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Human guanylate binding proteins (GBPs) are key players of interferon–gamma (IFNγ)-induced cell intrinsic defense mechanisms targeting intracellular pathogens. In this study, we combine the well-established Toxoplasmagondii infection model with three in vitro macrophage culture systems to delineate the contribution of individual GBP family members to control this apicomplexan parasite. Use of high-throughput imaging assays and genome engineering allowed us to define a role for GBP1, 2 and 5 in parasite infection control. While GBP1 performs a pathogen-proximal, parasiticidal and growth-restricting function through accumulation at the parasitophorous vacuole of intracellular Toxoplasma, GBP2 and GBP5 perform a pathogen-distal, growth-restricting role. We further find that mutants of the GTPase or isoprenylation site of GBP1/2/5 affect their normal function in Toxoplasma control by leading to mis-localization of the proteins., In human macrophages, guanylate binging protein 1, 2 and 5 (GBP1/2/5) control the growth of the parasite Toxoplasma gondii, with solely GBP1 targeting the parasite vacuole for elimination.

Background: Mainstream application of cancer immunotherapy is hampered by the low response rate of most cancer patients. A novel immunotherapeutic target or a biomarker predicting response to immunotherapy needs to be developed. Guanylate-binding protein 1 (GBP1) is an interferon (IFN)-inducible guanosine triphosphatases (GTPases) involving inflammation and infection. However, the immunological effects of GBP1 in pan-cancer patients are still obscure.Methods: Using large-scale public data, we delineated the landscape of GBP1 across 33 cancer types. The correlation between GBP1 expression or mutation and immune cell infiltration was estimated by ESTIMATE, TIMER, xCell, and quanTIseq algorithms. GBP1-related genes and proteins were subjected to function enrichment analysis. Clustering analysis explored the relationship between GBP1 expression and anti-tumor immune phenotypes. We assessed the patient’s response to immunotherapy using the tumor immune dysfunction and exclusion (TIDE) score and immunophenoscore (IPS). Furthermore, we validated the predictive power of GBP1 expression in four independent immunotherapy cohorts.Results: GBP1 was differentially expressed in tumors and normal tissues in multiple cancer types. Distinct correlations existed between GBP1 expression and prognosis in cancer patients. GBP1 expression and mutation were positively associated with immune cell infiltration. Function enrichment analysis showed that GBP1-related genes were enriched in immune-related pathways. Positive correlations were also observed between GBP1 expression and the expression of immune checkpoints, as well as tumor mutation burden (TMB). Pan-cancer patients with higher GBP1 expression were more inclined to display “hot” anti-tumor immune phenotypes and had lower TIDE scores and higher immunophenoscore, suggesting that these patients had better responses to immunotherapy. Patients with higher GBP1 expression exhibited improved overall survival and clinical benefits in immunotherapy cohorts, including the Gide et al. cohort [area under the curve (AUC): 0.813], the IMvigor210 cohort (AUC: 0.607), the Lauss et al. cohort (AUC: 0.740), and the Kim et al. cohort (AUC: 0.793).Conclusion: This study provides comprehensive insights into the role of GBP1 in a pan-cancer manner. We identify GBP1 expression as a predictive biomarker for immunotherapy, potentially enabling more precise and personalized immunotherapeutic strategies in the future.

The phosphatase of regenerating liver (PRL) family, including PRL-1, PRL-2, and PRL-3, comprises protein tyrosine phosphatases whose deregulation is associated with the tumorigenesis and metastasis of many types of cancer. However, the underlying mechanism is poorly understood. In this study, aiming to increase understanding of the molecular mechanisms underlying the functions of PRL-1 and PRL-3, a yeast two-hybrid system was employed to screen for their interacting proteins. Alignment with the NCBI BLAST database revealed 12 interactive proteins: Synaptic nuclear envelope protein 2, emerin, mannose 6-phosphate receptor-binding protein 1, low-density lipoprotein receptor-related protein 10, Rab acceptor 1, tumor protein D52-like 2, selectin P ligand (SELPLG), guanylate binding protein 1, transmembrane and ubiquitin-like domain-containing 2, NADH:ubiquinone oxidoreductase subunit B8, syndecan 4 and FK506-binding protein 8 (FKBP8). These proteins are associated with cell proliferation, apoptosis, immune response, cell fate specification and metabolic process in biological process categories, and involved in various signaling pathways, including Alzheimer's disease, Parkinson's disease, Huntington's disease, hypertrophic cardiomyopathy and cell adhesion molecules. Interactions of PRL-1 with the prey proteins SELPLG and FKBP8 were confirmed by immunoprecipitation or immunostaining. Furthermore, SELPLG and FKBP8 suppressed PRL-1- or PRL-3-mediated p53 activity. Identification of the proteins interacting with PRL family proteins may provide valuable information to better understand the mechanism of PRL-mediated signal transduction in cancer and other diverse diseases.

Glioblastoma multiforme (GBM) is the most common and deadly primary brain tumor in adults. Epidermal growth factor receptor (EGFR) is frequently amplified and mutated in GBM. We previously reported that Guanylate binding protein-1 (GBP1) is a novel transcriptional target gene of EGFR and plays a role in GBM invasion. Here we demonstrate that GBP1 can also be induced by EGFRvIII at the transcriptional level through the p38 MAPK/Yin Yang 1 (YY1) signaling pathway. Silencing of GBP1 by RNA interference significantly inhibits EGFRvIII-mediated GBM cell proliferation in vitro and in a mouse model. Overexpression of GBP1 has no obvious effect on glioblastoma cell proliferation in vitro. In contrast, in an orthotopic glioma mouse model GBP1 overexpression significantly promotes glioma growth and reduces survival rate of glioma-bearing mice by increasing cell proliferation and decreasing cell apoptosis in tumor. Clinically, GBP1 expression is elevated in human GBM tumors and positively correlates with EGFRvIII status in GBM specimens, and its expression is inversely correlated with the survival rate of GBM patients. Taken together, these results reveal that GBP1 may serve as a potential therapeutic target for GBMs with EGFRvIII mutation.

Interferons (IFNs) are key players in the antiviral response. IFN sensing by the cell activates transcription of IFN-stimulated genes (ISGs) able to induce an antiviral state by affecting viral replication and release. IFN also induces the expression of ISGs that function as negative regulators to limit the strength and duration of IFN response. The ISGs identified so far belong to coding genes. However, only a small proportion of the transcriptome corresponds to coding transcripts and it has been estimated that there could be as many coding as long non-coding RNAs (lncRNAs). To address whether IFN can also regulate the expression of lncRNAs, we analyzed the transcriptome of HuH7 cells treated or not with IFNα2 by expression arrays. Analysis of the arrays showed increased levels of several well-characterized coding genes that respond to IFN both at early or late times. Furthermore, we identified several IFN-stimulated or -downregulated lncRNAs (ISRs and IDRs). Further validation showed that ISR2, 8, and 12 expression mimics that of their neighboring genes GBP1, IRF1, and IL6, respectively, all related to the IFN response. These genes are induced in response to different doses of IFNα2 in different cell lines at early (ISR2 or 8) or later (ISR12) time points. IFNβ also induced the expression of these lncRNAs. ISR2 and 8 were also induced by an influenza virus unable to block the IFN response but not by other wild-type lytic viruses tested. Surprisingly, both ISR2 and 8 were significantly upregulated in cultured cells and livers from patients infected with HCV. Increased levels of ISR2 were also detected in patients chronically infected with HIV. This is relevant as genome-wide guilt-by-association studies predict that ISR2, 8, and 12 may function in viral processes, in the IFN pathway and the antiviral response. Therefore, we propose that these lncRNAs could be induced by IFN to function as positive or negative regulators of the antiviral response.

Background Dengue virus (DENV), the causative agent of human Dengue hemorrhagic fever, is a mosquito-borne virus found in tropical and sub-tropical regions around the world. Vaccines against DENV are currently unavailable. Guanylate-binding protein 1 (GBP1) is one of the Interferon (IFN) stimulated genes (ISGs) and has been shown important for host immune defense against various pathogens. However, the role of GBP1 during DENV infection remains unclarified. In this study, we evaluated the relevance of GBP1 to DENV infection in in vitro model. Findings Quantitative RT-PCR (qRT-PCR) and Western blot showed that the expression of mouse Gbp1 was dramatically upregulated in DENV-infected RAW264.7 cells. The intracellular DENV loads were significantly higher in Gbp1 silenced cells compared with controls. The expression levels of selective anti-viral cytokines were decreased in Gbp1 siRNA treated cells, while the transcription factor activity of NF-κB was impaired upon GBP1 silencing during infection. Conclusions Our data suggested that GBP1 plays an antiviral role during DENV infection.