How are cell-surface interactions linked with the establishment of neuronal polarity?
Establishment of polarity is an essential process during neuron migration and differentiation, and the signaling pathways leading to polarization of the cytoskeleton are topics of intense interest. The observations of Bron et al. [8] provide an impetus to undertake further experiments in this direction. They report that knock-down of MICAL3 (molecule interacting with CasL) leads to the most severe ectopic motor neuron phenotype in the chick ventral spinal cord. This is consistent with the convergence of several sets of signals on this intermediate of semaphorin signaling. The recently identified MICALs are a family of adaptor proteins containing multiple well conserved domains with known interactions with the cytoskeleton, in particular with microtubules, cytoskeletal adaptor proteins and other signaling proteins [31]. Indeed, a central component of the neuronal cytoskeletal structure is a microtubule array, with the centrosome or microtubule-organizing center lying at its hub. It has
