Linking centrosomes and actin

Centrosomal changes during cell division are relayed to the actin cytoskeleton by the centrosomal protein CP190, report Sasidhar Chodagam, Jordan Raff (Gurdon Institute, Cambridge, UK), and colleagues.Although CP190 binds to microtubules and was the first centrosomal protein identified in flies, researchers have not detected a microtubule or centrosomal defect in fly CP190 mutants. The catch to those experiments, however, was that maternal stores of CP190 were available to the mutant embryos during early development.

The team therefore generated mutant embryos that lack even the maternal supply. These embryos' centrosomes seemed normal, but the dividing nuclei failed to disperse evenly in the embryo and instead remained crowded at the anterior end.

This nuclear spreading is known to depend on the contraction of cortical actin, which occurs in pulses between rapid cycles of mitosis in the...