Dysregulation of histone methylation in SV40 chromosomes during replication results in aberrant transcription and chromatin structure
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PROVIDER: PRJNA1162068 | ENA |
REPOSITORIES: ENA
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Project description:Since early and late transcription are both regulated from the same central regulatory region in SV40 chromatin, the location of nucleosomes carrying histone modifications may contribute to controlling the direction of transcription from the regulatory region. This could occur through the generation of active chromatin in the direction of transcription and repressive chromatin in the opposite direction. In order to test this hypothesis, we have characterized the products of SV40 transcription and location of nucleosomes carrying histone modifications in SV40 chromatin following treatment of infected cells with inhibitors of histone methylation metabolism. The inhibitors used included GSK-LSD1 to inhibit demethylation of H3K4me1 and H3K9me1, A366 to inhibit the introduction of H3K9me1, and UNC1999 to inhibit the introduction of H3K27me3. The results are consistent with a regulatory model in which nucleosomes carrying H3K9me1 and H3K27me3 located at the ends of the SV40 regulatory region act to regulate transcription.
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Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis.
2012-10-31 | GSE31097 | GEO
Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis.
2012-10-31 | GSE29117 | GEO
Project description:This SuperSeries is composed of the following subset Series: GSE29117: Mammary carcinomas in WAP-SV40 transgenic mice [gene expression] GSE31097: Mammary carcinomas in WAP-SV40 transgenic mice [aCGH] GSE33038: Involuted normal mammary gland in WAP-SV40 transgenic mice [gene expression] Refer to individual Series
2012-10-31 | E-GEOD-31212 | biostudies-arrayexpress
Project description:ATRX loss in glioma results in epigenetic dysregulation of cell cycle phase transition
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Project description:Transgenic expression in mice of two synergistically acting SV40 early region encoded proteins, large (LT) and small (sT) tumor antigens, in the mammary epithelium recapitulates loss of p53 and Rb function and deregulation of PP2A-controlled mitogenic pathways in human breast cancer. In primiparous mice, WAP-promoter driven expression of SV40 proteins induces well and poorly differentiated mammary adenocarcinomas. We performed a correlative aCGH and gene expression analysis of 25 monofocal tumors, representing four histopathological grades, to explore the molecular traits of SV40-induced mammary tumors and to emphasize the relevance of this tumor model for human breast tumorigenesis.
2012-10-31 | GSE33038 | GEO
Project description:SV40 transforms cells through the action of two oncoproteins, large T antigen and small t antigen. Small t antigen targets phosphatase PP2A, while large T antigen stimulates cell proliferation and survival by action on multiple proteins, including the tumor suppressors Rb and p53. Large T antigen also binds components of the transcription initiation complex and several transcription factors. We examine global gene expression in SV40-transformed REF52 cells. SV40 transformation alters the expression of approximately 480 cellular genes. Much of this regulation is consistent with T antigen action on the Rb-E2F pathway.
2009-09-01 | GSE7836 | GEO
Project description:Polyomaviruses are a family of small DNA tumor viruses that includes several pathogenic human members, including Merkel cell polyomavirus, BK virus and JC virus. As is characteristic of DNA tumor viruses, gene expression in polyomaviruses is temporally regulated into an early phase, consisting of the viral regulatory proteins, and a late phase, consisting of the viral structural proteins. Previously, the late transcripts expressed by the prototypic polyomavirus simian virus 40 (SV40) were reported to contain several adenosines bearing methyl groups at the N6 position (m6A), although the precise location of these m6A residues, and their phenotypic effects, have not been investigated. Here, we first demonstrate that overexpression of the key m6A reader protein YTHDF2 induces more rapid viral replication, and larger viral plaques, in SV40 infected BSC40 cells, while mutational inactivation of the endogenous YTHDF2 gene, or the m6A methyltransferase METTL3, has the opposite effect, thus suggesting a positive role for m6A in the regulation of SV40 gene expression. To directly test this hypothesis, we mapped sites of m6A addition on SV40 transcripts and identified two m6A sites on the viral early transcripts and eleven m6A sites on the late mRNAs. Using synonymous mutations, we inactivated the majority of the m6A sites on the SV40 late mRNAs and observed that the resultant viral mutant replicated more slowly than wild type SV40. Alternative splicing of SV40 late mRNAs was unaffected by the reduction in m6A residues and our data instead suggest that m6A enhances the translation of viral late transcripts. Together, these data argue that the addition of m6A residues to the late transcripts encoded by SV40 plays an important role in enhancing viral gene expression and, hence, replication.
2018-02-08 | GSE106698 | GEO
Project description:Metaphase karyotyping is an established diagnostic standard in acute myeloid leukemia (AML) for risk stratification. One of the cytogenetic findings in AML are structurally highly abnormal marker chromosomes. In this study, we have assessed frequency, cytogenetic characteristics, prognostic impact and underlying biological origin of marker chromosomes. Given their inherent gross structural chromosomal damage, we speculated that they may arise from chromothripsis, a recently described phenomenon of chromosome fragmentation in a single catastrophic event. In 2 large consecutive prospective, randomized, multicenter, intensive chemotherapy trials (AML96, AML2003) from the Study Alliance Leukemia (SAL), marker chromosomes were detectable in 165/1026 (16.1%) of aberrant non-core-binding-factor (CBF) karyotype patients. Adverse-risk karyotypes displayed a higher frequency of marker chromosomes (26.5% in adverse-risk, 40.3% in complex aberrant and 41.2% in abnormality(17p) karyotypes, p<.0001 each). Marker chromosomes were associated with a poorer prognosis compared to other non-CBF aberrant karyotypes and led to lower remission rates (CR+CRi), inferior event-free survival as well as overall survival in both trials. In multivariate analysis, marker chromosomes independently predicted poor prognosis in the AML96 trial ≤60 years. As detected by array-CGH, about one third of marker chromosomes (18/49) had arisen from chromothripsis, whereas this phenomenon was virtually undetectable in a control group of marker chromosome-negative complex aberrant karyotypes (1/34). The chromothripsis-positive cases were characterized by a particularly high degree of karyotype complexity and dismal prognosis. In conclusion, marker chromosomes are indicative of chromothripsis and associated with poor prognosis per se and not merely by association with other adverse cytogenetic features.
2017-03-29 | GSE93886 | GEO