14-3-3 epsilon inhibits premature centriole disengagement by inhibiting the activity of Plk1 and Separase.

Abstract

The 14-3-3 protein family regulates several pathways in mammalian cells, including centrosome duplication. However, the precise mechanisms by which 14-3-3 paralogs regulate the centrosome cycle remain unclear. To identify the mechanisms by which 14-3-3{varepsilon} regulates centrosome duplication, we altered two conserved acidic residues in the 14-3-3{varepsilon} phospho-peptide-binding pocket that regulate complex formation and dissociation with the associated ligands, D127 and E134, to Alanine. Altering these residues to Alanine led to opposing effects on centrosome duplication; the D127A mutant inhibited centrosome duplication, while cells expressing the E134A mutant showed the presence of supernumerary centrosomes. We demonstrate that 14-3-3{varepsilon} does not inhibit centriole duplication, as reported for 14-3-3{gamma}, but inhibits centriole disengagement. Using a combination of pharmacological and genetic approaches, we demonstrate that 14-3-3{varepsilon} inhibits the activity of Plk1 and Separase, leading to disengagement defects that ultimately lead to decreased proliferation and cell death. Our work demonstrates that different 14-3-3 paralogs regulate different steps in the centrosome cycle, and disrupting complex formation between 14-3-3{varepsilon} and Plk1 or Separase could be a novel therapeutic strategy in tumor cells.