| 1. |
- Horikoshi, Momoko, et al.
(författare)
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New loci associated with birth weight identify genetic links between intrauterine growth and adult height and metabolism.
- 2013
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 45:1
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Tidskriftsartikel (refereegranskat)abstract
- Birth weight within the normal range is associated with a variety of adult-onset diseases, but the mechanisms behind these associations are poorly understood. Previous genome-wide association studies of birth weight identified a variant in the ADCY5 gene associated both with birth weight and type 2 diabetes and a second variant, near CCNL1, with no obvious link to adult traits. In an expanded genome-wide association meta-analysis and follow-up study of birth weight (of up to 69,308 individuals of European descent from 43 studies), we have now extended the number of loci associated at genome-wide significance to 7, accounting for a similar proportion of variance as maternal smoking. Five of the loci are known to be associated with other phenotypes: ADCY5 and CDKAL1 with type 2 diabetes, ADRB1 with adult blood pressure and HMGA2 and LCORL with adult height. Our findings highlight genetic links between fetal growth and postnatal growth and metabolism.
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| 2. |
- Fraga, MF, et al.
(författare)
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Epigenetic differences arise during the lifetime of monozygotic twins
- 2005
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 102:30, s. 10604-10609
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Tidskriftsartikel (refereegranskat)abstract
- Monozygous twins share a common genotype. However, most monozygotic twin pairs are not identical; several types of phenotypic discordance may be observed, such as differences in susceptibilities to disease and a wide range of anthropomorphic features. There are several possible explanations for these observations, but one is the existence of epigenetic differences. To address this issue, we examined the global and locus-specific differences in DNA methylation and histone acetylation of a large cohort of monozygotic twins. We found that, although twins are epigenetically indistinguishable during the early years of life, older monozygous twins exhibited remarkable differences in their overall content and genomic distribution of 5-methylcytosine DNA and histone acetylation, affecting their gene-expression portrait. These findings indicate how an appreciation of epigenetics is missing from our understanding of how different phenotypes can be originated from the same genotype.
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| 3. |
- Pilgaard, K., et al.
(författare)
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The T allele of rs7903146 TCF7L2 is associated with impaired insulinotropic action of incretin hormones, reduced 24 h profiles of plasma insulin and glucagon, and increased hepatic glucose production in young healthy men
- 2009
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 52:7, s. 1298-1307
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Tidskriftsartikel (refereegranskat)abstract
- We studied the physiological, metabolic and hormonal mechanisms underlying the elevated risk of type 2 diabetes in carriers of TCF7L2 gene. We undertook genotyping of 81 healthy young Danish men for rs7903146 of TCF7L2 and carried out various beta cell tests including: 24 h glucose, insulin and glucagon profiles; OGTT; mixed meal test; IVGTT; hyperglycaemic clamp with co-infusion of glucagon-like peptide (GLP)-1 or glucose-dependent insulinotropic polypeptide (GIP); and a euglycaemic-hyperinsulinaemic clamp combined with glucose tracer infusion to study hepatic and peripheral insulin action. Carriers of the T allele were characterised by reduced 24 h insulin concentrations (p < 0.05) and reduced insulin secretion relative to glucose during a mixed meal test (beta index: p < 0.003), but not during an IVGTT. This was further supported by reduced late-phase insulinotropic action of GLP-1 (p = 0.03) and GIP (p = 0.07) during a 7 mmol/l hyperglycaemic clamp. Secretion of GLP-1 and GIP during the mixed meal test was normal. Despite elevated hepatic glucose production, carriers of the T allele had significantly reduced 24 h glucagon concentrations (p < 0.02) suggesting altered alpha cell function. Elevated hepatic glucose production and reduced insulinotropic effect of incretin hormones contribute to an increased risk of type 2 diabetes in carriers of the rs7903146 risk T allele of TCF7L2.
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| 4. |
- Arora, G. P., et al.
(författare)
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Insulin secretion and action in North Indian women during pregnancy
- 2017
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Ingår i: Diabetic Medicine: A journal of the British Diabetic Association. - : Wiley. - 1464-5491. ; 34:10, s. 1477-1482
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Tidskriftsartikel (refereegranskat)abstract
- AIM: The relative roles(s) of impaired insulin secretion vs. insulin resistance in the development of gestational diabetes mellitus depend upon multiple risk factors and diagnostic criteria. Here, we explored their relative contribution to gestational diabetes as defined by the WHO 1999 (GDM1999) and adapted WHO 2013 (GDM2013) criteria, excluding the 1-h glucose value, in a high-risk Indian population from Punjab.METHODS: Insulin secretion (HOMA2-B) and insulin action (HOMA2-IR) were assessed in 4665 Indian women with or without gestational diabetes defined by the GDM1999 or adapted GDM2013 criteria.RESULTS: Gestational diabetes defined using both criteria was associated with decreased insulin secretion compared with pregnant women with normal glucose tolerance. Women with gestational diabetes defined by the adapted GDM2013, but not GDM1999 criteria, were more insulin resistant than pregnant women with normal glucose tolerance, and furthermore displayed lower insulin secretion than GDM1999 women. Urban habitat, illiteracy, high age and low BMI were independently associated with reduced insulin secretion, whereas Sikh religion, increasing age and BMI, as well as a family history of diabetes were independently associated with increased insulin resistance.CONCLUSIONS: Gestational diabetes risk factors influence insulin secretion and action in North Indian women in a differential manner. Gestational diabetes classified using the adapted GDM2013 compared with GDM1999 criteria is associated with more severe impairments of insulin secretion and action.
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| 5. |
- Cardona, Alexia, et al.
(författare)
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Epigenome-wide association study of incident type 2 diabetes in a British population : EPIC-Norfolk study
- 2019
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 68:12, s. 2315-2326
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Tidskriftsartikel (refereegranskat)abstract
- Epigenetic changes may contribute substantially to risks of diseases of aging. Previous studies reported seven methylation variable positions (MVPs) robustly associated with incident type 2 diabetes mellitus (T2DM). However, their causal roles in T2DM are unclear. In an incident T2DM case-cohort study nested within the populationbased European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk cohort, we used whole blood DNA collected at baseline, up to 11 years before T2DM onset, to investigate the role of methylation in the etiology of T2DM. We identified 15 novel MVPs with robust associations with incident T2DM and robustly confirmed three MVPs identified previously (near to TXNIP, ABCG1, and SREBF1). All 18 MVPs showed directionally consistent associations with incident and prevalent T2DM in independent studies. Further conditional analyses suggested that the identified epigenetic signals appear related to T2DM via glucose and obesityrelated pathways acting before the collection of baseline samples.We integrated genome-wide genetic data to identify methylation-associated quantitative trait loci robustly associated with 16 of the 18 MVPs and found one MVP, cg00574958 at CPT1A, with a possible direct causal role in T2DM. None of the implicated genes were previously highlighted by genetic association studies, suggesting that DNA methylation studies may reveal novel biological mechanisms involved in tissue responses to glycemia.
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| 6. |
- Davegårdh, Cajsa, et al.
(författare)
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Abnormal epigenetic changes during differentiation of human skeletal muscle stem cells from obese subjects
- 2017
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Ingår i: BMC Medicine. - : Springer Science and Business Media LLC. - 1741-7015. ; 15:1, s. 1-27
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Tidskriftsartikel (refereegranskat)abstract
- Background: Human skeletal muscle stem cells are important for muscle regeneration. However, the combined genome-wide DNA methylation and expression changes taking place during adult myogenesis have not been described in detail and novel myogenic factors may be discovered. Additionally, obesity is associated with low relative muscle mass and diminished metabolism. Epigenetic alterations taking place during myogenesis might contribute to these defects. Methods: We used Infinium HumanMethylation450 BeadChip Kit (Illumina) and HumanHT-12 Expression BeadChip (Illumina) to analyze genome-wide DNA methylation and transcription before versus after differentiation of primary human myoblasts from 14 non-obese and 14 obese individuals. Functional follow-up experiments were performed using siRNA mediated gene silencing in primary human myoblasts and a transgenic mouse model. Results: We observed genome-wide changes in DNA methylation and expression patterns during differentiation of primary human muscle stem cells (myoblasts). We identified epigenetic and transcriptional changes of myogenic transcription factors (MYOD1, MYOG, MYF5, MYF6, PAX7, MEF2A, MEF2C, and MEF2D), cell cycle regulators, metabolic enzymes and genes previously not linked to myogenesis, including IL32, metallothioneins, and pregnancy-specific beta-1-glycoproteins. Functional studies demonstrated IL-32 as a novel target that regulates human myogenesis, insulin sensitivity and ATP levels in muscle cells. Furthermore, IL32 transgenic mice had reduced insulin response and muscle weight. Remarkably, approximately 3.7 times more methylation changes (147,161 versus 39,572) were observed during differentiation of myoblasts from obese versus non-obese subjects. In accordance, DNMT1 expression increased during myogenesis only in obese subjects. Interestingly, numerous genes implicated in metabolic diseases and epigenetic regulation showed differential methylation and expression during differentiation only in obese subjects. Conclusions: Our study identifies IL-32 as a novel myogenic regulator, provides a comprehensive map of the dynamic epigenome during differentiation of human muscle stem cells and reveals abnormal epigenetic changes in obesity.
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| 7. |
- Hatem, Gad, et al.
(författare)
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Mapping the cord blood transcriptome of pregnancies affected by early maternal anemia to identify signatures of fetal programming
- 2022
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 107:5, s. 1303-1316
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Anemia during early pregnancy (EP) is common in developing countries and is associated with adverse health consequences for both mother and children. Offspring of women with EP anemia often have low birth-weight, the latter being a risk factor for cardiometabolic diseases including type 2 diabetes (T2D) later in life. Mechanisms underlying developmental programming of adult cardiometabolic disease include epigenetic and transcriptional alterations potentially detectable in umbilical cord blood (UCB) at time of birth.METHODS: We leveraged global transcriptome- and accompanying epigenome-wide changes in 48 UCB from newborns of EP-anemic Tanzanian mothers and 50 controls to identify differentially expressed genes (DEG) in UCB exposed to maternal EP-anemia. DEGs were assessed for association with neonatal anthropometry and cord insulin levels. These genes were further studied in expression data from human fetal pancreas and adult islets to understand their role in beta-cell development and/or function.RESULTS: The expression of 137 genes was altered in UCB of newborns exposed to maternal EP anemia. These putative signatures of fetal programming which included the birth-weight locus LCORL, were potentially mediated by epigenetic changes in 27 genes and associated with neonatal anthropometry. Among the DEGs were P2RX7, PIK3C2B, and NUMBL which potentially influence beta-cell development. Insulin levels were lower in EP anemia exposed UCB, supporting the notion of developmental programming of pancreatic beta-cell dysfunction and subsequently increased risk of T2D in offspring of EP anemic mothers.CONCLUSIONS: Our data provide proof-of-concept on distinct transcriptional and epigenetic changes detectable in UCB from newborns exposed to maternal EP anemia.
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| 8. |
- Jacobsen, S. C., et al.
(författare)
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Effects of short-term high-fat overfeeding on genome-wide DNA methylation in the skeletal muscle of healthy young men
- 2012
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 55:12, s. 3341-3349
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Tidskriftsartikel (refereegranskat)abstract
- Energy-dense diets that are high in fat are associated with a risk of metabolic diseases. The underlying molecular mechanisms could involve epigenetics, as recent data show altered DNA methylation of putative type 2 diabetes candidate genes in response to high-fat diets. We examined the effect of a short-term high-fat overfeeding (HFO) diet on genome-wide DNA methylation patterns in human skeletal muscle. Skeletal muscle biopsies were obtained from 21 healthy young men after ingestion of a short-term HFO diet and a control diet, in a randomised crossover setting. DNA methylation was measured in 27,578 CpG sites/14,475 genes using Illumina's Infinium Bead Array. Candidate gene expression was determined by quantitative real-time PCR. HFO introduced widespread DNA methylation changes affecting 6,508 genes (45%), with a maximum methylation change of 13.0 percentage points. The HFO-induced methylation changes were only partly and non-significantly reversed after 6-8 weeks. Alterations in DNA methylation levels primarily affected genes involved in inflammation, the reproductive system and cancer. Few gene expression changes were observed and these had poor correlation to DNA methylation. The genome-wide DNA methylation changes induced by the short-term HFO diet could have implications for our understanding of transient epigenetic regulation in humans and its contribution to the development of metabolic diseases. The slow reversibility suggests a methylation build-up with HFO, which over time may influence gene expression levels.
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| 9. |
- Kurucz, I, et al.
(författare)
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Decreased expression of heat shock protein 72 in skeletal muscle of patients with type 2 diabetes correlates with insulin resistance
- 2002
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Ingår i: Diabetes. - 1939-327X. ; 51:4, s. 1102-1109
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Tidskriftsartikel (refereegranskat)abstract
- Oxidative stress has been ascribed a role in the pathogenesis of diabetes and its complications, and stress proteins have been shown to protect organisms in vitro and in vivo against oxidative stress. To study the putative role of one of the most abundant cytoprotective stress proteins, inducible cytoplasmic 72-kDa-mass heat shock protein (Hsp-72), in the pathogenesis of diabetes, we measured its mRNA concentration in muscle biopsies from six type 2 diabetic patients and six healthy control subjects (protocol 1) as well as in 12 twin pairs discordant for type 2 diabetes and 12 control subjects undergoing a euglycemic-hyperinsulinemic clamp in combination with indirect calorimetry (protocol 2). The amount of Hsp-72 mRNA in muscle was significantly lower in type 2 diabetic patients than in healthy control subjects (in protocol 1: 5.2 +/- 2.2 vs. 53 +/- 32 million copies of Hsp-72 mRNA/mug total RNA, n = 6, P = 0.0039; in protocol 2: 3.2 +/- 3.3 vs. 43 +/- 31 million copies of Hsp-72 mRNA/mug total RNA, n = 12, P = 0.0001). Hsp-72 mRNA levels were also markedly reduced in the nondiabetic co-twins compared with healthy control subjects (5.8 +/- 5.0 vs. 43 +/- 31, n = 12, P = 0.0001), but they were also statistically significantly different from their diabetic co-twins when the difference between the pairs was compared (P = 0.0280). Heat shock protein mRNA content in muscle of examined patients correlated with the rate of glucose uptake and other measures of insulin-stimulated carbohydrate and lipid metabolism. In conclusion, the finding of decreased levels of Hsp-72 mRNA in skeletal muscle of patients with type 2 diabetes and its relationship with insulin resistance raises the question of whether heat shock proteins are involved in the pathogenesis of skeletal muscle insulin resistance in type 2 diabetes.
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| 10. |
- Lund, S. S., et al.
(författare)
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Effect of adjunct metformin treatment on levels of plasma lipids in patients with type 1 diabetes
- 2009
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Ingår i: Diabetes, Obesity and Metabolism. - : Wiley. - 1462-8902 .- 1463-1326. ; 11:10, s. 966-977
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Tidskriftsartikel (refereegranskat)abstract
- Background In addition to its glucose-lowering effect, metformin treatment has been suggested to improve lipidaemia in patients with type 2 diabetes. In contrast, in patients with type 1 diabetes (T1DM), information about the effect of metformin treatment on lipidaemia is limited. In this study, we report the effect of a 1-year treatment with metformin vs. placebo on plasma lipids in T1DM patients and persistent poor glycaemic control. Methods One hundred T1DM patients with haemoglobinA(1c) (HbA(1c)) >= 8.5% during the year before enrolment entered a 1-month run-in period on placebo treatment. Thereafter, patients were randomized (baseline) to treatment with either metformin (1000 mg twice daily) or placebo for 12 months (double masked). Patients continued ongoing insulin therapy and their usual outpatient clinical care. Outcomes were assessed at baseline and after 1 year. Results After 1 year, in those patients who did not start or stop statin therapy during the trial, metformin treatment significantly reduced total and LDL cholesterol by approximately 0.3 mmol/l compared with placebo (p = 0.021 and p = 0.018 respectively). Adjustment for statin use or known cardiovascular disease did not change conclusions. In statin users (metformin: n = 22, placebo: n = 13), metformin significantly lowered levels of LDL and non-HDL cholesterol by approximately 0.5 mmol/l compared with placebo (adjusted for changes in statin dose or agent: p = 0.048 and p = 0.033 respectively). HbA(1c) (previously reported) was not significant different between treatments. Conclusion In patients with poorly controlled T1DM, at similar glycaemic levels, adjunct metformin therapy during 1 year significantly lowered levels of proatherogenic cholesterolaemia independent of statin therapy.
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