Heterochromatin and cohesion protection at human centromeres: the final say of a long controversy?

Mammalian centromeres are embedded within heterochromatin, a specialized chromatin assembled onto repetitive DNA that forms the primary constriction of chromosomes. In early mitosis, the bulk of cohesin dissociates from chromosomes, but a small fraction is spared at the centromere providing the ultimate linker between sister chromatid pairs, essential for their proper attachment to the mitotic spindle. Whether heterochromatin plays a role in the protection of centromere cohesion has long been controversial. In this issue of , Yi show that heterochromatin protein 1 (HP1) isoforms α and γ act redundantly to protect mitotic centromere cohesion through the recruitment of the cohesion protector Haspin 1.