Porcine Epidemic Diarrhea Virus Inhibits HDAC1 Expression To Facilitate Its Replication via Binding of Its Nucleocapsid Protein to Host Transcription Factor Sp1

Abstract

Porcine epidemic diarrhea virus (PEDV) is an enteric coronavirus causing acute intestinal infection in pigs, with high mortality often seen in neonatal pigs. The newborns rely on innate immune responses against invading pathogens because of lacking adaptive immunity. However, how PEDV disables the innate immunity of newborns towards severe infection remains unknown. We found that PEDV infection led to reduced expression of histone deacetylases (HDACs), especially HDAC1 in porcine IPEC-J2 cells. HDACs are considered as important regulators of innate immunity. We hypothesized that PEDV might interact with certain host factors to regulate HDAC1 expression in favor of its replication. We show that HDAC1 acted as a negative regulator of PEDV replication in IPEC-J2 cells, as shown by chemical inhibition, gene knockout and overexpression. A GC-box ( GCCCCACCCCC ) within the HDAC1 promoter region was identified for Sp1 binding in IPEC-J2 cells. Treatment of the cells with Sp1 inhibitor, mithramycin A, inhibited HDAC1 expression, indicating direct regulation of HDAC1 expression by Sp1. Of the viral proteins that were overexpressed in IPEC-J2 cells, the N protein was found to be present in the nuclei and more inhibitory to HDAC1 transcription. The putative NLS 261 PKKNKSR 267 contributed to its nuclear localization. The N protein interacted with Sp1 and interfered with its binding to the promoter region, thereby inhibiting its transcriptional activity for HDAC1 expression. Our findings reveal a novel mechanism of PEDV evasion of the host responses, offering implications for studying the infection processes of other coronaviruses. Importance The enteric coronavirus porcine epidemic diarrhea virus (PEDV) causes fatal acute intestinal infection in neonatal pigs that rely on innate immune responses. Histone deacetylases (HDACs) play important roles in innate immune regulation. Our study found PEDV suppresses HDAC1 expression via the interaction of its N protein and porcine Sp1, which identified a novel mechanism of PEDV evasion of the host responses to benefit its replication. This study suggests that other coronaviruses, including SARS-CoV and SARS-CoV-2, may also make use of their N proteins to intercept the host immune responses in favor of their infection.

The Network of Interactions between the Porcine Epidemic Diarrhea Virus Nucleocapsid and Host Cellular Proteins

“…Previous studies have reported 11 of the host interacting proteins with PEDV N by other approaches [ 13 , 14 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Among these 11 proteins, only 3 proteins, namely TRIM21, nucleophosmin-1 (NPM1), and poly(A)-binding protein 4 (PABPC4) were confirmed in the present study.…”

“…Despite initially serving as a purely structural protein, the nucleocapsid protein of coronavirus is becoming a key regulator of the virus–host cellular interface. To date, there have been several reports on the interaction between cellular proteins and the PEDV N protein, as shown by co-immunoprecipitation assays [ 13 , 14 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. However, the broad and accurate interaction profile between PEDV N and cellular proteins still remains unknown.…”

The CREB and AP-1–Dependent Cell Communication Network Factor 1 Regulates Porcine Epidemic Diarrhea Virus-Induced Cell Apoptosis Inhibiting Virus Replication Through the p53 Pathway

“…Porcine epidemic diarrhea virus evolved a variety of strategies to promote its persistent infection in the host cell ( Li et al, 2021 ; Su et al, 2021 ; Xu et al, 2021 ). To escape the invasion of the virus, the secretion of antiviral proteins in the host cell was enhanced ( Li et al, 2019 ; Pandey et al, 2019 ; Wang et al, 2021 ).…”

DNAJA3 Interacts with PEDV S1 Protein and Inhibits Virus Replication by Affecting Virus Adsorption to Host Cells

“…Zhang et al demonstrated that DNAJA3 interacted with the VP1 of the food-and-mouth virus and inhibited viral replication by inducing lysosomal degradation of VP1 and weakening its antagonistic effect in the interferon β signaling pathway [37]. HSP40 has been reported to interact with the 3 end of RNA of the murine hepatitis virus to possibly promote its stability [45]. However, there is a paucity of information on the role of Hsp40 family members in other coronaviruses.…”