Quantitative Fluxomics of Circulating Metabolites

Mammalian organs are nourished by nutrients carried by the blood circulation. These nutrients originate from diet and internal stores, and can undergo various interconversions before their eventual use as tissue fuel. Here we develop isotope tracing, mass spectrometry, and mathematical analysis meth...

Full description

Saved in:
Bibliographic Details
Published inCell metabolism Vol. 32; no. 4; pp. 676 - 688.e4
Main Authors Hui, Sheng, Cowan, Alexis J., Zeng, Xianfeng, Yang, Lifeng, TeSlaa, Tara, Li, Xiaoxuan, Bartman, Caroline, Zhang, Zhaoyue, Jang, Cholsoon, Wang, Lin, Lu, Wenyun, Rojas, Jennifer, Baur, Joseph, Rabinowitz, Joshua D.
Format Journal Article
LanguageEnglish
Published United States Elsevier Inc 06.10.2020
Subjects
circulating metabolites
energy metabolism
in vivo flux quantification
isotope tracing
ketogenic diet
metabolic cycling
TCA cycle
metabolic cycling
circulating metabolites
ketogenic diet
TCA cycle
isotope tracing
in vivo flux quantification
energy metabolism
Online AccessGet full text

Cover

More Information
Summary:Mammalian organs are nourished by nutrients carried by the blood circulation. These nutrients originate from diet and internal stores, and can undergo various interconversions before their eventual use as tissue fuel. Here we develop isotope tracing, mass spectrometry, and mathematical analysis methods to determine the direct sources of circulating nutrients, their interconversion rates, and eventual tissue-specific contributions to TCA cycle metabolism. Experiments with fifteen nutrient tracers enabled extensive accounting for both circulatory metabolic cycles and tissue TCA inputs, across fed and fasted mice on either high-carbohydrate or ketogenic diet. We find that a majority of circulating carbon flux is carried by two major cycles: glucose-lactate and triglyceride-glycerol-fatty acid. Futile cycling through these pathways is prominent when dietary content of the associated nutrients is low, rendering internal metabolic activity robust to food choice. The presented in vivo flux quantification methods are broadly applicable to different physiological and disease states. [Display omitted] •Comprehensive isotope tracer studies reveal TCA substrate usage for 11 major organs•These data also reveal interconversion rates between circulating nutrients•Circulatory fluxes are similar across high-carbohydrate and ketogenic diet•Futile cycling helps render internal metabolic activity robust to food choice By infusing 15 different 13C-isotope tracers, Hui et al. quantify metabolic fluxes in mice on either high-carbohydrate or ketogenic diet. Results include interconversion fluxes between circulating metabolites and their contributions to the TCA cycle in 11 major organs. Rapid interconversion among circulating carbon carriers renders internal metabolic activity robust to diet.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
Equal contribution
AUTHOR CONTRIBUTIONS
S.H., A.J.C, and J.D.R. designed the study. S.H. performed most experiments and data analysis in mice fed on high carbohydrate diet. A.J.C. performed most experiments and data analysis in mice fed on ketogenic diet. X.Z. performed isotopic labeling measurement of acetate. L.Y. contributed to isotope tracing experiments in mice fed on ketogenic diet. X.Z., X.L., C.B., Z.Z, C.J. and L.W. contributed to isotope tracing experiments in mice fed on high carbohydrate diet. S.H. and J.D.R. performed the flux modeling. L.W. and W.L. contributed to LC-MS analysis of metabolites. A.J.C., J.R., and J.B. contributed to metabolic measurements of mice. S.H., A.J.C., and J.D.R. wrote the manuscript. All authors discussed the results and commented on the manuscript.
ISSN:1550-4131
1932-7420
DOI:10.1016/j.cmet.2020.07.013