Project description:Aberrant activity of type II topoisomerases (TOP2) often causes blocked double-strand breaks (DSBs), whose inefficient repair can seriously compromise genomic stability. One of the two TOP2 paralogs encoded in vertebrates is TOP2B, which has been linked to essential processes such as transcription or genome organization. Few TOP2B genome-wide maps have been profiled, and a comprehensive study of the mechanisms involved in TOP2B-DNA binding is still lacking. Here, we conduct an in silico approach for the prediction of TOP2B binding sites using publicly available sequencing data. We achieve highly accurate predictions and find that open chromatin and architectural factors are the most informative features. We also validate our predictions on experimental data and generate predicted TOP2B tracks that mirror experimental ones with high precision.
Project description:DNA topoisomerase II-β (TOP2B) is fundamental to remove topological problems linked to DNA metabolism and 3D chromatin architecture, but its cut-and-reseal catalytic mechanism can accidentally cause DNA double-strand breaks (DSBs) that can seriously compromise genome integrity. Understanding the factors that determine the genome-wide distribution of TOP2B is therefore not only essential for a complete knowledge of genome dynamics and organization, but also for the implications of TOP2-induced DSBs in the origin of oncogenic translocations and other types of chromosomal rearrangements. Here, we conduct a machine-learning approach for the prediction of TOP2B binding using publicly available sequencing data. We achieve highly accurate predictions, with accessible chromatin and architectural factors being the most informative features. Strikingly, TOP2B is sufficiently explained by only three features: DNase I hypersensitivity, CTCF and cohesin binding, for which genome-wide data are widely available. Based on this, we develop a predictive model for TOP2B genome-wide binding that can be used across cell lines and species, and generate virtual probability tracks that accurately mirror experimental ChIP-seq data. Our results deepen our knowledge on how the accessibility and 3D organization of chromatin determine TOP2B function, and constitute a proof of principle regarding the in silico prediction of sequence-independent chromatin-binding factors.
Project description:Site-specific glycosylation analysis by nLC-MS/MS of recombinant human Fcγ receptors IIA (H&R167 isoforms), IIB and murine Fcγ receptor IIB.
Project description:RNA-Seq of human endothelial cells treated with ACF revealed massive changes on gene expression. These were non-randomly and strongly conserved to murine lung endothelial cells potentially due to DNA topoisomerase inhibition rather than HIF inhibition. Surprisingly, in contrast to protein-coding genes, RNA-Seq yielded that an exceeding number of lncRNAs is upregulated, e.g. FENDRR, H19, HIF1α-AS1 and FLJ31356, whereas BOLA3-AS1 and MEG3 were strongly downregulated. ATAC-Seq demonstrated that ACF leads to strong changes on chromatin accessibility on lncRNA promoters.
Project description:RNA-Seq of human endothelial cells treated with ACF revealed massive changes on gene expression. These were non-randomly and strongly conserved to murine lung endothelial cells potentially due to DNA topoisomerase inhibition rather than HIF inhibition. Surprisingly, in contrast to protein-coding genes, RNA-Seq yielded that an exceeding number of lncRNAs is upregulated, e.g. FENDRR, H19, HIF1α-AS1 and FLJ31356, whereas BOLA3-AS1 and MEG3 were strongly downregulated. ATAC-Seq demonstrated that ACF leads to strong changes on chromatin accessibility on lncRNA promoters.
Project description:Deciphering the molecular pathogenesis of virally induced cancers is challenging due, in part, to the heterogeneity of both viral and host gene expression. Epstein-Barr Virus (EBV) is a ubiquitous herpesvirus prevalent in B-cell lymphomas of the immune suppressed. EBV infection of primary human B cells leads to their immortalization into lymphoblastoid cell lines (LCLs) serving as a model of these lymphomas. In previous studies, our lab has described a temporal model for immortalization with an initial phase characterized by expression of the Epstein-Barr Nuclear Antigens (EBNAs), high c-Myc activity, and hyper-proliferation in the absence of the Latent Membrane Proteins (LMPs), called latency IIb. This is followed by the long-term outgrowth of LCLs expressing the EBNAs along with the LMPs, particularly the NFkB-activating LMP1, defining latency III. LCLs, however, express a broad distribution of LMP1 such that a subset of these cells expresses LMP1 at levels seen in latency IIb, making it difficult to distinguish these two latency states. In this study, we performed mRNA-Seq on early EBV-infected latency IIb cells and latency III LCLs sorted by NFkB activity. We found that latency IIb transcriptomes clustered independently from latency III independent of NFkB. We identified and validated mRNAs defining these latency states. Indeed, we were able to distinguish latency IIb cells from LCLs expressing low levels of LMP1 using multiplex RNA-FISH targeting EBV EBNA2, LMP1, and human CCR7 or MGST1. This study defines latency IIb as a bona fide latency state independent from latency III and identifies biomarkers for understanding EBV-associated tumor heterogeneity