The epigenetic reader Phf2 is positioned in the genome by cohesin
Ontology highlight
ABSTRACT: Eukaryotic genomes are assembled into chromatin by histones and extruded into loops by cohesin. These mechanisms control important genomic functions, but whether histones and cohesin cooperate in genome regulation is poorly understood. Here we identify Phf2, a member of the Jumonji-C family of histone demethylases, as a cohesin-interacting protein. Phf2 binds to H3K4me3 nucleosomes at active transcription start sites (TSSs) but also co-localizes with cohesin. Cohesin depletion reduces Phf2 binding at sites lacking H3K4me3, and depletion of Wapl and CTCF re-positions Phf2 together with cohesin in the genome, resulting in the accumulation of both proteins in vermicelli and cohesin islands. Conversely, Phf2 depletion reduces cohesin binding at TSSs lacking CTCF, decreases the number of short cohesin loops, but increases the length of heterochromatic B compartments. These results suggest that Phf2 is an ‘epigenetic reader’, which is translocated through the genome by cohesin-mediated DNA loop extrusion, and which recruits cohesin to active TSSs and limits the size of B compartments. These findings reveal an unexpected degree of cooperativity between epigenetic and architectural mechanisms of eukaryotic genome regulation.
Project description:Eukaryotic genomes are assembled into chromatin by histones and extruded into loops by cohesin. These mechanisms control important genomic functions, but whether histones and cohesin cooperate in genome regulation is poorly understood. Here we identify Phf2, a member of the Jumonji-C family of histone demethylases, as a cohesin-interacting protein. Phf2 binds to H3K4me3 nucleosomes at active transcription start sites (TSSs) but also co-localizes with cohesin. Cohesin depletion reduces Phf2 binding at sites lacking H3K4me3, and depletion of Wapl and CTCF re-positions Phf2 together with cohesin in the genome, resulting in the accumulation of both proteins in vermicelli and cohesin islands. Conversely, Phf2 depletion reduces cohesin binding at TSSs lacking CTCF, decreases the number of short cohesin loops, but increases the length of heterochromatic B compartments. These results suggest that Phf2 is an ‘epigenetic reader’, which is translocated through the genome by cohesin-mediated DNA loop extrusion, and which recruits cohesin to active TSSs and limits the size of B compartments. These findings reveal an unexpected degree of cooperativity between epigenetic and architectural mechanisms of eukaryotic genome regulation.
Project description:Eukaryotic genomes are assembled into chromatin by histones and extruded into loops by cohesin. These mechanisms control important genomic functions, but whether histones and cohesin cooperate in genome regulation is poorly understood. Here we identify Phf2, a member of the Jumonji-C family of histone demethylases, as a cohesin-interacting protein. Phf2 binds to H3K4me3 nucleosomes at active transcription start sites (TSSs) but also co-localizes with cohesin. Cohesin depletion reduces Phf2 binding at sites lacking H3K4me3, and depletion of Wapl and CTCF re-positions Phf2 together with cohesin in the genome, resulting in the accumulation of both proteins in vermicelli and cohesin islands. Conversely, Phf2 depletion reduces cohesin binding at TSSs lacking CTCF, decreases the number of short cohesin loops, but increases the length of heterochromatic B compartments. These results suggest that Phf2 is an ‘epigenetic reader’, which is translocated through the genome by cohesin-mediated DNA loop extrusion, and which recruits cohesin to active TSSs and limits the size of B compartments. These findings reveal an unexpected degree of cooperativity between epigenetic and architectural mechanisms of eukaryotic genome regulation.
Project description:Eukaryotic genomes are assembled into chromatin by histones and extruded into loops by cohesin. These mechanisms control important genomic functions, but whether histones and cohesin cooperate in genome regulation is poorly understood. Here we identify Phf2, a member of the Jumonji-C family of histone demethylases, as a cohesin-interacting protein. Phf2 binds to H3K4me3 nucleosomes at active transcription start sites (TSSs) but also co-localizes with cohesin. Cohesin depletion reduces Phf2 binding at sites lacking H3K4me3, and depletion of Wapl and CTCF re-positions Phf2 together with cohesin in the genome, resulting in the accumulation of both proteins in vermicelli and cohesin islands. Conversely, Phf2 depletion reduces cohesin binding at TSSs lacking CTCF, decreases the number of short cohesin loops, but increases the length of heterochromatic B compartments. These results suggest that Phf2 is an ‘epigenetic reader’, which is translocated through the genome by cohesin-mediated DNA loop extrusion, and which recruits cohesin to active TSSs and limits the size of B compartments. These findings reveal an unexpected degree of cooperativity between epigenetic and architectural mechanisms of eukaryotic genome regulation.
Project description:Mammalian genomes are organized into compartments, topologically-associating domains (TADs) and loops to facilitate gene regulation and other chromosomal functions. Compartments are formed by nucleosomal interactions, but how TADs and loops are generated is unknown. It has been proposed that cohesin forms these structures by extruding loops until it encounters CTCF, but direct evidence for this hypothesis is missing. Here we show that cohesin suppresses compartments but is essential for TADs and loops, that CTCF defines their boundaries, and that WAPL and its PDS5 binding partners control the length of chromatin loops. In the absence of WAPL and PDS5 proteins, cohesin passes CTCF sites with increased frequency, forms extended chromatin loops, accumulates in axial chromosomal positions (vermicelli) and condenses chromosomes to an extent normally only seen in mitosis. These results show that cohesin has an essential genome-wide function in mediating long-range chromatin interactions and support the hypothesis that cohesin creates these by loop extrusion, until it is delayed by CTCF in a manner dependent on PDS5 proteins, or until it is released from DNA by WAPL.
Project description:CCCTC-binding factor (CTCF) is an architectural protein involved in the three-dimensional organization of chromatin. In this study, we systematically assayed the 3D genomic contact profiles of hundreds of CTCF binding sites in multiple tissues with high-resolution 4C-seq. We find both developmentally stable and dynamic chromatin loops. As recently reported, our data also suggest that chromatin loops preferentially form between CTCF binding sites oriented in a convergent manner. To directly test this, we used CRISPR-Cas9 genome editing to delete core CTCF binding sites in three loci, including the CTCF site in the Sox2 super-enhancer. In all instances, CTCF and cohesin recruitment were lost, and chromatin loops with distal CTCF sites were disrupted or destabilized. Re-insertion of oppositely oriented CTCF recognition sequences restored CTCF and cohesin recruitment, but did not re-establish chromatin loops. We conclude that CTCF binding polarity plays a functional role in the formation of higher order chromatin structure. 4C-seq was performed on a large number of viewpoints in E14 embryonic stem cells, neural precursor cells and primary fetal liver cells
Project description:Cohesin stalling at CTCF binding sites represents one of the main principles of interphase chromosome organization. In the current studies, we dissect the role of cohesin and CTCF, both alone and in combination, in 3D genome organization by depleting these proteins using acute protein degradation techniques. By systematic examination of interactomic, epigenomic and transcriptomic changes using various sequencing techniques, our studies reveal the functions of cohesin and CTCF in mediating the formation of chromatin loops, topologically associating domains, chromosome compartments and nuclear lamina associating domains. Our studies describe fundamental principles of how the architectural proteins contribute to genome folding at multiple genomic scales and transcriptional regulation.
Project description:Cohesin stalling at CTCF binding sites represents one of the main principles of interphase chromosome organization. In the current studies, we dissect the role of cohesin and CTCF, both alone and in combination, in 3D genome organization by depleting these proteins using acute protein degradation techniques. By systematic examination of interactomic, epigenomic and transcriptomic changes using various sequencing techniques, our studies reveal the functions of cohesin and CTCF in mediating the formation of chromatin loops, topologically associating domains, chromosome compartments and nuclear lamina associating domains. Our studies describe fundamental principles of how the architectural proteins contribute to genome folding at multiple genomic scales and transcriptional regulation.
Project description:Cohesin stalling at CTCF binding sites represents one of the main principles of interphase chromosome organization. In the current studies, we dissect the role of cohesin and CTCF, both alone and in combination, in 3D genome organization by depleting these proteins using acute protein degradation techniques. By systematic examination of interactomic, epigenomic and transcriptomic changes using various sequencing techniques, our studies reveal the functions of cohesin and CTCF in mediating the formation of chromatin loops, topologically associating domains, chromosome compartments and nuclear lamina associating domains. Our studies describe fundamental principles of how the architectural proteins contribute to genome folding at multiple genomic scales and transcriptional regulation.
Project description:Cohesin stalling at CTCF binding sites represents one of the main principles of interphase chromosome organization. In the current studies, we dissect the role of cohesin and CTCF, both alone and in combination, in 3D genome organization by depleting these proteins using acute protein degradation techniques. By systematic examination of interactomic, epigenomic and transcriptomic changes using various sequencing techniques, our studies reveal the functions of cohesin and CTCF in mediating the formation of chromatin loops, topologically associating domains, chromosome compartments and nuclear lamina associating domains. Our studies describe fundamental principles of how the architectural proteins contribute to genome folding at multiple genomic scales and transcriptional regulation.
Project description:Cohesin stalling at CTCF binding sites represents one of the main principles of interphase chromosome organization. In the current studies, we dissect the role of cohesin and CTCF, both alone and in combination, in 3D genome organization by depleting these proteins using acute protein degradation techniques. By systematic examination of interactomic, epigenomic and transcriptomic changes using various sequencing techniques, our studies reveal the functions of cohesin and CTCF in mediating the formation of chromatin loops, topologically associating domains, chromosome compartments and nuclear lamina associating domains. Our studies describe fundamental principles of how the architectural proteins contribute to genome folding at multiple genomic scales and transcriptional regulation.