Dendroaxonal Transcytosis of Transferrin in Cultured Hippocampal and Sympathetic Neurons

Agnès Hémar, Jean-Christophe Olivo, Edward Williamson, Rainer Saffrich, Carlos G. Dotti
1997 Journal of Neuroscience  
Previous studies using overexpressed polymeric immunoglobulin receptor in cultured neurons have suggested that these cells may use a dendroaxonal transcytotic pathway (Ikonen et al., 1993; de Hoop et al., 1995) . By using a combination of semiquantitative light microscopy, video microscopy, and a biochemical assay, we show that this pathway is used by the endogenous ligand transferrin (Tf) and its receptor. Labeled Tf added to fully mature hippocampal neurons changes the intracellular
more » ... on of its receptor from preferentially dendritic shortly after addition to dendritic and axonal at longer times. Incubation of living neurons with (caged)FITC-Tf followed by uncaging in the dendrites results in the later appearance of fluorescence in the axon of the same cell. In "chambered" sympathetic neurons in culture, 125 I-Tf or iron as 55 Fe-Tf added to the cell body/dendrite chamber is recovered in the axonal chamber, showing that internalized ligand from the cell bodydendrite area is released at the axonal end. Finally, we show that excitatory neurotransmitters increase Tf receptor transcytosis, whereas inhibitory neurotransmitters reduce it. The dendritic uptake, transcytotic transport, and axonal release of physiologically active Tf demonstrated here could be envisioned for other trophic factors and therefore have important consequences for neuronal anterograde target maturation. Moreover, the changes in transcytosis after neurotransmitter addition may be important in the cellular responses that follow electrical activation.
doi:10.1523/jneurosci.17-23-09026.1997 pmid:9364049 fatcat:d6jfv7pabfe5pe7q3vuaolkwhu