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

人DNA聚合酶η是XPV基因产物，其导致一种癌症易感性遗传疾病，着色性角皮病变体。我们对1999年鉴定的DNA聚合酶η感兴趣。DNA聚合酶η是一种新型的DNA聚合酶，能准确地催化环丁烷嘧啶二聚体的跨损伤合成。由于经典的复制型DNA聚合酶α、δ和ε不能催化TLS通过损伤，因此DNA聚合酶η在含损伤的DNA的复制中起重要作用。关于DNA聚合酶η的调节机制知之甚少。本研究利用酵母双杂交系统、重组蛋白pull-down分析和真核细胞共表达实验，研究了DNA聚合酶η与Rev 1和PCNA的相互作用。Rev 1是一种参与易错跨损伤合成的脱氧胞苷转移酶。PCNA是复制型NA聚合酶δ和ε的滑动夹。因此，这些相互作用可能有助于DNA聚合酶转换和/或DNA聚合酶选择在不同的病变部位。基于这些结果，在不久的将来，人类细胞中跨损伤合成的机制将被阐明。

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.