title: PI 3-kinase-dependent phosphorylation of Plk1-Ser99 promotes association with 14-3-3γ and is required for metaphase-anaphase transition.
abstract: Polo-like kinase 1 (Plk1) controls multiple aspects of mitosis and is activated through its phosphorylation at Thr210. Here we identify Ser99 on Plk1 as a novel mitosis-specific phosphorylation site, which operates independently of Plk1-Thr210 phosphorylation. Plk1-Ser99 phosphorylation creates a docking site for 14-3-3γ, and this interaction stimulates the catalytic activity of Plk1. Knockdown of 14-3-3γ or replacement of wild-type (WT) Plk1 by a Ser99-phospho-blocking mutant leads to a prometaphase/metaphase-like arrest due to the activation of the spindle assembly checkpoint. Inhibition of phosphatidylinositol 3-kinase (PI3K) and Akt significantly reduces the level of Plk1-Ser99 phosphorylation and delays metaphase to anaphase transition. Plk1-Ser99 phosphorylation requires not only Akt activity but also protein(s) associated with Plk1 in a mitosis-specific manner. Therefore, mitotic Plk1 activity is regulated not only by Plk1-Thr210 phosphorylation, but also by Plk1 binding to 14-3-3γ following Plk1-Ser99 phosphorylation downstream of the PI3K-Akt signalling pathway. This novel Plk1 activation pathway controls proper progression from metaphase to anaphase.
authors.affiliation: Division of Biochemistry, Aichi Cancer Center Research Institute, Nagoya, Aichi 464-8681, Japan.
authors.forename: Kousuke
authors.initials: K
authors.lastname: Kasahara
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Goto
authors.forename: Ichiro
authors.initials: I
authors.lastname: Izawa
authors.forename: Tohru
authors.initials: T
authors.lastname: Kiyono
authors.forename: Nobumoto
authors.initials: N
authors.lastname: Watanabe
authors.forename: Sabine
authors.initials: S
authors.lastname: Elowe
authors.forename: Erich A
authors.initials: EA
authors.lastname: Nigg
authors.forename: Masaki
authors.initials: M
authors.lastname: Inagaki
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D000705:Anaphase; D000818:Animals; D055162:Biocatalysis; D017173:Caenorhabditis elegans; D018797:Cell Cycle Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D059566:M Phase Cell Cycle Checkpoints; D008677:Metaphase; D008954:Models, Biological; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction; D000097869:Polo-Like Kinase 1
chemical_list: D048948:14-3-3 Proteins; D018797:Cell Cycle Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010768:Phosphoserine; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D000097869:Polo-Like Kinase 1