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: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:Condensins are conserved multi-subunit protein complexes that participate in eukaryotic genome organization. Well known for their role in mitotic chromosome condensation, condensins have recently emerged as integral components of diverse interphase processes. Recent evidence shows that condensins are involved in chromatin organization, gene expression, and DNA repair and indicates similarities between the interphase and mitotic functions of condensin. Recent work has enhanced our knowledge of how chromatin architecture is dynamically regulated by condensin to impact essential cellular processes.
Project description:The condensin complex has been implicated in the higher-order organization of mitotic chromosomes in a host of model eukaryotes from yeasts to flies and vertebrates. Although chromosomes paradoxically appear to condense in condensin mutants, chromatids are not properly resolved, resulting in chromosome segregation defects during anaphase. We have examined the role of different condensin complex components in interphase chromatin function by examining the effects of various condensin mutations on position-effect variegation in Drosophila melanogaster. Surprisingly, most mutations affecting condensin proteins were often found to result in strong enhancement of variegation in contrast to what might be expected for proteins believed to compact the genome. This suggests either that the role of condensin proteins in interphase differs from their expected role in mitosis or that the way we envision condensin's activity needs to be modified to accommodate alternative possibilities.