Heat shock protein 70 promotes coxsackievirus B3 translation initiation and elongation via Akt-mTORC1 pathway depending on activation of p70S6K and Cdc2

Abstract

We previously demonstrated that coxsackievirus B3 (CVB3) infection upregulated heat shock protein 70 (Hsp70) and promoted CVB3 multiplication. Here, we report the underlying mechanism by which Hsp70 enhances viral RNA translation. By using an Hsp70-overexpressing cell line infected with CVB3, we found that Hsp70 enhanced CVB3 VP1 translation at two stages. First, Hsp70 induced upregulation of VP1 translation at the initiation stage via upregulation of internal ribosome entry site trans-acting factor lupus autoantigen protein and activation of eIF4E binding protein 1, a cap-dependent translation suppressor. Second, we found that Hsp70 increased CVB3 VP1 translation by enhancing translation elongation. This was mediated by the Akt-mammalian target of rapamycin complex 1 signal cascade, which led to the activation of eukaryotic elongation factor 2 via p70S6K- and cell division cycle protein 2 homolog (Cdc2)-mediated phosphorylation and inactivation of eukaryotic elongation factor 2 kinase. We also determined the position of Cdc2 in this signal pathway, indicating that Cdc2 is regulated by mammalian target of rapamycin complex 1. This signal transduction pathway was validated using a number of specific pharmacological inhibitors, short interfering RNAs (siRNAs) and a dominant negative Akt plasmid. Because Hsp70 is a central component of the cellular network of molecular chaperones enhancing viral replication, these data may provide new strategies to limit this viral infection.

Stress proteins: the biological functions in virus infection, present and challenges for target-based antiviral drug development

“…In the elongation step, Hsp70 activates the Akt-mammalian target of rapamycin complex 1 (mTORC1) signal cascade, leading to activation of EEF2 via kinase p70S6K-and Cdc2-mediated phosphorylation and inactivation of EEF2 kinase (EF2K). 218 Hsc70 enhances the IRES activity in EV-A71 infected cells. Hsc70 interacts with 2A protease of EV-A71 to enhance EIF4G cleavage that impairs host cell cap-dependent translation but enhances viral IRES-mediated translation.…”

“…Virus entry RNA virus: CAV-9, 186 EV-A71, 188 DENV, 110,189 JEV, 191 ZIKV 190,197 DNA virus: SV40, 234 AdV, 237 HSV, 241 polyomavirus 254 RT virus: HTLV-1, 258,259 HIV-1 260 Virus replication RNA virus: MuV, 201 CDV, 203,204 HCV, 206 RSV, 209 EBOV, 212,213 Influenza 217 Virus gene expression RNA virus: Coxsackievirus B3, 218 EV-A71, 219 Influenza A [222][223][224][225][226] DNA virus: Polyomavirus, JCV, HCMV, 245,[246][247][248][249] Assembly RNA virus: Reovirus, 227 Poliovirus, 228 Coxsackievirus B1, 228 Influenza 229 DNA virus: Polyomavirus 254 Virus release RNA virus: HCV 232,233 Cellular transformation DNA virus: SV40, [264][265][266][267]…”

“…In the case of coxsackievirus B3 (CVA B3) infection, Hsp70 is upregulated to enhance the initiation and elongation of viral translation. 218 In the translation initiation step, Hsp70 upregulates IRES-acting factor lupus autoantigen protein expression and activates eIF4E binding protein 1 (EIF4EBP1), a cap-dependent translation suppressor. In the elongation step, Hsp70 activates the Akt-mammalian target of rapamycin complex 1 (mTORC1) signal cascade, leading to activation of EEF2 via kinase p70S6K-and Cdc2-mediated phosphorylation and inactivation of EEF2 kinase (EF2K).…”

The Capsid Protein VP1 of Coxsackievirus B Induces Cell Cycle Arrest by Up-Regulating Heat Shock Protein 70

“…The activation of HSF1 is controlled by phosphorylation. Studies have shown that CVB3 activates calcium/calmodulin-dependent protein kinase II (CaMKII), which phosphorylates HSF1 at serine 230 (Qiu et al, 2016; Wang F. et al, 2017). In this study, we determined the phosphorylation of HSF1 at serine 326, which also promotes the activation of HSF1 (Chou et al, 2012).…”

High expression of ACTL8 is poor prognosis and accelerates cell progression in head and neck squamous cell carcinoma

“…The results indicated that the expression levels of phosphorylated PI3K and AKT were reduced in PCI-13 cells transfected by ACTL8 siRNA. In addition, the downstream action target of the PI3K/AKT signaling pathway, p70S6K, serves a crucial role in translation initiation, cell metastasis, protein synthesis and cell cycle (27,28). Similarly, the expression levels of p70S6 K in the PI3K/AKT signaling pathway were deceased following si-ACTL8 transfection in the present study.…”