TIF1β association with HP1 is essential for post-gastrulation development, but not for Sertoli cell functions during spermatogenesis

► We have assessed the functional relevance of the interaction between TIF1β and HP1. ► We have mutated TIF1β HP1 HP1box in mice either in germ-line cells or in Sertoli cells. ► This mutation leads to arrest during embryonic development and impaired spermatogenesis. ► These functions correlate with TIF1β association with heterochromatin. ► We conclude that TIF1β/HP1 interaction is essential for most TIF1β functions in vivo.