Japanese encephalitis virus induces human neural stem/progenitor cell death by elevating GRP78, PHB and hnRNPC through ER stress

Sriparna Mukherjee,Noopur Singh,Mahar Fatima,Nabonita Sengupta,Anita Mahadevan,Pankaj Seth,Susarla Krishna Shankar,Anirban Basu,Arindam Bhattacharyya

doi:10.1038/cddis.2016.394

Abstract

Japanese encephalitis virus (JEV), which is a causative agent of sporadic encephalitis, harbours itself inside the neural stem/progenitor cells. It is a well-known fact that JEV infects neural stem/progenitor cells and decreases their proliferation capacity. With mass spectrometry-based quantitative proteomic study, it is possible to reveal the impact of virus on the stem cells at protein level. Our aim was to perceive the stem cell proteomic response upon viral challenge. We performed a two-dimensional gel electrophoresis-based proteomic study of the human neural stem cells (hNS1 cell line) post JEV infection and found that 13 proteins were differentially expressed. The altered proteome profile of hNS1 cell line revealed sustained endoplasmic reticulum stress, which deteriorated normal cellular activities leading to cell apoptosis. The proteomic changes found in hNS1 cell line were validated in vivo in the subventricular zone of JE infected BALB/c mice. Congruent alterations were also witnessed in multipotent neural precursor cells isolated from human foetus and in autopsy samples of human brain clinically diagnosed as cases of JE patients. Endoplasmic reticulum resident chaperone GRP78, mitochondrial protein Prohibitin and heterogeneous nuclear ribonucleoprotein hnRNPC (C1/C2) have been shown to interact with viral RNA. Hence it is proposed that these are the principle candidates governing endoplasmic reticulum stress-induced apoptosis in JEV infection.

Highlights

Japanese encephalitis virus (JEV), a deadly neurotropic pathogen with single stranded RNA, causes endemic encephalitis in the tropical countries of South-East Asia
JEV has been shown to enter the neural stem progenitor cells (NSPCs) via lipid raft dependent endocytosis[2] and promote immunological damage in the NSPCs and diminish their proliferation, which accomplish for the neurobehavioural outcome in the survivors.[3,4]
We found the significant increase of caspases along with cytochrome C release (Figure 6b), which reaffirmed about elicitation of similar host response of NSPCs post JEV infection

Summary

Introduction

Japanese encephalitis virus (JEV), a deadly neurotropic pathogen with single stranded RNA, causes endemic encephalitis in the tropical countries of South-East Asia. Promoting apoptosis in NSPCs following ER stress.[14] Zika virus is reported to infect neural progenitors resulting in microcephaly.[15] clear understandings of death mediators that are governed by ER stress in JEV infection have not yet been established. Our investigations uncovered three viral RNA interacting proteins GRP78, Prohibitin (PHB) and hnRNPC, whose suppression reduced viral infection, and minimized stress response and resultant apoptosis. We propose these proteins as cardinal modulators of ER stress progressing to apoptosis in human neural stem cells, post JEV infection

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