Herpesviruses are ubiquitous in humans and they have been implicated in diverse malignancies. Human Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus are associated with tumors of lymphoid, epithelial, and endothelial origin in immuno-compromised patients. The oral cavity is a crucial compartment for gamma herpesvirus infection, particularly important for viral replication, transmission and pathogenesis. Employing human oral keratinocytes and lymphatic endothelial cells, we will delineate multiple viral immune evasion mechanisms enabled by regulated protein deamidation, the simplest post-translational modification of proteins. Host innate immunity is the first line of defense and herpesviruses have evolved an array of mechanisms to evade innate immune responses. Studying human KSHV and murine ?HV68, we have uncovered a novel immune evasion mechanism enabled by a family of viral pseudoenzymes and a cellular metabolic glutamine amidotransferase. The viral pseudoenzymes interact with the cellular glutamine amidotransferase and alter its activity to deamidate both cellular and viral proteins, potently evading the interferon induction at multiple steps. Our published and unpublished findings collectively support the conclusion that deamidation is a key mechanism regulating innate immune responses and herpesviruses exploit this mechanism to benefit their infection. In this study, we will investigate how protein deamidation regulates a cytosolic receptor in sensing viral RNA (Aim 1) and the activity of a viral protein in antagonizing interferon induction (Aim 2). Furthermore, we will define the molecular action by which KSHV and ?HV68 deploy vGAT proteins to regulate PFAS in selectively deamidating cellular and viral proteins to evade innate immune detection (Aim 3). Collectively, this study will elucidate a novel mechanism whereby protein deamidation regulates multiple steps of interferon induction, a key innate immune signaling cascade. Our work will establish more general regulatory roles of protein deamidation in fundamental biological processes, such as immune responses. Findings gleaned from this study will advance our understanding in host immune recognition and interferon induction, and potentially guide our future efforts in vaccine design and antiviral therapeutics to treat malignancies associated with human KSHV and EBV.

Public Health Relevance

We have discovered a new function of the metabolic glutamine amidotransferase in regulating innate immune signaling via deamidation. Thus, this study will focus on elucidating the molecular targets and regulation conveyed by viral pseudo-enzymes and cellular metabolic enzymes in innate immune signaling. Findings from this study will advance our understanding in immune signaling and viral infection, concerning the novel roles of protein deamidation in signal transduction.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
2R01DE021445-06A1
Application #
9381580
Study Section
Virology - B Study Section (VIRB)
Program Officer
Chander, Preethi
Project Start
2011-09-02
Project End
2018-06-30
Budget Start
2017-07-01
Budget End
2018-06-30
Support Year
6
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of Southern California
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
072933393
City
Los Angeles
State
CA
Country
United States
Zip Code
90033
Zhang, Junjie; Zhao, Jun; Xu, Simin et al. (2018) Species-Specific Deamidation of cGAS by Herpes Simplex Virus UL37 Protein Facilitates Viral Replication. Cell Host Microbe 24:234-248.e5
Feldman, Emily R; Kara, Mehmet; Oko, Lauren M et al. (2016) A Gammaherpesvirus Noncoding RNA Is Essential for Hematogenous Dissemination and Establishment of Peripheral Latency. mSphere 1:
Zhang, Junjie; Feng, Hao; Xu, Simin et al. (2016) Hijacking GPCRs by viral pathogens and tumor. Biochem Pharmacol 114:69-81
Zhao, Jun; Zeng, Yi; Xu, Simin et al. (2016) A Viral Deamidase Targets the Helicase Domain of RIG-I to Block RNA-Induced Activation. Cell Host Microbe 20:770-784
Zhao, Jun; Li, Junhua; Xu, Simin et al. (2016) Emerging Roles of Protein Deamidation in Innate Immune Signaling. J Virol 90:4262-4268
Zhang, Junjie; Feng, Hao; Zhao, Jun et al. (2016) I?B Kinase ? Is an NFATc1 Kinase that Inhibits T Cell Immune Response. Cell Rep 16:405-418
Zhao, Jun; He, Shanping; Minassian, Arlet et al. (2015) Recent advances on viral manipulation of NF-?B signaling pathway. Curr Opin Virol 15:103-11
Liang, Qiming; Chang, Brian; Lee, Patrick et al. (2015) Identification of the Essential Role of Viral Bcl-2 for Kaposi's Sarcoma-Associated Herpesvirus Lytic Replication. J Virol 89:5308-17
He, Shanping; Zhao, Jun; Song, Shanshan et al. (2015) Viral pseudo-enzymes activate RIG-I via deamidation to evade cytokine production. Mol Cell 58:134-46
Minassian, Arlet; Zhang, Junjie; He, Shanping et al. (2015) An Internally Translated MAVS Variant Exposes Its Amino-terminal TRAF-Binding Motifs to Deregulate Interferon Induction. PLoS Pathog 11:e1005060

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