Agharkar Research Institute, Nanobioscience Group, G. G. Agarkar Road, Pune 411004, India; Savitribai Phule Pune University, Ganeshkhind, Pune 411 007, India.
Agharkar Research Institute, Nanobioscience Group, G. G. Agarkar Road, Pune 411004, India; Savitribai Phule Pune University, Ganeshkhind, Pune 411 007, India.
J Mol Biol. 2020 Mar 27;432(7):2369-2387. doi: 10.1016/j.jmb.2020.02.025. Epub 2020 Feb 28.
Coordinated assembly of viral and host factors is essential for the successful propagation of viruses as well as the generation of host antiviral response. Previous studies from our group, as well as from other groups, have identified host proteins interacting with various components of the hepatitis E virus (HEV). However, the functional relevance of host protein interactions in HEV replication context has been notably overlooked. The present study reports that heterogeneous nuclear ribonucleoproteins (hnRNPs), namely hnRNPK, hnRNPA2B1, hnRNPH, PCBP1 and PCBP2, interact with HEV RNA promoter and RNA-dependent RNA polymerase to regulate HEV replication. We found that hnRNPK and hnRNPA2B1 are the virus-supportive factors interacting with HEV RNA at promoter regions along with HEV polymerase protein, which are essential for HEV replication in the cells. Contrarily, hnRNPH, PCBP1 and PCBP2 are the antiviral factors that interact exclusively with HEV genomic promoter and inhibit HEV replication in Huh7 S10-3 cells. In vitro RNA-binding assays revealed that the antiviral hnRNP proteins hamper the binding of virus-supportive hnRNP proteins at HEV genomic promoter. In the binding reaction, the binding of HEV polymerase protein to the genomic promoter is slightly affected by the presence of antiviral hnRNPH. In an effort of visualizing the subcellular localization of hnRNP proteins in the HEV replication scenario in the Huh7 cells, we showed that hnRNPK, hnRNPA2B1, hnRNPH, PCBP1 and PCBP2 redistribute from nucleus to cytoplasm. In conclusion, our study highlights the importance of hnRNP proteins in HEV replication regulation.
病毒和宿主因子的协调组装对于病毒的成功繁殖以及宿主抗病毒反应的产生都是至关重要的。我们小组以及其他小组的先前研究已经鉴定出与戊型肝炎病毒 (HEV) 的各种成分相互作用的宿主蛋白。然而，宿主蛋白相互作用在 HEV 复制背景下的功能相关性却明显被忽视了。本研究报告称，异质核核糖核蛋白 (hnRNP)，即 hnRNPK、hnRNPA2B1、hnRNPH、PCBP1 和 PCBP2，与 HEV RNA 启动子和 RNA 依赖性 RNA 聚合酶相互作用，以调节 HEV 复制。我们发现 hnRNPK 和 hnRNPA2B1 是与 HEV RNA 在启动子区域相互作用的病毒支持因子，与 HEV 聚合酶蛋白一起，对于细胞中的 HEV 复制是必不可少的。相反，hnRNPH、PCBP1 和 PCBP2 是抗病毒因子，它们仅与 HEV 基因组启动子相互作用并抑制 Huh7 S10-3 细胞中的 HEV 复制。体外 RNA 结合实验表明，抗病毒 hnRNP 蛋白阻碍病毒支持性 hnRNP 蛋白在 HEV 基因组启动子上的结合。在结合反应中，HEV 聚合酶蛋白与基因组启动子的结合稍微受到抗病毒 hnRNPH 的存在的影响。为了在 Huh7 细胞中观察 HEV 复制情况下 hnRNP 蛋白的亚细胞定位，我们表明 hnRNPK、hnRNPA2B1、hnRNPH、PCBP1 和 PCBP2 从核重新分布到细胞质。总之，我们的研究强调了 hnRNP 蛋白在 HEV 复制调控中的重要性。
