The role of intracellular calcium and RhoA in neuronal migration

The successive steps involved in cell migration include extension of the leading process, followed by translocation of the soma and retraction of the trailing process. These events require the coordinated activity of various intracellular signaling mechanisms. Recent evidence suggests that the intracellular distribution of calcium ions and of the Rho guanosine triphosphatase (RhoGTPase), RhoA, are important components of these mechanisms. During migration, the growth cone of the leading process senses guidance cues present in the extracellular environment. These cues, acting through appropriate receptors on the growth cone, induce changes in the concentration of calcium, both in the growth cone and in the soma. These changes in the distribution of calcium cause a redistribution of intracellular RhoA and the eventual translocation of the soma. The trailing process is retracted as the cell moves forward.