...

Identifying the molecular mechanisms of mitotic checkpoint regulation by Mps1.

...

One of the first components of the spindle assembly checkpoint identified by a genetic screen in budding yeast was dubbed Mps1 (monopolar spindle 1). Kinase activity of Mps1 increases at the G1/S transition without a corresponding increase in protein levels. Mps1 activity then peaks at the G2/M transition and drops sharply in early G1. Phosphorylation of Mps1 is enhanced upon activation of the spindle checkpoint with nocodazole resulting in a ~30-fold increase in Mps1 activity. We have recently identified the autophosphorylation of T676 in the activation loop of Mps1 and showed that it is essential for Mps1 function. Using specific inhibitors we set out to investigate the contribution of Mps1 kinase activity to mitotic progression in human cells. We have also shown that depletion of Mps1 by siRNA prevented cells from accumulating in mitosis upon treatment with the spindle poison nocodazole, confirming a role for Mps1 in mitotic checkpoint activation. To prove that kinase activity of Mps1 is indispensable for the mitotic checkpoint in human cells we will investigate the localisation and the activity of the essential mitotic checkpoint proteins at unattached kinetochores of cells lacking Mps1 activity and their restoration by expression of wild-type Mps1.

Other projects