Although Skp2 has been thought to mediate the degradation of p27 at the G1-S transition, Skp2 -/- cells exhibit accumulation of p27 in S-G2 phase with overreplication. We demonstrate that Skp2 -/- p27 -/- mice do not exhibit the overreplication phenotype, suggesting that p27 accumulation is required for its development. Hepatocytes of Skp2 -/- mice entered the endoduplication cycle after mitogenic stimulation, whereas this phenotype was not apparent in Skp2 -/- p27 -/- mice. Cdc2-associated kinase activity was lower in Skp2 -/- cells than in wild-type cells, and a reduction in Cdc2 activity was sufficient to induce overreplication. The lack of p27 degradation in G2 phase in Skp2 -/- cells may thus result in suppression of Cdc2 activity and consequent inhibition of entry into M phase. These data suggest that p27 proteolysis is necessary for the activation of not only Cdk2 but also Cdc2, and that Skp2 contributes to regulation of G2-M progression by mediating the degradation of p27. © 2004 Cell Press.
Nakayama, K., Nagahama, H., Minamishima, Y. A., Miyake, S., Ishida, N., Hatakeyama, S., … Nakayama, K. I. (2004). Skp2-Mediated degradation of p27 regulates progression into mitosis. Developmental Cell, 6(5), 661–672. https://doi.org/10.1016/S1534-5807(04)00131-5