(G) Quantification of wnt5 mutant ddaC neurons with attached primary dendrites or severed dendritic fragments at 16-18 h APF with or without the puc A251.1F3 heterozygous mutant background. Arrows indicate the soma of ddaC neurons. (F) Dendrites of a puc A251.1F3 heterozygous mutant ddaC neuron are pruned normally at 16-18 h APF. (E) wnt5 D7 mutant ddaC neurons largely prune their dendrites at 16-18 h APF in the puc A251.1F3 heterozygous mutant background. (B-D) ddaC neurons homozygous mutant for wnt5 400 (B) or wnt5 D7 (C), or transheterozygous mutant for wnt5 400/ wnt5 D7 (D), have attached primary dendrites at 16-18 h APF. (A) Dendrites are pruned in a wild-type ddaC neuron at 16-18 h APF. Wnt5 promotes dendrite pruning of c4da neurons likely by activating JNK. Published by The Company of Biologists Ltd. Thus, our work not only identifies a novel pathway involved in dendrite pruning and a new downstream target of EcRB1 in c4da neurons, but also reveals that JNK and Ecdysone signaling coordinate to promote dendrite pruning.ĭendrite pruning Drosophila Ecdysone JNK Sensory neurons Wnt5. Interestingly, our data show that JNK activity in c4da neurons remains constant from larval to pupal stages but the expression of Fos is specifically activated by ecdysone receptor B1 (EcRB1) at early pupal stages, suggesting that ecdysone signaling provides temporal control of the regulation of dendrite pruning by JNK signaling. We find that loss of JNK or its canonical downstream effectors Jun or Fos led to dendrite-pruning defects in c4da neurons.
Here, we have investigated the function of JNK signaling in dendrite pruning using Drosophila class IV dendritic arborization (c4da) neurons as a model. Developmental pruning of axons and dendrites is crucial for the formation of precise neuronal connections, but the mechanisms underlying developmental pruning are not fully understood.
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