Regulation of axonal proteins synthesis

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It has become accepted that the axonal compartment can autonomously synthesize proteins. This local translation provides the axon with a renewable source of proteins to respond to extracellular stimuli. Studies from the Pi's group have shown that axonal protein synthesis is triggered by neural injury and that particularly robust protein synthesis occurs in regenerating axons. This localized protein synthesis represents a mechanism that can likely be harnessed to facilitate the regeneration of axons in the adult nervous system. Despite the obvious functional significance and newly increased interests in axonal protein synthesis, we little understanding of how this process is regulated. Our preliminary studies indicate that adult axons have the potential to synthesize a complex population of more than 200 different proteins; there is clearly some specificity to choose which proteins are generated when and where. The objective of this proposal is to determine how this axonal protein synthesis is regulated. We hypothesize that axonal stimulation alters localized protein synthesis through both directing the transport of particular mRNAs into the axonal compartment and locally controlling the activity of the axonaltranslational machinery. In Aim 1, we will determine how axonal guidance cues and growth promoting stimuli modify specificity of axonal protein synthesis. The contributions of axonal transport vs. localized synthesis will be determined for each axonally synthesized protein identified. The physiological consequences of localized synthesis of these proteins in axonal growth will be addressed. In Aim 2 we will ask how the axon controls synthesis of organelle and membrane proteins and the functional relevance of these pathways to nerve regeneration. Nerve regeneration is abysmally slow and rarely successful. It has recently been recognized that injured nerve processes are capable of generating their own proteins. Our studies indicate that this may be used to enhance recovery after injury of the nervous system. The objective of this grant application is to determine how local protein synthesis in nerve processes is regulated by extracellular stimuli.