How do cells control chromosome segregation? We wish to understand how cells ensure that an each daughter cell receives an equal and identical copy of the genome when when they divide. We know that there is a checkpoint in the cell that detects when a chromosome has not attached correctly to the mitotic spindle and that even one out of 46 chromosomes will delay cells in mitosis. This means that the checkpoint must be very potent. Remarkably, however, once the last chromosome attaches, the checkpoint rapidly switches off, meaning it must be both potent and responsive. We now know many of the components of the checkpoint and the protein complexes they form; our problem now is to determine the kinetics of complex assembly and disassembly, and constructing a model to account for the properties of the checkpoint. We are approaching this by using knock-in cell lines in which we tag the endogenous protein with GFP or RFP, and measuring protein dynamics by fluorescence correlation spectroscopy and epifluorescence microscopy.
- Collin, P., Nashchekina, O., Walker, R. and Pines, J. (2013) ‘The Spindle Assembly Checkpoint works like a rheostat not a toggle-switch’ Nat. Cell Biol. doi:10.1038/ncb2855
- Izawa, D. and Pines, J. (2012) ‘Mad2 and the APC/C compete for the same site on Cdc20 to ensure proper chromosome segregation’. J. Cell Biol. 199, 27-37.
- Mansfeld, J., Collin, P., Collins, M.O., Choudhary, J. and Pines, J. (2011) ‘APC15 drives the turnover of MCC-Cdc20 to make the Spindle Assembly Checkpoint responsive to kinetochore attachment’ Nat. Cell Biol. 13, 1234-1244.