Imaging the dynamics of actin-associated proteins in motile cells using ultra-fast, multi-spectral TIRF microscopy
Final Report Abstract
We studied the biogenesis and function of supramolecular protein assemblies collectively called the synaptic cytomatrix. This term covers both the cytomatrix of active zone (CAZ), i.e. a complex assembled on the presynaptic side of synaptic junctions, and the postsynaptic density (PSD), i.e. an analogous but moleculary distinct complex of proteins assembled on the postsynaptic side. While we had studied these two complexes in a comparative fashion in the first two funding periods, we emphasized two new aspects, first, we focussed on the interdependence of these two complexes and found molecules and molecular interactions occurring in the PSD that transsynaptically regulate distinct steps of the assembly and maturation of the presynaptic CAZ. Second, we established and applied a long-term live imaging approach that allowed us to follow the dynamics of individual PSDs and Azs over many hours and days. This approach revealed activity-dependent and activity-independent remodelling events occurring on a time scale of hours to days, and allowed us to propose a model that may explain how synapses within neuronal networks maintain their properties at the population level despite changes occurring on the single synapse level.
