Regulation of Wee1 kinase in response to protein synthesis inhibition.

To investigate the mechanism coupling growth (protein synthesis) with cell division, we examined the relationship between the tyrosine kinase Wee1 that inhibits Cdc2-Cdc13 mitosis-inducing kinase by phosphorylating it, and protein synthesis inhibition in fission yeast. The wee1-50 mutant showed supersensitivity to protein synthesis inhibitor, cycloheximide. Wee1 was essential for the G(2) delay upon a partial inhibition of protein synthesis. Indeed, the protein synthesis inhibition caused an increase in the Wee1 protein by the Sty1/Spc1 MAPK-dependent transcriptional and the Sty1/Spc1 MAPK-independent post-transcriptional regulations. Further, the results indicated that the post-transcriptional regulation is important for the G(2) delay.