Chicken STING Mediates Activation of the IFN Gene Independently of the RIG-I Gene

Abstract

Stimulator of IFN genes (STING) is an adaptor that functions downstream of retinoic acid–inducible gene I (RIG-I) in mammalian cells; however, RIG-I is absent in chickens. We identified chicken STING (chSTING) as a critical mediator of virus-triggered type I IFN signaling in RIG-I–null chicken cells. Overexpression of chSTING in DF-1 cells inhibited Newcastle disease virus and avian influenza virus (AIV) viral replication and activated IRF-7 and NF-κB to induce expression of type I IFNs. Knockdown of endogenous chSTING abolished virus-triggered activation of IRF-7 and IFN-β and increased viral yield. chSTING was a critical component in the virus-triggered IRF-7 activation pathway and the cellular antiviral response. chSTING predominantly localized to the outer membrane of the endoplasmic reticulum and was also found in the mitochondrial membrane. Furthermore, knockdown of chSTING blocked polyinosinic-polycytidylic acid–, poly(deoxyadenylic-deoxythymidylic) acid–, and melanoma differentiation–associated gene 5 (MDA5)-stimulated induction of IFN-β. Coimmunoprecipitation experiments indicated that chicken MDA5 could interact with chSTING, and this interaction was enhanced by ectopically expressed chicken mitochondrial antiviral-signaling protein. Together, these results indicated that chSTING is an important regulator of chicken innate immune signaling and might be involved in the MDA5 signaling pathway in chicken cells. These results help with understanding the biological role of STING in innate immunity during evolution.

Grass Carp Laboratory of Genetics and Physiology 2 Serves As a Negative Regulator in Retinoic Acid-Inducible Gene I- and Melanoma Differentiation-Associated Gene 5-Mediated Antiviral Signaling in Resting State and Early Stage of Grass Carp Reovirus Infection

“…However, in some RIG-I-null species, such as chicken and Chinese tree shrew, MITA can interact with MDA5 to mediate the corresponding signaling. Knockdown of MITA inhibits MDA5-mediated IFN-β activation (9, 19). Therefore, experimental evidence needs to be proposed to identify whether MITA is essential for MDA5 signaling pathway in RIG-I-existed species and compare the difference between RIG-I- and MDA5-mediated MITA downstream signals.…”

“…Both RIG-I and MDA5 can sense a wide variety of RNA or DNA viruses (1, 7). Upon viral recognition, RIG-I and MDA5 activate nuclear factor κB (NF-κB) and interferon regulatory factor 3 (IRF3) through the adaptor proteins IFN-β promoter stimulator 1 [(IPS-1), also known as MAVS, VISA, or Cardif] and mediator of IRF3 activation [MITA, also named as STING] (8, 9). IPS-1 is a CARD domain-containing protein that drives the expression of type I interferons (IFN-Is) and inflammatory cytokines (1).…”

To Conquer the Host, Influenza Virus Is Packing It In: Interferon-Antagonistic Strategies beyond NS1

“…Chickens lack the RIG-I gene ddx58 (41), and IFN induction is mediated by the related RNA helicase and PRR, MDA5 (36). In contrast to mammalian STING, chicken STING forms a complex with MDA5 (and the MAVS adaptor) to induce IFN at later stages of FLUAV infection (42). Moreover, chicken MDA5 was recently identified to sense short dsRNAs, just like mammalian RIG-I (but unlike mammalian MDA5) does (43).…”

Molecular characterization, expression, and functional analysis of chicken TRAF6

“…Previous studies suggested that TRAF6 is a crucial cytoplasmic adaptor molecule responsible for the pathogen-recognition receptors (PRR)-mediated innate immune response (Bradley and Pober, 2001). The tissue distribution of TRAF6 is an important determinant of its function, and can influence the capacity of cells to detect different microorganisms during different periods in different tissues (Cheng et al, 2015). The tissue distribution of TRAF6 has been previously examined in humans (Starczynowski et al, 2011), mice (Mason et al, 2004), and ducks (Zhai et al, 2015).…”