title: Fructose Alters Intermediary Metabolism of Glucose in Human Adipocytes and Diverts Glucose to Serine Oxidation in the One-Carbon Cycle Energy Producing Pathway.
abstract: Increased consumption of sugar and fructose as sweeteners has resulted in the utilization of fructose as an alternative metabolic fuel that may compete with glucose and alter its metabolism. To explore this, human Simpson-Golabi-Behmel Syndrome (SGBS) preadipocytes were differentiated to adipocytes in the presence of 0, 1, 2.5, 5 or 10 mM of fructose added to a medium containing 5 mM of glucose representing the normal blood glucose concentration. Targeted tracer [1,2-13C2]-d-glucose fate association approach was employed to examine the influence of fructose on the intermediary metabolism of glucose. Increasing concentrations of fructose robustly increased the oxidation of [1,2-13C2]-d-glucose to 13CO2 (p < 0.000001). However, glucose-derived 13CO2 negatively correlated with 13C labeled glutamate, 13C palmitate, and M+1 labeled lactate. These are strong markers of limited tricarboxylic acid (TCA) cycle, fatty acid synthesis, pentose cycle fluxes, substrate turnover and NAD+/NADP+ or ATP production from glucose via complete oxidation, indicating diminished mitochondrial energy metabolism. Contrarily, a positive correlation was observed between glucose-derived 13CO2 formed and 13C oleate and doses of fructose which indicate the elongation and desaturation of palmitate to oleate for storage. Collectively, these results suggest that fructose preferentially drives glucose through serine oxidation glycine cleavage (SOGC pathway) one-carbon cycle for NAD+/NADP+ production that is utilized in fructose-induced lipogenesis and storage in adipocytes.
authors.affiliation: Biomarkers and Alternate Models branch, Division of Systems Biology, National Center for Toxicological Research, Jefferson, AR 72079, USA. vijayalakshmi.varma@fda.hhs.gov.
authors.forename: Vijayalakshmi
authors.initials: V
authors.lastname: Varma
authors.affiliation: SiDMAP LLC, Los Angeles, CA 90064, USA. lboros@sidmap.com.|Los Angeles Biomedical Research Institute (LABIOMED), Torrance, CA 90502, USA. lboros@sidmap.com.|Department of Pediatrics, Harbor-UCLA Medical Center, Torrance, CA 90502, USA. lboros@sidmap.com.
authors.forename: László G
authors.initials: LG
authors.lastname: Boros
authors.affiliation: Biomarkers and Alternate Models branch, Division of Systems Biology, National Center for Toxicological Research, Jefferson, AR 72079, USA. greg.nolen@fda.hhs.gov.
authors.forename: Greg T
authors.initials: GT
authors.lastname: Nolen
authors.affiliation: Division of Bioinformatics and Biostatistics, National Center for Toxicological Research, Jefferson, AR 72079, USA. ching-wei.chang@fda.hhs.gov.
authors.forename: Ching-Wei
authors.initials: CW
authors.lastname: Chang
authors.affiliation: Division of Pediatric Endocrinology and Diabetology, University of Ulm, Eythstr. 24, 89075 Ulm, Germany. martin.wabitsch@uniklinik-ulm.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Wabitsch
authors.affiliation: Biomarkers and Alternate Models branch, Division of Systems Biology, National Center for Toxicological Research, Jefferson, AR 72079, USA. richard.beger@fda.hhs.gov.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Beger
authors.affiliation: Current Address: Nestle Institute of Health Sciences, 1015 Lausanne, Switzerland. james.kaput@rd.nestle.com.
authors.forename: Jim
authors.initials: J
authors.lastname: Kaput
keywords: SOGC pathway; [1,2-13C2]-d-glucose; fructose; glucose; human adipocytes; targeted tracer fate association study (TTFAS)