Chretien 2017 bioRxiv
|Chretien D, Benit P, Ha HH, Keipert S, El-Khoury R, Chang YT, Jastroch M, Jacobs H, Rustin P, Rak M (2017) Mitochondria are physiologically maintained at close to 50 C. bioRxiv doi: https://doi.org/10.1101/133223 .|
Abstract: In warm-blooded species, heat released as a by-product of metabolism ensures stable internal temperature throughout the organism, despite varying environmental conditions. Mitochondria are major actors in this thermogenic process. The energy released by the oxidation of respiratory substrates drives ATP synthesis and metabolite transport, with a variable proportion released as heat. Using a temperature-sensitive fluorescent probe targeted to mitochondria, we measured mitochondrial temperature in situ under different physiological conditions. At a constant external temperature of 38 C, mitochondria were more than 10 C warmer when the respiratory chain was fully functional, both in HEK cells and primary skin fibroblasts. This differential was abolished by respiratory inhibitors or in cells lacking mitochondrial DNA, but enhanced by expressing thermogenic enzymes such as the alternative oxidase or the uncoupling protein UCP1. The activity of various RC enzymes was maximal at, or slightly above, 50 C. Our study prompts a re-examination of the literature on mitochondria, taking account of the inferred high temperature.
Labels: MiParea: Respiration
Tissue;cell: HEK Preparation: Permeabilized cells
Regulation: Temperature Coupling state: OXPHOS Pathway: Gp