Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Ligand-Dependent Enhancer Activation Regulated by Topoisomerase-I Activity

ABSTRACT: 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).

ORGANISM(S): Homo sapiens

SUBMITTER: Michael Rosenfeld

PROVIDER: E-GEOD-63202 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Ligand-dependent enhancer activation regulated by topoisomerase-I activity.

Puc Janusz J Kozbial Piotr P Li Wenbo W Tan Yuliang Y Liu Zhijie Z Suter Tom T Ohgi Kenneth A KA Zhang Jie J Aggarwal Aneel K AK Rosenfeld Michael G MG

Cell 20150122 3

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 topoisomer ...[more]

PMID: 25619691

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Project description:While thousands of long non-coding RNAs (lncRNAs) are expressed in higher eukaryotes, the potential regulatory roles of lncRNAs in regulated gene transcription programs remain rather poorly understood. Here, we report that two lncRNAs highly overexpressed in aggressive prostate cancer, PRNCR1 and PCGEM1, bind successively to the androgen receptor (AR) and strongly enhance both ligand-dependent and ligand-independent AR-mediated gene activation programs and proliferation in prostate cancer cells. Binding of PRNCR1 to the C-terminally acetylated AR on enhancers and its association with DOT1L appear to be required for recruitment of the second lncRNA, PCGEM, to the N-terminally methylated AR. Unexpectedly, recognition of the H3K4me3 promoter mark by the PHD finger-domain of Pygopus2, recruited by PCGEM1, proves to enhance selective looping of AR-bound enhancers to target gene promoters in these cells, revealing a novel aspect of ligand-induced enhancer-promoter interactions. In “resistant” prostate cancer cells, these overexpressed lncRNAs can interact with, and are required for the robust activation of both truncated and full length AR, causing DHT-independent activation of the AR transcriptional program and cell proliferation. Conditionally-expressed short hairpin RNA (shRNA)-mediated targeting of these lncRNAs in these resistant cancer cell lines strongly suppressed xenograft growth in vivo. Together, these results suggest that these overexpressed lncRNAs can potentially serve as a required component of castration-resistance in prostatic tumors. Global Run On (GRO) assay followed by high throughput sequencing (GRO-seq); after knocking-down lincRNAs PCGEM1 and PRNCR1. LNCaP cells were grown to 30-50% confluence and siRNA/ASO transfections were carried out using Lipofectamine 2000 (Invitrogen) according to the manufacturer’s instructions. Control samples were transfected with scramble ASO and control siRNA, respectively. On the following day of transfection, the cells were cultured in UltraCULTURE (Phenol red free) + 5% Charcoal Dextran Stripped (CDS) serum for 48 hours. For androgen induction, we treat cells with DHT from a 100 uM stock in 70% ethanol to a final concentration of 100 nM for 1 hour Scramble ASO, -DHT Scramble ASO, +DHT PRNCR1 ASO, -DHT PRNCR1 ASO, +DHT PCGEM1 ASO, -DHT PCGEM1 ASO, +DHT

Project description:While thousands of long non-coding RNAs (lncRNAs) are expressed in higher eukaryotes, the potential regulatory roles of lncRNAs in regulated gene transcription programs remain rather poorly understood. Here, we report that two lncRNAs highly overexpressed in aggressive prostate cancer, PRNCR1 and PCGEM1, bind successively to the androgen receptor (AR) and strongly enhance both ligand-dependent and ligand-independent AR-mediated gene activation programs and proliferation in prostate cancer cells. Binding of PRNCR1 to the C-terminally acetylated AR on enhancers and its association with DOT1L appear to be required for recruitment of the second lncRNA, PCGEM, to the N-terminally methylated AR. Unexpectedly, recognition of the H3K4me3 promoter mark by the PHD finger-domain of Pygopus2, recruited by PCGEM1, proves to enhance selective looping of AR-bound enhancers to target gene promoters in these cells, revealing a novel aspect of ligand-induced enhancer-promoter interactions. In “resistant” prostate cancer cells, these overexpressed lncRNAs can interact with, and are required for the robust activation of both truncated and full length AR, causing DHT-independent activation of the AR transcriptional program and cell proliferation. Conditionally-expressed short hairpin RNA (shRNA)-mediated targeting of these lncRNAs in these resistant cancer cell lines strongly suppressed xenograft growth in vivo. Together, these results suggest that these overexpressed lncRNAs can potentially serve as a required component of castration-resistance in prostatic tumors. Global Run On (GRO) assay followed by high throughput sequencing (GRO-seq); after knocking down PYGO2 LNCaP cells were grown to 30-50% confluence and siRNA/ASO transfections were carried out using Lipofectamine 2000 (Invitrogen) according to the manufacturer’s instructions. Control samples were transfected with scramble ASO and control siRNA, respectively. On the following day of transfection, the cells were cultured in UltraCULTURE (Phenol red free) + 5% Charcoal Dextran Stripped (CDS) serum for 48 hours. For androgen induction, we treat cells with DHT from a 100 uM stock in 70% ethanol to a final concentration of 100 nM for 1 hour Control siRNA, -DHT Control siRNA, +DHT Pygo2 siRNA, -DHT Pygo2 siRNA, +DHT

Dataset Information

Ligand-Dependent Enhancer Activation Regulated by Topoisomerase-I Activity

Publications

Ligand-dependent enhancer activation regulated by topoisomerase-I activity.

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