Understanding The Role Of Endocytosis In Synaptic Partner Recognition In C. elegans

The nervous system is a network of excitable cells called neurons, which consist of a cell body and long extensions called neurites. Neurons communicate with one another through specialized connections called synapses. To form these connections, neurons must first recognize the correct synaptic partners from the many cells in a target region. The ability of neurites to identify and form synapses with correct synaptic partners is called synaptic partner recognition (SPR). We are interested in understanding whether synaptic vesicle cycling plays a role in maintaining correct SPR.  To address this question, we have labeled synapses between specific pre- and postsynaptic neurons in the genetic model organism C. elegans using the transgenic fluorescent marker NLG-1 GRASP (GFP Reconstitution Across Synaptic Partners).  We are testing several mutants with defects in exo- and endocytosis for roles in SPR. We propose that synaptic activity via cycling of presynaptic vesicles is required to maintain correct SPR. We have found that several endocytosis mutants have defects in SPR, suggesting that synaptic vesicle cycling is necessary for proper SPR. To determine if endocytosis is required for establishment or maintenance of correct SPR, time courses will be performed.  To determine whether the presynaptic or postsynaptic function is necessary for SPR, cell-specific rescue experiments will be performed. Understanding the role of these molecules in SPR may help us to understand this critical process.