Differential induction and intracellular localization of SCG10 messenger RNA is associated with neuronal differentiation

The differentiation of neurons involves the establishment of distinct molecular compartments which regulate neuronal shape and function. This requires targeting of specific gene products to growth-associated regions of the neuron. We have investigated the temporal and spatial regulation of SCG10 gene expression during neuronal differentiation. There are two SCGIO messenger RNAs, 1 and 2 kb in length, which encode the same growth-associated protein. These messenger RNAs were found to be differentially regulated during the onset of neurite outgrowth in early rat cerebellum development. In PC12 cells, the two SCG10 messenger RNAs were shown to be differentially induced by nerve growth factor. Regulation of the 2 kb messenger RNA, but not the 1 kb messenger RNA, is dependent on the differentiation of PC 12 cells, indicating post-transcriptional regulation of SCG10 expression during neurite outgrowth. Spatial regulation of the 2 kb SCG10 messenger RNA distribution during brain development was examined byin situ hybridization. The 2 kb messenger RNA was found to be localized to the neuronal pole where neurite outgrowth was occurring, within differentiating neuronsin vivo. Intracellular localization of SCG10 messenger RNA was also observed in differentiating primary cultured neurons, with the 2 kb messenger RNA transported into growing neurites during the development of neuronal polarity. In neurons which had developed polarity, the 2 kb SCG10 messenger RNA was consistently found in the cell body and axon.