Centromeric Aurora-B activation requires TD-60, microtubules, and substrate priming phosphorylation

The chromosome passenger complex ( CPC) controls chromosome congression, kinetochore- microtubule attachments, and spindle checkpoint signaling during mitosis. Aurora- B kinase is the catalytic subunit of the CPC. To understand how a single kinase can regulate such diverse events, we have investigated the activation of Aurora- B and describe two distinct activation mechanisms. First, Aurora- B activation in vitro requires two cofactors, telophase disc-60kD ( TD-60) and microtubules. TD-60 is critical to localize both the CPC and Haspin kinase activity to centromeres and thus regulates Aurora- B at several levels. Second, Aurora- B substrates can inhibit kinase activation, and this is relieved by phosphorylation of these substrates by the centromeric kinases Plk1 and Haspin. These regulatory mechanisms suggest models for phosphorylation by Aurora- B of centromeric substrates at unaligned chromosomes and merotelic attachments.