Abstract
Syntabulin, interacting with kinesin-1, transports syntaxin-1 and mitochondria in the axon to the presynaptic terminal. To examine functional significance of syntabulin in presynaptic neuron, synaptic transmission was examined at a cholinergic model synapse formed between rat sympathetic ganglion neurons in culture. Knock-down of syntabulin expression with targeted small interfering RNAs (siRNAs) 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, deficit of syntabulin in presynaptic neurons reduced the amplitude of EPSPs (57%) in comparison with that in control synapses transfeted with a scrambled RNA. In general, the synaptic transmission reduces with repetitive stimulations. Syntabulin knock-down accelerates 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 a train stimulation at 5 Hz for 4 min remarkably slows down in the syntabulin impaired synapse. These findings suggest that syntabulin functions in a mature synapse to maintain synaptic transmission. [J Physiol Sci. 2007;57 Suppl:S83]
