| 11. |
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| 12. |
- Ahlzén, Maja, et al.
(författare)
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Expression of the transcription factor 7-like 2 gene (TCF7L2) in human adipocytes is down regulated by insulin.
- 2008
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Ingår i: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 370, s. 49-52
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Tidskriftsartikel (refereegranskat)abstract
- Variants in the TCF7L2 gene (transcription factor 7-like 2) have shown strong association with type 2 diabetes with two defined risk haplotypes, HapA and HapB(T2D). TCF7L2 may play a role in both glucose homeostasis and adipogenesis. Our aim was to characterize the TCF7L2 mRNA expression and regulation in human adipose tissue. We quantified TCF7L2 mRNA levels in cultured human adipocytes and in biopsies from visceral (VAT) and subcutaneous (SAT) adipose tissue from 38 obese non-diabetic subjects, using real-time PCR. The influence of haplotype and clinical traits on TCF7L2 mRNA levels were investigated. In vitro, insulin decreased TCF7L2 mRNA expression. This effect was attenuated in cells incubated with the free fatty acids palmitate or oleate. In vivo, we found significantly higher expression in SAT from more insulin resistant subjects. No correlations between TCF7L2 mRNA expression and obesity measures were observed. TCF7L2 expression was higher in VAT than in SAT and when stratifying for haplotype, this difference was seen in HapA carriers but not in non-HapA carriers. In conclusion, TCF7L2 mRNA levels in adipocytes are decreased by insulin and seem to increase in insulin resistant subjects and in HapA carriers.
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| 13. |
- Fredriksson, Jenny, et al.
(författare)
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A polymorphism in the adiponectin gene influences adiponectin expression levels in visceral fat in obese subjects
- 2006
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Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 1476-5497 .- 0307-0565. ; 30:2, s. 226-232
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Reduced serum adiponectin levels have been found in obesity and type 2 diabetes and variations in the adiponectin gene (APM1) have been associated with type 2 diabetes and features of the metabolic syndrome in different populations. Study Design: Here, we investigated the expression of APM1 in adipose tissue and studied the relationship between variation in APM1 expression, the APM1 G276T polymorphism, the common PPARG Pro12Ala polymorphism and clinical features of 36 morbidly obese (body mass index (BMI) 41.5 +/- 4.9 kg/m(2)) nondiabetic subjects. Results: APM1 mRNA expression in visceral fat was correlated with serum adiponectin levels (r=0.54, P=0.012). In visceral, but not in subcutaneous, adipose tissue APM1 mRNA level was 38% higher among carriers of the APM1 G276T T allele (G/T and T/T) than among carriers of the G/G genotype (0.91 +/- 0.06 for G/T and T/T carriers vs 0.66 +/- 0.09 for G/G carriers, P=0.013). Carriers of the T allele also had significantly higher body fat percent compared to G/G carriers (65 +/- 6 vs 56 +/- 10%, P=0.011). Conclusion: Our results indicate that genetic variation in APM1 influences the expression of the gene in visceral adipose tissue and suggest a potential role for such variation in regulation of body fat accumulation in obese subjects.
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| 14. |
- Fredriksson, Jenny, et al.
(författare)
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Characterization of the human skeletal muscle glycogen synthase gene (GYS1) promoter.
- 2004
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Ingår i: European Journal of Clinical Investigation. - : Wiley. - 0014-2972 .- 1365-2362. ; 34:2, s. 113-121
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Tidskriftsartikel (refereegranskat)abstract
- Background Impaired activation of the human skeletal muscle glycogen synthase by insulin is typical for type 2 diabetic patients. Regulation of glycogen synthase occurs mainly by phosphorylation/dephoshorylation but little is known whether there also is transcriptional regulation. Therefore we studied transcriptional regulation of the human skeletal muscle glycogen synthase gene (GYS1) and evaluated the effects of insulin and forskolin on the promoter activity. Methods Seven promoter fragments were expressed in C2C12 myoblasts and myotubes and in HEK293 cells, and the luciferase assay was used to determine transcriptional activity. Results The highest luciferase activity, 350-fold of the promoterless vector, was obtained with nucleotides -692 to +59 in myotubes (P < 0·001), while the nucleotides -250 to +59 provided the highest, 45-fold, activity in the HEK293 cells (P < 0·001). Longer promoter constructs (nucleotides -971, -1707 and -2158 to +59, respectively) had low promoter activity in both cell types. Forskolin treatment for 24 h resulted in approximately 30% decreased promoter activity in myotubes (P < 0·05). Insulin treatment for 0·5-3 h did not increase GYS1 promoter activity; instead the activity was slightly but significantly decreased after 24 h in myotubes (P < 0·005). Conclusions From our results we conclude that basal GYS1 promoter activity is obtained from the first 250 nucleotides of the promoter, while the nucleotides -692 to -544 seem to be responsible for muscle-specific expression, and nucleotides -971 to -692 for negative regulation. In myotubes, the GYS1 promoter was sensitive to negative regulation by forskolin, whereas insulin did not increase GYS1 transcription.
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| 15. |
- Kotronen, Anna, et al.
(författare)
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Prediction of Non-Alcoholic Fatty Liver Disease and Liver Fat Using Metabolic and Genetic Factors
- 2009
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Ingår i: Gastroenterology. - : Elsevier BV. - 1528-0012 .- 0016-5085. ; 137:3, s. 865-872
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND & AIMS: Our aims were to develop a method to accurately predict non-alcoholic fatty liver disease (NAFLD) and liver fat content based on routinely available clinical and laboratory data and to test whether knowledge of the recently discovered genetic variant in the PNPLA3 gene (rs738409) increases accuracy of the prediction. METHODS: Liver fat content was measured using proton magnetic resonance spectroscopy in 470 subjects, who were randomly divided into estimation (two thirds of the subjects, n = 313) and validation (one third of the subjects, n = 157) groups. Multivariate logistic and linear regression analyses were used to create an NAFLD liver fat score to diagnose NAFLD and liver fat equation to estimate liver fat percentage in each individual. RESULTS: The presence of the metabolic syndrome and type 2 diabetes, fasting serum (fS) insulin, FS-aspartate aminotransferase (AST), and the AST/alanine aminotransferase ratio were independent predictors of NAFLD. The score had an area under the receiver operating characteristic curve of 0.87 in the estimation and 0.86 in the validation group. The optimal cut-off point of -0.640 predicted increased liver fat content with sensitivity of 86% and specificity of 71%. Addition of the genetic information to the score improved the accuracy of the prediction by only <1%. Using the same variables, we developed a liver fat equation from which liver fat percentage of each individual could be estimated. CONCLUSIONS: The NAFLD liver fat score and liver fat equation provide simple and noninvasive tools to predict NAFLD and liver fat content.
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| 16. |
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| 17. |
- Lantz, Mikael, et al.
(författare)
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Thyrostimulin (a TSH-like Hormone) Expression in Orbital and Thyroid Tissue.
- 2007
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Ingår i: Thyroid. - : Mary Ann Liebert Inc. - 1557-9077 .- 1050-7256. ; 17:2, s. 113-118
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate gene expression of thyrostimulin in orbital and thyroid tissue from patients with and without Graves' disease. Design: Real-time reverse transcriptase polymerase chain reaction (RT-PCR) was used for detection of thyrostimulin gene expression in intraorbital adipose tissue from patients with severe ophthalmopathy and thyroid healthy controls in addition to thyrostimulin expression in normal thyroid tissue, multinodular goiter tissue, and Graves' thyroid tissue. Main Outcome: In intraorbital tissue, thyrostimulin expression was identified in both patients and controls with fluorescence intensities varying between 0.23 and 0.88 in patients and 0.29 and 8.9 in controls before treatment with DNase. The signal of thyrostimulin was weak or absent in intraorbital adipose tissue from patients with ophthalmopathy and thyroid healthy controls after treatment of samples with DNase. This was in contrast to the expression of the thyroid-stimulating hormone (TSH) receptor and the housekeeping gene cyclophilin A that were detected both before and after DNase treatment. Similar results were found when analyzing human and rat thyroid tissue. Conclusions: Neither did we demonstrate gene expression of thyrostimulin in intraorbital adipose tissue or in thyroid tissue, nor could we confirm earlier findings in rat thyroid tissue. Whether thyrostimulin is a regulator of thyroid function has to be further investigated in future studies.
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| 18. |
- Ling, Charlotte, et al.
(författare)
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Multiple environmental and genetic factors influence skeletal muscle PGC-1alpha and PGC-1beta gene expression in twins.
- 2004
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Ingår i: Journal of Clinical Investigation. - 0021-9738. ; 114:10, s. 1518-1526
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Tidskriftsartikel (refereegranskat)abstract
- Genetic and environmental factors contribute to age-dependent susceptibility to type 2 diabetes. Recent studies have reported reduced expression of PPAR{gamma} coactivator 1{alpha} (PGC-1{alpha}) and PGC-1ß genes in skeletal muscle from type 2 diabetic patients, but it is not known whether this is an inherited or acquired defect. To address this question we studied expression of these genes in muscle biopsies obtained from young and elderly dizygotic and monozygotic twins without known diabetes before and after insulin stimulation and related the expression to a Gly482Ser variant in the PGC-1{alpha} gene. Insulin increased and aging reduced skeletal muscle PGC-1{alpha} and PGC-1ß mRNA levels. This age-dependent decrease in muscle gene expression was partially heritable and influenced by the PGC-1{alpha} Gly482Ser polymorphism. In addition, sex, birth weight, and aerobic capacity influenced expression of PGC-1{alpha} in a complex fashion. Whereas expression of PGC-1{alpha} in muscle was positively related to insulin-stimulated glucose uptake and oxidation, PGC-1ß expression was positively related to fat oxidation and nonoxidative glucose metabolism. We conclude that skeletal muscle PGC-1{alpha} and PGC-1ß expression are stimulated by insulin and reduced by aging. The data also suggest different regulatory functions for PGC-1{alpha} and PGC-1ß on glucose and fat oxidation in muscle cells. The finding that the age-dependent decrease in the expression of these key genes regulating oxidative phosphorylation is under genetic control could provide an explanation by which an environmental trigger (age) modifies genetic susceptibility to type 2 diabetes.
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| 19. |
- Loos, Ruth J. F., et al.
(författare)
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Common variants near MC4R are associated with fat mass, weight and risk of obesity
- 2008
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 40:6, s. 768-775
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Tidskriftsartikel (refereegranskat)abstract
- To identify common variants influencing body mass index (BMI), we analyzed genome-wide association data from 16,876 individuals of European descent. After previously reported variants in FTO, the strongest association signal (rs17782313, P = 2.9 x 10(-6)) mapped 188 kb downstream of MC4R (melanocortin-4 receptor), mutations of which are the leading cause of monogenic severe childhood-onset obesity. We confirmed the BMI association in 60,352 adults (per-allele effect = 0.05 Z-score units; P = 2.8 x 10(-15)) and 5,988 children aged 7-11 (0.13 Z-score units; P = 1.5 x 10(-8)). In case-control analyses (n = 10,583), the odds for severe childhood obesity reached 1.30 (P = 8.0 x 10(-11)). Furthermore, we observed overtransmission of the risk allele to obese offspring in 660 families (P (pedigree disequilibrium test average; PDT-avg) 2.4 x 10(-4)). The SNP location and patterns of phenotypic associations are consistent with effects mediated through altered MC4R function. Our findings establish that common variants near MC4R influence fat mass, weight and obesity risk at the population level and reinforce the need for large-scale data integration to identify variants influencing continuous biomedical traits.
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| 20. |
- Mootha, VK, et al.
(författare)
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PGC-1alpha-responsive genes involved in oxidative phosphorylation are coordinately downregulated in human diabetes.
- 2003
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 34:3, s. 267-273
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Tidskriftsartikel (refereegranskat)abstract
- DNA microarrays can be used to identify gene expression changes characteristic of human disease. This is challenging, however, when relevant differences are subtle at the level of individual genes. We introduce an analytical strategy, Gene Set Enrichment Analysis, designed to detect modest but coordinate changes in the expression of groups of functionally related genes. Using this approach, we identify a set of genes involved in oxidative phosphorylation whose expression is coordinately decreased in human diabetic muscle. Expression of these genes is high at sites of insulin-mediated glucose disposal, activated by PGC-1alpha and correlated with total-body aerobic capacity. Our results associate this gene set with clinically important variation in human metabolism and illustrate the value of pathway relationships in the analysis of genomic profiling experiments.
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