The SUMO protease SENP7 is a critical component to ensure HP1 enrichment at pericentric heterochromatin

SUMOylation promotes targeting of HP1 alpha to pericentric heterochromatin. Here we identify the SUMO-specific protease SENP7 in mouse as a maintenance factor for HP1 alpha accumulation at this location. SENP7 interacts directly with HP1 alpha, localizes at HP1-enriched pericentric domains and can deconjugate SUMOylated HP1 alpha in vivo. Depletion of SENP7 delocalizes HP1 alpha from pericentric heterochromatin without affecting H3K9me3 levels. We propose that following targeting of HP1 alpha, a subsequent deSUMOylation event enables HP1 alpha retention at these domains.