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Prostaglandins E2 and F2 alpha increase fructose 2,6-bisphosphate levels in isolated hepatocytes.

ABSTRACT: In hepatocytes isolated from fed rats, prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha) increased, in a time- and dose-dependent manner, fructose 2,6-bisphosphate [Fru(2,6)P2] levels and stimulated the glycolytic flux. The rise in Fru(2,6)P2 was related to an increase in glucose 6-phosphate levels which resulted from the stimulation of glycogenolysis. In cells obtained from 24 h-starved rats, no effects of either PGE2 or PGF2 alpha could be observed. In addition, when the stimulation of glycogenolysis was abolished by incubation of fed-rat hepatocytes in a Ca2(+)-depleted medium, Fru(2,6)P2 levels did not increase. Furthermore, no effects of PGs on 6-phosphofructo-2-kinase activity could be observed. These results indicate that PGE2 and PGF2 alpha show similar actions to Ca2(+)-dependent hormones on hepatic glucose metabolism.

SUBMITTER: Gomez-Foix AM

PROVIDER: S-EPMC1149955 | biostudies-other | 1991 Feb

REPOSITORIES: biostudies-other

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Prostaglandins E2 and F2 alpha affect glycogen synthase and phosphorylase in isolated hepatocytes.

Project description:Prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha) inactivated glycogen synthase and activated glycogen phosphorylase in rat hepatocytes in a dose- and time-dependent manner. These effects were dependent on the presence of Ca2+ in the incubation medium. When glycogen synthase was immunoprecipitated from cells incubated with [32P]Pi and then treated with PGE2 or PGF2 alpha, there was increased phosphorylation of the 88 kDa subunit of the enzyme. This phosphorylation affected two CNBr fragments of the glycogen synthase, CB-1 and CB-2, the same fragments that are phosphorylated by different glycogenolytic hormones. No phosphorylation of glycogen synthase by prostaglandins was observed in the absence of Ca2+. Thus the effect of PGE2 and PGF2 alpha on these glycogen-metabolizing enzymes supports a role for regulation by prostaglandins of glucose metabolism in parenchymal liver cells.

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Hormonal control of fructose 2,6-bisphosphate concentration in isolated rat hepatocytes.

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The ability of adenosine to decrease the concentration of fructose 2,6-bisphosphate in isolated hepatocytes. A cyclic AMP-mediated effect.

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Fructose-2,6-bisphosphate synthesis by 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 4 (PFKFB4) is required for the glycolytic response to hypoxia and tumor growth.

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| S-EPMC4196155 | biostudies-literature

Effects of glucose and glucagon on the fructose 2,6-bisphosphate content of pancreatic islets and purified pancreatic B-cells. A comparison with isolated hepatocytes.

Project description:Glucose caused a sustained and dose-related increase in the fructose 2,6-bisphosphate content of isolated pancreatic islets, as well as of purified pancreatic B-cells. With isolated B-cells, the glucose saturation curve was sigmoidal and superimposable on that obtained with hepatocytes isolated from unfed rats. However, the response to glucose was notably faster in purified B-cells than in isolated hepatocytes. In contrast again with the situation prevailing in the liver, glucagon failed to decrease significantly the concentration of fructose 2,6-bisphosphate in either islets or purified B-cells. It is proposed that, in the process of glucose-stimulated insulin secretion, an early increase in fructose 2,6-bisphosphate formation may, by causing activation of 6-phosphofructo-1-kinase, allow glycolysis to keep pace with the rate of glucose phosphorylation.

| S-EPMC1144105 | biostudies-other

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