Professor Iain Hagan

Execution and control of cell division in fission yeast

Errors in chromosome transmission can make a major contribution to the transformation from a normal growth state into a cancerous one. The loss of a chromosome alters the balance of tumour suppressor and tumour promoter genes. In turn this selects for subsequent changes in the ensuing cell divisions that lead to tumourigenesis. Chromosome separation into two daughter chromatids is achieved by a specialised structure called the mitotic spindle. Before committing to division the cell must ensure that the conditions are right. Notonly must the cell have gained sufficient mass to justify division but the genome must be intact and any damage that has occurred since DNA replication must have been repaired. During mitosis a complex regulatory network ensures that chromatid separation does not happen until all of the chromosomes are attached to both spindle poles. These decision and monitoring networks are essentially the same in all eukaryotes from yeast to man. It is therefore possible to study the complexities of cell division in the relatively simple unicellular yeasts and gain insight into the control of celldivision in man. The yeasts are particularly suited to this as they are very cheap to propogate, have a short generation time, can grow in synthetic media and have excellent genetics.