Metabolic Flux Distribution during Defatting of Steatotic Human Hepatoma (HepG2) Cells

Metabolites

Gabriel Yarmush¹  Lucas Santos¹  Joshua Yarmush¹  Srivathsan Koundinyan¹  Mubasher Saleem¹  Nir I. Nativ¹  Rene S. Schloss¹  Martin L. Yarmush¹  Timothy J. Maguire¹  Francois Berthiaume¹ 

[1]Department of Biomedical Engineering, Rutgers University, Piscataway, NJ 08854, USA

关键词: fatty liver;    steatosis;    defatting;    beta-oxidation;    mass balances;    liver transplantation;    hepatocytes;   

DOI  :  10.3390/metabo6010001

来源: mdpi

【 摘 要 】

Methods that rapidly decrease fat in steatotic hepatocytes may be helpful to recover severely fatty livers for transplantation. Defatting kinetics are highly dependent upon the extracellular medium composition; however, the pathways involved are poorly understood. Steatosis was induced in human hepatoma cells (HepG2) by exposure to high levels of free fatty acids, followed by defatting using plain medium containing no fatty acids, or medium supplemented with a cocktail of defatting agents previously described before. We measured the levels of 28 extracellular metabolites and intracellular triglyceride, and fed the data into a steady-state mass balance model to estimate strictly intracellular fluxes. We found that during defatting, triglyceride content decreased, while beta-oxidation, the tricarboxylic acid cycle, and the urea cycle increased. These fluxes were augmented by defatting agents, and even more so by hyperoxic conditions. In all defatting conditions, the rate of extracellular glucose uptake/release was very small compared to the internal supply from glycogenolysis, and glycolysis remained highly active. Thus, in steatotic HepG2 cells, glycolysis and fatty acid oxidation may co-exist. Together, these pathways generate reducing equivalents that are supplied to mitochondrial oxidative phosphorylation.

【 授权许可】

CC BY   
© 2016 by the authors; licensee MDPI, Basel, Switzerland.