E3 ubiquitin ligase DTX2 reinforces innate antiviral immune responses by modulating K63-linked ubiquitination of TBK1
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PROVIDER: PRJNA1205741 | ENA |
REPOSITORIES: ENA
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Project description:TBK1 plays a pivotal role in innate antiviral immunity, serving as a critical mediator downstream of various pattern recognition receptors (PRRs). TBK1 activity is tightly regulated by post-translational modifications (PTMs) including ubiquitination to maintain innate immune homeostasis. Here, we identify the Deltex E3 ubiquitin ligase 2 (DTX2) as a positive regulator of innate antiviral signaling in response to RNA viruses. We find that DTX2 overexpression enhances antiviral signaling, whereas loss of DTX2 evidently reduces antiviral responses. Mechanistically, we demonstrated that DTX2 directly interacts with TBK1 and promotes TBK1 K63-linked polyubiquitination to regulate antiviral signaling. Collectively, our study reveals that DTX2 plays a novel positive regulatory role in antiviral signaling by modulating the K63-linked ubiquitination of TBK1 to maintain the balance of innate antiviral immune responses.
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Project description:The selenium-containing enzyme GPX4 moonlights as a central regulator of ferroptosis, an iron-dependent, nonapoptotic form of regulated cell death caused by lipid peroxidation. Yet, little is known about the mechanisms underlying the regulation of its post-transcriptional modifications. Here, we identify the tripartite motif-containing protein TRIM26 as an E3 ubiquitin ligase of GPX4. TRIM26 directly interacts with GPX4 through its Ring domain and catalyzes the ubiquitination of GPX4 at K107 and K117, which promotes the switch in polyubiquitination of GPX4 from K48 to K63, thus enhancing GPX4 protein stability. Moreover, PLK1-mediated S127 phosphorylation of TRIM26 enhances the interaction between TRIM26 and GPX4. Inhibition of TRIM26 phosphorylation causes a reduction in GPX4 K63-linked polyubiquitination and diminishes GPX4 protein levels in tumor cells. Further investigation revealed that TRIM26 is overexpressed in glioma cells. TRIM26 silencing dramatically impedes ferroptosis resistance and tumorigenesis in glioma in vivo and in vitro. Clinically, TRIM26 expression shows a direct correlation with GPX4 and PLK1 levels in glioma samples and is associated with poor outcome in patients with glioma. Collectively, these findings define the role of GPX4 K63-linked polyubiquitination in ferroptosis and suggest a potential strategy for glioma treatment.
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Project description:Excessive generation and accumulation of highly reactive oxidizing molecules causes oxidative stress and oxidative damage to cellular components. Accumulating evidence indicates that autophagy diminishes oxidative damage in cells and maintains redox homeostasis by degrading and recycling intracellular damaged components. However, the molecular mechanisms underlying the activation of oxidative stress-mediated autophagic response remain elusive. Here we show that ubiquitin E3 ligase TNF receptor-associated factor 6 (TRAF6) and the deubiquitinase A20 coordinate to regulate ATG9A ubiquitination and autophagy activation in cells responding to oxidative stress. The reactive oxygen species (ROS)-dependent TRAF6-mediated non-proteolytic, K48/63-linked ubiquitination of ATG9A enhances its association with Beclin 1 and the assembly of class III phosphatidylinositol-3-kinase (PI3KC3/VPS34) UVRAG complex, thereby stimulating autophagy. Notably, depletion of ATG9A or expression of the ATG9A ubiquitination mutants markedly decreases ROS-induced VPS34 activation and autophagy. We further find that lipopolysaccharide (LPS)-induced ROS production also stimulates TRAF6-mediated ATG9A ubiquitination and enhances the assembly of the UVRAG-containing VPS34 complex in an ATG9A-dependent manner. Ablation of ATG9A causes aberrant TLR4 endosomal trafficking and decreased phosphorylation of IRF-3 in LPS-stimulated macrophages. Our findings provide important insight into how K48/K63-linked ubiquitination of ATG9A contributes to the regulation of oxidative stress-induced autophagy.
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Project description:TANK-binding kinase 1 (TBK1) is essential for interferon beta (IFN-?) production and innate antiviral immunity. However, other, additional functions of TBK1 have remained elusive. Here, we showed that TBK1 is an E3 ubiquitin ligase that undergoes self-ubiquitylation in vitro in the presence of the E2 enzyme UbcH5c. Further evidence showed that TBK1 could also be self-ubiquitylated in vivo Importantly, multiple picornavirus VP3 proteins were degraded by TBK1 through its kinase and E3 ubiquitin ligase activity. Mechanistically, TBK1 phosphorylated multiple picornavirus VP3 proteins at serine residues and ubiquitinated them via K63-linked ubiquitination at lysine residues. In addition, the C426 and C605 residues of TBK1 were not essential for TBK1 innate immunity activity; however, these residues were required for degradation of multiple picornavirus VP3 proteins and for its E3 ubiquitin ligase activity. Hence, our findings identified a novel role of TBK1 in regulating the virus life cycle and provided new insights into the molecular mechanisms of TBK1-mediated antiviral response.IMPORTANCE TBK1 is an important adaptor protein required for innate immune response to viruses, but its other functions were unknown. In this study, we found that TBK1 is an E3 ubiquitin ligase that undergoes self-ubiquitylation in vitro in the presence of the E2 enzyme UbcH5c. In addition, multiple picornavirus VP3 proteins were degraded by TBK1 through its kinase and E3 ubiquitin ligase activity. Our report provides evidence that TBK1 plays a role in viral protein degradation.
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