Student Theses and Dissertations

Date of Award

2006

Document Type

Thesis

RU Laboratory

Funabiki Laboratory

Keywords

chromosome segregation, chromosomal passenger complex, CPC activation, Aurora B, spindle assembly

Abstract

Chromosome segregation during cell division requires spindle assembly around M-phase chromatin. In cells lacking centrosomes, such as those found in female meiosis, chromosomes themselves nucleate and stabilize microtubules in order to promote accurate spindle formation. Here we present a description of the composition and function of the vertebrate chromosomal passenger complex (CPC), known to include Incenp, Survivin, and the kinase Aurora B. We report the identification of Dasra A and Dasra B as two new components of the vertebrate CPC, and demonstrate that the CPC is required for chromatin-dependent spindle formation in Xenopus egg extracts. The failure of microtubule stabilization caused by depletion of the chromosomal passenger complex is rescued by codepletion of the microtubule-depolymerizing kinesin MCAK, whose activity is negatively regulated by Aurora B. We demonstrate that the Aurora B pathway is normally suppressed in the cytosol, but becomes activated by chromatin and centrosomes, leading to the phosphorylation of both histone H3 and the microtubule destabilizing protein Op18/Stathmin. Chromatin-mediated CPC activation and spindle assembly require Dasra protein-dependent chromatin binding by the CPC, but this function of Dasra proteins can be bypassed by adding anti-Incenp antibodies, which autonomously stimulate Aurora B pathway activity. Such inappropriate CPC activation leads to the formation of centrosomal spindles lacking chromosomes. These results demonstrate that Dasra proteins make the Aurora B pathway competent for chromatindependent activation, and provide a mechanism for the spatial regulation of spindle assembly.

Comments

A thesis presented to the faculty of The Rockefeller University in partial fulfillment of the requirements for the degree of Doctor of Philosophy.

Permanent URL

http://hdl.handle.net/10209/234

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