The glycosyltransferase fringe regulates glial cell differentiation and axon patterning in the drosophila CNS /

In the Drosophila CNS, neurons and glia communicate to regulate cell survival, gene expression and differentiation, although the precise mechanisms remain unclear. I have genetic evidence to indicate that the glycosyltransferase Fringe (fng) is required for both glial cell differentiation and neuronal axon guidance in the embryonic ventral nerve cord (VNC). fng activity is known to modify signaling through the Notch (N) receptor, and fng-dependent glycosylation of N changes the affinity of the receptor for its two known ligands, Serrate (Ser) and Delta (Dl). I found that N is widely expressed in both neurons and glia during axon outgrowth stages while Ser and Dl are restricted to unique subsets of neurons. fng is expressed in a subset of glia in the VNC and is necessary for the correct glial specific expression of the transcription factor Prospero. Prospero expression can be induced by axon-derived N ligands or by activation of the N pathway specifically in glia. Conversely, inhibition of N signaling in glia abolishes Prospero expression. I have also found that fng activity is required for axon patterning and speculate that this function is also dependant on glia-specific expression of the gene. My work suggests that fng-dependent activation of the N pathway is important for axon-glia interactions during the development of the embryonic nervous system