• Journal of Microbiology and Biotechnology
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• 제16권9호
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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.

• BMB Reports
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• 제46권12호
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• pp.567-574
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• 2013

Liver plays a major role in maintaining glucose homeostasis in mammals. Under fasting conditions, hepatic glucose production is critical as a source of fuel to maintain the basic functions in other tissues, including skeletal muscle, red blood cells, and the brain. Fasting hormones glucagon and cortisol play major roles during the process, in part by activating the transcription of key enzyme genes in the gluconeogenesis such as phosphoenol pyruvate carboxykinase (PEPCK) and glucose 6 phosphatase catalytic subunit (G6Pase). Conversely, gluconeogenic transcription is repressed by pancreatic insulin under feeding conditions, which effectively inhibits transcriptional activator complexes by either promoting post-translational modifications or activating transcriptional inhibitors in the liver, resulting in the reduction of hepatic glucose output. The transcriptional regulatory machineries have been highlighted as targets for type 2 diabetes drugs to control glycemia, so understanding of the complex regulatory mechanisms for transcription circuits for hepatic gluconeogenesis is critical in the potential development of therapeutic tools for the treatment of this disease. In this review, the current understanding regarding the roles of two key transcriptional activators, CREB and FoxO1, in the regulation of hepatic gluconeogenic program is discussed.

• Food Science and Biotechnology
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• 제17권6호
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• pp.1146-1150
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• 2008

Peroxisome proliferator-activated receptor-gamma ($PPAR_{\gamma}$), a member of the nuclear receptor of ligand-activated transcription factors, plays a key role in lipid and glucose metabolism or adipocytes differentiation. A lignan compound was isolated from mace (the aril of Myristica fragrans Houtt.) as a $PPAR_{\gamma}$ ligand, which was identified as fragrin A or 2-(4-allyl-2,6-dimethoxyphenoxy)-1-(4-hydroxy-3-methoxyphenyl)-propane. To ascertain whether fragrin A has $PPAR_{\gamma}$ ligand-binding activity, it was performed that GAL-4/$PPAR_{\gamma}$ transactivation assay. $PPAR_{\gamma}$ ligand-binding activity of fragrin A increased 4.7, 6.6, and 7.3-fold at 3, 5, and $10{\mu}M$, respectively, when compared with a vehicle control. Fragrin A also enhanced adipocytes differentiation and increased the expression of $PPAR_{\gamma}$ target genes such as adipocytes fatty acid-binding protein (aP2), lipoprotein lipase (LPL), and phosphoenol pyruvate carboxykinase (PEPCK). Furthermore, it significantly increased the expression level of glucose transporter 4 (GLUT4). These results indicate that fragrin A can be developed as a $PPAR_{\gamma}$ agonist for the improvement of insulin resistance associated with type 2 diabetes.

• Biomolecules & Therapeutics
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• 제31권6호
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• pp.619-628
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• 2023

In the modern era, chronic kidney failure due to diabetes has spread across the globe. Prunetin (PRU), a component of herbal medicines, has a broad variety of pharmacological activities; these may help to slow the onset of diabetic kidney disease. The anti-nephropathic effects of PRU have not yet been reported. The present study explored the potential nephroprotective actions of PRU in diabetic rats. For 28 days, nephropathic rats were given oral doses of PRU (20, 40, and 80 mg/kg). Body weight, blood urea, creatinine, total protein, lipid profile, liver marker enzymes, carbohydrate metabolic enzymes, C-reactive protein, antioxidants, lipid peroxidative indicators, and the expression of insulin receptor substrate 1 (IRS-1) and glucose transporter 2 (GLUT-2) mRNA genes were all examined. Histological examinations of the kidneys, liver, and pancreas were also performed. The oral treatment of PRU drastically lowered the blood glucose, HbA1c, blood urea, creatinine, serum glutamic-oxaloacetic transaminase, serum glutamic pyruvic transaminase, alkaline phosphatase, lipid profile, and hexokinase. Meanwhile, the levels of fructose 1,6-bisphosphatase, glucose-6-phosphatase, and phosphoenol pyruvate carboxykinase were all elevated, but glucose-6-phosphate dehydrogenase dropped significantly. Inflammatory marker antioxidants and lipid peroxidative markers were also less persistent due to this administration. PRU upregulated the IRS-1 and GLUT-2 gene expression in the nephropathic group. The possible renoprotective properties of PRU were validated by histopathology of the liver, kidney, and pancreatic tissues. It is therefore proposed that PRU (80 mg/kg) has considerable renoprotective benefits in diabetic nephropathy in rats.

• Asian-Australasian Journal of Animal Sciences
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• 제26권2호
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• pp.202-210
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• 2013

This study elucidated the effects of limited concentrate feeding on growth, plasma profile, and gene expression of gluconeogenic enzymes and visfatin in the liver of Hanwoo beef calves. The purpose of this study was to test that reducing the amount of concentrate would partially be compensated by increasing the intake of forage and by altering the metabolic status. The study utilized 20 Korean native beef calves (Hanwoo; 60 to 70 d of age) divided into two groups of 10 calves each for 158 d. Control group calves received the amount of concentrate as per the established Korean feeding standards for Hanwoo, whereas calves in the restricted group only received half the amount of concentrate as per standard requirements. Good quality forage (Timothy hay) was available for ad libitum consumption to both groups. Since calves were with their dam until 4 months of age in breeding pens before weaning, the intake of milk before weaning was not recorded, however, the concentrate and forage intakes were recorded daily. Body weights (BW) were recorded at start and on 10 d interval. Blood samples were collected at start and at 50 d interval. On the final day of the experiment, liver biopsies were collected from all animals in each group. The BW was not different between the groups at all times, but tended to be higher (p = 0.061) only at final BW in control than restricted group. Total BW gain in the control group was 116.2 kg as opposed to 84.1 kg in restricted group that led to average BW gain of 736 g/d and 532 g/d in respective groups, and the differences were significant (p<0.01). As planned, the calves in the control group had higher concentrate and lower forage intake than the restricted group. The plasma variables like total protein and urea were higher (p<0.05) in control than restricted group. The mRNA expressions for the gluconeogenic enzymes such as cytosolic phosphoenol pyruvate carboxykinase (EC 4.1.1.32) and pyruvate carboxylase (EC 6.4.1.1), and visfatin measured by quantitative real-time PCR in liver biopsies showed higher expression (p<0.05) in restricted group than control. Overall, restricting concentrate severely reduced the growth intensity and affected few plasma indices, and gene expression in liver was increased indicating that restricting concentrate in the feeding schemes during early growth for beef calves is not advocated.

• Journal of Dairy Science and Biotechnology
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• 제39권2호
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• pp.78-85
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• 2021

본 연구는 고지방식이 마우스에서 체중 감소, 혈당 감소 및 인슐린 저항성 개선 효과를 가지는 LNS1 균주의 간 내 글리코겐 함량에 미치는 영향을 조사하여 고지방식이에 의한 비정상적인 글리코겐 대사 개선을 위한 활용 가능성을 검토하고자 실시하였다. LNS1을 12주간 경구 투여한 고지방식이 마우스의 간에서 포도당 운반체 단백질인 GLUT2와 글리코겐 합성의 주요 효소인 GCK, GYS2의 유전자 발현 변화를 확인한 결과, LNS1의 경구 투여는 고지방식이 마우스에 비해 GLUT2와 GYS2의 유전자 발현을 각각 약 2배, 1.8배 증가시켰으며, GCK의 발현에는 영향을 주지 않는 것으로 확인되었다. 또한, GCK의 regulatory unit으로 작용하여 GCK의 활성을 억제하는 GCKR와 글리코겐 분해 과정의 주요 효소인 G6PC의 발현은 LNS1 투여에 의해 HFD마우스에 비해 각각 약 53%, 32% 감소함을 보였다. 간 조직에서의 결과와 마찬가지로 HepG2 세포에 LNS1-CM의 처리는 GLUT2와 GYS2의 유전자 발현을 약 1.9배, 2배 증가시켰으며, GCK의 발현 변화에는 영향을 주지 않는 것으로 확인되었다. GCKR과 G6PC의 유전자 발현 또한 LNS1-CM 처리에 의해 각각 77%, 47% 감소함을 보였다. 또한, 간 조직 내 글리코겐 함량은 고지방식이와 LNS1 투여를 병행한 마우스에서 고지방식이 마우스에 비해 약 1.5배 증가한 것으로 조사되었다. 위의 결과들을 종합해 볼 때, LNS1은 GLUT2, GYS2, GCKR와 G6PC의 발현 조절을 통해 간 조직내 글리코겐 함량을 증가시켜 고지방식이에 의한 글리코겐 대사 이상을 개선시키는 효과를 가지는 것으로 사료된다.