Summer Research Abstract

Tiannan Zhan, Sarah Ames

Dr.Karen F. Greif



The role of Synaptotagmin-1 Ca2+ binding domains in regulating neuronal morphology


Synaptotagmin-1(syt1) is a Ca2+ binding protein which is well-characterized for its function in controlling neurotransmitter release; however, syt1 expression is found in various types of neurons before the formation of synapses. Previous studies indicate that syt1 influences neuronal morphology by regulating the formation of axonal filopodia and branches. The researchers examined its effect by comparing the results of the knockdown and the overexpression of synaptotagmin-1 on the number of filopodia and branches.

These findings lead to our hypothesis that that syt1 may regulate the stabilization of filopodia and branches downstream of endogenous calcium transients. Other studies indirectly looked at the link between calcium influxes and syt1 pre-synaptogenesis function by both opening and blocking Ca2+ channels. In order to provide more direct evidence of that process and further explore the role of syt1, we aim to compare the  expression of wild type syt1 and mutated syt1 with both Ca2+ domains disabled via lentivirus-mediated infection of embryonic chicken forebrain neurons. We predict that the mutated syt1 would yield significantly fewer filopodia and axonal branches in contrast to wild-type syt1 expression. Viral infection is proved to be an effective way to transfect desired DNA into targeted cells, and lentivirus is often used to infect nondividing cells like neurons.  To prepare the functional recombinant lentivirus, we plan to amplify the plasmids containing desired constructs, generously donated by Edwin Chapman of the University of Wisconsin. We can then construct and cultivate the lentivirus in the following weeks, along with titer testing and viral transfection into neurons.