Molecular Mechanism For The Protection Of Centromeric Cohesion During Mitosis

Sister-chromatid cohesion mediated by the cohesin complex is fundamental for precise chromosome segregation in mitosis.Through binding the cohesin subunit Pds5,Wapl releases the bulk of cohesin from chromosome arms in prophase,whereas centromeric cohesin is protected from Wapl until anaphase onset.How the centromeric cohesion is protected is unclear.Strong centromere cohesion requires centromeric localization of the mitotic histone kinase Haspin,which is dependent on the interaction of its non-catalytic N-terminus with Pds5 B.It remains unclear how Haspin fully blocks the Wapl-Pds5 B interaction at centromeres.Here,we show that the C-terminal kinase domain of Haspin(Haspin-KD)binds and phosphorylates the YSR motif of Wapl(Wapl-YSR),thereby directly inhibiting the YSR motif-dependent interaction of Wapl with Pds5 B.Cells expressing a Wapl-binding-deficient mutant of Haspin shows centromeric cohesion defects.Forced targeting Haspin-KD to centromeres partly bypasses the need for Haspin-Pds5 B interaction in cohesion protection.Taken together,these results indicate a kinase-dependent role for Haspin in antagonizing Wapl and protecting centromeric cohesion in mitosis.The chromosomal passenger complex(CPC)is a master regulator of mitosis.CPC consists of inner centromere protein(INCENP),Survivin,Borealin,and the kinase Aurora B and plays key roles in regulating kinetochore–microtubule attachments and spindle assembly checkpoint signaling.However,the role of CPC in sister chromatid cohesion,mediated by the cohesin complex,remains incompletely understood.Here,we show that Aurora B kinase activity contributes to centromeric cohesion protection partly through promoting kinetochore localization of the kinase Bub1.Interestingly,disrupting the interaction of INCENP with heterochromatin protein 1(HP1)in HeLa cells selectively weakens cohesion at mitotic centromeres without detectably reducing the kinase activity of Aurora B.Thus,through this INCENP–HP1 interaction,the CPC also protects centromeric cohesion independently of Aurora B kinase activity.Moreover,the requirement for the INCENP-HP1 interaction in centromeric cohesion protection can be bypassed by tethering HP1 to centromeres or by depleting the cohesin release factor Wapl.We provide further evidence suggesting that the INCENP-HP1 interaction protects centromeric cohesion by promoting the centromere localization of Haspin,a protein kinase that antagonizes Wapl activity at centromeres.Taken together,we identified Aurora B kinase activity-dependent and-independent roles for the CPC in regulating centromeric cohesion during mitosis in human cells.