Conserved miR-8/miR-200 Defines a Glial Niche that Controls Neuroepithelial Expansion and Neuroblast Transition

Morante J, Vallejo DM, Desplan C, Dominguez M
Magazine Dev Cell
Year 2013
Vol: Pages(start-end) 27(2):174

Neuroepithelial cell proliferation must be carefully balanced with the transition to neuroblast (neural stem cell) to control neurogenesis. Here we show that, loss of the Drosophila microRNA mir-8 (the homologue of vertebrate miR-200 family) results in both excess proliferation and ectopic neuroblast transition. Unexpectedly, mir-8 is expressed in a subpopulation of optic lobe associated cortex glia that extend processes that ensheath the neuroepithelium, suggesting that glia cells communicate with the neuroepithelium. We provide evidence that miR-8-positive glia express Spitz, a TGF-α-like ligand that triggers EGF receptor activation to promote neuroepithelial proliferation and neuroblast formation. Further, our experiments suggest that miR-8 ensures both a correct glial architecture and the spatio-temporal control of Spitz protein synthesis via direct binding to Spitz 3’UTR. Together, these results establish glial-derived cues as key regulatory elements in the control of neuroepithelial cell proliferation and the neuroblast transition.

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