Porcine epidemic diarrhea virus ORF3 protein causes endoplasmic reticulum stress to facilitate autophagy

• Published in: Veterinary microbiology Vol. 235; pp. 209 - 219
• Main Authors: Zou, Dehua, Xu, Jiaxin, Duan, Xulai, Xu, Xin, Li, Pengfei, Cheng, Lixin, Zheng, Liang, Li, Xingzhi, Zhang, Yating, Wang, Xianhe, Wu, Xuening, Shen, Yujiang, Yao, Xiangyu, Wei, Jiaqi, Yao, Lili, Li, Liyang, Song, Baifen, Ma, Jinzhu, Liu, Xinyang, Wu, Zhijun, Zhang, Hua, Cao, Hongwei
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2019; Elsevier BV
• Subjects: Accessory protein ORF3; Animals; Apoptosis; Autophagy; Cellular stress response; Chlorocebus aethiops; Confocal microscopy; Coronaviridae; Cytoplasm; Diarrhea; Endoplasmic reticulum; Endoplasmic Reticulum - pathology; Endoplasmic Reticulum - virology; Endoplasmic Reticulum Stress; Epidemics; etiological agents; Genetic Vectors; GRP78 protein; Heat-Shock Proteins - genetics; HEK293 Cells; HeLa Cells; Humans; Infectivity; ion channels; Open Reading Frames; Pathogenicity; Phagocytosis; Porcine epidemic diarrhea virus; Porcine epidemic diarrhea virus - pathogenicity; protein synthesis; Proteins; RNA viruses; Signal Transduction; Stress response; Swine; Transmissible gastroenteritis; Vero Cells; Viral Proteins - genetics; Virus Replication; Porcine epidemic diarrhea virus; Accessory protein ORF3; Autophagy; Endoplasmic reticulum stress; Apoptosis
• ISSN: 0378-1135; 1873-2542; 1873-2542
• DOI: 10.1016/j.vetmic.2019.07.005

•PEDV ORF3 is a transmembrane protein that localizes at endoplasmic reticulum to induce ER stress response.•PEDV ORF3 protein has no effect on apoptosis, but induces autophagy dependent on ER stress response.•This work provides some new findings for the biological function of the PEDV ORF3 protein. Porcine epidemic diarrhea virus (PEDV), the causative agent of PED, is an enveloped, positive-stranded RNA virus in the genus Alphacoronavirus, family Coronaviridae, order Nidovirales. PEDV non-structural accessory protein ORF3 is an ion channel related to viral infectivity and pathogenicity. Our previous study showed that PEDV ORF3 has expression characteristic of aggregation in cytoplasm, but its biological function remains elusive. Thus in this study, we initiated the construction of various vectors to express ORF3, and found ORF3 localized in the cytoplasm in the aggregation manner. Subsequently, confocal microscopy analysis showed that the aggregated ORF3 localized in endoplasmic reticulum (ER) to trigger ER stress response via up-regulation of GRP78 protein expression and activation of PERK-eIF2α signaling pathway. In addition, our results showed that PEDV ORF3 could induce the autophagy through inducing conversion of LC3-I to LC3-II, but couldn’t influence the apoptosis. In contrast, conversion of LC3-I/LC3-II could be significantly inhibited by 4-PBA, an ER stress inhibitor, indicating that ORF3-induced autophagy is dependent on ER stress response. This work not only provides some new findings for the biological function of the PEDV ORF3 protein, but also help us for the further understanding the molecular interaction between PEDV ORF3 protein and cells.