Cap-related modifications of RNA regulate binding to IFIT proteins.

All cells in our body are equipped with receptors to recognize pathogens and trigger a rapid defense response. As a result, foreign molecules are blocked and cells are alerted to the danger. Among the many molecules produced in response to viral infection are interferon-induced proteins with tetratricopeptide repeats (IFITs). Their role is to recognize foreign mRNA and eliminate it from the translational pool of transcripts. In the present study, we used biophysical methods to characterize the interactions between IFIT1 protein and its partners IFIT2 and IFIT3. IFIT1 interacts with IFIT3 with nanomolar binding affinity, which did not change significantly in the presence of the preformed IFIT2/3 complex. The interactions between IFIT2 and IFIT3 and IFIT1 and IFIT2 were one order of magnitude weaker. We also present kinetic data of the interactions between the IFIT protein complex and short RNA bearing various modifications at the 5' end. We show kinetic parameters for interaction between IFIT complex and RNA with m6Am modification. The results show that the cap adjacent m6Am modification is a stronger signature than cap1 alone. It blocks the formation of a complex between IFIT proteins and m7Gpppm6Am-RNA much more effectively than other cap modifications. In contrast, m6A in the 5'UTR is not recognized by IFIT proteins and does not contribute to translation repression by IFIT proteins. The data obtained are important for understanding the regulation of expression of genetic information. They indicate that 2'-O and m6Am modifications modulate the availability of mRNA molecules for proteins of innate immune response.

Goose IFIT5 positively regulates goose astrovirus replication in GEF cells.

Interferon-induced protein with tetratricopeptide repeats (IFITs), a family of proteins strongly induced by type I interferon (IFN-I), are deeply involved in many cellular and viral processes. IFIT5, the sole protein in this family found in birds, also plays a crucial role in regulating virus infection. In this study, goose IFIT5 (gIFIT5) was first cloned from peripheral blood lymphocyte (PBL) and phylogenetic analysis showed that it was highly homologous with duck IFIT5 (dIFIT5), sharing 94.6% identity in amino acid sequence. Subsequently, the expression kinetics of gIFIT5 during goose astrovirus (GAstV) infection and the regulatory effect of gIFIT5 on GAstV proliferation were evaluated. Results showed that the mRNA and protein expression level of gIFIT5 was greatly induced by GAstV infection, especially at 12 hpi. Importantly, gIFIT5 could conversely promote GAstV replication in GEF cells. Virus titers in gIFIT5 overexpression group were significantly higher than those in control group at 12 and 24 hpi. Western blot and quantitative real-time PCR (qRT-PCR) further demonstrated that the production of viral cap protein was significantly facilitated in gIFIT5-transfected group. Collectively, GAstV facilitates self-replication via promoting gIFIT5 expression.

diABZI and poly(I:C) inhibit osteoclastic bone resorption by inducing IRF7 and IFIT3.

Type I interferons (IFN-I) are pleiotropic factors endowed with multiple activities that play important roles in innate and adaptive immunity. Although many studies indicate IFN-I inducers exert favorable effects on broad-spectrum antivirus, immunomodulation, and anti-tumor by inducing endogenous IFN-I and IFN-stimulated genes (ISGs), their function in bone homeostasis still needs further exploration. Here, our study demonstrates two distinct IFN-I inducers, diABZI and poly(I:C), as potential therapeutics to alleviate osteolysis and osteoporosis. Firstly, IFN-I inducers suppress the genes that control osteoclast (OC) differentiation and activity in vitro. Moreover, diABZI alleviates bone loss in Ti particle-induced osteolysis and ovariectomized (OVX)-induced osteoporosis in vivo by inhibiting OC differentiation and function. In addition, the inhibitory effects of IFN-I inducers on OC differentiation are not observed in macrophages derived from Ifnar1-/- mice, which indicate that the suppressive effect of IFN-I inducers on OC is IFNAR-dependent. Mechanistically, RNAi-mediated silencing of IRF7 and IFIT3 in OC precursors impair the suppressive effect of the IFN-I inducers on OC differentiation. Taken together, these results demonstrate that IFN-I inducers play a protective role in bone turnover by limiting osteoclastogenesis and bone resorption through the induction of OC-specific mediators via the IFN-ß signaling pathway.

The Role of Interferon-Induced Proteins with Tetratricopeptide Repeats 1 and 2 in Sepsis-Induced Acute Liver Injury.

Background: Sepsis refers to a life-threatening organ dysfunction which can be resulted from the infection-induced dysregulated host response. A large number of inflammatory cytokines are released to act on the liver, making the liver one of the common target organs for the development of multiple organ dysfunction syndrome (MODS) in patients with sepsis. Sepsis-induced acute liver injury (SALI) can aggravate systemic disease. As a result, it is of great clinical significance to comprehend the molecular biological mechanism of SALI and to identify the markers for evaluating SALI. Interferon-induced proteins with tetratricopeptide repeats 1 and 2 (IFIT1, IFIT2) have been recognized as the anti-inflammatory factors that are widely expressed in various organs. The present study was aimed at clarifying the roles of IFIT1 and IFIT2 in the development of SALI. Methods: A two-sample Mendelian randomization (MR) analysis was employed. Summary statistics datas were obtained from GWAS for inflammatory factors [tumor necrosis factor (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6)], IFIT2, and sepsis as well as liver injury. Independent SNPs were selected as instrumental variables (IVs). Inverse variance weighted (IVW) in the MR analysis was adopted as the primary method for estimating the causal associations of inflammatory factors and IFIT2 with two diseases, and the associations of inflammatory factors with IFIT2. Additionally, weighted median method, MR-Egger and sensitivity analyses were applied in assessing the robustness of the results and ensure the result reliability. Subsequently, 119 healthy volunteers, 116 patients with sepsis and 116 SALI patients were recruited. The ELISA method was employed to quantify the expression levels of TNF-α, IL-1ß, and IL-6. Additionally, qRT-PCR was conducted to measure the expression of IFIT1 and IFIT2. Furthermore, the correlations of IFIT1 and IFIT2 with inflammatory factors, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were explored. Results: As shown by the MR analysis, the genetically predisposed sepsis was significantly associated with the risk of IL-1ß, with an odds ratio (OR) of 1.069 (95% confidence interval (CI), 1.015-1.127, p = 0.0119), and negatively associated with the risk of IL-6, with an OR of 0.880 (95% CI: 0.792-0.979, p= 0.0184). Meanwhile, there were positive causal effects of IL-6 (OR = 1.269, 95% CI: 1.032-1.561, p= 0.0238), IL-1ß (OR = 1.106, 95% CI: 1.010-1.211, p = 0.0299) and IFIT2 (OR = 1.191, 95% CI: 1.045-1.359, p = 0.0090) on liver injury. Additionally, there was a positive causal effect of IFIT2 (OR = 1.164, 95% CI: 1.035-1.309, p= 0.0110) on IL-1ß. Upon sensitivity analyses, there was weak evidence of such effects, indicating that the findings of this study were robust and reliable. Our results revealed the elevated levels of TNF-α, IL-1ß, and IL-6 in the blood samples of sepsis and SALI patients (p < 0.0001). Conversely, IFIT1 and IFIT2 demonstrated the significantly decreased levels in peripheral blood mononuclear cells (PBMCs) of SALI patients (p < 0.0001). Furthermore, the expression levels of IFIT1 and IFIT2 were both negatively correlated with ALT activity (r = -0.3426, p = 0.0002; r = -0.3069, p = 0.0008) and AST activity (r = -0.2483, p = 0.0072; r = -0.3261, p = 0.0004), respectively. Moreover, the expression of IFIT1 and IFIT2 was both negatively related to the levels of TNF-α (r = -0.5027, p < 0.0001; r = -0.4218, p < 0.0001), IL-1ß (r = -0.3349, p = 0.0002; r = -0.4070, p < 0.0001) and IL-6 (r = -0.2734, p = 0.0030; r = -0.3536, p < 0.0001), respectively. Conclusion: IFIT1 and IFIT2 can serve as the diagnostic markers for sepsis-related liver injury, and IFIT1 and IFIT2 may participate in the pathological process of sepsis-related liver injury by regulating inflammation and liver function.

IFIT1 + neutrophil is a causative factor of immunosuppressive features of poorly cohesive carcinoma (PCC).

The importance of the immune microenvironment in poorly cohesive carcinoma (PCC) has been highlighted due to its limited response rate to conventional therapy and emerging treatment resistance. A combination of clinical cohorts, bioinformatics analyses, and functional/molecular experiments revealed that high infiltration of Interferon Induced Protein with Tetratricopeptide Repeats 1 (IFIT1) + tumor-associated neutrophils (TANs) is a distinguishing feature of PCC patients. Upregulation of IFIT1 + TANs promote migration and invasion of gastric cancer (GC) cell lines (MKN45 and MKN74) and stimulates the growth of cell-derived xenograft models. Besides, by promoting macrophage secreted phosphoprotein 1 (SPP1) expression and facilitating cancer-associated fibroblast and endothelial cell recruitment and activation through TANs, IFIT1 promotes a mesenchymal phenotype, which is associated with a poor prognosis. Importantly, compared to non-PCC (NPCC), PCC tumors is more immunosuppressive. Mechanistically, IFIT1 can be stimulated by IFN-γ and contributes to the expression of Programmed Cell Death 1 Ligand (PDL1) in TANs. We demonstrated in mouse models that IFIT1 + PDL1 + TANs can induce acquired resistance to anti-PD-1 immunotherapy, which may be responsible for the difficulty of PCC patients to benefit from immunotherapy. This work highlights the role of IFIT1 + TANs in mediating the remodeling of the tumor immune microenvironment and immunotherapeutic resistance and introduces IFIT1 + TANs as a promising target for precision therapy of PCC.

Characterization of an African swine fever virus outbreak in India and comparative analysis of immune genes in infected and surviving crossbreed vs. indigenous Doom pigs.

Since 2020, African swine fever (ASF) has affected all pig breeds in Northeast India except Doom pigs, a unique indigenous breed from Assam and the closest relatives of Indian wild pigs. ASF outbreaks result in significant economic losses for pig farmers in the region. Based on sequencing and phylogenetic analysis of the B646L (p72) gene, it has been determined that ASFV genotype II is responsible for outbreaks in this region. Recent studies have shown that MYD88, LDHB, and IFIT1, which are important genes of the immune system, are involved in the pathogenesis of ASFV. The differential expression patterns of these genes in surviving ASFV-infected and healthy Doom breed pigs were compared to healthy controls at different stages of infection. The ability of Doom pigs to withstand common pig diseases, along with their genetic resemblance to wild pigs, make them ideal candidates for studying tolerance to ASFV infection. In the present study, we investigated the natural resistance to ASF in Doom pigs from an endemic area in Northeast India. The results of this study provide important molecular insights into the regulation of ASFV tolerance genes.

Single-cell transcriptomics of blood identified IFIT1+ neutrophil subcluster expansion in NTM-PD patients.

OBJECTIVE: Non-tuberculous mycobacterial pulmonary disease (NTM-PD) is caused by an imbalance between pathogens and impaired host immune responses. Mycobacterium avium complex (MAC) and Mycobacterium abscessus (MAB) are the two major pathogens that cause NTM-PD. In this study, we sought to dissect the transcriptomes of peripheral blood immune cells at the single-cell resolution in NTM-PD patients and explore potential clinical markers for NTM-PD diagnosis and treatment. METHODS: Peripheral blood samples were collected from six NTM-PD patients, including three MAB-PD patients, three MAC-PD patients, and two healthy controls. We employed single-cell RNA sequencing (scRNA-seq) to define the transcriptomic landscape at a single-cell resolution. A comprehensive scRNA-seq analysis was performed, and flow cytometry was conducted to validate the results of scRNA-seq. RESULTS: A total of 27,898 cells were analyzed. Nine T-cells, six mononuclear phagocytes (MPs), and four neutrophil subclusters were defined. During NTM infection, naïve T-cells were reduced, and effector T-cells increased. High cytotoxic activities were shown in T-cells of NTM-PD patients. The proportion of inflammatory and activated MPs subclusters was enriched in NTM-PD patients. Among neutrophil subclusters, an IFIT1+ neutrophil subcluster was expanded in NTM-PD compared to healthy controls. This suggests that IFIT1+ neutrophil subcluster might play an important role in host defense against NTM. Functional enrichment analysis of this subcluster suggested that it is related to interferon response. Cell-cell interaction analysis revealed enhanced CXCL8-CXCR1/2 interactions between the IFIT1+ neutrophil subcluster and NK cells, NKT cells, classical mononuclear phagocytes subcluster 1 (classical Mo1), classical mononuclear phagocytes subcluster 2 (classical Mo2) in NTM-PD patients compared to healthy controls. CONCLUSIONS: Our data revealed disease-specific immune cell subclusters and provided potential new targets of NTM-PD. Specific expansion of IFIT1+ neutrophil subclusters and the CXCL8-CXCR1/2 axis may be involved in the pathogenesis of NTM-PD. These insights may have implications for the diagnosis and treatment of NTM-PD.

The interferon-induced protein, IFIT2, requires RNA-binding activity and neuronal expression to protect mice from intranasal vesicular stomatitis virus infection.

The interferon (IFN) system protects mammals from diseases caused by virus infections. IFN synthesis is induced by pattern recognition receptor signaling pathways activated by virus infection. IFN is secreted from the infected cells and acts upon neighboring cells by binding cell surface receptors and triggering induction of hundreds of IFN-stimulated genes and proteins, many of which block different steps of virus replication. The IFN-induced tetratricopeptide repeat proteins (IFIT) are a family of RNA-binding proteins. We and others have previously reported that IFIT2 protects mice from many neurotropic RNA viruses; indeed, Ifit2-/- mice are very susceptible to intranasal or subcutaneous infections with vesicular stomatitis virus (VSV). Here, using a newly generated conditional knockout mouse, we report that ablation of Ifit2 expression only in neuronal cells was sufficient to render mice susceptible to neuropathogenesis caused by intranasal, but not subcutaneous, infection of VSV. Another genetically modified mouse line, expressing a mutant IFIT2 that cannot bind RNA, was as susceptible to VSV infection as Ifit2-/- mice. These results demonstrated that IFIT2 RNA-binding activity is essential for protecting mice against neurological diseases caused by intranasal infection of VSV.IMPORTANCEInterferon's (IFN's) antiviral effects are mediated by the proteins encoded by the interferon-stimulated genes. IFN-stimulated genes (IFIT2) is one such protein, which inhibits replication of many RNA viruses in the mouse brain and the resultant neuropathology. Our study sheds light on how IFIT2 works. By ablating Ifit2 expression only in neuronal cells, using a newly generated conditional knockout mouse line, we showed that Ifit2 induction in the neurons of the infected mouse was necessary for antiviral function of interferon. IFIT2 has no known enzyme activity; instead, it functions by binding to cellular or viral proteins or RNAs. We engineered a new mouse line that expressed a mutant IFIT2 that cannot bind RNA. These mice were very susceptible to infection with vesicular stomatitis virus indicating that the RNA-binding property of IFIT2 was essential for its antiviral function in vivo.

WGCNA and machine learning analysis identifi ed SAMD9 and IFIT3 as primary Sjögren's Syndrome key genes.

Background: Current treatments for primary Sjögren's Syndrome (pSS) are with limited effect, partially due to the heterogeneity and uncleared mechanism. Methods: We got GSE40568 (Japan) and GSE40611 (USA), and analyzed them with WGCNA to find key Differentially expressed genes (DEGs) between pSS and healthy salivary glands (SG). Key pSS genes (KPGs) were further selected through 3 machine-learning methods. The expression of KPGs was validated via two other GEO datasets (GSE127952 and GSE154926). Infiltrated immune cells, ceRNA network, and potential compounds were explored. Results: Our study identified 376 DEGs from the pSS patients, with 186 genes located in the "plum2" module, showing the strongest correlation with clinical characteristics. SAMD9 and IFIT3 emerged as KPGs with excellent diagnostic potential. SAMD9 demonstrated close association with immune cell infiltration. We constructed a lncRNA-miRNA-mRNA network comprising 2 KPGs, 12 miRNAs, 124 lncRNAs, and potential therapeutic targets. Conclusion: In the investigation of pSS public datasets, our study revealed two potential critical mediators in the pathological process of pSS salivary glands, namely SAMD9 and IFIT3. Furthermore, we put forth a hypothesis regarding the ceRNA network and made predictions regarding potential therapeutic drugs targeting these two genes.

A bioinformatics approach to systematically analyze the molecular patterns of monkeypox virus-host cell interactions.

Monkeypox has been spreading worldwide since May 2022, when the World Health Organization (WHO) declared the outbreak a "public health emergency of international concern." The spread of monkeypox has posed a serious threat to the health of people around the world, but few studies have been conducted, and the molecular mechanism of monkeypox after infection remains unclear. We therefore implemented a transcriptome analysis to identify signaling pathways and biomarkers in monkeypox-infected cells to help understand monkeypox-host cell interactions. In this study, datasets GSE36854 and GSE11234 were obtained from GEO. Of these, 84 significantly different genes were identified in the dataset GSE36854, followed by KEGG, GO analysis protein-protein interaction (PPI) construction, and Hub gene extraction. We also analyzed the expression regulation of hub genes and screened for drugs targeting hub genes. The results showed that monkeypox-infected cells significantly activated the cellular immune response. The top 10 hub genes are IER3, IFIT2, IL11, ZC3H12A, EREG, IER2, NFKBIE, FST, IFIT1 and AREG. AP-26113 and itraconazole can be used to counteract the inhibitory effect of monkeypox on IFIT1 and IFIT2 and serve as candidate drugs for the treatment of monkeypox virus infection. IRF1 may also be a transcription factor of IFIT. Our results provide a new entry point for understanding how monkeypox virus interacts with its host.

IFIT1 modulates the proliferation, migration and invasion of pancreatic cancer cells via Wnt/ß-catenin signaling.

OBJECTIVES: Previously, Interferon-induced Protein with Tetratricopeptide Repeats 1 (IFIT1) has been shown to promote cancer development. Here, we aimed to explore the role of IFIT1 in the development and progression of pancreatic cancer, including the underlying mechanisms. METHODS: We explored IFIT1 expression in pancreatic cancer samples using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. Cell Counting Kit-8 (CCK8), colony formation, scratch wound-healing and Transwell assays were performed to assess the proliferation, migration and invasion abilities of pancreatic cancer cells. Gene Set Enrichment Analysis (GSEA) and Western blotting were performed to assess the regulatory effect of IFIT1 on the Wnt/ß-catenin pathway. RESULTS: We found that upregulation of IFIT1 expression is common in pancreatic cancer and is negatively associated with overall patient survival. Knockdown of IFIT1 expression led to decreased proliferation, migration and invasion of pancreatic cancer cells. We also found that IFIT1 could regulate Wnt/ß-catenin signaling, and that a Wnt/ß-catenin agonist could reverse this effect. In addition, we found that IFIT1 can promote epithelial-mesenchymal transition (EMT) of pancreatic cancer cells. CONCLUSIONS: Our data indicate that IFIT1 increases pancreatic cancer cell proliferation, migration and invasion by activating the Wnt/ß-catenin pathway. In addition, we found that EMT could be regulated by IFIT1. IFIT1 may serve as a potential therapeutic target for pancreatic cancer.

Interferon-induced protein with tetratricopeptide repeats 5 of black fruit bat (Pteropus alecto) displays a broad inhibition of RNA viruses.

Bats are natural host reservoirs and have adapted a unique innate immune system that permits them to host many viruses without exhibiting symptoms. Notably, bat interferon stimulated genes (ISGs) have been shown to play antiviral roles. Interferon induced protein with tetratricopeptide repeats 5 (IFIT5) is a well-characterised ISG in humans with antiviral activities against negative-sense RNA viruses via inhibiting viral transcription. Here, we aim to investigate if Pteropus alecto (pa) IFIT5 (paIFIT5) possess the ability to inhibit negative-sense RNA viruses. Initially, gene syntenic and comparative structural analyses of multiple animals highlighted a high level of similarity between Pteropus alecto and human IFIT5 proteins. Our results showed that paIFIT5 was significantly inducible by viral and dsRNA stimulation. Transient overexpression of paIFIT5 inhibited the replication of vesicular stomatitis virus (VSV). Using minireplicon and transcription reporter assays, we demonstrated the ability of paIFIT5 specifically to inhibit H17N10 polymerase activity. Mechanistically, we noticed that the antiviral potential of paIFIT5 against negative sense RNA viruses was retributed to its interaction with 5'ppp containing RNA. Taken together, these findings highlight the genetic and functional conservation of IFIT5 among mammals.

The molecular language of RNA 5' ends: guardians of RNA identity and immunity.

RNA caps are deposited at the 5' end of RNA polymerase II transcripts. This modification regulates several steps of gene expression, in addition to marking transcripts as self to enable the innate immune system to distinguish them from uncapped foreign RNAs, including those derived from viruses. Specialized immune sensors, such as RIG-I and IFITs, trigger antiviral responses upon recognition of uncapped cytoplasmic transcripts. Interestingly, uncapped transcripts can also be produced by mammalian hosts. For instance, 5'-triphosphate RNAs are generated by RNA polymerase III transcription, including tRNAs, Alu RNAs, or vault RNAs. These RNAs have emerged as key players of innate immunity, as they can be recognized by the antiviral sensors. Mechanisms that regulate the presence of 5'-triphosphates, such as 5'-end dephosphorylation or RNA editing, prevent immune recognition of endogenous RNAs and excessive inflammation. Here, we provide a comprehensive overview of the complexity of RNA cap structures and 5'-triphosphate RNAs, highlighting their roles in transcript identity, immune surveillance, and disease.

IFIT3 accelerates the progression of head and neck squamous cell carcinoma by targeting PD-L1 to activate PI3K/AKT signaling pathway.

BACKGROUND: Emerging evidence has shown interferon-induced protein with tetratricopeptide repeats 3 (IFIT3) may be predicted to be a candidate oncogene and involved in the onset and progression of cancer, but IFIT3's potential role in cancer, particularly in head and neck squamous cell carcinoma (HNSC), is not well recognized. This study aims to reveal the role of IFIT3 in HNSC and the underlying molecular mechanism. METHODS: Bioinformatics analysis, immunohistochemical staining, RT-PCR, and Western blotting analysis were used to detect IFIT3 expression in HNSC. CCK-8 assays, colony formation assays, wound-healing assays, transwell assays, and sphere formation were used to explore proliferative, migratory, and invasive activities and cancer stemness of HNSC cells after IFIT3 knockdown and over-expressed. The alterations of EMT markers and PI3K/AKT pathway were detected by Western blotting. Animal studies were performed to analyze the effect of IFIT3 on tumor growth and metastasis of HNSC in vivo. RESULTS: In this study, we observed that IFIT3 was highly expressed in HNSC, and its higher expression contributed to poorer survival of patients with clinical stage IV or grade 3. Function assay indicated that IFIT3 promoted malignant behaviors in vitro, as well as tumor growth and lung metastasis in vivo. Meanwhile, PD-L1 knockdown or over-expressed reversed cancer cell stemness, migration, invasion, and PI3K/AKT signaling pathway which were regulated by IFIT3. CONCLUSIONS: Our results reveal that IFIT3 promotes EMT and cancer stemness by targeting PD-L1 to activate PI3K/AKT signaling pathway in HNSC, and targeting IFIT3 may be a novel strategy for the treatment of patients with HNSC.

Knockdown of IFIT3 ameliorates multiple sclerosis via selectively regulating M1 polarization of microglia in an experimental autoimmune encephalomyelitis model.

The key to the treatment of multiple sclerosis (MS) is to promote the transition from inflammation-induced demyelination to remyelination. Polarization of microglia towards M1 or M2 phenotype is critical in this transition. Interferon induced protein with tetratricopeptide repeats 3 (IFIT3) is involved in inflammatory reaction and up-regulated in M1-polarized macrophages. However, its effect on microglia during MS has not been reported. In this paper, we demonstrated the important role of IFIT3 in selectively regulating microglia polarization. The expression of IFIT3 was increased when microglia were polarized towards M1, but did not change under M2 polarization. The knockdown of IFIT3 selectively inhibited M1 polarization, while M2 polarization was not affected by IFIT3 silencing. Furthermore, the activation of signal transducer and activator of transcription 1 (STAT1) and nuclear factor kappa-B (NF-ĸB) signaling in M1 polarized microglia was suppressed by downregulating IFIT3. In experimental autoimmune encephalitis (EAE) mice, an animal model of MS, IFIT3 expression was upregulated. The disease progression, inflammatory infiltration and demyelination in the EAE mice were alleviated by silencing IFIT3. The inhibitory effects of IFIT3 knockdown on M1 polarization and STAT1 and NF-ĸB pathways were also confirmed in the spinal cord of EAE mice. In summary, our findings suggest that IFIT3 selectively intensified microglia polarization towards the pro-inflammatory M1 phenotype, and may contribute to the progression of MS.

ETV7 promotes colorectal cancer progression through upregulation of IFIT3.

Members of the E26 transformation-specific (ETS) variant transcription factor family act as either tumor suppressors or oncogenic factors in numerous types of cancer. ETS variant transcription factor 7 (ETV7) participates in the development of malignant tumors, whereas its involvement in colorectal cancer (CRC) is less clear. In this study, The Cancer Genome Atlas (TCGA) and immunochemistry staining were applied to check the clinical relevance of ETV7 and interferon-induced protein with tetratricopeptide repeats 3 (IFIT3) in CRC patients. Overexpression and knockdown of ETV7 and IFIT3 were conducted by transfecting the cells with pCDNA3.1 plasmids and siRNAs, respectively. Western blotting was used to detect the protein expression of ETV7 in CRC cells. Cell Counting Kit-8, cell colony formation, and Transwell assays, as well as flow cytometry, were used to evaluate the proliferation, migration, cell cycle, and apoptosis of CRC cells. Furthermore, western blotting, RT-qPCR, and luciferase assay were used to explore the regulation of ETV7 on IFIT3. Rescue assay was used to investigate the significance of ETV7/IFIT3 axis on CRC progression. We found that ETV7 was upregulated in CRC tissues and cells. Overexpression of ETV7 stimulated the proliferation, migration, and cell cycle amplification, and reduced the apoptosis of CRC cells. Downregulation of ETV7 exerted the opposite effect on CRC cell progression. Moreover, we demonstrated that ETV7 stimulated the transcription activity, the mRNA and protein expression of IFIT3 in CRC cells. There was a positive correlation between ETV7 and IFIT3 in CRC patients. IFIT3 knockdown reversed the promotive effect exerted by overexpression of ETV7 on the amplification and migration of CRC cells. By contrast, overexpression of IFIT3 blocked the inhibitory effect of ETV7-targeting siRNA. In summary, ETV7 induces progression of CRC by activating the transcriptional expression of IFIT3. The EVT7/IFIT3 axis may be a novel target for CRC therapy.

Porcine deltacoronavirus nsp5 antagonizes type I interferon signaling by cleaving IFIT3.

Porcine deltacoronavirus (PDCoV) has caused enormous economic losses to the global pig industry. However, the immune escape mechanism of PDCoV remains to be fully clarified. Transcriptomic analysis revealed a high abundance of interferon (IFN)-induced protein with tetratricopeptide repeats 3 (IFIT3) transcripts after PDCoV infection, which initially implied a correlation between IFIT3 and PDCoV. Further studies showed that PDCoV nsp5 could antagonize the host type I interferon signaling pathway by cleaving IFIT3. We demonstrated that PDCoV nsp5 cleaved porcine IFIT3 (pIFIT3) at Gln-406. Similar cleavage of endogenous IFIT3 has also been observed in PDCoV-infected cells. The pIFIT3-Q406A mutant was resistant to nsp5-mediated cleavage and exhibited a greater ability to inhibit PDCoV infection than wild-type pIFIT3. Furthermore, we found that cleavage of IFIT3 is a common characteristic of nsp5 proteins of human coronaviruses, albeit not alphacoronavirus. This finding suggests that the cleavage of IFIT3 is an important mechanism by which PDCoV nsp5 antagonizes IFN signaling. Our study provides new insights into the mechanisms by which PDCoV antagonizes the host innate immune response.IMPORTANCEPorcine deltacoronavirus (PDCoV) is a potential emerging zoonotic pathogen, and studies on the prevalence and pathogenesis of PDCoV are ongoing. The main protease (nsp5) of PDCoV provides an excellent target for antivirals due to its essential and conserved function in the viral replication cycle. Previous studies have revealed that nsp5 of PDCoV antagonizes type I interferon (IFN) production by targeting the interferon-stimulated genes. Here, we provide the first demonstration that nsp5 of PDCoV antagonizes IFN signaling by cleaving IFIT3, which affects the IFN response after PDCoV infection. Our findings reveal that PDCoV nsp5 is an important interferon antagonist and enhance the understanding of immune evasion by deltacoronaviruses.

NMI promotes tumor progression and gemcitabine resistance in pancreatic cancer via STAT3-IFIT3 axis.

N-myc and STAT interactor (NMI) has been reported to interact with several transcription factors, including STATs family, c-Myc, N-Myc, and BRCA1, to indirectly affect transcription events and participate in multiple cellular processes. However, its function in pancreatic ductal adenocarcinoma (PDAC) has seldom been studied. In this study, we investigated the regulation of NMI on PDAC progression and uncovered the underlying molecular mechanisms. We found that NMI expression was significantly upregulated in PDAC and high NMI expression was related to a worse patient survival. Cell proliferation and migration assay, including cell viability, transwell assay, wound healing, and subcutaneous mouse model were utilized to confirm the function of NMI in PDAC progression. Downregulation of NMI abrogates tumor progression of PDAC both in vitro and in vivo. RNA sequencing was utilized to identify the downstream molecules of NMI and interferon-induced protein with tetratricopeptide repeats 3 (IFIT3) was confirmed to be regulated by NMI in both mRNA and protein level. The binding function of NMI to STAT3 was essential in regulating the IFIT3 expression. Moreover, the NMI/STAT3-IFIT3 axis was identified to markedly facilitate the gemcitabine resistance in PDAC cells.

The CD40/CD40 ligand dyad and its downstream effector molecule ISG54 in relating acute neuroinflammation with persistent, progressive demyelination.

Although Multiple Sclerosis (MS) is primarily thought to be an autoimmune condition, its possible viral etiology must be taken into consideration. When mice are administered neurotropic viruses like mouse hepatitis virus MHV-A59, a murine coronavirus, or its isogenic recombinant strain RSA59, neuroinflammation along with demyelination are observed, which are some of the significant manifestations of MS. MHV-A59/RSA59 induced neuroinflammation is one of the best-studied experimental animal models to understand the viral-induced demyelination concurrent with axonal loss. In this experimental animal model, one of the major immune checkpoint regulators is the CD40-CD40L dyad, which helps in mediating both acute-innate, innate-adaptive, and chronic-adaptive immune responses. Hence, they are essential in reducing acute neuroinflammation and chronic progressive adaptive demyelination. While CD40 is expressed on antigen-presenting cells and endothelial cells, CD40L is expressed primarily on activated T cells and during severe inflammation on NK cells and mast cells. Experimental evidences revealed that genetic deficiency of both these proteins can lead to deleterious effects in an individual. On the other hand, interferon-stimulated genes (ISGs) possess potent antiviral properties and directly or indirectly alter acute neuroinflammation. In this review, we will discuss the role of an ISG, ISG54, and its tetratricopeptide repeat protein Ifit2; the genetic and experimental studies on the role of CD40 and CD40L in a virus-induced neuroinflammatory demyelination model.

The diagnostic/prognostic roles and biological function of the IFIT family members in acute myeloid leukemia.

BACKGROUND: The Interferon-induced protein with tetratricopeptide repeat (IFIT) family, IFIT1/2/3/5, play an important role in different tumors progression. However, the prognosis significance and biological role of IFIT family members in acute myeloid leukemia (AML) remains unclear. METHODS: We obtained the gene expression data and clinical information of 173 AML patients from The Cancer Genome Atlas (TCGA) database. Several databases were used in our study, including GEPIA, MethSurv, STRING, GSCA and GeneMANIA database. RESULTS: The mRNA expression of IFIT1/2/3/5 was elevated in AML patients and had a high ability to distinguish AML from controls based on the receiver operating characteristic (ROC) curve (AUC > 0.9). Kaplan-Meier survival analysis showed that higher levels of IFIT2/3/5 expression predict poor prognosis in AML patients. Besides, the DNA methylation analysis suggested that 7 CpG sites of IFIT2, 4 CpG sites of IFIT3 and 10 CpG sites of IFIT5 were significantly associated with the prognosis of AML patients. In addition, IFIT2/3/5 expression was significantly positively associated with the immune cell infiltration and immune checkpoint expression, such as CTLA4, PDCD1, LAG3, and TIGIT. Finally, drug sensitivity analysis revealed that AML patients with high expression of IFIT2/3/5 were resistant to multiple drugs, but sensitive to dasatinib. CONCLUSION: IFIT family genes might serve as biomarkers for diagnosis, prognosis and drug sensitivity in AML patients. The activation or blocking of IFIT-related signaling pathways may provide novel insights into immunotherapy for patients with AML.