PEPCK-M expression in mouse liver potentiates, not replaces, PEPCK-C mediated gluconeogenesis

Andrés Méndez-Lucas, João André Gonçalves Duarte, Nishanth E. Sunny, Santhosh Satapati, Tianteng He, Xiaorong Fu, Jordi Bermúdez, Shawn C. Burgess, Jose C. Perales

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Abstract

Background & Aims: Hepatic gluconeogenesis helps maintain systemic energy homeostasis by compensating for discontinuities in nutrient supply. Liver-specific deletion of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) abolishes gluconeogenesis from mitochondrial substrates, deregulates lipid metabolism and affects TCA cycle. While the mouse liver almost exclusively expresses PEPCK-C, humans equally present a mitochondrial isozyme (PEPCK-M). Despite clear relevance to human physiology, the role of PEPCK-M and its gluconeogenic potential remain unknown. Here, we test the significance of PEPCK-M in gluconeogenesis and TCA cycle function in liver-specific PEPCK-C knockout and WT mice. Methods: The effects of the overexpression of PEPCK-M were examined by a combination of tracer studies and molecular biology techniques. Partial PEPCK-C re-expression was used as a positive control. Metabolic fluxes were evaluated in isolated livers by NMR using 2H and 13C tracers. Gluconeogenic potential, together with metabolic profiling, was investigated in vivo and in primary hepatocytes. Results: PEPCK-M expression partially rescued defects in lipid metabolism, gluconeogenesis and TCA cycle function impaired by PEPCK-C deletion, while ∼10% re-expression of PEPCK-C normalized most parameters. When PEPCK-M was expressed in the presence of PEPCK-C, the mitochondrial isozyme amplified total gluconeogenic capacity, suggesting autonomous regulation of oxaloacetate to phosphoenolpyruvate fluxes by the individual isoforms. Conclusions: We conclude that PEPCK-M has gluconeogenic potential per se, and cooperates with PEPCK-C to adjust gluconeogenic/TCA flux to changes in substrate or energy availability, hinting at a role in the regulation of glucose and lipid metabolism in the human liver.

Original languageEnglish (US)
Pages (from-to)105-113
Number of pages9
JournalJournal of Hepatology
Volume59
Issue number1
DOIs
StatePublished - Jul 2013

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Gluconeogenesis
Liver
Lipid Metabolism
Phosphoenolpyruvate
Isoenzymes
Oxaloacetic Acid
Knockout Mice
Molecular Biology
Hepatocytes
Protein Isoforms
Homeostasis
Glucose
Food

ASJC Scopus subject areas

  • Hepatology

Cite this

Méndez-Lucas, A., Duarte, J. A. G., Sunny, N. E., Satapati, S., He, T., Fu, X., ... Perales, J. C. (2013). PEPCK-M expression in mouse liver potentiates, not replaces, PEPCK-C mediated gluconeogenesis. Journal of Hepatology, 59(1), 105-113. https://doi.org/10.1016/j.jhep.2013.02.020

PEPCK-M expression in mouse liver potentiates, not replaces, PEPCK-C mediated gluconeogenesis. / Méndez-Lucas, Andrés; Duarte, João André Gonçalves; Sunny, Nishanth E.; Satapati, Santhosh; He, Tianteng; Fu, Xiaorong; Bermúdez, Jordi; Burgess, Shawn C.; Perales, Jose C.

In: Journal of Hepatology, Vol. 59, No. 1, 07.2013, p. 105-113.

Research output: Contribution to journalArticle

Méndez-Lucas, A, Duarte, JAG, Sunny, NE, Satapati, S, He, T, Fu, X, Bermúdez, J, Burgess, SC & Perales, JC 2013, 'PEPCK-M expression in mouse liver potentiates, not replaces, PEPCK-C mediated gluconeogenesis', Journal of Hepatology, vol. 59, no. 1, pp. 105-113. https://doi.org/10.1016/j.jhep.2013.02.020
Méndez-Lucas, Andrés ; Duarte, João André Gonçalves ; Sunny, Nishanth E. ; Satapati, Santhosh ; He, Tianteng ; Fu, Xiaorong ; Bermúdez, Jordi ; Burgess, Shawn C. ; Perales, Jose C. / PEPCK-M expression in mouse liver potentiates, not replaces, PEPCK-C mediated gluconeogenesis. In: Journal of Hepatology. 2013 ; Vol. 59, No. 1. pp. 105-113.
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abstract = "Background & Aims: Hepatic gluconeogenesis helps maintain systemic energy homeostasis by compensating for discontinuities in nutrient supply. Liver-specific deletion of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) abolishes gluconeogenesis from mitochondrial substrates, deregulates lipid metabolism and affects TCA cycle. While the mouse liver almost exclusively expresses PEPCK-C, humans equally present a mitochondrial isozyme (PEPCK-M). Despite clear relevance to human physiology, the role of PEPCK-M and its gluconeogenic potential remain unknown. Here, we test the significance of PEPCK-M in gluconeogenesis and TCA cycle function in liver-specific PEPCK-C knockout and WT mice. Methods: The effects of the overexpression of PEPCK-M were examined by a combination of tracer studies and molecular biology techniques. Partial PEPCK-C re-expression was used as a positive control. Metabolic fluxes were evaluated in isolated livers by NMR using 2H and 13C tracers. Gluconeogenic potential, together with metabolic profiling, was investigated in vivo and in primary hepatocytes. Results: PEPCK-M expression partially rescued defects in lipid metabolism, gluconeogenesis and TCA cycle function impaired by PEPCK-C deletion, while ∼10{\%} re-expression of PEPCK-C normalized most parameters. When PEPCK-M was expressed in the presence of PEPCK-C, the mitochondrial isozyme amplified total gluconeogenic capacity, suggesting autonomous regulation of oxaloacetate to phosphoenolpyruvate fluxes by the individual isoforms. Conclusions: We conclude that PEPCK-M has gluconeogenic potential per se, and cooperates with PEPCK-C to adjust gluconeogenic/TCA flux to changes in substrate or energy availability, hinting at a role in the regulation of glucose and lipid metabolism in the human liver.",
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AU - Méndez-Lucas, Andrés

AU - Duarte, João André Gonçalves

AU - Sunny, Nishanth E.

AU - Satapati, Santhosh

AU - He, Tianteng

AU - Fu, Xiaorong

AU - Bermúdez, Jordi

AU - Burgess, Shawn C.

AU - Perales, Jose C.

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N2 - Background & Aims: Hepatic gluconeogenesis helps maintain systemic energy homeostasis by compensating for discontinuities in nutrient supply. Liver-specific deletion of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) abolishes gluconeogenesis from mitochondrial substrates, deregulates lipid metabolism and affects TCA cycle. While the mouse liver almost exclusively expresses PEPCK-C, humans equally present a mitochondrial isozyme (PEPCK-M). Despite clear relevance to human physiology, the role of PEPCK-M and its gluconeogenic potential remain unknown. Here, we test the significance of PEPCK-M in gluconeogenesis and TCA cycle function in liver-specific PEPCK-C knockout and WT mice. Methods: The effects of the overexpression of PEPCK-M were examined by a combination of tracer studies and molecular biology techniques. Partial PEPCK-C re-expression was used as a positive control. Metabolic fluxes were evaluated in isolated livers by NMR using 2H and 13C tracers. Gluconeogenic potential, together with metabolic profiling, was investigated in vivo and in primary hepatocytes. Results: PEPCK-M expression partially rescued defects in lipid metabolism, gluconeogenesis and TCA cycle function impaired by PEPCK-C deletion, while ∼10% re-expression of PEPCK-C normalized most parameters. When PEPCK-M was expressed in the presence of PEPCK-C, the mitochondrial isozyme amplified total gluconeogenic capacity, suggesting autonomous regulation of oxaloacetate to phosphoenolpyruvate fluxes by the individual isoforms. Conclusions: We conclude that PEPCK-M has gluconeogenic potential per se, and cooperates with PEPCK-C to adjust gluconeogenic/TCA flux to changes in substrate or energy availability, hinting at a role in the regulation of glucose and lipid metabolism in the human liver.

AB - Background & Aims: Hepatic gluconeogenesis helps maintain systemic energy homeostasis by compensating for discontinuities in nutrient supply. Liver-specific deletion of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) abolishes gluconeogenesis from mitochondrial substrates, deregulates lipid metabolism and affects TCA cycle. While the mouse liver almost exclusively expresses PEPCK-C, humans equally present a mitochondrial isozyme (PEPCK-M). Despite clear relevance to human physiology, the role of PEPCK-M and its gluconeogenic potential remain unknown. Here, we test the significance of PEPCK-M in gluconeogenesis and TCA cycle function in liver-specific PEPCK-C knockout and WT mice. Methods: The effects of the overexpression of PEPCK-M were examined by a combination of tracer studies and molecular biology techniques. Partial PEPCK-C re-expression was used as a positive control. Metabolic fluxes were evaluated in isolated livers by NMR using 2H and 13C tracers. Gluconeogenic potential, together with metabolic profiling, was investigated in vivo and in primary hepatocytes. Results: PEPCK-M expression partially rescued defects in lipid metabolism, gluconeogenesis and TCA cycle function impaired by PEPCK-C deletion, while ∼10% re-expression of PEPCK-C normalized most parameters. When PEPCK-M was expressed in the presence of PEPCK-C, the mitochondrial isozyme amplified total gluconeogenic capacity, suggesting autonomous regulation of oxaloacetate to phosphoenolpyruvate fluxes by the individual isoforms. Conclusions: We conclude that PEPCK-M has gluconeogenic potential per se, and cooperates with PEPCK-C to adjust gluconeogenic/TCA flux to changes in substrate or energy availability, hinting at a role in the regulation of glucose and lipid metabolism in the human liver.

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