| 1. |
- Wang, Z., et al.
(author)
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Genome-wide association analyses of physical activity and sedentary behavior provide insights into underlying mechanisms and roles in disease prevention
- 2022
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 54:9, s. 1332-1344
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Journal article (peer-reviewed)abstract
- Although physical activity and sedentary behavior are moderately heritable, little is known about the mechanisms that influence these traits. Combining data for up to 703,901 individuals from 51 studies in a multi-ancestry meta-analysis of genome-wide association studies yields 99 loci that associate with self-reported moderate-to-vigorous intensity physical activity during leisure time (MVPA), leisure screen time (LST) and/or sedentary behavior at work. Loci associated with LST are enriched for genes whose expression in skeletal muscle is altered by resistance training. A missense variant in ACTN3 makes the alpha-actinin-3 filaments more flexible, resulting in lower maximal force in isolated type IIA muscle fibers, and possibly protection from exercise-induced muscle damage. Finally, Mendelian randomization analyses show that beneficial effects of lower LST and higher MVPA on several risk factors and diseases are mediated or confounded by body mass index (BMI). Our results provide insights into physical activity mechanisms and its role in disease prevention. Multi-ancestry meta-analyses of genome-wide association studies for self-reported physical activity during leisure time, leisure screen time, sedentary commuting and sedentary behavior at work identify 99 loci associated with at least one of these traits.
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| 2. |
- Barres, R., et al.
(author)
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Acute exercise remodels promoter methylation in human skeletal muscle
- 2012
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In: Cell Metabolism. - : Elsevier BV. - 1550-4131 .- 1932-7420. ; 15:3, s. 405-11
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Journal article (peer-reviewed)abstract
- DNA methylation is a covalent biochemical modification controlling chromatin structure and gene expression. Exercise elicits gene expression changes that trigger structural and metabolic adaptations in skeletal muscle. We determined whether DNA methylation plays a role in exercise-induced gene expression. Whole genome methylation was decreased in skeletal muscle biopsies obtained from healthy sedentary men and women after acute exercise. Exercise induced a dose-dependent expression of PGC-1alpha, PDK4, and PPAR-delta, together with a marked hypomethylation on each respective promoter. Similarly, promoter methylation of PGC-1alpha, PDK4, and PPAR-delta was markedly decreased in mouse soleus muscles 45 min after ex vivo contraction. In L6 myotubes, caffeine exposure induced gene hypomethylation in parallel with an increase in the respective mRNA content. Collectively, our results provide evidence that acute gene activation is associated with a dynamic change in DNA methylation in skeletal muscle and suggest that DNA hypomethylation is an early event in contraction-induced gene activation.
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| 3. |
- Al-Khalili, Lubna, et al.
(author)
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Profiling of human myotubes reveals an intrinsic proteomic signature associated with type 2 diabetes
- 2014
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In: Translational Proteomics. - : Elsevier BV. - 2212-9634 .- 2212-9626. ; 2:1, s. 25-38
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Journal article (peer-reviewed)abstract
- The development of insulin resistance and type 2 diabetes (T2D) involves a complex array of metabolic defects in skeletal muscle. An in vitro cell culture system excludes the acute effects of external systemic factors existing in vivo. Thus, we aimed to determine whether intrinsic differences in the protein profile exist in cultured myotubes derived from T2D versus normal glucose tolerant (NGT) healthy people. Applying two dimensional difference gel electrophoresis technology (2-D DIGE), the abundance of 47 proteins differed in myotubes derived from T2D patients versus NGT donors. Proteins involved in fatty acid and amino acid metabolism, TCA cycle, mitochondrial function, mRNA processing, DNA repair and cell survival showed higher abundance, while proteins associated with redox signaling (PARK7; Parkinson disease 7), glutathione metabolism (glutathione S-transferase, GST, isoforms T1, P1 and M2), and protein dynamics (heat shock protein, HSP, isoform B1 and 90A) showed reduced abundance in myotubes derived from T2D versus NGT donors. Consistent with our proteome analysis results, the level of total glutathione was reduced in myotubes obtained from T2D versus NGT donors. Taken together, our data provide evidence for intrinsic differences in the profile of proteins involved in energy metabolism, cellular oxidative stress, protein dynamics and gene regulation in myotubes derived from T2D patients. These differences thereby suggest a genetic or epigenetic influence on protein content level, which can be further investigated to understand the molecular underpinnings of T2D progression and lead to new therapeutic approaches.
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| 4. |
- Barres, R., et al.
(author)
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Non-CpG methylation of the PGC-1alpha promoter through DNMT3B controls mitochondrial density
- 2009
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In: Cell Metabolism. - : Elsevier BV. - 1550-4131 .- 1932-7420. ; 10:3, s. 189-98
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Journal article (peer-reviewed)abstract
- Epigenetic modification through DNA methylation is implicated in metabolic disease. Using whole-genome promoter methylation analysis of skeletal muscle from normal glucose-tolerant and type 2 diabetic subjects, we identified cytosine hypermethylation of peroxisome proliferator-activated receptor gamma (PPARgamma) coactivator-1 alpha (PGC-1alpha) in diabetic subjects. Methylation levels were negatively correlated with PGC-1alpha mRNA and mitochondrial DNA (mtDNA). Bisulfite sequencing revealed that the highest proportion of cytosine methylation within PGC-1alpha was found within non-CpG nucleotides. Non-CpG methylation was acutely increased in human myotubes by exposure to tumor necrosis factor-alpha (TNF-alpha) or free fatty acids, but not insulin or glucose. Selective silencing of the DNA methyltransferase 3B (DNMT3B), but not DNMT1 or DNMT3A, prevented palmitate-induced non-CpG methylation of PGC-1alpha and decreased mtDNA and PGC-1alpha mRNA. We provide evidence for PGC-1alpha hypermethylation, concomitant with reduced mitochondrial content in type 2 diabetic patients, and link DNMT3B to the acute fatty-acid-induced non-CpG methylation of PGC-1alpha promoter.
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| 5. |
- Czepluch, F. S., et al.
(author)
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Strenuous physical exercise adversely affects monocyte chemotaxis
- 2011
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In: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 105:1, s. 122-30
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Journal article (peer-reviewed)abstract
- Physical exercise is important for proper cardiovascular function and disease prevention, but it may influence the immune system. We evaluated the effect of strenuous exercise on monocyte chemotaxis. Monocytes were isolated from blood of 13 young, healthy, sedentary individuals participating in a three-week training program which consisted of repeated exercise bouts. Monocyte chemotaxis and serological biomarkers were investigated at baseline, after three weeks training and after four weeks recovery. Chemotaxis towards vascular endothelial growth factor-A (VEGF-A) and transforming growth factor-beta1 (TGF-beta1) was completely inhibited immediately after training (p<0.01), and remained so after four weeks recovery. Likewise, monocyte chemoattractant protein-1 (MCP-1)-induced migration declined after training (p<0.01) and improved only partially during the recovery period. MCP-1 serum levels were significantly reduced after four weeks recovery compared to baseline (p<0.01). Total blood antioxidant capacity was enhanced at this time point (p<0.01). Monocyte chemokinesis, TGF-beta1 and nitric oxide serum levels remained unchanged during the study. Strenuous three-week training consisting of repeated exercise bouts in healthy, sedentary individuals reduces monocyte chemotaxis. It remains to be established, whether this is a sound adaptation to increased stimuli or an untoward reaction to overtraining. Nevertheless, the effect remains for several weeks with no exercise.
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| 6. |
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| 7. |
- Lundholm, L, et al.
(author)
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The estrogen receptor {alpha}-selective agonist propyl pyrazole triol improves glucose tolerance in ob/ob mice; potential molecular mechanisms
- 2008
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In: Journal of Endocrinology. - 0022-0795 .- 1479-6805. ; 199:2, s. 275-286
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Journal article (peer-reviewed)abstract
- The aim of this study was to validate the role of estrogen receptor alpha (ERalpha) signaling in the regulation of glucose metabolism, and to compare the molecular events upon treatment with the ERalpha-selective agonist propyl pyrazole triol (PPT) or 17beta-estradiol (E(2)) in ob/ob mice. Female ob/ob mice were treated with PPT, E(2) or vehicle for 7 or 30 days. Intraperitoneal glucose and insulin tolerance tests were performed, and insulin secretion was determined from isolated islets. Glucose uptake was assayed in isolated skeletal muscle and adipocytes. Gene expression profiling in the liver was performed using Affymetrix microarrays, and the expression of selected genes was studied by real-time PCR analysis. PPT and E(2) treatment improved glucose tolerance and insulin sensitivity. Fasting blood glucose levels decreased after 30 days of PPT and E(2) treatment. However, PPT and E(2) had no effect on insulin secretion from isolated islets. Basal and insulin-stimulated glucose uptake in skeletal muscle and adipose tissue were similar in PPT and vehicle-treated ob/ob mice. Hepatic lipid content was decreased after E(2) treatment. In the liver, treatment with E(2) and PPT increased and decreased the respective expression levels of the transcription factor signal transducer and activator of transcription 3, and of glucose-6-phosphatase. In summary, our data demonstrate that PPT exerts anti-diabetic effects, and these effects are mediated via ERalpha.
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| 8. |
- Stanford, K, et al.
(author)
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Exercise Metabolism
- 2017
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In: Cell metabolism. - : Elsevier BV. - 1932-7420 .- 1550-4131. ; 25:5, s. 978-984
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Journal article (peer-reviewed)
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Borg, ML, et al.
(author)
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Modified UCN2 Peptide Acts as an Insulin Sensitizer in Skeletal Muscle of Obese Mice
- 2019
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In: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 68:7, s. 1403-1414
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Journal article (peer-reviewed)abstract
- The neuropeptide urocortin 2 (UCN2) and its receptor corticotropin-releasing hormone receptor 2 (CRHR2) are highly expressed in skeletal muscle and play a role in regulating energy balance and glucose metabolism. We investigated a modified UCN2 peptide as a potential therapeutic agent for the treatment of obesity and insulin resistance, with a specific focus on skeletal muscle. High-fat–fed mice (C57BL/6J) were injected daily with a PEGylated UCN2 peptide (compound A) at 0.3 mg/kg subcutaneously for 14 days. Compound A reduced body weight, food intake, whole-body fat mass, and intramuscular triglycerides compared with vehicle-treated controls. Furthermore, whole-body glucose tolerance was improved by compound A treatment, with increased insulin-stimulated Akt phosphorylation at Ser473 and Thr308 in skeletal muscle, concomitant with increased glucose transport into extensor digitorum longus and gastrocnemius muscle. Mechanistically, this is linked to a direct effect on skeletal muscle because ex vivo exposure of soleus muscle from chow-fed lean mice to compound A increased glucose transport and insulin signaling. Moreover, exposure of GLUT4-Myc–labeled L6 myoblasts to compound A increased GLUT4 trafficking. Our results demonstrate that modified UCN2 peptides may be efficacious in the treatment of type 2 diabetes by acting as an insulin sensitizer in skeletal muscle.
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| 13. |
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| 14. |
- Fakhrai-Rad, H, et al.
(author)
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Insulin-degrading enzyme identified as a candidate diabetes susceptibility gene in GK rats.
- 2000
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In: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 9:14, s. 2149-58
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Journal article (peer-reviewed)abstract
- Genetic analysis of the diabetic GK rat has revealed several diabetes susceptibility loci. Congenic strains have been established for the major diabetes locus, Niddm1, by transfer of GK alleles onto the genome of the normoglycemic F344 rat. Niddm1 was dissected into two subloci, physically separated in the congenic strains Niddm1b and Niddm1i, each with at least one disease susceptibility gene. Here we have mapped Niddm1b to 1 cM by genetic and pathophysiological characterization of new congenic substrains for the locus. The gene encoding insulin-degrading enzyme (IDE:) was located to this 1 cM region, and the two amino acid substitutions (H18R and A890V) identified in the GK allele reduced insulin-degrading activity by 31% in transfected cells. However, when the H18R and A890V variants were studied separately, no effects were observed, demonstrating a synergistic effect of the two variants on insulin degradation. No effect on insulin degradation was observed in cell lysates, indicating that the effect is coupled to receptor-mediated internalization of insulin. Congenic rats with the IDE: GK allele displayed post-prandial hyperglycemia, reduced lipogenesis in fat cells, blunted insulin-stimulated glucose transmembrane uptake and reduced insulin degradation in isolated muscle. Analysis of additional rat strains demonstrated that the dysfunctional IDE: allele was unique to GK. These data point to an important role for IDE: in the diabetic phenotype in GK.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Ring, M., et al.
(author)
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Influence of physical activity and gender on arterial function in type 2 diabetes, normal and impaired glucose tolerance
- 2015
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In: Diabetes & Vascular Disease Research. - : SAGE Publications. - 1479-1641 .- 1752-8984. ; 12:5, s. 315-324
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Journal article (peer-reviewed)abstract
- To determine whether Nordic walking improves cardiovascular function in middle-aged women and men, we included 121 with normal glucose tolerance, 33 with impaired glucose tolerance and 47 with Type 2 diabetes mellitus in a randomized controlled study. The intervention group added Nordic walking 5h/week for 4months to their ordinary activities. Aortic pulse wave velocity, aortic augmentation index, stiffness index, reflection index, intima-media thickness in the radial and carotid arteries, echogenicity of the carotid intima-media and systemic vascular resistance were measured. While baseline blood pressure did not differ by gender or diagnosis, aortic augmentation index was found to be higher in women in all groups. Vascular function was unchanged with intervention, without differences by gender or diagnosis. In conclusion, 4months of Nordic walking is an insufficient stimulus to improve vascular function. Future studies should consider hard endpoints in addition to measures of vascular health, as well as larger population groups, long-term follow-up and documented compliance to exercise training.
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| 19. |
- Sjögren, Rasmus J. O., et al.
(author)
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Branched-chain amino acid metabolism is regulated by ERRα in primary human myotubes and is further impaired by glucose loading in type 2 diabetes
- 2021
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In: Diabetologia. - : Springer. - 0012-186X .- 1432-0428. ; 64:9, s. 2077-2091
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Journal article (peer-reviewed)abstract
- Aims/hypothesis: Increased levels of branched-chain amino acids (BCAAs) are associated with type 2 diabetes pathogenesis. However, most metabolomic studies are limited to an analysis of plasma metabolites under fasting conditions, rather than the dynamic shift in response to a metabolic challenge. Moreover, metabolomic profiles of peripheral tissues involved in glucose homeostasis are scarce and the transcriptomic regulation of genes involved in BCAA catabolism is partially unknown. This study aimed to identify differences in circulating and skeletal muscle BCAA levels in response to an OGTT in individuals with normal glucose tolerance (NGT) or type 2 diabetes. Additionally, transcription factors involved in the regulation of the BCAA gene set were identified.Methods: Plasma and vastus lateralis muscle biopsies were obtained from individuals with NGT or type 2 diabetes before and after an OGTT. Plasma and quadriceps muscles were harvested from skeletal muscle-specific Ppargc1a knockout and transgenic mice. BCAA-related metabolites and genes were assessed by LC-MS/MS and quantitative RT-PCR, respectively. Small interfering RNA and adenovirus-mediated overexpression techniques were used in primary human skeletal muscle cells to study the role of PPARGC1A and ESRRA in the expression of the BCAA gene set. Radiolabelled leucine was used to analyse the impact of oestrogen-related receptor α (ERRα) knockdown on leucine oxidation.Results: Impairments in BCAA catabolism in people with type 2 diabetes under fasting conditions were exacerbated after a glucose load. Branched-chain keto acids were reduced 37–56% after an OGTT in the NGT group, whereas no changes were detected in individuals with type 2 diabetes. These changes were concomitant with a stronger correlation with glucose homeostasis biomarkers and downregulated expression of branched-chain amino acid transaminase 2, branched-chain keto acid dehydrogenase complex subunits and 69% of downstream BCAA-related genes in skeletal muscle. In primary human myotubes overexpressing peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α, encoded by PPARGC1A), 61% of the analysed BCAA genes were upregulated, while 67% were downregulated in the quadriceps of skeletal muscle-specific Ppargc1a knockout mice. ESRRA (encoding ERRα) silencing completely abrogated the PGC-1α-induced upregulation of BCAA-related genes in primary human myotubes. Conclusions/interpretation: Metabolic inflexibility in type 2 diabetes impacts BCAA homeostasis and attenuates the decrease in circulating and skeletal muscle BCAA-related metabolites after a glucose challenge. Transcriptional regulation of BCAA genes in primary human myotubes via PGC-1α is ERRα-dependent. Graphical abstract: [Figure not available: see fulltext.]
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| 20. |
- Song, X M, et al.
(author)
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5-Aminoimidazole-4-carboxamide ribonucleoside treatment improves glucose homeostasis in insulin-resistant diabetic (ob/ob) mice.
- 2002
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In: Diabetologia. - 0012-186X .- 1432-0428. ; 45:1, s. 56-65
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Journal article (peer-reviewed)abstract
- AIMS/HYPOTHESIS: The 5'AMP-activated protein kinase is an important mediator of muscle contraction-induced glucose transport and a target for pharmacological treatment of Type II (non-insulin-dependent) diabetes mellitus. The 5'AMP-activated protein kinase can be activated by 5-aminoimidazole-4-carboxamide ribonucleoside. We hypothesised that 5-aminoimidazole-4-carboxamide ribonucleoside treatment could restore glucose homeostasis in ob/ob mice.METHODS: Lean and ob/ob mice were given 5-aminoimidazole-4-carboxamide ribonucleoside (1 mg.g body wt(-1).day(-1) s.c) or 0.9 % NaCl (vehicle) for 1-7 days.RESULTS: Short-term 5-aminoimidazole-4-carboxamide ribonucleoside treatment normalised glucose concentrations in ob/ob mice within 1 h, with effects persisting over 4 h. After 1 week of daily injections, 5-aminoimidazole-4-carboxamide ribonucleoside treatment corrected hyperglycaemia, improved glucose tolerance, and increased GLUT4 and hexokinase II protein expression in skeletal muscle, but had deleterious effects on plasma non-esterified fatty acids and triglycerides. Treatment with 5-aminoimidazole-4-carboxamide ribonucleoside increased liver glycogen in fasted and fed ob/ob mice and muscle glycogen in fasted, but not fed ob/ob and lean mice. Defects in insulin-stimulated phosphatidylinositol 3-kinase and glucose transport in skeletal muscle from ob/ob mice were not corrected by 5-aminoimidazole-4-carboxamide ribonucleoside treatment. While ex vivo insulin-stimulated glucose transport was reduced in isolated muscle from ob/ob mice, the 5-aminoimidazole-4-carboxamide ribonucleoside stimulated response was normal.CONCLUSION/INTERPRETATION: The 5-aminoimidazole-4-carboxamide ribonucleoside mediated improvements in glucose homeostasis in ob/ob mice can be explained by effects in skeletal muscle and liver. Due to the apparently deleterious effects of 5-aminoimidazole-4-carboxamide ribonucleoside on the blood lipid profile, strategies to develop tissue-specific and pathway-specific activators of 5'AMP-activated protein kinase should be considered in order to improve glucose homeostasis.
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| 21. |
- Sultan, A., et al.
(author)
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T cell-mediated inflammation in adipose tissue does not cause insulin resistance in hyperlipidemic mice
- 2009
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In: Circ Res. - 1524-4571 .- 0009-7330. ; 104:8, s. 961-8
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Journal article (peer-reviewed)abstract
- Obesity is associated with chronic inflammation in adipose tissue. Proinflammatory cytokines including tumor necrosis factor-alpha and interleukin-6 secreted by adipose tissue during the metabolic syndrome are proposed to cause local and general insulin resistance and promote development of type 2 diabetes. We have used a compound mutant mouse, Apoe(-/-)xCD4dnTGFbR, with dysregulation of T-cell activation, excessive production of proinflammatory cytokines, hyperlipidemia, and atherosclerosis, to dissect the role of inflammation in adipose tissue metabolism. These mice are lean, which avoids confounding effects of concomitant obesity. Expression and secretion of a set of proinflammatory factors including tumor necrosis factor-alpha, interferon-gamma, and monocyte chemoattractant protein-1 was increased in adipose tissue of Apoe(-/-)xCD4dnTGFbR mice, as was the enzyme 11beta-hydroxysteroid dehydrogenase type 1, which converts cortisone to bioactive cortisol. Interleukin-6, which has an inhibitory glucocorticoid response element in its promoter, was not upregulated. In spite of intense local inflammation, insulin sensitivity was not impaired in adipose tissue of Apoe(-/-)xCD4dnTGFbR mice unless exogenous interleukin-6 was administered. In conclusion, T-cell activation causes inflammation in adipose tissue but does not lead to insulin resistance in this tissue in the absence of interleukin-6.
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| 22. |
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| 23. |
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| 24. |
- Boon, Hanneke, 1981-, et al.
(author)
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MicroRNA-208b progressively declines after spinal cord injury in humans and is inversely related to myostatin expression
- 2015
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In: Physiological Reports. - Chichester : John Wiley & Sons. - 2051-817X. ; 3:11
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Journal article (peer-reviewed)abstract
- The effects of long‐term physical inactivity on the expression of microRNAs involved in the regulation of skeletal muscle mass in humans are largely unknown. MicroRNAs are short, noncoding RNAs that fine‐tune target expression through mRNA degradation or by inhibiting protein translation. Intronic to the slow, type I, muscle fiber type genes MYH7 and MYH7b, microRNA‐208b and microRNA‐499‐5p are thought to fine‐tune the expression of genes important for muscle growth, such as myostatin. Spinal cord injured humans are characterized by both skeletal muscle atrophy and transformation toward fast‐twitch, type II fibers. We determined the expression of microRNA‐208b, microRNA‐499‐5p, and myostatin in human skeletal muscle after complete cervical spinal cord injury. We also determined whether these microRNAs altered myostatin expression in rodent skeletal muscle. A progressive decline in skeletal muscle microRNA‐208b and microRNA‐499‐5p expression occurred in humans during the first year after spinal cord injury and with long‐standing spinal cord injury. Expression of myostatin was inversely correlated with microRNA‐208b and microRNA‐499‐5p in human skeletal muscle after spinal cord injury. Overexpression of microRNA‐208b in intact mouse skeletal muscle decreased myostatin expression, whereas microRNA‐499‐5p was without effect. In conclusion, we provide evidence for an inverse relationship between expression of microRNA‐208b and its previously validated target myostatin in humans with severe skeletal muscle atrophy. Moreover, we provide direct evidence that microRNA‐208b overexpression decreases myostatin gene expression in intact rodent muscle. Our results implicate that microRNA‐208b modulates myostatin expression and this may play a role in the regulation of skeletal muscle mass following spinal cord injury. © 2015 The Authors
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