836A Poster - 13. Neural development and physiology
Thursday April 07, 2:00 PM - 4:00 PM

Authors:
Duo Cheng; Jaimy Coates ; Vanessa Auld

Affiliation: University of British Columbia

Keywords:
k. glia; c. neural stem cells

In order to establish a functional brain, neural stem cells (NSC) need to generate an abundant number of neurons and glia under tight temporal and spatial regulations. The Drosophila melanogaster’s optic lobe is a popular model to study neurogenesis as each optic lobe is generated by neuroblasts (NB) that differentiate from the columnar neuroepithelium (NE). Glia provide essential modulation to the NSC niche to ensure appropriate NSC differentiation. During the 3^rd instar larval stage, the OPC+NE are surrounded by two distinct classes of glia, the subperineurial glia (SPG) and the cortex glia (CG). Both are known to modulate the NSC niche and play a role in NSC homeostasis. Yet the tools by which glia utilize to interpret and control the NSC niche are far from being fully characterized. Here, we explored the role of a transmembrane heparan sulfate proteoglycan (HSPG), Syndecan (Sdc) in regulating the NSC niche during development. Using super-resolution microscopy, we revealed Sdc is widely expressed across the brain lobe, though we notice Sdc is particularly enriched around the NE. Pan-glial knockdown of Sdc revealed a dramatic decrease in brain lobe volume, accompanied by a reduction of the NB population size within the OPC. Moreover, we observed the lengthening of the ventral nerve cord, indicative of disruption between glia and the overlying extracellular matrix that coats the entire nervous system. While the loss of Sdc in glia did not significantly alter the level of apoptosis, it did lead to a reduction in mitotic events in the OPC. Upon further experiments, we observed pan-glial Sdc knockdown perturbed the NE morphology, and reduced Notch activity within the NE. Notch signaling is known to prevent premature differentiation of NE into medulla neuroblasts, ensuring the expansion of the NE. Therefore we are investigating the role of Sdc in mediating Notch signaling cross-talk between the subperineurial glia and the NE. We are also exploring the potential influence of cortex glia on OPC proliferation and NE morphology. Overall, our results support a novel aspect of Sdc’s role in regulating the NSC niche through glial regulation of the NE in the developing brain lobe.