Pyruvate kinase

About: Pyruvate kinase is a research topic. Over the lifetime, 5683 publications have been published within this topic receiving 180020 citations. The topic is also known as: ATP:pyruvate 2-O-phosphotransferase & phosphoenolpyruvate kinase.

The Fungicide Phosphonate Disrupts the Phosphate-Starvation Response in Brassica nigra Seedlings

Abstract: The development of Brassica nigra seedlings over 20 d of growth was disrupted by the fungicide phosphonate (Phi) in a manner inversely correlated with nutritional inorganic phosphate (Pi) levels. The growth of Pi-sufficient (1.25 mM Pi) seedlings was suppressed when 10, but not 5, mM Phi was added to the nutrient medium. In contrast, the fresh weights and root:shoot ratios of Pi-limited (0.15 mM) seedlings were significantly reduced at 1.5 mM Phi, and they progressively declined to about 40% of control values as medium Phi concentration was increased to 10 mM. Intracellular Pi levels generally decreased in Phi-treated seedlings, and Phi accumulated in leaves and roots to levels up to 6- and 16-fold that of Pi in Pi-sufficient and Pi-limited plants, respectively. Extractable activities of the Pi-starvation-inducible enzymes phosphoenolpyruvate phosphatase and inorganic pyrophosphate-dependent phosphofructokinase were unaltered in Pi-sufficient seedlings grown on 5 or 10 mM Phi. However, when Pi-limited seedlings were grown on 1.5 to 10 mM Phi (a) the induction of phosphoenolpyruvate phosphatase and inorganic pyrophosphate-dependent phosphofructokinase activities by Pi limitation was reduced by 40 to 90%, whereas (b) soluble protein concentrations and the activities of the ATP-dependent phosphofructokinase and pyruvate kinase were unaffacted. It is concluded that Phi specifically interrupts processes involved in regulation of the Pi-starvation response in B. nigra.

Metabolic and Proliferative State of Vascular Adventitial Fibroblasts in Pulmonary Hypertension Is Regulated Through a MicroRNA-124/PTBP1 (Polypyrimidine Tract Binding Protein 1)/Pyruvate Kinase Muscle Axis

Abstract: Background: An emerging metabolic theory of pulmonary hypertension (PH) suggests that cellular and mitochondrial metabolic dysfunction underlies the pathology of this disease. We and others have previously demonstrated the existence of hyperproliferative, apoptosis-resistant, proinflammatory adventitial fibroblasts from human and bovine hypertensive pulmonary arterial walls (PH-Fibs) that exhibit constitutive reprogramming of glycolytic and mitochondrial metabolism, accompanied by an increased ratio of glucose catabolism through glycolysis versus the tricarboxylic acid cycle. However, the mechanisms responsible for these metabolic alterations in PH-Fibs remain unknown. We hypothesized that in PH-Fibs microRNA-124 (miR-124) regulates PTBP1 (polypyrimidine tract binding protein 1) expression to control alternative splicing of pyruvate kinase muscle (PKM) isoforms 1 and 2, resulting in an increased PKM2/PKM1 ratio, which promotes glycolysis and proliferation even in aerobic environments. Methods: Pulmonary adventitial fibroblasts were isolated from calves and humans with severe PH (PH-Fibs) and from normal subjects. PTBP1 gene knockdown was achieved via PTBP1-siRNA; restoration of miR-124 was performed with miR-124 mimic. TEPP-46 and shikonin were used to manipulate PKM2 glycolytic function. Histone deacetylase inhibitors were used to treat cells. Metabolic products were determined by mass spectrometry–based metabolomics analyses, and mitochondrial function was analyzed by confocal microscopy and spectrofluorometry. Results: We detected an increased PKM2/PKM1 ratio in PH-Fibs compared with normal subjects. PKM2 inhibition reversed the glycolytic status of PH-Fibs, decreased their cell proliferation, and attenuated macrophage interleukin-1β expression. Furthermore, normalizing the PKM2/PKM1 ratio in PH-Fibs by miR-124 overexpression or PTBP1 knockdown reversed the glycolytic phenotype (decreased the production of glycolytic intermediates and byproducts, ie, lactate), rescued mitochondrial reprogramming, and decreased cell proliferation. Pharmacological manipulation of PKM2 activity with TEPP-46 and shikonin or treatment with histone deacetylase inhibitors produced similar results. Conclusions: In PH, miR-124, through the alternative splicing factor PTBP1, regulates the PKM2/PKM1 ratio, the overall metabolic, proliferative, and inflammatory state of cells. This PH phenotype can be rescued with interventions at various levels of the metabolic cascade. These findings suggest a more integrated view of vascular cell metabolism, which may open unique therapeutic prospects in targeting the dynamic glycolytic and mitochondrial interactions and between mesenchymal inflammatory cells in PH.

Sodium dichloroacetate selectively targets cells with defects in the mitochondrial ETC.

Abstract: The "Warburg effect," also termed aerobic glycolysis, describes the increased reliance of cancer cells on glycolysis for ATP production, even in the presence of oxygen. Consequently, there is continued interest in inhibitors of glycolysis as cancer therapeutics. One example is dichloroacetate (DCA), a pyruvate mimetic that stimulates oxidative phosphorylation through inhibition of pyruvate dehydrogenase kinase. In this study, the mechanistic basis for DCA anti-cancer activity was re-evaluated in vitro using biochemical, cellular and proteomic approaches. Results demonstrated that DCA is relatively inactive (IC(50) ≥ 17 mM, 48 hr), induces apoptosis only at high concentrations (≥ 25 mM, 48 hr) and is not cancer cell selective. Subsequent 2D-PAGE proteomic analysis confirmed DCA-induced growth suppression without apoptosis induction. Furthermore, DCA depolarizes mitochondria and promotes reactive oxygen species (ROS) generation in all cell types. However, DCA was found to have selective activity against rho(0) cells [mitochondrial DNA (mtDNA) deficient] and to synergize with 2-deoxyglucose in complex IV deficient HCT116 p53(-/-) cells. DCA also synergized in vitro with cisplatin and topotecan, two antineoplastic agents known to damage mitochondrial DNA. These data suggest that in cells "hardwired" to selectively utilize glycolysis for ATP generation (e.g., through mtDNA mutations), the ability of DCA to force oxidative phosphorylation confers selective toxicity. In conclusion, although we provide a mechanism distinct from that reported previously, the ability of DCA to target cell lines with defects in the electron transport chain and to synergize with existing chemotherapeutics supports further preclinical development.