• Microbiology and Biotechnology Letters
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• v.34 no.1
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• pp.35-39
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• 2006

One of the fermentative metabolism of enteric Escherichia coli was imitated after rumen bacteria, which have high C4 metabolism. E. coli expresses phosphenolpyruvate carboxylase (PPC) for the pathway between phosphoenolpyruvate (PEP) and oxaloacetate (OAA) during glycolytic condition while expresses phosphoenolpyruvate carboxykinase (PCK) during gluconeogenic condition. In contrast to enteric E. coli, rumen bacteria express the PEP-OAA pathway only by PCK. To verify the effect of the regulation imitation on the C4 metabolism of E. coli, PPC-deficient E. coli strain with PCK expression in glycolytic condition was constructed. The PEP-OAA regulation modified E. coli strain increased 2.5-folds higher C4 metabolite than the wild type strain. The potential use of C4 metabolism by regulation control is discussed.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.2
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• pp.95-99
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• 2002

A pckA gene encoding phosphoenolpyruvate carboxykinase (PEPCK) was cloned and sequenced from the succinic acid producing bacterium Mannheimia succiniciproducens MBEL55E. The gene encoded a 538 residue polypeptide with a calculated molecular mass of 58.8 kDa and a calculated pI of 5.03. The deduced amino acid sequence of the M. succiniciprodutens MBEL55E PEPCK was similar to those of all known ATP-dependent PEPCKS.

• Journal of Microbiology and Biotechnology
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• v.16 no.9
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• pp.1448-1452
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• 2006

The effects of amplifying the gluconeogenic phosphoenolpyruvate carboxykinase of Escherichia coli ($pck_{Ec}$) on succinic acid production in E. coli were examined under anaerobic condition. No significant increase in succinic acid production was observed in E. coli overexpressing the $pck_{Ec}$ gene without supplementing $NaHCO_{3}$ or $MgCO_{3}$. On the other hand, succinic acid production was enhanced as the $NaHCO_{3}$ concentration was increased. When 20 g/l of $NaHCO_{3}$ was added, succinic acid production in recombinant E. coli overexpressing PCK was 2.2-fold higher than that observed in the wild-type strain. It was concluded that the gluconeogenic $pck_{Ec}$ overexpression enabled E. coli to enhance succinic acid production only under the high bicarbonate supplementation condition.

• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.361-362
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• 2006

• Molecules and Cells
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• v.45 no.4
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• pp.180-192
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• 2022

Nuclear receptor coactivator 6 (NCOA6) is a transcriptional coactivator of nuclear receptors and other transcription factors. A general Ncoa6 knockout mouse was previously shown to be embryonic lethal, but we here generated liver-specific Ncoa6 knockout (Ncoa6 LKO) mice to investigate the metabolic function of NCOA6 in the liver. These Ncoa6 LKO mice exhibited similar blood glucose and insulin levels to wild type but showed improvements in glucose tolerance, insulin sensitivity, and pyruvate tolerance. The decrease in glucose production from pyruvate in these LKO mice was consistent with the abrogation of the fasting-stimulated induction of gluconeogenic genes, phosphoenolpyruvate carboxykinase 1 (Pck1) and glucose-6-phosphatase (G6pc). The forskolin-stimulated inductions of Pck1 and G6pc were also dramatically reduced in primary hepatocytes isolated from Ncoa6 LKO mice, whereas the expression levels of other gluconeogenic gene regulators, including cAMP response element binding protein (Creb), forkhead box protein O1 and peroxisome proliferator-activated receptor γ coactivator 1α, were unaltered in the LKO mouse livers. CREB phosphorylation via fasting or forskolin stimulation was normal in the livers and primary hepatocytes of the LKO mice. Notably, it was observed that CREB interacts with NCOA6. The transcriptional activity of CREB was found to be enhanced by NCOA6 in the context of Pck1 and G6pc promoters. NCOA6-dependent augmentation was abolished in cAMP response element (CRE) mutant promoters of the Pck1 and G6pc genes. Our present results suggest that NCOA6 regulates hepatic gluconeogenesis by modulating glucagon/cAMP-dependent gluconeogenic gene transcription through an interaction with CREB.

• Food Science of Animal Resources
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• v.37 no.4
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• pp.529-534
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• 2017

Probiotics have been known to reduce high-fat diet (HFD)-induced metabolic diseases, such as obesity, insulin resistance, and type 2 diabetes. We recently observed that Lactobacillus acidophilus NS1 (LNS1), distinctly suppresses increase of blood glucose levels and insulin resistance in HFD-fed mice. In the present study, we demonstrated that oral administration of LNS1 with HFD feeding to mice significantly reduces hepatic expression of phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme in gluconeogenesis which is highly increased by HFD feeding. This suppressive effect of LNS1 on hepatic expression of PEPCK was further confirmed in HepG2 cells by treatment of LNS1 conditioned media (LNS1-CM). LNS1-CM strongly and specifically inhibited $HNF4{\alpha}-induced$ PEPCK promoter activity in HepG2 cells without change of $HNF4{\alpha}$ mRNA levels. Together, these data demonstrate that LNS1 suppresses PEPCK expression in the liver by regulating $HNF4{\alpha}$ transcriptional activity, implicating its role as a preventive or therapeutic approach for metabolic diseases.

• BMB Reports
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• v.42 no.10
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• pp.679-684
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• 2009

Fenofibrate has been proven to reduce adiposity. Since gestation produces an increase in white adipose tissue (WAT) mass, we comparatively studied this drug-effect in virgin and pregnant rats. Fenofibrate reduced lumbar WAT weight in both pregnant and virgin rats. Fenofibrate treatment did not modify plasma free fatty acid (FFA) concentration in virgin rats, it greatly increased it in pregnant animals. Remarkable differences between the two groups were obtained for two proteins related to fatty acid oxidation and esterification and storing. Respectively, the mRNA levels of carnitine palmitoyltransferase I (CPT-I) were increased by the fenofibrate only in the virgin rats and a similar finding was observed for the expression of phosphoenolpyruvate carboxykinase (PEPCK). These findings indicate that fenofibrate reduces adiposity in pregnant and virgin rats through different mechanisms: a) in virgin rats, by promoting fatty acid oxidation; and b) in pregnant rats, by enhancing fatty acid output.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.5
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• pp.552-561
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• 2017

This study aimed to investigate glucose uptake mechanisms and metabolic mechanisms for absorbed glucose in HepG2 cells treated with Acanthopanax senticosus water extract (ASW). A colorimetric assay kit was used to measure polyphenol content, glucokinase (GK) activity, glucose uptake, glucose consumption in cell culture medium, and glycogen content. RT-PCR and western blotting were performed to examine changes in the expression levels of glucose transporter 2 (GLUT2), hepatocyte nuclear factor $1{\alpha}$ ($HNF-1{\alpha}$), phosphatidylinositol 3-kinase (PI3k), protein kinase B (Akt), phospho-AMP-activated protein kinase (AMPK), phosphoenolpyruvate carboxykinase, GK, and glycogen synthase kinase $3{\beta}$ ($GSK3{\beta}$). Increased glucose uptake upon ASW treatment was confirmed to result from increased expression of $HNF-1{\alpha}$, which is one of the transcription factors acting on the GLUT2 promoter. From the measurements of GK activity, we observed that ASW had an effect on glucose phosphorylation, and we also confirmed that increased AMPK phosphorylation promoted glycolysis and suppressed gluconeogenesis. We confirmed that the increase in glycogen upon ASW treatment was induced by activation of Akt by PI3k, followed by phosphorylation of $GSK3{\beta}$. This study demonstrates that ASW activates glucose metabolic mechanisms in liver cells and is therefore a potential candidate to alleviate diabetes.

• Journal of Microbiology and Biotechnology
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• v.18 no.4
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• pp.704-710
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• 2008

Glutamate availability in the argF-argR-proB${\Delta}$ strain of Corynebacterium glutamicum was increased by addition of glutamate to the cell or inactivation of the phosphoenolpyruvate carboxykinase activity and simultaneous overexpression of the pyruvate carboxylase activity to assess its effect on L-ornithine production. When glutamate was increased in an L-ornithine-producing strain, the production of L-ornithine was not changed. This unexpected result indicated that the intracellular concentration and supply of glutamate is not a rate-limiting step for the L-ornithine production in an L-ornithine-producing strain of C. glutamicum. In contrast, overexpression of the L-ornithine biosynthesis genes (argCJBD) resulted in approximately 30% increase of L-ornithine production, from 12.73 to 16.49 mg/g (dry cell weight). These results implied that downstream reactions converting glutamate to L-ornithine, but not the availability of glutamate, is the rate-limiting step for elevating L-ornithine production in the argF-argR-proB${\Delta}$ strain of C. glutamicum.

• Nutrition Research and Practice
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• v.10 no.5
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• pp.507-515
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• 2016

BACKGROUND/OBJECTIVES: This study was designed to investigate whether Gynura procumbens extract (GPE) can improve insulin sensitivity and suppress hepatic glucose production in an animal model of type 2 diabetes. MATERIALS/METHODS: C57BL/Ksj-db/db mice were divided into 3 groups, a regular diet (control), GPE, and rosiglitazone groups (0.005 g/100 g diet) and fed for 6 weeks. RESULTS: Mice supplemented with GPE showed significantly lower blood levels of glucose and glycosylated hemoglobin than diabetic control mice. Glucose and insulin tolerance test also showed the positive effect of GPE on increasing insulin sensitivity. The homeostatic index of insulin resistance was significantly lower in mice supplemented with GPE than in the diabetic control mice. In the skeletal muscle, the expression of phosphorylated AMP-activated protein kinase, pAkt substrate of 160 kDa, and PM-glucose transporter type 4 increased in mice supplemented with GPE when compared to that of the diabetic control mice. GPE also decreased the expression of glucose-6-phosphatase and phosphoenolpyruvate carboxykinase in the liver. CONCLUSIONS: These findings demonstrate that GPE might improve insulin sensitivity and inhibit gluconeogenesis in the liver.