Project description:Epstein-Barr virus (EBV) infection converts resting human B cells into permanently growing lymphoblastoid cell lines (LCLs). The viral Epstein-Barr virus nuclear antigen 2 (EBNA2) plays key role in this process. It preferentially binds to B cell enhancers and establishes a specific viral and cellular gene expression program in LCLs. The cellular DNA binding factor CBF1/CSL serves as a sequence specific chromatin anchor for EBNA2. The ubiquitous expression of this highly conserved protein raises the question whether additional cellular factors might determine EBNA2 chromatin binding selectively in B cells. Here we used CBF1 deficient B cells to identify cellular genes up or downregulated by EBNA2 as well as CBF1 independent EBNA2 chromatin binding sites. Both, CBF1 independent EBNA2 target genes and chromatin binding sites are less frequent than CBF1 dependent EBNA2 functions. CBF1 independent EBNA2 binding sites are highly enriched for EBF1 binding motifs. We show that EBNA2 binds to EBF1 in CBF1 proficient and deficient B cells and requires EBF1 to bind to CBF1 independent binding sites. Our results identify EBF1 as a co-factor of EBNA2 which conveys B cell specificity to EBNA2. In order to test, if EBNA2 can exert any functions in the absence of its DNA adaptor CBF1, a microarray based genome wide screen for EBNA2 target genes in DG75 B cells that are either proficient (wt) or deficient (ko) for CBF1 was performed. CBF1 deficient DG75 cells (SM224.9) cells had been generated by gene targeting using homologous recombination in the somatic B cell line DG75. Both cell lines, the CBF1 proficient DG75 parental cell line and the CBF1 deficient somatic knock-out cell line constitutively express an estrogen receptor (ER) hormone binding domain EBNA2 fusion protein (ER/EBNA2). ER/EBNA2 is retained in the cytoplasm of the cell but is rapidly activated and translocated to the nucleus in response to estrogen. For expression profiling, DG75, DG75 CBF1 ko (SM224.9), DG75 ER/EBNA2 CBF1 wt (SM295 D6) and DG75 ER/EBNA2 CBF1 ko (SM296 D3) cells were cultured in estrogen supplemented media for 24 h, total cellular RNAs were harvested and processed for the hybridization of gene arrays. The cellular system used for this study has been published: Maier S, Santak M, Mantik A, Grabusic K, Kremmer E, Hammerschmidt W, et al. A somatic knockout of CBF1 in a human B-cell line reveals that induction of CD21 and CCR7 by EBNA-2 is strictly CBF1 dependent and that downregulation of immunoglobulin M is partially CBF1 independent. Journal of Virology. 2005 Jul;79(14):8784-92. PubMed PMID: 15994772.
Project description:Epstein-Barr virus (EBV) is a herpes virus that primarily infects, activates and immortalizes resting human B cells in vitro. EBNA2, a viral protein, is essential for the immortalization process because it transactivates a plethora of viral and cellular genes by interacting with the cellular DNA binding protein CBF1. Besides ubiquitously expressed CBF1, EBNA2 also interacts with early B cell factor (EBF) 1 which is a pioneer transcription factor specifying the B cell lineage. We have identified an alpha1-helix within EBNA2 as a critical structure for the interaction with EBF1 and in this RNA-seq experiment we wanted to see how gene regulation upon EBV infection is affected once the alpha1-helix is deleted in EBNA2 and the interaction with EBF1 is abolished.
Project description:We used genome-wide microarray comparative genomic hybridization to carry out a higher resolution evaluation of the effect of MMR competence on genomic alterations occurring in 20 cell lines and to determine if characteristic aberrations arise in MMR proficient and deficient HCT116 cells undergoing selection for methotrexate resistance. Keywords: Comparative Genomic Hybridization
Project description:Lynch syndrome and Familial colorectal cancer type X (FCCTX) are clinically diagnosed using the same criteria, but genomic differences exist between these two groups and the genomic profiles share similarities with their sporadic counterparts, mismatch repair (MMR) deficient and proficient tumors, respectively. Array-based comparative genomic hybridization was performed on 91 tumors, comprising 23 Lynch syndrome (AH), 23 FCCTX (AA), 23 sporadic MMR deficient (AM) and 22 sporadic MMR proficient tumors, in order to identify differences between Lynch syndrome and FCCTX.
Project description:Most BRCA1-deficient BLBCs carry a dysfunctional INK4-RB pathway. Thus, we have created genetically engineered mice with Brca1 loss and deletion of p16INK4A, or separately p18INK4C, to model the deficient INK4-RB signaling in human BLBC. By using these mutant mice and human BRCA1 deficient and proficient breast cancer tissues and cells, we tested if there exists a druggable target in BRCA1 deficient breast cancers.
Project description:RIP-Chip was performed on DG75-eGFP, DG75-10/12, BCBL-1, BL41, BL41 B95.8 and Jijoye using anti-human Ago2 (11A9) antibodies. Anti-BrdU antibodies were used as controls for DG75-eGFP, DG75-10/12 and BCBL-1. Total RNA was used as control for BL41, BL41 B95.8 and Jijoye. Samples were analyzed on Affymetrix Gene ST 1.0 Arrays (2 independent biological replicates / sample)
Project description:The Epstein-Barr virus nuclear antigen 2 (EBNA2) initiates and maintains the proliferation of infected B cells. In search of additional cellular strategies, that control EBNA2 function, we have performed a label-free mass spectrometry-based quantification of cellular proteins in EBNA2 immuno-precipitates and found polo-like kinase 1 (PLK1) to be bound to EBNA2. EBNA2/PLK1 complex formation is strongly enforced by EBNA2 S379 phosphorylation catalyzed by the mitotic CYCLIN B/CDK1 complex.
Project description:Total, nascent and unlabeled RNA were prepared following 1h of labeling with 100 µM 4-thiouridine and 3 replicates analyzed by Affymetrix Gene ST 1.0 arrays Transcript half-lives were determined in DG75-eGFP, DG75-10/12 and BCBL-1 based on nascent/total RNA ratios; unlabeled RNA was analyzed in addition
Project description:Notch1-IC, Notch2-IC or EBNA2 have been induced in a conditionally immortalized human B cell line (EREB2-5) in order to identify similar and unique target genes in B cells. CAT was used as a control. Experiment Overall Design: RNA was isolated at different time points after induction of Notch1-IC, Notch2-IC or EBNA2 in EREB2-5 cells. Three independent experiments were performed (except Notch1-IC at 3day).
