Chromosomal enrichment and activation of the aurora B pathway are coupled to spatially regulate spindle assembly.

Chromatin-induced spindle assembly depends on regulation of microtubule-depolymerizing proteins by the chromosomal passenger complex (CPC), consisting of Incenp, Survivin, Dasra (Borealin), and the kinase Aurora B, but the mechanism and significance of the spatial regulation of Aurora B activity remain unclear. Here, we show that the Aurora B pathway is ...
suppressed in the cytoplasm of Xenopus egg extract by phosphatases, but that it becomes activated by chromatin via a Ran-independent mechanism. While spindle microtubule assembly normally requires Dasra-dependent chromatin binding of the CPC, this function of Dasra can be bypassed by clustering Aurora B-Incenp by using anti-Incenp antibodies, which stimulate autoactivation among bound complexes. However, such chromatin-independent Aurora B pathway activation promotes centrosomal microtubule assembly and produces aberrant achromosomal spindle-like structures. We propose that chromosomal enrichment of the CPC results in local kinase autoactivation, a mechanism that contributes to the spatial regulation of spindle assembly and possibly to other mitotic processes.
Mesh Terms:
Animals, Antibodies, Cell Extracts, Centrosome, Chromosomal Proteins, Non-Histone, Chromosomes, Enzyme Activation, Histones, Microtubules, Mitotic Spindle Apparatus, Ovum, Phosphorylation, Protein Binding, Protein-Serine-Threonine Kinases, Stathmin, Xenopus, Xenopus Proteins, ran GTP-Binding Protein
Dev. Cell
Date: Jan. 01, 2007
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