scholarly journals Role of upstream stimulatory factor 2 in glutamate dehydrogenase gene transcription

2018 ◽  
Vol 60 (3) ◽  
pp. 247-259 ◽  
Author(s):  
Carlos Gaspar ◽  
Jonás I Silva-Marrero ◽  
María C Salgado ◽  
Isabel V Baanante ◽  
Isidoro Metón
Keyword(s):  
Transcriptional Regulation ◽  
Tissue Distribution ◽  
Glutamate Dehydrogenase ◽  
Sea Bream ◽  
Mrna Levels ◽  
Nutritional Regulation ◽  
Upstream Stimulatory Factor ◽  
Hepatic Expression ◽  
Stimulatory Factor

Glutamate dehydrogenase (Gdh) plays a central role in ammonia detoxification by catalysing reversible oxidative deamination of l-glutamate into α-ketoglutarate using NAD+ or NADP+ as cofactor. To gain insight into transcriptional regulation of glud, the gene that codes for Gdh, we isolated and characterised the 5′ flanking region of glud from gilthead sea bream (Sparus aurata). In addition, tissue distribution, the effect of starvation as well as short- and long-term refeeding on Gdh mRNA levels in the liver of S. aurata were also addressed. 5′-Deletion analysis of glud promoter in transiently transfected HepG2 cells, electrophoretic mobility shift assays, chromatin immunoprecipitation (ChIP) and site-directed mutagenesis allowed us to identify upstream stimulatory factor 2 (Usf2) as a novel factor involved in the transcriptional regulation of glud. Analysis of tissue distribution of Gdh and Usf2 mRNA levels by reverse transcriptase-coupled quantitative real-time PCR (RT-qPCR) showed that Gdh is mainly expressed in the liver of S. aurata, while Usf2 displayed ubiquitous distribution. RT-qPCR and ChIP assays revealed that long-term starvation down-regulated the hepatic expression of Gdh and Usf2 to similar levels and reduced Usf2 binding to glud promoter, while refeeding resulted in a slow but gradual restoration of both Gdh and Usf2 mRNA abundance. Herein, we demonstrate that Usf2 transactivates S. aurata glud by binding to an E-box located in the proximal region of glud promoter. In addition, our findings provide evidence for a new regulatory mechanism involving Usf2 as a key factor in the nutritional regulation of glud transcription in the fish liver.

scholarly journals Nutritional regulation of glucose-6-phosphatase gene expression in liver of the gilthead sea bream (Sparus aurata)

2002 ◽  
Vol 88 (6) ◽  
pp. 607-614 ◽  
Author(s):  
A. Caseras ◽  
I. Metón ◽  
C. Vives ◽  
M. Egea ◽  
F. Fernández ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Sparus Aurata ◽  
Gilthead Sea Bream ◽  
Sea Bream ◽  
Metabolic Adaptation ◽  
Mrna Levels ◽  
Nutritional Regulation ◽  
Carnivorous Fish ◽  
Hepatic Expression ◽  
Glucose Levels

To examine the role of glucose-6-phosphatase (G6Pase) in glucose homeostasis in the diabetes-like experimental model of carnivorous fish, we analysed postprandial variations and the effect of starvation, ration size and diet composition on the regulation of G6Pase expression at the enzyme activity and mRNA level in the liver of gilthead sea bream (Sparus aurata). G6Pase expression increased in long-term starved or energy-restricted fish. In contrast to data reported for other fish species, short-term regulation of G6Pase expression was found in regularly fedS. aurata. G6Pase mRNA levels were lowest between 4 and 15 h after food intake, whereas minimal enzyme activity was observed 10–15 h postprandially. Alterations of plasma glucose levels affect G6Pase in mammals. However, the carbohydrate content of the diet did not affect hepatic expression of G6Pase inS. aurata, suggesting that a different molecular mechanism is involved in the control of G6Pase expression in fish. Although G6Pase was unaffected, high-carbohydrate low-protein diets increased glucokinase (GK) expression and thus allowed a metabolic adaptation favouring glycolysis over gluconeogenesis. Interestingly, only the nutritional conditions that promoted variations in the blood glucose levels resulted in changes in the hepatic expression of G6Pase. These findings indicate a concerted regulation of G6Pase and GK expression and suggest that the direction and rate of the glucose–glucose-6-phosphate substrate cycle flux is finely regulated in the liver ofS. aurata, challenging the role attributed to deficient regulation of G6Pase or GK expression in the low ability of carnivorous fish to metabolize glucose.

scholarly journals Response of ApoA-IV in pigs to long-term increased dietary oil intake and to the degree of unsaturation of the fatty acids

2004 ◽  
Vol 92 (5) ◽  
pp. 763-769 ◽  
Author(s):  
María A. Navarro ◽  
Sergio Acín ◽  
Ricardo Carnicer ◽  
Mario A. Guzmán-García ◽  
José M. Arbonés-Mainar ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Sunflower Oil ◽  
Control Diet ◽  
Dietary Lipids ◽  
Degree Of Saturation ◽  
Plasma Lipoproteins ◽  
Mrna Levels ◽  
Hepatic Expression

ApoA-IV is a protein constituent of HDL particles; the gene coding for it is a member of the ApoA-I–ApoC-III–ApoA-IV cluster. To investigate the effects of the quantity and the degree of saturation of dietary lipid on the long-term response of this Apo, and on the hypothetical coordinated regulation of the cluster in vivo, pigs were fed isoenergetic, cholesterol-free, low-lipid or lipid-enriched diets (containing either extra olive oil (rich in MUFA) or sunflower oil (rich in n−6 PUFA)) for 42 d. In animals fed on the control diet, ApoA-IV was mainly associated with plasma lipoproteins. An increase in plasma ApoA-IV concentration, mainly in the lipoprotein-free fraction, was induced by the lipid-enriched diets, independent of the degree of saturation of the fatty acids involved. The latter diets also led to increases in hepatic ApoA-I, ApoA-IV and ApoC-III mRNA levels, more so with the sunflower oil-rich diet. The present results show that porcine plasma ApoA-IV levels and their association with lipoproteins are very sensitive to increases in dietary lipids, independent of the degree of fatty acid saturation. Furthermore, hepatic expression of RNA appears to be coordinated along with that of the other members of the gene cluster.

scholarly journals Downregulation of tenascin expression by glucocorticoids in bone marrow stromal cells and in fibroblasts.

1993 ◽  
Vol 123 (4) ◽  
pp. 1037-1045 ◽  
Author(s):  
M Ekblom ◽  
R Fässler ◽  
B Tomasini-Johansson ◽  
K Nilsson ◽  
P Ekblom
Keyword(s):  
Bone Marrow ◽  
Tissue Distribution ◽  
Stromal Cells ◽  
Regulatory Elements ◽  
Mrna Levels ◽  
Glucocorticoid Treatment ◽  
Bone Marrow Cultures ◽  
Stromal Cell Line ◽  
Marrow Cultures

Tenascin, a predominantly mesenchymal extracellular matrix (ECM) glycoprotein has a rather restricted tissue distribution, but until now factors that inhibit its expression have not been identified. Glucocorticoids are known to be beneficial for establishment of myelopoiesis in long-term bone marrow cultures. Tenascin was found to be expressed in the bone marrow, and glucocorticoids were found to affect bone marrow tenascin expression. Both tenascin mRNAs and the mRNA of another ECM protein, laminin B1 chain, were drastically downregulated by glucocorticoids during initiation of bone marrow cultures. However, in already established long-term cultures glucocorticoids did not affect laminin B1 chain mRNA levels although tenascin mRNAs continued to be downregulated. Studies with a stromal cell line (MC3T3-G2/PA6) and fibroblasts (3T3) suggested that glucocorticoids act directly on the stromal cells that produce tenascin. In 3T3 cells this downregulation occurred within 12 h of glucocorticoid-treatment, suggesting that glucocorticoids acted through cis regulatory elements of the tenascin gene. We suggest that glucocorticoids in part regulate hematopoiesis by modifying the ECM. Furthermore, downregulation of tenascin expression by glucocorticoids may in part explain the restricted tissue distribution of tenascin in other tissues.

scholarly journals Transactivation of cytosolic alanine aminotransferase gene promoter by p300 and c-Myb

2010 ◽  
Vol 45 (3) ◽  
pp. 119-132 ◽  
Author(s):  
Ida G Anemaet ◽  
Juan Diego González ◽  
María C Salgado ◽  
Marina Giralt ◽  
Felipe Fernández ◽  
...  
Keyword(s):  
Transcriptional Regulation ◽  
Transcriptional Activation ◽  
Alanine Aminotransferase ◽  
Sparus Aurata ◽  
Gene Promoter ◽  
Sea Bass ◽  
Sea Bream ◽  
Mrna Levels ◽  
Mobility Shift ◽  
Sea Bass Larvae

Alanine aminotransferase (Alt) provides a molecular link between carbohydrate and amino acid metabolism. In the cell context, the predominant Alt isozyme is located in the cytosol. To gain insight into the transcriptional regulation of the cytosolic alt gene (calt), we cloned and characterized the calt promoter from gilthead sea bream (Sparus aurata). Transient transfection of sea bass larvae cells with deleted calt promoter constructs and electrophoretic mobility shift assays allowed us to identify p300 and c-Myb as new factors in the transcriptional regulation of calt expression. Transfection studies carried out with an acetylase-deficient mutant p300 (p300DY) revealed that the acetyltransferase activity of p300 is essential for the p300-mediated transcriptional activation of S. aurata calt. We had previously found up-regulation of liver cAlt2, an alternatively spliced isoform of calt, under gluconeogenic conditions and in streptozotocin (STZ)-treated S. aurata. Quantitative RT-PCR assays showed that increased p300 and c-Myb mRNA levels in the liver of starved S. aurata contribute to enhancing the transcription of cAlt2. Consistently, the administration of insulin decreased both p300 and c-Myb expression. The mRNA levels of p300 and c-Myb were also analyzed in the liver of STZ-induced diabetic S. aurata. Treatment with STZ increased the expression of p300, whereas it decreased c-Myb. Our findings suggest an involvement of p300 and c-Myb in up-regulation of cAlt2 in the liver of S. aurata under starvation. In addition, these results provide evidence for a role of p300 in diabetes.

The effect of long term under- and over-feeding on the expression of six major milk protein genes in the mammary tissue of sheep

2015 ◽  
Vol 82 (3) ◽  
pp. 257-264 ◽  
Author(s):  
Eleni Tsiplakou ◽  
Emmanouil Flemetakis ◽  
Evangelia-Diamanto Kouri ◽  
George Karalias ◽  
Kyriaki Sotirakoglou ◽  
...  
Keyword(s):  
Gene Expression ◽  
Milk Protein ◽  
Milk Proteins ◽  
Protein Yield ◽  
Mammary Tissue ◽  
Mrna Levels ◽  
Nutritional Regulation ◽  
Milk Protein Genes ◽  
Milk Volume

Milk protein synthesis in the mammary gland involves expression of six major milk protein genes whose nutritional regulation remains poorly defined. In this study, the effect of long term under- and over-feeding on the expression of αs1-casein: CSN1S1, αs2-casein: CSN1S2, β-casein: CSN2, κ-casein: CSN3, α-lactalbumin: LALBA and β-lactoglobulin: BLG gene in sheep mammary tissue (MT) was examined. Twenty-four lactating dairy sheep, at 90–98 d in milk, were divided into three groups and fed the same ration, for 60 d, in quantities which met 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed a significant reduction on mRNA of CSN1S1, CSN1S2, CSN2 and BLG gene in the MT of underfed sheep compared with the overfed ones and a significant reduction in CSN3 and LALBA gene expression compared with the respective control animals. Significant positive correlations were observed between the mRNA levels of milk proteins’ genes with the milk protein yield and milk yield respectively. In conclusion, the feeding level and consequently the nutrients availability, affected the milk protein yield and milk volume by altering the CSN1S1, CSN1S2, CSN2, CSN3, LALBA and BLG gene expression involved in their metabolic pathways.

scholarly journals Sterol Regulatory Element Binding Protein-1a Transactivates 6-Phosphofructo-2-Kinase/Fructose-2,6-Bisphosphatase Gene Promoter

Endocrinology ◽  
2006 ◽  
Vol 147 (7) ◽  
pp. 3446-3456 ◽  
Author(s):  
Isidoro Metón ◽  
Miriam Egea ◽  
Ida G. Anemaet ◽  
Felipe Fernández ◽  
Isabel V. Baanante
Keyword(s):  
Transcriptional Activation ◽  
Sparus Aurata ◽  
Binding Protein ◽  
Regulatory Element ◽  
Gene Promoter ◽  
Sea Bream ◽  
Proximal Promoter ◽  
Mrna Levels ◽  
Nutritional Regulation ◽  
Sterol Regulatory Element

6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB) catalyzes the synthesis and degradation of fructose-2,6-bisphosphate, a key modulator of glycolysis-gluconeogenesis. To gain insight into the molecular mechanism behind hormonal and nutritional regulation of PFKFB expression, we have cloned and characterized the proximal promoter region of the liver isoform of PFKFB (PFKFB1) from gilthead sea bream (Sparus aurata). Transient transfection of HepG2 cells with deleted gene promoter constructs and electrophoretic mobility shift assays allowed us to identify a sterol regulatory element (SRE) to which SRE binding protein-1a (SREBP-1a) binds and transactivates PFKFB1 gene transcription. Mutating the SRE box abolished SREBP-1a binding and transactivation. The in vivo binding of SREBP-1a to the SRE box in the S. aurata PFKFB1 promoter was confirmed by chromatin immunoprecipitation assays. There is a great deal of evidence for a postprandial rise of PFKB1 mRNA levels in fish and rats. Consistently, starved-to-fed transition and treatment with glucose or insulin increased SREBP-1 immunodetectable levels, SREBP-1 association to PFKFB1 promoter, and PFKFB1 mRNA levels in the piscine liver. Our findings demonstrate involvement of SREBP-1a in the transcriptional activation of PFKFB1, and we conclude that SREBP-1a may exert a key role mediating postprandial activation of PFKFB1 transcription.

Programming into adulthood of islet adaptations induced by early nutritional intervention in the rat

2001 ◽  
Vol 281 (3) ◽  
pp. E640-E648 ◽  
Author(s):  
Ravikumar Aalinkeel ◽  
Malathi Srinivasan ◽  
Fei Song ◽  
Mulchand S. Patel
Keyword(s):  
Adult Life ◽  
Nutritional Intervention ◽  
Milk Formula ◽  
Mrna Levels ◽  
Suckling Period ◽  
Upstream Stimulatory Factor ◽  
Adult Rats ◽  
Phosphatidylinositol Kinase ◽  
Upstream Stimulatory Factor 1 ◽  
Stimulatory Factor

To investigate the influence of a high carbohydrate (HC) intake during the suckling period on pancreatic function in adult life, neonatal rats were artificially reared on a HC milk formula during the preweaning period and then weaned onto lab chow. In the adult HC rat, hyperinsulinemia is sustained by a variety of biochemical and molecular adaptations induced in the HC islets during the suckling period. The adult HC islets showed a distinct left shift in the glucose-stimulated insulin-secretory pattern. HC islets were also able to secrete moderate levels of insulin in the absence of glucose and in the presence of Ca2+channel inhibitors. In addition, the mRNA levels of preproinsulin, somatostatin transcription factor-1, upstream stimulatory factor-1, stress-activated protein kinase-2, phosphatidylinositol kinase, and GLUT-2 genes were significantly increased in HC islets. These results show that consumption of a HC formula during the suckling period programs pancreatic islet function in adult rats, resulting in the maintenance of hyperinsulinemia in the postweaning period and eventually leading to the development of obesity in adult life.

scholarly journals Severe Hepatic Insulin Resistance Induces Vascular Dysfunction: Improvement by Liver-Specific Insulin Receptor Isoform A Gene Therapy in a Murine Diabetic Model

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 2035
Author(s):  
Almudena Gómez-Hernández ◽  
Natalia de las Heras ◽  
Andrea R. López-Pastor ◽  
Gema García-Gómez ◽  
Jorge Infante-Menéndez ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Gene Therapy ◽  
Insulin Receptor ◽  
Vascular Dysfunction ◽  
Hepatic Insulin Resistance ◽  
Specific Gene ◽  
Mrna Levels ◽  
Hepatic Expression ◽  
Specific Insulin

Background: Cardiovascular dysfunction is linked to insulin-resistant states. In this paper, we analyzed whether the severe hepatic insulin resistance of an inducible liver-specific insulin receptor knockout (iLIRKO) might generate vascular insulin resistance and dysfunction, and whether insulin receptor (IR) isoforms gene therapy might revert it. Methods: We studied in vivo insulin signaling in aorta artery and heart from iLIRKO. Vascular reactivity and the mRNA levels of genes involved in vascular dysfunction were analyzed in thoracic aorta rings by qRT-PCR. Finally, iLIRKO mice were treated with hepatic-specific gene therapy to analyze vascular dysfunction improvement. Results: Our results suggest that severe hepatic insulin resistance was expanded to cardiovascular tissues. This vascular insulin resistance observed in aorta artery from iLIRKO mice correlated with a reduction in both PI3K/AKT/eNOS and p42/44 MAPK pathways, and it might be implicated in their vascular alterations characterized by endothelial dysfunction, hypercontractility and eNOS/iNOS levels’ imbalance. Finally, regarding long-term hepatic expression of IR isoforms, IRA was more efficient than IRB in the improvement of vascular dysfunction observed in iLIRKO mice. Conclusion: Severe hepatic insulin resistance is sufficient to produce cardiovascular insulin resistance and dysfunction. Long-term hepatic expression of IRA restored the vascular damage observed in iLIRKO mice.

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