Astrocyte-dependent local neurite pruning and Hox gene-mediated cell death in Beat-Va neurons

Abstract

AbstractNeuronal remodeling is extensive and mechanistically diverse across the nervous systems of complex metazoans. To explore circuit refinement mechanisms, we screened for new neuronal subtypes in theDrosophilanervous system that undergo remodeling early in metamorphosis. We find Beat-VaMneurons elaborate a highly branched neurite network during larval stages that undergoes local neurite pruning during early metamorphosis. Surprisingly, Beat-VaMneurons remodel their branches despite blockade of steroid hormone signaling and instead depend on signaling from astrocytes to activate pruning. We show Beat-VaLneurons undergo steroid hormone-dependent cell death in posterior but not anterior abdominal segments. Correct activation of apoptotic cell death relies on segment-specific expression of the hox geneAbd-B, which is capable of activating cell death in any Beat-VaLneuron. Our work provides new model cells in which to study neuronal remodeling, highlights an important role for astrocytes in activating local pruning inDrosophilaindependent of steroid signaling, and defines a Hox gene-mediated mechanism for segment-specific cell elimination.SummaryLehmann et al. characterize two new populations of neurons that undergo remodeling duringDrosophilametamorphosis. Beat-VaMneurons undergo drastic neurite pruning that is largely independent of ecdysone signaling and instead is driven by astrocytes. Beat-VaLneurons undergoAbd-Bmediated, caspase driven cell death in a segmentally restricted manner.