January 9, 2012

As a reader of this blog, I bet you are simply dazzled by mitosis like I am. Or, you may be sick of mitosis and my love of mitosis images. If that’s case, then scram! Mitosis is one of the most photogenic events in a cell and today’s images support this widely-accepted claim.

During mitosis, a lot has to happen correctly for two daughter cells to have an equal number of chromosomes. The list of participating proteins is as long as my arm, and includes several kinases that regulate mitotic progression. Aurora B kinase participates in just about every major mitotic event—it regulates chromosome condensation, localizes to microtubules, functions in monitoring and ensuring chromosome attachment to the spindle, and is necessary for cytokinesis. The role of a similar kinase, Aurora A, is less clear, possibly due to differences in the techniques used in previous research that led to ambiguous or contradictory results. Hégarat and colleagues recently used a chemical genetic strategy to find that Aurora A kinase is important in chromosome alignment and segregation. In addition, Aurora A and Aurora B kinases cooperate together to coordinate chromosome segregation and microtubule dynamics. Images above show different mitotic cells after Aurora A kinase depletion (chromosomes are blue, spindle is green, spindle poles are red). Many of the cells appear normal, and may represent different stages of mitosis. Some cells displayed gross defects in spindle morphology, as seen as the presence of multipolar and monopolar spindles (bottom right two images).

Hegarat, N., Smith, E., Nayak, G., Takeda, S., Eyers, P., & Hochegger, H. (2011). Aurora A and Aurora B jointly coordinate chromosome segregation and anaphase microtubule dynamics originally published in The Journal of Cell Biology, 195 (7), 1103-1113 DOI: 10.1083/jcb.201105058