TY - JOUR
T1 - Integrating Extracellular Flux Measurements and Genome-Scale Modeling Reveals Differences between Brown and White Adipocytes
AU - Ramirez, Alfred K.
AU - Lynes, Matthew D.
AU - Shamsi, Farnaz
AU - Xue, Ruidan
AU - Tseng, Yu Hua
AU - Kahn, C. Ronald
AU - Kasif, Simon
AU - Dreyfuss, Jonathan M.
N1 - Funding Information:
The authors would like to thank Katia Oleinik for high-performance computing technical assistance; Mark Crovella for suggested analyses; Marcia Haigis and Elma Zaganjor for the Nova instrument; Jens Nielsen for providing iAdipocytes1850; Neil Swainston for clarifications on Recon 2.2; Jonathan Fritzemeier for help with the Sybil package; and the Joslin Diabetes Center Media Core, supported by P30DK036836 (to Joslin’s Diabetes Research Center). A.K.R. was supported by NIH grant T32 DK007260-37 . This work was supported in part by NIH grants R01DK082659 (to C.R.K.), R01DK077097 and R01DK102898 (to Y.-H.T.), and P30DK036836 (to Joslin’s Diabetes Research Center). M.D.L. was supported by NIH grants T32DK007260 , F32DK102320 , and K01DK111714 .
Publisher Copyright:
© 2017 The Authors
PY - 2017/12/12
Y1 - 2017/12/12
N2 - White adipocytes are specialized for energy storage, whereas brown adipocytes are specialized for energy expenditure. Explicating this difference can help identify therapeutic targets for obesity. A common tool to assess metabolic differences between such cells is the Seahorse Extracellular Flux (XF) Analyzer, which measures oxygen consumption and media acidification in the presence of different substrates and perturbagens. Here, we integrate the Analyzer's metabolic profile from human white and brown adipocytes with a genome-scale metabolic model to predict flux differences across the metabolic map. Predictions matched experimental data for the metabolite 4-aminobutyrate, the protein ABAT, and the fluxes for glucose, glutamine, and palmitate. We also uncovered a difference in how adipocytes dispose of nitrogenous waste, with brown adipocytes secreting less ammonia and more urea than white adipocytes. Thus, the method and software we developed allow for broader metabolic phenotyping and provide a distinct approach to uncovering metabolic differences. Ramirez et al. integrate extracellular flux measurements with a human metabolic model to infer flux differences between brown (energy-burning) and white (energy-storing) adipocytes. Differences are experimentally validated. Brown adipocytes dispose of nitrogenous waste differently than white adipocytes. This method can be applied to any tissue/cell assayed with extracellular analyzers.
AB - White adipocytes are specialized for energy storage, whereas brown adipocytes are specialized for energy expenditure. Explicating this difference can help identify therapeutic targets for obesity. A common tool to assess metabolic differences between such cells is the Seahorse Extracellular Flux (XF) Analyzer, which measures oxygen consumption and media acidification in the presence of different substrates and perturbagens. Here, we integrate the Analyzer's metabolic profile from human white and brown adipocytes with a genome-scale metabolic model to predict flux differences across the metabolic map. Predictions matched experimental data for the metabolite 4-aminobutyrate, the protein ABAT, and the fluxes for glucose, glutamine, and palmitate. We also uncovered a difference in how adipocytes dispose of nitrogenous waste, with brown adipocytes secreting less ammonia and more urea than white adipocytes. Thus, the method and software we developed allow for broader metabolic phenotyping and provide a distinct approach to uncovering metabolic differences. Ramirez et al. integrate extracellular flux measurements with a human metabolic model to infer flux differences between brown (energy-burning) and white (energy-storing) adipocytes. Differences are experimentally validated. Brown adipocytes dispose of nitrogenous waste differently than white adipocytes. This method can be applied to any tissue/cell assayed with extracellular analyzers.
KW - brown adipose tissue
KW - extracellular flux analysis
KW - flux balance analysis
KW - metabolic flux analysis
KW - white adipose tissue
KW - Ammonia/metabolism
KW - Humans
KW - Homeostasis
KW - Palmitic Acid/metabolism
KW - Adipocytes, Brown/cytology
KW - Glutamine/metabolism
KW - Glucose/metabolism
KW - 4-Aminobutyrate Transaminase/metabolism
KW - Energy Metabolism/genetics
KW - Metabolome/genetics
KW - Organ Specificity
KW - Oxygen Consumption/genetics
KW - Metabolic Networks and Pathways/genetics
KW - Urea/metabolism
KW - gamma-Aminobutyric Acid/metabolism
KW - Adipocytes, White/cytology
KW - Software
KW - Primary Cell Culture
KW - Genome, Human
KW - Cell Line, Transformed
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U2 - 10.1016/j.celrep.2017.11.065
DO - 10.1016/j.celrep.2017.11.065
M3 - Article
C2 - 29241534
AN - SCOPUS:85037824789
SN - 2211-1247
VL - 21
SP - 3040
EP - 3048
JO - Cell Reports
JF - Cell Reports
IS - 11
ER -