miR-7 Buffers Differentiation in the Developing Drosophila Visual System

Publication date: 8 August 2017
Source:Cell Reports, Volume 20, Issue 6
Author(s): Elizabeth E. Caygill, Andrea H. Brand
The 40,000 neurons of the medulla, the largest visual processing center of the Drosophila brain, derive from a sheet of neuroepithelial cells. During larval development, a wave of differentiation sweeps across the neuroepithelium, converting neuroepithelial cells into neuroblasts that sequentially express transcription factors specifying different neuronal cell fates. The switch from neuroepithelial cells to neuroblasts is controlled by a complex gene regulatory network and is marked by the expression of the proneural gene l'sc. We discovered that microRNA miR-7 is expressed at the transition between neuroepithelial cells and neuroblasts. We showed that miR-7 promotes neuroepithelial cell-to-neuroblast transition by targeting downstream Notch effectors to limit Notch signaling. miR-7 acts as a buffer to ensure that a precise and stereotypical pattern of transition is maintained, even under conditions of environmental stress, echoing the role that miR-7 plays in the eye imaginal disc. This common mechanism reflects the importance of robust visual system development.

Graphical abstract

Teaser

Caygill and Brand show that miR-7 buffers optic lobe neural stem cell production to ensure that a precise and stereotypical pattern is maintained, even under conditions of environmental stress. These results echo the role that miR-7 plays in the eye imaginal disc, emphasizing the importance of robust visual system development.


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