Phosphorylation of survivin at threonine 34 inhibits its mitotic function and enhances its cytoprotective activity

Abstract

Survivin is an essential chromosomal passenger protein required for mitotic progression. It is also an inhibitor of apoptosis and can prevent caspase-mediated cell death. In addition, survivin levels are elevated in cancer cells where its presence correlates with increased resistance to chemo- and radio-therapy, which makes it an attractive target for novel anti-cancer strategies. Interestingly, survivin is phosphorylated by the mitotic kinase, cdk1, and a non-phosphorylatable form, survivinT34A, cannot inhibit apoptosis. Here we rigorously test the ability of survivin wT34A and its corresponding phosphomimetic, survivinT34E, to promote cell viability through survivin's dual roles. The effects of these mutations are diametrically opposed: survivinT34A accelerates cell proliferation and promotes apoptosis, whereas survivinT34E retards growth and promotes survival. Thus the phosphorylation status of survivin at T34 is pivotal to a cell's decision to live or die. ©2009 Landes Bioscience.