Project description:An emerging theme of gene regulation is the involvement of architectural chromosomal molecules in transcription control. Condensins are critical regulators of mitotic chromosomes, but their interphase chromatin localization and functions remain poorly understood. Here we report that both the condensin I and condensin II complexes exhibit an unexpected, dramatic 17-?-estradiol-induced preferential recruitment to oestrogen receptor ? (ER-?)-bound active enhancers in interphase breast cancer cells, exhibiting non-canonical interaction with ER-? distinct from classic cofactors. Condensins prove to positively regulate ligand-dependent gene and eRNA transcription by modulating a binding equilibrium of enhancer-associated coactivators/corepressors, including p300 and RIP140. This activity was achieved by the condensin-dependent recruitment of an E3 ubiquitin ligase, HECTD1, to active enhancers, where it polyubiquitinates and dismisses corepressor RIP140 to stimulate eRNA transcription. Collectively, our results reveal an important, unanticipated transcriptional role of interphase condensins in modulating enhancer activation, providing new insights into enhancer function in the regulated transcriptional programs
Project description:An emerging theme of gene regulation is the involvement of architectural chromosomal molecules in transcription control. Condensins are critical regulators of mitotic chromosomes, but their interphase chromatin localization and functions remain poorly understood. Here we report that both the condensin I and condensin II complexes exhibit an unexpected, dramatic 17-β-estradiol-induced preferential recruitment to oestrogen receptor α (ER-α)-bound active enhancers in interphase breast cancer cells, exhibiting non-canonical interaction with ER-α distinct from classic cofactors. Condensins prove to positively regulate ligand-dependent gene and eRNA transcription by modulating a binding equilibrium of enhancer-associated coactivators/corepressors, including p300 and RIP140. This activity was achieved by the condensin-dependent recruitment of an E3 ubiquitin ligase, HECTD1, to active enhancers, where it polyubiquitinates and dismisses corepressor RIP140 to stimulate eRNA transcription. Collectively, our results reveal an important, unanticipated transcriptional role of interphase condensins in modulating enhancer activation, providing new insights into enhancer function in the regulated transcriptional programs
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:Condensin complexes are highly conserved for chromosome compaction to ensure their faithful segregation in mitosis. However, little is known about the role of condensin complexes in interphase. Condensins exists in two complexes, condensins I and II, in higher eukayotic cells. During interphase, condensin II is predominantly localized in the nucleus throughout the cell cycle, whereas condensin I is localized at the cytoplasm in interphase. The distinct localization patterns suggest that condensin II, but not condensin I, may contribute to genome organization in interphase. Our results suggest that condensin II is associated with TFIIIC complex in humans.
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.
Project description:Condensin complexes are highly conserved for chromosome compaction to ensure their faithful segregation in mitosis. However, little is known about the role of condensin complexes in interphase. Condensins exists in two complexes, condensins I and II, in higher eukayotic cells. During interphase, condensin II is predominantly localized in the nucleus throughout the cell cycle, whereas condensin I is localized at the cytoplasm in interphase. The distinct localization patterns suggest that condensin II, but not condensin I, may contribute to genome organization in interphase. Our results suggest that condensin II is associated with TFIIIC complex in vivo. The aim of these experiments is to unravel the dependency of each other on binding to chromatin.
Project description:Condensin complexes have been proposed to play a prominent role in interphase chromatin organization and control of gene expression. Here, we report that the deletion of the central condensin II kleisin subunit Ncaph2 in differentiated mouse hepatocytes does not lead to significant changes in chromosome organization or in gene expression. Both observations challenge current views that implicate condensin in interphase chromosomal domain formation and in enhancer-promoter interactions. Instead, we suggest that the previously reported effects of condensin perturbation may result from their structural role during mitosis, which might indirectly impact the re-establishment of interphase chromosomal architecture after cell division.