Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.1.32 (phosphoenolpyruvate carboxykinase)
 4,204 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The NH2-terminal domain of sterol-regulatory element binding protein-1a (SREBP-1a) activates transcription of genes encoding enzymes of cholesterol and fatty acid biosynthesis in cultured cells. This domain is synthesized as part of a membrane-bound precursor that is attached to the nuclear envelope and endoplasmic reticulum. In sterol-depleted cells a two-step proteolytic process releases this NH2-terminal domain, which enters the nucleus and activates transcription. Proteolysis is suppressed by sterols, thereby suppressing transcription. In the current experiments we produce transgenic mice that overexpress a truncated version of human SREBP-1a that includes the NH2-terminal domain but lacks the membrane attachment site. This protein enters the nucleus without a requirement for proteolysis, and therefore it cannot be down-regulated. Expression was driven by the phosphoenolpyruvate carboxykinase (PEPCK) promoter, which gives high level expression in liver. When placed on a low carbohydrate/high protein diet to induce the PEPCK promoter, the transgenic mice developed progressive and massive enlargement of the liver, owing to the engorgement of hepatocytes with cholesterol and triglycerides. The mRNAs encoding 3-hydroxy-3-methylglutaryl CoA (HMG CoA) synthase, HMG CoA reductase, squalene synthase, acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase-1 were all elevated markedly, as was the LDL receptor mRNA. The rates of cholesterol and fatty acid synthesis in liver were elevated 5- and 25-fold, respectively. Remarkably, plasma lipid levels were not elevated. The amount of white adipose tissue decreased progressively as the liver enlarged. These studies indicate that the NH2-terminal domain of SREBP-1a can produce major effects on lipid synthesis and storage in the liver.
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PMID:Overproduction of cholesterol and fatty acids causes massive liver enlargement in transgenic mice expressing truncated SREBP-1a. 892 2

New Zealand obese (NZO) mice exhibit severe insulin resistance of hepatic glucose metabolism. In order to define its biochemical basis, we studied the differential expression of genes involved in hepatic glucose and lipid metabolism by microarray analysis. NZOxF1 (SJLxNZO) backcross mice were generated in order to obtain populations with heterogeneous metabolism but comparable genetic background. In these backcross mice, groups of controls (normoglycemic/normoinsulinemic), insulin-resistant (normoglycemic/hyperinsulinemic) and diabetic (hyperglycemic/hypoinsulinemic) mice were identified. At 22 weeks, mRNA was isolated from liver, converted to cDNA, and used for screening of two types of cDNA arrays (high-density filter arrays and Affymetrix oligonucleotide microarrays). Differential gene expression was ascertained and assessed by Northern blotting. The data indicate that hyperinsulinemia in the NZO mouse is associated with: (i) increased mRNA levels of enzymes involved in lipid synthesis (fatty acid synthase, malic enzyme, stearoyl-CoA desaturase) or fatty acid oxidation (cytochrome P450 4A14, ketoacyl-CoA thiolase, acyl-CoA oxidase), (ii) induction of the key glycolytic enzyme pyruvate kinase, and (iii) increased mRNA levels of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase. These effects were enhanced by a high-fat diet. In conclusion, the pattern of gene expression in insulin-resistant NZO mice appears to reflect a dissociation of the effects of insulin on genes involved in glucose and lipid metabolism. The data are consistent with a hypothetical scenario in which an insulin-resistant hepatic glucose production produces hyperinsulinemia, and an enhanced insulin- and substrate-driven lipogenesis further aggravates the deleterious insulin resistance of glucose metabolism.
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PMID:Differential hepatic gene expression in a polygenic mouse model with insulin resistance and hyperglycemia: evidence for a combined transcriptional dysregulation of gluconeogenesis and fatty acid synthesis. 1476 2

1,25-Dihydroxyvitamin D3, the physiologically active form of vitamin D3, exerts its functions through a receptor-mediated mechanism and plays an important role in the cell differentiation. This study investigated the effects of 1,25-dihydroxyvitamin D3 on the proliferation and differentiation of porcine preadipocyte. Stromal-vascular cells containing preadipocytes were prepared from dorsal subcutaneous adipose tissue of approximately 3-day-old Chinese male crossbred pigs. After confluence, the differentiation was induced by transferrin, dexamethasone and insulin for 2 days, and then subsequently cultured for 6 days. The cells were treated with 1,25-dihydroxyvitamin D3 during the induction of differentiation (the early phase of differentiation) or throughout the differentiation period. The terminal differentiation markers, such as glycerol-3-phosphate dehydrogenase activity and lipid accumulation were measured during the process of cultures. The treatment with 1,25-dihydroxyvitamin D3 severely affected the induction of all differentiation markers throughout the differentiation period. 1,25-Dihydroxyvitamin D3 suppressed the expression of peroxisome proliferator-activated receptor gamma mRNA and interfered with the induction of retinoid X receptor alpha mRNA. The mRNAs of the adipogenesis-related genes, lipoprotein lipase, stearoyl-CoA desaturase, phosphoenolpyruvate carboxykinase, glycerol-3-phosphate dehydrogenase and glucose transporter 4 were reduced when 1,25-dihydroxyvitamin D3 was added into differentiation medium. Also, 1,25-dihydroxyvitamin D3 inhibited preadipocyte differentiation in dose-dependent manner. These results suggested that 1,25-dihydroxyvitamin D3 inhibited porcine preadipocyte differentiation through suppressing PPAR gamma and RXR alpha mRNA expressions and then down regulating the expression of adipogenesis-related genes.
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PMID:Effects of 1,25-dihydroxyvitamin D3 on proliferation and differentiation of porcine preadipocyte in vitro. 1780 83

n-3 highly unsaturated fatty acids (n-3 HUFAs) have been shown to suppress lipid accumulation and improve protein utilization in grass carp; however, little is known about the underlying molecular mechanism. Hence, we analyzed the hepatopancreas transcriptome of grass carp (Ctenopharyngodon idellus) fed either lard oil (LO) or fish oil (FO) diets. RNA-seq data showed that 125 genes were significantly up-regulated and 107 were significantly down-regulated in the FO group. Among them, 17 lipid metabolism related genes, 12 carbohydrate metabolism related genes, and 34 protein metabolism related genes were selected. Lipid metabolism related genes, such as very long-chain acyl-CoA synthetase (ACSVL),carnitine O-palmitoyltransferase 1 (CPT1) and carnitine-acylcarnitine translocase (CACT), were up-regulated in the FO group. But the genes of diacylglycerol O-acyltransferase 2 (DGAT2) and stearoyl-CoA desaturase (SCD) were down-regulated. Down-regulation of glycolysis related genes, such as 6-phosphofructokinase (PFK), phosphoglycerate kinase (PGK) and pyruvate dehydrogenase kinase (PDK), added with up-regulation of gluconeogenesis related genes, such as phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase), suggests lower utilization of carbohydrate of the FO group. Besides, dietary FO also influenced the protein metabolism related genes, such as up-regulation of genes involved in digestion of dietary protein, mRNA transcription, protein translation and amino acid utilization, down-regulation of genes involved in mRNA degradation and ubiquitination of protein. Interestingly, the up-regulation of mitochondrial uncoupling protein 2 (UCP2) and down-regulation of oxidative phosphorylation related genes (cytochrome c oxidase subunit 4 isoform 2 [COX4I2], HIG1 domain family member 1A [HIGD1A] and cytochrome-b5 reductase [CYB5R]) suggest that energy metabolism may be also influenced by dietary fatty acid composition. These findings presented here provide a comprehensive understanding of the molecular mechanisms governing the effects of fish oil in grass carp.
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PMID:Comparative analysis of the hepatopancreas transcriptome of grass carp (Ctenopharyngodon idellus) fed with lard oil and fish oil diets. 2586

The constitutive androstane receptor (CAR) has been reported to decrease insulin resistance along with obesity. 6,7-dimethylesculetin (DE) is an active component of Yin Zhi Huang which is a traditional Asian medicine used to treat neonatal jaundice via CAR. In this study, we examined whether DE could affect the expression of gluconeogenic and lipogenic genes via human CAR pathway using human HepG2 cells in vitro. We also studied whether DE treatment during pregnancy could prevent maternal hypertension, glucose intolerance and hyperlipidemia, and fetal overgrowth in high-fat diet (HFD)-induced obese pregnant mice. Dimethylesculetin suppressed the mRNA expression of gluconeogenic genes, phosphoenolpyruvate carboxykinase and glucose-6-phosphatase, and lipogenic genes, sterol regulatory element-binding protein 1 and stearoyl-CoA desaturase 1, and enhanced CAR-mediated transcription. Blocking the CAR-mediated pathway abolished the effect of DE in vitro. DE treatment during pregnancy could prevent maternal hypertension, glucose intolerance and hyperlipidemia, and fetal overgrowth in HFD-induced obese pregnant mice in vivo. Our data indicate that DE might be a potential therapeutic agent for obese pregnant patients with insulin resistance through CAR to prevent the perinatal outcomes such as preeclampsia, gestational diabetes, and macrosomia. Further analysis of possible complications and side effects using animal models is required.
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PMID:Dimethylesculetin ameliorates maternal glucose intolerance and fetal overgrowth in high-fat diet-fed pregnant mice via constitutive androstane receptor. 2742 90

Our team has previously demonstrated that Ganoderma lucidum polysaccharides F31 have hypoglycemic effects on diabetic mice. This study provides insight into the system-level hypoglycemic mechanisms of F31 by the integrative analysis of transcriptomics and proteomics data. To explore the omics perspective for the mechanisms of action, the protein and gene expression in the liver from the normal control (NC), diabetic db/db control mice (DC) and F31-treated db/db mice (F31) were analyzed by iTRAQ and RNA-Seq. The differential expression proteins (DEPs) and differential expression genes (DEGs) were analyzed based on their gene ontology (GO) annotations and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and the expression of DEGs and DEPs was verified by quantitative polymerase chain reaction (qPCR) and western blotting (WB). We identified sixty-five DEGs and sixty-two DEPs in the F31-treated group as compared with the DC. Integrated analysis of the RNA-Seq data and proteomics data indicated that the two DEGs/DEPs-Gck [glucokinase (GCK)] and Cyp4a12a [cytochrome P450, family 4, subfamily a, polypeptide 12a (CYP4A12A)]-showed the same trend in mRNA and protein expression levels in the comparison of F31-VS-DC. KEGG analysis revealed that the peroxisome proliferator-activated receptors (PPARs) signaling pathway was enriched in both of the comparisons of NC-VS-DC and F31-VS-DC at the protein expression level. In the analysis of the gene and protein expression of candidate proteins targeting diabetes, we found that three genes [Gck, glucose-6-phosphatase (G6Pase), phosphoenolpyruvate carboxykinase (PEPCK)] and three proteins [GCK, glucose transporter type 2 (GLUT2), pyruvate kinase (PYK) ] in the glycolysis and gluconeogenesis pathways, proteins of the Janus-activated kinase 2 (JAK2) in the insulin pathway, and two genes [Cyp4a12a and stearoyl-CoA desaturase 2 (SCD2)] in the lipid metabolism were expressed significantly differently in the F31-treated group as compared with the DC group, which played important roles in the hypoglycemic activity of F31. Cluster analysis demonstrated that microRNAs probably participated in the regulation of the genes involved the glucose metabolism. These results provide theoretical evidence for F31 as a potential functional food ingredient for the prevention and treatment of type 2 diabetes.
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PMID:Hypoglycemic mechanisms of Ganoderma lucidum polysaccharides F31 in db/db mice via RNA-seq and iTRAQ. 3046 64