AMP-Activated Protein Kinase Links Neuronal Remodeling to Metabolic Control

神经元形态发生不仅涉及神经突生长等渐进性事件，还涉及神经突变性等退行性事件，称为神经元重塑或修剪。果蝇外周感觉神经元是研究修剪机制的一个非常合适的模型，它在变态开始时修剪它们的幼虫树突。这一过程是由蜕皮激素依赖性转录诱导的，涉及神经元细胞骨架的重塑，以允许神经突脱落和随后的变性。已知蜕皮激素对细胞生长和代谢也有很强的影响，但尚未评估代谢和修剪之间的联系。我们发现，两个AMP激活的蛋白激酶家族成员- Par-1/MARK和AMPK本身-是修剪所必需的。尽管Par-1是细胞骨架重塑所必需的，但我们的AMPK遗传数据表明，这种激酶将细胞代谢（翻译和能量代谢）与神经元重塑联系起来。在这里，我们建议系统地研究细胞代谢和神经元重塑之间的相互作用。为此，我们将（1）使用基于RNASeq和FRET的代谢物报告基因来描述早期蛹神经元的代谢转变;（2）在AMPK修剪缺陷修饰剂的遗传筛选中鉴定AMPK靶点。AMPK靶点将在激酶测定中进行生物化学确认。此外，我们已经确定了候选AMPK上游激酶和磷酸酶，我们将确认这些生化，我们将评估这些因素如何连接AMPK上游蜕皮激素的调节。我们的项目将为新陈代谢和神经元连接之间的相互作用提供重要的见解。

Neuronal morphogenesis does not only involve progressive events like neurite outgrowth, but also regressive events like neurite degeneration, known as neuronal remodeling, or pruning. A well-suited model to study pruning mechanisms are Drosophila peripheral sensory neurons, which prune their larval dendrites at the onset of metamorphosis. This process is induced by ecdysone-dependent transcription and involves remodeling of the neuronal cytoskeleton to allow for neurite abscission and subsequent degeneration. Ecdysone is known to have strong effects also on cell growth and metabolism, but links between metabolism and pruning have not been assessed. We found that two members of the AMP-activated protein kinase family - Par-1/MARK and AMPK itself - are required for pruning. Whereas Par-1 is required for cytoskeletal remodeling, our genetic data for AMPK show that this kinase links cellular metabolism (translation and energy metabolism) to neuronal remodeling. Here, we propose to systematically investigate the interplay between cellular metabolism and neuronal remodeling. To this end, we will (1) use RNASeq and FRET-based metabolite reporters to describe the metabolic transitions of early pupal neurons; and (2) identify AMPK targets in genetic screens for modifiers of the AMPK pruning defect. AMPK targets will be confirmed biochemically in kinase assays. Furthermore, we have identified candidate AMPK upstream kinases and phosphatases We will confirm these biochemically and we will assess how these factors link AMPK to upstream ecdysone hormonal regulation. Our project will provide important insights into the interplay between metabolism and neuronal connectivity.