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.
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.
|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|
|Zhang, Zhen; Wu, Yao; Wang, Zhao et al. (2011) Release mode of large and small dense-core vesicles specified by different synaptotagmin isoforms in PC12 cells. Mol Biol Cell 22:2324-36|
|Wang, Dongsheng; Zhang, Zhen; Dong, Min et al. (2011) Syntaxin requirement for Ca2+-triggered exocytosis in neurons and endocrine cells demonstrated with an engineered neurotoxin. Biochemistry 50:2711-3|
|Zhang, Zhen; Jackson, Meyer B (2010) Membrane bending energy and fusion pore kinetics in Ca(2+)-triggered exocytosis. Biophys J 98:2524-34|
|Zhang, Zhenjie; Zhang, Zhen; Jackson, Meyer B (2010) Synaptotagmin IV modulation of vesicle size and fusion pores in PC12 cells. Biophys J 98:968-78|
|Zhang, Zhen; Hui, Enfu; Chapman, Edwin R et al. (2010) Regulation of exocytosis and fusion pores by synaptotagmin-effector interactions. Mol Biol Cell 21:2821-31|
|Jackson, Meyer B (2010) SNARE complex zipping as a driving force in the dilation of proteinaceous fusion pores. J Membr Biol 235:89-100|
|Zhang, Zhen; Hui, Enfu; Chapman, Edwin R et al. (2009) Phosphatidylserine regulation of Ca2+-triggered exocytosis and fusion pores in PC12 cells. Mol Biol Cell 20:5086-95|
|Zhang, Zhenjie; Bhalla, Akhil; Dean, Camin et al. (2009) Synaptotagmin IV: a multifunctional regulator of peptidergic nerve terminals. Nat Neurosci 12:163-71|
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