Project description:Basal-like breast cancer (BBC) is a highly aggressive form of breast cancer that exhibits extremely high levels of genetic complexity and yet a relatively uniform transcriptional program. We postulate that BBC might be highly dependent on uninterrupted transcription of a key set of genes within this gene expression program and might therefore be exceptionally sensitive to inhibitors of transcription. Utilizing a novel kinase inhibitor and CRISPR/Cas9-mediated gene editing, we show here that basal but not luminal breast cancer cells are exceptionally dependent on CDK7, a transcriptional cyclin-dependent kinase. BBC cells are unique in their dependence on this transcriptional CDK and suffer apoptotic cell death upon CDK7 inhibition. An “Achilles cluster” of BBC-specific genes are extremely sensitive to CDK7 inhibition and frequently associated with super-enhancers. We conclude that CDK7 mediates transcriptional addiction to a vital cluster of genes in BBC and CDK7 inhibition may be useful therapy for this challenging cancer. ChIP-Seq for H3K27ac in basal-like breast cancer and luminal-like breast cancer cell lines
Project description:We performed ChIP-seq in the GR18 cell line (derived from U2OS ATTC:HTB-96, stably transfected with an expression construct for GR), upon glucocorticoid (dexamethasone)treatment for 90 minutes. Cells were cross-linked with 1% formaldehyde for 3 minutes.
Project description:Retinoic acid (RA) triggers growth-suppressive effects in tumor cells and therefore RA and its synthetic analogs have great potential as anti-carcinogenic agents. RA effects are mediated by retinoic acid receptors (RARs), which regulate gene expression in an RA-dependent manner. To define the genetic network regulated by RARs in breast cancer cells, we identified RAR genomic targets using chromatin immunoprecipitation and expression analysis in a model breast cancer cell line MCF-7. Furthermore, we identified genomic binding sites for two putative RAR coregulators FoxA1 and GATA3. Keywords: ChIP-Chip Analysis This series contains ChIP-Chip raw data for four transcription factors (RARA, RARG, FoxA1 and GATA3) in MCF-7 cells. All the experiments are done in triplicates. We mapped the binding sites of RARA, RARG and GATA3 in the bacterial artificial chromosome (BAC) transgenic MCF7 cells in which we tagged the transcription factors with a modified LAP (localization and affinity purification) tag containing green fluorescent protein (GFP). Goat anti-GFP (raised against His-tagged full-length eGFP and affinity-purified with GST-tagged full-length eGFP) was used to perform ChIP experiments in those transgenic lines. To map the binding sites of RARs, MCF7 Cells were hormone-deprived for 3 days and then were treated with 100 nM AM580 (RARA-selective agonist) or 100 nM CD437 (RARG-selective agonist) for 1 hour at 80% confluence. FoxA1 binding sites were mapped using goat anti-FoxA1 antibodies (Abcam: ab5089). Control data include Input from MCF-7 cells. ChIP-Chip experiments with eGFP antibody in wide type MCF-7 cells are used to control eGFP antibody non-specific binding.
Project description:Evolution of the mammalian sex chromosomes has resulted in a heterologous X and Y pair, where the Y chromosome has lost most of its genes. Hence, there is a need for X-linked gene dosage compensation between XY males and XX females. In placental mammals, this is achieved by random inactivation of one X chromosome (XCI) in all female somatic cells. Up-regulation of Xist transcription on the future inactive X chromosome (Xi) acts against Tsix antisense transcription, and spreading of Xist RNA in cis triggers epigenetic changes leading to XCI. Previously, we have shown that the X-encoded E3 ubiquitin ligase RNF12 is up-regulated in differentiating mouse embryonic stem cells (ESCs) and activates Xist transcription and XCI. Here, we have identified the pluripotency factor REX1 as a key target of RNF12 in the XCI mechanism. RNF12 causes ubiquitination and proteasomal degradation of REX1, and Rnf12 knockout mouse ESCs show an increased level of REX1. Using ChIP-seq, REX1 binding sites were detected in Xist and Tsix regulatory regions. Over-expression of REX1 in female ESCs was found to inhibit Xist transcription and XCI, whereas male Rex1+/- ESCs showed ectopic XCI. From this, we propose that RNF12 causes REX1 breakdown through dose-dependent catalysis, thereby representing an important pathway to initiate XCI. Rex1 and Xist are present only in placental mammals, which points to co-evolution of these two genes and XCI. 2 (one control one pulldown) samples
Project description:Under current models for signal-dependent transcription in eukaryotes, DNA-binding activator proteins regulate the recruitment of RNA polymerase II (Pol II) to a set of target promoters. Yet, recent studies, as well as our results herein, show that Pol II is widely distributed (i.e., "preloaded") at the promoters of many genes prior to specific signaling events. How Pol II recruitment and Pol II preloading fit within a unified model of gene regulation is unclear. In addition, the mechanisms through which cellular signals activate preloaded Pol II across mammalian genomes remain largely unknown. Here we show that the predominant genomic outcome of estrogen signaling is the post-recruitment regulation of Pol II activity through phosphorylation, rather than recruitment of Pol II. Furthermore, we show that negative elongation factor (NELF) binds to estrogen target promoters in conjunction with preloaded Pol II and represses gene expression until the appropriate signal is received. Finally, our studies reveal that the estrogen-dependent activation of preloaded Pol II facilitates rapid transcriptional and post-transcriptional responses which play important physiological roles in regulating estrogen signaling itself. Our results reveal a broad use of post-recruitment Pol II regulation by the estrogen signaling pathway, a mode of regulation that is likely to apply to a wide variety of signal-regulated pathways. ChIP-chip analysis for RNA Pol II, Ser5 phosphorylated RNA Pol II and NELF-A in MCF7 breast cancer cells.
Project description:We report maps of H3K4me3 and H3ac - activiting expression histone modifications in C6 rat glioma cells. The data was obtained using whole genome high throughput technology. The sequencing was performed on HiSeq Ilumina platform. Examination of H3K4me3 histone modification and H3ac histone modification in C6 rat glioma cell line
Project description:MacroH2A1 ChIP-chip was performed on custom Nimblegen genomic tiling arrays, to understand the genomic binding patterns of this histone variant and its relationship to gene expression Keywords: ChIP-chip Two macroH2A biological replicates are included. An H3 ChIP-chip sample is included as a control
Project description:Background: The androgen receptor (AR) is a tumor suppressor in estrogen receptor (ER) positive breast cancer, a role sustained in some ER negative breast cancers. Key factors dictating AR genomic activity in a breast context are largely unknown. Herein, we employed an unbiased chromatin immunoprecipitation-based proteomic technique to identify endogenous AR interacting co-regulatory proteins in ER positive and negative models of breast cancer to gain new insight into mechanisms of AR signaling in this disease. Results: The DNA-binding factor GATA3 is identified and validated as a novel AR interacting protein in breast cancer cells irrespective of ER status. AR activation by the natural ligand 5α-dihydrotestosterone (DHT) increases nuclear AR-GATA3 interactions, resulting in AR-dependent enrichment of GATA3 chromatin binding at a sub-set of genomic loci. Silencing GATA3 reduces but does not prevent AR DNA binding and transactivation of genes associated with AR/GATA3 co-occupied loci, indicating a co-regulatory role for GATA3 in AR signaling. DHT-induced AR/GATA3 binding coincides with upregulation of luminal differentiation genes, including EHF and KDM4B, established master regulators of a breast epithelial cell lineage. These findings are validated in a patient-derived xenograft model of breast cancer. Interaction between AR and GATA3 is also associated with AR-mediated growth inhibition in ER positive and ER negative breast cancer.
Project description:Mutations in the human RMRP gene cause Cartilage Hair Hypoplasia (CHH), an autosomal recessive disorder characterized by skeletal abnormalities and impaired T-cell activation. RMRP encodes a non-coding RNA, which forms the core of the RNase MRP ribonucleoprotein complex. In budding yeast, RMRP cleaves a specific site in the pre-ribosomal RNA (pre-rRNA) during ribosome synthesis. CRISPR-mediated disruption of RMRP in human cells lines caused growth arrest, with pre-rRNA accumulation. Here, we analyzed disease-relevant primary cells, showing that mutations in RMRP impair mouse T cell activation and delay pre-rRNA processing. Analysis of pre-rRNA processing in patient-derived human fibroblasts with CHH-linked mutations showed a similar pattern of processing delay. Human cells engineered with the most common CHH mutation (70AG in RMRP) show specifically impaired pre-rRNA processing, resulting in reduced mature rRNA and a reduced ratio of cytosolic to mitochondrial ribosomes. Moreover, the 70AG mutation caused a reduction in intact RNase MRP complexes. Together, these results indicate that CHH is a ribosomopathy, and the first human disorder of rRNA processing to be described.
Project description:JNK1 ChIP-chip and ER-alpha ChIP-chip were performed on NimbleGen genomic tiling arrays to understand the genomic binding patterns of this MAP kinase and receptor and their relationship to gene expression. ChIP-chip analysis of JNK1 occupancy at promoters before and after estrogen treatment. 2 biological replicates (rep1 and rep2, rep3A and rep3B), 2 technical replicates each. ChIP-chip analysis of ER-alpha occupancy at promoters before and after estrogen treatment. 2 biological replicates, 2 technical replicates for one of the replicates (1 and 2).