A metabolic labelling-based lipid imaging technology establishes VPS13A as a phosphatidylethanolamine lipid transfer protein

Abstract

The ability to image specific lipid subtypes within cells can have a transformative impact on the study of lipid dynamics and trafficking mechanisms. Herein, we describe a technology for imaging phosphatidylethanolamine (PE) lipids in live mammalian cells that involved screening a library of ethanolamine derivatives to identify an azido compound that efficiently metabolically labels PE. Crucially, this probe evades the cellular methylation machinery specifically labelling PE without forming labelled methylated PE and phosphatidylcholine (PC) lipids. The administration of cyclooctyne dyes to cells metabolically labelled with this probe rendered azido PE lipids fluorescent via strain-promoted click chemistry, enabling imaging. We employed this technology to image PE in various cellular organelles, visualize PE externalization during apoptosis, and discover that the VPS13A protein transports PE from the endoplasmic reticulum to the mitochondria. This technology will facilitate addressing fundamental questions in PE biology and studying dysregulation of PE dynamics and trafficking in disease states.