The DDX23 Negatively Regulates Translation and Replication of Foot-and-Mouth Disease Virus and Is Degraded by 3C Proteinase

Abstract

DEAD-box helicase 23 (DDX23) is a host nuclear helicase, which is a part of the spliceosomal complex and involved in pre-mRNA splicing. To investigate whether DDX23, an internal ribosomal entry sites transacting factor (ITAF) affects foot-and-mouth disease virus (FMDV) replication and translation through internal ribosome entry site (IRES)-dependent manner. For this, we utilized a pull-down assay, Western blotting, quantitative real-time PCR, confocal microscopy, overexpression and small interfering RNA knockdown, as well as the median tissue culture infective dose. Our findings showed that FMDV infection inhibited DDX23 expression and the overexpression of DDX23 reduced viral replication, however, CRISPR Cas9 knockout/small interfering RNA knockdown increased FMDV replication. FMDV IRES domain III and IV interacted with DDX23, whereas DDX23 interacted with FMDV 3C proteinase and significantly degraded. The enzymatic activity of FMDV 3C proteinase degraded DDX23, whereas FMDV degraded DDX23 via the lysosomal pathway. Additionally, IRES-driven translation was suppressed in DDX23-overexpressing cells, and was enhanced in DDX23 knocked down. Collectively, our results demonstrated that DDX23 negatively affects FMDV IRES-dependent translation, which could be a useful target for the design of antiviral drugs.

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

“…Similarly, the crucial FMDV protease 3C pro participates in the frontline defense of the virus to maintain viral integrity by inhibiting the host IFN response [ 58 ]. Our previous study confirmed that FMDV 3C pro degrades DDX23 to antagonize its antiviral activity [ 35 ].…”

“…Target proteins were pulled down using the Pierce Magnetic RNA-Protein Pull-Down Kit (Thermo Scientific Pierce, Rockford, IL, USA) following the manufacturer’s instructions. The experiments were performed as described in detail previously [ 35 ].…”

“…Foot-and-mouth disease virus (FMDV) contains a type II IRES [ 25 ], which is comprised of five domains, of which domains 2 to 5 are crucial for viral IRES-dependent translation (Figure 1a) [ 26 , 27 , 28 , 29 ]. Cellular ITAFs have been reported to interact with the FMDV IRES to promote or inhibit viral replication; for example, DDX3, Rab1b, Sam68, PTB, and ITAF45 [ 17 , 18 , 30 , 31 ] promote FMDV IRES translation, whereas Gemin5, G3BP1, hnRNP K, hnRNP L, DDX1, and DDX23 [ 26 , 32 , 33 , 34 , 35 , 36 ] inhibit FMDV viral translation.…”

“…During influenza virus infection, DDX21 promotes the expression of S100A9, which is responsible for the induction of inflammatory and innate immune responses thorough the TLR4/MyD88 pathway against influenza A virus infection [ 50 ]. Recently, the other members of the DEAD-box family, including DDX1, DDX56, DDX3, and DDX23 [ 35 , 36 , 51 , 52 ], have also been reported, highlighting their immense significance in the IRES-dependent translation of FMDV.…”

Sec62 Regulates Endoplasmic Reticulum Stress and Autophagy Balance to Affect Foot-and-Mouth Disease Virus Replication

“…FMDV is the most economically important and highly contagious veterinary pathogen, affecting long-term livestock health and international trade ( Grubman and Baxt, 2004 ; Dong et al., 2021 ). Although the outbreaks of FMD have been effectively controlled by various prophylactic vaccines and animal culling ( Jamal and Belsham, 2013 ; Abdullah et al., 2020 ), the potential for future outbreaks warns us of the need for safe and effective therapeutics to prevent viral infections. Growing researches have demonstrated that many viruses can induce endoplasmic reticulum (ER) stress-mediated autophagy to regulate viral replication and pathogenesis ( Lv et al., 2015 ; Sharma et al., 2017 ; Lee et al., 2018 ).…”