Phosphorylation of aryl hydrocarbon receptor interacting protein by TBK1 negatively regulates IRF7 and the type I interferon response.

The innate antiviral response to RNA viruses is initiated by sensing of viral RNAs by RIG-I-like receptors and elicits type I interferon (IFN) production, which stimulates the expression of IFN-stimulated genes that orchestrate the antiviral response to prevent systemic infection. Negative regulation of type I IFN and its master regulator, transcription factor IRF7, is essential to maintain immune homeostasis. We previously demonstrated that AIP (aryl hydrocarbon receptor interacting protein) functions as a negative regulator of the innate antiviral immune response by binding to and sequestering IRF7 in the cytoplasm, thereby preventing IRF7 transcriptional activation and type I IFN production. However, it remains unknown how AIP inhibition of IRF7 is regulated. We show here that the kinase TBK1 phosphorylates AIP and Thr40 serves as the primary target for TBK1 phosphorylation. AIP Thr40 plays critical roles in regulating AIP stability and mediating its interaction with IRF7. The AIP phosphomimetic T40E exhibited increased proteasomal degradation and enhanced interaction with IRF7 compared with wildtype AIP. AIP T40E also blocked IRF7 nuclear translocation, which resulted in reduced type I IFN production and increased viral replication. In sharp contrast, AIP phosphonull mutant T40A had impaired IRF7 binding, and stable expression of AIP T40A in AIP-deficient mouse embryonic fibroblasts elicited a heightened type I IFN response and diminished RNA virus replication. Taken together, these results demonstrate that TBK1-mediated phosphorylation of AIP at Thr40 functions as a molecular switch that enables AIP to interact with and inhibit IRF7, thus preventing overactivation of type I IFN genes by IRF7.

CDK12 loss inhibits cell proliferation by regulating TBK1 in non-small cell lung cancer cells.

Lung cancer is one of the most common malignant tumors and has a poor prognosis and a low survival rate. Traditional treatments, such as radiotherapy and chemotherapy, still face some challenges because of high drug resistance and toxicity. Therefore, it is necessary to discover a new kind of targeted drug with low toxicity and high efficiency. CDK12 is a cell cycle-dependent kinase whose main function is to activate RNA polymerase II (RNAPII) and promote the transcriptional extension of RNA. However, the role and molecular mechanism of CDK12 in lung cancer are still unclear. In this study, the mutation and RNA-Seq data of CDK12 in lung adenocarcinoma and squamous cell carcinoma were downloaded from The Cancer Genome Atlas (TCGA) database and analyzed with the custom scripts. Cell proliferation was evaluated by Cell Counting Kit-8 (CCK-8) and cell colony formation assays. A subcutaneous tumor experiment in nude mice was used to examine the effects of CDK12 knockdown on the in vivo tumor growth of NSCLC cells. The cell cycle distribution and the apoptosis rate of lung cancer cells were assessed by flow cytometry. Regulation of TANK-binding kinase 1 (TBK1) by CDK12 was evaluated by quantitative PCR, immunoprecipitation and Western blot analysis. In this study we have analyzed the mutation and expression data of The Cancer Genome Atlas (TCGA) database and found that CDK12 is highly expressed in lung cancer tissues. Clinical correlation analysis showed that high expression of CDK12 in NSCLC reduces patient survival, but its high expression is only related to early tumor progression and has no significant correlation with late tumor progression and metastasis. Furthermore, we present evidence that CDK12 depletion in lung cancer cell lines not only leads to the inhibition of cell growth and induces apoptosis but also inhibits tumor growth of NSCLC cells in vivo. CDK12 positively regulates the expression of the oncogene TBK1 in lung cancer cells. These results revealed that CDK12 affects the progression of non-small cell lung cancer through positive regulation of TBK1 expression, suggesting that CDK12 might be a potential molecular target for the treatment of non-small cell lung cancer.

TBK1 interacts with tau and enhances neurodegeneration in tauopathy.

One of the defining pathological features of Alzheimer's disease (AD) is the deposition of neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau in the brain. Aberrant activation of kinases in AD has been suggested to enhance phosphorylation and toxicity of tau, making the responsible tau kinases attractive therapeutic targets. The full complement of tau-interacting kinases in AD brain and their activity in disease remains incompletely defined. Here, immunoaffinity enrichment coupled with mass spectrometry (MS) identified TANK-binding kinase 1 (TBK1) as a tau-interacting partner in human AD cortical brain tissues. We validated this interaction in human AD, familial frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) caused by mutations in MAPT (R406W & P301L) and corticobasal degeneration (CBD) postmortem brain tissues as well as human cell lines. Further, we document increased TBK1 activation in both AD and FTDP-17 and map TBK1 phosphorylation sites on tau based on in vitro kinase assays coupled to MS. Lastly, in a Drosophila tauopathy model, activating expression of a conserved TBK1 ortholog triggers tau hyperphosphorylation and enhanced neurodegeneration, whereas knockdown had the reciprocal effect, suppressing tau toxicity. Collectively, our findings suggest that increased TBK1 activation may promote tau hyperphosphorylation and neuronal loss in AD and related tauopathies.

InsP3R-SEC5 interaction on phagosomes modulates innate immunity to Candida albicans by promoting cytosolic Ca2+ elevation and TBK1 activity.

BACKGROUND: Candida albicans (C. albicans) invasion triggers antifungal innate immunity, and the elevation of cytoplasmic Ca2+ levels via the inositol 1,4,5-trisphosphate receptor (InsP3R) plays a critical role in this process. However, the molecular pathways linking the InsP3R-mediated increase in Ca2+ and immune responses remain elusive. RESULTS: In the present study, we find that during C. albicans phagocytosis in macrophages, exocyst complex component 2 (SEC5) promotes InsP3R channel activity by binding to its C-terminal α-helix (H1), increasing cytosolic Ca2+ concentrations ([Ca2+]c). Immunofluorescence reveals enriched InsP3R-SEC5 complex formation on phagosomes, while disruption of the InsP3R-SEC5 interaction by recombinant H1 peptides attenuates the InsP3R-mediated Ca2+ elevation, leading to impaired phagocytosis. Furthermore, we show that C. albicans infection promotes the recruitment of Tank-binding kinase 1 (TBK1) by the InsP3R-SEC5 interacting complex, leading to the activation of TBK1. Subsequently, activated TBK1 phosphorylates interferon regulatory factor 3 (IRF-3) and mediates type I interferon responses, suggesting that the InsP3R-SEC5 interaction may regulate antifungal innate immune responses not only by elevating cytoplasmic Ca2+ but also by activating the TBK1-IRF-3 pathway. CONCLUSIONS: Our data have revealed an important role of the InsP3R-SEC5 interaction in innate immune responses against C. albicans.

Inhibition of TBK1 reduces choroidal neovascularization in vitro and in vivo.

choroidal neovascularization (CNV), a characteristic of wet age-related macular degeneration (AMD), causes severe vision loss among elderly patients. TANK-binding kinase 1 (TBK1) is a ubiquitously expressed serine-threonine kinase and is found to induce endothelial cells proliferation, represent a novel mediator of tumor angiogenesis and exert pro-inflammatory effect. However, the role of TBK1 in choroidal neovascularization has not been investigated so far. In this study, we found that the expression of TBK1 and VEGF was up-regulated in RF/6 A cells chemical hypoxia model and laser-induced mouse CNV model. Silencing of TBK1 suppressed the proliferation and tube formation activity of RF/6 A cells. Intravitreal injection of anti-TBK1 monoclonal antibody ameliorates CNV formation. Taken together, these findings exhibit a proangiogenic role for TBK1 via upregulating the expression of VEGF, and may suggest that TBK1 inhibition offers a unique and alternative method for prevention and treatment of AMD.

Design, synthesis, and biological activity of substituted 2-amino-5-oxo-5H-chromeno[2,3-b]pyridine-3-carboxylic acid derivatives as inhibitors of the inflammatory kinases TBK1 and IKKε for the treatment of obesity.

The non-canonical IκB kinases TANK-binding kinase 1 (TBK1) and inhibitor of nuclear factor kappa-B kinase ε (IKKε) play a key role in insulin-independent pathways that promote energy storage and block adaptive energy expenditure during obesity. Utilizing docking calculations and the x-ray structure of TBK1 bound to amlexanox, an inhibitor of these kinases with modest potency, a series of analogues was synthesized to develop a structure activity relationship (SAR) around the A- and C-rings of the core scaffold. A strategy was developed wherein R7 and R8 A-ring substituents were incorporated late in the synthetic sequence by utilizing palladium-catalyzed cross-coupling reactions on appropriate bromo precursors. Analogues display IC50 values as low as 210 nM and reveal A-ring substituents that enhance selectivity toward either kinase. In cell assays, selected analogues display enhanced phosphorylation of p38 or TBK1 and elicited IL-6 secretion in 3T3-L1 adipocytes better than amlexanox. An analogue bearing a R7 cyclohexyl modification demonstrated robust IL-6 production in 3T3-L1 cells as well as a phosphorylation marker of efficacy and was tested in obese mice where it promoted serum IL-6 response, weight loss, and insulin sensitizing effects comparable to amlexanox. These studies provide impetus to expand the SAR around the amlexanox core toward uncovering analogues with development potential.

A20 regulates atherogenic interferon (IFN)-γ signaling in vascular cells by modulating basal IFNß levels.

IFNγ signaling in endothelial (EC) and smooth muscle cells (SMC) is a key culprit of pathologic vascular remodeling. The impact of NF-κB inhibitory protein A20 on IFNγ signaling in vascular cells remains unknown. In gain- and loss-of-function studies, A20 inversely regulated expression of IFNγ-induced atherogenic genes in human EC and SMC by modulating STAT1 transcription. In vivo, inadequate A20 expression in A20 heterozygote mice aggravated intimal hyperplasia following partial carotid artery ligation. This outcome uniquely associated with increased levels of Stat1 and super-induction of Ifnγ-dependent genes. Transcriptome analysis of the aortic media from A20 heterozygote versus wild-type mice revealed increased basal Ifnß signaling as the likely cause for higher Stat1 transcription. We confirmed higher basal IFNß levels in A20-silenced human SMC and showed that neutralization or knockdown of IFNß abrogates heightened STAT1 levels in these cells. Upstream of IFNß, A20-silenced EC and SMC demonstrated higher levels of phosphorylated/activated TANK-binding kinase-1 (TBK1), a regulator of IFNß transcription. This suggested that A20 knockdown increased STAT1 transcription by enhancing TBK1 activation and subsequently basal IFNß levels. Altogether, these results uncover A20 as a key physiologic regulator of atherogenic IFNγ/STAT1 signaling. This novel function of A20 added to its ability to inhibit nuclear factor-κB (NF-κB) activation solidifies its promise as an ideal therapeutic candidate for treatment and prevention of vascular diseases. In light of recently discovered A20/TNFAIP3 (TNFα-induced protein 3) single nucleotide polymorphisms that impart lower A20 expression or function, these results also qualify A20 as a reliable clinical biomarker for vascular risk assessment.

TRAF7 negatively regulates the RLR signaling pathway by facilitating the K48-linked ubiquitination of TBK1.

TANK-binding kinase 1 (TBK1) is a nodal protein involved in multiple signal transduction pathways. In RNA virus-mediated innate immunity, TBK1 is recruited to the prion-like platform formed by MAVS and subsequently activates the transcription factors IRF3/7 and NF-κB to produce type I interferon (IFN) and proinflammatory cytokines for the signaling cascade. In this study, TRAF7 was identified as a negative regulator of innate immune signaling. TRAF7 interacts with TBK1 and promotes K48-linked polyubiquitination and degradation of TBK1 through its RING domain, impairing the activation of IRF3 and the production of IFN-ß. In addition, we found that the conserved cysteine residues at position 131 of TRAF7 are necessary for its function toward TBK1. Knockout of TRAF7 could facilitate the activation of IRF3 and increase the transcript levels of downstream antiviral genes. These data suggest that TRAF7 negatively regulates innate antiviral immunity by promoting the K48-linked ubiquitination of TBK1.

MiR-217 targets TBK1 to modulate inflammatory response in grass carp following infection with Aeromonas hydrophila.

The current study demonstrated that miR-217 modulates inflammation in grass carp (Ctenopharyngodon Idella) infected with Aeromonas hydrophila. Bacterial infection in grass carp causes high levels septicemia, which arises with systemic inflammatory responses. As a result leading to the development of hyperinflammatory state which causes septic shocks and lethality. Based on the current data, TBK1 was confirmed to be the target gene of miR-217 after a successful gene expression profiling or luciferase experiment and miR-217 expression in CIK cells. Furthermore, TargetscanFish6.2 predicted TBK1 as the target gene of miR-217. Quantitative real-time PCR was performed to measure miR-217 expression levels for six immune-related genes and miR-217 regulation in grass carp after A. hydrophila infection in CIK cells. In grass carp CIK cells, the expression of TBK1 mRNA was up-regulated under poly (I: C) stimulation. The transcriptional analysis of the immune-related genes demonstrated that the expression levels of tumor necrosis factor-α (TNF-α), interferon (ifn), interleukin 6 (il-6), interleukin 8 (il-8), and interleukin 12 (il-12) were altered after a successful transfection into the CIK cells, proposing that miRNA regulates immune responses in grass carp. These results provided a theoretical basis and contribute to further studies on the pathogenesis and host defensive system during A. hydrophila infection.

Inosine: A broad-spectrum anti-inflammatory against SARS-CoV-2 infection-induced acute lung injury via suppressing TBK1 phosphorylation.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced cytokine storms constitute the primary cause of coronavirus disease 19 (COVID-19) progression, severity, criticality, and death. Glucocorticoid and anti-cytokine therapies are frequently administered to treat COVID-19, but have limited clinical efficacy in severe and critical cases. Nevertheless, the weaknesses of these treatment modalities have prompted the development of anti-inflammatory therapy against this infection. We found that the broad-spectrum anti-inflammatory agent inosine downregulated proinflammatory interleukin (IL)-6, upregulated anti-inflammatory IL-10, and ameliorated acute inflammatory lung injury caused by multiple infectious agents. Inosine significantly improved survival in mice infected with SARS-CoV-2. It indirectly impeded TANK-binding kinase 1 (TBK1) phosphorylation by binding stimulator of interferon genes (STING) and glycogen synthase kinase-3ß (GSK3ß), inhibited the activation and nuclear translocation of the downstream transcription factors interferon regulatory factor (IRF3) and nuclear factor kappa B (NF-κB), and downregulated IL-6 in the sera and lung tissues of mice infected with lipopolysaccharide (LPS), H1N1, or SARS-CoV-2. Thus, inosine administration is feasible for clinical anti-inflammatory therapy against severe and critical COVID-19. Moreover, targeting TBK1 is a promising strategy for inhibiting cytokine storms and mitigating acute inflammatory lung injury induced by SARS-CoV-2 and other infectious agents.

Ubiquitin-specific protease 24 promotes EV71 infection by restricting K63-linked polyubiquitination of TBK1.

TANK-binding kinase 1 (TBK1) is an essential protein kinase for activation of interferon regulatory factor 3 (IRF3) and induction of the type I interferons (IFN-I). Although the biochemical regulation of TBK1 activation has been studied, little is known about how enterovirus 71 (EV71) employs the deubiquitinases (DUBs) to regulate TBK1 activation for viral immune evasion. Here, we found that EV71 infection upregulated the expression of ubiquitin-specific protease 24 (USP24). Further studies revealed that USP24 physically interacted with TBK1, and can reduce K63-linked polyubiquitination of TBK1. Knockdown of USP24 upregulated TBK1 K63-linked polyubiquitination, promoted the phosphorylation and nuclear translocation of IRF3, and in turn improved IFN-I production during EV71 infection. As a consequence, USP24 knockdown dramatically inhibited EV71 infection. This study revealed USP24 as a novel regulator of TBK1 activation, which promotes the understanding of immune evasion mechanisms of EV71 and could provide a potential strategy for treatment of EV71 infection.

Zika virus non-structural protein 4B interacts with DHCR7 to facilitate viral infection.

Zika virus (ZIKV) evolves non-structural proteins to evade immune response and ensure efficient replication in the host cells. Cholesterol metabolic enzyme 7-dehydrocholesterol reductase (DHCR7) was recently reported to impact innate immune responses in ZIKV infection. However, the vital non-structural protein and mechanisms involved in DHCR7-mediated viral evasion are not well elucidated. In this study, we demonstrated that ZIKV infection facilitated DHCR7 expression. Notably, the upregulated DHCR7 in turn facilitated ZIKV infection and blocking DHCR7 suppressed ZIKV infection. Mechanically, ZIKV non-structural protein 4B (NS4B) interacted with DHCR7 to induce DHCR7 expression. Moreover, DHCR7 inhibited TANK-binding kinase 1 (TBK1) and interferon regulatory factor 3 (IRF3) phosphorylation, which resulted in the reduction of interferon-beta (IFN-ß) and interferon-stimulated genes (ISGs) productions. Therefore, we propose that ZIKV NS4B binds to DHCR7 to repress TBK1 and IRF3 activation, which in turn inhibits IFN-ß and ISGs, and thereby facilitating ZIKV evasion. This study broadens the insights on how viral non-structural proteins antagonize innate immunity to facilitate viral infection via cholesterol metabolic enzymes and intermediates.

Novel Intronic Mutations of TBK1 Promote Aberrant Splicing Modes in Amyotrophic Lateral Sclerosis.

TANK-binding kinase 1 (TBK1) has been identified as a causative gene of amyotrophic lateral sclerosis (ALS) in the Caucasian population in 2015. Here, we sequenced for TBK1 variants in a cohort of 15 familial ALS (fALS) and 275 sporadic ALS (sALS) of Chinese origin by targeted next-generation sequencing. We identified one likely benign missense variant (p. Ser398Pro), two missense variants of uncertain significance (p. Ile37Leu and p. Tyr677Asn), and two novel heterozygous variants in introns of TBK1, c.1522-3T > G and c.2066 + 4A > G. We performed splicing assays through minigene plasmids and RNA pull-down assay to determine that the two substitutions of nucleotides disrupted the binding of the important splicing regulator hnRNPA1 and promoted aberrant pre-mRNA splicing modes. The c.1522-3T > G variant promoted nearly 50.0% of abnormal transcripts (3 different types of insertions and deletions (indels) in junction of intron 13-exon 14) and the c.2066 + 4A > G variant inhibited about 75.0% inclusion of exon 19, both causing premature stop codon and producing TBK1 protein without CCD2. Immunofluorescence analysis showed that the expression of TBK1 with intronic variants was lower since less TBK1 distribution was observed in HEK293T cells. Both patients carrying TBK1 c.1522-3T > G and c.2066 + 4A > G variants developed a rapidly progressive ALS, with a survival of 31 and 10 months, respectively. The frequency of loss of function (LoF) variants in TBK1 was 0.73% in sALS in our cohort. We emphasize that intronic sequencing and pre-mRNA splicing analysis cannot be ignored to demonstrate the complex mutational spectrum and pathogenesis of ALS.

LINC00483 promotes proliferation and metastasis through the miR-19a-3p/TBK1/MAPK axis in pancreatic ductal adenocarcinoma (PDAC).

Background: Long noncoding RNAs (lncRNAs) have been found to promote tumor progression. However, the role of lncRNAs in pancreatic ductal adenocarcinoma (PDAC) requires more investigation. Methods: In this study, microarray was used to measure lncRNA levels in 3 pairs of PDAC tissues. As the highest upregulated lncRNA, LINC00483 was selected for further investigation to determine its functions in PDAC. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to confirm LINC00483 level in PDAC. PDAC cell lines were transfected with short hairpin RNA (shRNA) or microRNA (miRNA). 5-ethynyl-2'-deoxyuridine (EdU) assay, colony formation assay, wound healing assay, transwell assay, and xenograft mouse models were used to evaluate LINC00483 inhibition in vitro and in vivo. Luciferase reporter assay was performed to confirm binding sites of LINC00483 with miR-19a-3p, and miR-19a-3p with TANK-binding kinase 1 (TBK1). Immunohistochemistry (IHC) was performed to evaluate TBK1 and c-myc expression in PDAC tissues. Western blot was used to elucidate the LINC00483/miR-19a-3p/TBK1/mitogen-activated protein kinase (MAPK) axis. Results: Our data showed that LINC00483 was significantly upregulated in PDAC compared to normal tissue. High level of LINC00483 was correlated with advanced clinical stage, tumor invasion and metastasis, and adverse prognosis in PDAC patients. LINC00483 suppression inhibited proliferation and invasion in vitro and tumor development in vivo via modulation of miR-19a-3p expression. Subsequently, we found that miR-19a-3p binds to TBK1 in PDAC and LINC00483 could regulate PDAC cell progression by regulating miR-19a-3p via the TBK1/MAPK pathway. Conclusions: The results of our study suggested that the LINC00483/miR-19a-3p/TBK1/MAPK axis contributed to PDAC progression, which provides a potential therapeutic target for PDAC treatment.

Modelling of C-terminal tail of human STING and its interaction with tank-binding kinase 1.

Stimulator of interferon genes (STING) plays a significant role in a cell's intracellular defense against pathogens or self-DNA by inducing inflammation or apoptosis through a pathway known as cGAS-cGAMP-STING. STING uses one of its domains, the C-terminal tail (CTT) to recruit the members of the pathway. However, the structure of this domain has not been solved experimentally. STING conformation is open and more flexible when inactive. When STING gets activated by cGAMP, its conformation changes to a closed state covered by 4 beta-sheets over the binding site. This conformational change leads to its binding to Tank-binding kinase 1 (TBK1). TBK1 then phosphorylates STING aiding its entry to the cell's nucleus. In this study, we focused on the loop modeling of the CTT domain in both the active and inactive STING conformations. After the modeling step, the active and inactive STING structures were docked to one of the cGAS-cGAMP-STING pathway members, TBK1, to observe the differences of binding modes. CTT loop stayed higher in the active structure, while all the best-scored models, active or inactive, ended up around the same position with respect to TBK1. However, when the STING poses are compared with the cryo-EM image of the complex structure, the models in the active structure chain B displayed closer results to the complex structure.

Choosing Kinase Inhibitors for Androgen Deprivation Therapy-Resistant Prostate Cancer.

Androgen deprivation therapy (ADT) is a systemic therapy for advanced prostate cancer (PCa). Although most patients initially respond to ADT, almost all cancers eventually develop castration resistance. Castration-resistant PCa (CRPC) is associated with a very poor prognosis, and the treatment of which is a serious clinical challenge. Accumulating evidence suggests that abnormal expression and activation of various kinases are associated with the emergence and maintenance of CRPC. Many efforts have been made to develop small molecule inhibitors to target the key kinases in CRPC. These inhibitors are designed to suppress the kinase activity or interrupt kinase-mediated signal pathways that are associated with PCa androgen-independent (AI) growth and CRPC development. In this review, we briefly summarize the roles of the kinases that are abnormally expressed and/or activated in CRPC and the recent advances in the development of small molecule inhibitors that target kinases for the treatment of CRPC.

TANK-Binding Kinase 1 Regulates the Localization of Acyl-CoA Synthetase ACSL1 to Control Hepatic Fatty Acid Oxidation.

Hepatic TANK (TRAF family member associated NFκB activator)-binding kinase 1 (TBK1) activity is increased during obesity, and administration of a TBK1 inhibitor reduces fatty liver. Surprisingly, liver-specific TBK1 knockout in mice produces fatty liver by reducing fatty acid oxidation. TBK1 functions as a scaffolding protein to localize acyl-CoA synthetase long-chain family member 1 (ACSL1) to mitochondria, which generates acyl-CoAs that are channeled for ß-oxidation. TBK1 is induced during fasting and maintained in the unphosphorylated, inactive state, enabling its high affinity binding to ACSL1 in mitochondria. In TBK1-deficient liver, ACSL1 is shifted to the endoplasmic reticulum to promote fatty acid re-esterification in lieu of oxidation in response to fasting, which accelerates hepatic lipid accumulation. The impaired fatty acid oxidation in TBK1-deficient hepatocytes is rescued by the expression of kinase-dead TBK1. Thus, TBK1 operates as a rheostat to direct the fate of fatty acids in hepatocytes, supporting oxidation when inactive during fasting and promoting re-esterification when activated during obesity.

E3 ubiquitin ligase ASB8 negatively regulates interferon via regulating TBK1/IKKi homeostasis.

Cells recognize virus nucleic acid by pattern recognition receptors (PRRs), virus involve in the activation of signaling cascade of variable adaptor proteins, TANK-binding kinase1(TBK1)/ inhibitor of nuclear factor kappa-B kinase subunit epsilon(IKKi) complex, IκB kinase(IKKs) to trigger activation of transcription factor, interferon regulatory factor 3/7(IRF3/7), ultimately, leading to the production of type I interferon and exert anti-viral effects. In this study, E3 ubiquitin ligase ankyrin repeat and SOCS box-containing 8(ASB8) interacted with TBK1/IKKi and phosphorylation modification of ASB8 at site of Ser17 to further strengthen its ubiquitination activity were verified. Conversely, phosphorylated ASB8 accelerate K48-linked ubiquitination and degradation of TBK1/IKKi, which further reduces phosphorylation level of IRF3 and inhibits production of IFN-ß. At the same time, a new bridge molecule Leucine-rich repeat containing protein 10B(LRRC10B) upregulated after viral infection are involved in the formation and interaction with ASB8-TBK1/IKKi complex was reported. Our study reveals a new mechanism of ubiquitin ligase ASB8 modulating antiviral innate immunity by altering stability of TBK1/IKKi kinase complex.

Inosine:A broad-spectrum anti-inflammatory against SARS-CoV-2 infection-induced acute lung injury via suppressing TBK1 phosphorylation / 药物分析学报

Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)-induced cytokine storms constitute the primary cause of coronavirus disease 19(COVID-19)progression,severity,criticality,and death.Gluco-corticoid and anti-cytokine therapies are frequently administered to treat COVID-19,but have limited clinical efficacy in severe and critical cases.Nevertheless,the weaknesses of these treatment modalities have prompted the development of anti-inflammatory therapy against this infection.We found that the broad-spectrum anti-inflammatory agent inosine downregulated proinflammatory interleukin(IL)-6,upregulated anti-inflammatory IL-10,and ameliorated acute inflammatory lung injury caused by mul-tiple infectious agents.Inosine significantly improved survival in mice infected with SARS-CoV-2.It indirectly impeded TANK-binding kinase 1(TBK1)phosphorylation by binding stimulator of interferon genes(STING)and glycogen synthase kinase-3β(GSK3β),inhibited the activation and nuclear trans-location of the downstream transcription factors interferon regulatory factor(IRF3)and nuclear factor kappa B(NF-κB),and downregulated IL-6 in the sera and lung tissues of mice infected with lipopoly-saccharide(LPS),H1N1,or SARS-CoV-2.Thus,inosine administration is feasible for clinical anti-inflammatory therapy against severe and critical COVID-19.Moreover,targeting TBK1 is a promising strategy for inhibiting cytokine storms and mitigating acute inflammatory lung injury induced by SARS-CoV-2 and other infectious agents.

Effect Mechanism of Modified Baitouwengtang Treating Colorectal Cancer by Regulating CSF1R/STING/TBK1 Signaling to Polarize Phenotype of Tumor-associated Macrophages （TAMs） / 中国实验方剂学杂志

ObjectiveThis study aims to investigate the effect of modified Baitouwengtang （MBTWD） on tumor growth and the number of tumor-associated macrophages （TAMs） in tumor tissue of MC38 cell tumor-bearing mice with colorectal cancer and explores whether MBTWD mediates the remodeling of TAM phenotype to play an immunologically antitumor effect. MethodFirstly， The C57BL/6 mouse tumor model grafted subcutaneously was established， and then model mice were classified into a model group， positive control group（3 mg·kg-1）， and MBTWD groups with high and low dosages（23.43、46.86 g·kg-1）， with 10 mice in each group. In addition， 10 healthy mice were set as the blank group， and the changes in body weight， tumor volume， and survival status of mice in each group were observed. Tumor tissue， spleen， and peripheral blood were collected to calculate the tumor volume change， tumor inhibition rate， and spleen mass. Hematoxylin-eosin （HE） staining was used to observe the morphological changes of tumor tissue， and an immunofluorescence assay was used to detect the expression levels of CD4， CD8， and CD206 in tumor tissues of tumor-bearing mice. The secretion levels of transforming growth factor （TGF）-β， interleukin （IL）-6， and chemokine （C-C Motif） ligand 2 （CCL2） in peripheral serum were measured by using enzyme-linked immunosorbent assay （ELISA）. Secondly， a co-culture model induced by IL-4 in vitro of MC38 cells and murine monocytic macrophage RAW264.7 cells was established. Cell proliferation and activity assay （CCK-8） was used to detect the inhibitory effect of MBTWD containing serum on cell proliferation. A transwell experiment was used to detect the effect of IL-4-induced M2 macrophages on the invasion of MC38 cells. Flow cytometry was used to detect the expression of CD86 on the membrane of M2 macrophages induced by IL-4 with MBTWD containing serum. Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） was used to detect the effect of MBTWD containing serum on the mRNA expression levels of M1 macrophage-related polarization factors CD86， nitric oxide synthase （iNOS）， and IL-12， as well as M2 macrophage-related polarization factors CD206， CD163， and IL-10 after co-cultivation. Finally， the protein expression levels of colony-stimulating factor 1 receptor （CSF1R）， stimulator of interferon genes （STING）， and TANK binding kinase 1 （TBK1） in tumor tissues of tumor-bearing mice were detected by Western blot. ResultIn vivo experimental results show that compared with the model group， the MBTWD can significantly inhibit the tumor growth of tumor-bearing mice. Immunofluorescence experiments show that the MBTWD can increase the number of CD8+ T cell infiltration in tumor tissue of tumor-bearing mice， reduce the number of CD206+ TAMs infiltration， and down-regulate the secretion levels of cytokines IL-6， TGF-β， and CCL2 in peripheral blood of tumor-bearing mice. The results of in vitro experiments show that the MBTWD containing serum has no obvious inhibitory effect on cell proliferation， but the cell supernatant after co-cultivation with RAW264.7 cells can inhibit the proliferation activity of MC38 cells， and the invasion ability of MC38 cells is enhanced by IL-4-induced M2 macrophages. However， this effect can be inhibited in a concentration-dependent manner by the MBTWD containing serum. At the same time， the results of Real-time PCR show that the MBTWD containing serum can up-regulate the mRNA expression levels of M1 macrophage-related polarization factors CD86， iNOS， and IL-12 and down-regulate those of M2 macrophage-related polarization factors CD206， CD163， and IL-10. Flow cytometry results also confirm that the MBTWD containing serum can increase the number of repolarized CD86+ M1 macrophages， indicating that MBTWD can induce M2 macrophages to repolarized M1 macrophages to play an anti-tumor growth role. Finally， Western blot results show that MBTWD can down-regulate the expression of CSF1R protein and up-regulate that of STING and TBK1 proteins in tumor tissue of tumor-bearing mice. ConclusionMBTWD can down-regulate the infiltration number of CD206+ TAMs and increase the infiltration of CD8+ T cells， thereby playing an immunologically antitumor effect on the growth inhibition of colorectal cancer， which may be related to regulating CSF1R signaling and then activating STING/TBK1 signaling pathway to induce phenotypic remodeling of TAMs.