| 1. |
- Aydemir, Özkan, et al.
(author)
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Polymorphisms in Intron 1 of HLA-DRA Differentially Associate with Type 1 Diabetes and Celiac Disease and Implicate Involvement of Complement System Genes C4A and C4B
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In: eLife. - 2050-084X.
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Journal article (peer-reviewed)abstract
- Polymorphisms in genes in the human leukocyte antigen (HLA) class II region comprise the most important inherited risk factors for many autoimmune diseases including type 1 diabetes (T1D) and celiac disease (CD): both diseases are positively associated with the HLA- DR3 haplotype (DRB1*03:01-DQA1*05:01-DQB1*02:01). Studies of two different populations have recently documented that T1D susceptibility in HLA-DR3 homozygous individuals isstratified by a haplotype consisting of three single nucleotide polymorphisms (“tri-SNP”) in intron 1 of the HLA-DRA gene. In this study, we use a large cohort from the longitudinal “The Environmental Determinants of Diabetes in the Young” (TEDDY) study to further refine the tri-SNP association with T1D and with autoantibody-defined T1D endotypes. We found that the tri-SNP association is primarily in subjects whose first-appearing T1D autoantibody is to insulin. In addition, we discovered that the tri-SNP is also associated with celiac disease (CD), and that the particular tri-SNP haplotype (“101”) that is negatively associated with T1D risk is positively associated with risk for CD. The opposite effect of the tri-SNP haplotype on two DR3-associated diseases can enhance and refine current models of disease prediction based on genetic risk. Finally, we investigated possible functional differences between the individuals carrying high and low-risk tri-SNP haplotypes, and found that differences in complement system genes C4A and C4B may underlie the observed divergence in disease risk.
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| 2. |
- Dekker Nitert, Marloes, et al.
(author)
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Impact of an Exercise Intervention on DNA Methylation in Skeletal Muscle From First-Degree Relatives of Patients With Type 2 Diabetes.
- 2012
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In: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797.
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Journal article (peer-reviewed)abstract
- To identify epigenetic patterns, which may predispose to type 2 diabetes (T2D) due to a family history (FH) of the disease, we analyzed DNA methylation genome-wide in skeletal muscle from individuals with (FH(+)) or without (FH(-)) an FH of T2D. We found differential DNA methylation of genes in biological pathways including mitogen-activated protein kinase (MAPK), insulin, and calcium signaling (P ≤ 0.007) and of individual genes with known function in muscle, including MAPK1, MYO18B, HOXC6, and the AMP-activated protein kinase subunit PRKAB1 in skeletal muscle of FH(+) compared with FH(-) men. We further validated our findings from FH(+) men in monozygotic twin pairs discordant for T2D, and 40% of 65 analyzed genes exhibited differential DNA methylation in muscle of both FH(+) men and diabetic twins. We further examined if a 6-month exercise intervention modifies the genome-wide DNA methylation pattern in skeletal muscle of the FH(+) and FH(-) individuals. DNA methylation of genes in retinol metabolism and calcium signaling pathways (P < 3 × 10(-6)) and with known functions in muscle and T2D including MEF2A, RUNX1, NDUFC2, and THADA decreased after exercise. Methylation of these human promoter regions suppressed reporter gene expression in vitro. In addition, both expression and methylation of several genes, i.e., ADIPOR1, BDKRB2, and TRIB1, changed after exercise. These findings provide new insights into how genetic background and environment can alter the human epigenome.
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| 3. |
- Ekman, Carl, et al.
(author)
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Less pronounced response to exercise in healthy relatives to type 2 diabetic subjects compared with controls
- 2015
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In: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 119:9, s. 953-960
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Journal article (peer-reviewed)abstract
- Healthy first-degree relatives with heredity of type 2 diabetes (FH+) are known to have metabolic inflexibility compared with subjects without heredity for diabetes (FH-). In this study, we aimed to test the hypothesis that FH+ individuals have an impaired response to exercise compared with FH-. Sixteen FH+ and 19 FH- insulin-sensitive men similar in age, peak oxygen consumption ((V) over dot(O2 peak)), and body mass index completed an exercise intervention with heart rate monitored during exercise for 7 mo. Before and after the exercise intervention, the participants underwent a physical examination and tests for glucose tolerance and exercise capacity, and muscle biopsies were taken for expression analysis. The participants attended, on average, 39 training sessions during the intervention and spent 18.8 MJ on exercise. (V) over dot(O2 peak)/kg increased by 14%, and the participants lost 1.2 kg of weight and 3 cm waist circumference. Given that the FH- group expended 61% more energy during the intervention, we used regression analysis to analyze the response in the FH+ and FH- groups separately. Exercise volume had a significant effect on (V) over dot(O2 peak), weight, and waist circumference in the FH- group, but not in the FH+ group. After exercise, expression of genes involved in metabolism, oxidative phosphorylation, and cellular respiration increased more in the FH- compared with the FH+ group. This suggests that healthy, insulin-sensitive FH+ and FH- participants with similar age, (V) over dot(O2 peak), and body mass index may respond differently to an exercise intervention. The FH+ background might limit muscle adaptation to exercise, which may contribute to the increased susceptibility to type 2 diabetes in FH+ individuals.
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| 4. |
- Elgzyri, Targ, et al.
(author)
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First-degree relatives of type 2 diabetic patients have reduced expression of genes involved in fatty acid metabolism in skeletal muscle
- 2012
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In: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 97:7, s. E1332-E1337
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Journal article (peer-reviewed)abstract
- Context: First-degree relatives of patients with type 2 diabetes (FH+) have been shown to have decreased energy expenditure and decreased expression of mitochondrial genes in skeletal muscle. In previous studies, it has been difficult to distinguish whether mitochondrial dysfunction and differential regulation of genes are primary (genetic) or due to reduced physical activity, obesity, or other correlated factors.Objective: The aim of this study was to investigate whether mitochondrial dysfunction is a primary defect or results from an altered metabolic state.Design: We compared gene expression in skeletal muscle from 24 male subjects with FH and 26 without FH matched for age, glucose tolerance, VO2peak (peak oxygen uptake), and body mass index using microarrays. Additionally, type fiber composition, mitochondrial DNA content, and citrate synthase activity were measured. The results were followed up in an additional cohort with measurements of in vivo metabolism. Results: FH+ vs. FH- subjects showed reduced expression of mitochondrial genes (P = 2.75 x 10(-6)), particularly genes involved in fatty acid metabolism (P = 4.08 x 10(-7)), despite similar mitochondrial DNA content. Strikingly, a 70% reduced expression of the monoamine oxidase A(MAOA) gene was found in FH+ vs. FH- individuals (P = 0.0009). Down-regulation of the genes involved in fat metabolism was associated with decreased in vivo fat oxidation and increased glucose oxidation examined in an additional cohort of elderly men.Conclusions: These results suggest that genetically altered fatty acid metabolism predisposes to type 2 diabetes and propose a role for catecholamine-metabolizing enzymes like MAOA in the regulation of energy metabolism. (J Clin Endocrinol Metab 97: E1332-E1337, 2012)
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| 6. |
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| 7. |
- Johansson, Lovisa, et al.
(author)
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Differential gene expression in adipose tissue from obese human subjects during weight loss and weight maintenance.
- 2012
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In: The American journal of clinical nutrition. - : Elsevier BV. - 1938-3207 .- 0002-9165. ; 96:1, s. 196-207
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Journal article (peer-reviewed)abstract
- BACKGROUND: Differential gene expression in adipose tissue during diet-induced weight loss followed by a weight stability period is poorly characterized. Markers of these processes may provide a deeper understanding of underlying mechanisms. OBJECTIVE: We aimed to identify differentially expressed genes in human adipose tissue during weight loss and weight maintenance after weight loss. DESIGN: RNA from subcutaneous abdominal adipose tissue from 9 obese subjects was analyzed by using a complementary DNA microarray at baseline after weight loss on a low-calorie diet and after weight maintenance. RESULTS: Subjects lost 18.8 ± 1.8% of weight and maintained this loss during weight maintenance (1.1 ± 2.1%; range: -9.3 to 10.6%). Most differentially expressed genes exhibited a reciprocal regulation and returned to baseline after weight loss (2163 genes) and weight maintenance (3175 genes). CETP and ABCG1, both of which participate in the HDL-mediated reverse cholesterol transport (RCT), were among the most upregulated of the 750 genes that were differentially expressed after both processes. Several genes involved in inflammation were downregulated. The use of real-time polymerase chain reaction confirmed or partially confirmed the previously implicated genes TNMD and MMP9 (both downregulated), PNPLA3 (upregulated), and CIDEA and SCD (both reciprocally regulated). CONCLUSIONS: The beneficial effects of weight loss should be investigated after long-term weight maintenance. The processes of weight loss and weight maintenance should be viewed as biologically distinct. CETP and ABCG1 may be important mediators of these effects through HDL-mediated RCT.
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| 8. |
- Johansson, Lovisa, et al.
(author)
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Variation in the adiponutrin gene influences its expression and associates with obesity.
- 2006
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In: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 55:3, s. 826-833
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Journal article (peer-reviewed)abstract
- Adiponutrin is one of three recently identified adipocyte lipases. Surprisingly, these proteins also retain transacylase activity, a hitherto unknown pathway of triacylglycerol synthesis in the adipocytes. This may enable them to participate in both anabolic and catabolic processes. The adiponutrin gene (ADPN) is downregulated by fasting and upregulated by refeeding, suggesting a role in lipogenesis. Experiments in human adipocytes confirmed that the gene is upregulated in response to insulin in a glucose-dependent fashion. Obese subjects had increased levels of subcutaneous and visceral abdominal adipose tissue ADPN mRNA. Visceral ADPN mRNA expression was correlated to measures of insulin sensitivity (fasting insulin and homeostasis model assessment). We also studied genetic variation in ADPN and its relation to obesity, lipolysis, and mRNA expression. Two ADPN polymorphisms showed association with obesity. Carriers of the obesity-associated variants showed a lesser increase in the levels of adipose tissue ADPN mRNA and an increased basal lipolysis. Our results suggest that obese subjects that are insulin resistant and/or carriers of the obesity-associated ADPN alleles fail to upregulate the gene and that upregulation of adiponutrin may be an appropriate response to orchestrate energy excess.
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| 9. |
- Johnson, Suzanne Bennett, et al.
(author)
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First-appearing islet autoantibodies for type 1 diabetes in young children : maternal life events during pregnancy and the child's genetic risk
- 2021
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In: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 64:3, s. 591-602
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Journal article (peer-reviewed)abstract
- AIMS/HYPOTHESIS: Psychological stress has long been considered a possible trigger of type 1 diabetes, although prospective studies examining the link between psychological stress or life events during pregnancy and the child's type 1 diabetes risk are rare. The objective of this study was to examine the association between life events during pregnancy and first-appearing islet autoantibodies (IA) in young children, conditioned by the child's type 1 diabetes-related genetic risk.METHODS: The IA status of 7317 genetically at-risk The Environmental Determinants of Diabetes in the Young (TEDDY) participants was assessed every 3 months from 3 months to 4 years, and bi-annually thereafter. Reports of major life events during pregnancy were collected at study inception when the child was 3 months of age and placed into one of six categories. Life events during pregnancy were examined for association with first-appearing insulin (IAA) (N = 222) or GAD (GADA) (N = 209) autoantibodies in the child until 6 years of age using proportional hazard models. Relative excess risk due to interaction (RERI) by the child's HLA-DR and SNP profile was estimated.RESULTS: Overall, 65% of mothers reported a life event during pregnancy; disease/injury (25%), serious interpersonal (28%) and job-related (25%) life events were most common. The association of life events during pregnancy differed between IAA and GADA as the first-appearing autoantibody. Serious interpersonal life events correlated with increased risk of GADA-first only in HLA-DR3 children with the BACH2-T allele (HR 2.28, p < 0.0001), an additive interaction (RERI 1.87, p = 0.0004). Job-related life events were also associated with increased risk of GADA-first among HLA-DR3/4 children (HR 1.53, p = 0.04) independent of serious interpersonal life events (HR 1.90, p = 0.002), an additive interaction (RERI 1.19, p = 0.004). Job-related life events correlated with reduced risk of IAA-first (HR 0.55, p = 0.004), particularly in children with the BTNL2-GG allele (HR 0.48; 95% CI 0.31, 0.76).CONCLUSIONS/INTERPRETATION: Specific life events during pregnancy are differentially related to IAA vs GADA as first-appearing IA and interact with different HLA and non-HLA genetic factors, supporting the concept of different endotypes underlying type 1 diabetes. However, the mechanisms underlying these associations remain to be discovered. Life events may be markers for other yet-to-be-identified factors important to the development of first-appearing IA.
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| 10. |
- Koeck, Thomas, et al.
(author)
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A common variant in TFB1M is associated with reduced insulin secretion and increased future risk of type 2 diabetes.
- 2011
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In: Cell Metabolism. - : Elsevier BV. - 1550-4131 .- 1932-7420. ; 13:1, s. 80-91
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Journal article (peer-reviewed)abstract
- Type 2 diabetes (T2D) evolves when insulin secretion fails. Insulin release from the pancreatic β cell is controlled by mitochondrial metabolism, which translates fluctuations in blood glucose into metabolic coupling signals. We identified a common variant (rs950994) in the human transcription factor B1 mitochondrial (TFB1M) gene associated with reduced insulin secretion, elevated postprandial glucose levels, and future risk of T2D. Because islet TFB1M mRNA levels were lower in carriers of the risk allele and correlated with insulin secretion, we examined mice heterozygous for Tfb1m deficiency. These mice displayed lower expression of TFB1M in islets and impaired mitochondrial function and released less insulin in response to glucose in vivo and in vitro. Reducing TFB1M mRNA and protein in clonal β cells by RNA interference impaired complexes of the mitochondrial oxidative phosphorylation system. Consequently, nutrient-stimulated ATP generation was reduced, leading to perturbed insulin secretion. We conclude that a deficiency in TFB1M and impaired mitochondrial function contribute to the pathogenesis of T2D.
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