course: Dynamics of calcium channel organization in the presynaptic membrane
speaker: Martin Heine (Leibniz Institute for Neurobiology)abstract: The local organization and function of voltage gated calcium channels (VGCC) is for many signaling processes important, since many signaling pathways can be triggered by calcium ions. Within neurons VGCC are important for excitation-secretion coupling, particular in the presynaptic membrane of chemical synapses. The coupling between VGCC and calcium sensors on the synaptic vesicles (SV) is critical for the success of release. Already displacements of few tens of nanometers change the release probability of a synapse significantly. We used single particle tracking photoactivation localization microscopy (sptPALM), to identify the dynamics of VGCC in the axonal and presynaptic membrane. Despite the need of nanometer precise coupling between SV and VGCC, channels are quite mobile and do only transiently be stabilized in nanodomains. Within individual synapses 1-2 nanodomains are detectable, were a subpopulation of synaptic VGCC is confined. Using two natural occurring splice variants of CaV2.1 channels, which are differ substantially in the length of their C-terminus allowed us to identify a dynamic coupling between VGCC and SV. Optogenetic cross-linking was used to verify the differences in VGCC-SV coupling caused by C-terminal splicing. We propose that VGCC dynamics within the presynaptic membrane is a very efficient mechanism that contribute to short term synaptic plasticity and alter the filtering properties of synapses.
timetable:
Thu 11 Oct, 15:00 - 16:00, Aula Dini
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