Setting the Right Course

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Science  09 Mar 2012:
Vol. 335, Issue 6073, pp. 1148
DOI: 10.1126/science.335.6073.1148-c
CREDIT: GÄRTNER ET AL., EMBO J. 10.1038/EMBOJ.2012.41 (2012)

Neurons are remarkably asymmetric, with a cell body surrounded by dendrites and a single axon. Such asymmetry requires that the orientation of the neuronal growth axis be defined early in the development of the neuron. Gärtner et al. looked at mouse hippocampal embryonic neurons in the first stages of polarization in vitro to determine how this process occurs. They found that the first neurite formed even before the orientation of the Golgi and centrosome, previously believed to be the key orchestrators of polarity. Initiation of the first neurite instead involved the polar concentration of the cell adhesion molecule N-cadherin. Added N-cadherin could be used to artificially specify neurite position, which would then signal the rearrangement of the internal organelles in a cytoskeleton-dependent fashion. Similar early polarization of N-cadherin was observed in embryonic neurons in situ. Furthermore, embryos with defective neuronal N-cadherin failed to properly align their neurons and had defects in neuronal migration. Thus, localized N-cadherin signaling appears to provide a cornerstone for very early events in hippocampal neuron polarization and outgrowth.

EMBO J. 10.1038/emboj.2012.41 (2012).

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