Role of the mitotic kinase Aurora A in spindle assembly and chromosome segregation
The Xenopus protein Maskin, previously identified and characterized in the context of its role in translational control during oocyte maturation, belongs to the TACC protein family. In other systems, members of this family have been shown to localize to centrosomes during mitosis and play a role in microtubule stabilization. We have examined the putative role of Maskin in spindle assembly and centrosome aster formation in the Xenopus egg extract system. We found that Maskin plays an essential role for microtubule assembly during M-phase and that both its localization and function are regulated by phosphorylation by the Xenopus Aurora A kinase. We also obtained some evidence indicating that Maskin works in concert with XMAP215 to oppose the destabilizing activity of XKCM1, therefore promoting microtubule growth from the centrosome.
(Peset I, Seiler J, Sardon T, Bejarano LA, Rybina S, Vernos I. J. Cell Biol.26;170(7):1057-66, 2005).
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Maskin localization in XL177 cells. Maskin localizes to the centrosome of some interphase cells. During mitosis it becomes strongly enriched at the centrosome and localizes faintly on some spindle microtubules. In the overlay, microtubules are green, Maskin is red and DNA is blue. Scale bar, 20ƒÝm except in interphase and telophase cells 10ƒÝm. |