Endocytic Mechanisms and Phosphoinositide Metabolism at Synapses

Pietro De Camilli, Department of Cell Biology and HHMI, Yale University

Communication between neurons relies heavily upon the specialized form of membrane traffic responsible for the vesicular release of neurotransmitters. Membrane traffic is also involved in the control of synaptic plasticity through modulation of neurotransmitter receptor levels on the pre- and post-synaptic plasma membranes. These processes have a major impact in the development of drug addiction. A major focus of my laboratory is the elucidation of the mechanisms underlying endocytosis in neurons, with emphasis on the recycling of synaptic vesicle membranes and on the internalization of neurotransmitter receptors. Progress in this field requires developing a precise inventory of all the proteins participating in endocytosis as well as a functional characterization of these proteins using the tools of cell biology, biophysics and genetics. As studies from our and other labs have shown, the chemistry of membrane phospholipids also plays an important role in the control of endocytic traffic. Phosphorylation-dephosphorylation of inositol phospholipids, in particular, has a key regulatory role at the interface between membrane dynamics and signaling. Support from the proteomics and lipidomics cores of the Yale/NIDA Neuroproteomics Center will greatly synergize with ongoing work of the lab in the following three areas: 1) investigations of the pathways of phosphoinositide signaling at synapses and their impact on membrane traffic; 2) studies of clathrin-mediated endocytosis in neurons; 3) elucidation of mechanisms that direct post-endocytic protein and membrane traffic in the endosomal compartment of synapses. It is expected that these studies, which will rely heavily on in vitro cell culture models and on reverse mouse genetics, will provide the basis for a better understanding of altered signaling in drug addiction and will reveal new potenial targets for the treatment of addiction.