Bod1, a novel kinetochore protein required for chromosome biorientation

Abstract

We have combined the proteomic analysis of Xenopus laevis in vitro–assembled chromosomes with RNA interference and live cell imaging in HeLa cells to identify novel factors required for proper chromosome segregation. The first of these is Bod1, a protein conserved throughout metazoans that associates with a large macromolecular complex and localizes with kinetochores and spindle poles during mitosis. Small interfering RNA depletion of Bod1 in HeLa cells produces elongated mitotic spindles with severe biorientation defects. Bod1-depleted cells form syntelic attachments that can oscillate and generate enough force to separate sister kinetochores, suggesting that microtubule–kinetochore interactions were intact. Releasing Bod1-depleted cells from a monastrol block increases the frequency of syntelic attachments and the number of cells displaying biorientation defects. Bod1 depletion does not affect the activity or localization of Aurora B but does cause mislocalization of the microtubule depolymerase mitotic centromere- associated kinesin and prevents its efficient phosphorylation by Aurora B. Therefore, Bod1 is a novel kinetochore protein that is required for the detection or resolution of syntelic attachments in mitotic spindles.

Quantitative Dissection and Stoichiometry Determination of the Human SET1/MLL Histone Methyltransferase Complexes

“…Bod1 and Bod1L1 are human paralogs of yShg1p and exclusive to SET1B. The bi-orientation defected 1 protein (Bod1) is important for proper chromosome segregation during mitosis (54). Bod1 and the highly similar Bod1L1 were identified in our experiments as interacting with all members of the WRAD complex (Fig.…”

“…Bod1 was linked previously to chromosome segregation during mitosis (54). The phenotype of Bod1 depletion and the association of the other SET1B complex member, Wdr82, with PP1, whose inactivation leads to a mitotic arrest (62), hints at a link between the SET1B complex, histone methylation, and mitotic progression.…”

Aneuploidy in mitosis of PtK1 cells is generated by random loss and nondisjunction of individual chromosomes

“…Anaphase onset in the presence of syntelic attachments would produce chromosome ND, because both sister kinetochores are connected to the same pole. However, several lines of evidence converge to demonstrate that syntelic attachments activate the mitotic checkpoint (Pinsky and Biggins, 2005;Porter et al, 2007), rendering it less likely that syntelic chromosomes will undergo ND in checkpoint-proficient cells. In our data, the high ND frequencies obtained after inducing large amounts of merotelic orientations (NOC treatment) (Fig.…”

Bi-orienting chromosomes: acrobatics on the mitotic spindle

“…How can this be reconciled? One possibility is that functional counterparts of the Dam1 complex exist in metazoa, albeit with little homology in amino acid sequences; Ska1/2, Cep57, and Bod1 are such candidates (Hanisch et al 2006;Emanuele and Stukenberg 2007;Porter and Swedlow 2007), although their functional similarity to the Dam1 complex must be studied further. Alternatively, the role of the Dam1 complex may be more important in organisms such as budding yeast, in which a single kinetochore attaches to a single microtubule in metaphase (Winey et al 1995).…”