| Popis: |
Neurotransmitter release relies on the regulated fusion of synaptic vesicles (SVs) that are tightly packed within the presynapse of neurons. The mechanism by which SVs are anchored at the presynapse while preserving their ability to dynamically recycle thereby supporting neuronal communication remains unknown. Synapsin2a tetramerization was recently suggested to cluster SV in presynapses. Here, we used Dual-pulse sub-diffractional Tracking of Internalised Molecules (DsdTIM) to simultaneously track SVs from the recycling and reserve pools, in live hippocampal neurons. The reserve pool displays a lower presynaptic mobility compared to the recycling pool and exhibits a more mobile axonal pool. Synapsin1-3 triple knockout (SynTKO) selectively increased the reserve pool mobility. Re-expression of wild-type Synapsin2a, but not the tetramerization-deficient mutant K337Q, fully rescued these effects. Tracking Synapsin2aK337Q-mEos3.2 revealed altered synapsin activity-dependent presynaptic translocation and nanoclustering. Synapsin2a tetramerization therefore controls its own presynaptic nanoclustering allowing dynamic immobilisation of the reserve pool at the presynapse. |
