title: All together now: Polo joins the kinase network controlling the spindle assembly checkpoint in Drosophila.
abstract: Maintenance of genomic stability during eukaryotic cell division relies on the Spindle Assembly Checkpoint (SAC), which has evolved as a surveillance mechanism that monitors kinetochore-microtubule attachment and prevents APC/C-mediated mitotic exit until all chromosomes are properly attached to the mitotic spindle. Reversible protein phosphorylation has long been accredited as a regulatory mechanism of the SAC. Nevertheless, knowledge of how several mitotic kinases act in concert within the signaling pathway to orchestrate SAC function is still emerging. In a recent study, we undertook a comprehensive dissection of the hierarchical framework controlling SAC function in Drosophila cells. We found that Polo lies at the top of the SAC pathway promoting the efficient recruitment of Mps1 to unattached kinetochores. This renders Mps1 fully active to control BubR1 phosphorylation that generates the 3F3/2 phosphoepitope at tensionless kinetochores. We have proposed that Polo is required for SAC function and that the molecular outcome of Mps1-dependent 3F3/2 formation is to promote the association of Cdc20 with BubR1 allowing proper kinetochore recruitment of Cdc20 and efficient assembly of the Mitotic Checkpoint Complex (MCC) required for a sustained SAC response.
authors.affiliation: IBMC; Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto, Portugal.
authors.forename: Carlos
authors.initials: C
authors.lastname: Conde
authors.affiliation: IBMC; Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto, Portugal.
authors.forename: Mariana
authors.initials: M
authors.lastname: Osswald
authors.affiliation: IBMC; Instituto de Biologia Molecular e Celular; Universidade do Porto; Porto, Portugal; ICBAS; Department of Molecular Biology; Instituto de Ciências Biomédicas Abel Salazar; Universidade do Porto; Porto, Portugal.
authors.forename: Claudio E
authors.initials: CE
authors.lastname: Sunkel
mesh_terms: D000818:Animals; D004330:Drosophila / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D059566:M Phase Cell Cycle Checkpoints; D008954:Models, Biological; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D029721:Drosophila Proteins; C072004:polo protein, Drosophila; D017346:Protein Serine-Threonine Kinases
keywords: Aurora B; BubR1; Cdc20; Mps1; Polo; mitosis; phosphoregulation; spindle assembly checkpoint