Project description:Hundreds of DNA replication forks functioning simultaneously are essential for timely DNA duplication, but the organization of replication forks are poorly understood in mammalian cells. Here, we developed a replication-enriched in situ HiC (Repli-HiC) method to capture chromatin contacts located adjacent to replication forks and found two types of fountain-like chromatin contacts at thousands of loci. Interactions within fountain-spanning regions are confirmed by q3C-seq analysis of different stages of S phase cells.
2024-03-04 | GSE230613 | GEO
Project description:Fountain structure after DNA replication
Project description:Exercise late in life mitigates skeletal muscle epigenetic aging, providing evidence that physical activity is a "fountain of youth".
Project description:The glucocorticoid receptor (GR) recruits many coregulators via the well characterized AF2 interaction surface in the GR ligand binding domain, but LIM domain coregulator Hic-5 binds to the relatively uncharacterized tau2 activation domain in the hinge region of GR. Requirement of Hic-5 for glucocorticoid-regulated gene expression in U2OS osteosarcoma cells was defined by Hic-5 depletion and global gene expression analysis. Hic-5 depletion had selective and dramatic effects, positive and negative, on both activation and repression of GR target genes. For some hormone-induced genes, Hic-5 facilitated recruitment of the Mediator complex and RNA polymerase II. In contrast, many genes were not regulated by hormone until Hic-5 was depleted. On these genes Hic-5 acted at a very early step of the regulatory process, preventing efficient GR binding on enhancers, chromatin remodeling, and thus preventing glucocorticoid-driven transcriptional regulation. Overall, Hic-5 has selective and diverse roles on GR target genes, functioning as coactivator on some genes and corepressor on others, and either facilitating or opposing the glucocorticoid-driven actions of GR. Hic-5 exhibits multiple mechanisms of action, either regulating GR binding to DNA and chromatin remodeling, or facilitating later steps in transcription complex assembly. We investigate the relationship between GR and Hic5 and identify classes of genes that respond differently when cells are induced with hormone and when Hic5 is knocked down We knock down Hic-5 (TGFB1I1) in U2OS cells using siRNA (siHic5_2) along with nonspecific siRNA (shNS) and assay gene expression changes at 4 different time points of hormone treatment. We also include non-infected control (NI) as a second control at each time point.
Project description:The glucocorticoid receptor (GR) recruits many coregulators via the well characterized AF2 interaction surface in the GR ligand binding domain, but LIM domain coregulator Hic-5 binds to the relatively uncharacterized tau2 activation domain in the hinge region of GR. Requirement of Hic-5 for glucocorticoid-regulated gene expression in U2OS osteosarcoma cells was defined by Hic-5 depletion and global gene expression analysis. Hic-5 depletion had selective and dramatic effects, positive and negative, on both activation and repression of GR target genes. For some hormone-induced genes, Hic-5 facilitated recruitment of the Mediator complex and RNA polymerase II. In contrast, many genes were not regulated by hormone until Hic-5 was depleted. On these genes Hic-5 acted at a very early step of the regulatory process, preventing efficient GR binding on enhancers, chromatin remodeling, and thus preventing glucocorticoid-driven transcriptional regulation. Overall, Hic-5 has selective and diverse roles on GR target genes, functioning as coactivator on some genes and corepressor on others, and either facilitating or opposing the glucocorticoid-driven actions of GR. Hic-5 exhibits multiple mechanisms of action, either regulating GR binding to DNA and chromatin remodeling, or facilitating later steps in transcription complex assembly. We investigate the relationship between GR and Hic5 and identify classes of genes that respond differently when cells are induced with hormone and when Hic5 is knocked down We knock down Hic-5 (TGFB1I1) in U2OS cells using two different siRNA (siHic5_2 and siHic5_5) along with nonspecific siRNA (shNS) and assay gene expression changes at 4 different time points of hormone treatment. We also include non-infected control (NI) as a second control at each time point.
Project description:The resolution limit of chromatin conformation capture methodologies (3Cs) has restrained their application in detection of fine-level chromatin structure mediated by cis-regulatory elements (CREs). Here we report two 3C-derived methods, Tri-4C and Tri-HiC, utilizing mult-restriction enzyme digestions capable of achieveing ultrafine genome digestion for targeted and global chromatin interaction mapping, respectively, at a one hundred basepair resolution. Tri-4C identified loops associated with CREs including those involving regulatory elements devoid of typical epigenomic marks, quantifatively revealing alterations in interaction networks underlying dynamic gene control. Tri-HiC successfully uncovers fine-gage enhancer:promoter (E:P) loops at genome-wide level, identifying > 20-fold more CRE loops than in situ HiC. In addition to refined loop detection, Tri-HiC also reveals interaction stripes and contact domain insulation from promoters and enhancers, revealing their loop extrusion behaviors resembling the topologically-associated domain (TAD) boundaries. Tri-4C and Tri-HiC provide robust approaches to achieve the high resolution interactome maps required for characterizing fine-gage regulatory chromatin interactions in analysis of development, homeostasis and disease.