Glial-derived TNF/Eiger signaling promotes somatosensory neurite sculpting

The selective elimination of inappropriate projections is essential for sculpting neural circuits during development. The class IV dendritic arborization (C4da) sensory neurons of Drosophila remodel the dendritic branches during metamorphosis. Glial cells in the central nervous system (CNS), are required for programmed axonal pruning of mushroom body (MB) γ neurons during metamorphosis in Drosophila. However, it is entirely unknown whether the glial cells are involved in controlling the neurite pruning of C4da sensory neurons. Here, we show that glial deletion of Eiger (Egr), orthologous to mammalian tumor necrosis factor TNF superfamily ligand, results in dendrite remodeling deficiency of Drosophila C4da sensory neurons. Moreover, the attenuation of neuronal Wengen (Wgn) and Grindelwald (Grnd), the receptors for TNF ligands, is also examined for defects in dendrite remodeling. We further discover that Wgn and Grnd facilitate dendrite elimination through the JNK Signaling. Overall, our findings demonstrate that glial-derived Egr signal links to the neuronal receptor Wgn/Grnd, activating the JNK signaling pathway and promoting developmental neuronal remodeling. Remarkably, our findings reveal a crucial role of peripheral glia in dendritic pruning of C4da neurons.