Immunoglobulin Superfamily proteins SYG-1/IrreC/NEPH1 and SYG-2/SNS/Nephrin define synaptic location and synaptic partner choice of HSNL neurons in C. elegans.

We have analyzed synaptic specificity and synapse formation of a motor neuron, HSNL in C. elegans (Fig.2-1). We discovered that a pair of Immunoglobulin Superfamily proteins, SYG-1 and SYG-2, is essential for the synaptic choice of HSNL (Shen and Bargmann, 2003; Shen et al., 2004). In syg-1 or syg-2 mutants, presynaptic neuron HSNL contacts its normal synaptic partners but fails to form synaptic connections with them. Instead, ectopic synapses are formed onto abnormal postsynaptic targets. SYG-1 and SYG-2 both localize to synapses and bind to each other, acting as receptor and ligand. SYG-1 functions cell autonomously in the presynaptic neuron. SYG-2 functions in the guidepost cells, a group of epithelial cells that is essential for the correct formation of HSNL synapses (Shen and Bargmann, 2003; Shen et al., 2004).

Fig. 2-1