltransferase involved in the error-prone translesion synthesis. PCNA is a sliding clamp of replicative NA polymerases δ and ε. So, these interactions may contribute to the DNA polymerase switching and/or DNA polymerase selection at various lesion sites. Based on the results, mechanisms for translesion synthesis in human cells will be clarified in near future.