In vivo localisation of fission yeast cyclin-dependent kinase cdc2p and cyclin B cdc13p during mitosis and meiosis

We investigated the in vivo localisation of fission yeast cyclin-dependent kinase cdc2p during mitosis and meiosis. Fusion to yellow fluorescent prote in (YFP) revealed that cdc2-YFP is present in the cytoplasm at all stages o f the cell cycle. Nuclear cdc2-YFP fluorescence oscillates with that of cdc 13-YFP cyclin. At G(1)/S, at least one of cdc13p, cig1p or cig2p B-type cyc lins is required for the accumulation of cdc2-YFP into the nucleus. Cdc2-YF P and cdc13-YFP are highly enriched on the spindle pole body of cells in la te G(2) or arrested at S phase. Both accumulate on the spindle pole bodies and the spindle in prophase and metaphase independently of the microtubule- associated protein dis1p. In anaphase, the cdc2p/cdc13p complex leaves the spindle prior to sister chromatid separation, and cdc13-YFP is enriched at the nuclear periphery before fluorescence disappears. If cdc13p cannot be r ecognized by the anaphase-promoting complex, cdc2-YFP and cdc13-YFP remain associated with the spindle. In mating cells, cdc2-YFP enters the nucleus a s soon as the cells undergo fusion. During karyogamy and meiotic prophase, cdc2-YFP is highly enriched on the centromeres. In meiosis I, association o f cdc2-YFP with the spindle and the spindle pole bodies shows differences t o mitotic cells, suggesting different mechanisms of spindle formation. This study suggests that changes in cdc2p localisation are important for both m itosis and meiosis regulation.