Porcine IGFBP3 promotes porcine circovirus type 2 replication via PERK/ eIF2α mediated DNA damage

The infection of porcine circovirus type 2 (PCV2) triggers activation of the protein kinase RNA-like endoplasmic reticulum kinase (PERK) pathway and leads to DNA damage. Insulin-like growth factor-binding protein 3 (IGFBP3) may interact with the endoplasmic reticulum (ER). It remains unclear whether IGFBP3 regulates DNA damage via ER stress to mediate PCV2 replication. In this study, we observed an upregulation of porcine IGFBP3 expression during PCV2 infection, and overexpression of IGFBP3 enhanced the expression of PCV2 Cap protein, PCV2 DNA copy number, and viral titers in PK-15 B6 cells and 3D4/21 cells. Additionally, overexpression of IGFBP3 induced an increase in the DNA damage marker gamma H2AX by activating the PERK/eIF2 alpha pathway without concomitant activation of ATF4, IRE1 alpha, and ATF6 alpha/GRP78 pathways in PK-15 B6 cells and 3D4/21 cells. Knockdown of IGFBP3 had a reverse effect on PCV2 replication in PK-15 B6 cells and 3D4/21 cells. Furthermore, treatment with etoposide enhanced PCV2 replication while KU57788 decreased it. GSK2606414 and salubrinal limited both DNA damage and viral replication. Therefore, our findings suggest that porcine IGFBP3 promotes PCV2 replication through the PERK/eIF2 alpha pathway-mediated induction of DNA damage in PK-15 B6 cells and 3D4/21 cells. Our study provides a basis for exploring novel antiviral strategies via the extensive understanding of the relationships between host cellular proteins and viral replication.

Automated summary

The infection of porcine circovirus type 2 (PCV2) triggers the activation of the PERK pathway and leads to DNA damage. This study reveals that IGFBP3 may regulate DNA damage via ER stress to mediate PCV2 replication. The overexpression of IGFBP3 enhances PCV2 replication by activating the PERK/eIF2 alpha pathway-mediated induction of DNA damage. Targeting this pathway could be a potential antiviral strategy.