Format

Send to

Choose Destination
Front Microbiol. 2017 Feb 20;8:240. doi: 10.3389/fmicb.2017.00240. eCollection 2017.

HELZ2 Is an IFN Effector Mediating Suppression of Dengue Virus.

Author information

1
Gastrointestinal Division, Department of Medicine, Massachusetts General HospitalBoston, MA, USA; Division of Infectious Diseases, Vaccine and Immunotherapy Center, Department of Medicine, Massachusetts General HospitalBoston, MA, USA; Laboratory for Systems Pharmacology, Harvard Medical SchoolBoston, MA, USA.
2
Gastrointestinal Division, Department of Medicine, Massachusetts General Hospital Boston, MA, USA.
3
Division of Infectious Diseases, Vaccine and Immunotherapy Center, Department of Medicine, Massachusetts General HospitalBoston, MA, USA; Department of Medicine, Athens University Medical SchoolAthens, Greece.
4
Department of Biology, Wellesley College Wellesley, MA, USA.
5
Department of Molecular Biology, Massachusetts General Hospital Boston, MA, USA.
6
Laboratory for Systems Pharmacology, Harvard Medical School Boston, MA, USA.
7
Division of Cardiology, Department of Medicine, Beth Israel Deaconess Medical Center Boston, MA, USA.
8
Division of Cardiology, Department of Medicine, Massachusetts General Hospital Boston, MA, USA.
9
Division of Cardiology, Department of Medicine, Beth Israel Deaconess Medical CenterBoston, MA, USA; Division of Cardiology, Department of Medicine, Massachusetts General HospitalBoston, MA, USA.
10
Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine Maebashi, Japan.

Abstract

Flaviviral infections including dengue virus are an increasing clinical problem worldwide. Dengue infection triggers host production of the type 1 IFN, IFN alpha, one of the strongest and broadest acting antivirals known. However, dengue virus subverts host IFN signaling at early steps of IFN signal transduction. This subversion allows unbridled viral replication which subsequently triggers ongoing production of IFN which, again, is subverted. Identification of downstream IFN antiviral effectors will provide targets which could be activated to restore broad acting antiviral activity, stopping the signal to produce endogenous IFN at toxic levels. To this end, we performed a targeted functional genomic screen for IFN antiviral effector genes (IEGs), identifying 56 IEGs required for antiviral effects of IFN against fully infectious dengue virus. Dengue IEGs were enriched for genes encoding nuclear receptor interacting proteins, including HELZ2, MAP2K4, SLC27A2, HSP90AA1, and HSP90AB1. We focused on HELZ2 (Helicase With Zinc Finger 2), an IFN stimulated gene and IEG which encodes a promiscuous nuclear factor coactivator that exists in two isoforms. The two unique HELZ2 isoforms are both IFN responsive, contain ISRE elements, and gene products increase in the nucleus upon IFN stimulation. Chromatin immunoprecipitation-sequencing revealed that the HELZ2 complex interacts with triglyceride-regulator LMF1. Mass spectrometry revealed that HELZ2 knockdown cells are depleted of triglyceride subsets. We thus sought to determine whether HELZ2 interacts with a nuclear receptor known to regulate immune response and lipid metabolism, AHR, and identified HELZ2:AHR interactions via co-immunoprecipitation, found that AHR is a dengue IEG, and that an AHR ligand, FICZ, exhibits anti-dengue activity. Primary bone marrow derived macrophages from HELZ2 knockout mice, compared to wild type controls, exhibit enhanced dengue infectivity. Overall, these findings reveal that IFN antiviral response is mediated by HELZ2 transcriptional upregulation, enrichment of HELZ2 protein levels in the nucleus, and activation of a transcriptional program that appears to modulate intracellular lipid state. IEGs identified in this study may serve as both (1) potential targets for host directed antiviral design, downstream of the common flaviviral subversion point, as well as (2) possible biomarkers, whose variation, natural, or iatrogenic, could affect host response to viral infections.

KEYWORDS:

genes that are required for IFN-mediated suppression of virus; interferon; interferon effector gene (IEG)

Supplemental Content

Full text links

Icon for Frontiers Media SA Icon for PubMed Central
Loading ...
Support Center