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Redox state and altered pyruvate metabolism contribute to a dose-dependent metformin-induced lactate production of human myotubes.

ABSTRACT: Metformin-induced glycolysis and lactate production can lead to acidosis as a life-threatening side effect, but slight increases in blood lactate levels in a physiological range were also reported in metformin-treated patients. However, how metformin increases systemic lactate concentrations is only partly understood. Because human skeletal muscle has a high capacity to produce lactate, the aim was to elucidate the dose-dependent regulation of metformin-induced lactate production and the potential contribution of skeletal muscle to blood lactate levels under metformin treatment. This was examined by using metformin treatment (16-776 μM) of primary human myotubes and by 17 days of metformin treatment in humans. As from 78 µM, metformin induced lactate production and secretion and glucose consumption. Investigating the cellular redox state by mitochondrial respirometry, we found metformin to inhibit the respiratory chain complex I (776 µM, P < 0.01) along with decreasing the [NAD⁺]:[NADH] ratio (776 µM, P < 0.001). RNA sequencing and phospho-immunoblot data indicate inhibition of pyruvate oxidation mediated through phosphorylation of the pyruvate dehydrogenase (PDH) complex (39 µM, P < 0.01). On the other hand, in human skeletal muscle, phosphorylation of PDH was not altered by metformin. Nonetheless, blood lactate levels were increased under metformin treatment (P < 0.05). In conclusion, the findings suggest that metformin-induced inhibition of pyruvate oxidation combined with altered cellular redox state shifts the equilibrium of the lactate dehydrogenase (LDH) reaction leading to a dose-dependent lactate production in primary human myotubes.NEW & NOTEWORTHY Metformin shifts the equilibrium of lactate dehydrogenase (LDH) reaction by low dose-induced phosphorylation of pyruvate dehydrogenase (PDH) resulting in inhibition of pyruvate oxidation and high dose-induced increase in NADH, which explains the dose-dependent lactate production of differentiated human skeletal muscle cells.

SUBMITTER: Maurer J

PROVIDER: S-EPMC10635655 | biostudies-literature | 2023 Oct

REPOSITORIES: biostudies-literature

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Redox state and altered pyruvate metabolism contribute to a dose-dependent metformin-induced lactate production of human myotubes.

Maurer Jennifer J Zhao Xinjie X Irmler Martin M Gudiksen Anders A Pilmark Nanna S NS Li Qi Q Goj Thomas T Beckers Johannes J Hrabě de Angelis Martin M Birkenfeld Andreas L AL Peter Andreas A Lehmann Rainer R Pilegaard Henriette H Karstoft Kristian K Xu Guowang G Weigert Cora C

American journal of physiology. Cell physiology 20230911 4

Metformin-induced glycolysis and lactate production can lead to acidosis as a life-threatening side effect, but slight increases in blood lactate levels in a physiological range were also reported in metformin-treated patients. However, how metformin increases systemic lactate concentrations is only partly understood. Because human skeletal muscle has a high capacity to produce lactate, the aim was to elucidate the dose-dependent regulation of metformin-induced lactate production and the potenti ...[more]

PMID: 37694284

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Project description:In order to obtain a global view of energy metabolism pathways of the sulfate-reducer Desulfovibrio vulgaris Hildenborough and the proteins involved therein whole-genome microarrays were used to compare the transcriptional response of cells grown with hydrogen/sulfate, pyruvate/sulfate, lactate/thiosulfate, and pyruvate with limiting sulfate, relative to growth in standard lactate/sulfate condition. Growth with hydrogen/sulfate showed the largest number of differently expressed genes and the largest changes in expression levels. The most up-regulated energy metabolism genes were those coding for the periplasmic [NiFeSe] hydrogenase, followed by the Ech hydrogenase, and the most down-regulated were genes coding for the Coo hydrogenase. The results point to the involvement of formate cycling and the ethanol pathway during growth on hydrogen, whereas there is evidence for CO cycling during growth on lactate and pyruvate, but not on H2. Growth with thiosulfate showed the hallmarks of a reduced energy status of the cells with down regulation of the ATP synthase and the Qmo and Dsr complexes., whereas growth with pyruvate showed the smallest differences but an increased role for the Ech hydrogenase.that in this case functions in reverse from the case of growth with H2. The multiple periplasmic hydrogenases and formate dehydrogenases, do not display the same regulation pattern showing that their metabolic roles are not totally interchangeable. This result together with the observation that several genes coding for proteins that have not been biochemically characterised were considerably affected in this study, reveals a more complex energy metabolism than previously considered and provides guidance for further studies. Keywords: Growth protocol Desulfovibrio vulgaris from our laboratory culture collection was cultured at 37°C with pyruvate as the only substrate (without sulfate as the electron acceptor) to mid-log phase. Cultures were also cultivated similarly in Lactate-Sulfate medium to mid-log phase. Gene expression profiles of cultures grown under pyruvate fermentation were compared with those of the cultures grown via sulfate reduction. Total RNA was harvested from four replicate cultures for microarray analysis. RNA extraction, purification, and labeling were performed independently on each cell sample.Two samples of each total RNA preparation were labeled, one with Cy3-dUTP and another with Cy5-dUTP for microarray hybridization.

Dataset Information

Redox state and altered pyruvate metabolism contribute to a dose-dependent metformin-induced lactate production of human myotubes.

Publications

Redox state and altered pyruvate metabolism contribute to a dose-dependent metformin-induced lactate production of human myotubes.

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