Dpp and Hedgehog promote the Glial response to neuronal damage in the developing Drosophila Visual system

Damage in the nervous system induces a stereotypical response that is mediated by glial cells. Here, we use the eye disc to explore the mechanisms involved in promoting glial cell response after neural injuries. We demonstrate that eye glia cells rapidly respond to neuronal injury by increasing in number and undergoing morphological changes, which grant them phagocytic abilities. We found that this glial response is controlled by the activity of the long-range signalling pathways, decapentaplegic (dpp) and hedgehog (hh). These pathways are activated in the damaged region and their functions are necessary for inducing glial cell proliferation and migration to the eye discs. The latter of these two processes depends on the function of the JNK pathway, which is cooperatively activated by dpp and hh signalling.