Project description:Bovine leukemia virus (BLV) Tax is a transcriptional activator of viral replication and a key contributor to oncogenic potential. We previously identified interesting mutant forms of Tax with elevated (TaxD247G) or reduced (TaxS240P) transactivation effects on BLV replication and propagation. In this study, to identify genes that play a role in the cascade of signal events regulated by wild-type and mutant Tax proteins, we used a large-scale host cell gene-profiling approach. HeLa cells transiently transfected with the pCAGGS vector for the control sample was compared with HeLa cells transiently transfected with the pCAGGS-Tax-FLAG vector. These cells were incubated for 30h after transfection and total RNA was isolated.
Project description:Bovine leukemia virus (BLV) Tax is a transcriptional activator of viral replication and a key contributor to oncogenic potential. We previously identified interesting mutant forms of Tax with elevated (TaxD247G) or reduced (TaxS240P) transactivation effects on BLV replication and propagation. In this study, to identify genes that play a role in the cascade of signal events regulated by wild-type and mutant Tax proteins, we used a large-scale host cell gene-profiling approach.
Project description:Human T cell leukemia virus type 1 (HTLV-1) Tax is potent activator of viral and cellular gene expression that interacts with a number of cellular proteins. In this study, a large-scale host cell signaling events related to cellular proliferation were used to identify genes involved in Tax-mediated cell signaling events related to cellular proliferation and apoptosis. HeLa cell transiently transfected with with pCAGGS vector for control sample was compared with HeLa cell transiently transfected with with pCAGGS-Tax-FLAG vector. These cells were incubated for 30h after transfection and were used for total RNA isolation.
Project description:Background: Bovine leukemia virus (BLV) microRNAs (miRNAs) contribute to viral latency and immune evasion. Naturally occurring single-nucleotide polymorphisms (SNPs) within the BLV miRNA cluster have been associated with persistent lymphocytosis in cattle, yet their functional impact remains unclear. Aims: This study aims to (1) evaluate how SNPs in BLV miRNAs affect miRNA biogenesis and mature miRNA levels; (2) determine whether specific SNPs alter miRNA–mRNA interactions and identify affected targets; and (3) characterize transcriptomic changes induced by reference versus SNP-bearing miRNAs. Methods: BLV miRNA loci were PCR-amplified and sequenced from 53 blood samples of infected cattle. Both reference and SNP-containing precursors were cloned into expression vectors and co-transfected with an miRNA-deficient BLV clone into HEK293T cells. Mature miRNA levels were quantified via stem-loop RT-qPCR. Computational target prediction (miRanda) validated changes in mRNA targeting. Gene-expression effects were assessed using Agilent microarrays, with selected findings confirmed by RT-qPCR and subjected to pathway enrichment analysis (IPA). Significance: This work will elucidate how BLV miRNA polymorphisms modify miRNA maturation and target recognition, reshape host gene networks, and contribute to viral persistence and immune modulation.
Project description:Bovine Leukemia Virus (BLV)-induced tumoral development is a multifactorial phenomenon which remains incompletely understood. Here, we highlight the critical role of the cellular CCCTC-binding factor (CTCF) both in the regulation of BLV transcriptional activities and in the deregulation of the three-dimensional (3D) chromatin architecture surrounding the BLV integration site. We demonstrated the in vivo recruitment of CTCF to three conserved CTCF binding motifs along the BLV provirus. Next, we showed the localization of CTCF to transitions in the histone modifications profile along BLV genome as well as its implication in the repression the 5’Long Terminal Repeat (LTR) promoter activity, thereby contributing to viral latency, while favoring the 3’LTR promoter activity. Finally, we demonstrated that BLV integration deregulated host cellular 3D chromatin organization through the formation of viral/host chromatin loops. Altogether, our results highlight CTCF as a new critical effector of BLV transcriptional regulation and BLV-induced physiopathology.
Project description:Bovine Leukemia Virus (BLV)-induced tumoral development is a multifactorial phenomenon which remains incompletely understood. Here, we highlight the critical role of the cellular CCCTC-binding factor (CTCF) both in the regulation of BLV transcriptional activities and in the deregulation of the three-dimensional (3D) chromatin architecture surrounding the BLV integration site. We demonstrated the in vivo recruitment of CTCF to three conserved CTCF binding motifs along the BLV provirus. Next, we showed the localization of CTCF to transitions in the histone modifications profile along BLV genome as well as its implication in the repression the 5’Long Terminal Repeat (LTR) promoter activity, thereby contributing to viral latency, while favoring the 3’LTR promoter activity. Finally, we demonstrated that BLV integration deregulated host cellular 3D chromatin organization through the formation of viral/host chromatin loops. Altogether, our results highlight CTCF as a new critical effector of BLV transcriptional regulation and BLV-induced physiopathology.
Project description:Viral tumor models have significantly contributed to our understanding of oncogenic mechanisms. How transforming delta-retroviruses induce malignancy however remains poorly understood, especially as viral mRNA/protein are tightly silenced in tumors. Here, using deep sequencing of broad windows of small RNA sizes in the Bovine Leukemia Virus ovine model of leukemia/lymphoma, we provide evidence of the production of non-canonical Pol III-transcribed viral microRNAs in leukemic B-cells in the complete absence of Pol II 5' LTR-driven transcriptional activity. Processed from a cluster of five independent self-sufficient transcriptional units located in a proviral region dispensable for in vivo infectivity, BLV microRNAs represent ~ 40 % of all microRNAs in both experimental and natural malignancy. They are conserved across tumors and associate with Argonautes, consistent with a critical function in silencing of important cellular and/or viral targets. BLV microRNAs are strongly expressed at pre-leukemic stages and remain at high levels in malignant cells despite the absence of structural and regulatory gene expression, suggesting a key role in tumor onset and progression. Identification of small RNA populations in BLV-induced leukemia
Project description:Bovine leukaemia virus (BLV) is a retrovirus that infects cattle, causing Bovine Enzootic Leukosis, a chronic disease characterized by the proliferation of infected B cells. BLV proviral load (PVL) is a key determinant of disease progression and transmission risk. Cattle can exhibit distinct phenotypes of low PVL (LPVL) or high PVL (HPVL), which remain stable throughout their lifetime. Differential expression analysis performed in edgeR identified 1,908 differentially expressed genes (DEGs) between HPVL and LPVL animals, including 774 downregulated (DReg) and 1134 upregulated (UReg) genes.
2025-03-28 | GSE282244 | GEO
Project description:Effect of bovine leukemia virus (BLV) infection on bovine mammary epithelial cells transcriptome profile.