Supplying a Start-Up

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Science  23 Feb 2007:
Vol. 315, Issue 5815, pp. 1054
DOI: 10.1126/science.315.5815.1054b

After an injury to its axon, a neuron must reorganize rapidly in order to establish a new growth cone at the tip of the transected segment. The growth cone can then search for and reestablish synaptic contacts, but the axon must supply the requisite materials to promote regrowth.

By imaging cultured Aplysia neurons after axotomy, Erez et al. have followed the events by which axons establish new growth cones. Soon after an axon has been cut, the end of the portion still attached to the cell body partitions into two compartments. In the proximal region, vesicles can be observed en route to the plasma membrane from the Golgi complex; if the production of Golgi-derived vesicles is blocked, a new growth cone cannot be established. In the distal region, vesicles also accumulate, but these arise via the retrieval of membrane from the cell surface. What drives this traffic are the microtubules, which form the structural scaffold of the axon and rearrange to establish a region that segregates the two classes of vesicles. This process, which involves the reorientation of polarized microtubules, collects and concentrates the components needed to regenerate a motile growth cone. — SMH

J. Cell Biol. 176, 497 (2007).

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