| Autor: |
Cavalheiro GR; European Molecular Biology Laboratory (EMBL), Genome Biology Unit, D-69117 Heidelberg, Baden-Württemberg, Germany.; Collaboration for Joint PhD Degree between EMBL and Heidelberg University, Faculty of Biosciences, Baden-Württemberg, Germany., Girardot C; European Molecular Biology Laboratory (EMBL), Genome Biology Unit, D-69117 Heidelberg, Baden-Württemberg, Germany., Viales RR; European Molecular Biology Laboratory (EMBL), Genome Biology Unit, D-69117 Heidelberg, Baden-Württemberg, Germany., Pollex T; European Molecular Biology Laboratory (EMBL), Genome Biology Unit, D-69117 Heidelberg, Baden-Württemberg, Germany., Cao TBN; European Molecular Biology Laboratory (EMBL), Genome Biology Unit, D-69117 Heidelberg, Baden-Württemberg, Germany., Lacour P; European Molecular Biology Laboratory (EMBL), Genome Biology Unit, D-69117 Heidelberg, Baden-Württemberg, Germany.; École Normale Supérieure, 45 rue d'Ulm, 75005 Paris, France., Feng S; European Molecular Biology Laboratory (EMBL), Genome Biology Unit, D-69117 Heidelberg, Baden-Württemberg, Germany., Rabinowitz A; European Molecular Biology Laboratory (EMBL), Genome Biology Unit, D-69117 Heidelberg, Baden-Württemberg, Germany., Furlong EEM; European Molecular Biology Laboratory (EMBL), Genome Biology Unit, D-69117 Heidelberg, Baden-Württemberg, Germany. |
| Abstrakt: |
The boundaries of topologically associating domains (TADs) are delimited by insulators and/or active promoters; however, how they are initially established during embryogenesis remains unclear. Here, we examined this during the first hours of Drosophila embryogenesis. DNA-FISH confirms that intra-TAD pairwise proximity is established during zygotic genome activation (ZGA) but with extensive cell-to-cell heterogeneity. Most newly formed boundaries are occupied by combinations of CTCF, BEAF-32, and/or CP190. Depleting each insulator individually from chromatin revealed that TADs can still establish, although with lower insulation, with a subset of boundaries (~10%) being more dependent on specific insulators. Some weakened boundaries have aberrant gene expression due to unconstrained enhancer activity. However, the majority of misexpressed genes have no obvious direct relationship to changes in domain-boundary insulation. Deletion of an active promoter (thereby blocking transcription) at one boundary had a greater impact than deleting the insulator-bound region itself. This suggests that cross-talk between insulators and active promoters and/or transcription might reinforce domain boundary insulation during embryogenesis. |
