Neurotransmitters and hormones are released by Ca2+triggered exocytosis, whereby a vesicle fuses with the plasma membrane of a cell and expels its content into the extracellular space. This project has focused on the fusion pore, the initial fluidic passage between the vesicle interior and the outside of a cell. Studies of the fusion pore have given us valuable insights into the mechanism of exocytosis and the roles of specific molecules in the regulation of membrane fusion. The previous funding cycle made progress in identification of some of the fusion pore-forming proteins, and developed new techniques that will allow us to achieve these goals more effectively. We will use these new methods to perform definitive experiments on the role of synaptobrevin, a key protein involved in exocytosis, and determine whether synaptobrevin is a structural component of the fusion pore. Parallel studies of fusion pore manipulations between the PC12 cells, chromaffin cells, and neurons from the brain will define how fusion pore function influences the speed of neurotransmitter release at synapses. New results on membrane elasticity and exocytosis have allowed us to expand the scope of this study and determine how proteins can induce curvature in lipid membranes in order to shape and remodel them. Finally, experiments in PC12 cells and chromaffin cells will test a new theory that energy stored in helix-coil junctions serve as a driving force to bend membranes.

Public Health Relevance

By gaining a deeper understanding of the mechanisms of exocytosis we will learn how the nervous system controls different forms of chemical signaling employed during information processing and mental function. This will help us understand how to treat medical problems involving impaired mental function such as mental illness, learning disorders, and drug abuse.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Study Section
Special Emphasis Panel (ZRG1)
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Stewart, Randall R
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University of Wisconsin Madison
Schools of Medicine
United States
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Chiang, Chung-Wei; Chang, Che-Wei; Jackson, Meyer B (2018) The Transmembrane Domain of Synaptobrevin Influences Neurotransmitter Flux through Synaptic Fusion Pores. J Neurosci 38:7179-7191
Jackson, Meyer B (2017) Chemistry in a vesicle. J Gen Physiol 149:893-896
Chang, Che-Wei; Chiang, Chung-Wei; Jackson, Meyer B (2017) Fusion pores and their control of neurotransmitter and hormone release. J Gen Physiol 149:301-322
Chang, Che-Wei; Chiang, Chung-Wei; Gaffaney, Jon D et al. (2016) Lipid-anchored Synaptobrevin Provides Little or No Support for Exocytosis or Liposome Fusion. J Biol Chem 291:2848-57
McMahon, Shane M; Chang, Che-Wei; Jackson, Meyer B (2016) Multiple cytosolic calcium buffers in posterior pituitary nerve terminals. J Gen Physiol 147:243-54
Jackson, Meyer B (2016) The Hydrophobic Effect in Solute Partitioning and Interfacial Tension. Sci Rep 6:19265
Chang, Che-Wei; Jackson, Meyer B (2015) Synaptobrevin transmembrane domain influences exocytosis by perturbing vesicle membrane curvature. Biophys J 109:76-84
Chang, Che-Wei; Hui, Enfu; Bai, Jihong et al. (2015) A structural role for the synaptobrevin 2 transmembrane domain in dense-core vesicle fusion pores. J Neurosci 35:5772-80
McMahon, Shane M; Jackson, Meyer B (2014) In situ Ca2+ titration in the fluorometric study of intracellular Ca2+ binding. Cell Calcium 56:504-12
Yoo, Jejoong; Jackson, Meyer B; Cui, Qiang (2013) A comparison of coarse-grained and continuum models for membrane bending in lipid bilayer fusion pores. Biophys J 104:841-52

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