Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada.
Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada
J Virol. 2018 Jun 29;92(14). doi: 10.1128/JVI.00439-18. Print 2018 Jul 15.
Far-upstream element (FUSE) binding protein 1 (FUBP1) was originally identified as a regulator of the oncogene via binding to the FUSE within the promoter and activating the expression of the gene. Recent studies have identified FUBP1 as a regulator of transcription, translation, and splicing via its DNA and RNA binding activities. Here we report the identification of FUBP1 as a novel binding partner of E1A. FUBP1 binds directly to E1A via the N terminus (residues 1 to 82) and conserved region 3 (residues 139 to 204) of adenovirus 5 E1A. The depletion of FUBP1 via short interfering RNAs (siRNA) reduces virus growth and drives the upregulation of the cellular stress response by activating the expression of p53-regulated genes. During infection, FUBP1 is relocalized within the nucleus, and it is recruited to viral promoters together with E1A while at the same time being lost from the FUSE upstream of the promoter. The depletion of FUBP1 affects viral and cellular gene expression. Importantly, in FUBP1-depleted cells, p53-responsive genes are upregulated, p53 occupancy on target promoters is enhanced, and histone H3 lysine 9 is hyperacetylated. This is likely due to the loss of the FUBP1-mediated suppression of p53 DNA binding. We also observed that E1A stabilizes the FUBP1-p53 complex, preventing p53 promoter binding. Together, our results identify, for the first time, FUBP1 as a novel E1A binding protein that participates in aspects of viral replication and is involved in the E1A-mediated suppression of p53 function. Viral infection triggers innate cellular defense mechanisms that have evolved to block virus replication. To overcome this, viruses have counterevolved mechanisms that ensure that cellular defenses are either disarmed or not activated to guarantee successful replication. One of the key regulators of cellular stress is the tumor suppressor p53 that responds to a variety of cellular stress stimuli and safeguards the integrity of the genome. During infection, many viruses target the p53 pathway in order to deactivate it. Here we report that human adenovirus 5 coopts the cellular protein FUBP1 to prevent the activation of the p53 stress response pathway that would block viral replication. This finding adds to our understanding of p53 deactivation by adenovirus and highlights its importance in infection and innate immunity.
远上游元件结合蛋白 1（FUBP1）最初被鉴定为通过与启动子中的 FUSE 结合来调节癌基因，从而激活基因的表达。最近的研究表明，FUBP1 通过其 DNA 和 RNA 结合活性，作为转录、翻译和剪接的调节剂。在这里，我们报告了 FUBP1 作为新型 E1A 结合蛋白的鉴定。FUBP1 通过腺病毒 5 E1A 的 N 端（残基 1 至 82）和保守区 3（残基 139 至 204）直接与 E1A 结合。通过短发夹 RNA（siRNA）耗尽 FUBP1 会降低病毒生长，并通过激活 p53 调节基因的表达来驱动细胞应激反应的上调。在感染过程中，FUBP1 在核内重新定位，与 E1A 一起被募集到病毒启动子，同时从 启动子的 FUSE 上游丢失。FUBP1 的耗尽会影响病毒和细胞基因的表达。重要的是，在 FUBP1 耗尽的细胞中，p53 反应基因上调，p53 靶启动子上的结合增强，组蛋白 H3 赖氨酸 9 乙酰化过度。这可能是由于 FUBP1 介导的 p53 DNA 结合抑制的丧失。我们还观察到 E1A 稳定 FUBP1-p53 复合物，防止 p53 启动子结合。总之，我们的研究结果首次鉴定出 FUBP1 是一种新型的 E1A 结合蛋白，它参与病毒复制的各个方面，并参与 E1A 介导的 p53 功能抑制。病毒感染触发了进化而来的先天细胞防御机制，以阻止病毒复制。为了克服这一点，病毒已经进化出了确保细胞防御机制被解除或未被激活以保证成功复制的机制。细胞应激的关键调节因子之一是肿瘤抑制因子 p53，它对多种细胞应激刺激做出反应，保护基因组的完整性。在感染过程中，许多病毒靶向 p53 途径以使其失活。在这里，我们报告人类腺病毒 5 利用细胞蛋白 FUBP1 来阻止激活 p53 应激反应途径，从而阻止病毒复制。这一发现增加了我们对腺病毒 p53 失活的理解，并强调了其在感染和先天免疫中的重要性。
