Gene expression profiles of control GC424 tumor cell lines and after downregulation of the SV40 large T-antigen
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE27710 | GEO | 2012/08/02
SECONDARY ACCESSION(S): PRJNA141869
REPOSITORIES: GEO
Similar Datasets
Project description:Analysis of global gene expression in a tumor cell line established from a CEA424-Tag mouse and comparison with the expressed gene profile after downregulating the expression of the large T antigen Total RNA obtained from cultured control cell lines and after siRNA mediated downregulation of the SV40 large T antigen
2012-08-01 | E-GEOD-27710 | biostudies-arrayexpress
Project description:SV40 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 and TAg-mutants, in an effort to link changes in gene expression to specific transforming functions. For this analysis we have used MEFs expressing TAg or infected by SV40. Our analysis indicates that TAg can induce interferon-stimulated genes in MEFs and that this induction depends upon the LXCXE motif and p53 binding.
2010-08-31 | GSE20620 | GEO
Project description:SV40 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 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 TAg 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.
2009-09-01 | GSE16389 | GEO
Project description:BACKGROUND: A large fraction of murine tumors induced by transgenic expression of SV40 large T antigen (SV40 TAg) exhibits a neuroendocrine phenotype. It is unclear whether SV40 TAg induces the neuroendocrine phenotype by preferential transformation of progenitor cells committed to the neuroendocrine lineage or by transcriptional activation of neuroendocrine genes. METHODOLOGY/PRINCIPAL FINDINGS: To address this question we analyzed CEA424-SV40 TAg-transgenic mice that develop spontaneous tumors in the antral stomach region. Immunohistology revealed expression of the neuroendocrine marker chromogranin A in tumor cells. By ELISA an 18-fold higher level of serotonin could be detected in the blood of tumor-bearing mice in comparison to nontransgenic littermates. Transcriptome analyses of antral tumors combined with gene set enrichment analysis showed significant enrichment of genes considered relevant for human neuroendocrine tumor biology. This neuroendocrine gene signature was also expressed in 424GC, a cell line derived from a CEA424-SV40 TAg tumor, indicating that the tumor cells exhibit a similar neuroendocrine phenotype also in vitro. Treatment of 424GC cells with SV40 TAg-specific siRNA downregulated expression of the neuroendocrine gene signature. CONCLUSIONS/SIGNIFICANCE: SV40 TAg thus appears to directly induce a neuroendocrine gene signature in gastric carcinomas of CEA424-SV40 TAg-transgenic mice. This might explain the high incidence of neuroendocrine tumors in other murine SV40 TAg tumor models. Since the oncogenic effect of SV40 TAg is caused by inactivation of the tumor suppressor proteins p53 and RB1 and loss of function of these proteins is commonly observed in human neuroendocrine tumors, a similar mechanism might cause neuroendocrine phenotypes in human tumors.
| S-EPMC3258231 | biostudies-literature
Project description:SV40 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 and TAg-mutants, in an effort to link changes in gene expression to specific transforming functions. For this analysis we have used MEFs expressing TAg or infected by SV40. Our analysis indicates that TAg can induce interferon-stimulated genes in MEFs and that this induction depends upon the LXCXE motif and p53 binding. Two independent wild-type MEFs and three independent MEF cell lines expressing TAg and the mutants were used. Additionally, three independent mock and SV40 infections were conduted in MEFs. Total RNA was isolated from with the RNeasy kit. Total RNA was processed by the Genomics and Proteomics Core Laboratories at the University of Pittsburgh and hybridized to the Affymetrix GeneChip Mouse Genome 430 2.0 array. MAS 5.0 was used to obtain the present/absent calls and CEL files were normalized by RMA to obtain log2 expression values.
2010-08-31 | E-GEOD-20620 | biostudies-arrayexpress
Project description:Simian virus 40 large tumor antigen (LTag) is an efficient helicase motor that unwinds and translocates DNA. The DNA unwinding and translocation of LTag is powered by ATP binding and hydrolysis at the nucleotide pocket between two adjacent subunits of an LTag hexamer. Based on the set of high-resolution hexameric structures of LTag helicase in different nucleotide binding states, we simulated a conformational transition pathway of the ATP binding process using the targeted molecular dynamics method and calculated the corresponding energy profile using the linear response approximation (LRA) version of the semi-macroscopic Protein Dipoles Langevin Dipoles method (PDLD/S). The simulation results suggest a three-step process for the ATP binding from the initial interaction to the final tight binding at the nucleotide pocket, in which ATP is eventually "locked" by three pairs of charge-charge interactions across the pocket. Such a "cross-locking" ATP binding process is similar to the binding zipper model reported for the F1-ATPase hexameric motor. The simulation also shows a transition mechanism of Mg2+ coordination to form the Mg-ATP complex during ATP binding, which is accompanied by the large conformational changes of LTag. This simulation study of the ATP binding process to an LTag and the accompanying conformational changes in the context of a hexamer leads to a refined cooperative iris model that has been proposed previously.
| S-EPMC2739275 | biostudies-literature
Project description:Inactivation of the retinoblastoma (Rb) tumor suppressor by Simian virus 40 (SV40) large T antigen is one of the central features of tumorigenesis induced by SV40. Both the N-terminal J domain and the LxCxE motif of large T antigen are required for inactivation of Rb. The crystal structure of the N-terminal region (residues 7-117) of SV40 large T antigen bound to the pocket domain of Rb reveals that large T antigen contains a four-helix bundle, and residues from helices alpha2 and alpha4 and from a loop containing the LxCxE motif participate in the interactions with Rb. The two central helices and a connecting loop in large T antigen have structural similarities with the J domains of the molecular chaperones DnaJ and HDJ-1, suggesting that large T antigen may use a chaperone mechanism for its biological function. However, there are significant differences between large T antigen and the molecular chaperones in other regions and these differences are likely to provide the specificity needed for large T antigen to inactivate Rb.
| S-EPMC140208 | biostudies-literature
Project description:The small genome of polyomaviruses encodes a limited number of proteins that are highly dependent on interactions with host cell proteins for efficient viral replication. The SV40 large T antigen (LT) contains several discrete functional domains that contribute to the viral life cycle, including the DNA binding and helicase domains. In addition, the LT the C-terminal region is required for lytic infection in certain restrictive cell types. To understand how LT affects the host cell to facilitate viral replication, we expressed full-length or functional domains of LT in cells and identified interacting cellular proteins and performed expression profiling. LT perturbed the expression of p53 target genes and subsets of cell-cycle dependent genes regulated by the DREAM and the B-Myb-MuvB complexes.
2012-10-26 | GSE40567 | GEO
Project description:The small genome of polyomaviruses encodes a limited number of proteins that are highly dependent on interactions with host cell proteins for efficient viral replication. The SV40 large T antigen (LT) contains several discrete functional domains that contribute to the viral life cycle, including the DNA binding and helicase domains. In addition, the LT the C-terminal region is required for lytic infection in certain restrictive cell types. To understand how LT affects the host cell to facilitate viral replication, we expressed full-length or functional domains of LT in cells and identified interacting cellular proteins and performed expression profiling. LT perturbed the expression of p53 target genes and subsets of cell-cycle dependent genes regulated by the DREAM and the B-Myb-MuvB complexes. To examine transcriptome perturbations directly in human cells, we generated expression constructs of each LT fragment. Full length and truncated LT containing N-terminal HA and FLAG epitope tags were expressed from the pMSCV retroviral vector and introduced into U-2 OS cells. Total RNA was isolated from three biological replicate U-2 OS stable cell lines and gene expression was assayed on Affymetrix Human Gene U133 Plus 2.0 arrays.
2012-10-26 | E-GEOD-40567 | biostudies-arrayexpress
Project description:The DNA tumor virus Simian virus 40 (SV40) is a model system for studying eukaryotic replication. SV40 large tumor antigen (LTag) is the initiator/helicase that is essential for genome replication. LTag recognizes and assembles at the viral replication origin. We determined the structure of two multidomain LTag subunits bound to origin DNA. The structure reveals that the origin binding domains (OBDs) and Zn and AAA+ domains are involved in origin recognition and assembly. Notably, the OBDs recognize the origin in an unexpected manner. The histidine residues of the AAA+ domains insert into a narrow minor groove region with enhanced negative electrostatic potential. Computational analysis indicates that this region is intrinsically narrow, demonstrating the role of DNA shape readout in origin recognition. Our results provide important insights into the assembly of the LTag initiator/helicase at the replication origin and suggest that histidine contacts with the minor groove serve as a mechanism of DNA shape readout.
| S-EPMC3748285 | biostudies-literature