Direct effects of leptin on gluconeogenesis in rat hepatocytes are equivocal, and model systems from other species have not been extensively explored in assessing the regulation of glucose metabolism by leptin. Therefore, the goal of the present study was to compare the effects of leptin on gluconeogenesis in pig and rat hepatocyte cultures as well as to investigate an underlying mechanism of a...

The aim of this work was to investigate the effect of decreased cytosolic phosphoenolpyruvate carboxykinase (PEPCK) and plastidic NADP-dependent malic enzyme (ME) on tomato (Solanum lycopersicum) ripening. Transgenic tomato plants with strongly reduced levels of PEPCK and plastidic NADP-ME were generated by RNA interference gene silencing under the control of a ripening-specific E8 promoter. Wh...

The ability of an inositol phosphate-glycan (IPG) to mimic the effects of insulin on regulation of the expression of specific mRNAs was studied in isolated hepatocytes from normal and diabetic rats. Incubation of normal liver cells with IPG (10 microM) during 90 min produced a 5-fold decrease in phosphoenolpyruvate carboxykinase (PEPCK) mRNA levels, which had been previously increased about 10-...

Vacuolar-Type H(+)-ATPase (V-ATPase) takes the central role in pumping H(+) through cell membranes of diverse organisms, which is essential for surviving acid-base fluctuating lifestyles or environments. In mammals, although glucose is believed to be an important energy source to drive V-ATPase, and phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme for gluconeogenesis, is known to be acti...

Functional retinoic acid response elements (RAREs) have been described wherein the direct repeats are separated by 1, 2 or 5 bp (termed DR1, DR2 and DR5 respectively). We have previously shown that retinoic acid receptor/retinoid X receptor (RAR/RXR) binds a DR1 RARE within the phosphoenolpyruvate carboxykinase (PEPCK) gene promoter and is the trans-acting complex that mediates the retinoic aci...

Chronic hepatitis C virus (HCV) infection greatly increases the risk for type 2 diabetes and nonalcoholic steatohepatitis; however, the pathogenic mechanisms remain incompletely understood. Here we report gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK) transcription and associated transcription factors are dramatically up-regulated in Huh.8 cells, which stably express an HCV subg...

Higher plant phosphoenolpyruvate carboxylase (PEPC) is subject to in vivo phosphorylation of a regulatory serine located in the N-terminal domain of the protein. Studies using synthetic peptide substrates and mutated phosphorylation domain photosynthetic PEPC (C4 PEPC) suggested that the interaction of phosphoenolpyruvate carboxylase kinase (PEPCk) with its target was not restricted to this dom...

An ethanolic extract of Russian tarragon, Artemisia dracunculus L., with antihyperglycemic activity in animal models was reported to decrease phosphoenolpyruvate carboxykinase (PEPCK) mRNA expression in STZ-induced diabetic rats. A quantitative polymerase chain reaction (qPCR) assay was developed for the bioactivity-guided purification of the compounds within the extract that decrease PEPCK exp...

High-fat (HF) and high-sucrose (SU) diets increase gluconeogenesis. The present study was designed to determine the contributions of pyruvate dehydrogenase, pyruvate carboxylase, phosphoenolpyruvate carboxykinase (PEPCK), and pyruvate kinase fluxes to this accelerated gluconeogenesis (GNEO) in the absence and presence of fatty acids. Male Sprague-Dawley rats were fed an HF, SU, or starch (ST) d...

The activities of pyruvate carboxylase (PC), phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (GGPase), and glycogen synthetase (GS) were determined in the cancerous and in the apparently uninvolved (host) regions of livers from primary hepatoma patients as well as in normal adult human livers and human fetal livers. The activities of these enzymes were also assayed in a fairly ...