The ORF3 Protein of Genotype 1 Hepatitis E Virus Suppresses TLR3-induced NF-κB Signaling via TRADD and RIP1.
Hepatitis E virus (HEV) genotype 1 infection is common and can emerge as outbreaks in developing areas, thus posing a threat to public health. However, due to the absence of feasible animal models, the mechanism of HE pathogenesis remains obscure. The HEV pathogenic mechanism has been suggested to be mediated by the immune system and not by direct viral duplication. We firstly discovered that the open reading frame 3 (ORF3) protein of genotype 1 HEV downregulates TLR3-mediated NF-κB signaling in Human A549 Lung Epithelial Cells (A549 cells) which were exposed to different TLR agonists associated with viral nucleic acids. Additionally, we identified the P2 domain of ORF3 as being responsible for this inhibition. Intriguingly, tumor necrosis factor receptor 1-associated death domain protein (TRADD) expression and receptor-interacting protein kinase 1 (RIP1) K63-ubiquitination were reduced in the presence of both ORF3 and Poly(I:C). Furthermore, we found that Lys377 of RIP1 acts as the functional ubiquitination site for ORF3-associated inhibition. Overall, we found that ORF3 protein downregulates TLR3-mediated NF-κB signaling via TRADD and RIP1. Our findings provide a new perspective on the cellular response in HEV infection and expand our understanding of the molecular mechanisms of HEV pathogenesis in innate immunity.
Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
Man
M
He
Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
Min
M
Wang
Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
Ying
Y
Huang
Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
Wenju
W
Peng
National Institute of Diagnostics and Vaccine Development in Infectious Disease, School of Public Health, Xiamen University, Xiamen, 361005, China.
Zizheng
Z
Zheng
National Institute of Diagnostics and Vaccine Development in Infectious Disease, School of Public Health, Xiamen University, Xiamen, 361005, China.
Ningshao
N
Xia
Department of Infectious Disease, the Central Hospital of Fuling District, Chongqing, 404100, China.
Jian
J
Xu
Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
Deying
D
Tian
D000072283:A549 Cells; D005786:Gene Expression Regulation / Q000235:genetics; D005838:Genotype; D016751:Hepatitis E / Q000235:genetics* / Q000821:virology; D016752:Hepatitis E virus / Q000235:genetics* / Q000472:pathogenicity; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics; D016328:NF-kappa B / Q000235:genetics; D028861:Nuclear Pore Complex Proteins / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics*; D053199:TNF Receptor-Associated Death Domain Protein / Q000235:genetics*; D051196:Toll-Like Receptor 3 / Q000235:genetics; D054875:Ubiquitination / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics*
C119724:AGFG1 protein, human; D016328:NF-kappa B; D028861:Nuclear Pore Complex Proteins; C400973:ORF3 protein, Hepatitis E virus; D016601:RNA-Binding Proteins; C495344:TLR3 protein, human; D053199:TNF Receptor-Associated Death Domain Protein; D051196:Toll-Like Receptor 3; D014764:Viral Proteins