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Showing papers on "Pyruvate dehydrogenase kinase published in 2016"


Journal ArticleDOI
TL;DR: It is demonstrated that PGK1 acts as a protein kinase in coordinating glycolysis and the tricarboxylic acid (TCA) cycle, which is instrumental in cancer metabolism and tumorigenesis.

278 citations


Journal ArticleDOI
TL;DR: It is shown that HIF-1α-PDK1-mediated metabolic changes occur in mild hypoxia, where mitochondrial cytochrome c oxidase activity is unimpaired, suggesting a mode of glycolytic reprogramming.
Abstract: In severely hypoxic condition, HIF-1α-mediated induction of Pdk1 was found to regulate glucose oxidation by preventing the entry of pyruvate into the tricarboxylic cycle. Monocyte-derived macrophages, however, encounter a gradual decrease in oxygen availability during its migration process in inflammatory areas. Here we show that HIF-1α-PDK1-mediated metabolic changes occur in mild hypoxia, where mitochondrial cytochrome c oxidase activity is unimpaired, suggesting a mode of glycolytic reprogramming. In primary macrophages, PKM2, a glycolytic enzyme responsible for glycolytic ATP synthesis localizes in filopodia and lammelipodia, where ATP is rapidly consumed during actin remodelling processes. Remarkably, inhibition of glycolytic reprogramming with dichloroacetate significantly impairs macrophage migration in vitro and in vivo. Furthermore, inhibition of the macrophage HIF-1α-PDK1 axis suppresses systemic inflammation, suggesting a potential therapeutic approach for regulating inflammatory processes. Our findings thus demonstrate that adaptive responses in glucose metabolism contribute to macrophage migratory activity.

218 citations


Journal ArticleDOI
TL;DR: Stable isotope-assisted metabolomics techniques are applied and it is demonstrated that pyruvate oxidation is maintained in mature pro-inflammatory macrophages and that the PDH flux is an important node for M(LPS) macrophage activation.

179 citations


Journal ArticleDOI
TL;DR: Cancer cells exhibit an altered metabolism which is characterized by a preference for aerobic glycolysis more than mitochondrial oxidation of pyruvate, suggesting that these metabolic changes may be due, in part, to an attenuated mitochondrial function which results from the inhibition of the pyruVate dehydrogenase complex (PDC).
Abstract: Cancer cells exhibit an altered metabolism which is characterized by a preference for aerobic glycolysis more than mitochondrial oxidation of pyruvate. This provides anabolic support and selective growth advantage for cancer cells. Recently, a new concept has arisen suggesting that these metabolic changes may be due, in part, to an attenuated mitochondrial function which results from the inhibition of the pyruvate dehydrogenase complex (PDC). This mitochondrial complex links glycolysis to the Krebs cycle and the current understanding of its regulation involves the cyclic phosphorylation and dephosphorylation by specific pyruvate dehydrogenase kinases (PDKs) and pyruvate dehydrogenase phosphatases (PDPs).

156 citations


Journal ArticleDOI
TL;DR: 1α,25(OH)2D3 regulates mitochondrial function, dynamics, and enzyme function, which is likely to influence muscle strength and vitamin D deficiency and chronic renal failure in skeletal muscle cells.

147 citations



Journal ArticleDOI
TL;DR: Under fasting conditions, when hepatic gluconeogenesis is stimulated, pyruvate recycling is relatively low in liver compared with VMito flux and that liver metabolism, in particular pyruVate cycling, is sensitive to propionate making it an unsuitable tracer to assess hepatic glycolytic, gluconeogenic, and mitochondrial metabolism in vivo.

63 citations


Journal ArticleDOI
TL;DR: The present review describes some of the original work of Eric Newsholme, its relevance to metabolic homoeostasis and disease and application to present state-of-the-art studies, which generate substantial amounts of data that are extremely difficult to interpret without a fundamental understanding of regulatory principles.
Abstract: The importance of metabolic pathways for life and the nature of participating reactions have challenged physiologists and biochemists for over a hundred years. Eric Arthur Newsholme contributed many original hypotheses and concepts to the field of metabolic regulation, demonstrating that metabolic pathways have a fundamental thermodynamic structure and that near identical regulatory mechanisms exist in multiple species across the animal kingdom. His work at Oxford University from the 1970s to 1990s was groundbreaking and led to better understanding of development and demise across the lifespan as well as the basis of metabolic disruption responsible for the development of obesity, diabetes and many other conditions. In the present review we describe some of the original work of Eric Newsholme, its relevance to metabolic homoeostasis and disease and application to present state-of-the-art studies, which generate substantial amounts of data that are extremely difficult to interpret without a fundamental understanding of regulatory principles. Eric's work is a classical example of how one can unravel very complex problems by considering regulation from a cell, tissue and whole body perspective, thus bringing together metabolic biochemistry, physiology and pathophysiology, opening new avenues that now drive discovery decades thereafter. * ACC, : acetyl-CoA carboxylase; AMPK, : AMP-activated protein kinase; CaMKK, : calmodulin-dependent protein kinase kinase; GLUT, : glucose transporter; GDH, : glutamate dehydrogenase; GLS, : glutaminase; GS, : glutamine synthetase; HIF, : hypoxia-inducible factor; HK, : hexokinase; LKB1, : liver kinase B1; mTOR, : mammalian target of rapamycin; mTORC1, : mTOR complex 1; PDHK, : pyruvate dehydrogenase kinase; PFK, : phosphofructokinase; SIRT4, : sirtuin 4; SLC, : solute carrier; TAK, : transforming growth factor-beta-activating kinase; TCA, : tricarboxylic acid

63 citations


Journal ArticleDOI
TL;DR: In this article, metabolic changes in a well-characterized cell model of familial ALS, the motor neuronal NSC-34 line stably expressing human wild-type Cu/Zn superoxide dismutase (wtSOD1) or mutant G93A (G93ASOD1), were examined.
Abstract: Defects in energy metabolism are potential pathogenic mechanisms in amyotrophic lateral sclerosis (ALS), a rapidly fatal disease with no cure. The mechanisms through which this occurs remain elusive and their understanding may prove therapeutically useful. We used metabolomics and stable isotope tracers to examine metabolic changes in a well-characterized cell model of familial ALS, the motor neuronal NSC-34 line stably expressing human wild-type Cu/Zn superoxide dismutase (wtSOD1) or mutant G93A (G93ASOD1). Our findings indicate that wt and G93ASOD1 expression both enhanced glucose metabolism under serum deprivation. However, in wtSOD1 cells, this phenotype increased supply of amino acids for protein and glutathione synthesis, while in G93ASOD1 cells it was associated with death, aerobic glycolysis, and a broad dysregulation of amino acid homeostasis. Aerobic glycolysis was mainly due to induction of pyruvate dehydrogenase kinase 1. Our study thus provides novel insight into the role of deranged energy metabolism as a cause of poor adaptation to stress and a promoter of neural cell damage in the presence of mutant SOD1. Furthermore, the metabolic alterations we report may help explain why mitochondrial dysfunction and impairment of the endoplasmic reticulum stress response are frequently seen in ALS.

59 citations


Journal ArticleDOI
TL;DR: Dichloroacetate significantly sensitized resistant HNC cells to cisplatin in vitro and in vivo, and activated downstream mitochondrial apoptotic signaling, leading to the death of chemoresistant cancer cells.

59 citations


Journal ArticleDOI
TL;DR: It is concluded that MCT-1 is part of a core Wnt signaling gene program for glycolysis in colon cancer and that modulation of this program could play an important role in shaping sensitivity to drugs that target cancer metabolism.
Abstract: There is increasing evidence that oncogenic Wnt signaling directs metabolic reprogramming of cancer cells to favor aerobic glycolysis or Warburg metabolism. In colon cancer, this reprogramming is due to direct regulation of pyruvate dehydrogenase kinase 1 (PDK1) gene transcription. Additional metabolism genes are sensitive to Wnt signaling and exhibit correlative expression with PDK1. Whether these genes are also regulated at the transcriptional level, and therefore a part of a core metabolic gene program targeted by oncogenic WNT signaling, is not known. Here, we identify monocarboxylate transporter 1 (MCT-1; encoded by SLC16A1) as a direct target gene supporting Wnt-driven Warburg metabolism. We identify and validate Wnt response elements (WREs) in the proximal SLC16A1 promoter and show that they mediate sensitivity to Wnt inhibition via dominant-negative LEF-1 (dnLEF-1) expression and the small molecule Wnt inhibitor XAV939. We also show that WREs function in an independent and additive manner with c-Myc, the only other known oncogenic regulator of SLC16A1 transcription. MCT-1 can export lactate, the byproduct of Warburg metabolism, and it is the essential transporter of pyruvate as well as a glycolysis-targeting cancer drug, 3-bromopyruvate (3-BP). Using sulforhodamine B (SRB) assays to follow cell proliferation, we tested a panel of colon cancer cell lines for sensitivity to 3-BP. We observe that all cell lines are highly sensitive and that reduction of Wnt signaling by XAV939 treatment does not synergize with 3-BP, but instead is protective and promotes rapid recovery. We conclude that MCT-1 is part of a core Wnt signaling gene program for glycolysis in colon cancer and that modulation of this program could play an important role in shaping sensitivity to drugs that target cancer metabolism.

Journal ArticleDOI
TL;DR: The results suggest that diabetic rats countervail ROS stress through increasing pentose pathway, and reprogram the energy metabolic pathway from glycolysis into lipid oxidation in order to compensate the ATP requirement of the body, which causes insulin resistance.

Journal ArticleDOI
TL;DR: DCA can reverse the mitochondrial suppression of ccRCC and decrease HIF transcriptional activity, bypassing its constitutive expression and its previous clinical use in humans makes it an attractive candidate for translation toccRCC patients.

Journal ArticleDOI
TL;DR: It is concluded that a reduction of mtDNA copy number and decrease of respiratory function of mitochondria in RCC might be compensated for by an increase of enzymes and factors that are involved in the upregulation of glycolysis to confer RCC more invasive and a drug-resistant phenotype in vitro.
Abstract: We investigated the role of mitochondrial DNA (mtDNA) copy number alteration in human renal cell carcinoma (RCC). The mtDNA copy numbers of paired cancer and non-cancer parts from five resected RCC kidneys after radical nephrectomy were determined by quantitative polymerase chain reaction (Q-PCR). An RCC cell line, 786-O, was infected by lentiviral particles to knock down mitochondrial transcriptional factor A (TFAM). Null target (NT) and TFAM-knockdown (TFAM-KD) represented the control and knockdown 786-O clones, respectively. Protein or mRNA expression levels of TFAM; mtDNA-encoded NADH dehydrogenase subunit 1 (ND1), ND6 and cytochrome c oxidase subunit 2 (COX-2); nuclear DNA (nDNA)-encoded succinate dehydrogenase subunit A (SDHA); v-akt murine thymoma viral oncogene homolog 1 gene (AKT)-encoded AKT and v-myc myelocytomatosis viral oncogene homolog gene (c-MYC)-encoded MYC; glycolytic enzymes including hexokinase II (HK-II), glucose 6-phosphate isomerase (GPI), phosphofructokinase (PFK), and lactate dehydrogenase subunit A (LDHA); and hypoxia-inducible factors the HIF-1α and HIF-2α, pyruvate dehydrogenase kinase 1 (PDK1), and pyruvate dehydrogenase E1 component α subunit (PDHA1) were analyzed by Western blot or Q-PCR. Bioenergetic parameters of cellular metabolism, basal mitochondrial oxygen consumption rate (mOCRB) and basal extracellular acidification rate (ECARB), were measured by a Seahorse XFe-24 analyzer. Cell invasiveness was evaluated by a trans-well migration assay and vimentin expression. Doxorubicin was used as a chemotherapeutic agent. The results showed a decrease of mtDNA copy numbers in resected RCC tissues (p = 0.043). The TFAM-KD clone expressed lower mtDNA copy number (p = 0.034), lower mRNA levels of TFAM (p = 0.008), ND1 (p = 0.007), and ND6 (p = 0.017), and lower protein levels of TFAM and COX-2 than did the NT clone. By contrast, the protein levels of HIF-2α, HK-II, PFK, LDHA, AKT, MYC and vimentin; trans-well migration activity (p = 0.007); and drug resistance to doxorubicin (p = 0.008) of the TFAM-KD clone were significantly higher than those of the NT clone. Bioenergetically, the TFAM-KD clone expressed lower mOCRB (p = 0.009) but higher ECARB (p = 0.037) than did the NT clone. We conclude that a reduction of mtDNA copy number and decrease of respiratory function of mitochondria in RCC might be compensated for by an increase of enzymes and factors that are involved in the upregulation of glycolysis to confer RCC more invasive and a drug-resistant phenotype in vitro.

Journal ArticleDOI
TL;DR: It is reported that pyruvate dehydrogenase kinases (PDK2 and PDK4), key regulatory enzymes in glucose metabolism, mediate glycolytic metabolic shift in the DRG leading to painful diabetic neuropathy.

Journal ArticleDOI
TL;DR: It is shown that rat skeletal muscle mitochondria can produce superoxide/H2O2 at high rates when given 2-oxoadipate, and Regulation by ADP and ATP of H 2O2 production driven by 2- oxoadipates was very different from that driven by2-oxoglutarate, suggesting that site AF of the 2-Oxoadipat dehydrogenase complex is a new source of superoxide /H2 O2 associated with the NADH is

Journal ArticleDOI
TL;DR: Exogenous putrescine reversed the salt stress and increased gene expression and, in turn, the key enzymes involved in the glycolysis pathway and Krebs cycle, which significantly increased the amounts of organic acids and pyruvate produced, promoting the release of more energy currency (ATP and ADP).
Abstract: The effects of exogenous putrescine (8 mmol L−1) on the carbohydrate content, glycolytic metabolism, citric acid cycle intermediates, key enzyme activities and their corresponding gene expression in cucumber (cucumis sativus L. cv. Jingyou NO.4) subjected to salt stress (75 mmol L−1 NaCl) in solution culture was studied. Phosphofructokinase (PFK), pyruvate kinase (PK) and phosphoenolpyruvate pyruvate kinase (PEPC) activities were significantly decreased in leaves when exposed to salt stress. NaCl stress caused the PFK and PK gene expression and the content of pyruvate to significantly decrease, while PEPC gene expression increased. Salt stress also significantly reduced isocitrate dehydrogenase, malate dehydrogenase and succinate dehydrogenase and their levels of transcription, causing decreases in the citric acid, succinic acid and malic acid content in leaves. Exogenous putrescine reversed the salt stress and increased gene expression and, in turn, the key enzymes involved in the glycolysis pathway and Krebs cycle, which significantly increased the amounts of organic acids and pyruvate produced, promoting the release of more energy currency (ATP and ADP). These results suggest that Put effectively participate glycolysis pathway and Krebs cycle, reducing the excessive accumulation of carbohydrates in the leaves, and providing more material and energy for the defense salt-induced injury, thus enhances cucumber seedling to salt stress tolerance.

Journal ArticleDOI
06 Jul 2016-Diabetes
TL;DR: It is reported that increasing hepatic PDC activity by inhibition of PDK2 ameliorates hepatic steatosis and insulin sensitivity by regulating TCA cycle anaplerosis and ketogenesis, and the findings suggestPDK2 is a potential therapeutic target for nonalcoholic fatty liver disease.
Abstract: Hepatic steatosis is associated with increased insulin resistance and tricarboxylic acid (TCA) cycle flux, but decreased ketogenesis and pyruvate dehydrogenase complex (PDC) flux. This study examined whether hepatic PDC activation by inhibition of pyruvate dehydrogenase kinase 2 (PDK2) ameliorates these metabolic abnormalities. Wild-type mice fed a high-fat diet exhibited hepatic steatosis, insulin resistance, and increased levels of pyruvate, TCA cycle intermediates, and malonyl-CoA but reduced ketogenesis and PDC activity due to PDK2 induction. Hepatic PDC activation by PDK2 inhibition attenuated hepatic steatosis, improved hepatic insulin sensitivity, reduced hepatic glucose production, increased capacity for β-oxidation and ketogenesis, and decreased the capacity for lipogenesis. These results were attributed to altered enzymatic capacities and a reduction in TCA anaplerosis that limited the availability of oxaloacetate for the TCA cycle, which promoted ketogenesis. The current study reports that increasing hepatic PDC activity by inhibition of PDK2 ameliorates hepatic steatosis and insulin sensitivity by regulating TCA cycle anaplerosis and ketogenesis. The findings suggest PDK2 is a potential therapeutic target for nonalcoholic fatty liver disease.

Journal ArticleDOI
TL;DR: Mammalian photoreceptors contain dimeric and tetrameric PKM2 and LDH-A, consistent with the ability to switch between energy production and biosynthesis like a proliferating tissue, possibly due to demands of opsin synthesis.
Abstract: Robert J. Casson, John P. M. Wood, Guoge Han, Thaksaon Kittipassorn, Daniel J. Peet, and Glyn Chidlow

Journal ArticleDOI
TL;DR: This review covers the recent advances that implicate the PDK-lactic acid axis as a novel linker of metabolism and diverse neuropathophysiologies and explores the possibilities of employing it and its downstream mediators as putative future therapeutic strategies aimed at prevention or treatment of neurological disorders.

Journal ArticleDOI
TL;DR: It is reported that in MM MIR126 initiates a metabolic program leading to high autophagic flux and HIF1α stabilization, incompatible with tumor progression of MM, showing that increased autophagy has a protective role in MM.
Abstract: Autophagy favors both cell survival and cancer suppression, and increasing evidence reveals that microRNAs (MIRs) regulate autophagy. Previously we reported that MIR126 is downregulated in malignant mesothelioma (MM). Therefore, we investigated the role of MIR126 in the regulation of cell metabolism and autophagy in MM models. We report that MIR126 induces autophagic flux in MM cells by downregulating insulin receptor substrate-1 (IRS1) and disrupting the IRS1 signaling pathway. This was specific to MM cells, and was not observed in non-malignant cells of mesothelial origin or in MM cells expressing MIR126-insensitive IRS1 transcript. The MIR126 effect on autophagy in MM cells was recapitulated by IRS1 silencing, and antagonized by IRS1 overexpression or antisense MIR126 treatment. The MIR126-induced loss of IRS1 suppressed glucose uptake, leading to energy deprivation and AMPK-dependent phosphorylation of ULK1. In addition, MIR126 stimulated lipid droplet accumulation in a hypoxia-inducible factor-1α (HIF1α)-dependent manner. MIR126 also reduced pyruvate dehydrogenase kinase (PDK) and acetyl-CoA-citrate lyase (ACL) expression, leading to the accumulation of cytosolic citrate and paradoxical inhibition of pyruvate dehydrogenase (PDH) activity. Simultaneous pharmacological and genetic intervention with PDK and ACL activity phenocopied the effects of MIR126. This suggests that in MM MIR126 initiates a metabolic program leading to high autophagic flux and HIF1α stabilization, incompatible with tumor progression of MM. Consistently, MIR126-expressing MM cells injected into immunocompromised mice failed to progress beyond the initial stage of tumor formation, showing that increased autophagy has a protective role in MM.

Journal ArticleDOI
TL;DR: Testing which metabolic fate of pyruvate contributed to the appearance of HP [13C]bicarbonate by the liver in rats after 21 h of fasting compared to rats with free access to food revealed 13C NMR analysis of glutamate isolated from the liver of rats revealed that flux from injected pyruVate through pyruviate dehydrogenase was dominant under fed conditions whereas flux through pyRuvate carboxylase dominated under fasted conditions.
Abstract: The source of hyperpolarized (HP) [(13)C]bicarbonate in the liver during metabolism of HP [1-(13)C]pyruvate is uncertain and likely changes with physiology. Multiple processes including decarboxylation through pyruvate dehydrogenase or pyruvate carboxylase followed by subsequent decarboxylation via phosphoenolpyruvate carboxykinase (gluconeogenesis) could play a role. Here we tested which metabolic fate of pyruvate contributed to the appearance of HP [(13)C]bicarbonate during metabolism of HP [1-(13)C]pyruvate by the liver in rats after 21 h of fasting compared to rats with free access to food. The (13)C NMR of HP [(13)C]bicarbonate was observed in the liver of fed rats, but not in fasted rats where pyruvate carboxylation and gluconeogenesis was active. To further explore the relative fluxes through pyruvate carboxylase versus pyruvate dehydrogenase in the liver under typical conditions of hyperpolarization studies, separate parallel experiments were performed with rats given non-hyperpolarized [2,3-(13)C]pyruvate. (13)C NMR analysis of glutamate isolated from the liver of rats revealed that flux from injected pyruvate through pyruvate dehydrogenase was dominant under fed conditions whereas flux through pyruvate carboxylase dominated under fasted conditions. The NMR signal of HP [(13)C]bicarbonate does not parallel pyruvate carboxylase activity followed by subsequent decarboxylation reaction leading to glucose production. In the liver of healthy well-fed rats, the appearance of HP [(13)C]bicarbonate exclusively reflects decarboxylation of HP [1-(13)C]pyruvate via pyruvate dehydrogenase.

11 Mar 2016
TL;DR: In this paper, pyruvate dehydrogenase kinases (PDK2 and PDK4), key regulatory enzymes in glucose metabolism, mediate glycolytic metabolic shift in the dorsal root ganglion (DRG), leading to painful diabetic neuropathy.
Abstract: The dorsal root ganglion (DRG) is a highly vulnerable site in diabetic neuropathy. Under diabetic conditions, the DRG is subjected to tissue ischemia or lower ambient oxygen tension that leads to aberrant metabolic functions. Metabolic dysfunctions have been documented to play a crucial role in the pathogenesis of diverse pain hypersensitivities. However, the contribution of diabetes-induced metabolic dysfunctions in the DRG to the pathogenesis of painful diabetic neuropathy remains ill-explored. In this study, we report that pyruvate dehydrogenase kinases (PDK2 and PDK4), key regulatory enzymes in glucose metabolism, mediate glycolytic metabolic shift in the DRG leading to painful diabetic neuropathy. Streptozotocin-induced diabetes substantially enhanced the expression and activity of the PDKs in the DRG, and the genetic ablation of Pdk2 and Pdk4 attenuated the hyperglycemia-induced pain hypersensitivity. Mechanistically, Pdk2/4 deficiency inhibited the diabetes-induced lactate surge, expression of pain-related ion channels, activation of satellite glial cells, and infiltration of macrophages in the DRG, in addition to reducing central sensitization and neuroinflammation hallmarks in the spinal cord, which probably accounts for the attenuated pain hypersensitivity. Pdk2/4-deficient mice were partly resistant to the diabetes-induced loss of peripheral nerve structure and function. Furthermore, in the experiments using DRG neuron cultures, lactic acid treatment enhanced the expression of the ion channels and compromised cell viability. Finally, the pharmacological inhibition of DRG PDKs or lactic acid production substantially attenuated diabetes-induced pain hypersensitivity. Taken together, PDK2/4 induction and the subsequent lactate surge induce the metabolic shift in the diabetic DRG, thereby contributing to the pathogenesis of painful diabetic neuropathy.

Journal ArticleDOI
TL;DR: Overall, during normoxia when glucose is the only exogenous fuel, DCA elevates SR calcium, increases LVDP and contractility, and diminishes mitochondrial NADH, and Administering DCA with plasma levels of lactate and pyruvate mitigates the drop in mitochondrial NADh and prevents PVCs.
Abstract: Dichloroacetate (DCA) and pyruvate activate pyruvate dehydrogenase (PDH), a key enzyme that modulates glucose oxidation and mitochondrial NADH production. Both compounds improve recovery after ischemia in isolated hearts. However, the action of DCA and pyruvate in normoxic myocardium is incompletely understood. We measured the effect of DCA and pyruvate on contraction, mitochondrial redox state, and intracellular calcium cycling in isolated rat hearts during normoxic perfusion. Normalized epicardial NADH fluorescence (nNADH) and left ventricular developed pressure (LVDP) were measured before and after administering DCA (5 mM) or pyruvate (5 mM). Optical mapping of Rhod-2AM was used to measure cytosolic calcium kinetics. DCA maximally activated PDH, increasing the ratio of active to total PDH from 0.48 ± 0.03 to 1.03 ± 0.03. Pyruvate sub-maximally activated PDH to a ratio of 0.75 ± 0.02. DCA and pyruvate increased LVDP. When glucose was the only exogenous fuel, pyruvate increased nNADH by 21.4 ± 2.9 % while DCA reduced nNADH by 21.4 ± 6.1 % and elevated the incidence of premature ventricular contractions (PVCs). When lactate, pyruvate, and glucose were provided together as exogenous fuels, nNADH increased with DCA, indicating that PDH activation with glucose as the only exogenous fuel depletes PDH substrate. Calcium transient time-to-peak was shortened by DCA and pyruvate and SR calcium re-uptake was 30 % longer. DCA and pyruvate increased SR calcium load in myocyte monolayers. Overall, during normoxia when glucose is the only exogenous fuel, DCA elevates SR calcium, increases LVDP and contractility, and diminishes mitochondrial NADH. Administering DCA with plasma levels of lactate and pyruvate mitigates the drop in mitochondrial NADH and prevents PVCs.

Journal ArticleDOI
TL;DR: These studies suggest that the MPC plays an important and ancestral role in insulin-secreting cells in mediating glucose sensing, regulating insulin secretion, and controlling systemic glycemia.
Abstract: Objective Transport of pyruvate into the mitochondrial matrix by the Mitochondrial Pyruvate Carrier (MPC) is an important and rate-limiting step in its metabolism. In pancreatic β-cells, mitochondrial pyruvate metabolism is thought to be important for glucose sensing and glucose-stimulated insulin secretion.

Journal ArticleDOI
TL;DR: For the first time, DCA derived inhibitors that preferentially bind to the adenosine triphosphate (ATP) pocket of PDK isoform 1 (PDK1) are successfully developed.
Abstract: Pyruvate dehydrogenase kinases (PDKs) have recently emerged as an attractive target for cancer therapy. Herein, we prepared a series of compounds derived from dichloroacetate (DCA) which inhibited cancer cells proliferation. For the first time, we have successfully developed DCA derived inhibitors that preferentially bind to the adenosine triphosphate (ATP) pocket of PDK isoform 1 (PDK1).

Journal ArticleDOI
TL;DR: It is identified that pykA encodes an active pyruvate kinase that is allosterically activated by glucose 6-phosphate (Glc-6-P) and adenosine monophosphates (AMP).

Journal ArticleDOI
TL;DR: Evidence is provided that connects the inflammatory mediator OSM to a hypoxia-like metabolic phenotype in the human hepatocyte cell line PH5CH, and since PDK1 is overexpressed in several cancers, it might provide a causal link between chronic inflammation and malignant cellular transformation.
Abstract: Hypoxia and inflammation have been identified as hallmarks of cancer. A majority of hepatocellular carcinomas are preceded by hepatitis B- or C-related chronic infections suggesting that liver cancer development is promoted by an inflammatory microenvironment. The inflammatory cytokine oncostatin M (OSM) was shown to induce the expression of hypoxia-inducible factor-1 α (HIF-1 α) under normoxic conditions in hepatocytes and hepatoma cells. HIF-1 α is known to orchestrate the expression of numerous genes, many of which code for metabolic enzymes that play key roles in the adaptation of cellular metabolism to low oxygen tension. Here, we show that OSM-induced upregulation of HIF-1 α reprograms cellular metabolism in three clones of the human hepatocyte cell line PH5CH (PH5CH1, PH5CH7, and PH5CH8) towards a hypoxia-like metabolic phenotype but has no significant effect on cellular metabolism of HepG2 and JHH-4 hepatoma cells. Although we observed only minor changes in glucose uptake and lactate secretion in PH5CH8 upon OSM treatment, we identified more pronounced changes in intracellular fluxes based on stable isotope labeling experiments. In particular, glucose oxidation in the tricarboxylic acid (TCA) cycle is reduced through pyruvate dehydrogenase kinase 1 (PDK1)-mediated inhibition of the pyruvate dehydrogenase complex, thereby reducing the oxidative TCA cycle flux. As a result of the impaired mitochondrial glucose and glutamine oxidation, the reductive isocitrate dehydrogenase flux was increased. We provide evidence that connects the inflammatory mediator OSM to a hypoxia-like metabolic phenotype. In the human hepatocyte cell line PH5CH, OSM-mediated upregulation of HIF-1 α and PDK1 can induce hypoxia-like metabolic changes, although to a lesser extent than hypoxia itself. Since PDK1 is overexpressed in several cancers, it might provide a causal link between chronic inflammation and malignant cellular transformation.

Journal ArticleDOI
TL;DR: The correlation between the expression and/or activity or redox enzymes and biofilm-formation activities suggests that these are possible therapeutic targets to erradicate S. epidermidis.
Abstract: Staphylococcus epidermidis has become a major health hazard. It is necessary to study its metabolism and hopefully uncover therapeutic targets. Cultivating S. epidermidis at increasing oxygen concentration [O2] enhanced growth, while inhibiting biofilm formation. Respiratory oxidoreductases were differentially expressed, probably to prevent reactive oxygen species formation. Under aerobiosis, S. epidermidis expressed high oxidoreductase activities, including glycerol-3-phosphate dehydrogenase, pyruvate dehydrogenase, ethanol dehydrogenase and succinate dehydrogenase, as well as cytochromes bo and aa3; while little tendency to form biofilms was observed. Under microaerobiosis, pyruvate dehydrogenase and ethanol dehydrogenase decreased while glycerol-3-phosphate dehydrogenase and succinate dehydrogenase nearly disappeared; cytochrome bo was present; anaerobic nitrate reductase activity was observed; biofilm formation increased slightly. Under anaerobiosis, biofilms grew; low ethanol dehydrogenase, pyruvate dehydrogenase and cytochrome bo were still present; nitrate dehydrogenase was the main terminal electron acceptor. KCN inhibited the aerobic respiratory chain and increased biofilm formation. In contrast, methylamine inhibited both nitrate reductase and biofilm formation. The correlation between the expression and/or activity or redox enzymes and biofilm-formation activities suggests that these are possible therapeutic targets to erradicate S. epidermidis.

Journal ArticleDOI
TL;DR: Two novel natural coumarins compounds from the ZINC database were found binding to PDKs with favorable interaction energy and predicted to be non-toxic and valuable information of PDK-coumarins binding mechanisms in PDK inhibitor-based drug discovery is provided.
Abstract: Pyruvate dehydrogenase kinases (PDKs) are key enzymes in glucose metabolism, negatively regulating pyruvate dehyrogenase complex (PDC) activity through phosphorylation. Inhibiting PDKs could upregulate PDC activity and drive cells into more aerobic metabolism. Therefore, PDKs are potential targets for metabolism related diseases, such as cancers and diabetes. In this study, a series of computer-aided virtual screening techniques were utilized to discover potential inhibitors of PDKs. Structure-based screening using Libdock was carried out following by ADME (adsorption, distribution, metabolism, excretion) and toxicity prediction. Molecular docking was used to analyze the binding mechanism between these compounds and PDKs. Molecular dynamic simulation was utilized to confirm the stability of potential compound binding. From the computational results, two novel natural coumarins compounds (ZINC12296427 and ZINC12389251) from the ZINC database were found binding to PDKs with favorable interaction energy and predicted to be non-toxic. Our study provide valuable information of PDK-coumarins binding mechanisms in PDK inhibitor-based drug discovery.