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(13)C metabolic flux analysis in neurons utilizing a model that accounts for hexose phosphate recycling within the pentose phosphate pathway.
Neurochem Int. 2016 Feb; 93:26-39.NI

Abstract

Glycolysis, mitochondrial substrate oxidation, and the pentose phosphate pathway (PPP) are critical for neuronal bioenergetics and oxidation-reduction homeostasis, but quantitating their fluxes remains challenging, especially when processes such as hexose phosphate (i.e., glucose/fructose-6-phosphate) recycling in the PPP are considered. A hexose phosphate recycling model was developed which exploited the rates of glucose consumption, lactate production, and mitochondrial respiration to infer fluxes through the major glucose consuming pathways of adherent cerebellar granule neurons by replicating [(13)C]lactate labeling from metabolism of [1,2-(13)C2]glucose. Flux calculations were predicated on a steady-state system with reactions having known stoichiometries and carbon atom transitions. Non-oxidative PPP activity and consequent hexose phosphate recycling, as well as pyruvate production by cytoplasmic malic enzyme, were optimized by the model and found to account for 28 ± 2% and 7.7 ± 0.2% of hexose phosphate and pyruvate labeling, respectively. From the resulting fluxes, 52 ± 6% of glucose was metabolized by glycolysis, compared to 19 ± 2% by the combined oxidative/non-oxidative pentose cycle that allows for hexose phosphate recycling, and 29 ± 8% by the combined oxidative PPP/de novo nucleotide synthesis reactions. By extension, 62 ± 6% of glucose was converted to pyruvate, the metabolism of which resulted in 16 ± 1% of glucose oxidized by mitochondria and 46 ± 6% exported as lactate. The results indicate a surprisingly high proportion of glucose utilized by the pentose cycle and the reactions synthesizing nucleotides, and exported as lactate. While the in vitro conditions to which the neurons were exposed (high glucose, no lactate or other exogenous substrates) limit extrapolating these results to the in vivo state, the approach provides a means of assessing a number of metabolic fluxes within the context of hexose phosphate recycling in the PPP from a minimal set of measurements.

Authors+Show Affiliations

Department of Biology, Shoemaker Hall, University of Mississippi, University, MS 38677, USA. Electronic address: hmgebril@go.olemiss.edu.National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38677, USA. Electronic address: bavula@olemiss.edu.National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38677, USA. Electronic address: wangyh@olemiss.edu.Department of Biomedical Sciences and National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38677, USA. Electronic address: ikhan@olemiss.edu.Department of Biology, Shoemaker Hall, University of Mississippi, University, MS 38677, USA. Electronic address: jekabson@olemiss.edu.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

26723542

Citation

Gebril, Hoda M., et al. "(13)C Metabolic Flux Analysis in Neurons Utilizing a Model That Accounts for Hexose Phosphate Recycling Within the Pentose Phosphate Pathway." Neurochemistry International, vol. 93, 2016, pp. 26-39.
Gebril HM, Avula B, Wang YH, et al. (13)C metabolic flux analysis in neurons utilizing a model that accounts for hexose phosphate recycling within the pentose phosphate pathway. Neurochem Int. 2016;93:26-39.
Gebril, H. M., Avula, B., Wang, Y. H., Khan, I. A., & Jekabsons, M. B. (2016). (13)C metabolic flux analysis in neurons utilizing a model that accounts for hexose phosphate recycling within the pentose phosphate pathway. Neurochemistry International, 93, 26-39. https://doi.org/10.1016/j.neuint.2015.12.008
Gebril HM, et al. (13)C Metabolic Flux Analysis in Neurons Utilizing a Model That Accounts for Hexose Phosphate Recycling Within the Pentose Phosphate Pathway. Neurochem Int. 2016;93:26-39. PubMed PMID: 26723542.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - (13)C metabolic flux analysis in neurons utilizing a model that accounts for hexose phosphate recycling within the pentose phosphate pathway. AU - Gebril,Hoda M, AU - Avula,Bharathi, AU - Wang,Yan-Hong, AU - Khan,Ikhlas A, AU - Jekabsons,Mika B, Y1 - 2015/12/23/ PY - 2015/08/11/received PY - 2015/12/16/revised PY - 2015/12/18/accepted PY - 2016/1/3/entrez PY - 2016/1/3/pubmed PY - 2016/11/1/medline KW - Bioenergetics KW - Glycolysis KW - Malic enzyme KW - Mitochondria KW - Oxidative stress KW - Pentose phosphate pathway SP - 26 EP - 39 JF - Neurochemistry international JO - Neurochem. Int. VL - 93 N2 - Glycolysis, mitochondrial substrate oxidation, and the pentose phosphate pathway (PPP) are critical for neuronal bioenergetics and oxidation-reduction homeostasis, but quantitating their fluxes remains challenging, especially when processes such as hexose phosphate (i.e., glucose/fructose-6-phosphate) recycling in the PPP are considered. A hexose phosphate recycling model was developed which exploited the rates of glucose consumption, lactate production, and mitochondrial respiration to infer fluxes through the major glucose consuming pathways of adherent cerebellar granule neurons by replicating [(13)C]lactate labeling from metabolism of [1,2-(13)C2]glucose. Flux calculations were predicated on a steady-state system with reactions having known stoichiometries and carbon atom transitions. Non-oxidative PPP activity and consequent hexose phosphate recycling, as well as pyruvate production by cytoplasmic malic enzyme, were optimized by the model and found to account for 28 ± 2% and 7.7 ± 0.2% of hexose phosphate and pyruvate labeling, respectively. From the resulting fluxes, 52 ± 6% of glucose was metabolized by glycolysis, compared to 19 ± 2% by the combined oxidative/non-oxidative pentose cycle that allows for hexose phosphate recycling, and 29 ± 8% by the combined oxidative PPP/de novo nucleotide synthesis reactions. By extension, 62 ± 6% of glucose was converted to pyruvate, the metabolism of which resulted in 16 ± 1% of glucose oxidized by mitochondria and 46 ± 6% exported as lactate. The results indicate a surprisingly high proportion of glucose utilized by the pentose cycle and the reactions synthesizing nucleotides, and exported as lactate. While the in vitro conditions to which the neurons were exposed (high glucose, no lactate or other exogenous substrates) limit extrapolating these results to the in vivo state, the approach provides a means of assessing a number of metabolic fluxes within the context of hexose phosphate recycling in the PPP from a minimal set of measurements. SN - 1872-9754 UR - https://www.unboundmedicine.com/medline/citation/26723542/_13_C_metabolic_flux_analysis_in_neurons_utilizing_a_model_that_accounts_for_hexose_phosphate_recycling_within_the_pentose_phosphate_pathway_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0197-0186(15)30077-2 DB - PRIME DP - Unbound Medicine ER -