Functional multi-organelle units control inflammatory lipid metabolism of macrophages. Functional multi-organelle units control inflammatory lipid metabolism of macrophages

Eukaryotic cells contain several membrane-separated organelles to compartmentalize distinct metabolic reactions. However, it has remained unclear how these organelle systems are coordinated, when cells adapt metabolic pathways to support their development, survival or effector functions. Here we present OrgaPlexing, a multispectral organelle imaging approach for the comprehensive mapping of six key metabolic organelles and their interactions. We use this analysis on macrophages, immune cells that undergo rapid metabolic switches upon sensing bacterial and inflammatory stimuli. Our results identify lipid droplets (LDs) as primary inflammatory responder organelle, which forms three- and four-way interactions with other organelles. While clusters with endoplasmic reticulum (ER) and mitochondria (M-ER-LD unit) help supply fatty acids for LD growth, the additional recruitment of peroxisomes (M-ER-P-LD unit) supports fatty acid efflux from LDs. Interference with individual components of these units has direct functional consequences for inflammatory lipid synthesis. Together, we show that macrophages form functional multi-organellar units (MOUs) to support metabolic adaptation, and provide an experimental strategy to identify organelle-metabolic signaling hubs. Overall design: bone marrow-derived mouse macrophages treated with LPS/IFNg for 0, 2, 6 and 24 hours

真核细胞含有多种膜包被细胞器，以区室化分隔不同的代谢反应。然而，当细胞调整代谢通路以支持自身发育、存活或效应功能时，这些细胞器系统如何协同调控，迄今仍未明确。本文报道了OrgaPlexing——一种多光谱细胞器成像方法，可对六种关键代谢细胞器及其相互作用进行全面绘图。我们将该分析方法应用于巨噬细胞——一类在感知细菌与炎症刺激时会发生快速代谢转换的免疫细胞。研究结果确认脂滴（lipid droplets, LDs）为主要的炎症应答细胞器，其可与其他细胞器形成三方及四方相互作用。其中，与内质网（endoplasmic reticulum, ER）和线粒体构成的M-ER-LD单元可为脂滴生长提供脂肪酸；而额外招募过氧化物酶体形成的M-ER-P-LD单元，则支持脂滴内脂肪酸的外排。干预这些复合物的单个组分，会对炎症性脂质合成产生直接的功能影响。综上，我们证明巨噬细胞可形成功能性多细胞器单元（multi-organellar units, MOUs）以支持代谢适应，并提供了一种可用于识别细胞器-代谢信号枢纽的实验策略。整体实验设计：采用脂多糖/干扰素γ（LPS/IFNg）处理骨髓来源小鼠巨噬细胞，处理时长分别为0、2、6及24小时。