Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland.
Department of Biology, University of Fribourg, Fribourg, Switzerland.
Nat Cell Biol. 2022 Jun;24(6):996-1004. doi: 10.1038/s41556-022-00917-9. Epub 2022 Jun 2.
The distinct activities of organelles depend on the proper function of their membranes. Coordinated membrane biogenesis of different organelles necessitates lipid transport from their site of synthesis to their destination. Several factors have been proposed to participate in lipid distribution, but despite its basic importance, in vivo evidence linking the absence of putative transport pathways to specific transport defects remains scarce. A reason for this scarcity is the near absence of in vivo lipid trafficking assays. Here we introduce a versatile method named METALIC (Mass tagging-Enabled TrAcking of Lipids In Cells) to track interorganelle lipid flux inside cells. In this strategy, two enzymes, one directed to a 'donor' and the other to an 'acceptor' organelle, add two distinct mass tags to lipids. Mass-spectrometry-based detection of lipids bearing the two mass tags is then used to quantify exchange between the two organelles. By applying this approach, we show that the ERMES and Vps13-Mcp1 complexes have transport activity in vivo, and unravel their relative contributions to endoplasmic reticulum-mitochondria lipid exchange.
细胞器的独特活动依赖于其膜的正常功能。不同细胞器的协调膜生物发生需要脂质从其合成部位运输到目的地。已经提出了几种参与脂质分布的因素，但尽管其具有基本重要性，但将假定的运输途径的缺失与特定的运输缺陷联系起来的体内证据仍然很少。造成这种稀缺性的一个原因是体内脂质转运测定几乎不存在。在这里，我们引入了一种名为 METALIC（Mass tagging-Enabled TrAcking of Lipids In Cells）的通用方法，用于跟踪细胞内细胞器间的脂质通量。在这种策略中，两种酶，一种定向于“供体”细胞器，另一种定向于“受体”细胞器，将两个不同的质量标签添加到脂质上。然后，基于质谱的检测带有这两个质量标签的脂质，用于定量两个细胞器之间的交换。通过应用这种方法，我们表明 ERMES 和 Vps13-Mcp1 复合物在体内具有运输活性，并揭示了它们对内质网-线粒体脂质交换的相对贡献。
