Porcine epidemic diarrhea virus influences the expression of tight junction proteins through the polarity protein PAR6.

Porcine epidemic diarrhea virus (PEDV) is recognized as the primary pathogen causing porcine diarrhea worldwide. For the health of the intestinal mucosa, tight junction proteins are essential. Nevertheless, little is known about the precise processes by which PEDV influences tight junction proteins in epithelial cells. This study aims to investigate the effects of porcine epidemic diarrhea virus (PEDV) infection on the expression of the polarity protein Par6 in IPEC-J2 cells, and to determine whether it influences the expression of tight junction and actin proteins by regulating PAR6. RT-qPCR was used to detect the expression levels of PAR6 and PATJ mRNA. Western blotting and immunofluorescence techniques were used to analyze PAR6 protein expression and localization. Results showed that compared to the control group, PAR6 expression was upregulated and accompanied by abnormal intracellular localization. Subsequently, siRNA-PAR6 and PAR6 overexpression plasmids were constructed. Their effects on tight junction proteins (ZO-1, ZO-2, ZO-3, Occludin, Claudin-1, Claudin-3) and F-actin were evaluated via qPCR and Western blotting. The results demonstrated that, following PEDV infection, PAR6 overexpression and PAR6 knockdown exerted opposite effects on the regulation of the three genes ZO-3, Claudin-1, and Occludin. In summary, PEDV modulates the expression of tight junction proteins (ZO-3, Claudin-1, and Occludin) by regulating the polarity molecule PAR6. This finding deepens our understanding of PEDV pathogenesis and facilitates the development of more effective therapeutics.