title: Mitotic chromatin regulates phosphorylation of Stathmin/Op18.
abstract: Meiotic and mitotic spindles are required for the even segregation of duplicated chromosomes to the two daughter cells. The mechanism of spindle assembly is not fully understood, but two have been proposed that are not mutually exclusive. The 'search and capture' model suggests that dynamic microtubules become progressively captured and stabilized by the kinetochores on chromosomes, leading to spindle assembly. The 'local stabilization' model proposes that chromosomes change the state of the cytoplasm around them, making it more favourable to microtubule polymerization. It has been shown that Stathmin/Op18 inhibits microtubule polymerization in vitro by interaction with tubulin, and that overexpression in tissue culture cells of non-phosphorylatable mutants of Stathmin/Op18 prevents the assembly of mitotic spindles. We have used Xenopus egg extracts and magnetic chromatin beads to show that mitotic chromatin induces phosphorylation of Stathmin/Op18. We have also shown that Stathmin/Op18 is one of the factors regulated by mitotic chromatin that governs preferential microtubule growth around chromosomes during spindle assembly.
authors.affiliation: EMBL, Cell Biology Programme, Heidelberg, Germany. andersen@emblheidelberg.de
authors.forename: S S
authors.initials: SS
authors.lastname: Andersen
authors.forename: A J
authors.initials: AJ
authors.lastname: Ashford
authors.forename: R
authors.initials: R
authors.lastname: Tournebize
authors.forename: O
authors.initials: O
authors.lastname: Gavet
authors.forename: A
authors.initials: A
authors.lastname: Sobel
authors.forename: A A
authors.initials: AA
authors.lastname: Hyman
authors.forename: E
authors.initials: E
authors.lastname: Karsenti
mesh_terms: D000818:Animals; D001665:Binding Sites; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002843:Chromatin / Q000502:physiology*; D003001:Cloning, Molecular; D008868:Microtubule Proteins; D008938:Mitosis; D016297:Mutagenesis, Site-Directed; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D008941:Spindle Apparatus / Q000378:metabolism; D050777:Stathmin; D014981:Xenopus; D029867:Xenopus Proteins
chemical_list: D002843:Chromatin; D008868:Microtubule Proteins; D010750:Phosphoproteins; C493996:STMN1 protein, Xenopus; D050777:Stathmin; D029867:Xenopus Proteins; D016203:CDC2 Protein Kinase; D010749:Phosphoprotein Phosphatases