14-3-3 Binding regulates catalytic activity of human Wee1 kinase

The mitotic inducer Cdc2 is negatively regulated, in part, by phosphorylation on tyrosine 15. Human Wee1 is a tyrosine-specific protein kinase that phosphorylates Cdc2 on tyrosine 15. Human Wee1 is subject to multiple levels of regulation including reversible phosphorylation, proteolysis, and protein-protein interactions. Here we have investigated the contributions made by 14-3-3 binding to human Wee1 regulation and function. We report that the interactions of 14-3-3 proteins with human Wee1 are reduced during mitosis and are stable in the presence of the protein kinase inhibitor UCN-01. A mutant of Wee1 that is incapable of binding to 14-3-3 proteins has lower enzymatic activity, and this likely accounts for its reduced potency relative to wild-type Wee1 in inducing a G₂ cell cycle delay when overproduced in vivo. These findings indicate that 14-3-3 proteins function as positive regulators of the human Wee1 protein kinase.