The role of DSC1 components cdc10+, rep1+ and rep2+ in MCB gene transcription at the mitotic G1-S boundary in fission yeast

In this paper, we describe the transcription profile of a group of genes at the G1-S boundary of fission yeast in synchronously dividing mitotic cells, under a variety of different conditions. This transcription profile is unaffected in cells where either cdc10(+) or cdc10-C4 are constitutively overexpressed. In contrast, overexpression of either rep1(+) or rep2(+) results in constitutive expression of MCB-regulated genes, suggesting that these polypeptides have important regulatory properties in controlling MCB transcription. Finally, we examine the pattern of MCB-regulated transcription in cells where the G1 period is extended. Surprisingly, we find that the wee1-50 mutation causes MCB transcription throughout the cell cycle, whereas cells re-fed after nitrogen starvation have normal expression patterns. The implications of these observations for understanding MCB-regulated transcription are discussed.