E3 Ubiquitin Ligase Nedd4 Promotes Japanese Encephalitis Virus Replication by Suppressing Autophagy in Human Neuroblastoma Cells

Qingqiang Xu,Shenglin Chen,Naiwei Zhu,Shiying Zhu,Zhongtian Qi,Hailin Tang,Hao Ren,Ping Zhao,Yongzhe Zhu

doi:10.1038/srep45375

Abstract

Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that causes the most prevalent viral encephalitis in Asia. Since JEV is a neurotropic virus, it is important to identify key molecules that mediate JEV infection in neuronal cells and to investigate their underlying mechanisms. In this study, the critical role of Nedd4, an E3 ubiquitin ligase that is highly expressed in the central nervous system, was examined in JEV propagation. In SK-N-SH neuroblastoma cells, Nedd4 was up-regulated in response to JEV infection. Moreover, down-regulation of Nedd4 resulted in a significant decrease in JEV replication without alterations in virus attachment and internalization or in JEV pseudotyped virus infection, suggesting that Nedd4 participates in the replication but not in the entry stage of JEV infection. Further functional analysis showed that Nedd4 attenuated JEV-induced autophagy, which negatively regulates virus replication during infection. These results suggest that Nedd4 facilitates the replication of JEV by suppressing virus-induced autophagy. Taken together, our results indicate that Nedd4 plays a crucial role in JEV infection of neuronal cells, which provides a potential target for the development of novel treatment to combat JEV infection.

Highlights

IntroductionNedd[4] (neuronal precursor cell-expressed, developmentally downregulated 4) is an E3 ubiquitin ligase with a catalytic domain of the HECT class
Our results indicate the crucial role of Nedd[4] in Japanese encephalitis virus (JEV) infection of neuronal cells, and provide a potential target for developing novel antiviral strategies to combat JEV
To determine whether JEV infection alters Nedd[4] expression, SK-N-SH cells were infected with JEV at a multiplicity of infection (MOI) of 1.0, and Nedd[4] mRNA levels were determined by quantitative real time PCR (RT-qPCR) at different time points post infection (p.i.)

Summary

Introduction

Nedd[4] (neuronal precursor cell-expressed, developmentally downregulated 4) is an E3 ubiquitin ligase with a catalytic domain of the HECT class. Nedd[4] has been shown to play important physiological roles in regulating almost every facet of neuronal function, from development to neurotransmission and synaptic plasticity[13]. It has been identified as an important regulator of dendrite formation and arborization in both hippocampal and cortical neurons[14,15]. Our results indicate the crucial role of Nedd[4] in JEV infection of neuronal cells, and provide a potential target for developing novel antiviral strategies to combat JEV

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Results

Conclusion