title: RZZ and Mad1 dynamics in Drosophila mitosis.
abstract: The presence or absence of Mad1 at kinetochores is a major determinant of spindle assembly checkpoint (SAC) activity, the surveillance mechanism that delays anaphase onset if one or more kinetochores remain unattached to spindle fibers. Among the factors regulating the levels of Mad1 at kinetochores is the Rod, Zw10, and Zwilch (RZZ) complex, which is required for Mad1 recruitment through a mechanism that remains unknown. The relative dynamics and interactions of Mad1 and RZZ at kinetochores have not been extensively investigated, although Mad1 has been reported to be stably recruited to unattached kinetochores. In this study, we directly compare Mad1-green fluorescent protein (GFP) turnover dynamics on unattached Drosophila kinetochores with that of RZZ, tagged either with GFP-Rod or GFP-Zw10. We find that nearly 40 % of kinetochore-bound Mad1 has a significant dynamic component, turning over with a half-life of 12 s. RZZ in contrast is essentially stable on unattached kinetochores. In addition, we report that a fraction of RZZ and Mad1 can co-immunoprecipitate, indicating that the genetically determined recruitment hierarchy (in which Mad1 depends on RZZ) may reflect a physical association of the two complexes.
authors.affiliation: Sorbonne Paris Cité, Université Paris Diderot, Paris, France.
authors.forename: Lénaïg
authors.initials: L
authors.lastname: Défachelles
authors.forename: Natacha
authors.initials: N
authors.lastname: Raich
authors.forename: Régine
authors.initials: R
authors.lastname: Terracol
authors.forename: Xavier
authors.initials: X
authors.lastname: Baudin
authors.forename: Byron
authors.initials: B
authors.lastname: Williams
authors.forename: Michael
authors.initials: M
authors.lastname: Goldberg
authors.forename: Roger E
authors.initials: RE
authors.lastname: Karess
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D015870:Gene Expression; D023061:Gene Order; D017930:Genes, Reporter; D056426:Genetic Loci; D018386:Kinetochores / Q000378:metabolism*; D059566:M Phase Cell Cycle Checkpoints; D011485:Protein Binding; D021381:Protein Transport; D008941:Spindle Apparatus / Q000378:metabolism; D019076:Transgenes
chemical_list: D029721:Drosophila Proteins