Glia relay differentiation cues to coordinate neuronal development in Drosophila
Science 01 Sep 2017:
Vol. 357, Issue 6354, pp. 886-891
Neuronal birth and specification must be coordinated across the developing brain to generate the neurons that constitute neural circuits.
Photoreceptors achieve retinotopy by inducing their target field in the optic lobe, the lamina neurons, with a secreted differentiation cue, epidermal growth factor (EGF).
communication between photoreceptors and lamina cells requires a signaling relay through glia. In response to photoreceptor-EGF, glia produce insulin-like peptides, which induce lamina neuronal differentiation.
A key challenge during neural development is to coordinate the birth and specification of diverse neuronal and glial cell types across different brain regions.
Intercellular signaling relays are used in various contexts during development
By signaling through glia, photoreceptors may be translating a homogeneous cue (EGF) into a spatiotemporally graded one, which appears essential for diversifying (L1 to L4) neuronal fates. (iii) Glial cells may be well suited for integrating sparse cues to interpret them into stronger or more robust signals (31). Thus, by amplifying cues from photoreceptors, glia may help reduce noise or variability of the signaling outcome.