Increase in synaptic vesicle proteins in synapsin-transfected NG108-15 cells: A subcellular fractionation study

We have examined the subcellular distribution of synapsins and synaptophysin in density gradients from synapsin‐ and vector‐transfected NGlO8‐15 cells, since we recently found that transfection of synapsin IIb cDNA into neuroblastoma X glioma hybrid cells (NG108‐15) resulted in cell lines that had a more neuronal phenotype than controls. The increase in synapsins and synaptophysin in the transfected cells was maximal in the region of the gradient containing small synaptic vesicles. The transferrin receptor, a marker for early endosomes, did not increase in the synapsin‐containing fractions in the transfected cells. Secretogranin I, a soluble protein stored in and secreted from large dense cored vesicles, showed a very pronounced increase in the dense regions of gradients from transfected cells. These subcellular fractionation data suggest a possible role for the synapsins in the regulation of synaptic vesicle function. © 1995 Wiley‐Liss, Inc.