STING Specifies IRF3 phosphorylation by TBK1 in the Cytosolic DNA Signaling Pathway

By Yasuo Tanaka, Zhijian J. Chen. Science Signaling, 2012

1,258 citations recorded by the source corpus.

The adaptor protein STING recruits a kinase and a transcription factor to mediate responses to cytosolic DNA. Right Place and Right Context As part of the innate immune response, various pattern recognition receptors, such as Toll-like receptor 3 (TLR3) and TLR4, activate the kinase TBK1, which phosphorylates the transcription factor IRF3, leading to the production of type I interferons (IFNs). Tanaka and Chen used an in vitro reconstitution system to investigate the mechanism by which TBK1-mediated IRF3 activation occurs in response to the presence of cytosolic DNA from viruses or bacteria, a response that depends on the adaptor protein STING (see the Perspective by Bowie). Cytosolic DNA triggered the sequential recruitment of TBK1 and IRF3 to STING, which acted as a scaffold upon which TBK1 phosphorylated both STING and IRF3. Given that not all pattern recognition receptors that stimulate TBK1 lead to IRF3 activation, the authors suggest that STING specifies the activation of IRF3 by a subset of receptors that activate both TBK1 and STING—and that other adaptor proteins may fulfill similar roles in other innate immune pathways. Cytosolic double-stranded DNA (dsDNA) stimulates the production of type I interferon (IFN) through the endoplasmic reticulum (ER)–resident adaptor protein STING (stimulator of IFN genes), which activates the transcription factor interferon regulatory factor 3 (IRF3); however, how STING activates IRF3 is unclear. Here, we showed that STING stimulates phosphorylation of IRF3 by the kinase TBK1 (TANK-binding kinase 1) in an in vitro reconstitution system. With this system, we identified a carboxyl-terminal region of STING that was both necessary and sufficient to activate TBK1 and stimulate the phosphorylation of IRF3. We also found that STING interacted with both TBK1 and IRF3 and that mutations in STING that selectively disrupted its binding to IRF3 abrogated phosphorylation of IRF3 without impairing the activation of TBK1. These results suggest that STING functions as a scaffold protein to specify and promote the phosphorylation of IRF3 by TBK1. This scaffolding function of STING (and possibly of other adaptor proteins) may explain why IRF3 is activated in only a subset of signaling pathways that activate TBK1.

Subfields: Immunology, Infectious Diseases

View Paper: https://www.semanticscholar.org/paper/ec9c98976d5d829c59005c78bba77bdacb92f9ef

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In Immunology

1. Zhijian J. Chen
2. G. Barber
3. Tuo Li
4. Jiaxi Wu
5. Lijun Sun
6. Y. Chiu
7. Xiang Chen
8. T. Abe

In Infectious Diseases

1. Zhijian J. Chen
2. Tuo Li
3. Jiaxi Wu
4. G. Barber
5. Xiang Chen
6. Lijun Sun
7. Fenghe Du
8. Xin Cai

Citations in the corpus

• Phosphorylation of innate immune adaptor proteins MAVS, STING, and TRIF induces IRF3 activation (2015, methodology): “The rabbit antibodies against human MAVS and STING were generated as described before (24, 35).”
• Cytosolic-DNA-Mediated, STING-Dependent Proinflammatory Gene Induction Necessitates Canonical NF-κB Activation through TBK1 (2014, background): “Recent reports have implicated that STING may be phosphorylated by TBK1 (48), followed by degradation to avoid the sustained production of innate immune-related proinflammatory IFN mRNA”
• Cyclic GMP-AMP Synthase is Activated by Double-stranded DNA-Induced Oligomerization (2013, background): “Ligand binding by STING induces the recruitment of the protein kinase TBK1 and transcription factor IRF-3 to the signaling complex (Tanaka and Chen, 2012).”
• Immune sensing of DNA (2013, neutral): “Tanaka and Chen (2012) showed that in response to cytosolic dsDNA, the C-terminal tail (CTT) of the CTD of STING provides 872 Immunity 38, May 23, 2013 ª2013 Elsevier Inc. a scaffold to assemble IRF3 in close proximity to TBK1, leading to TBK1-dependent phosphorylation of IRF3.”
• Cyclic GMP-AMP Synthase is a Cytosolic DNA Sensor that Activates the Type-I Interferon Pathway (2012, positive): “The lentiviral shRNA vector for knocking down mouse STING and the generation of L929/shSTING stable cells were described previously(22).”
• The cGAS-cGAMP-STING pathway of cytosolic DNA sensing and signaling. (2014, background): “However, the current structural studies do not fully explain how STING is activated because the C-terminal tail (CTT), which was previously shown to be important for STING activation (Tanaka and Chen, 2012), is not visible in any of the STING crystal structures.”
• The cGAS–cGAMP–STING pathway connects DNA damage to inflammation, senescence, and cancer (2018, background): “This process is thought to liberate the STI NG carboxyl terminus to subsequently recruit and activate TANK-binding kinase 1 (TBK1) and IFN regulatory factor 3 (IRF3) via a phosphorylationdependent mechanism (Tanaka and Chen, 2012; Liu et al., 2015).”