The effects of the interactions between amino acids on pyruvate kinase activity from the brain cortex of young rats

Feksa, Luciane Rosa; Cornelio, Andrea Renata; Dutra-Filho, Carlos Severo; Wyse, Ângela T. S.; Wajner, Moaçir; Wannmacher, Clóvis Milton Duval

doi:10.1016/j.ijdevneu.2005.06.002

Cited by 16 publications

(8 citation statements)

References 21 publications

(25 reference statements)

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“…GK27, PFK42, PK43, Na + /K + -ATPase44 activities were assayed as described previously. Hepatic glucose and pyruvate content were measured using assay kits (Su Zhou Keming Bioengineer Company, China) according to the manufacturer's instructions.…”

Section: Methodsmentioning

confidence: 99%

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1-deoxynojirimycin inhibits glucose absorption and accelerates glucose metabolism in streptozotocin-induced diabetic mice

et al. 2013

Sci Rep

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We investigated the role of 1-deoxynojirimycin (DNJ) on glucose absorption and metabolism in normal and diabetic mice. Oral and intravenous glucose tolerance tests and labeled 13C6-glucose uptake assays suggested that DNJ inhibited intestinal glucose absorption in intestine. We also showed that DNJ down-regulated intestinal SGLT1, Na+/K+-ATP and GLUT2 mRNA and protein expression. Pretreatment with DNJ (50 mg/kg) increased the activity, mRNA and protein levels of hepatic glycolysis enzymes (GK, PFK, PK, PDE1) and decreased the expression of gluconeogenesis enzymes (PEPCK, G-6-Pase). Assays of protein expression in hepatic cells and in vitro tests with purified enzymes indicated that the increased activity of glucose glycolysis enzymes was resulted from the relative increase in protein expression, rather than from direct enzyme activation. These results suggest that DNJ inhibits intestinal glucose absorption and accelerates hepatic glucose metabolism by directly regulating the expression of proteins involved in glucose transport systems, glycolysis and gluconeogenesis enzymes.

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Section: Methodsmentioning

confidence: 99%

“…Enzyme activities were measured according to previous methods274243. DNJ at final concentrations of 0, 40, 80, 160, 320, 640, 1280 μg/mL was incubated with the GK (PFK, PK) enzymes for 15 min before each assay.…”

Section: Methodsmentioning

confidence: 99%

1-deoxynojirimycin inhibits glucose absorption and accelerates glucose metabolism in streptozotocin-induced diabetic mice

et al. 2013

Sci Rep

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“…GK [21], PFK [22], PK [23], PEPCK [24] and G-6-Pase [25] activities were assayed as described previously.…”

Section: Methodsmentioning

confidence: 99%

“…Their activities were measured as described in previous studies [21]–[23]. DPM at final concentrations of 0, 1.25, 2.5, 5, 10, 20, 40 µg/ml were incubated with GK, PFK, PK enzymes for 15 min before the assays.…”

Section: Methodsmentioning

confidence: 99%

Cooperative Anti-Diabetic Effects of Deoxynojirimycin-Polysaccharide by Inhibiting Glucose Absorption and Modulating Glucose Metabolism in Streptozotocin-Induced Diabetic Mice

et al. 2013

PLoS ONE

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We had previously shown that deoxynojirimycin-polysaccharide mixture (DPM) not only decreased blood glucose but also reversed the damage to pancreatic β-cells in diabetic mice, and that the anti-hyperglycemic efficacy of this combination was better than that of 1-deoxynojirimycin (DNJ) or polysachharide alone. However, the mechanisms behind these effects were not fully understood. The present study aimed to evaluate the therapeutic effects of DPM on streptozotocin (STZ)-induced diabetic symptoms and their potential mechanisms. Diabetic mice were treated with DPM (150 mg/kg body weight) for 90 days and continued to be fed without DPM for an additional 30 days. Strikingly, decrease of blood glucose levels was observed in all DPM treated diabetic mice, which persisted 30 days after cessation of DPM administration. Significant decrease of glycosylated hemoglobin and hepatic pyruvate concentrations, along with marked increase of serum insulin and hepatic glycogen levels were detected in DPM treated diabetic mice. Results of a labeled 13C6-glucose uptake assay indicated that DPM can restrain glucose absorption. Additionally, DPM down-regulated the mRNA and protein expression of jejunal Na+/glucose cotransporter, Na+/K+-ATPase and glucose transporter 2, and enhanced the activities as well as mRNA and protein levels of hepatic glycolysis enzymes (glucokinase, phosphofructokinase, private kinase and pyruvate decarboxylas E1). Activity and expression of hepatic gluconeogenesis enzymes (phosphoenolpyruvate carboxykinase and glucose-6-phosphatase) were also found to be attenuated in diabetic mice treated with DPM. Purified enzyme activity assays verified that the increased activities of glucose glycolysis enzymes resulted not from their direct activation, but from the relative increase in protein expression. Importantly, our histopathological observations support the results of our biochemical analyses and validate the protective effects of DPM on STZ-induced damage to the pancreas. Thus, DPM has significant potential as a therapeutic agent against diabetes.

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“…Inhibitors include phenylalanine, thyroid hormone triiodo- l -threonine (T3), tryptophan, alanine, oxalic acid, and ribose 5-phosphate [ 9 , 10 ]. Phenylalanine and alanine have also been identified as inhibitors of M2PYK in rat and mouse [ 11 – 13 ]. In addition, tryptophan has been found to be an inhibitor of rat M2PYK [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

Redox regulation of pyruvate kinase M2 by cysteine oxidation and S-nitrosation

Mitchell

Yuan

Morgan

et al. 2018

Biochemical Journal

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We show here that the M2 isoform of human pyruvate kinase (M2PYK) is susceptible to nitrosation and oxidation, and that these modifications regulate enzyme activity by preventing the formation of the active tetrameric form. The biotin-switch assay carried out on M1 and M2 isoforms showed that M2PYK is sensitive to nitrosation and that Cys326 is highly susceptible to redox modification. Structural and enzymatic studies have been carried out on point mutants for three cysteine residues (Cys424, Cys358, and Cys326) to characterise their potential roles in redox regulation. Nine cysteines are conserved between M2PYK and M1PYK. Cys424 is the only cysteine unique to M2PYK. C424S, C424A, and C424L showed a moderate effect on enzyme activity with 80, 100, and 140% activity, respectively, compared with M2PYK. C358 had been previously identified from in vivo studies to be the favoured target for oxidation. Our characterised mutant showed that this mutation stabilises tetrameric M2PYK, suggesting that the in vivo resistance to oxidation for the Cys358Ser mutation is due to stabilisation of the tetrameric form of the enzyme. In contrast, the Cys326Ser mutant exists predominantly in monomeric form. A biotin-switch assay using this mutant also showed a significant reduction in biotinylation of M2PYK, confirming that this is a major target for nitrosation and probably oxidation. Our results show that the sensitivity of M2PYK to oxidation and nitrosation is regulated by its monomer–tetramer equilibrium. In the monomer state, residues (in particular C326) are exposed to oxidative modifications that prevent reformation of the active tetrameric form.

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The effects of the interactions between amino acids on pyruvate kinase activity from the brain cortex of young rats

Cited by 16 publications

References 21 publications

1-deoxynojirimycin inhibits glucose absorption and accelerates glucose metabolism in streptozotocin-induced diabetic mice

1-deoxynojirimycin inhibits glucose absorption and accelerates glucose metabolism in streptozotocin-induced diabetic mice

Cooperative Anti-Diabetic Effects of Deoxynojirimycin-Polysaccharide by Inhibiting Glucose Absorption and Modulating Glucose Metabolism in Streptozotocin-Induced Diabetic Mice

Redox regulation of pyruvate kinase M2 by cysteine oxidation and S-nitrosation

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