Molecular mechanisms underlying axonal local protein synthesis in neurons

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Translation machinery in growth cone. Existence of ribosomes in growth cone was investigated by immunocytochemistry with anti-ribosomalprotein antibodies. Although it is widely believed that there is no ribosomes in axon, immunoreactivityagainst ribosomal proteins was recognized in growth cone of cultured dorsal root ganglia neurons and ofhippocampal neurons. In addition, several translation factors were found in growth cone of theseneurons. Precise morphological analysis of growth cone was performed by using atomic forcemicroscopy.Triggers of local translation in growth cone.Brain-derived neurotrophic factor (BDNF) and Wnt3a were identified as a trigger of local translation ingrowth cone. In addition to the [35S]methionin incorporation, puromycin-anti-puromycin immunocytochemistry method revealed that these factors activate novel protein synthesis in growth cones.These results indicate the existence of translational machinery in growth cone and strongly suggest thatlocal protein synthesis occurs in growth cones in response to certain growth factors.