Membrane organization in synaptic function and dysfunction
I am a cell biologist with a particular interest in biology of neuronal synapses. My long-term ambition is to understand the rationale of the synapse to gain control of the functionality of the nervous system in health and disease. In the meantime, I combine biochemistry with imaging to study how neurons employ membrane dynamics to maintain, adapt and modify their synapses – and how the diseased neurons fail to do so.
Dynamin-independent receptor trafficking in neurons
The eukaryotic cell harbours a diverse repertoire of endocytic mechanisms that regulate manifold aspects of homeostasis, signalling and function. In the neuron, this complexity is well documented within the framework of membrane recycling at the presynaptic terminal. Our recent findings suggest that a similar arrangement may exist at the postsynaptic compartment, where a novel pathway for receptor trafficking does not require clathrin and dynamin – the defining proteins of the classical endocytic pathway (Fig. 1). I now plan to use imaging and biochemical approaches in cultured neurons to gain a better understanding of the role this pathway plays in the physiological and pathological context of neuronal (and possibly glial) function.
Imaging synaptic geometry
Existing evidence suggests that synapses are remarkably dynamic structures that persistently undergo structural modification. So far, however, direct visualization of nanoscale synaptic dynamics has been unfeasible due to the lack of suitable methodology. I have developed an assay that utilizes the principle of trans-synaptic fluorescence resonance energy transfer (FRET) to assess the synaptic geometry (Fig. 2). I will apply this approach to established cellular paradigms of synaptic maturation, plasticity and pathology in order to delineate the mechanisms underlying synaptic dynamics, with specific aim at the multiple cell adhesion molecules resident at the synapse.
Regulation of neuronal membrane trafficking by activity and pathology – a systemic approach
In order to fulfil their function, neurons must constantly readjust their functional properties in response to the activity of the system. A crucial element of this readjustment is dynamic regulation of surface expression of neurotransmitter receptors, ion channels and other membrane proteins. Through regulation of trafficking at (or near) the synapse, neurons achieve tight control over their most fundamental properties – synaptic transmission and intrinsic excitability. While much research has been focusing on activity-regulated surface expression of particular proteins, the comprehensive picture of activity-dependent regulation of neuronal membrane trafficking is lacking and the mechanisms underlying it are poorly understood. I propose to undertake a systemic characterization of the activity-dependent regulation of neuronal surfaceome (i.e. proteins expressed at the surface of the neuron) in the context of Alzheimer’s disease, using affinity purification, proteomics and subsequent characterization by imaging and biochemistry