Venezuelan Equine Encephalitis Virus Induces Apoptosis through the Unfolded Protein Response Activation of EGR1

Alan Baer; Lindsay Lundberg; Danielle Swales; Nicole Waybright; Chelsea Pinkham; Jonathan D Dinman; Jonathan L Jacobs; Kylene Kehn-Hall

doi:10.1128/JVI.02827-15

Venezuelan Equine Encephalitis Virus Induces Apoptosis through the Unfolded Protein Response Activation of EGR1

J Virol. 2016 Jan 20;90(7):3558-72. doi: 10.1128/JVI.02827-15.

Authors

Alan Baer¹, Lindsay Lundberg¹, Danielle Swales², Nicole Waybright², Chelsea Pinkham¹, Jonathan D Dinman³, Jonathan L Jacobs⁴, Kylene Kehn-Hall⁵

Affiliations

¹ National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, Virginia, USA.
² MRIGlobal, Global Health Security, Rockville, Maryland, USA.
³ University of Maryland, Department of Cell Biology and Molecular Genetics, College Park, Maryland, USA.
⁴ MRIGlobal, Global Health Security, Rockville, Maryland, USA jjacobs@mriglobal.org kkehnhal@gmu.edu.
⁵ National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, Virginia, USA jjacobs@mriglobal.org kkehnhal@gmu.edu.

Abstract

Venezuelan equine encephalitis virus (VEEV) is a previously weaponized arthropod-borne virus responsible for causing acute and fatal encephalitis in animal and human hosts. The increased circulation and spread in the Americas of VEEV and other encephalitic arboviruses, such as eastern equine encephalitis virus and West Nile virus, underscore the need for research aimed at characterizing the pathogenesis of viral encephalomyelitis for the development of novel medical countermeasures. The host-pathogen dynamics of VEEV Trinidad donkey-infected human astrocytoma U87MG cells were determined by carrying out RNA sequencing (RNA-Seq) of poly(A) and mRNAs. To identify the critical alterations that take place in the host transcriptome following VEEV infection, samples were collected at 4, 8, and 16 h postinfection and RNA-Seq data were acquired using an Ion Torrent PGM platform. Differential expression of interferon response, stress response factors, and components of the unfolded protein response (UPR) was observed. The protein kinase RNA-like endoplasmic reticulum kinase (PERK) arm of the UPR was activated, as the expression of both activating transcription factor 4 (ATF4) and CHOP (DDIT3), critical regulators of the pathway, was altered after infection. Expression of the transcription factor early growth response 1 (EGR1) was induced in a PERK-dependent manner. EGR1(-/-) mouse embryonic fibroblasts (MEFs) demonstrated lower susceptibility to VEEV-induced cell death than isogenic wild-type MEFs, indicating that EGR1 modulates proapoptotic pathways following VEEV infection. The influence of EGR1 is of great importance, as neuronal damage can lead to long-term sequelae in individuals who have survived VEEV infection.

Importance: Alphaviruses represent a group of clinically relevant viruses transmitted by mosquitoes to humans. In severe cases, viral spread targets neuronal tissue, resulting in significant and life-threatening inflammation dependent on a combination of virus-host interactions. Currently there are no therapeutics for infections cause by encephalitic alphaviruses due to an incomplete understanding of their molecular pathogenesis. Venezuelan equine encephalitis virus (VEEV) is an alphavirus that is prevalent in the Americas and that is capable of infecting horses and humans. Here we utilized next-generation RNA sequencing to identify differential alterations in VEEV-infected astrocytes. Our results indicated that the abundance of transcripts associated with the interferon and the unfolded protein response pathways was altered following infection and demonstrated that early growth response 1 (EGR1) contributed to VEEV-induced cell death.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Animals
Apoptosis*
Cell Line
Early Growth Response Protein 1 / genetics
Early Growth Response Protein 1 / metabolism*
Encephalitis Virus, Venezuelan Equine / physiology*
Gene Expression Profiling
Host-Pathogen Interactions*
Humans
Mice
Mice, Knockout
Unfolded Protein Response*

Substances

Early Growth Response Protein 1
Egr1 protein, mouse

Grants and funding

This work was funded through a Defense Threat Reduction Agency grant, HDTRA1-13-1-0005, to K.K.-H. and J.L.J. The content of this article does not necessarily reflect the position or the policy of the federal government, and no official endorsement should be inferred.