Mentor: Dr. Karen Greif
Within the nervous system, nerve cells communicate through structures known as synapses, which function by releasing the contents of small vesicles containing neurotransmitters at their presynaptic terminals when the proper stimulus is applied. Developing nerve cells need to grow and extend into axons, the elongated process that contains the synapse, and at its end synthesize and transport synaptic proteins needed for function to the synaptic terminals. Several synaptic proteins have been identified that have defined their roles in synaptic function: synaptotagmin (syt), synaptobrevin (VAMP), SNAP-25, and syntaxin. These proteins are expressed in developing neurons several days before any synapses are formed. Previous research done in our laboratory suggests that the vesicular proteins, syt and VAMP, are transported earlier down the growing axon than pre-synaptic membrane proteins, SNAP-25 and syntaxin. These data suggest that different synaptic proteins may utilize different transport mechanisms, which cause them to be transported at different times down the axon. Our specific experiment therefore is to determine the time course of transport of the synaptic proteins in the developing sympathetic neurons in vitro. Double labeling of the cells using fluorescent antibody markers through a process called immunocytochemistry will be employed to compare the patterns of transport in different synaptic proteins, specifically synaptotagmin, syntaxin, VAMP, and SNAP-25. Image analysis will then be conducted using confocal microscopy to analyze these fluorescent-labeled antibody proteins to note the distribution and patterning of the synaptic proteins. Why certain proteins are apparently transported earlier than others and what roles these proteins play in early neuron development will be studied in other experiments using the data collected from this research.
Supported by NIH AREA grant #1R15NS4303.