抄録
SNAP-25 is thought to play a key role in synaptic vesicle fusion for neurotransmitter release. PKC can phosphorylate SNAP-25 at Ser 187, but its outcome is yet unclear. We have addressed this question at the calyx of Held synapse, using knock-in mice with their Ser 187 of SNAP-25 being replaced by Ala. Between wild-type and knock-in mice, no significant difference was found in the amplitude, kinetics or frequency of spontaneous miniature (m) EPSCs. Although the mean amplitude of evoked (e) EPSCs in knock-in mice was slightly larger than that in wild-type mice, neither the transmitter release probability nor the size of readily releasable pool of synaptic vesicles was different.Interestingly, the PKC activator PDBu showed significantly weaker effect in increasing the mEPSC frequency in the knock-in mice compared with the wild-type mice. However, the magnitude of increase in the eEPSC amplitude by PDBu was comparable between knock-in and wild-type mice. At the calyx of Held presynaptic terminal, PDBu enhanced immuno-cytochemical colocalization of SNAP-25 and the vesicle marking protein in wild-type mice, but not in knock-in mice. We conclude that phosphorylation of SNAP-25 may enhance spontaneous interactions of SNAP-25 with vesicular proteins, thereby enhancing spontaneous fusions of synaptic vesicles in the nerve terminal. [J Physiol Sci. 2008;58 Suppl:S122]
