Specific Contributions of Cohesin-SA1 and Cohesin-SA2 to TADs and Polycomb Domains in Embryonic Stem Cells

Cell Rep. 2019 Jun 18;27(12):3500-3510.e4. doi: 10.1016/j.celrep.2019.05.078.

Abstract

Cohesin exists in two variants carrying either STAG/SA1 or SA2. Here we have addressed their specific contributions to the unique spatial organization of the mouse embryonic stem cell genome, which ensures super-enhancer-dependent transcription of pluripotency factors and repression of lineage-specification genes within Polycomb domains. We find that cohesin-SA2 facilitates Polycomb domain compaction through Polycomb repressing complex 1 (PRC1) recruitment and promotes the establishment of long-range interaction networks between distant Polycomb-bound promoters that are important for gene repression. Cohesin-SA1, in contrast, disrupts these networks, while preserving topologically associating domain (TAD) borders. The diverse effects of both complexes on genome topology may reflect two modes of action of cohesin. One, likely involving loop extrusion, establishes overall genome arrangement in TADs together with CTCF and prevents excessive segregation of same-class compartment regions. The other is required for organization of local transcriptional hubs such as Polycomb domains and super-enhancers, which define cell identity.

Keywords: CTCF; Hi-C; Hox network; PRC1; STAG1; STAG2; chromatin loop; cohesin; compartment; pluripotency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites
  • CCCTC-Binding Factor / genetics
  • CCCTC-Binding Factor / metabolism
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Chromatin / genetics
  • Chromatin / metabolism*
  • Chromosomal Proteins, Non-Histone / genetics
  • Chromosomal Proteins, Non-Histone / metabolism*
  • Enhancer Elements, Genetic
  • Gene Expression Regulation*
  • Male
  • Mice
  • Mouse Embryonic Stem Cells / cytology
  • Mouse Embryonic Stem Cells / metabolism*
  • Polycomb-Group Proteins / genetics
  • Polycomb-Group Proteins / metabolism*
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Isoforms

Substances

  • CCCTC-Binding Factor
  • Cell Cycle Proteins
  • Chromatin
  • Chromosomal Proteins, Non-Histone
  • Ctcf protein, mouse
  • Polycomb-Group Proteins
  • Protein Isoforms
  • cohesins