Project description:The discovery that enhancers are regulated transcription units, encoding eRNAs, has raised new questions about the mechanisms of their activation. Here, we report an unexpected molecular mechanism that underlies ligand-dependent enhancer activation, based on DNA nicking to relieve torsional stress from eRNA synthesis. Using dihydrotestosterone (DHT)-induced binding of androgen receptor (AR) to prostate cancer cell enhancers as a model, we show rapid recruitment, within minutes, of DNA topoisomerase I (TOP1) to a large cohort of AR-regulated enhancers. Furthermore, we show that the DNA nicking activity of TOP1 is a prerequisite for robust eRNA synthesis and enhancer activation and is kinetically accompanied by the recruitment of ATR and the MRN complex, followed by additional components of DNA damage repair machinery to the AR-regulated enhancers. Together, our studies reveal a linkage between eRNA synthesis and ligand-dependent TOP1-mediated nicking - a strategy exerting quantitative effects on eRNA expression in regulating AR-bound enhancer-dependent transcriptional programs. Genome-wide binding analysis of AR, TOP1, MRE11 in prostate cancer cell line LNCaP with or without 5alpha-dihydrotestosterone (DHT) treatment. Nascent RNA analysis by global nuclear run-on (GRO-seq) in LNCaP cells transfected with siRNA with or without DHT treatment. Distribution of transcriptionally engaged RNA Pol II in LNCaP cells with or without DHT treatment by precision nuclear run-on and sequencing (PRO-seq).
Project description:We describe, MARGE, Model-based Analysis of the Regulation of Gene Expression, a robust methodology that leverages a large library of genome-wide H3K27ac ChIP-seq profiles to predict key regulated genes and cis-regulatory regions in human or mouse. MARGE adopts a gene centric approach to define a regulatory potential that summarizes the aggregate activity of multiple cis-regulatory elements on each gene. This model is effective in describing cis-regulatory activity and, unlike the super-enhancer based approach, is highly predictive of gene expression changes in response to BET-bromodomain inhibitors. We show that linear combinations of H3K27ac defined regulatory potentials, selected from an extensive database of published H3K27ac profiles, can accurately model diverse gene sets derived from differential gene expression experiments. In addition, we demonstrate a novel semi-supervised learning approach for identifying transcription factor binding sites associated with the set of transcription factors that regulate the gene set. MARGE leverages published H3K27ac ChIP-seq data to enhance the interpretation of newly generated H3K27ac ChIP-seq profiles. MARGE can also be used to analyze gene expression studies, without the production of matched H3K27ac ChIP-seq data. Transcriptome profiling in LNCaP-abl cell line after siRNA knock down of a series of gene factors.
Project description:Androgen receptor (AR) signalling pathway plays an important role in carcinogenesis and development of prostate cancer. The involvement of microRNA (miRNA) in this process is still largely unknown. In this study, we performed a matched miRNA-mRNA time-course expression profiling to reveal androgen response in hormone-sensitive prostate cancer cells.We introduced novel statistics Response Score (RS) and Modulation Score (MS) to identify significant androgen-regulated target genes and miRNA-modulated target mRNAs. Based on the analysis, we found several novel androgen-regulated targets, which had significant androgen response in expression pattern, and were highly enriched in predicted androgen responsive elements (AREs). AR-bindings to these AREs were validated with ChIP assay. Furthermore, a set of target mRNAs involved in crucial processes of tumor progression were identified to be significantly regulated by these miRNAs. Therefore, a miRNA-mediated androgen signalling network was inferred, including three novel feedback mechanisms for AR self-modulation. In conclusion, our study provides new approaches to further miRNA regulation research and contributes novel findings into miRNA-mediated pathological effects in prostate cancer. Total RNA obtained from androgen dihydrotestosterone (DHT) subjected to LNCaP cells in vitro at 20min, 40min, 1h, 2h, 4h, 8h, 16h, 24h and 48h, compared to the control at 0h.
Project description:We present a comparative analysis of sex-specific tegument proteins of paired or virgin Schistosoma mansoni. By apply a new and highly sensitive workflow, detection of even low abundance proteins from the worm was achieved Therefore, a streptavidin-biotin affinity purification technique in combination with single pot solid-phase enhanced sample preparation was established for subsequent LC-MS/MS analysis. We were able to identify 1519 tegument proteins for male and female as to virgin and paired worms. Sex-specific proteins were screened, present in both virgin and paired adult schistosomes to reduce the impact of mating. Bioinformatic analysis revealed an involvement of female-specific tegument proteins in signaling pathways of cellular processes and antioxidant mechanisms. Male-specific proteins were found to be enriched in processes linked to phosphorylation and signal transduction. This suggests a task sharing between the sexes that might be necessary for survival in the host. Our datasets provide a basis for further studies to understand and ultimately decipher the strategies of the two worm sexes to evade the immune system.
Project description:Lysine Specific Demethylase 1 (LSD1, KDM1A) functions as a transcriptional corepressor through demethylation of histone 3 lysine 4 (H3K4), but has coactivator function on some genes through unclear mechanisms. We show that LSD1, interacting with CoREST, associates with and coactivates androgen receptor (AR) on a large fraction of androgen-stimulated genes. A subset of these AR/LSD1-associated enhancer sites have histone 3 threonine 6 phosphorylation (H3T6ph), and these sites are further enriched for androgen-stimulated genes. Significantly, despite its coactivator activity, LSD1 still mediates H3K4me2 demethylation at these androgen-stimulated enhancers. FOXA1 is also associated with LSD1 at AR regulated enhancer sites, and a FOXA1 interaction with LSD1 enhances binding of both proteins at these sites. These findings show LSD1 functions broadly as a regulator of AR function, that it maintains a transcriptional repression function at AR-regulated enhancers through H3K4 demethylation, and has a distinct AR-linked coactivator function mediated by demethylation of other substrates. Determine the role of LSD1 in androgen signaling.
Project description:We systematicaly evaluated two major factors, enzyme digestion level and fragment size, that would affect DNase-seq experiment. We found that while under- or over-digestion sigificantly decreases the DNase-seq signal, there is a broad range of suitable digestion level. In addition, we found fragment smaller than nucleosome size is optimal to identify transcription factor binding events. We tested digestion level of 5U, 25U, 50U, 75U, 100U and fragment size of 50-100bp, 100-200bp, 200-300bp
Project description:Tumor invasion into surrounding stromal tissue is a hallmark of high-grade, metastatic cancers. Oncogenic transformation of human epithelial cells in culture can be triggered by activation of v-Src kinase, resulting in increased cell motility, invasiveness and tumorigenicity and provides a valuable model for studying how changes in gene expression cause cancer phenotypes. Here, we show that epithelial cells transformed by activated Src show increased levels of DNA methylation and that the methylation inhibitor, 5-AzaC, potently blocks the increased cell motility and invasiveness induced by Src activation. A proteomic screen for chromatin regulators acting downstream of activated Src identified the replication-dependent histone chaperone CAF1 as an important factor for Src-mediated increased cell motility and invasion. We show Src causes a 5-AzaC-sensitive decrease in both mRNA and protein levels of the p150 (CHAF1A) and p60 (CHAF1B), subunits of CAF1. Depletion of CAF1 in untransformed epithelial cells using siRNA was sufficient to recapitulate the increased motility and invasive phenotypes characteristic of transformed cells without activation of Src. Maintaining high levels of CAF1 by exogenous expression suppressed the increased cell motility and invasiveness phenotypes when Src was activated. These data identify a critical role of CAF1 in the dysregulation of cell invasion and motility phenotypes seen in transformed cells and also highlight an important role for epigenetic remodeling through DNA methylation for Src-mediated induction of cancer phenotypes.
Project description:The oocyteâs capacity to complete maturation, to succeed fertilization and to reach the blastocyst stage is what defines the oocyteâs competence. The oocyte acquires this competence working closely with somatic cells of the follicle. Cumulus and granulosa cells provided support for the oocyteâs development and conversely the oocyte influence follicular cell growth and differentiation. Existing studies support the idea that follicular-stimulated hormone and luteinizing hormone play an essential role in oocyte competence acquisition through protein kinase A (PKA) and protein kinase C (PKC) signalling in granulosa cells. Therefore, human-like granulosa cells (KGN) were treated with forskolin 10 μM and phorbol 12-myristate 13-acetate 0.1 μM for 24 hours in order to process a transcriptomic analysis of differentially express genes between treatment. Over 2000 genes were founded to be differentially express at cut-off fold change of 1.5 and a p-value of 0.05. Five major upstreams, EGF, TGFB1, VEGF, FGF2 and HGF were founded to play an important role in competence acquisition thought PKA and PKC signalling. Differentially expressed targeted genes of both signalling pathways were classified in seven major ovarian functions such as PTGS2, IL8 and IL6 in inflammation, STAR, CYP11A1, CYP19A1 in steroidogenesis, VEGFC, VEGFA, CXCR4 in angiogenesis, AREG, EGFR, SPRY2 in differentiation, BAX, BCL2L12, CASP1 in apoptosis, CCND1, CCNB1, CCNB2 in division and MMP1, MMP9, TIMP1 in ovulation. Taken together, the results of this study suggest that PKA and PKC signalling potentiate their effects in some functions such as inflammation and apoptosis while some others are more specific to one or the other protein kinase like differentiation, ovulation and angiogenesis that are thought to be more PKC-dependent in human granulosa cells. 8 samples were analysed, 4 controls compared to 4 Forskolin treatments (total of 4 replicates).
Project description:The oocyteâs capacity to complete maturation, to succeed fertilization and to reach the blastocyst stage is what defines the oocyteâs competence. The oocyte acquires this competence working closely with somatic cells of the follicle. Cumulus and granulosa cells provided support for the oocyteâs development and conversely the oocyte influence follicular cell growth and differentiation. Existing studies support the idea that follicular-stimulated hormone and luteinizing hormone play an essential role in oocyte competence acquisition through protein kinase A (PKA) and protein kinase C (PKC) signalling in granulosa cells. Therefore, human-like granulosa cells (KGN) were treated with forskolin 10 μM and phorbol 12-myristate 13-acetate 0.1 μM for 24 hours in order to process a transcriptomic analysis of differentially express genes between treatment. Over 2000 genes were founded to be differentially express at cut-off fold change of 1.5 and a p-value of 0.05. Five major upstreams, EGF, TGFB1, VEGF, FGF2 and HGF were founded to play an important role in competence acquisition thought PKA and PKC signalling. Differentially expressed targeted genes of both signalling pathways were classified in seven major ovarian functions such as PTGS2, IL8 and IL6 in inflammation, STAR, CYP11A1, CYP19A1 in steroidogenesis, VEGFC, VEGFA, CXCR4 in angiogenesis, AREG, EGFR, SPRY2 in differentiation, BAX, BCL2L12, CASP1 in apoptosis, CCND1, CCNB1, CCNB2 in division and MMP1, MMP9, TIMP1 in ovulation. Taken together, the results of this study suggest that PKA and PKC signalling potentiate their effects in some functions such as inflammation and apoptosis while some others are more specific to one or the other protein kinase like differentiation, ovulation and angiogenesis that are thought to be more PKC-dependent in human granulosa cells. 8 samples were analysed, 4 controls compared to 4 Phorbol 12-myristate 13-acetate treatments (total of 4 replicates).