Centrosome (arrow) moves before nucleus.

HATTEN/MACMILLAN

Centrosome and nucleus engage in an inchworm-like dance in certain migrating neurons, according to David Solecki, Mary Hatten, and colleagues (Rockefeller University, New York, NY).

The neurons under study migrate along glia to form the layered architecture of higher brain areas. Whereas primitive brain areas have a nuclear organization, the cortex builds its more complex circuitry by sending its neurons off on these treks.

The neurons were known to move and adhere in a periodic cycle, with a long process leading the way and the nucleus at the rear. But the Rockefeller group now shows that the centrosome moves forward first; the nucleus then closes the gap. This cycle has a similar period to the adhesion cycle. Although the relative timing of the events is not known, coordination may rely on mPar6α, which the Rockefeller group identifies as a centrosome component essential for centrosome and cell movement.

The nucleus is surrounded by a perinuclear microtubule cage whose shape is distorted during the cycle. The cage and nucleus are probably moved towards the centrosome by dynein. The movement of the centrosome itself is more of a mystery, both in terms of the responsible motor and the structure against which the motor pulls.

Reference:

Solecki, D.J., et al. 2004. Nat. Neurosci. doi:.