Induction of interferon-stimulated genes by Simian virus 40 T antigens

AbstractSimian virus 40 (SV40) large T antigen (TAg) is a multifunctional oncoprotein essential for productive viral infection and for cellular transformation. We have used microarray analysis to examine the global changes in cellular gene expression induced by wild-type T antigen (TAgwt) and TAg-mutants in mouse embryo fibroblasts (MEFs). The expression profile of approximately 800 cellular genes was altered by TAgwt and a truncated TAg (TAgN136), including many genes that influence cell cycle, DNA-replication, transcription, chromatin structure and DNA repair. Unexpectedly, we found a significant number of immune response genes upregulated by TAgwt including many interferon-stimulated genes (ISGs) such as ISG56, OAS, Rsad2, Ifi27 and Mx1. Additionally, we also observed activation of STAT1 by TAgwt. Our genetic studies using several TAg-mutants reveal an unexplored function of TAg and indicate that the LXCXE motif and p53 binding are required for the upregulation of ISGs

Raw Sewage Harbors Diverse Viral Populations

At this time, about 3,000 different viruses are recognized, but metagenomic studies suggest that these viruses are a small fraction of the viruses that exist in nature. We have explored viral diversity by deep sequencing nucleic acids obtained from virion populations enriched from raw sewage. We identified 234 known viruses, including 17 that infect humans. Plant, insect, and algal viruses as well as bacteriophages were also present. These viruses represented 26 taxonomic families and included viruses with single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), positive-sense ssRNA [ssRNA(+)], and dsRNA genomes. Novel viruses that could be placed in specific taxa represented 51 different families, making untreated wastewater the most diverse viral metagenome (genetic material recovered directly from environmental samples) examined thus far. However, the vast majority of sequence reads bore little or no sequence relation to known viruses and thus could not be placed into specific taxa. These results show that the vast majority of the viruses on Earth have not yet been characterized. Untreated wastewater provides a rich matrix for identifying novel viruses and for studying virus diversity

Global Genome Demethylation Causes Transcription-Associated DNA Double Strand Breaks in HPV-Associated Head and Neck Cancer Cells

High levels of DNA methylation at CpG loci are associated with transcriptional repression of tumor suppressor genes and dysregulation of DNA repair genes. Human papilloma virus (HPV)-associated head and neck squamous cell carcinomas (HNSCC) have high levels of DNA methylation and methylation has been associated with dampening of an innate immune response in virally infected cells. We have been exploring demethylation as a potential treatment in HPV+ HNSCC and recently reported results of a window clinical trial showing that HNSCCs are particularly sensitive to demethylating agent 5-azacytidine (5-aza). Mechanistically, sensitivity is partially due to downregulation of HPV genes expression and restoration of tumor suppressors p53 and Rb. Here, for the first time, we show that 5-azaC treatment of HPV+ HNSCC induces replication and transcription-associated DNA double strand breaks (DSBs) that occur preferentially at demethylated genomic DNA. Blocking replication or transcription prevented formation of DNA DSBs and reduced sensitivity of HPV-positive head and neck cancer cells to 5-azaC, demonstrating that both replication and active transcription are required for formation of DSBs associated with 5-azaC

The Dynamics of Sensorimotor Cortical Oscillations during the Observation of Hand Movements: An EEG Study

Background The observation of action done by others determines a desynchronization of the rhythms recorded from cortical central regions. Here, we examined whether the observation of different types of hand movements (target directed, non-target directed, cyclic and non-cyclic) elicits different EEG cortical temporal patterns. Methodology Video-clips of four types of hand movements were shown to right-handed healthy participants. Two were target directed (grasping and pointing) motor acts; two were non-target directed (supinating and clenching) movements. Grasping and supinating were performed once, while pointing and clenching twice (cyclic movements). High-density EEG was recorded and analyzed by means of wavelet transform, subdividing the time course in time bins of 200 ms. The observation of all presented movements produced a desynchronization of alpha and beta rhythms in central and parietal regions. The rhythms desynchronized as soon as the hand movement started, the nadir being reached around 700 ms after movement onset. At the end of the movement, a large power rebound occurred for all bands. Target and non-target directed movements produced an alpha band desynchronization in the central electrodes at the same time, but with a stronger desynchronization and a prolonged rebound for target directed motor acts. Most interestingly, there was a clear correlation between the velocity profile of the observed movements and beta band modulation. Significance Our data show that the observation of motor acts determines a modulation of cortical rhythm analogous to that occurring during motor act execution. In particular, the cortical motor system closely follows the velocity of the observed movements. This finding provides strong evidence for the presence in humans of a mechanism (mirror mechanism) mapping action observation on action execution motor programs

Human polyomavirus BKV infection of endothelial cells results in interferon pathway induction and persistence.

Polyomavirus BKV is highly prevalent among humans. The virus establishes an asymptomatic persistent infection in the urinary system in healthy people, but uncontrolled productive infection of the virus in immunocompromised patients can lead to serious diseases. In spite of its high prevalence, our knowledge regarding key aspects of BKV polyomavirus infection remains incomplete. To determine tissue and cell type tropism of the virus, primary human epithelial cells, endothelial cells and fibroblasts isolated from the respiratory and urinary systems were tested. Results from this study demonstrated that all 9 different types of human cells were infectable by BKV polyomavirus but showed differential cellular responses. In microvascular endothelial cells from the lung and the bladder, BKV persistent infection led to prolonged viral protein expression, low yield of infectious progeny and delayed cell death, in contrast with infection in renal proximal tubular epithelial cells, a widely used cell culture model for studying productive infection of this virus. Transcriptomic profiling revealed the activation of interferon signaling and induction of multiple interferon stimulated genes in infected microvascular endothelial cells. Further investigation demonstrated production of IFNβ and secretion of chemokine CXCL10 by infected endothelial cells. Activation of IRF3 and STAT1 in infected endothelial cells was also confirmed. In contrast, renal proximal tubular epithelial cells failed to mount an interferon response and underwent progressive cell death. These results demonstrated that microvascular endothelial cells are able to activate interferon signaling in response to polyomavirus BKV infection. This raises the possibility that endothelial cells might provide initial immune defense against BKV infection. Our results shed light on the persistence of and immunity against infection by BKV polyomavirus

Simian Virus 40 T-Antigen-Mediated Gene Regulation in Enterocytes Is Controlled Primarily by the Rb-E2F Pathway▿

Simian virus 40 large T antigen (TAg) contributes to cell transformation, in part, by targeting two well-characterized tumor suppressors, pRb and p53. TAg expression affects the transcriptional circuits controlled by Rb and by p53. We have performed a microarray analysis to examine the global change in gene expression induced by wild-type TAg (TAgwt) and TAg mutants, in an effort to link changes in gene expression to specific transforming functions. For this analysis we have used enterocytes from the mouse small intestine expressing TAg. Expression of TAgwt in the mouse intestine results in hyperplasia and dysplasia. Our analysis indicates that practically all gene expression regulated by TAg in enterocytes is dependent upon its binding and inactivation of the Rb family proteins. To further dissect the role of the Rb family in the induction of intestinal hyperplasia, we have screened several lines of transgenic mice expressing a truncated TAg (TAgN136), which is able to interfere with the Rb pathway but lacks the functions associated with the carboxy terminus of the protein. This analysis confirmed the pivotal association between the Rb pathway and the induction of intestinal hyperplasia and revealed that upregulation of p53 target genes is not associated with the tumorigenic phenotype. Furthermore, we found that TAgN136 was sufficient to induce intestinal hyperplasia, although the appearance of dysplasia was significantly delayed

Raw sewage harbors diverse viral populations

At this time, about 3,000 different viruses are recognized, but metagenomic studies suggest that these viruses are a small fraction of the viruses that exist in nature. We have explored viral diversity by deep sequencing nucleic acids obtained from virion populations enriched from raw sewage. We identified 234 known viruses, including 17 that infect humans. Plant, insect, and algal viruses as well as bacteriophages were also present. These viruses represented 26 taxonomic families and included viruses with single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), positive-sense ssRNA [ssRNA(¿)], and dsRNA genomes. Novel viruses that could be placed in specific taxa represented 51 different families, making untreated wastewater the most diverse viral metagenome (genetic material recovered directly from environmental samples) examined thus far. However, the vast majority of sequence reads bore little or no sequence relation to known viruses and thus could not be placed into specific taxa. These results show that the vast majority of the viruses on Earth have not yet been characterized. Untreated wastewater provides a rich matrix for identifying novel viruses and for studying virus diversity

Merkel Cell Polyomavirus Exhibits Dominant Control of the Tumor Genome and Transcriptome in Virus-Associated Merkel Cell Carcinoma

ABSTRACT Merkel cell polyomavirus is the primary etiological agent of the aggressive skin cancer Merkel cell carcinoma (MCC). Recent studies have revealed that UV radiation is the primary mechanism for somatic mutagenesis in nonviral forms of MCC. Here, we analyze the whole transcriptomes and genomes of primary MCC tumors. Our study reveals that virus-associated tumors have minimally altered genomes compared to non-virus-associated tumors, which are dominated by UV-mediated mutations. Although virus-associated tumors contain relatively small mutation burdens, they exhibit a distinct mutation signature with observable transcriptionally biased kataegic events. In addition, viral integration sites overlap focal genome amplifications in virus-associated tumors, suggesting a potential mechanism for these events. Collectively, our studies indicate that Merkel cell polyomavirus is capable of hijacking cellular processes and driving tumorigenesis to the same severity as tens of thousands of somatic genome alterations