Research in the Blanpied Lab examines protein trafficking mechanisms at synapses, and seeks to understand how these mechanisms are used to regulate synaptic transmission.
The dendrites of neurons receive and integrate inputs from hundreds or thousands of partner cells, and most of this input arrives at highly specialized sites called synapses that are distributed over the dendritic tree. Improper regulation of synaptic transmission is implicated in an enormous variety of psychiatric disorders: an imbalance of glutamatergic neurotransmission in particular has been identified in the pathophysiology of diseases ranging from schizophrenia and autism to epilepsy and addiction, and increasing evidence suggests that excitatory synapses are among the earliest targets of Alzheimer’s Disease (AD) pathogenesis. A key means of synaptic regulation is the control of the number of postsynaptic neurotransmitter receptors, and so understanding the mechanisms involved has broad implications not only for understanding the etiology of many diseases but more generally for defining the cellular basis of nervous system function and disorder.
We focus on processes that operate rapidly and very locally to regulate synaptic function on a moment-to-moment basis. These mechanisms are of particular interest because they likely underlie the initial stages of memory formation, and their perturbation produces severe and long-lasting damage to synaptic and neuronal morphology. Mechanisms we are studying currently include the continuous internalization and recycling of synaptic receptors, the postsynaptic actin cytoskeleton that controls postsynaptic morphology and regulates receptor trafficking in many ways, the organization and dynamics of the proteins at each synapse that control receptor number and position at the synapse, and the trans-synaptic molecular bridges that align presynaptic nerve terminals with postsynaptic specializations.
Understanding the complex set of molecular reactions that underlie endocytosis and other trafficking events requires examining these events in live cells. Thus, the lab has turned to high-resolution, high-speed, multi-color confocal and super-resolution imaging of proteins in cultured neurons. These approaches provide a way of examining the kinetics and spatial features of the molecular events at individual living synapses. We utilize a number of novel assays centered on single-molecule localization and tracking using Photoactivated Localization Microscopy (PALM) to examine protein positioning and movement at the synapse in living cells at the highest resolution possible. These tools provide the perfect complement to whole-cell and single-channel electrophysiological assays, which naturally track receptor function at high speed but typically with little or no spatial resolution. The lab aims to combine these approaches with molecular perturbation of protein function to provide unprecedented spatial, temporal, and molecular understanding of the protein trafficking events in spines.
We are grateful to a number of sources for supporting our research. Our principle support is from the NIMH through R01MH080046 and through a collaborative R01 MH096376 in the CRCNS mechanism that we share with Sri Raghavachari at Duke University. We also collaborate with Sri on a project funded by The Broad Foundation. The Dana Foundation provides important support for the development of PALM in the lab, and its application toward understanding synaptic dysfunction in Alzheimer’s Disease. We also are grateful to the Katherine D. and Theodore J. Carski Foundation for their support of the Department and our lab.