Edwin R. Chapman, Ph.D.

Title
Investigator, Howard Hughes Medical Institute
Department
Department of Physiology
Institution
University of Wisconsin-Madison
Address
1111 Highland Ave.
Room 5505
City, State, Zip
Madison, WI 53706
Phone
(608) 263-1762
E-mail
chapman[at]wisc.edu
Website
http://neuro.wisc.edu/chapman/Chapman_Lab/Home.html
Research Field
Neuroscience
Award Year
1999

Research

Our lab has several interests related to the mechanisms involved with membrane fusion, synaptic transmission, and synaptic plasticity: Our four main research projects relate to 1) The nanomechanics of Ca2+-triggered membrane fusion. These studies involve the analysis of a number of Ca2+-binding proteins (synaptotagmin, Doc2, Otoferlin, Rabphilin, etc.), as well as a number of other accessory proteins (nSec1, complexin, munc13, etc.) that regulate the core of the fusion apparatus - the SNARE complex - to control fusion reactions. We employ a diverse range of research tools to study membrane fusion including biophysical (electrophysiology, imaging etc.) and time-resolved biochemical (reconstituted fusion, stopped-flow kinetics, SPR, ITC etc.) techniques. 2) How changes in the membrane fusion machinery underlie aspects of synaptic plasticity. Using electrophysiological approaches and modern microscopy approaches (confocal, TIRF, 2-photon etc.) we are reconstituting and studying simple synaptic circuits to further our understanding of how connectivity impacts synaptic transmission, and to study the phenotypes exhibited by neurons cultured from genetically modified mice. 3) Structure and function of fusion pores. We study the structure and dynamics of fusion pores in neuroendocrine cells using carbon fiber amperometry and in neurons using optical approaches with single vesicle resolution. In our view, synaptic vesicle exocytosis often involves a kiss-and-run mechanism in which open fusion pores close without dilating to give rise to full fusion and bilayer merger. 4) Elucidation of the receptors, entry pathways, and the molecular basis for translocation across membranes, of Botulinum (BoNT) and Tetanus neurotoxins (TeNT). We are in the process of identifying the cell surface receptors, entry pathways, and mechanisms of translocation of these toxins. We are also using quantum dots to track their movement and putative transcytosis in simple neuronal circuits, and we are building 'designer' toxin-receptor pairs to widen the range of cells that these toxins can enter.