RNA binding protein 24 regulates the translation and replication of hepatitis C virus

Huang Cao,Jing Guo,Yun Wang,Yongxuan Yao,Xue Hu,Mengji Lu,Xinwen Chen,Min Guo,Yuan Zhou,Kaitao Zhao,Qi Yang,Rongjuan Pei,Xiaoxiao Gao,Jizheng Chen,Chunchen Wu,Wandi Zhu

doi:10.1007/s13238-018-0507-x

Abstract

The secondary structures of hepatitis C virus (HCV) RNA and the cellular proteins that bind to them are important for modulating both translation and RNA replication. However, the sets of RNA-binding proteins involved in the regulation of HCV translation, replication and encapsidation remain unknown. Here, we identified RNA binding motif protein 24 (RBM24) as a host factor participated in HCV translation and replication. Knockdown of RBM24 reduced HCV propagation in Huh7.5.1 cells. An enhanced translation and delayed RNA synthesis during the early phase of infection was observed in RBM24 silencing cells. However, both overexpression of RBM24 and recombinant human RBM24 protein suppressed HCV IRES-mediated translation. Further analysis revealed that the assembly of the 80S ribosome on the HCV IRES was interrupted by RBM24 protein through binding to the 5′-UTR. RBM24 could also interact with HCV Core and enhance the interaction of Core and 5′-UTR, which suppresses the expression of HCV. Moreover, RBM24 enhanced the interaction between the 5′- and 3′-UTRs in the HCV genome, which probably explained its requirement in HCV genome replication. Therefore, RBM24 is a novel host factor involved in HCV replication and may function at the switch from translation to replication.

Highlights

The genome of hepatitis C virus (HCV) is composed of a single open reading frame (ORF) flanked by 5′- and 3′untranslated regions (UTRs)
Several host factors with RNA-binding domains have been previously reported to be involved in the control of HCV translation and/or replication
Huh7.5.1 cells were transfected with siRNAs, including nonspecific siNC, siRBM24 targeting exon 2 of RNA binding motif protein 24 (RBM24) and siHCV targeting the HCV internal ribosome entry site (IRES), and were infected with Jc1. siHCV successfully restricted HCV replication, and it inhibited the up-regulation of RBM24, further confirming that RBM24 expression was elevated by HCV infection (Fig. 1E and 1F). siRBM24 efficiently decreased the mRNA level of RBM24 (Fig. 1E) without significantly influencing cell viability

Summary

Introduction

The genome of hepatitis C virus (HCV) is composed of a single open reading frame (ORF) flanked by 5′- and 3′untranslated regions (UTRs). The same RNA cannot serve as template for both processes simultaneously because translation proceeds in the 5′ to 3′ direction, whereas negative-strand RNA synthesis occurs in the 3′ to 5′ direction (Shi and Lai, 2006). The 5′- and 3′-UTRs are the most conserved regions of HCV RNA among the different genotypes and isolates. Both of these regions form complex secondary structures with multiple stem-loops and are involved in the control of translation and RNA replication (Shi and Lai, 2006). The core domain of IRES (domains II to IV of the 5′-UTR) directly binds the 40S subunit.

Methods

Results

Conclusion