Figure 7.

Raw is required for dendrite degeneration. Individual dendrite branches of ddaE sensory neurons, labeled by expression of UAS-mCD8-GFP with the 221-Gal4 driver, were surgically transected using a pulsed dye laser in flies coexpressing expressing Dcr2 and either control RNAi (rtnl2 RNAi, VDRC 33320) or raw RNAi (VDRC 101255). A, Example images of ddaE neurons 0 and 18 h postdendrotomy are shown. Degeneration is characterized by membrane blebbing and loss of continuity in the primary comb (red line). Scale bar, 20 μm. B, Quantification of dendrites that remain intact 18 h postdendrotomy is shown in the graph. Reduction of raw expression via RNAi protects dendrites comparably to overexpression of the protective enzyme Nmnat, as in Chen et al. (2016). Rearing animals in the presence of GNE-3511, which inhibits DLK (Patel et al., 2015) and Wnd-mediated phenotypes in ddaE neurons (Feng et al., 2019), caused no significant change to the raw-RNAi phenotype compared with animals reared in the presence of the DMSO vehicle (B), but did cause a modest reduction in expression of the puc-GFP reporter (C). D, In contrast to a previously described mechanism for dendrite protection (Chen et al., 2012), raw mutants do not show increased microtubule dynamics. The number of growing microtubule plus ends labeled by EB1::GFP were measured in UAS-Dicer2;221Gal4, UAS-EB1::GFP larvae expressing UAS- rtnl2 (control) RNAi or UAS-raw-RNAi. Statistical significance was calculated using one-way ANOVA. ***p < 0.001, **0.001 < p < 0.01, ns represents p > 0.05 (p = 0.15). n ≥ 14 ddaE neurons per condition.