Identification of a role for TRIM29 in the control of innate immunity in the respiratory tract.
ABSTRACT: The respiratory tract is heavily populated with innate immune cells, but the mechanisms that control such cells are poorly defined. Here we found that the E3 ubiquitin ligase TRIM29 was a selective regulator of the activation of alveolar macrophages, the expression of type I interferons and the production of proinflammatory cytokines in the lungs. We found that deletion of TRIM29 enhanced macrophage production of type I interferons and protected mice from infection with influenza virus, while challenge of Trim29-/- mice with Haemophilus influenzae resulted in lethal lung inflammation due to massive production of proinflammatory cytokines by macrophages. Mechanistically, we demonstrated that TRIM29 inhibited interferon-regulatory factors and signaling via the transcription factor NF-?B by degrading the adaptor NEMO and that TRIM29 directly bound NEMO and subsequently induced its ubiquitination and proteolytic degradation. These data identify TRIM29 as a key negative regulator of alveolar macrophages and might have important clinical implications for local immunity and immunopathology.
Project description:Innate immune system is armed by several lines of pattern recognition receptors to sense various viral infection and to initiate antiviral immune response. This process is under a tight control and the negative feedback induced by infection and/or inflammation is critical to maintain immune homoeostasis and to prevent autoimmune disorders, however, the molecular mechanism is not fully understood. Here we report TRIM29, a ubiquitin E3 ligase, functions as an inducible negative regulator of innate immune response triggered by DNA virus and cytosolic DNA. DNA virus and cytosolic DNA stimulation induce TRIM29 expression robustly in macrophages and dendritic cells, although the basal level of TRIM29 is undetectable in those cells. TRIM29 deficiency elevates IFN-I and proinflammatory cytokine production upon viral DNA and cytosolic dsDNA stimulation. Consistently, in vivo experiments show that TRIM29-deficient mice are more resistant to HSV-1 infection than WT controls, indicated by better survival rate and reduced viral load in organs. Mechanism studies suggest that STING-TBK1-IRF3 signaling pathway in TRIM29 KO cells is significantly enhanced and the degradation of STING is impaired. Furthermore, we identify that TRIM29 targets STING for K48 ubiquitination and degradation. This study reveals TRIM29 as a crucial negative regulator in immune response to DNA virus and cytosolic DNA, preventing potential damage caused by overcommitted immune responses.
Project description:NK cells play an important role in immune surveillance and protective immunity, mainly through rapid cytokine release and cytolytic activities. But how such responses are negatively regulated remains poorly defined. In this study, we demonstrated that the E3 ubiquitin ligase TRIM29 is a crucial regulator of NK cell functions. We found that TRIM29 was not expressed in resting NK cells, but was readily upregulated following activation, especially after IL-12 plus IL-18 stimulation. The levels of TRIM29 expression were inversely correlated with IFN-? production by NK cells, suggesting that TRIM29 inhibits NK cell functions. Indeed, deficiency of TRIM29, specifically in NK cells, resulted in an enhanced IFN-? production and consequently protected mice from murine CMV infection. Mechanistically, we showed that once induced in NK cells, TRIM29 ubiquitinates and degrades the TGF-?-activated kinase 1 binding protein 2 (TAB2), a key adaptor protein in IFN-? production by NK cells. These results identify TRIM29 as a negative regulator of NK cell functions and may have important clinical implications.
Project description:Porcine reproductive and respiratory syndrome virus (PRRSV) is a highly infectious pathogen that causes severe diseases in pigs and great economic losses to the swine industry worldwide. Type I interferons (IFNs) play a crucial role in antiviral immunity. In the present study, we demonstrated that infection with the highly pathogenic PRRSV strain JXwn06 antagonized type I IFN expression induced by poly(I·C) in both porcine alveolar macrophages (PAMs) and blood monocyte-derived macrophages (BMo). Subsequently, we showed that the inhibition of poly(I·C)-induced IFN-? production by PRRSV was dependent on the blocking of NF-?B signaling pathways. By screening PRRSV nonstructural and structural proteins, we demonstrated that nonstructural protein 4 (nsp4), a viral 3C-like serine protease, significantly suppressed IFN-? expression. Moreover, we verified that nsp4 inhibited NF-?B activation induced by signaling molecules, including RIG-I, VISA, TRIF, and IKK?. nsp4 was shown to target the NF-?B essential modulator (NEMO) at the E349-S350 site to mediate its cleavage. Importantly, nsp4 mutants with defective protease activity abolished its ability to cleave NEMO and inhibit IFN-? production. These findings might have implications for our understanding of PRRSV pathogenesis and its mechanisms for evading the host immune response.Porcine reproductive and respiratory syndrome virus (PRRSV) is a major agent of respiratory diseases in pigs. Like many other viruses, PRRSV has evolved a variety of strategies to evade host antiviral innate immunity for survival and propagation. In this study, we show that PRRSV nsp4 is a novel antagonist of the NF-?B signaling pathway, which is responsible for regulating the expression of type I interferons and other crucial cytokines. We then investigated the underlying mechanism used by nsp4 to suppress NF-?B-mediated IFN-? production. We found that nsp4 interfered with the NF-?B signaling pathway through the cleavage of NEMO (a key regulator of NF-?B signaling) at the E349-S350 site, leading to the downregulation of IFN-? production induced by poly(I·C). The data presented here may help us to better understand PRRSV pathogenesis.
Project description:Many double-stranded DNA viruses, such as Epstein-Barr virus, can establish persistent infection, but the underlying virus-host interactions remain poorly understood. Here we report that in human airway epithelial cells Epstein-Barr virus induces TRIM29, a member of the TRIM family of proteins, to inhibit innate immune activation. Knockdown of TRIM29 in airway epithelial cells enhances type I interferon production, and in human nasopharyngeal carcinoma cells results in almost complete Epstein-Barr virus clearance. TRIM29 is also highly induced by cytosolic double-stranded DNA in myeloid dendritic cells. TRIM29 -/- mice have lower adenovirus titers in the lung, and are resistant to lethal herpes simplex virus-1 infection due to enhanced production of type I interferon. Mechanistically, TRIM29 induces K48-linked ubiquitination of Stimulator of interferon genes, a key adaptor in double-stranded DNA-sensing pathway, followed by its rapid degradation. These data demonstrate that Epstein-Barr virus and possible other double-stranded DNA viruses use TRIM29 to suppress local innate immunity, leading to the persistence of DNA virus infections.Proteins of the TRIM family have regulatory functions in immune signaling, often via ubiquitination of target proteins. Here, the authors show that TRIM29 is induced upon infection with DNA viruses, resulting in degradation of STING, decreased interferon signaling and increased pathogenicity in mice.
Project description:The innate immunity is critically important in protection against virus infections, and in the case of RNA viral infections, the signaling mechanisms that initiate robust protective innate immunity without triggering autoimmune inflammation remain incompletely defined. In this study, we found the E3 ligase TRIM29 was specifically expressed in poly I:C-stimulated human myeloid dendritic cells. The induced TRIM29 played a negative role in type I IFN production in response to poly I:C or dsRNA virus reovirus infection. Importantly, the challenge of wild-type mice with reovirus led to lethal infection. In contrast, deletion of TRIM29 protected the mice from this developing lethality. Additionally, TRIM29-/- mice have lower titers of reovirus in the heart, intestine, spleen, liver, and brain because of elevated production of type I IFN. Mechanistically, TRIM29 was shown to interact with MAVS and subsequently induce its K11-linked ubiquitination and degradation. Taken together, TRIM29 regulates negatively the host innate immune response to RNA virus, which could be employed by RNA viruses for viral pathogenesis.
2018-01-01 | S-EPMC6092021 | BioStudies
Project description:Respiratory infections, like the current COVID-19 pandemic, target epithelial cells in the respiratory tract. Alveolar macrophages (AMs) are tissue-resident macrophages located within the lung. They play a key role in the early phases of an immune response to respiratory viruses. AMs are likely the first immune cells to encounter SARS-CoV-2 during an infection and their reaction to the virus will have a profound impact on the outcome of the infection. Interferons (IFNs) are antiviral cytokines and among the first cytokines produced upon viral infection. In this study, AMs from non-infectious donors are challenged with SARS-CoV-2. We demonstrate that challenged AMs are incapable of sensing SARS-CoV-2 and of producing an IFN response in contrast to other respiratory viruses, like influenza A virus and Sendai virus, which trigger a robust IFN response. The absence of IFN production in AMs upon challenge with SARS-CoV2 could explain the initial asymptotic phase observed during COVID-19 and argues against AMs being the sources of proinflammatory cytokines later during infection.
Project description:BACKGROUND AND AIM: Tripartite motif-containing 29 (TRIM29) is structurally a member of the tripartite motif family of proteins and is involved in diverse human cancers. However, its role in pancreatic cancer remains unclear. METHODS: The expression pattern of TRIM29 in pancreatic ductal adenocarcinoma was assessed by immunocytochemistry. Multivariate logistic regression analysis was used to investigate the association between TRIM29 and clinical characteristics. In vitro analyses by scratch wound healing assay and invasion assays were performed using the pancreatic cancer cell lines. RESULTS: Immunohistochemical analysis showed TRIM29 expression in pancreatic cancer tissues was significantly higher??(n = 186) than that in matched adjacent nontumor tissues. TRIM29 protein expression was significantly correlated with lymph node metastasis (P = 0.019). Patients with positive TRIM29 expression showed both shorter overall survival and shorter recurrence-free survival than those with negative TRIM29 expression. Multivariate analysis revealed that TRIM29 was an independent factor for pancreatic cancer over survival (HR = 2.180, 95% CI: 1.324-4.198, P = 0.011). In vitro, TRIM29 knockdown resulted in inhibition of pancreatic cancer cell proliferation, migration, and invasion. CONCLUSIONS: Our results indicate that TRIM29 promotes tumor progression and may be a novel prognostic marker for pancreatic ductal adenocarcinoma.
Project description:TRIM29 (ATDC) exhibits a contextual function in cancer, but seems to exert a tumor-suppressor role in breast cancer. Here, we show that TRIM29 is often silenced in primary breast tumors and cultured tumor cells as a result of aberrant gene hypermethylation. RNAi-mediated silencing of TRIM29 in breast tumor cells increased their motility, invasiveness, and proliferation in a manner associated with increased expression of mesenchymal markers (N-cadherin and vimentin), decreased expression of epithelial markers (E-cadherin and EpCAM), and increased expression and activity of the oncogenic transcription factor TWIST1, an important driver of the epithelial-mesenchymal transition (EMT). Functional investigations revealed an inverse relationship in the expression of TRIM29 and TWIST1, suggesting the existence of a negative regulatory feedback loop. In support of this relationship, we found that TWIST1 inhibited TRIM29 promoter activity through direct binding to a region containing a cluster of consensus E-box elements, arguing that TWIST1 transcriptionally represses TRIM29 expression. Analysis of a public breast cancer gene-expression database indicated that reduced TRIM29 expression was associated with reduced relapse-free survival, increased tumor size, grade, and metastatic characteristics. Taken together, our results suggest that TRIM29 acts as a tumor suppressor in breast cancer through its ability to inhibit TWIST1 and suppress EMT.
Project description:Obesity is associated with increased prevalence and severity of asthma. Adipose tissue macrophages can contribute to the systemic proinflammatory state associated with obesity. However, it remains unknown whether alveolar macrophages have a unique phenotype in overweight/obese patients with asthma.We hypothesized that leptin levels would be increased in the bronchoalveolar lavage fluid from overweight/obese subjects and, furthermore, that leptin would alter the response of alveolar macrophages to bacterial LPS.Forty-two subjects with asthma and 46 healthy control subjects underwent research bronchoscopy. Bronchoalveolar lavage fluid from 66 was analyzed for the level of cellular inflammation, cytokines, and soluble leptin. Cultured primary macrophages from 22 subjects were exposed to LPS, leptin, or leptin plus LPS. Cytokines were measured in the supernatants.Leptin levels were increased in overweight/obese subjects, regardless of asthma status (P = 0.013), but were significantly higher in overweight/obese subjects with asthma. Observed levels of tumor necrosis factor-? were highest in overweight/obese subjects with asthma. Ex vivo studies of primary alveolar macrophages indicated that the response to LPS was most robust in alveolar macrophages from overweight/obese subjects with asthma and that preexposure to high-dose leptin enhanced the proinflammatory response. Leptin alone was sufficient to induce production of proinflammatory cytokines from macrophages derived from overweight/obese subjects with asthma.Ex vivo studies indicate that alveolar macrophages derived from overweight/obese subjects with asthma are uniquely sensitive to leptin. This macrophage phenotype, in the context of higher levels of soluble leptin, may contribute to the pathogenesis of airway disease associated with obesity.
Project description:Transcriptional profiling of human normal-like breast cells MCF10A comparing control MCF10A cells transfected with a pLenti6/BLOCK-iT™-DEST vector with MCF10A cells transfected with a pLenti6/BLOCK-iT™-DEST vector containing TRIM29 shRNA targeting nucleotides 1265–1285 of the TRIM29 open reading frame (ORF, NM_012101). Transcriptional profiling of human breast cancer cells MCF7 comparing control MCF7 cells transfected with a pLenti6.2/N-LumioTM/V5-DEST vector with MCF7 cells transfected with a pLenti6.2/N-LumioTM/V5-DEST vector containing TRIM29 full-length cDNA (ORF, NM_012101). Two-condition experiment, MCF10A-vector control vs. MCF10A-TRIM29 shRNA cells; MCF7-vector control vs. MCF7-TRIM29 cells.