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Mx proteins are key factors of the innate intracellular defense mechanisms that act against viruses induced by type I/III interferons. The family Peribunyaviridae includes many viruses of veterinary importance, either because infection results in clinical disease or because animals serve as reservoirs for arthropod vectors. According to the evolutionary arms race hypothesis, evolutionary pressures should have led to the selection of the most appropriate Mx1 antiviral isoforms to resist these infections. Although human, mouse, bat, rat, and cotton rat Mx isoforms have been shown to inhibit different members of the Peribunyaviridae, the possible antiviral function of the Mx isoforms from domestic animals against bunyaviral infections has, to our knowledge, never been studied. Herein, we investigated the anti-Schmallenberg virus activity of bovine, canine, equine, and porcine Mx1 proteins. We concluded that Mx1 has a strong, dose-dependent anti-Schmallenberg activity in these four mammalian species.

Phase-separated membraneless biomolecular condensates in the cytoplasm and nucleus are now recognized to play a major role in modulating diverse functions in mammalian cells, and contribute to cancer pathogenesis through dysregulated function of condensates of transcription factors such as STAT3 and fusion oncoproteins. Oral cancer, the sixth most prevalent malignancy worldwide, in the absence of overt causes such as tobacco or alcohol, most frequently occurs in a U-shaped zone (floor of mouth, side of tongue, anterior fauces and retromolar region) reflecting the path of liquid transit through the mouth. The cellular basis for this “high-risk” zone and the biochemical mechanisms used by oral cells to combat repetitive tonicity and temperature stresses are incompletely understood. We had previously observed that at 37 °C, in OECM1 oral carcinoma cells, cytoplasmic condensates of antiviral human GFP-MxA GTPase disassembled within 1–2 min of exposure of cells to saliva-like one-third hypotonicity, and underwent “spontaneous” reassembly in the next 5–7 min. Moreover, hypotonic beverages (water, tea, coffee), investigated at 37 °C, triggered this condensate cycling. In the present studies we investigated whether this process was temperature sensitive, representative of cold vs. warm drinks. We observed a slowing of this cycle at 5 °C, and speeding up at 50 °C. The involvement in this disassembly/reassembly process of WNK-SPAK/OSR1 serine-threonine kinase pathway, best studied for regulation of water and Na, K and Cl influx and efflux in kidney tubule cells, was evaluated by us in oral cells using pathway inhibitors WNK463, WNK-IN-11 and closantel. The pan-WNK inhibitor WNK463 inhibited hypotonicity-driven condensate disassembly, while the SPAK/OSR1 inhibitor closantel markedly slowed reassembly. Unexpectedly, the WNK1-selective inhibitor (WNK-IN-11), triggered a dramatic and rapid (within 1 h) spheroid to fibril transition of GFP-MxA condensates in live cells, but without affecting MxA antiviral function. The new data suggest a novel hypothesis for the anatomic localization of oral cancer in the U-shaped “high-risk” zone in the mouth: dysfunction of biomolecular condensates in oral cells along the beverage transit pathway through the mouth due to repetitive tonicity and temperature stresses that might underlie a prooncogenic progression.

Biomolecular condensates in the cytoplasm and nucleus contribute to carcinogenesis through aberrant signaling by assorted transcription factors and fusion oncoproteins. Oral cancer, which is highly prevalent worldwide, frequently occurs in a U-shaped “high-risk” zone (floor of mouth, side of tongue, and anterior fauces) which forms the path of liquid transit through the mouth. We previously reported that environmental stresses of saliva-like hypotonicity and beverage-like temperature changes triggered cycles of disassembly/reassembly of biomolecular condensates of GFP-tagged human myxovirus resistance protein (MxA; alias Mx1) in oral cancer cells. In the present study, we identified some of the constituents of GFP-MxA cytoplasmic condensates in oral cells. These condensates were isolated from interferon (IFN)-λ1-treated GFP-MxA expressing OECM1 human oral cancer cells using magnetic bead-based immunoisolation. Unbiased peptide identification confirmed the presence of MxA/Mx1 peptides; however, the strongest intensity was for the BACH1 transcription factor family. Immunofluorescence analyses confirmed the association of BACH1 and the family member Nrf2 with cytoplasmic human GFP-MxA condensates. Moreover, GFP-BACH1 and GFP-Nrf2 colocalized with cytoplasmic human HA-MxA condensates in transiently transfected OECM1 cells. Western blot assays confirmed the presence of BACH1 and Nrf2 proteins in complexes isolated using anti-MxA pAb. As much as BACH1 and Nrf2 regulate oxidative stress response genes, it was remarkable that immunofluorescence assays revealed the presence of heme oxygenase 1 (HO1)—a downstream redox regulator—in GFP-MxA condensates. However, these condensates were devoid of p62, KEAP1 and Cul3. In terms of aberrant function, in live cells, the Nrf2 transcription factor underwent rapid disassembly and reassembly cycles driven by saliva-like hypotonicity, and was also disassembled by sulforaphane. The data highlight the unexpected intersections in oral cells between MxA condensates and BACH1, Nrf2 and HO1—proteins well known to be involved in pathways regulating cellular responses to environmental and oxidative stresses, antiviral defense, oral epithelial dysplasia, and cancer progression and metastases.

We investigated SARS-CoV-2 potential tropism by surveying expression of viral entry-associated genes in single-cell RNA-sequencing data from multiple tissues from healthy human donors. We co-detected these transcripts in specific respiratory, corneal and intestinal epithelial cells, potentially explaining the high efficiency of SARS-CoV-2 transmission. These genes are co-expressed in nasal epithelial cells with genes involved in innate immunity, highlighting the cells’ potential role in initial viral infection, spread and clearance. The study offers a useful resource for further lines of inquiry with valuable clinical samples from COVID-19 patients and we provide our data in a comprehensive, open and user-friendly fashion at www.covid19cellatlas.org . An analysis of single-cell transcriptomics datasets from different tissues shows that ACE2 and TMPRSS2 are co-expressed in respiratory, corneal and intestinal epithelial cell populations, and that respiratory expression of ACE2 is associated with genes involved in innate immunity.

Background Breast cancer (BC) is a disease with variable morphology, clinical behaviour and response to therapy. Identifying factors associated with the progression of early-stage BC can help understand the risk of metastasis and guide treatment decisions. Myxovirus resistance 1 (MX1), which is involved in the cellular antiviral mechanism, plays a role in some solid tumours; however, its role in invasive BC remains unknown. In this study, we aimed to explore the clinicopathological and prognostic significance of MX1 in BC. Methods MX1 was assessed at the protein level using tissue microarrays from a large well-annotated BC cohort ( n  = 845). The expression of MX1 mRNA was assessed at the transcriptomic level using the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC; n  = 1980) and validated using three publicly available cohorts on Breast Cancer Gene-Expression Miner (bc-GenExMiner version 4.4). The associations between MX1 expression and clinicopathological factors, and outcome were evaluated. Results High MX1 protein expression was associated with features of aggressiveness, including large tumour size, high tumour grade, high Nottingham prognostic index scores, hormone receptor negativity and high Ki67 expression. High MX1 expression showed an association with poor patient outcome and it was an independent predictor of short BC-specific survival ( p  = 0.028; HR = 1.5; 95% CI = 1.0–2.2). Consistent with the protein results, high MX1 mRNA levels showed an association with features of aggressive behaviour and with shorter survival. Conclusion This study identified MX1 as an independent predictor of poor outcome in patients with BC. Further functional studies are needed to investigate the biological role of MX1 in BC and its potential value as a therapeutic target.

Small fiber neuropathy (SFN) affects small-diameter sensory and autonomic nerve fibers, leading to chronic pain and autonomic dysfunction. While SFN can be associated with diabetes and autoimmune diseases, a significant proportion of cases are idiopathic. Although immune-mediated mechanisms are being recognized increasingly in SFN, their precise role remains unclear. This study investigates the presence of autoantibodies against interferon-induced GTP-binding protein MX (MX1) in SFN patients and explores their potential pathogenic role. A total of 59 patients with skin biopsy-confirmed SFN and 20 healthy controls were recruited. Serum samples were analyzed for the presence of anti-MX1 autoantibodies using enzyme-linked immunosorbent assay (ELISA). Immunohistochemistry was performed on rat sciatic nerves to assess the localization of patient IgG to unmyelinated nerve fibers, and immunocytochemistry and flow cytometry confirmed specific binding to MX1. Functional characterization of MX1 was conducted using whole-cell patch-clamp recordings in dorsal root ganglion (DRG) neurons overexpressing MX1. Additionally, protein interactions between MX1 and transient receptor potential cation channel subfamily C member 6 (TRPC6) were assessed using co-immunoprecipitation and surface biotinylation assays. Anti-MX1 autoantibody levels were significantly elevated in SFN patients compared to controls ( p  = 0.0278), particularly in the autoimmune SFN subgroup. Patient sera exhibited IgG binding to unmyelinated nerve fibers, with idiopathic and autoimmune SFN cases showing similar staining patterns, suggesting a similar immune-mediated mechanism. Immunocytochemistry showed binding to HEK293-MX1 cells and flow cytometry revealed higher MX1/WT fluorescence intensity ratios in patient sera, further confirming specific immune recognition of MX1. Patch-clamp recordings demonstrated that MX1 overexpression in DRG neurons led to significant membrane depolarization and increased action potential firing frequency ( p  < 0.0001), indicating heightened neuronal excitability. However, MX1 did not directly interact with TRPC6 or alter its function, suggesting an alternative pathway for its effects. The addition of anti-MX1 IgG did not further modify DRG electrophysiology, implying that the autoimmune component may contribute to SFN pathogenesis through indirect mechanisms. Our findings support the hypothesis that MX1 influences neuronal excitability and plays a role in SFN pathophysiology. Future studies should validate these findings in larger cohorts and explore potential therapeutic strategies targeting MX1-associated pathways in SFN.

The H9N2 avian influenza virus, although not highly pathogenic, still poses ongoing risks to poultry health and food security due to its ability to resist vaccines and its potential to spread to humans. This study investigated the effects of baicalin, a flavonoid derived from , on respiratory mucosal immunity during H9N2 infection. In vitro experiments were conducted using MLE-12 alveolar epithelial cells, and in vivo evaluations were performed in a mouse model of H9N2 infection. Baicalin treatment enhanced the expression of antiviral proteins Mx1 and PKR in a dose- and time-dependent manner, helping to counteract the virus's suppression of these defense proteins. In addition to strengthening this epithelial barrier, baicalin has both antiviral and immune-regulating effects: it directly blocks viral replication and helps restore the CD4+/CD8+ T cell ratio in H9N2-infected mice. Most importantly, baicalin reduces lung damage and spleen shrinkage while keeping the immune system balanced. These results show that baicalin enhances mucosal antiviral defenses by simultaneously regulating innate antiviral pathways (Mx1 and PKR) and restoring adaptive immune balance (CD4+/CD8+ T-cell ratio). These dual protective effects highlight baicalin's potential as a natural therapeutic strategy for improving mucosal immunity against vaccine-resistant influenza viruses such as H9N2, contributing valuable insights into plant-derived immunomodulatory approaches against emerging zoonotic viral threats.

Background Growing evidence has suggested that Type I Interferon (I-IFN) plays a potential role in the pathogenesis of Down Syndrome (DS). This work investigates the underlying function of MX1, an effector gene of I-IFN, in DS-associated transcriptional regulation and phenotypic modulation. Methods We performed assay for transposase-accessible chromatin with high-throughout sequencing (ATAC-seq) to explore the difference of chromatin accessibility between DS derived amniocytes (DSACs) and controls. We then combined the annotated differentially expressed genes (DEGs) and enriched transcriptional factors (TFs) targeting the promoter region from ATAC-seq results with the DEGs in RNA-seq, to identify key genes and pathways involved in alterations of biological processes and pathways in DS. Results Binding motif analysis showed a significant increase in chromatin accessibility of genes related to neural cell function, among others, in DSACs, which is primarily regulated by members of the activator protein-1 (AP-1) transcriptional factor family. Further studies indicated that MX Dynamin Like GTPase 1 (MX1), defined as one of the key effector genes of I-IFN, is a critical upstream regulator. Its overexpression induced expression of AP-1 TFs and mediated inflammatory response, thus leading to decreased cellular viability of DS cells. Moreover, treatment with specific AP-1 inhibitor T-5224 improved DS-associated phenotypes in DSACs. Conclusions This study demonstrates that MX1-mediated AP-1 activation is partially responsible for cellular dysfunction of DS. T-5224 effectively ameliorated DS-associated phenotypes in DSACs, suggesting it as a potential treatment option for DS patients.

Background Systemic lupus erythematosus (SLE) is an incurable autoimmune disease that affects body tissues, but it can be managed with medication. Although therapeutic strategies for SLE have advanced, the underlying molecular mechanisms driving disease pathogenesis remain incompletely understood. Methods This study analyzed gene expression data from three GEO microarray datasets to explore immunity-related differentially expressed genes (DEGs) in SLE. Using WGCNA, we identified gene modules and integrated them with immune-related DEGs to find candidate hub genes, which were validated using RT-qPCR. We constructed a PPI network and performed gene enrichment analysis to identify nine hub genes through ROC curve analysis. We confirmed the link between these hub genes and immune cells, conducted GSEA, and predicted drugs, miRNAs, and transcription factors (TFs) targeting these genes. LASSO and ROC analyses validated a model using immunity-related DEGs. Results The forty immune-related DEGs were identified from a total of 1590 DEGs, 452 WGCN module genes, and 1791 immune genes. Nine hub genes ( MX1 , OAS1 , OASL , IRF7 , RSAD2 , EIF2AK2 , ISG15 , IFIH1 , and STAT1 ) were highlighted using Cytoscape and ROC analysis, with an AUC greater than 0.7. RT-qPCR confirmed significant overexpression of all hub genes except STAT1 in SLE. ssGSEA and GSEA linked these genes to immune cell infiltration and pathways, including \"cell cycle\" and \"RIG-I-like receptor signaling.\" A diagnostic model with three immune-related hub genes ( MX1 , IRF7 , and EIF2AK2 ) demonstrated high accuracy (AUC > 0.8) in distinguishing SLE from healthy controls. Additionally, 9 target drugs, 14 target miRNAs, and 23 TFs were identified for these hub genes. Conclusions MX1, IRF7, and EIF2AK2 may serve as candidate biomarkers for SLE and warrant further investigation.

Background Immune tolerance breakdown at the maternal-fetal interface is implicated in unexplained recurrent pregnancy loss (URPL), but the interplay between T cell hyperactivation and dendritic cells (DCs)-mediated signaling remains poorly defined. Methods First-trimester decidual tissues from 5 healthy controls and 6 URPL patients underwent single-cell RNA sequencing (scRNA-seq, 10× Genomics). Computational analyses included clustering (Seurat), trajectory inference (scTour), intercellular communication (CellChat) and metabolic pathway enrichment (Gene Ontology and scMetabolism). Flow cytometry was performed from 11 patients and 11 healthy controls. Spatial validation was performed via multiplex immunohistochemistry and immunohistochemistry on 12 additional controls and 12 URPL cases. Statistical significance was assessed using Student’s t-test. Results URPL decidua exhibited marked CD3+ T cells and MX1+effector T (Tem) cells infiltration and activation. Flow cytometry analysis confirmed a significant decidua-specific upregulation of T cell activation markers CD25 and CD69 specifically on the MX1+Tem subset in URPL patients compared to controls. MX1+Tem cell subset demonstrated interferon hyperactivation, proliferative hyperactivity and lipid-biased immunometabolism. Pseudotemporal analysis positioned MX1+ Tem cells between classical Tem and exhausted T cell states, suggesting progressive differentiation. CellChat identified DCs as key regulators of MX1+ Tem expansion via aberrant ICOSL signaling, validated by spatial co-localization of ICOSL+ DCs and MX1+ Tem cells in URPL tissues. Conclusion Our findings demonstrate that the aberrant activation and proliferation of MX1+Tem cells as a key immunological feature associated with URPL patients.