TGEV infection up-regulates FcRn expression via activation of NF-κB signaling

Abstract

It has been well characterized that the neonatal Fc receptor (FcRn) transports maternal IgG to a fetus or newborn and protects IgG from degradation. We previously reported that FcRn is expressed in a model of normal porcine intestinal epithelial cells (IPEC-J2). Transmissible gastroenteritis is an acute enteric disease of swine that is caused by transmissible gastroenteritis virus (TGEV). How porcine FcRn (pFcRn) expression is regulated by pathogenic infection remains unknown. Our research shows that IPEC-J2 cells infected with TGEV had up-regulated pFcRn expression. In addition, the NF-κB signaling pathway was activated in IPEC-J2 cells by TGEV infection. Furthermore, treatment of TGEV-infected IPEC-J2 cells with the NF-κB-specific inhibitor BAY 11-7082 resulted in down-regulation of pFcRn expression. Transient transfection of pFcRn promoter luciferase report plasmids with overexpression of NF-κB p65 transcription factor enhanced the activation of the luciferase report plasmids. We identified four NF-κB transcription factor binding sites in the promoter region of this gene using luciferase reporter system, chromatin immunoprecipitation, electromobility shift assay, and supershift analysis. Together, the data provide the first evidence that TGEV infection up-regulates pFcRn expression via activation of NF-κB signaling.

Identification and analysis of long non-coding RNAs that are involved in inflammatory process in response to transmissible gastroenteritis virus infection

“…In our data, many neighbouring genes correspond to compartments of the inflammatory response, such as PML (ENSSSCT00000002141), Interferon Beta 1 (IFNB1) (ENSSSCT00000005691), Radical S-Adenosyl methionine domain containing 2 (RSAD2) (ENSSSCT00000009461), and interferon induced protein with tetratricopeptide repeats 5 (IFIT5) (ENSSSCT00000011440). Previous studies have shown that NF-κB signaling pathway, one of the most important pathways, plays an important role during TGEVinduced inflammatory response [9,16,39,40]. Therefore, changes in the expression levels of genes, which related in NF-κB signaling pathway, might influence the TGEV-induced inflammatory response.…”

Transmissible Gastroenteritis Virus Infection Up-Regulates FcRn Expression via Nucleocapsid Protein and Secretion of TGF-β in Porcine Intestinal Epithelial Cells

“…Luciferase reporter plasmids FcRn-Luc, NF-κB-Luc, pR-TK, p65-EGFP, and p65-Tag2B were prepared in our laboratory and have been described previously. Genes encoding TGEV proteins were amplified from the genomic RNA of the TGEV strain WH-1 and then cloned into the expression vector pCAGGS-HA (Guo et al, 2016b) (Table 1). pCAGGS-N was used as a template to amplify several deletion mutants of the virus N gene.…”

“…Proteins were separated via SDS-PAGE and then electrotransferred onto a polyvinylidene difluoride membrane (Bio-Rad, United States). Western blot analysis was performed using the indicated antibodies following the procedure as described previously (Guo et al, 2016b). IPEC-J2 cells grown in a six-well plate were infected with TGEV, the supernatant of IPEC-J2 cells was harvested, and IL-1β, IL-6, IL-8, TGF-β, and TNF-α protein levels were measured with a Quantibody Porcine Cytokine Array 1 (Ray Biotech, Norcross, GA, United States) according to the manufacturer's instructions.…”

“…Most studies on FcRn have focused on the function of FcRn in humans and mice; so far, only a few relevant studies about pathogenic infection and FcRn expression regulation have been reported. In our previous study, TGEV induced FcRn expression via the NF-κB pathway in IPEC-J2 cells (Guo et al, 2016b), but the regulatory mechanisms underlying this remain unclear; thus, we need to further explore the involvement of pattern recognition receptors (PRRs), inflammatory factors, and virus-coding proteins in the regulation of FcRn.…”

Porcine transmissible gastroenteritis virus nonstructural protein 2 contributes to inflammation via NF-κB activation

“…Severe gastroenteritis is a significant clinical sign of TGEV infection, and it is now well-established that NF-κB is a key regulator of inflammation because of its ability to induce the transcription of pro-inflammatory genes such as tumor necrosis factor α (TNF-α), interleukin (IL) −1β, IL-6, and IL-8 [14,15]. In the current study, we found that TGEV infection induced the inflammatory response through NF-κB signal activation, but that NF-κB inhibition did not significantly affect TGEV replication.…”