Metabolic flux analysis of hepatocyte function in hormone- and amino acid-supplemented plasma

Christina Chan, François Berthiaume, Kyongbum Lee, Martin L. Yarmush

    Research output: Research - peer-reviewArticle

    • 44 Citations

    Abstract

    Understanding the metabolic and regulatory pathways of hepatocytes is important for biotechnological applications involving liver cells. Previous attempts to culture hepatocytes in plasma yielded poor functional results. Recently we reported that hormone (insulin and hydrocortisone) and amino acid supplementation reduces intracellular lipid accumulation and restores liver-specific function in hepatocytes exposed to heparinized human plasma. In the current study, we performed metabolic flux analysis (MFA) using a simplified metabolic network model of cultured hepatocytes to quantitively estimate the changes in lipid metabolism and relevant intracellular pathways in response to hormone and amino acid supplementation. The model accounts for the majority of central carbon and nitrogen metabolism, and assumes pseudo-steady-state with no metabolic futile cycles. We found that β-oxidation and tricarboxylic acid (TCA) cycle fluxes were upregulated by both hormone and amino acid supplementation, thus enhancing the rate of lipid oxidation. Concomitantly, hormone and amino acid supplementation increased gluconeogenic fluxes. This, together with an increased rate of glucose clearance, caused an increase in predicted glycogen synthesis. Urea synthesis was primarily derived from ammonia and aspartate generated through transamination reactions, while exogenous ammonia removal accounted for only 3-6% of the urea nitrogen. Amino acid supplementation increased the endogenous synthesis of oxaloacetate, and in turn that of aspartate, a necessary substrate for the urea cycle. These findings from MFA provide cues as to which genes/pathways relevant to fatty acid oxidation, urea production, and gluconeogenesis may be upregulated by plasma supplementation, and are consistent with current knowledge of hepatic amino acid metabolism, which provides further credence to this approach for evaluating the metabolic state of hepatocytes under various environmental conditions.

    LanguageEnglish (US)
    Pages1-15
    Number of pages15
    JournalMetabolic Engineering
    Volume5
    Issue number1
    DOIs
    StatePublished - Jan 2003

    Profile

    Hormones
    Fluxes
    Plasmas
    Amino Acids
    Hepatocytes
    Amino acids
    Metabolic Flux Analysis
    Urea
    Oxidation
    Liver
    Ammonia
    Metabolism
    Aspartic Acid
    Nitrogen
    Lipids
    Metabolic Networks and Pathways
    Plasma (human)
    Oxaloacetic Acid
    Glycogen
    Hydrocortisone

    ASJC Scopus subject areas

    • Biophysics
    • Bioengineering
    • Endocrinology, Diabetes and Metabolism

    Cite this

    Metabolic flux analysis of hepatocyte function in hormone- and amino acid-supplemented plasma. / Chan, Christina; Berthiaume, François; Lee, Kyongbum; Yarmush, Martin L.

    In: Metabolic Engineering, Vol. 5, No. 1, 01.2003, p. 1-15.

    Research output: Research - peer-reviewArticle

    Chan, Christina ; Berthiaume, François ; Lee, Kyongbum ; Yarmush, Martin L./ Metabolic flux analysis of hepatocyte function in hormone- and amino acid-supplemented plasma. In: Metabolic Engineering. 2003 ; Vol. 5, No. 1. pp. 1-15
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