A checkpoint-independent mechanism delays entry into mitosis after UV irradiation

Abstract

When cells are exposed to stress they delay entry into mitosis. The most extensively studied mechanism behind this delay is the DNA-damage-induced G2/M checkpoint. Here, we show the existence of an additional stress-response pathway which is independent of the classic ATR/Rad3-dependent checkpoint. This novel mechanism delays entry mitosis independent of the spindle assembly checkpoint and the mitotic kinases Fin1, Ark1 and Plo1. The pathway delays activation of the mitotic CDK, Cdc2, after UV irradiation. Furthermore, we demonstrate that translation of the mitotic cyclin Cdc13 is selectively downregulated after UV-irradiation and we propose that this downregulation of Cdc13 contributes to the delayed activation of Cdc2 and the delayed mitosis.