DDX21, a Host Restriction Factor of FMDV IRES-Dependent Translation and Replication.

Sahibzada Waheed Abdullah,Yun Zhang,Manyuan Bai,Shiqi Sun,Jin’En Wu,Junyong Guan,Xiangtao Liu,Huichen Guo

doi:10.3390/v13091765

Abstract

In cells, the contributions of DEAD-box helicases (DDXs), without which cellular life is impossible, are of utmost importance. The extremely diverse roles of the nucleolar helicase DDX21, ranging from fundamental cellular processes such as cell growth, ribosome biogenesis, protein translation, protein–protein interaction, mediating and sensing transcription, and gene regulation to viral manipulation, drew our attention. We designed this project to study virus–host interactions and viral pathogenesis. A pulldown assay was used to investigate the association between foot-and-mouth disease virus (FMDV) and DDX21. Further insight into the DDX21–FMDV interaction was obtained through dual-luciferase, knockdown, overexpression, qPCR, and confocal microscopy assays. Our results highlight the antagonistic feature of DDX21 against FMDV, as it progressively inhibited FMDV internal ribosome entry site (IRES) -dependent translation through association with FMDV IRES domains 2, 3, and 4. To subvert this host helicase antagonism, FMDV degraded DDX21 through its non-structural proteins 2B, 2C, and 3C protease (3Cpro). Our results suggest that DDX21 is degraded during 2B and 2C overexpression and FMDV infection through the caspase pathway; however, DDX21 is degraded through the lysosomal pathway during 3Cpro overexpression. Further investigation showed that DDX21 enhanced interferon-beta and interleukin-8 production to restrict viral replication. Together, our results demonstrate that DDX21 is a novel FMDV IRES trans-acting factor, which negatively regulates FMDV IRES-dependent translation and replication.

Highlights

Protein synthesis in eukaryotes is a normal mechanism to carry on a multitude of cellular processes
footand-mouth disease virus (FMDV) utilizes the indispensable weapon internal ribosome entry site (IRES) to hijack a variety of Viruses must multiply with limited resources, even though a multitude of processe host proteins known as IRES trans-acting factors (ITAFs) to promote translation of the viral mRNA [11]
Studies are required for replication; they depend upon the host to proliferate and flouris have reported new ITAFs that modulate FMDV IRES-mediated translation and replica

Summary

Introduction

Protein synthesis in eukaryotes is a normal mechanism to carry on a multitude of cellular processes. Translation of mRNA is a complex process, which involves initiation, elongation, termination, and ribosome recycling [1]. Cells use the cap-dependent mechanism to translate mRNA, and eukaryotic initiation factors (eIFs), the ternary complex (consisting of eIF2 (α, β, and γ subunits), GTP, and. Met-tRNAi), and Met-tRNAi (a transfer RNA containing the anticodon for methionine, which initiates the translation with the help of other association factors) are recruited onto the 40S subunits to form the 43S pre-initiation complex that attaches to the 50 region of the mRNA [1]. The cap structure protects the RNA from degradation by exonuclease cleavage and is recognized by the eIFs involved in the assembly of the ribosome [3].

Methods

Results

Conclusion