Cell Biology

Divisive Tension

Science Signaling  10 Mar 2009:
Vol. 2, Issue 61, pp. ec93
DOI: 10.1126/scisignal.261ec93

Chromosome attachments to the mitotic spindle are regulated by tension across the centromere, which ensures accurate chromosome segregation. Spindle microtubules can bind chromosomes at the kinetochore in different configurations, but only bi-oriented attachments can support accurate chromosome segregation. Tension across the centromere distinguishes correct and incorrect attachments, but how tension is sensed to regulate attachments is unclear. The mitotic kinase Aurora B is a key regulator of kinetochore-microtubule attachments, and phosphorylation of Aurora B substrates at kinetochores reduces microtubule affinity. Liu et al. tested to see whether a tension-sensitive mechanism regulates Aurora B activity. Instead, their results suggest that Aurora B kinase activity is not directly regulated by tension but that phosphorylation of an Aurora B substrate at the kinetochore depends on its distance from the kinase at the inner centromere and that it is this distance that is affected by tension.

D. Liu, G. Vader, M. J. M. Vromans, M. A. Lampson, S. M. A. Lens, Sensing chromosome bi-orientation by spatial separation of Aurora B kinase from kinetochore substrates. Science 323, 1350–1353 (2009). [Abstract] [Full Text]