Developmental neuronal remodeling is extensive and mechanistically diverse across the nervous system. We sought to identify Drosophila pupal neurons that underwent mechanistically new types of neuronal remodeling and describe remodeling Beat-VaM and Beat-VaL neurons. We show that Beat-VaM neurons produce highly branched neurites in the CNS during larval stages that undergo extensive local pruning. Surprisingly, although the ecdysone receptor (EcR) is essential for pruning in all other cell types studied, Beat-VaM neurons remodel their branches extensively despite cell autonomous blockade EcR or caspase signaling. Proper execution of local remodeling in Beat-VaM neurons instead depends on extrinsic signaling from astrocytes converging with intrinsic and less dominant EcR-regulated mechanisms. In contrast, Beat-VaL neurons undergo steroid hormone-dependent, apoptotic cell death, which we show relies on the segment-specific expression of the Hox gene Abd-B. Our work provides new cell types in which to study neuronal remodeling, highlights an important role for astrocytes in activating local pruning in Drosophila independent of steroid signaling, and defines a Hox gene-mediated mechanism for segment-specific cell elimination.

中文翻译：

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Beat-Va 神经元中的星形胶质细胞依赖性局部神经突修剪。


发育神经元重塑在整个神经系统中广泛且机制多样。我们试图识别在机制上经历新型神经元重塑的果蝇蛹神经元，并描述重塑 Beat-VaM 和 Beat-VaL 神经元。我们表明，Beat-VaM 神经元在幼虫阶段在经历广泛局部修剪的幼虫阶段在 CNS 中产生高度分支的神经突。令人惊讶的是，尽管蜕皮激素受体 （EcR） 对于所研究的所有其他细胞类型的修剪至关重要，但 Beat-VaM 神经元尽管细胞自主阻断 EcR 或 caspase 信号传导，但仍广泛地重塑了它们的分支。相反，在 Beat-VaM 神经元中正确执行局部重塑取决于星形胶质细胞的外源性信号转导与内在和不太显性的 EcR 调节机制会聚。相比之下，Beat-VaL 神经元经历类固醇激素依赖性凋亡细胞死亡，我们表明这依赖于 Hox 基因 Abd-B 的片段特异性表达。我们的工作为研究神经元重塑提供了新的细胞类型，强调了星形胶质细胞在独立于类固醇信号传导的果蝇局部修剪中的重要作用，并定义了节段特异性细胞消除的 Hox 基因介导的机制。