>> Mar 10 - Seminar Masanori Mishima (Gurdon Institute) 14:00 TM1 T0.08

Clustering of the centralspindlin Kinesin-6/RhoGAP complex regulated by Aurora B and 14-3-3 is essential for its sharp midzone accumulation during cytokinesis.

Cytokinesis in animal cells requires post-metaphase microtubule bundle structures such as the central spindle and midbody. Centralspindlin, a heterotetrameric complex consisting of Kinesin-6 (MKLP1/Pavarotti/ZEN-4) and RhoGAP (MgcRacGAP/RacGAP50C/CYK-4) subunits, is essential for the formation of these structures. Centralspindlin also plays a critical role in recruitment of various cytokinesis regulators to the site of division. However, the mechanism of sudden accumulation of centralspindlin to the centre of interpolar microtubule bundles has been unclear. We have discovered that higher-order clustering of centralspindlin is critical for its processive motility in vitro and for midbody formation in vivo. Furthermore, we have found that the clustering is coordinately regulated by Aurora B kinase and 14-3-3 protein. Based on these findings, we propose a positive feedback loop of centralspindlin clustering and microtubule organisation that may underlie its distinctive localisation during cytokinesis.