PROTEIN-TRANSPORT TO THE DENDRITIC PLASMA-MEMBRANE OF CULTURED NEURONS IS REGULATED BY RAB8P

In the companion paper (Huber, L. A., S. W. Pimplikar, R. G. Parton, H . Virta, M. Zerial, and K. Simons. J. Cell Biol. 123:35-45) we reporte d that the small GTPase rab8p is involved in transport from the TGN to the basolateral plasma membrane in epithelia. In the present work we investigated the localization and function of rab8p in polarized hippo campal neurons. By immunofluorescence microscopy we found that rab8p l ocalized preferentially in the somatodendritic domain, and was exclude d from the axon. Double-labeling immunofluorescence showed that some o f the rab8p co-localized in the dendrites with the Semliki Forest Viru s glycoprotein E2 (SFV-E2). An antisense oligonucleotide approach was used to investigate the role of rab8p in dendritic transport of newly synthesized viral glycoproteins. Antisense oligonucleotides correspond ing to the initiation region of the rab8 coding sequence were added to the cultured neurons for four days. This treatment resulted in a sign ificant decrease in cellular levels of rab8p and transport of SFV-E2 f rom the cell body to the dendrites was significantly reduced. However, no effect was observed on axonal transport of influenza HA. From thes e results we conclude that rab8p is involved in transport of proteins to the dendritic surface in neurons.