The role of cell adhesion molecule L1 in axonal extension, growth cone motility, and signal transduction.

Axonal pathfinding is a complex process dependent on cell-cell and cell-matrix interactions. L1 is a cell adhesion molecule that is abundant in the nervous system and that is concentrated on axons. As a culture substrate, L1 is a potent promoter of neurite outgrowth and elicits specific growth cone behavior. It interacts with the actin cytoskeleton via an ankyrin linkage and promotes specific distribution of F-actin within the growth cone. In addition, L1 has been implicated in signal transduction. For example, L1 is associated with kinases, L1-L1 binding regulates second messenger systems, and mutations in the L1 gene in humans result in abnormalities in the development of the corticospinal tract and corpus callosum. In this short review, recent advances in understanding the way in which L1 regulates growth cone behavior will be discussed.