Real-Time Imaging of Mitochondrial ATP Dynamics Reveals the Metabolic Setting of Single Cells

Abstract

Summary: Reprogramming of metabolic pathways determines cell functions and fate. In our work, we have used organelle-targeted ATP biosensors to evaluate cellular metabolic settings with high resolution in real time. Our data indicate that mitochondria dynamically supply ATP for glucose phosphorylation in a variety of cancer cell types. This hexokinase-dependent process seems to be reversed upon the removal of glucose or other hexose sugars. Our data further verify that mitochondria in cancer cells have increased ATP consumption. Similar subcellular ATP fluxes occurred in young mouse embryonic fibroblasts (MEFs). However, pancreatic beta cells, senescent MEFs, and MEFs lacking mitofusin 2 displayed completely different mitochondrial ATP dynamics, indicative of increased oxidative phosphorylation. Our findings add perspective to the variability of the cellular bioenergetics and demonstrate that live cell imaging of mitochondrial ATP dynamics is a powerful tool to evaluate metabolic flexibility and heterogeneity at a single-cell level. : Depaoli et al. show that ATP levels, particularly within mitochondria, are affected in a highly dynamic manner by glucose depletion. Different cell types, including cancer cells, show specific mitochondrial ATP responses. These subcellular ATP signals are used to assess metabolic activity and flexibility at the single-cell level. Keywords: aerobic glycolysis, cancer cell metabolism, aging, ATP, bioenergetics, live cell imaging, mitochondria, mitofusin 2, Warburg effect, mitochondrial respiration