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 effect of HIF-1α on glucose metabolism, growth and apoptosis of pancreatic cancerous cells.

Abstract: Objectives: The aim of this study is to explore the possible role of HIF-1α in glucose metabolism, proliferation and apoptosis of pancreatic cancerous cells. Method: The pancreatic cancerous BxPC-3 cells were cultured in normoxia or hypoxia (3% O2), respectively. Cell proliferation was determined by MTT assay, apoptosis was determined by Annexin V/PI staining. Expression of Pyruvate dehydrogenase kinase (PDK1), Lactate dehydrogenase (LDHA), pyruvate kinase M2 (PKM2) and citrate synthase (CS) was determined by Western-blot and Real-time PCR. Results: Under hypoxia, the expression of HIF-1α and the lactate production were increased. The expression of glucose metabolic enzymes PDK1, LDHA, PKM2 was also increased compared with that under aerobic condition. Hypoxia treatment had little effect on expression of CS. Under hypoxia, knockdown of HIF-1α inhibited the production of lactate and the expression of PDK1, LDHA and PKM2. Knockdown of HIF-1α repressed the growth of pancreatic cancer BxPC-3 cells and induced apoptosis of the cells under hypoxia. Conclusion: Under hypoxia, the expression of HIF-1α is induced, leading to the increase of glycolysis in BxPC-3 cells possibly through upregulation of the enzymes related to glycolysis. HIF-1α knockdown can inhibit the prolife ratio and promote apoptosis of pancreatic cancerous BxPC-3 cells in vitro.

The role of pyruvate hub enzymes in supplying carbon precursors for fatty acid synthesis in photosynthetic microalgae.

Abstract: Photosynthetic microalgae are currently the focus of basic and applied research due to an ever-growing interest in renewable energy resources. This review discusses the role of carbon-unit supply for the production of acetyl-CoA, a direct precursor of fatty acid biosynthesis and the primary building block of the growing acyl chains for the purpose of triacylglycerol (TAG) production in photosynthetic microalgae under stressful conditions. It underscores the importance of intraplastidic acetyl-CoA generation for storage lipid accumulation. The main focus is placed on two enzymatic steps linking the central carbon metabolism and fatty acid synthesis, namely the reactions catalyzed by the plastidic isoform of pyruvate kinase and the chloroplastic pyruvate dehydrogenase complex. Alternative routes for plastidic acetyl-CoA synthesis are also reviewed. A separate section is devoted to recent advances in functional genomics studies related to fatty acid and TAG biosynthesis.

Phosphorus-31 NMR studies of maltose and glucose metabolism in Streptococcus lactis

Abstract: Streptococcus lactis ferments glucose in a homolactic fashion but a heterolactic fermentation pattern is observed when it is grown on maltose. Using in vivo phosphorus-31 and carbon-13 NMR studies of glucose-metabolizing cells we confirmed that fructosediphosphate (FDP) is the major glycolytic intermediate and that the production of lactate causes major changes both in the intra- and extracellular pH values. Starved cells contain mainly 3-phosphoglycerate (3-PGA) and some phosphoenolpyruvate (PEP). Metabolism of maltose also brings about major changes in pH, but it was unclear from the poorly resolved in vivo spectra if FDP was the main glycolytic intermediate present. This question was further studied by analyzing perchloric acid extracts by phosphorus-31 NMR. These studies showed that glucose-metabolizing cells have higher levels of FDP and lower levels of inorganic phosphate (P i) than maltose-metabolizing cells. 3-PGA always remained present in the latter cells suggesting that these exist in a semi-starved state which is probably the reason for their heterolactic fermentation pattern. In the course of these studies we also examined the effects of the inhibitors 2-deoxyglucose, fluoride and iodoacetate. We could demonstrate that by judicious choice of carbon sources and inhibitors one could completely reduce the intracellular P i pool. This suggests that one should be able to regulate the shift from heterolactic to homolactic fermentation, as P i is considered to be the most potent inhibitor of pyruvate kinase in these cells.

Carbohydrate metabolism by primary cultures of rabbit proximal tubules.

Abstract: Renal proximal tubular epithelia were used to assess the factors responsible for the induction of glycolysis in cultured cells. Primary cultures of rabbit proximal tubules, which achieved confluency at 6 days, exhibited hormonal responsiveness and brush-border characteristics typical of proximal tubular cells. Beginning at day 4, these cultured cells exhibited increased glycolytic metabolism reflected by enhanced glucose uptake and lactate production, along with parallel increases in activity of the glycolytic enzymes, pyruvate kinase and lactate dehydrogenase. The gluconeogenic enzymes, phosphoenolpyruvate carboxykinase (PEPCK) and fructose-1,6-bisphosphatase (FDP), were downregulated, and the cultured cells exhibited lower oxygen consumption rates than fresh tubules. Cells grown on a rocker, to mitigate hypoxia, exhibited a metabolic and enzymatic profile similar to cells grown under still conditions. ATP levels in cultured cells were higher than in fresh tubules. Furthermore, pyruvate kinase activity was higher in cells grown in media containing 0.5 as contrasted with 25 mM glucose. The enhanced glycolytic metabolism exhibited by cultured proximal tubular cells appears to be a characteristic of proliferation and is not a response to hypoxia, the Pasteur effect, or environmental glucose.