Abstract
Syntabulin, a vesicle cargo-protein interacting with kinesin-1, transports syntaxin-1 and mitochondria in the axon to the presynaptic terminal. To examine functional significance of syntabulin as a vesicle cargo in presynaptic neuron, synaptic transmission was examined at a cholinergic model synapse formed between rat sympathetic ganglion neurons in culture. Expression of the kineshin-1 binding domain of syntabulin (KBD) in the presynaptic neuron should disrupt the interaction and significantly reduced the incidence of synaptic coupling, measured by recording excitatory postsynaptic potentials (EPSPs), on 10, 17 and 24 days in culture. This finding suggests that syntabulin plays an important role in the synapse development. Furthermore, in long-term cultured neurons, transfection of KBD in presynaptic neurons reduced the amplitude of EPSPs (48%) in comparison with that in control synapses transfected with EGFP-DNA. In general, the synaptic transmission reduces with repetitive stimulations. KBD transfection accelerated the reduction of synaptic transmission with high frequency stimulation at 1 Hz, but not with low frequency stimulation at 0.3 or 0.1 Hz. In addition, the recovery of EPSP amplitude after depletion of synaptic vesicles in the presynaptic terminal with train stimulation at 5 Hz for 4 min remarkably slowed down in the KBD expressed synapse. Injection of ATP reversed the slowed down recovery. These findings suggest that syntabulin interacting with kinesin-1 functions in a mature synapse to maintain synaptic transmission. [J Physiol Sci. 2008;58 Suppl:S123]
