Proliferating cell nuclear antigen (PCNA) is a multifunctional protein present in the nuclei of eukaryotic cells that plays an important role as a component of the DNA replication machinery, as well as DNA repair systems. PCNA was recently proposed as a potential non-oncogenic target for anti-cancer therapy. In this study, using the Systematic Evolution of Ligands by EXponential enrichment (SELEX) method, we developed a short DNA aptamer that binds human PCNA. In the presence of PCNA, the anti-PCNA aptamer inhibited the activity of human DNA polymerase δ and ϵ at nM concentrations. Moreover, PCNA protected the anti-PCNA aptamer against the exonucleolytic activity of these DNA polymerases. Investigation of the mechanism of anti-PCNA aptamer-dependent inhibition of DNA replication revealed that the aptamer did not block formation, but was a component of PCNA/DNA polymerase δ or ϵ complexes. Additionally, the anti-PCNA aptamer competed with the primer-template DNA for binding to the PCNA/DNA polymerase δ or ϵ complex. Based on the observations, a model of anti-PCNA aptamer/PCNA complex-dependent inhibition of DNA replication was proposed.

中文翻译：

---

抗PCNA适体/ PCNA复合物抑制DNA复制

增殖细胞核抗原（PCNA）是存在于真核细胞核中的多功能蛋白，在DNA复制机制以及DNA修复系统中起着重要作用。最近提出将PCNA用作抗癌治疗的潜在非致癌靶标。在这项研究中，使用通过指数富集的配体系统进化（SELEX）方法，我们开发了一种结合人PCNA的短DNA适体。在PCNA存在下，抗PCNA适体在nM浓度下抑制人DNA聚合酶δ和the的活性。此外，PCNA保护抗PCNA适体免受这些DNA聚合酶的核酸外切酶活性的影响。对抗PCNA适配子依赖性抑制DNA复制的机制的研究表明，该适配子不会阻止形成，但是PCNA / DNA聚合酶δ或ϵ复合物的组成部分。另外，抗PCNA适体与引物模板DNA竞争结合至PCNA / DNA聚合酶δ或β复合物。基于这些观察，提出了抗PCNA适体/ PCNA复合物依赖性的DNA复制抑制模型。