title: Plk phosphorylation regulates the microtubule-stabilizing protein TCTP.
abstract: The mitotic polo-like kinases have been implicated in the formation and function of bipolar spindles on the basis of their respective localizations and mutant phenotypes. To date, this putative regulation has been limited to a kinesin-like motor protein, a centrosomal structural protein, and two microtubule-associated proteins (MAPs). In this study, another spindle-regulating protein, the mammalian non-MAP microtubule-binding and -stabilizing protein, the translationally controlled tumor protein (TCTP), was identified as a putative Plk-interacting clone by a two-hybrid screen. Plk phosphorylates TCTP on two serine residues in vitro and cofractionates with the majority of kinase activity toward TCTP in mitotic cell lysates. In addition, these sites were demonstrated to be phosphorylated in vivo. Overexpression of a Plk phosphorylation site-deficient mutant of TCTP induced a dramatic increase in the number of multinucleate cells, rounded cells with condensed ball-like nuclei, and cells undergoing cell death, similar to both the reported anti-Plk antibody microinjection and the low-concentration taxol treatment phenotypes. These results suggest that phosphorylation decreases the microtubule-stabilizing activity of TCTP and promotes the increase in microtubule dynamics that occurs after metaphase.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA. fred_yarm@dfci.harvard.edu
authors.forename: Frederic R
authors.initials: FR
authors.lastname: Yarm
mesh_terms: D020816:Amino Acid Motifs; D000705:Anaphase; D000818:Animals; D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D018797:Cell Cycle Proteins; D002455:Cell Division; D002460:Cell Line / Q000166:cytology / Q000378:metabolism; D016368:Frameshift Mutation; D006367:HeLa Cells / Q000166:cytology / Q000378:metabolism; D006801:Humans; D007668:Kidney; D008677:Metaphase; D051379:Mice; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D017239:Paclitaxel / Q000494:pharmacology; D010766:Phosphorylation; D010768:Phosphoserine / Q000737:chemistry; D017354:Point Mutation; D025941:Protein Interaction Mapping; D011494:Protein Kinases / Q000502:physiology*; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000502:physiology; D017384:Sequence Deletion; D008941:Spindle Apparatus / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D013329:Structure-Activity Relationship; D014162:Transfection; D000090324:Tumor Protein, Translationally-Controlled 1; D020798:Two-Hybrid System Techniques; D000097869:Polo-Like Kinase 1
chemical_list: D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D017239:Paclitaxel; D010768:Phosphoserine; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D000090324:Tumor Protein, Translationally-Controlled 1; D000097869:Polo-Like Kinase 1; C000715647:TPT1 protein, human; C000715648:Tpt1 protein, mouse