Mps1 phosphorylates Borealin to control Aurora B activity and chromosome alignment.

Research paper by Nannette N Jelluma, Arjan B AB Brenkman, Niels J F NJ van den Broek, Carin W A CW Cruijsen, Maria H J MH van Osch, Susanne M A SM Lens, René H RH Medema, Geert J P L GJ Kops

Indexed on: 05 Feb '08Published on: 05 Feb '08Published in: Cell


Maintenance of chromosomal stability relies on coordination between various processes that are critical for proper chromosome segregation in mitosis. Here we show that monopolar spindle 1 (Mps1) kinase, which is essential for the mitotic checkpoint, also controls correction of improper chromosome attachments. We report that Borealin/DasraB, a member of the complex that regulates the Aurora B kinase, is directly phosphorylated by Mps1 on residues that are crucial for Aurora B activity and chromosome alignment. As a result, cells lacking Mps1 kinase activity fail to efficiently align chromosomes due to impaired Aurora B function at centromeres, leaving improper attachments uncorrected. Strikingly, Borealin/DasraB bearing phosphomimetic mutations restores Aurora B activity and alignment in Mps1-depleted cells. Mps1 thus coordinates attachment error correction and checkpoint signaling, two crucial responses to unproductive chromosome attachments.