Pyruvate dehydrogenase phosphatase
About: Pyruvate dehydrogenase phosphatase is a research topic. Over the lifetime, 3534 publications have been published within this topic receiving 128529 citations. The topic is also known as: PDH & PDP.
Papers published on a yearly basis
TL;DR: A hypoxia-induced metabolic switch that shunts glucose metabolites from the mitochondria to glycolysis to maintain ATP production and to prevent toxic ROS production is revealed.
Abstract: Activation of glycolytic genes by HIF-1 is considered critical for metabolic adaptation to hypoxia through increased conversion of glucose to pyruvate and subsequently to lactate. We found that HIF-1 also actively suppresses metabolism through the tricarboxylic acid cycle (TCA) by directly trans-activating the gene encoding pyruvate dehydrogenase kinase 1 (PDK1). PDK1 inactivates the TCA cycle enzyme, pyruvate dehydrogenase (PDH), which converts pyruvate to acetyl-CoA. Forced PDK1 expression in hypoxic HIF-1alpha null cells increases ATP levels, attenuates hypoxic ROS generation, and rescues these cells from hypoxia-induced apoptosis. These studies reveal a hypoxia-induced metabolic switch that shunts glucose metabolites from the mitochondria to glycolysis to maintain ATP production and to prevent toxic ROS production.
TL;DR: The significance of this pathway in animal tissues, its physiological control and the relative importance of the direct oxidative and glycolytic routes of carbohydrate metabolism are still, however, chiefly matters of conjecture.
Abstract: Renewed interest in the direct oxidative pathway of glucose 6-phosphate metabolism during the last few years has revealed that this pathway is by no means restricted to erythrocytes, yeast and microorganisms. The triphosphopyridine-nucleotide(TPN)-specific glucose 6-phosphate and 6-phosphogluconate dehydrogenases are also widely distributed in mammalian tissues (Dickens & Glock, 1950, 1951; Horecker & Smyrniotis, 1951), in a variety of lower plants and animals (Cohen, 1950) and also in higher plants (Conn & Vennesland, 1951; Gibbs, 1952). The significance of this pathway in animal tissues, its physiological control and the relative importance of the direct oxidative and glycolytic routes of carbohydrate metabolism are still, however, chiefly matters of conjecture. An essential preliminary step to such an investigation is to devise a satisfactory procedure for the assay of glucose 6-phosphate and 6-phosphogluconate dehydrogenases in animal tissues and it was with this object in view that the present work was undertaken.
TL;DR: The results indicate that expression of this phosphotyrosine-binding form of pyruvate kinase is critical for rapid growth in cancer cells and Diverts glucose metabolites from energy production to anabolic processes when cells are stimulated by certain growth factors.
Abstract: Growth factors stimulate cells to take up excess nutrients and to use them for anabolic processes. The biochemical mechanism by which this is accomplished is not fully understood but it is initiated by phosphorylation of signalling proteins on tyrosine residues. Using a novel proteomic screen for phosphotyrosine-binding proteins, we have made the observation that an enzyme involved in glycolysis, the human M2 (fetal) isoform of pyruvate kinase (PKM2), binds directly and selectively to tyrosine-phosphorylated peptides. We show that binding of phosphotyrosine peptides to PKM2 results in release of the allosteric activator fructose-1,6-bisphosphate, leading to inhibition of PKM2 enzymatic activity. We also provide evidence that this regulation of PKM2 by phosphotyrosine signalling diverts glucose metabolites from energy production to anabolic processes when cells are stimulated by certain growth factors. Collectively, our results indicate that expression of this phosphotyrosine-binding form of pyruvate kinase is critical for rapid growth in cancer cells.
TL;DR: The homologous ABI1 and ABI2 phosphatases appear to assume partially redundant functions in ABA signaling, which may provide a mechanism to maintain informational homeostasis.
Abstract: Abscisic acid (ABA) mediates seed maturation and adaptive responses to environmental stress. In Arabidopsis, the ABA-INSENSITIVE1 (ABI1) protein phosphatase 2C is required for proper ABA responsiveness both in seeds and in vegetative tissues. To determine whether the lack of recessive alleles at the corresponding locus could be explained by the existence of redundant genes, we initiated a search for ABI1 homologs. One such homolog turned out to be the ABI2 locus, whose abi2-1 mutation was previously known to decrease ABA sensitivity. Whereas abi1-1 is (semi)dominant, abi2-1 has been described as recessive and maternally controlled at the germination stage. Unexpectedly, the sequence of the abi2-1 mutation showed that it converts Gly-168 to Asp, which is precisely the same amino acid substitution found in abi1-1 and at the coincidental position within the ABI1 phosphatase domain (Gly-180 to Asp). In vitro assays and functional complementation studies in yeast confirmed that the ABI2 protein is an active protein phosphatase 2C and that the abi2-1 mutation reduced phosphatase activity as well as affinity to Mg2+. Although a number of differences between the two mutants in adaptive responses to stress have been reported, quantitative comparisons of other major phenotypes showed that the effects of both abi1-1 and abi2-1 on these processes are nearly indistinguishable. Thus, the homologous ABI1 and ABI2 phosphatases appear to assume partially redundant functions in ABA signaling, which may provide a mechanism to maintain informational homeostasis.
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