Dynamic imaging of protein machinery for synaptic plasticity in neuronal dendritic spines

Long-term synaptic plasticity underlies learning and memory and the tuning of neural circuitry. A central process involved in the plasticity of excitatory synapses is dynamic changes in the size and shape of dendritic spines. These protrusions from the dendritic shaft compartmentalise the postsynaptic protein machinery, and concentrate biochemical signals such as Ca2+ ions. Dendritic spines shrink following the induction of long-term depression (LTD), and grow during long-term potentiation (LTP). In addition, aberrant spine morphology is emerging as a critical factor in brain disorders such as autism spectrum disorders, schizophrenia and stroke. Dendritic spine structural plasticity involves an elaborate network of signalling pathways converging on protein complexes that regulate the actin cytoskeleton.

Protein interactions can be analysed by live cell imaging using FLIM-FRET (Fluorescence Lifetime Imaging - Förster Resonance Energy Transfer), which is an advanced cell imaging technique that provides a dynamic measure of the proximity of two fluorophores, and hence of two proteins with appropriate fluorescent tags.

The aim of this project is to analyse relevant protein-protein interactions in dendritic spines using FLIM-FRET in response to stimuli that induce plasticity. The study will focus on PICK1, which is essential for LTD, inhibits actin polymerisation, and interacts with a number of other proteins that are crucial for plasticity. FLIM-FRET will be used to analyse PICK1 protein interactions, with simultaneous recording of spine size. This will be done in real time, following neuronal stimulation to induce plasticity.

Our hypothesis is that the extent of these specific protein interactions governs the degree of spine shrinkage. Computational methods will be employed to test this hypothesis and build a model of dendritic spine dynamics based on specific protein-protein interactions.

This project will be carried out under the expert supervision of a multi-disciplinary team covering neuronal cell biology (Dr. Jonathan Hanley), specific expertise in FLIM-FRET (Dr. Dominic Alibhai/ Dr. Mark Jepson), and computational biology (Dr. Krasimira Tsaneva-Atanasova). The cell imaging and image analysis will be carried out in the state-of-the-art Wolfson Bioimaging Facility at the University of Bristol.

Keywords: neuroscience / neuron / synapse