An Alternative STAT Signaling Pathway Acts in Viral Immunity in Caenorhabditis elegans

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Title: An Alternative STAT Signaling Pathway Acts in Viral Immunity in Caenorhabditis elegans
Authors: Sarkies, P
Tanguy, M
Veron, L
Stempor, P
Ahringer, J
Miska, E
Item Type: Journal Article
Abstract: Across metazoans, innate immunity is vital in defending organisms against viral infection. In mammals, antiviral innate immunity is orchestrated by interferon signaling, activating the STAT transcription factors downstream of the JAK kinases to induce expression of antiviral effector genes. In the nematode Caenorhabditis elegans, which lacks the interferon system, the major antiviral response so far described is RNA interference (RNAi), but whether additional gene expression responses are employed is not known. Here we show that, despite the absence of both interferon and JAK, the C. elegans STAT homolog STA-1 orchestrates antiviral immunity. Intriguingly, mutants lacking STA-1 are less permissive to antiviral infection. Using gene expression analysis and chromatin immunoprecipitation, we show that, in contrast to the mammalian pathway, STA-1 acts mostly as a transcriptional repressor. Thus, STA-1 might act to suppress a constitutive antiviral response in the absence of infection. Additionally, using a reverse genetic screen, we identify the kinase SID-3 as a new component of the response to infection, which, along with STA-1, participates in the transcriptional regulatory network of the immune response. Our work uncovers novel physiological roles for two factors in viral infection: a SID protein acting independently of RNAi and a STAT protein acting in C. elegans antiviral immunity. Together, these results illustrate the complex evolutionary trajectory displayed by innate immune signaling pathways across metazoan organisms. IMPORTANCE Since innate immunity was discovered, a diversity of pathways has arisen as powerful first-line defense mechanisms to fight viral infection. RNA interference, reported mostly in invertebrates and plants, as well as the mammalian interferon response and JAK/STAT pathway are key in RNA virus innate immunity. We studied infection by the Orsay virus in Caenorhabditis elegans, where RNAi is known to be a potent antiviral defense. We show that, in addition to its RNAi pathway, C. elegans utilizes an alternative STAT pathway to control the levels of viral infection. We identify the transcription factor STA-1 and the kinase SID-3 as two components of this response. Our study defines C. elegans as a new example of the diversity of antiviral strategies.
Issue Date: 5-Sep-2017
Date of Acceptance: 22-Aug-2017
ISSN: 2150-7511
Publisher: American Society for Microbiology
Journal / Book Title: mBio
Volume: 8
Issue: 5
Copyright Statement: Copyright © 2017 Tanguy et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.
Sponsor/Funder: Medical Research Council
Funder's Grant Number: MC-A652-5PZ80-3203-0000-0000
Keywords: 0605 Microbiology
Publication Status: Published
Open Access location:
Article Number: e00924-17
Appears in Collections:Clinical Sciences
Molecular Sciences
Faculty of Medicine

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