Issue highlights

Heterochromatin enriched in histone H3 lysine 9 methylation (H3K9me) and HP1 proteins coats chromosomal domains throughout the eukaryotic genome to regulate gene expression and maintain genome stability. How heterochromatin assembly mechanisms are coordinated with other chromosomal processes remains unknown. Folco et al. find that loss of cohesin-associated Pds5 enriched throughout heterochromatin domains or the cohesin acetyltransferase Eso1 cause heterochromatic silencing defects. Although cohesin itself is not required for heterochromatin assembly, unacetylated cohesin in cells lacking Pds5 or Eso1 impedes heterochromatin maintenance mechanisms. These findings highlight how heterochromatin assembly can be hindered by a failure in the intricate coordination of fundamental chromosomal activities.