Synapses

Project leader: Michael Kessels
Doctoral candidate: Astha Jain

Background and previous work
A deeper understanding of LTD and LTP requires knowledge about how the effectors, which execute the required postsynaptic rearrangements, are controlled in time and space in response to synaptic stimuli. Phosphoinositides have been implicated in adaptive signal responses in postsynapses. Recently, we have successfully established a combination of freeze-fracturing and immunogold labeling (FRIL) of PIP₂ and PIP₃ and of the phosphoinositide-binding protein syndapin I to study the molecular processes underlying LTP, LTD and excitotoxicity at high resolution at synaptic membranes.

Specific aims and working programme
Based on our recent progress it now becomes possible to visualise PIP₃, its generators (PI3Kinases) and its effectors at high resolution in both neuronal cultures and in hippocampal slices. The project therefore aims at analysing the spatio-temporal distribution of PIP₂ and PIP₃ upon different doses of neurotransmitter release resulting in LTD, LTP and excitotoxicity in a quantitative manner at nanometer resolution at the membrane of dendritic spines. Furthermore, we will address whether the spatial coordination of phosphoinositide signalling within spines occurs at the level of the enzymes that give rise to PIP₂ and PIP₃ and conduct correlation studies with PIP₂- and PIP₃-binding effector proteins suggested to play a role in synapse formation and plasticity. This will address putative phosphoinositide and effector microdomain formation processes as organisational mechanisms giving rise to structural and functional synapse adaptations under different modes of neurotransmission-induced stress.