Neurons are highly polarized cells with distinct domains that mediate specialized functions. Incoming signals from other neurons are generally detected at synapses localized to the dendrites and cell body. The outgoing signal is conducted via the axon to the nerve terminal, where the resulting depolarization causes an influx of calcium and the release of neurotransmitter by fusion of synaptic vesicles with the presynaptic plasma membrane. These functional differences are reflected in differences in the distributions of specific proteins and organelles. For example, neurotransmitter receptors must be targeted to postsynaptic membrane specializations at dendrites, while synaptic vesicles and their constituent proteins are concentrated at the nerve terminal.
The specific aims of this proposal are designed to determine the mechanism mediating the specific targeting of synaptic vesicle proteins to the nerve terminal and, ultimately, their assembly into synaptic vesicles. Hippocampal neurons grown at low density in tissue culture develop the characteristic polarized morphology of neurons in vivo. Synaptic vesicle proteins are enriched in the axon, while proteins such as the transferrin receptor are localized to the somatodendritic region. We will use this system to investigate the amino acid sequences that are responsible for the targeting of synaptic vesicles to the axon, and ultimately to synaptic vesicles. We will identify the signals responsible for the sorting of the synaptic vesicle protein synaptobrevin to the nerve terminal. We will determine if sorting to the axonal or somatodendritic domain is mediated by different determinants, and how those determinants interact to create a polarized distribution of proteins in the neuron. Finally, we will determine whether sorting determinants are conserved between different types of regulated secretory vesicles. With these results in hand, we will have taken the first step towards understanding the complex mechanism that results in the formation of synaptic vesicles during development and during recycling at the nerve terminal.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
2R01NS027536-04A2
Application #
2266460
Study Section
Neurology C Study Section (NEUC)
Project Start
1991-05-01
Project End
2000-05-31
Budget Start
1995-07-01
Budget End
1996-05-31
Support Year
4
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Harvard University
Department
Biology
Type
Schools of Medicine
DUNS #
082359691
City
Boston
State
MA
Country
United States
Zip Code
02115
Buckley, K M; Melikian, H E; Provoda, C J et al. (2000) Regulation of neuronal function by protein trafficking: a role for the endosomal pathway. J Physiol 525 Pt 1:9-Nov
Provoda, C J; Waring, M T; Buckley, K M (2000) Evidence for a primary endocytic vesicle involved in synaptic vesicle biogenesis. J Biol Chem 275:7004-12
Melikian, H E; Buckley, K M (1999) Membrane trafficking regulates the activity of the human dopamine transporter. J Neurosci 19:7699-710
West, A E; Neve, R L; Buckley, K M (1997) Targeting of the synaptic vesicle protein synaptobrevin in the axon of cultured hippocampal neurons: evidence for two distinct sorting steps. J Cell Biol 139:917-27
West, A E; Neve, R L; Buckley, K M (1997) Identification of a somatodendritic targeting signal in the cytoplasmic domain of the transferrin receptor. J Neurosci 17:6038-47
Morimoto, T; Popov, S; Buckley, K M et al. (1995) Calcium-dependent transmitter secretion from fibroblasts: modulation by synaptotagmin I. Neuron 15:689-96
Feany, M B; Yee, A G; Delvy, M L et al. (1993) The synaptic vesicle proteins SV2, synaptotagmin and synaptophysin are sorted to separate cellular compartments in CHO fibroblasts. J Cell Biol 123:575-84