The region-specific activities of lipid rafts during axon growth and guidance

The generation and control of cell polarity is a fundamental mechanism for directed migration of the cell. In developing neurons, the axonal growth cone recognizes environmental molecular cues and migrates toward its correct target, thereby forming neuronal networks. The spatial information provided by environmental cues directs axon growth and guidance through generating polarity of intracellular signals and cytoskeletal organization in the growth cone. This polarization process is dependent on lipid rafts, specialized microdomains in the cell membrane. Lipid rafts in specific regions of the growth cone are involved in axon growth and guidance. For example, forward migration of the growth cone requires raft membranes in its leading front. Recent experiments have suggested that lipid rafts function as a platform for localized signaling downstream of adhesion molecules and guidance receptors. The rafts assemble into an active membrane domain that captures and reorganizes the cytoskeletal machinery. In this way, the spatial control of signaling through raft membranes plays a critical role in translating extracellular information into polarized motility of the growth cone.